[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 272323
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED MAY 27 2009

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

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

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 79W FROM 05N TO 16N AND HAS BEEN MOVING
W AT 17 KT THE PAST 24 HOURS. CURRENTLY THERE IS SOME CYCLONIC
ROTATION ALONG THE WAVE AXIS OVER THE PACIFIC WATERS. THE WAVE
WAS PREVIOUSLY UNDER THE W PERIPHERY OF AN UPPER RIDGE THAT
ENHANCED CONVECTION ALONG THE PACIFIC COAST OF COLOMBIA.
THE WAVE HAS MOVED W OF THESE FAVORABLE CONDITIONS AND
CONVECTION HAS DECREASED CONSIDERABLY LATE THIS AFTERNOON.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 05N09W TO 06N14W CROSSING THE
EQUATOR AT 38W TO THE SOUTH AMERICAN COAST AT 02S46W. SCATTERED
MODERATE AND ISOLATED STRONG CONVECTION IS NOTED FROM 01S TO 07N
BETWEEN 03W AND 32W.

...DISCUSSION...

GULF OF MEXICO...
ALOFT...A SHORTWAVE RIDGE ORIGINATING OVER THE TROPICAL E
PACIFIC IS CRESTING OVER THE GULF OF MEXICO ALONG POINTS 28N96W
26N96W 22N82W. CONVECTION IS ENHANCED ALONG THE RIDGE CREST...
ROUGHLY WITHIN 90 NM OF 27N86W...AND MOVING E AND DIMINISHING
WITH TIME. AN UPPER SHORTWAVE TROUGH IS SWINGING E ACROSS
CENTRAL TEXAS WITH AN ASSOCIATED COLD FRONT APPROACHING THE
TEXAS COAST. A PREFRONTAL TROUGH IGNITED A LARGE CLUSTER OF
CONVECTION ALONG THE E CENTRAL TEXAS COAST WITH AN OUTFLOW
BOUNDARY RACING SE ACROSS THE NW GULF WATERS DEFINED BY A LINE
OF TOWERING CUMULUS. THE REMAINDER OF THE UPPER LEVELS APPEAR
QUITE DRY. AGRICULTURE SMOKE IS NOTED OVER THE EASTERN BAY OF
CAMPECHE AND SPREADING N TO ALONG 24N BETWEEN 94W AND 87W.

CARIBBEAN SEA...
AN UPPER RIDGE DOMINATES THE WESTERN CARIBBEAN WHILE AN UPPER
TROUGH IS SWINGING E THROUGH THE AREA BETWEEN 75W AND 70W.
CONVECTION IS ENHANCED ALONG THE E COAST OF CENTRAL AMERICA FROM
HONDURAS TO COSTA RICA...WITH THE DEBRIS MOISTURE SPREADING E
OVER THE AREA TO THE S OF 15N AND W OF 76W. SOME UPPER
MOISTURE...ORIGINATING FROM A CLUSTER OF CONVECTION THAT FLARED
JUST S OF JAMAICA...IS STREAMING E ALONG 17N TO NEAR 70W WHERE
IT MERGES WITH DEBRIS MOISTURE FROM CONVECTION OVER INTERIOR
HISPANIOLA. THE COMBINED MOISTURE PLUME CONTINUES E ACROSS THE
CARIBBEAN TO N OF 15N E OF 65W. THE UPPER LEVELS ARE DRY S OF
15N E OF 75W. ATLC HIGH PRESSURE IS MAINTAINING FRESH E TRADES
ACROSS THE LOW LEVELS WITH SHOWERS ENHANCED OVER THE SW
CARIBBEAN.

ATLANTIC OCEAN...
AN UPPER ANTICYCLONE IS CENTERED NEAR 27N64W WITH A RIDGE
EXTENDING N TO WELL BEYOND 32N67W. IMMEDIATELY TO THE W OF THIS
RIDGE IS A SMALL UPPER CYCLONE OVER SE GEORGIA AT 31N81W...WITH
A TROUGH EXTENDING S AND SE ALONG THE E COAST OF FLORIDA AND
ACROSS THE SE BAHAMAS TO 21N72W. AFTERNOON SEABREEZE CONVECTION
IS ENHANCED WITHIN 120 NM OF THIS TROUGH...WITH THE OVERALL AREA
OF CONVECTION SHIFTING E ACROSS THE BAHAMAS AND OVER THE SW ATLC
TO THE S OF 27N W OF 68W. DEBRIS MOISTURE FROM THIS CONVECTION
IS ADVECTED N UNDER THE UPPER RIDGE WELL TO THE N OF 32N...BUT
SOME OF THE MOISTURE IS NOW SPILLING SE ACROSS TE RIDGE BACK
INTO THE AREA TO THE N OF 27N BETWEEN 58W AND 68W. A TROPICAL
UPPER ANTICYCLONE IS AT 05N16W WITH A RIDGE EXTENDING NW AND
CRESTING ALONG POINTS 14N45W TO 26N29W TO 31N19W. DEBRIS
MOISTURE IS NOTED ALONG THE PERIPHERY OF THIS RIDGE. AN UPPER
TROUGH DOMINATES THE CENTRAL ATLC BETWEEN THESE LARGE
ANTICYCLONES...ROUGHLY ALONG 32N42W TO 20N48W. A FEW CONVECTIVE
CLUSTERS ARE ENHANCED ALONG THIS TROUGH...BUT THE MOST PART VERY
DRY AIR IS INDICATED TO THE N OF 18N BETWEEN 58W AND 40W. AN
ASSOCIATED SURFACE COLD FRONT IS APPROACHING THE AREA FROM
32N44W TO TO 30N54W ACCOMPANIED BY OVERCAST MULTILAYERED CLOUDS
WITHIN 120 NM NW AND N OF THE LEADING EDGE.

$$
NELSON





This weather bulletin was brought to you by:
www.nashvilleweather.net