Watching for Subtropical Development

Anonymous · #1 Postby **Anonymous** » Sun Apr 13, 2003 9:42 pm

As Bob has been mentioning over the last couple days, the models are showing the development of a weak low pressure system over the Bahamas. A low could develop along a stalled front near the Dominican Republic. The low will likely track northeast along the front. But there is a slight chance that the low pressure center could move more westerly IF a high building over eastern Canada moves east soon enough. But a NE track out to sea would be the most likely scenario. Chances of subtropical development are low...but of course should be monitored.

#2 Postby **wx247** » Sun Apr 13, 2003 9:49 pm

Thanks for the info. It bears watching!

#3 Postby **cycloneye** » Sun Apr 13, 2003 9:54 pm

http://www.srh.noaa.gov/data/sju/AFD/SJUAFDSJU.1.txt

But only it mentions the low a little but the discussion says that a low will form north of PR.

ColdFront77 · #4 Postby **ColdFront77** » Mon Apr 14, 2003 2:30 am

I agree, Garrett, it bears watching.

As TropicalWxWatcher indicates, with the low chance of this low pressure system developing into a subtropical storm and current prognostications have it moving NE, out to sea.

The more of these we see in the next 16 to 31 days, we may see an increase chance in development in late May.

We shall see...

chadtm80 · #5 Postby **chadtm80** » Mon Apr 14, 2003 8:17 am

000
FXCA62 TJSJ 140915
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
516 AM AST MON APR 14 2003

ELONGATED MID TO UPPER LEVEL RIDGE WILL REMAIN THE MAIN WEATHER
FEATURE LOCALLY INTO TUESDAY...THEN HEIGHTS GRADUALLY LOWER TUESDAY
THROUGH THURSDAY...AND THEN CHANGE LITTLE FRIDAY...AS TROFFINESS
APPROACHES FROM THE WEST-NORTHWEST AND THEN LINGERS TO OUR WEST AND
NORTHWEST INTO THE UPCOMING WEEKEND. UPPER LEVEL SHORT WAVE NEAR
JAMAICA AT THIS TIME WILL MOVE NORTHEAST TODAY AND TONIGHT...PASSING
MAINLY NORTH OF THE FA. HOWEVER ASSOCIATED 50 KNOT 250 MB WIND MAX
WILL PASS NEAR OR ACROSS LOCAL ISLANDS TODAY AND THIS SHOULD ENHANCE
AFTERNOON CONVECTION LOCALLY. IN GENERAL...AS HEIGHTS LOWER...NOT A
WHOLE LOT OF DYNAMICS UNTIL LATE THURSDAY OR FRIDAY...OTHER THAN
PASSING UPPER LEVEL PERTURBATIONS...SO STILL LOOKS LIKE MAINLY
DIURNALLY/NOCTURNALLY INDUCED SHOWERS AND ISOLATED THUNDERSTORMS
DURING THE TUESDAY THROUGH THURSDAY TIME FRAME.

FOR TODAY AND TONIGHT...SATELLITE SHOWING SOME MOISTURE (CLOUDS)
MOVING WEST INTO/ACROSS LOCAL ISLANDS AT THIS TIME AND ENOUGH OF
THIS SHOULD LINGER TO COINCIDE AGAIN WITH DAYTIME HEATING...AND
COMBINE WITH OTHER LOCAL EFFECTS AND AFOREMENTIONED UPPER LEVEL WIND
MAX...TO MAKE FOR SCATTERED TO NUMEROUS AFTERNOON SHOWERS AND
ISOLATED THUNDERSTORMS...MAINLY OVER CENTRAL AND WESTERN INTERIOR
AND NORTHWEST SECTIONS OF PUERTO RICO. ELSEWHERE...ISOLATED TO
SCATTERED...MAINLY BRIEF SHOWERS ARE EXPECTED.

FOR COASTAL WATERS...FAIRLY TRANQUIL CONDITIONS EXPECTED TO CONTINUE
THROUGH AT LEAST TUESDAY NIGHT AND PROBABLY BEYOND...WITH THE WIND
MOSTLY 15 KNOTS OR LESS AND SEAS 4 FEET OR LESS.

.SJU...
.PR...NONE.
.VI...NONE.

EQUIPMENT: NO PROBLEMS AT THIS TIME.

SEELEY

chadtm80 · #6 Postby **chadtm80** » Mon Apr 14, 2003 8:19 am

Anonymous · #7 Postby **Anonymous** » Mon Apr 14, 2003 5:42 pm

The models are showing a slightly stronger low prssure center today.

Anonymous · #8 Postby **Anonymous** » Mon Apr 14, 2003 5:47 pm

Stormsfury · #9 Postby **Stormsfury** » Mon Apr 14, 2003 7:09 pm

Check out the UKMET animation - it actually stalls this low ...

