Caribbean - Central America Weather

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1014 PM AST SAT AUG 14 2010

.UPDATE...THE AFTERNOON SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE
NORTHERN HALF OF PUERTO RICO...DISSIPATED RAPIDLY AFTER SUNSET. THE
NWS DOPPLER RADAR DETECTED ONLY ISOLATED TO SCATTERED SHOWER ACROSS
THE SURROUNDING COASTAL WATERS THIS EVENING...WITH AN ISOLATED
THUNDERSTORM ACROSS SOUTHWESTERN PUERTO RICO. A TROPICAL WAVE
LOCATED AT AROUND 48 WEST THIS EVENING...WILL CONTINUE TO MOVE
WEST...REACHING OUR FA ON TUESDAY MORNING.


LATEST WATER VAPOR IMAGERY DEPICTED AN INVERTED UPPER LEVEL TROUGH
JUST ACROSS THE NORTHEAST CARIBBEAN THIS EVENING. A PERSISTENT TUTT
LOW...WELL NORTH OF THE AREA WILL CONTINUE TO LIFT NORTHWARD DURING
THE NEXT FEW DAYS...DEVELOPING INTO A CLOSED LOW JUST ACROSS THE
NORTHWESTERN ATLANTIC LATE SUNDAY AND MONDAY. ANOTHER TUTT LOW...
ACROSS THE CENTRAL ATLANTIC...EAST NORTHEAST OF THE FA...WILL
AMPLIFY WESTWARD ACROSS THE NORTHEAST CARIBBEAN BY THE MIDDLE OF THE
WEEK. THESE FEATURES WILL MAINTAIN AND UNSTABLE UPPER LEVEL
ENVIRONMENT DURING THE NEXT SEVERAL DAYS. THE AVAILABLE LOW LEVEL
MOISTURE WILL COMBINE WITH THE UNSTABLE UPPER LEVEL ENVIRONMENT...
DIURNAL HEATING AND LOCAL EFFECTS TO INDUCE THE DEVELOPMENT OF
SCATTERED TO NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS MAINLY
ACROSS THE NORTHERN HALF OF PUERTO RICO...ESPECIALLY DURING THE
AFTERNOONS.

LOOKING WELL AHEAD...THE GFS MODEL GUIDANCE SUGGESTS THAT THE
TROPICAL ATLANTIC WILL BECOME ACTIVE VERY SOON AS SEVERAL LOW
PRESSURE SYSTEMS DEVELOP INTO TROPICAL CYCLONES. STAY TUNED

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL ACROSS TAF SITES THROUGH
15/12Z. LOW LVL CLDS BTW 020-070 KFT AND MOSTLY LIGHT PASSING
SHRA ARE PSBL EN ROUTE BTW PR...USVI...AND NRN LEEWARD ISLANDS BUT
OVERALL NO SIG FLYING HAZARDS EXPECTED AT THIS TIME FOR THE LOCAL
FLYING AREA.

[cycloneye]

Good morning.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
420 AM AST SUN AUG 15 2010

.SYNOPSIS...AN INVERTED UPPER LEVEL TROUGH EXTENDING ACROSS THE
MONA PASSAGE THIS MORNING...WILL ENHANCE SHOWER AND THUNDERSTORM
DEVELOPMENT ACROSS THE LOCAL ISLANDS TODAY. A WEAK TROPICAL WAVE
WILL APPROACH THE LOCAL AREA MONDAY NIGHT.

&&

.DISCUSSION...MIMIC-TPW PRODUCT AND PROGNOSTIC SOUNDINGS INDICATE
A GRADUAL INCREASE IN PW VALUES ACROSS THE LOCAL ISLANDS TODAY. AS
A RESULT...THE AVAILABLE MOISTURE AND FAVORABLE ATMOSPHERIC
CONDITIONS WILL COMBINE ONCE AGAIN WITH LOCAL AND DIURNAL EFFECTS
TO INDUCE CLOUDINESS...SHOWERS AND THUNDERSTORMS ACROSS THE INTERIOR
AND WESTERN SECTIONS OF PUERTO RICO EARLY THIS AFTERNOON. THESE
SHOWERS AND STORMS WILL BE CAPABLE OF PRODUCING LOCALLY HEAVY
RAIN...THEREFORE URBAN AND SMALL STREAM FLOODING WILL ALSO BE
LIKELY IN ISOLATED AREAS. DUE TO ALREADY SATURATED SOILS...ANY
ADDITIONAL RAINFALL WILL LIKELY RESULT IN RAPID RISES IN SMALL
STREAMS AND CREEKS AS WELL AS INCREASE THE POTENTIAL FOR MUDSLIDES
IN AREAS OF STEEP TERRAIN.

A WEAK TROPICAL WAVE IS EXPECTED TO APPROACH THE FORECAST AREA
LATE MONDAY NIGHT THROUGH TUESDAY...BRINGING ADDITIONAL LOW LEVEL
MOISTURE TO THE REGION...HOWEVER WIDESPREAD PRECIPITATION IS NOT
EXPECTED AT THIS TIME.

FOR LATE TUESDAY THROUGH FRIDAY...THE GFS AND NAM ARE BOTH INDICATING
PW VALUES WILL GRADUALLY DECREASE OVER THE NEXT SEVERAL DAYS BEHIND
THE AFOREMENTIONED TROPICAL WAVE. HOWEVER...PATCHES OF MOISTURE WILL
MOVE ACROSS THE LOCAL AREA FROM TIME TO TIME AND WILL COMBINE WITH
LOCAL AND DIURNAL EFFECTS TO RESULT IN A FEW EARLY MORNING PASSING
SHOWERS ACROSS SECTIONS OF EASTERN PUERTO RICO EACH MORNING...AND
THE DEVELOPMENT OF AFTERNOON SHOWERS AND THUNDERSTORMS ACROSS
WESTERN PUERTO RICO EACH AFTERNOON.

&&

.AVIATION...EXPECT PREVAILING VFR CONDITIONS ACROSS MOST OF THE
LOCAL ISLANDS AND AT ALL LOCAL TAF SITES THROUGH 15/16Z...BUT WITH
BRIEF MVFR CONDITIONS POSSIBLE IN SCATTERED SHOWERS OR AN ISOLATED
THUNDERSTORM OR TWO...MAINLY NEAR TIST AND TISX. AFTER 15/16Z...MVFR
CONDITIONS (LOCALLY IFR) AND MOUNTAIN OBSCURATIONS ARE EXPECTED TO
DEVELOP OVER THE INTERIOR...WEST AND NORTHWEST SECTIONS OF PUERTO
RICO...AND WILL LIKELY EXPAND TO NEAR OR OVER TJMZ...TJBQ AND
PROBABLY TJSJ BY 15/17Z OR 15/18Z...AND THEN CONTINUE THROUGH ABOUT
15/23Z.

