Global model runs discussion

[jlauderdal]

Miami NWS coming around to a wetter solution...looks like a long period of crappy weather.


LONG TERM...SATURDAY THROUGH MONDAY
LONG RANGE GUIDANCE CONTINUE TO INDICATE A KIND OF HYBRID CYCLONE
DEVELOPMENT ALONG THE OLD FRONTAL BOUNDARY EXTENDING FROM CUBA
THROUGH THE BAHAMAS. ECMWF SHOWS DEVELOPMENT MORE TO THE WEST
OF S. FLORIDA IN THE GULF OF MEX WHILE GFS NOW SHOWS A WEAK
DEVELOPMENT FURTHER EAST AND LATER (MONDAY) OVER THE NORTHERN
BAHAMAS. THERE IS LARGE UNCERTAINTY AT THIS TIME WHETHER EITHER OF
THESE SCENARIO WILL DEVELOP...HOWEVER BOTH MODELS AGREE WE WILL
REMAIN UNDER A PERSISTENT STRONG LOW LEVEL EAST FLOW AND BOTH
MODEL SHOW A SIGNIFICANT INCREASE IN THE CHANCES FOR RAIN AND EVEN
THE POTENTIAL FOR HEAVY RAIN. DECIDED TO INCREASE POPS AT LEAST
THROUGH FIRST PART OF THE LONG RANGE PERIOD TO ACCOUNT FOR THE
CONTINUITY AND PERSISTENCE IN THE MODELS. THIS SITUATION SHOULD BE
CLOSELY MONITORED DURING THE NEXT MODEL RUNS AS CONFIDENCE WILL
LIKELY INCREASE IF MODEL CONTINUE WITH THIS TREND.

[cycloneye]

This afternoon's discussion of potential development and weather related by the Tallahassee NWS.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
250 PM EDT WED OCT 5 2011

.LONG TERM...(FRIDAY THROUGH NEXT TUESDAY).
MAIN CONCERN IN THE LONG TERM PERIOD IS ONCE AGAIN FOCUSED AROUND
THE POTENTIAL FOR THE FORMATION OF SOME SORT OF SUBTROPICAL LOW IN
THE VICINITY OF FLORIDA. MODELS CONTINUE TO SHOW A LACK OF RUN TO
RUN CONSISTENCY...WITH THE ECMWF TENDING TO BE THE MOST CONSISTENT
MODEL OVER THE PAST SEVERAL DAYS. IT SHOULD ALSO BE NOTED THAT THE
ECMWF WAS ONE OF THE FIRST MODELS TO DEVELOP SUCH A LOW...AND FOR
NOW IT SEEMS TO BE PRESENTING ONE OF THE MORE CREDIBLE SOLUTIONS.

THE MECHANISMS FOR THE GENESIS OF THIS SUBTROPICAL LOW (AS FORECAST
BY THE NUMERICAL MODELS) REMAIN BASICALLY UNCHANGED FROM LAST NIGHT.
CONVECTION IS ONGOING IN FAIR ABUNDANCE ALONG THE QUASI-STATIONARY
FRONT THAT IS DRAPED ACROSS THE BAHAMAS AND WSW TOWARDS THE YUCATAN
STRAIT. THE TSTMS IN THE BAHAMAS AND FLORIDA STRAITS ARE ALSO IN THE
RIGHT ENTRANCE REGION OF A 60-80 KT UPPER LEVEL JET THAT CURLS NORTH
AROUND THE PERSISTENT UPPER LOW IN THE NE CONUS. THIS IS EXPECTED TO
CONTINUE IN SOME FORM THROUGH THURSDAY...WITH SLOWLY FALLING SURFACE
PRESSURE AND MID-UPPER LEVEL HEIGHTS. BY THE WEEKEND MODELS FORECAST
MORE SIGNIFICANT CHANGES TO TAKE PLACE WITH A CLOSED SURFACE LOW
DEVELOPING SOMEWHERE INITIALLY BETWEEN 20N AND 25N. THE AREA WILL
REMAIN SQUARELY WITHIN THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL
JET STREAK...AND SEVERAL SHORTWAVES PUSHING INTO THE AREA WILL HAVE
CONTRIBUTED TO A BROAD AREA OF LOWER HEIGHTS AND CYCLONIC FLOW IN
THE MID LEVELS. BASICALLY THERE WILL BE A HANDFUL OF FACTORS
FAVORING LARGE SCALE ASCENT AND THE MAINTENANCE OF ANY CONVECTIVE
CLUSTERS. PINPOINTING THE AREA WHERE THINGS COME TOGETHER MOST
FAVORABLY IS RATHER DIFFICULT AT THIS JUNCTURE. THE OVERALL FORECAST
IS FOR THE GENESIS OF A SUBTROPICAL LOW THIS WEEKEND...WITH A SLOW
MIGRATION TO THE NW AND EVENTUALLY NORTH.