UKMET Sea Level Pressure Animation Loop

chadtm80 · #10 Postby **chadtm80** » Mon Apr 14, 2003 7:12 pm

Interesting Stormsfury

Anonymous · #11 Postby **Anonymous** » Mon Apr 14, 2003 7:18 pm

Check out the UKMET animation - it actually stalls this low ...

UKMET Sea Level Pressure Animation Loop

The UKMET appears to be overdeveloping the ridge. If the low were to stall, it would likely stall near the maritimes.

chadtm80 · #12 Postby **chadtm80** » Mon Apr 14, 2003 7:30 pm

The UKMET appears to be overdeveloping

well, surprise surprise surprise

ColdFront77 · #13 Postby **ColdFront77** » Mon Apr 14, 2003 7:40 pm

At least it is something for us to watch, no matter what happens to it. It could stall and lower pressure today is the start of development as we all no, no matter when and if the pressure rises.

Anonymous · #14 Postby **Anonymous** » Mon Apr 14, 2003 7:40 pm

well, surprise surprise surprise

Not the low!

#15 Postby **cycloneye** » Mon Apr 14, 2003 7:55 pm

No surprise chad

chadtm80 · #16 Postby **chadtm80** » Mon Apr 14, 2003 8:00 pm

I know cyc.. That was a lil joke of mine... Guess it failed... LOL

ColdFront77 · #17 Postby **ColdFront77** » Mon Apr 14, 2003 8:01 pm

What is the UKMET overdeveloping, then? It doesn't seem like this is clear to everyone here.

Stormsfury · #18 Postby **Stormsfury** » Mon Apr 14, 2003 8:27 pm

The NOGAPS keeps the system progressive and moves the low NE ... the CANADIAN doesn't go out far enough ...

What I believe TWW is stating is that the UKMET is trying to overamplify a North Atlantic Ridge (which incidentally indicates a strong CAD episode along the east side of the Appalachians) ... If anything, THE UKMET does have a known bias to overamplify things ...

However, I offer this ...
The EC also develops a strong high coming out of Eastern Canada as well, 1039 mb on Day 3 and 4, and strengthens it to 1041mb by Day 5. However, the low also is much further north than the UKMET...and more in line with the NOGAPS and the GFS ...

Right now, in regards to the UKMET, the model is the M.O. - wait another run or two ... the M.O. is going to be determined if the UKMET is the Model Outlier or if the Model is On to something. If the EC/GFS/NOGAPS/Canadian begin to trend towards the UKMET, then the M.O. is Model may be On to something. However, in regards to US Weather, I prefer the blend of the ECMWF/UKMET in regards to the CAD regime pattern along the East ... where for once, the UKMET IMO is overdoing the ridging down the East Coast, but not enough by the rest of the global models ... thus the low should be further north than the UKMET shows, but not quite as far north as the NOGAPS. Thus the GFS/ECMWF solution blend seems reasonable, though I do not like the GFS's handling of CAD events whatsoever along the East Coast.

Hope this helps

Anonymous · #19 Postby **Anonymous** » Mon Apr 14, 2003 10:41 pm

The UKMET overdeveloping (amplifying) the ridge had more to do with the track instead of intensity. My reply had nothing to do with the development of the low.

Anonymous · #20 Postby **Anonymous** » Mon Apr 14, 2003 10:41 pm

000
AXNT20 KNHC 142356
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON 14 APR 2003

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...AND ATLANTIC OCEAN
TO THE AFRICAN COAST FROM THE EQUATOR TO 32N INCLUDING NORTHERN
SECTIONS OF SOUTH AMERICA. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

MIDDLE/UPPER LEVEL SYNOPTIC FEATURES...
THE FOCUS OF THE WESTERN PART OF THE REGION IS A MID/UPPER LEVEL
LOW E OF JACKSONVILLE FLORIDA NEAR 30N77W MOVING SLOWLY
EASTWARD. THIS LOW HAS AN ATTENDANT TROUGH SSW ACROSS THE NW
BAHAMAS AND CUBA INTO THE NW CARIBBEAN SEA INTO N CENTRAL
HONDURAS. GOOD UPPER-LEVEL DIVERGENCE IS OVER THE ATLC N OF 24N
BETWEEN 61W-68W IN RIGHT-REAR QUADRANT OF JET. MOST MODELS ARE
NOW INDICATING A WEAK LOW TO FORM ON THE STATIONARY FRONT IN THE
W ATLC IN ABOUT 36 HOURS. SECOND WEAK DISTURBANCE OVER THE N
CENTRAL GULF OF MEXICO SHOULD AMPLIFY A BIT WITH ANOTHER TROUGH
EXPECTED OVER THE E GULF AND EXTREME NW CARIBBEAN IN NEXT 12-24
HOURS. MODERATE SUBSIDENCE IS BEHIND THE FIRST TROUGH EXCEPT IN
THE VICINITY OF SECOND DISTURBANCE NOTED ABOVE.

Watching for Subtropical Development

Watching for Subtropical Development

San Juan nws office mentions the low

Check out the UKMET - it closes the low off and actually ..

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