&&

.MARINE...MARINERS SHOULD EXPECT WINDS OF 15 KNOTS OR LESS AND
SEAS OF 4 FEET OR LESS THROUGH MONDAY...WITH WINDS AND SEAS
INCREASING MONDAY NIGHT AND TUESDAY IN ASSOCIATION WITH THE
AFOREMENTIONED PASSING TROPICAL WAVE AND A LOW LEVEL WIND SURGE.
NO PRECAUTIONARY STATEMENTS IN EFFECT AT THIS TIME.

&&

[cycloneye]

Here is Sunday mornings discussion by Crownweather Services:

http://www.crownweather.com/?page_id=325

Eastern Atlantic Development This Week Through Next Week With Up To Two To Three Named Storms Possible:
Looking at the long range prospects. If the model guidance is to be believed, we are looking at a very busy 10 to 15 days across the Atlantic Basin with up to 3 additional tropical cyclones forecast. The latest GFS model is forecasting the following: A major hurricane to track out into the open Atlantic in about 8 to 10 days. A second major hurricane to impact the northern Leeward Islands around August 27th and then impact the Bahamas and threaten Florida around August 30th. The GFS model is also forecasting a third tropical cyclone to form around August 25th and impact the Windward Islands and Barbados around August 30th.

As for the other model guidance, the latest European model is forecasting tropical cyclone formation in the eastern Atlantic around August 19th with a second tropical cyclone forming in the far eastern Atlantic around August 24th. Looking at the setup based on the European model, I would suspect that the first tropical cyclone would track out into the open Atlantic, however, the second tropical cyclone forecast would need to be really monitored closely.

So, here are my thoughts: I strongly believe that in just 7 to 10 days from now, we will be tracking and monitoring multiple tropical cyclones in the Atlantic Basin. Things are anticipated to get very busy by late this week right through at least the end of the month. Personally, I wouldn’t concentrate on exact storm forecast details, but instead look at the overall pattern forecast to setup and the idea of at least two tropical cyclones forming in the eastern Atlantic seems quite possible. I also wanted to note that the European model ensemble guidance continues to be further south and west with the first tropical cyclone and it’s 10 day forecast is showing a strong ridge of high pressure across much of the Atlantic and this could mean we could see the first system track further west than what is currently being forecast by the model guidance.

[msbee]

good morning Luis
This is the part of that discussion that makes me nervous:

If the model guidance is to be believed, we are looking at a very busy 10 to 15 days across the Atlantic Basin with up to 3 additional tropical cyclones forecast. The latest GFS model is forecasting the following: A major hurricane to track out into the open Atlantic in about 8 to 10 days. A second major hurricane to impact the northern Leeward Islands around August 27th and then impact the Bahamas and threaten Florida around August 30th. The GFS model is also forecasting a third tropical cyclone to form around August 25th and impact the Windward Islands and Barbados around August 30th.

How reliable is the GFS generally?

[cycloneye]

good morning Luis
This is the part of that discussion that makes me nervous:

If the model guidance is to be believed, we are looking at a very busy 10 to 15 days across the Atlantic Basin with up to 3 additional tropical cyclones forecast. The latest GFS model is forecasting the following: A major hurricane to track out into the open Atlantic in about 8 to 10 days. A second major hurricane to impact the northern Leeward Islands around August 27th and then impact the Bahamas and threaten Florida around August 30th. The GFS model is also forecasting a third tropical cyclone to form around August 25th and impact the Windward Islands and Barbados around August 30th.

How reliable is the GFS generally?

Good morning Barbara. The long range runs like what GFS does after 192 hours are not the best thing to follow because it changes a lot with each run. The best timeframe to look at the GFS and the other models is until 144 hours.

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
238 PM AST SUN AUG 15 2010

.SYNOPSIS...WEAK UPPER LEVEL TROUGH WILL LINGER ACROSS THE MONA
PASSAGE AT LEAST THROUGH MONDAY. MID TO UPPER LEVEL RIDGE WILL
BUILD ACROSS THE WESTERN ATLANTIC THROUGH TUESDAY. WEAK TROPICAL
WAVE WILL APPROACH THE LOCAL AREA FROM THE EAST TUESDAY. UPPER
LEVEL TROUGH WILL MOVE ACROSS THE NORTHEAST CARIBBEAN THURSDAY.

&&

.DISCUSSION...THIS AFTERNOON...STRONG THUNDERSTORMS DEVELOPED
NEAR EL YUNQUE RAIN FOREST...AND THIS ACTIVITY WAS MOVING SLOWLY
NORTHWEST. OTHER AREAS OF SHOWERS AND THUNDERSTORMS WERE OCCURRING
LATE THIS AFTERNOON ACROSS THE CORDILLERA CENTRAL FROM
CIDRA...WESTWARD THROUGH LAS MARIAS. THIS ACTIVITY DEVELOPED DUE
TO THE INTERACTION WITH A WEAK UPPER LEVEL TROUGH TO OUR WEST...AND
STRONG DAYTIME HEATING AT THE SURFACE. THIS ACTIVITY IS EXPECTED
TO DIMINISH NEAR SUNSET TONIGHT. THIS WEATHER PATTERN IS NOT
EXPECTED TO CHANGE TOO MUCH AT LEAST THROUGH TUESDAY...WITH MOST
OF THE ACTIVITY OCCURRING EVERY AFTERNOON EACH DAY. FOR
TUESDAY...A WEAK TROPICAL WAVE IS EXPECTED TO APPROACH THE LOCAL
AREA FROM THE EAST...INCREASING THE SHOWER ACTIVITY ACROSS THE
LOCAL AREA. FOR THURSDAY...AN UPPER LEVEL TROUGH IS EXPECTED TO
APPROACH THE LOCAL AREA FROM THE EAST...WITH THE GFS SHOWING THE
BETTER MOISTURE FOR THIS DAY. PROG SOUNDINGS FROM SJU-GFS COMPUTER
MODEL SUGGEST A DECREASE IN PW VALUES BY MID WEEK...ESPECIALLY FOR
WEDNESDAY NIGHT THROUGH FRIDAY. THIS COULD BE IN RESPONSE TO THE
SAHARAN AIR LAYER MOVING ACROSS THE LOCAL AREA. LATEST NAAPS
AEROSOL FORECAST INDICATED AN AREA OF SAL ARRIVING TO OUR LOCAL
AREA THESE DAYS. THEREFORE...SOME HAZY SKIES AND "DRIER"
CONDITIONS COULD BE POSSIBLE. HOWEVER...PW VALUES ARE EXPECTED TO
REMAIN HIGH...AND THE AFOREMENTIONED UPPER LEVEL TROUGH WILL BE LOCATED
TO OUR WEST AT THE END OF THE WEEK...ENHANCING THE DEVELOPMENT OF
SHOWERS AND THUNDERSTORMS ACROSS THE WESTERN INTERIOR SECTION OF
PUERTO RICO. IN THE LONG TERM...COMPUTER MODELS STILL SUGGEST THAT
CYCLONGENESIS WILL OCCUR AS EARLY AS NEXT WEDNESDAY ACROSS THE
TROPICAL ATLANTIC. ALTHOUGH IS TOO EARLY TO KNOW EXACTLY IS THIS
WILL VERIFY...WE ARE APPROACHING THE MOST ACTIVE PERIOD OF THE
HURRICANE SEASON. STAY TUNED FOR FURTHER INFORMATION.

