INVEST 99L near Leewards,comments,sat pics,etc #4

[bvigal]

Wow! I just spent 20 minutes wading through all these posts to try and figure out what is going on!

Here, let me put it this way: You live where I do, and you own a boat which is how you make your living, plus it is your home. What odds does everyone here give you that in less than in 36 hrs you are going to be slammed with 50kt-wind tropical storm??? 1%, 5%, 10%, higher? Forget the U.S. mainland and cat 5 hurricanes for one second, just how much organizing is it going to do before reaching 64W?

I think it will probably get pretty squally there in the VI tomorrow. What's SJU forecasting for y'all?

4pm NWS/SJU:
MARINE CONDITIONS HAVE BEEN IMPROVING THROUGH THE DAY. THE NEXT
TROPICAL WAVE WAS EAST OF THE WINDWARD ISLANDS OR AROUND 350 MILES
SOUTHEAST OF THE U.S. VIRGIN ISLANDS THIS AFTERNOON. THIS TROPICAL
WAVE IS ELONGATED SOUTHWEST TO NORTHEAST...AND WILL AFFECT THE LOCAL
WATERS TOMORROW NIGHT THROUGH WEDNESDAY BRINGING ACTIVE
WEATHER...AND INCREASING WINDS AND SEAS.

*rather disturbing they haven't noticed this area has split off from the wave.

[bvigal]

Wow! I just spent 20 minutes wading through all these posts to try and figure out what is going on!

Here, let me put it this way: You live where I do, and you own a boat which is how you make your living, plus it is your home. What odds does everyone here give you that in less than in 36 hrs you are going to be slammed with 50kt-wind tropical storm??? 1%, 5%, 10%, higher? Forget the U.S. mainland and cat 5 hurricanes for one second, just how much organizing is it going to do before reaching 64W?

I think it will probably get pretty squally there in the VI tomorrow. What's SJU forecasting for y'all?

So, no development, no closed low, no TD or TS, right?

[Air Force Met]

I use the definition of a low-pressure center to include a closed circulation. That is what I refer to as a low center

...and I use a different definition. The low for us is at least one closed isobar. When you get that one little area that is of lower pressure moving over water...when the frictional force is not that great to cause the backing...and your PGF also isn't that great...you may or may not have a closed circulation because the stupid thing is moving at 20 knots. Remember all the recon drops with 1008 mb pressures surround by 1009's and 1010's...but they can't close off a circulation.

[cycloneye]

Wow! I just spent 20 minutes wading through all these posts to try and figure out what is going on!

Here, let me put it this way: You live where I do, and you own a boat which is how you make your living, plus it is your home. What odds does everyone here give you that in less than in 36 hrs you are going to be slammed with 50kt-wind tropical storm??? 1%, 5%, 10%, higher? Forget the U.S. mainland and cat 5 hurricanes for one second, just how much organizing is it going to do before reaching 64W?

I think it will probably get pretty squally there in the VI tomorrow. What's SJU forecasting for y'all?

Tony,here is the discussion from San Juan NWS.


000
FXCA62 TJSJ 311958
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
358 PM AST MON JUL 31 2006

.SYNOPSIS...AT UPPER LEVELS...A RIDGE OF HIGH PRESSURE WILL
CONTINUE OVER THE AREA THROUGH TUESDAY...ON WEDNESDAY THROUGH
FRIDAY A LOW PRESSURE SYSTEM WILL APPROACH THE ATLANTIC WATERS
JUST TO THE NORTH OF PUERTO RICO AND MOVE NORTHWEST. HIGH PRESSURE
WILL THEN RIDGE IN FROM THE NORTHEAST OVER THE FOLLOWING WEEKEND.

AT MID LEVELS...WEAK HIGH PRESSURE CENTERED NORTH OF THE U.S.
VIRGIN ISLANDS WILL FORM A RIDGE TO THE NORTHWEST AND JOIN A HIGH
PRESSURE CENTER OVER TENNESSEE BY WEDNESDAY NIGHT. ON WEDNESDAY A
WEAK LOW PRESSURE EAST OF PUERTO RICO NEAR 56 WEST WILL MOVE WEST
AND CROSS BETWEEN PUERTO RICO AND THE U.S. VIRGIN ISLANDS LATE ON
FRIDAY AS CURRENTLY FORECAST. HIGH PRESSURE FROM THE ORIGINAL HIGH SYSTEM
WILL THEN RIDGE BACK INTO THE AREA FROM THE NORTH OVER THE
WEEKEND.