CHANGES TO THE GRIDS INVOLVED A SLIGHT BOOST IN POPS AFTER SATURDAY
NIGHT AS MODELS...ALTHOUGH INCONSISTENT...HAVE SHOWN A GENERAL
WESTWARD TREND WITH THE LOCATION OF THE LOW. DIURNAL TEMPERATURE
RANGES WERE KEPT LOWER IN THE EASTERN HALF OF THE CWA...WITH HIGHER
DEWPOINTS...RH...AND CLOUD COVER.

THE HPC PRELIMINARY EXTENDED FORECAST DISCUSSION ONCE AGAIN OFFERS
GOOD ANALYSIS OF THIS SYSTEM...AND OFFERS SEVERAL ANALOGS TO PAST
CASES. THE BEST ANALOG IN TERMS OF THE RESEMBLANCE TO FORECAST
PRESSURE AND HEIGHT PATTERNS SEEMS TO BE THE MAY 19-21 2009 GULF
LOW...WITH THINGS IN THIS CASE PERHAPS SHIFTED SLIGHTLY EAST. ONE
THING THAT WAS NOT PRESENT IN THAT EVENT WAS 28-30C WATER TEMPS
WHICH COULD AID THE GENESIS AND ORGANIZATION OF THE LOW THIS TIME.

[Ivanhater]

Both the GFS and Euro show a tropical storm headed for the Florida Panhandle.

[Dean4Storms]

It has my attention!!

[Rainband]

Both the GFS and Euro show a tropical storm headed for the Florida Panhandle.

being i will be on the east of this I am watching closely

[ROCK]

one thing is for sure Hybrid or not there is plenty of warm water in the GOM....

http://wxmaps.org/pix/hurpot.html#ATL

never seen it that hot in Oct...

[ROCK]

the 18z NOGAPS isjacked up as always.....interesting is the 12Z CMC showing 2 lows in the GOM...seems odd as well....

[Rainband]

the 18z NOGAPS isjacked up as always.....interesting is the 12Z CMC showing 2 lows in the GOM...seems odd as well....

link

[shortwave]

lots of rain. nice to see the miami bureau grudgingly climb aboard.
lots of dry air could shove precipts further east and north

[northjaxpro]

Both the GFS and Euro show a tropical storm headed for the Florida Panhandle.

being i will be on the east of this I am watching closely

Yes, I will be monitoring this possible development as well.

[bigdan35]

ukmet picking up on it




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[SootyTern]

one thing is for sure Hybrid or not there is plenty of warm water in the GOM....

http://wxmaps.org/pix/hurpot.html#ATL

never seen it that hot in Oct...

Lots of fuel for a storm taking a Wilma-like track. I'm surprised the northern Gulf is still running so hot, too.

[floridasun78]

ok sorry that was old one no new update yet mostly like we wont see one untill 3am but all weatherman starting see models run that show rainy weekend

[floridasun78]

right now we dont have storms in nw carribbean yet

[MGC]

The NGOM has cooled quite a bit the past several days. Bouy 42067, just south of the Mississippi Coast is reporting a SST of 78.4F as of today. The cold front that dropped our temperature into the upper 40's the past couple of mornings has worked magic on gulf temps......MGC

[Rainband]

one thing is for sure Hybrid or not there is plenty of warm water in the GOM....

http://wxmaps.org/pix/hurpot.html#ATL

never seen it that hot in Oct...

Lots of fuel for a storm taking a Wilma-like track. I'm surprised the northern Gulf is still running so hot, too.

not sure that will happen

[AdamFirst]

The NGOM has cooled quite a bit the past several days. Bouy 42067, just south of the Mississippi Coast is reporting a SST of 78.4F as of today. The cold front that dropped our temperature into the upper 40's the past couple of mornings has worked magic on gulf temps......MGC

At the immediate coast maybe...it's still a cauldron in the Gulf. It's cooking.

[SootyTern]

one thing is for sure Hybrid or not there is plenty of warm water in the GOM....

http://wxmaps.org/pix/hurpot.html#ATL

never seen it that hot in Oct...

Lots of fuel for a storm taking a Wilma-like track. I'm surprised the northern Gulf is still running so hot, too.

not sure that will happen

I know not from this event forecast for the weekend; it was just a general observation

[KUEFC]

Just out of interest, just been reading the NWS melbourne discussion today, what does PENDERGRAST, and LASCODY refer to in the aviation section? aviation is a general interest of mine and this is probably the wrong part of the forum to ask this, but can anyone tell me?