&&

.AVIATION...MVFR CONDITIONS WITH MOUNTAIN OBSCURATION WILL PREVAIL
ACROSS TJMZ...AND TJBQ AT LEAST THROUGH 15/22Z. ALSO...MVFR
CONDITIONS ARE POSSIBLE ACROSS TIST AT LEAST THROUGH 14/21Z. VFR
CONDITIONS WILL PREVAIL ACROSS THE REST OF THE TAF SITES TONIGHT.
LIGHT PASSING SHOWERS ARE POSSIBLE ACROSS TIST AND TISX.

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
942 PM AST SUN AUG 15 2010

.UPDATE...THE AFTERNOON SHOWER AND THUNDERSTORM ACTIVITY ACROSS
SOUTHEASTERN AND THE NORTHERN HALF OF PUERTO RICO...DISSIPATED
RAPIDLY AFTER SUNSET. THE NWS DOPPLER RADAR DETECTED ONLY ISOLATED
TO SCATTERED SHOWER ACROSS THE SURROUNDING COASTAL WATERS THIS
EVENING...WITH AN ISOLATED THUNDERSTORM ACROSS WESTERN PUERTO
RICO LASTING UNTIL THE EARLY EVENING HOURS. THE AFTERNOON SHOWER
AND THUNDERSTORM ACTIVITY DEVELOPED DUE TO THE COMBINATION OF THE
STRONG DAYTIME HEATING...LOCAL ISLAND EFFECT ENHANCED BY A WEAK
UPPER LEVEL TROUGH JUST WEST OF THE FA. BY TUESDAY A WEAK
TROPICAL WAVE WILL APPROACH TO THE REGION INCREASING EVEN MORE THE
CHANCES OF SHOWERS AND THUNDERSTORMS ACROSS THE LOCAL ISLANDS. AN
UPPER LEVEL TROUGH...TUTT LOW...EAST NORTHEAST OF THE REGION THIS
EVENING...WILL MOVE WESTWARD DURING THE NEXT FEW DAYS AND IS
EXPECTED TO REACH THE FA LATE WEDNESDAY AND THURSDAY. SEVERAL LOW
LEVEL REFLECTIONS OF THE AFOREMENTIONED TUTT LOW WILL MOVE ACROSS
THE REGION FROM TIME TO TIME LATE IN THE WORK WEEK...MAINTAINING
ABUNDANT LOW LEVEL MOISTURE ACROSS THE LOCAL ISLANDS TO COMBINE
WITH DAYTIME HEATING AND GOOD UPPER LEVEL DYNAMIC TO IGNITE
SHOWERS AND THUNDERSTORMS EACH AFTERNOON. LOOKING WELL
AHEAD...COMPUTER MODELS GUIDANCE SUGGEST THAT THE TROPICAL
ATLANTIC WILL BECOME A LITTLE MORE ACTIVE DURING THE NEXT FEW
WEEKS AS SEVERAL LOW PRESSURE SYSTEMS DEVELOP INTO TROPICAL
CYCLONES. STAY TUNED

&&

.AVIATION...EXPECT PREVAILING VFR CONDS ACROSS TAF SITES OF PR AND
USVI AT LEAST TIL 16/04Z.THEREAFTER AND UNTIL 16/13Z EXPECT BRIEF
MVFR CONDS DUE TO PASSING SHOWERS VCNTY OF TJSJ...TJNR... TISX AND
TIST. MTN TOP OBSCR ALSO PSBL ACROSS EAST SECTIONS OF THE CORDILLERA
CENTRAL OF PR THROUGH 16/12Z...DUE TO PASSING LOW LEVEL CLOUDS AND
SHRA. THE NORTHERN LEEWARDS TO INCLUDE TNCM AND TKPK ALSO WILL
EXPERIENCE TEMPO MVFR AT LEAST THROUGH 16/10Z DUE TO PASSING SHOWERS
IN ADVANCE OF A TROPICAL WAVE MOVING ACROSS THE EASTERN CARIBBEAN.

[cycloneye]

Good morning. A Tropical Wave will move thru the Eazstern Caribbean today.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
527 AM AST MON AUG 16 2010

.SYNOPSIS...A TUTT (LOW) OVER HISPANIOLA WILL CONTINUE MOVING WEST
TODAY...LEAVING RATHER WEAK UPPER FLOW ACROSS THE LOCAL AREA
THROUGH EARLY TUESDAY. A TROPICAL WAVE WILL APPROACH THE LOCAL
AREA TODAY THROUGH EARLY TONIGHT AND THEN MOVE ACROSS THE LOCAL
ISLANDS LATE TONIGHT THROUGH TUESDAY. A MID TO UPPER LEVEL RIDGE
WILL EXTEND INTO THE LOCAL AREA LATER TUESDAY THROUGH WEDNESDAY OR
WEDNESDAY NIGHT. A NEW TUTT WILL APPROACH THE NORTHEAST CARIBBEAN
WEDNESDAY NIGHT OR EARLY THURSDAY AND WILL ACT TO RE-ALIGN THE
TUTT AXIS NORTH OF THE LOCAL AREA FOR LATER THURSDAY THROUGH
FRIDAY.

&&

.DISCUSSION...ENOUGH MOISTURE AND INSTABILITY WILL REMAIN ACROSS
THE LOCAL AREA TODAY TO COMBINE WITH LOCAL EFFECTS AND MAINLY
FAVORABLE UPPER LEVEL CONDITIONS...TO PRODUCE SOME CLOUDINESS...
SHOWERS AND A FEW THUNDERSTORMS OVER PARTS OF THE LOCAL ISLANDS.
AFOREMENTIONED TROPICAL WAVE WILL APPROACH THE LOCAL AREA TODAY
THROUGH EARLY TONIGHT AND THEN MOVE ACROSS THE LOCAL ISLANDS LATE
TONIGHT THROUGH TUESDAY...BRINGING ADDITIONAL MOISTURE TO THE
LOCAL AREA...RESULTING IN MORE CLOUDINESS...SHOWERS AND
THUNDERSTORMS. SOME OF THESE SHOWERS AND STORMS WILL CONTAIN
BRIEF STRONG AND GUSTY WINDS...FREQUENT LIGHTNING...AND PERIODS
OF HEAVY RAIN THAT WILL RESULT IN SOME MINOR LOW LYING FLOODING.
MOISTURE APPEARS TO LINGER THROUGH TUESDAY NIGHT/EARLY
WEDNESDAY...BEFORE AN "OVERALL DRIER AND MORE STABLE" AIR MASS
WITH SAL ENCOMPASSES THE FA FOR LATER WEDNESDAY THROUGH THURSDAY
AND POSSIBLY FRIDAY. EXPECT LESS CONVECTIVE ACTIVITY FOR THIS
WEDNESDAY THROUGH FRIDAY TIME FRAME...BUT CERTAINLY WILL NOT BE
COMPLETELY DRY...AS RE-ALIGNING TUTT TO OUR NORTH WILL AID IN
LOCAL SHOWER AND THUNDERSTORM DEVELOPMENT EACH AFTERNOON.