AT LOWER LEVELS...A TROPICAL WAVE WHOSE AXIS STRETCHES FROM 18
NORTH 55 WEST TO 12 NORTH 61 WEST IS MOVING AT ABOUT 18 KNOTS TO
THE WEST NORTHWEST AND WILL ENTER THE CARIBBEAN EARLY TUESDAY WITH
WEATHER BEGINNING TO AFFECT SAINT CROIX AROUND SUNSET TUESDAY.
THIS SYSTEM IS EXPECTED TO MOVE OVER PUERTO RICO TUESDAY NIGHT
WITH MOIST AIR AFFECTING THE LOCAL AREA THROUGH WEDNESDAY NIGHT.
THE NEXT WAVE WILL MOVE INTO THE CARIBBEAN SEA ON MONDAY BY
CURRENT PROJECTIONS AND MAY BE MORE DEVELOPED THAN THE CURRENT WAVE.


&&

.DISCUSSION...850 MB WINDS AND MOISTURE WITH THE NEXT TROPICAL
WAVE DO NOT LOOK AS STRONG AS THE WAVE THAT JUST PRECEDED IT.
ALTHOUGH STRONG CURVATURE IS PRESENT IN THE WINDS OF THE NEXT WAVE
AT THIS LEVEL...WINDS GO FROM 060 TO ALMOST 180 IN TWELVE HOURS
OVER PUERTO RICO...THE STRONGEST VELOCITIES FORECAST ARE BUT 25
KNOTS AS OPPOSED TO SPOTS OF 50 KNOTS WITH THE PREVIOUS WAVE. ALSO
CURRENT CONVECTION TO THE EAST OF THE WAVE IS LIMITED. NEVERTHELESS
THE PRESENCE OF GOOD MOISTURE...AT LEAST IN LOWER LAYERS...SHOULD
BE SUFFICIENT FOR ACTIVE WEATHER BEGINNING TUESDAY NIGHT AND
CONTINUING INTO WEDNESDAY. MODELS SUGGEST A SLIGHT BREAK BEFORE
BETTER MOISTURE RETURNS WEDNESDAY NIGHT. AFTER THIS... MOISTURE IS
GOOD BUT NOT EXCEPTIONALLY HIGH FROM FRIDAY NIGHT TO SUNDAY
EVENING. MOISTURE INCREASES WITH THE NEXT SYSTEM IN THE
MODEL...BUT THERE IS MUCH MORE UNCERTAINTY REGARDING THE WEATHER
TO BE HAD AROUND IT BECAUSE THE AMOUNT OF DEVELOPMENT IS NOT YET
CLEAR. AREAS JUST BEFORE AND AFTER THIS SYSTEM COULD BE MUCH DRIER
IF IT BECOMES STRONGER OR DEVELOPS INTO A TROPICAL CYCLONE BEFORE
APPROACHING. AND IF IT DOES SO WINDS AND RAINS FELT IN PUERTO RICO
AND THE U.S. VIRGIN ISLANDS WOULD BE STRONGER...BUT ALSO MORE
DEPENDENT ON ITS POSITION AND TIMING.

[AJC3]

Wow! I just spent 20 minutes wading through all these posts to try and figure out what is going on!

Here, let me put it this way: You live where I do, and you own a boat which is how you make your living, plus it is your home. What odds does everyone here give you that in less than in 36 hrs you are going to be slammed with 50kt-wind tropical storm??? 1%, 5%, 10%, higher? Forget the U.S. mainland and cat 5 hurricanes for one second, just how much organizing is it going to do before reaching 64W?

I think it will probably get pretty squally there in the VI tomorrow. What's SJU forecasting for y'all?

So, no development, no closed low, no TD or TS, right?

On the contrary, I think it WILL close off within 24 hours. I'd think the system will be a TD or low-end TS as it passes by your area.

[Air Force Met]

So, no development, no closed low, no TD or TS, right?

I think we are getting close. I think the TWO at 5:30 will say something about it being close or that a weak LLC has developed.

[cycloneye]

SURFACE OBSERVATIONS INDICATE THAT A WEAK CIRCULATION HAS DEVELOPED
IN THE TROPICAL WAVE LOCATED ABOUT 200 MILES EAST OF THE LEEWARD
ISLANDS. THE ASSOCIATED SHOWER ACTIVITY REMAINS LIMITED AND
ENVIRONMENTAL CONDITIONS ARE ONLY MARGINALLY FAVORABLE FOR
ADDITIONAL DEVELOPMENT...HOWEVER...ONLY A SMALL INCREASE IN
ORGANIZATION WOULD RESULT IN THE FORMATION OF A TROPICAL
DEPRESSION. WHETHER OR NOT A TROPICAL DEPRESSION DEVELOPS...
LOCALLY HEAVY SHOWERS AND OCCASIONAL STRONG GUSTY WINDS ARE LIKELY
OVER PORTIONS OF THE LESSER ANTILLES DURING THE NEXT DAY OR TWO AS
THIS SYSTEM MOVES TO THE WEST-NORTHWEST AT ABOUT 15 MPH.


