Memorial Day Weekend Area to Watch

IMHO things are about to get very interesting for Florida. I touched upon it in my afternoon AFD, but I have a little time to expand on these thoughts, so here goes.

First thing to mention is that the pressures are usually fairly low in the western Caribbean, and today is no exception. I noticed some buoy/ship ops around 1010MB in that general area. Second, there are two well defined vortices in the CU field noticeable on vis imagery. The first is east of the Yucatan (18N 87W) and the second is east of Nicaragua (12.5n 80W). The one east of Nicaragua looks a little tigher and has more in the way of convection near the center, plus a huge slug of deep tropical moisture/convection to it's east.

(better to view the link below if you have broadband and a large monitor, or simply change the height/width to 600/600)

http://wwwghcc.msfc.nasa.gov/cgi-bin/get...p;mapcolor=gray

What gets really interesting is the change in the synoptic pattern over the GOMEX over the next several days. If you'll allow me to cannibalize my own AFD...

XTD...AS HAS OFTEN BEEN THE CASE IN THE PAST...THE 12Z GFS HAS TRENDED DECIDEDLY TOWARD THE LAST SEVERAL RUNS OF THE ECM AT H50...W/R/T BOTH THE MORE PROGRESSIVE NRN STREAM...AND MORE IMPORTANTLY...H50 HEIGHT FALLS MOVING INTO THE GOMEX FROM MID WEEK ONWARD...WHICH MAY BE A HARBINGER OF SOME FAIRLY DECENT CHCS FOR SOME MUCH NEEDED RAINFALL FROM DIURNAL CONVECTION BY LATE NEXT WEEK.

and...

MED RANGE MODEL GUIDANCE SUGGESTS AN INCREASING CHANCE FOR A MUCH NEEDED WIDESPREAD/HIGH COVERAGE RAIN EVENT LATE NEXT WEEK AS WE HEAD INTO JUNE. CONTINUED AMPLIFICATION OF THE WEAK SRN STREAM TROUGH IS PROGGED TO OCCUR OVER THE GOMEX BY BOTH THE 00Z ECM AND 12Z GFS. ECM IS MUCH MORE ROBUST WITH BOTH THE H50 TROUGH...AND THE SURFACE RESPONSE...HOWEVER BOTH SOLNS SHOW ENOUGH AMPLITUDE TO ALLOW DEEP LYR FLOW TO ACQUIRE SIGNIF SRLY COMPONENT TO ADVECT DEEP TROPICAL MOISTURE NWD INTO FL. BY FRI/SAT...THE ECM SHOWS A MORE CUTOFF/SLOWER SOLN...WHILE THE GFS LINKS THIS WEAKNESS UP WITH THE NRN STREAM...CREATING A BROADER MORE FULL LATITUDE TROUGH. IT`S HARD TO IGNORE THAT THE GFS HAS OFTEN FOLLOWED THE ECM`S LEAD WITH THE CURRENT PATTERN...AND IT IS ENCOURAGING TO SEE BETTER AGREEMENT BTWN THE TWO...THOUGH IT STILL IS IN THE DAY 4+ TIME FRAME. SO CAN`T
BITE OFF ON THESE SOLNS UNTIL CONTINUITY IS BETTER ESTABLISHED. FOR NOW HAVE GONE JUST A LITTLE MORE BULLISH FOR POPS THU...AND KEPT SCT SHRA/TSRA IN THE FCST FOR FRI/SAT.

Adding onto that is the fact that the 12Z ECM continued to be much stronger at H50 and with the surface low coming up out of the Caribbean.

So, we have
(1) low pressure in the area
(2) a fairly healthy low level vortex already down there sitting and spinning
(3) a loose model consensus for "something" to form from the ECM/UKM and GFS (in spite of the return of it's horrible convective feedback problem and resultant low spin-up-o-rama)

This is where it gets interesting. Significant height falls at 500 MB will occur over the western GOMEX and gulf coast starting TUE, and responsible trough will work eastward toward Florida from mid to late next week.

Going back to my AFD, The ECM is deeper, so much that it looks like it's weakly cutoff at 500MB. The surface evolution looks a little strange in that the 500MB low actually captures the surface system coming out of the Caribbean. We wind up with a 1001MB low getting propelled northward into the FL panhandle.

On the other hand, the GFS takes the distinct southern stream 500MB feature eastward, but it gets captured and absorbed into the base of the northern stream trough, making it nearly full latitude. It's surface low, which looks like it's from convective feedback, forms farther east and turns more quicky across extreme SE Florida and then out to sea.

I have no strong opinion on which model to favor at this point, other than noting as I did in my AFD that the GFS has been following the ECM's lead up until now. I think there will be quite a bit of interest for Florida folks over the next several days.

Tony C.

edit: On more note - It's still only may and the ST Jet will stay pretty strong between 25 and 30N. That would argue for something not purely tropical, or a system morphing into a "sloppy, right-sided, hybrid, baroclincally enhanced thingamajiggy" (for lack of a better term)

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