OPTED TO LOWER GFS MEX MAX TEMPERATURES FOR SAN JUAN 2 DEGREES
TODAY...TUESDAY AND WEDNESDAY AND 1 DEGREE FOR THURSDAY...AS PAST
DAYS TREND HAS BEEN TO REMAIN BELOW GUIDANCE AND UPCOMING ACTIVE
WEATHER AND GENERALLY EAST NORTHEAST TO EAST WIND FLOW...WILL NOT
BE CONDUCIVE TO LOWER 90S ALONG THE IMMEDIATE NORTH COASTAL
SECTIONS OF PUERTO RICO.

&&

.AVIATION...EXPECT PREVAILING VFR CONDS AT ALL TAF SITES THROUGH
16/15Z...WITH BRIEF MVFR CONDS POSSIBLE IN PASSING SHOWERS OVER
TIST/TISX...TNCM/TKPK AND TJSJ. MTN TOP OBSCR AND TEMPO MVFR CONDS
EXPECTED TO DEVELOP IN AND AROUND TJMZ BY 16/16Z OR 16/17Z IN
SHRA/TSRA...AND THEN CONTINUE THROUGH ABOUT 16/23Z.

&&

.MARINE...MARINERS SHOULD EXPECT WINDS OF 16 KNOTS OR LESS AND
SEAS OF 4 FEET OR LESS THROUGH TODAY...WITH WINDS AND SEAS
INCREASING TONIGHT AND TUESDAY AND THEN CONTINUING TUESDAY NIGHT
AND WEDNESDAY...IN ASSOCIATION WITH THE PASSING TROPICAL WAVE AND
A LOW LEVEL WIND SURGE. NO PRECAUTIONARY STATEMENTS IN EFFECT AT
THIS TIME...BUT THEY WILL LIKELY BE NEEDED TONIGHT FOR MOST OF THE
LOCAL WATERS.

&&

[msbee]

good mornign
where is everyone Luis?
I only see you posting.
I wonder what happend to Gusty and others?

Here is this morning's tropical discussion from Crownweather:

Issued: Monday, August 16, 2010 615 am EDT/515 am CDT

For the Tropical Weather Discussion with Maps, Images and Graphics, Go To: http://www.crownweather.com/?page_id=325.


Discussion
Ex-Tropical Depression #5:
It appears that Ex-Tropical Depression #5 is now moving into the waters of the northern Gulf of Mexico just south of the western part of the Florida Panhandle. Radar imagery and satellite loops indicate that this system is organizing and developing and I think it is likely that we will see this re-classified as a tropical depression sometime today, most likely when reconnaissance aircraft investigates it this afternoon. Environmental conditions are fairly favorable for development and intensification. The only things that I see that may prevent development and intensification is the proximity to land and also some dry air that can be observed on water vapor satellite imagery over Texas that may be drawn into the circulation.

I think you will see gradual development and intensification today and as I have already mentioned I think it is likely we will see this re-classified as Tropical Depression 5 this afternoon. As we head into tonight and Tuesday morning, further organization and intensification is expected and I expect this to reach tropical storm strength (its name will be Danielle) during Tuesday morning before making landfall Tuesday afternoon as a 50 to 70 mph tropical storm somewhere between Grand Isle and Houma, Louisiana.

Ex-Tropical Depression 5 will track south and southwest today and then turn to the west tonight and then northwest on Tuesday. As I have already mentioned, a landfall somewhere between Grand Isle and Houma, Louisiana seems likely during Tuesday afternoon as a 50 to 70 mph tropical storm.

The main threat from this system will continue to be heavy rainfall and inland flooding. Additional rainfall totals across southeast Louisiana will average between 4 and 8 inches over the next 2 to 3 days. This is on top of the heavy rain that has already accumulated. Needless to say, significant flooding seems likely and those of you prone to inland flooding should monitor the latest flood watches, warnings and statements from your local National Weather Service office and take appropriate action if necessary.

I will be monitoring Ex-Tropical Depression 5 very closely and will keep you all updated.

Eastern Atlantic Development Later This Week Seems Likely:
Even though it is way out in the far eastern Atlantic, I am closely monitoring a tropical wave that will emerge off of the coast of Africa within the next 24 hours. Satellite imagery indicates that this wave is traveling fairly far north in latitude, near 15 or 16 North Latitude. Environmental conditions are favorable for development and I suspect that this will develop into a tropical depression and then a tropical storm later this week in the eastern Atlantic. This system has unanimous model support in that it will significantly develop over the next 7 to 10 days and I agree with the model guidance forecasts.

The various guidance like the GFS and European models are forecasting that this system will eventually curve out into the open Atlantic in about 8 to 10 days. One thing that kind of looks strange to me is that the GFS model forecast's upper level forecast of a high pressure ridge to the north of this system in about a week from now would lead me to believe that this system would track further west and it doesn't make sense that it would be turning into a high pressure ridge as that is not meteorologically sound. It should be noted that the Canadian model forecasts an eventual track that takes it towards the Bahamas in 10 days. So, the forecast by the model guidance of a curve out into the Atlantic may not be entirely correct, however, the odds of this system curving out into the Atlantic are kind of high because it is coming off of the coast of Africa at such a high latitude. With that said, curvature out into the open Atlantic is not a guarantee and this first system will be watched closely.

A second tropical wave now located over eastern Nigeria may be much more trouble and this one really needs to be watched closely. This second tropical wave will emerge into the eastern Atlantic late this week or this weekend. This system will be traveling at a much lower latitude and has the chance to be caught underneath a ridge of high pressure and could potentially be a threat to the US coastline way down the road. One thing to note in the model guidance forecast for this second tropical wave is the fact that it keeps it fairly weak which would tend to cause it to travel "underneath the radar" and potentially be a real problem once it gets west of 55 or 60 West Longitude.

The model guidance as a whole continues to beat the drum that a period of little or no break between tropical storms and hurricanes developing out in the Atlantic is about to begin and at times we could see a train of storms tracking westward. In fact, I noticed that the latest European model is forecasting 13 named storms after September 1st and the long range CFS model is forecasting an extremely busy September with the potential for a near record number storms for the month of September. So, I suspect that we may have at least two to three more named storms for the month of August (Danielle in the northern Gulf of Mexico and Earl and possibly Fiona in the far eastern Atlantic) and then if the European model is to be believed (and I do) then at least an additional 13 named storms after September 1st.

The next tropical weather discussion will be issued by 7 am EDT/6 am CDT Tuesday morning.

[cycloneye]

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE SAN JUAN PR
322 PM AST MON AUG 16 2010

.SYNOPSIS...TROPICAL WAVE NOW LOCATED ACROSS THE LESSER ANTILLES
WILL APPROACH THE LOCAL AREA THIS EVENING THROUGH TOMORROW...
RESULTING IN ACTIVE WEATHER PATTERN...AS WELL AS AN INCREASE IN
WINDS AND SEAS ACROSS THE REGIONAL WATERS.