5:30 PM TWO.

[Ivanhater]

I love the tropics, things change so fast!

[Derek Ortt]

...and I use a different definition. The low for us is at least one closed isobar. When you get that one little area that is of lower pressure moving over water...when the frictional force is not that great to cause the backing...and your PGF also isn't that great...you may or may not have a closed circulation because the stupid thing is moving at 20 knots. Remember all the recon drops with 1008 mb pressures surround by 1009's and 1010's...but they can't close off a circulation.

I perfer calling that an area of low-pressure

Its all semantics though

[Extremeweatherguy]

Possible TD classification at 11pm?

[Grease Monkey]

Why not 8pm?

[Swimdude]

AHH SO CLOSE.

Stupid TWO. This is killing us!

[HurricaneHunter914]

http://cimss.ssec.wisc.edu/tropic/real- ... wg8sht.GIF

Wow, the shear just went kinda neutral in the tropics with mostly low shear.

[Air Force Met]

So, no development, no closed low, no TD or TS, right?

I think we are getting close. I think the TWO at 5:30 will say something about it being close or that a weak LLC has developed.

Bing bing. Speak of the devil.

[Extremeweatherguy]

http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8sht.GIF

Wow, the shear just went kinda neutral in the tropics with mostly low shear.

If this takes the Caribbean route, then it looks like it could become fairly strong, but if it takes a more northern route, this will probably stay a TD or weak TS through the next few days.

[benny]

Highly unlikely that those NW winds are due to a tstm since all the tstms are on the east side.. outflows would tend to shoot away from the system, not toward the center of it. This looks like the outer part of the wannabe cyclone circulation to me. Unfortunately it is hard with a small fast-moving system to see much veering with hourly reports. If it is still westerly next hour.. i will be very interested though as it seems to have gotten its act together in a big way today.

I'm not a big fan of streamlines as they tend to not be particularly useful unless you have a lot of data and don't have to make up the streamlines.. ie like this system with a few observations.

Well...there is a big TSTM just to the north of the buoy and the vort center is to the NW of the buoy. Go to the GHCC and see for yourself. Since the vrt center is NW of the TSTMS are east...then that means they are over the buoy. Right? Either way...when there are TSTMS in the area and the windfield is light...it contaminates the flow.

As far as streamlines go and you not being a fan of them...that means you have never been a forecater in an area with limited data...plain and simple. For one thing...there are plenty of cloud elements to analyze the cusp...which is how this is being analyzed...not on the basis of a couple of buoys. Second, streamline analysis is bread and butter for forecasters in the tropics with limited data. You don't have to have actual hard data points from buoys or ships to do a streamline chart. When I was in central america...I used sfc data+model data to prepare my streamlines...and only model data to produce my upper level streamlines (250mb)...since there was very little upper air data. If you don't use streamlines in the tropics to help you forecast...you are sunk.

And you will bust your forecast. That is the hard core facts...which is the reason so many new forecasters have a hard time forecasting in the tropics. You don't have a lot of data...and that is EXACTLY where streamlines come in. You don't need ships...you can use satellite and model data to offset that gap...if you know what you are doing.

We'll just have to disagree about the TSTM related wind. I don't think so and I see little evidence of it on satellite. As far as the streamlines.. as someone with forecast experience in the tropics... I've never seen any use for them. Of course I suppose what it is you are forecasting makes all the difference in the world. Everyone in the Pacific loves the streamlines but I personally can't stand them. A person can invent something with satellite if you like but ... as for as TCs go.. they don't really illustrate a whole lot unless you have data.. and not just satellite. But if you find the streamlines useful.. go for it! Some people can't live without them and I'm not sure why.

[Derek Ortt]

as small as this developing circulation is, it had better stay away from Hispaniola if it wants to survive

[NDG]

So, no development, no closed low, no TD or TS, right?

I think we are getting close. I think the TWO at 5:30 will say something about it being close or that a weak LLC has developed.

Bing bing. Speak of the devil.

Good call, I didn't think they were going to go that far in mentioning a developing LLC.

[Air Force Met]

http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8sht.GIF

Wow, the shear just went kinda neutral in the tropics with mostly low shear.

That's the tendancy chart....not the shear itself.

[HurricaneHunter914]

I think 99L has finally found his chance to become a TD.