[ronjon]

Good AFD from NWS Tallahassee on the subtropical low.

.LONG TERM (SATURDAY THROUGH NEXT WEDNESDAY)...
THE EXTENDED FORECAST IS BEGINNING TO COME INTO A LITTLE BETTER
FOCUS AS MOST GLOBAL MODELS ARE CONVERGING CLOSER TO THE ECMWF
SOLUTION REGARDING THE SUBTROPICAL LOW THAT IS FORECAST TO DEVELOP.
THE 04.12Z AND 05.00Z RUNS OF THE ECMWF HAVE BEEN CONSISTENT WITH
PRODUCING A WEAK CLOSED SURFACE LOW (AROUND 1007 MB) NEAR THE
WESTERN TIP OF CUBA AND THE FLORIDA STRAITS...AND THEN SLOWLY
DEEPENING THE LOW AS IT PUSHES NORTH TO NEAR APALACHICOLA BY LATE
TUESDAY. HIGHER CONFIDENCE WAS PLACED IN THE ECMWF THE LAST SEVERAL
RUNS DUE TO ITS BETTER CONSISTENCY WITH THIS FEATURE...AND THAT
CONTINUES TO BE THE CASE. THEREFORE...THE EXTENDED FORECAST WAS
WEIGHTED ABOUT TWO-THIRDS 00Z ECMWF...AND ONE-THIRD 00Z GFS WHICH
HAS MOVED MUCH CLOSER TO THAT SOLUTION. THE FACT THAT THE 05.00Z GFS
ENSEMBLE MEAN IS VERY SIMILAR TO THE EUROPEAN MODEL LENDS MORE
CONFIDENCE TO THE FORECAST THAN THE PAST TWO NIGHTS.

OBVIOUSLY...THE WESTWARD TREND IN THE MODELS OVER THE PAST 24-48
HOURS PLACES THE TAE CWA MORE IN LINE FOR THE HEAVIER AXIS OF
PRECIPITATION WITH ANY SUCH LOW THAT WOULD BE TRACKING NORTH. THE
GFS ENSEMBLE MEAN PLACES NEARLY 3.5 INCHES OF RAIN JUST SOUTH OF
APALACHICOLA BY WEDNESDAY AFTERNOON...AND 2 INCHES ACROSS OUR
SOUTHEAST. WITH INCREASING MODEL SUPPORT FOR RAIN...POPS WERE NUDGED
UP ANOTHER 5 TO 10 PERCENT BEYOND THIS WEEKEND.

THE EVOLUTION OF THIS LOW IS STILL VERY INTERESTING. AS THE PRESSURE
AND HEIGHT FALLS TAKE PLACE AROUND THE FLORIDA STRAITS INTO THE
WEEKEND...THAT AREA WILL BE IN SOMEWHAT OF A COUPLED JET STRUCTURE
AND CERTAINLY IN THE RIGHT ENTRANCE REGION OF A 60-70 KT UPPER LEVEL
JET. THERE WILL BE HORIZONTAL TEMPERATURE AND THICKNESS GRADIENT
FROM NORTH-SOUTH ACROSS THE DEVELOPING LOW. THEREFORE ITS ORIGINS
WILL NOT BE TROPICAL IN NATURE. AND YET...AS THE LOW DEVELOPS...THE
ECMWF/GFS MODEL SOLUTIONS SHOW INCREASING TROPICAL CHARACTERISTICS.
BY MONDAY-TUESDAY THEY INDICATE MORE OF A WARM CORE STRUCTURE...WITH
SLIGHTLY HIGHER 1000-500MB THK AT THE CENTER OF THE VERTICALLY
STACKED CIRCULATION...AND THERMAL WIND VECTORS IN THE SAME LAYER
WRAP AROUND THE LOW IN A CLOCKWISE FASHION. THE LOW WILL BE PASSING
OVER WATER THAT HAS SEA SURFACE TEMPERATURES STILL 29-30C...AND
850-300MB BULK SHEAR OVER MUCH OF THE EASTERN GULF DROPS TO AROUND
5-10 KNOTS BY MONDAY. BOTH ARE INDICATIVE OF FAVORABLE CONDITIONS
FOR TROPICAL DEVELOPMENT. CERTAINLY...THIS LOW WILL BE ONE TO KEEP
AN EYE ON...EVEN IF IT ONLY ATTAINS SUBTROPICAL STATUS. AT THE VERY
LEAST IT SHOULD BE A BREEZY AND WET START TO THE NEXT WORK WEEK.