&&

.DISCUSSION...LOCALLY HEAVY DOWNPOURS WITH REDUCED VISIBILITIES WERE
OBSERVED OVER PORTIONS OF ST. CROIX EARLY THIS AFTERNOON. RAINFALL
AMOUNTS OF AROUND HALF AN INCH WERE MEASURED IN THE CHRISTIANSTED
AIRPORT BETWEEN 17-18Z. ACROSS PUERTO RICO...THE SHOWER ACTIVITY
DEVELOPED DUE TO THE INTERACTION OF THE SEA BREEZE CONVERGENCE...
AVAILABLE MOISTURE AND STRONG DAYTIME HEATING AT THE SURFACE TO
PRODUCED SHOWERS AND THUNDERSTORMS OVER THE INTERIOR AND WESTERN
PORTIONS OF PUERTO RICO. THIS ACTIVITY IS EXPECTED TO DIMINISH
AFTER SUNSET.

LATEST SATELLITE DERIVED PRODUCTS...WINDSAT SCATTEROMETER
AND THE BLENDED TPW IMAGERY INDICATED A SURGE OF WIND AND DEEP
MOISTURE ASSOCIATED WITH THE TROPICAL WAVE ACROSS THE LESSER
ANTILLES. THIS FEATURE WILL CONTINUE TO MOVE WESTWARD ACROSS THE
CARIBBEAN WATERS...AND BRING AN INCREASE MOISTURE WITH HIGHER TPW
VALUES ACROSS THE LOCAL AREA AND ALSO INCREASE THE CHANCES FOR
ACTIVE AND SQUALLY WEATHER CONDITIONS ACROSS THE ISLANDS AND
SURROUNDING WATERS DURING THE NEXT DAY OR TWO. CLOUDS AND SHOWERS
WILL INITIALLY AFFECT THE U.S. VIRGIN ISLANDS THIS EVENING...
WHILE INCREASING IN SHOWER ACTIVITY CAN BE EXPECTED TO SPREAD
WESTWARD ACROSS THE PUERTO RICO THROUGH THE OVERNIGHT AND EARLY
MORNING HOURS.

NUMERICAL WEATHER MODELS SUGGEST AN OVERALL DRYING TREND FROM
WEDNESDAY THROUGH FRIDAY...WHILE DRIER AND MORE STABLE AIR MASS FROM
THE EAST APPROACHES TO THE LOCAL REGION. HOWEVER...EXPECT THE USUAL
AFTERNOON CONVECTION OVER THE WESTERN PORTIONS OF PUERTO RICO. THIS
SHOWER AND THUNDERSTORM ACTIVITY WILL BE LIMITED...BUT MAY OCCUR
PERIODS OF LOCALLY HEAVY RAIN...FREQUENT LIGHTNING AND GUSTY WINDS
NEAR THUNDERSTORMS.


&&

.AVIATION...MVFR CONDITIONS WITH MOUNTAIN OBSCURATION WILL PREVAIL
ACROSS TJMZ AT LEAST THROUGH 16/22Z. ALSO...MVFR CONDITIONS WILL
OCCUR ACROSS TKPK...AND TNCM FROM 16/22 THROUGH AT LEAST 17/12Z...AS
A TROPICAL WAVE MOVES OVER THE AREA. SOME PASSING SHOWERS ARE
POSSIBLE ACROSS TJSJ...TIST...AND TISX TONIGHT...BUT WILL BECOME
MORE FREQUENTS AS NIGHT PROGRESS. THEREFORE...BRIEF PERIODS OF MVFR
CONDITIONS WILL BE POSSIBLE STARTING AROUND 17/04Z THROUGH AT LEAST
17/16Z.


&&

.MARINE...MARINERS SHOULD EXPECT WINDS OF 20 KNOTS OR LESS AND SEAS
OF 5 FEET OR LESS THROUGH TODAY...WITH WINDS AND SEAS INCREASING
DURING THE NEXT DAYS...IN ASSOCIATION WITH THE PASSING TROPICAL
WAVE AND A LOW LEVEL WIND SURGE. TRADES WILL INCREASE FROM 15-25 KTS...
ESPECIALLY OVER CARIBBEAN WATERS FROM TUESDAY THROUGH WEDNESDAY. NO
PRECAUTIONARY STATEMENTS IN EFFECT AT THIS TIME...BUT THEY WILL
LIKELY BE NEEDED TOMORROW FOR MOST OF THE LOCAL WATERS.

&&

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
946 PM AST MON AUG 16 2010

.UPDATE...TROPICAL WAVE LOCATED NEAR 64 WEST LATE THIS EVENING
WILL CONTINUE TO MOVE WEST AND WILL ENTER OUR REGIONAL WATERS
OVERNIGHT. LATEST SATELITE IMAGES SHOWS PLENTY OF MOISTURE
APPROACHING THE LOCAL AREA. LATEST TJSJ 17/00Z SOUNDING REVEALED
PRECIPITABLE WATER VALUE WENT UP...WITH 2.12 INCHES...COMPARED TO
16/12Z SOUNDING WHICH WAS 1.81 INCHES. LOOKS LIKE THE BEST
MOISTURE ASSOCIATED WITH THE WAVE WILL PASS SOUTH OF THE AREA.
HOWEVER..THE NORTHERN PART OF THE WAVE IS ACTIVE.
THEREFORE...EXPECT AN INCREASE IN SHOWER ACTIVITY STARTING
OVERNIGHT...AND LASTING THROUGH MOST OF THE DAY TOMORROW...AS THE
WAVE COMBINE WITH DAYTIME HEATING TOMORROW AFTERNOON TO PRODUCE
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS MOST OF THE
AREA. NO CHANGES WERE MADE TO LONG TERM GRIDS...WHICH ARE IN TRACK
WITH CURRENT FORECAST MODEL DATA.

&&

.AVIATION...TROPICAL WAVE APCHG TIST/TISX. FEW SHWRS AT TNCM AND AND
TKPK. SHWRS OR TRWS MAY BE EXPECTED AT TIST AND TISX THROUGH 17/12Z.
ALTHOUGH A FEW SHWRS MAY OCCUR AT TJBQ...SHWRS AND TRWS SHOULD NOT
RECOMMENCE UNTIL AFT 17/15Z AT TJMZ. SHWRS WILL INCREASE ARND TJSJ
THROUGH 17/12Z BUT CONDS WILL REMAIN PREDOMINANTLY VFR. WATCH FOR
MTN OBSCURATIONS INCREASING THROUGH 17/15Z AND THEN BECOMING
WIDESPREAD OVR WRN PR AFT 17/16Z.

[cycloneye]

Good morning.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
526 AM AST TUE AUG 17 2010

.SYNOPSIS...A TROPICAL WAVE EXTENDING FROM THE ATLANTIC COASTAL
WATERS SOUTHWEST ACROSS PUERTO RICO AND THEN CONTINUING ACROSS THE
CARIBBEAN EARLY THIS MORNING...WILL CONTINUE MOVING WEST NORTHWEST
ACROSS THE REMAINDER OF THE LOCAL AREA TODAY AND THEN AWAY FROM
THE REGION TONIGHT. A MID TO UPPER LEVEL RIDGE WILL EXTEND INTO
THE LOCAL AREA LATER TODAY THROUGH WEDNESDAY OR WEDNESDAY NIGHT.
A TUTT (LOW) WILL APPROACH THE NORTHEAST CARIBBEAN WEDNESDAY
NIGHT OR EARLY THURSDAY AND WILL ACT TO RE-ALIGN THE TUTT AXIS
NORTH OF PUERTO RICO AND THE U.S. VIRGIN ISLANDS FOR LATER
THURSDAY THROUGH FRIDAY AND PROBABLY SATURDAY.

&&

.DISCUSSION...THE TROPICAL WAVE AND ITS ASSOCIATED MOISTURE AND
INSTABILITY WILL CONTINUE TO MOVE ACROSS THE LOCAL AREA TODAY AND
WILL COMBINE WITH LOCAL EFFECTS AND MAINLY FAVORABLE UPPER LEVEL
CONDITIONS...TO PRODUCE SOME CLOUDINESS...SHOWERS AND A FEW
THUNDERSTORMS OVER PARTS OF THE LOCAL ISLANDS. SOME OF THESE
SHOWERS AND STORMS WILL CONTAIN BRIEF STRONG AND GUSTY WINDS...
FREQUENT LIGHTNING...AND PERIODS OF HEAVY RAIN THAT WILL RESULT
IN SOME MINOR LOW LYING FLOODING. THIS WAVE WILL MOVE AWAY FROM
THE REGION TONIGHT...BUT MOISTURE WILL LINGER THROUGH TONIGHT AND
EARLY WEDNESDAY...BEFORE AN "OVERALL DRIER AND MORE STABLE" AIR
MASS AND SAL ENCOMPASS THE FA FOR LATER WEDNESDAY AND THURSDAY
AND PROBABLY CONTINUING THROUGH FRIDAY AND SATURDAY. HOWEVER...
ALTHOUGH STILL EXPECT LESS CONVECTIVE ACTIVITY FOR THIS TIME
FRAME...CERTAINLY WILL NOT BE COMPLETELY DRY...AS RE-ALIGNING TUTT
TO OUR NORTH WILL AID IN LOCAL SHOWER AND THUNDERSTORM DEVELOPMENT
EACH AFTERNOON.

&&

.AVIATION...A TROPICAL WAVE OVER THE LOCAL AREA MAY INDUCE BRIEF
MVFR CONDS IN PASSING SHOWERS AND THUNDERSTORMS ACROSS TIST/TISX
AND TJSJ/TJPS THROUGH 17/15Z...ELSEWHERE VFR CONDS EXPECTED. MTN
TOP OBSCR AND TEMPO MVFR CONDS EXPECTED TO DEVELOP OVER THE
INTERIOR...AND WEST SECTIONS OF PR...INCLUDING IN AND AROUND TJMZ
AND TJBQ BY 17/16Z OR 17/17Z IN SHRA/TSRA...AND THEN CONTINUE
THROUGH ABOUT 17/23Z.

&&

.MARINE...MARINERS SHOULD EXPECT WINDS OF 21 KNOTS OR LESS AND
SEAS OF 6 FEET OR LESS ACROSS THE REGIONAL WATERS THROUGH
THURSDAY...BUT GENERALLY HIGHEST TODAY THROUGH WEDNESDAY. SMALL
BOAT OPERATORS SHOULD EXERCISE CAUTION ACROSS MOST OF THE LOCAL
COASTAL WATERS TODAY.

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
249 PM AST TUE AUG 17 2010

.SYNOPSIS...A TROPICAL WAVE NOW LOCATED OVER THE EASTERN HISPANOLA
THIS AFTERNOON...WILL MOVE AWAY FROM THE REGION TONIGHT...BUT
MOISTURE WILL LINGER THROUGH OVERNIGHT HOURS. THEN...DRIER AND
MORE STABLE AIR MASS FROM THE EAST APPROACHES TO THE LOCAL REGION.


&&

.DISCUSSION...AN AREA OF SHOWERS AND THUNDERSTORMS...ASSOCIATED
WITH THE TROPICAL WAVE...WILL CONTINUE TO GENERATE SCATTERED
SHOWERS AND THUNDERSTORMS ACROSS THE SURROUNDING WATERS...PUERTO
RICO AND THE LOCAL ISLANDS DURING THE REST OF THE AFTERNOON HOURS.
IN FACT...LATER RADAR OBSERVATIONS... INDICATED SHOWERS AND
THUNDERSTORMS ACROSS PARTS OF THE EASTERN HALF OF PUERTO RICO AND
THE LOCAL ISLANDS. HOWEVER...THE MOST INTENSE THUNDERSTORMS ARE
LOCATED ACROSS THE OFFSHORE CARIBBEAN WATERS AND THE MONA PASSAGE.
THIS WAVE WILL MOVE AWAY FROM THE REGION TONIGHT...BUT MOISTURE
WILL LINGER THROUGH OVERNIGHT HOURS.

LATEST VISIBLE SATELLITE IMAGERY SHOWED A DRIER AIR MASS NOW
LOCATED ACROSS THE LESSER ANTILLES. LATEST TPW PRODUCTS AS WELL AS
SAL ANALYSIS INDICATED DECREASING PRECIPITABLE WATER OVER NEXT FEW
DAYS...SO EXPECT OVERALL DRYING TREND FROM TOMORROW THROUGH
FRIDAY. HOWEVER...SOME AFTERNOON CONVECTION IS POSSIBLE ACROSS THE
WEST AND WEST INTERIOR SECTIONS OF PUERTO RICO DURING THE NEXT
DAYS. MORE ACTIVE WEATHER IS EXPECTED FOR FRIDAY AS THE TUTT LOW
MOVES NORTH OF THE LOCAL ISLANDS.


&&

.AVIATION...TROPICAL WAVE OVER THE EASTERN HISPANIOLA WILL CONTINUE
TO MOVE WESTWARD AND AWAY FROM THE LOCAL REGION LATER TONIGHT.
LINGERING MOISTURE WILL GENERATE SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS OVER THE CARIBBEAN AND ATLANTIC WATERS FOR THE NEXT 12
HOURS. WINDS REPORTS WERE AT AROUND 20 KNOTS NEAR THE STRONGEST
THUNDERSTORMS. MVFR CONDITIONS ARE POSSIBLE OVER TJMZ...TJBQ AND
TJPS. AFTER 04Z...VFR CONDITIONS WILL PREVAIL ACROSS ALL TERMINALS.


&&

.MARINE...MARINERS SHOULD EXPECT WINDS OF 20 KNOTS OR LESS AND
SEAS OF 6 FEET OR LESS ACROSS THE REGIONAL WATERS THROUGH
THURSDAY...BUT GENERALLY HIGHEST TODAY THROUGH WEDNESDAY. SMALL
BOAT OPERATORS SHOULD EXERCISE CAUTION ACROSS MOST OF THE LOCAL
COASTAL WATERS TODAY.

[cycloneye]

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SAN JUAN PR
810 PM AST TUE AUG 17 2010

.UPDATE...CONVECTION THAT IS PEAKING IN THE TROPICAL WAVE THIS
EVENING...EXTENDS FROM CABO ROJO TO 80 MILES SOUTH SOUTHEAST OF
CAYEY PUERTO RICO. HEAVY RAINS MOVED INTO GUANICA AND CABO ROJO
AND HORMIGUEROS AFTER 7 PM AST...AND WILL NOW LIKELY EXTEND INTO
MAYAGUEZ FOR A FEW HOURS. A FEW SHOWERS ARE EAST OF A LINE THAT
EXTENDS SOUTHEAST OF PENUELAS...MAINLY ON THE SOUTH COAST FROM
JUANA DIAZ TO MAUNABO AND JUST OFSHORE FRO NORTHEAST PUERTO RICO
AND NORTH OF CULEBRA. HEAVIER SHOWERS ARE IN THE OFFSHORE ATLANTIC
WATERS NORTH OF AGUADILLA. THE SHOWERS NORTH OF PUERTO RICO ARE
MOVING NORTHWEST AND ARE NOT LIKELY TO AFFECT THE ISLAND. ALSO THE
NORTHWEST INTERIOR MAY SEE SOME CLOUDS BUT FEW SHOWERS ARE LIKELY
SO LATE. HAVE UPDATED GRIDS TO REFLECT PASSING WAVE.


&&

.DISCUSSION...IN THE LATER TERM THE APPROACH OF A TUTT LOW WILL
PRODUCE FAVORABLE CONDITION OVER THE AREA AND HAVE ADJUSTED POPS
THURSDAY THROUGH FRIDAY MORNING. THE NEXT TROPICAL WAVE MAY BE
CONNECTED TO AN APPROACHING TROPICAL SYSTEM AND IS ALSO EXPECTED
TO BRING INCREASED SHOWER ACTIVITY ON MONDAY AND TUESDAY.

IT IS STILL TOO EARLY TO SAY MUCH ABOUT THE SYSTEM EXPECTED IN BOTH
THE GFS AND ECMWF THAT PASSES NORTHEAST OF THE AREA...POSSIBLY ON
THURSDAY OF NEXT WEEK...BY VERY LITTLE OR A CONSIDERABLE
DISTANCE...DEPENDING ON MODEL RUN TIME AND TYPE...BUT MODELS HAVE
BEEN ADVERTISING DEVELOPMENT FOR OVER 48 HOURS WITH ROUGHLY
SIMILAR TRACKS AND TIMING.

[cycloneye]

Good morning. Hazy conditions for today but more west during next weekend.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
415 AM AST WED AUG 18 2010

.SYNOPSIS...A TROPICAL WAVE LOCATED ACROSS WESTERN HISPANIOLA THIS
MORNING...WILL MOVE AWAY FROM THE REGION TODAY. HOWEVER A LARGE
AREA OF MOISTURE BEHIND THE TROPICAL WAVE WILL CONTINUE TO PROMOTE
THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS ACROSS THE WESTERN
COASTAL WATERS. A RELATIVELY DRIER AIR MASS WILL ENCOMPASS THE
REGION FROM THE EAST STARTING TODAY. A TUTT WILL APPROACH TO THE
REGION FROM THE EAST LATE THURSDAY AND FRIDAY INDUCING AGAIN
AN INCREASE IN MOISTURE ACROSS THE REGION.

&&

.DISCUSSION...LATEST RADAR AND SATELLITE OBSERVATIONS EARLY THIS
MORNING DEPICTED SCATTERED SHOWERS AND THUNDERSTORMS MAINLY ACROSS
THE SURROUNDING COASTAL WATERS. FEW OF THESE SHOWERS AND
THUNDERSTORMS BRUSHED THE NORTHEASTERN SECTIONS OF PUERTO RICO AS
WELL AS VIEQUES...CULEBRA AND THE U.S. VIRGIN ISLANDS. THIS ACTIVITY
WAS ASSOCIATED WITH A TRAILING MOISTURE LEAVING BEHIND A TROPICAL
WAVE ACROSS HAITI THIS MORNING. THE WAVE WILL MOVE WELL AWAY FROM
THE FA TODAY.

LATEST SATELLITE IMAGERY AND MIMIC-TPW FROM CIMSS ALSO SHOWED A
DRIER AIR MASS NOW LOCATED ACROSS THE EASTERN CARIBBEAN AND THE
LESSER ANTILLES. LATEST TPW PRODUCTS AS WELL AS SAL ANALYSIS
INDICATED DECREASING PRECIPITABLE WATER OVER NEXT FEW DAYS...SO
EXPECT A RELATIVELY DRYING TREND FROM TODAY THROUGH FRIDAY. IN
FACT...THE GFS GUIDANCE SUGGESTS PWAT VALUES WELL BELOW 2.0 INCHES
FOR THE NEXT FEW DAYS. HOWEVER...SOME AFTERNOON CONVECTION WILL
CONTINUE ACROSS THE WEST AND WEST INTERIOR SECTIONS OF PUERTO RICO
DURING THE NEXT FEW DAYS. A TUTT LOW EAST OF THE FA THIS MORNING
WILL MOVE CLOSER OR ACROSS THE REGION LATE THURSDAY AND FRIDAY.
SEVERAL LOW LEVEL REFLECTIONS OF THE AFOREMENTIONED TUTT LOW WILL
ACROSS THE LOCAL ISLANDS FROM TIME TO TIME TO COMBINE WITH DAYTIME
HEATING AND GOOD UPPER LEVEL DYNAMIC TO IGNITE SHOWERS AND
THUNDERSTORMS EACH AFTERNOON FRIDAY THROUGH THE UPCOMING WEEKEND.
LOOKING WELL AHEAD...COMPUTER MODELS GUIDANCE SUGGEST THAT THE
TROPICAL ATLANTIC WILL BECOME ACTIVE DURING THE UPCOMING WEEKS AS
SEVERAL LOW PRESSURE SYSTEMS DEVELOP INTO TROPICAL CYCLONES. STAY
TUNED

&&

.AVIATION...EXCEPT FOR INTMT PERIODS OF PASSING CLDS AND TRADE WIND
SHOWERS EN ROUTE BTW THE NRN LEEWARDS AND PR....EXPECT PREVAILING
VFR CONDS AT THE LOCAL TAF SITES THROUGH 18/12Z. FM 18/06-18/12Z THE
PASSING SHOWERS MAY BRING TEMPO MVFR DUE TO LOW CLDS AND MODERATE
SHRA OVR AND VCTY TISX..TIST... TJNR... AND TJSJ. HOWEVER... EXPECT
THE MVFR CONDS TO BE OF SHORT DURATION. MTN TOP OBSCURE ALSO PSBL
ACROSS THE E SECTIONS OF THE CORDILLERA CENTRAL OF PR...PICO DEL
ESTE...DUE TO LOW CLDS AND PASSING SHRA. TKPK AND TNCM WILL ALSO
EXPERIENCE TEMPO MVFR DUE TO SHRA/LOW CIGS BTW 18/08Z-18/12Z.

&&

[msbee]

Good morning
Where is everyone?


Here is the latest CROWNWEATHER discussion:

Issued: Wednesday, August 18, 2010 550 am EDT/450 am CDT

For the Tropical Weather Discussion with Maps, Images and Graphics, Go To: http://www.crownweather.com/?page_id=325.


Discussion
All of the focus this morning is on the eastern Atlantic where a strong and robust tropical wave that is currently located over extreme western Africa will emerge into the far eastern Atlantic within the next 24 hours and will likely interact with another tropical wave now located just west of the Cape Verde Islands. This interaction is forecast to lead to the development of a tropical cyclone between Friday and Sunday. Environmental conditions are becoming increasingly more favorable as the tropical wave west of the Cape Verde Islands is moistening up the atmosphere as it travels westward. At the same time, a ridge of high pressure is building westward to the north of these two waves. This favorable environment will lead to the development of a tropical cyclone in the eastern Atlantic sometime between Friday and Sunday.

As should be expected, the model guidance varies wildly on the eventual track of this system. The latest GFS model is the furthest west and is the craziest. It forecasts a hurricane landfall on the entire Mid-Atlantic and Northeast US Coast around August 30th. The other model guidance has different tracks with the NOGAPS model forecasting a curve northward right into a ridge of high pressure which seems very unbelievable. The Canadian model also forecasts a curve northward around 50 West Longitude. The latest European model forecast is showing a curve out into the open Atlantic east of the Lesser Antilles in about 9 to 10 days. So, the GFS model is the lone model in forecasting a landfall on the United States.

The ensemble guidance and the operational model guidance do agree on some sort of East Coast trough of low pressure in about 10 days from now. The reason why the latest GFS model run is forecasting a hurricane landfall on the Mid-Atlantic and Northeast US is because it lifts that trough of low pressure out fairly quickly and builds a strong high pressure ridge just south of Nova Scotia which sets up an alley right into the Mid-Atlantic and Northeast US.
The recent trends and consistency of the European model of a curve out into the open Atlantic is hard to ignore, since this model does well in sniffing out patterns far before any other model. If you remember Hurricane Bill from last year, the GFS model consistently forecasted an East Coast hit while the European model was correct in Bill's final track. It should be noted, however, that the European model ensemble guidance continues to forecast a further southwest track and places this system very near the northernmost Leeward Islands in 9 days and near 22.5 North Latitude, 65.5 West Longitude in 10 days. So, it is not of the question that the operational European model may trend south and west over the next few days and this will be monitored.

So, I want to strongly emphasize that extreme discretion should be exercised when looking at individual model runs or the ensemble model guidance, especially when you reach more than a few days out. Little changes in the timing of troughs of low pressure and ridges of high pressure and how they interact with this system will significantly alter its final track.

So, what should you take away from this?? I think it seems likely that we will have a developing system in the far eastern Atlantic this weekend that seems likely to become a significant hurricane next week between the Lesser Antilles and the Cape Verde Islands. Folks in the Lesser Antilles, especially those northern islands should keep very close tabs on this system because if the ridge of high pressure over the eastern Atlantic ends up stronger than forecast, it would cause a more westward track and a real potential risk to you folks.

If this wasn't enough, quite a few of the model guidance, including the GFS, Canadian and NOGAPS models forecast a second system to start developing in the far eastern Atlantic in about a week from now and the very long range GFS model hints at a potential threat to the Lesser Antilles from this second system just before the Labor Day weekend.

The next tropical weather discussion will be issued by 7 am EDT/6 am CDT Thursday morning.

[msbee]

good morning Luis

Is the haze Saharan dust ? we have very hazy skies here today also.

[cycloneye]

good morning Luis

Is the haze Saharan dust ? we have very hazy skies here today also.

Yes,that is it.

[BZSTORM]

Good Afternoon everyone, quick question that large wave near haiti/jamaica anyone see on models if this is likely to dev into anything that might affect Belize in next week or so or even track over Belize as a wave? TBH I don't understand the model runs and have to wait till a system has plotted route for each computer model to understand them, if that makes sense. Were supposed to have had thunderstorms this morning on southern coast but so far nada here, last night lots of thunder and lightening & radar showed big storm coming in my direction in Placencia but never amounted to much just short shower and lot of wind.

[cycloneye]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
234 PM AST WED AUG 18 2010

.SYNOPSIS...A RELATIVELY DRIER AIR MASS WILL PREVAIL OVER THE LOCAL
REGION THROUGH THURSDAY AFTERNOON. A TUTT WILL APPROACH TO THE
REGION FROM THE EAST LATE THURSDAY AND FRIDAY INDUCING AGAIN AN
INCREASE IN MOISTURE ACROSS THE REGION.

&&

.DISCUSSION...HAZY SKIES HAVE DOMINATED THE LOCAL AREA TODAY AS
SAHARAN DUST HAS MOVED BEHIND THE TROPICAL WAVE. THIS DRIER
AIR MASS WILL PREVAIL OVER THE REGION THROUGH AT LEAST THURSDAY
AFTERNOON. A TUTT LOW NOW LOCATED AT AROUND 18N AND 58W...WILL
MOVE WEST FOR THE NEXT 48 HOURS. ON FRIDAY THIS WEATHER FEATURE
WILL BE LOCATED NORTH OF OR LOCAL FORECAST AREA ENHANCING SHOWERS
AND THUNDERSTORMS DEVELOPMENT. SATURDAY WILL BE A TRANSITION DAY
AS LINGERING MOISTURE WILL BE AVAILABLE TO GENERATE AFTERNOON
CONVECTION ACROSS THE WESTERN PORTIONS OF PUERTO RICO. SUNDAY WILL
BE A QUIET WEATHER DAY AS STABLE CONDITIONS WILL PREVAIL ACROSS
THE REGION. NEXT SIGNIFICANT TROPICAL WAVE WILL BE REACHING OUR
LOCAL WATERS EARLY MONDAY.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL ACROSS MOST OF THE TAF SITES
THROUGH THE FORECAST PERIOD. SOME PASSING SHOWERS OR VCSH ARE
POSSIBLE ACROSS TISX AND TJBQ DURING THE REST OF THE AFTERNOON
HOURS. HOWEVER...TEMPO MVFR CONDS AND MTN TOP OBSCURATION WILL OCCUR
ACROSS WESTERN AND INTERIOR SECTIONS OF PR...MAINLY OVER TJMZ AND
VICINITY...DUE TO LOW CLDS AND PASSING SHRA/TSRA.

&&

.MARINE...SEAS WILL BEGIN TO SUBSIDE TONIGHT AS WINDS ALSO
CONTINUE TO DECREASE TONIGHT. MARINERS AND BEACH GOERS SHOULD
EXPECT SEAS BETWEEN 3 TO 5 FEET AND WINDS BETWEEN 15 TO 20 KNOTS