[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 082341
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN MAR 08 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.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 5N10W 1N20W CROSSING THE EQUATOR
NEAR 22W EXTENDING TO 1S40W AND INTO NE BRAZIL NEAR 2S45W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NEAR 4N8W.
ISOLATED MODERATE CONVECTION IS S OF 2N BETWEEN 8W-13W. SIMILAR
CONVECTION IS NOTED ALONG THE EQUATOR BETWEEN 14W-20W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL RIDGE WITH AXIS FROM THE BAY OF CAMPECHE TO THE
FLORIDA PANHANDLE DOMINATES MUCH OF THE GULF AND SE CONUS. THIS
UPPER-LEVEL FEATURE IS PRODUCING MODERATE TO STRONG SUBSIDENCE
SE OF A LINE FROM NEW ORLEANS LOUISIANA TO JUST SOUTH OF
BROWNSVILLE TEXAS. STRONG SWLY UPPER-LEVEL WINDS ARE ADVECTING
MID/UPPER LEVEL MOISTURE FROM THE EPAC REGION INTO NORTHERN
MEXICO AND THE NORTH GULF STATES INCLUDING ALSO THE NW CORNER OF
THE GULF. SOUTHEASTERLY SURFACE RETURN FLOW OF 15-20 KT RESIDES
ON THE WRN PERIPHERY OF A SURFACE RIDGE THAT EXTENDS FROM A 1028
MB HIGH IN THE W ATLC NEAR 28N72W. FRESH E-SE WINDS CONTINUE TO
FILTER THROUGH THE STRAITS OF FLORIDA AND INTO THE FAR SE GULF.
THESE WINDS ARE TRANSPORTING PATCHES OF LOW-LEVEL CLOUDS WITH
POSSIBLE ISOLATED SHOWERS. THE SURFACE HIGH IS FORECAST TO
REMAIN NEARLY STATIONARY WHILE GRADUALLY WEAKENING. AS A
RESULT...THE OVERALL WEATHER PATTERN ACROSS THE GULF WILL CHANGE
LITTLE THROUGH MID-WEEK. LOOKING AHEAD...THE NEXT COLD FRONT IS
EXPECTED TO MOVE INTO THE EXTREME NW GULF LATE EARLY THU MORNING
THEN STALL THROUGH FRI.

CARIBBEAN SEA...
FRESH TO STRONG WINDS ASSOCIATED WITH A 1028 MB SURFACE HIGH
CENTERED IN THE W ATLC NEAR 28N72W ARE ADVECTING POCKETS OF
SHALLOW MOISTURE WITH EMBEDDED ISOLATED LIGHT SHOWERS ACROSS THE
GREATER ANTILLES AND MUCH OF THE CARIBBEAN SEA. AN EARLIER ASCAT
PASS SHOWED E-NE WINDS OF 20-30 KT OVER MUCH OF THE CENTRAL
CARIBBEAN. THE STRONGEST WINDS OF 30-35 KT ARE OCCURRING OFF THE
COAST OF COLOMBIA WHERE A GALE WARNING REMAINS IN EFFECT. THESE
STRONG WINDS ARE THE RESULT OF A TIGHT SURFACE PRESSURE GRADIENT
BETWEEN THE AFOREMENTIONED HIGH OVER THE W ATLC AND LOWER
PRESSURE OVER NRN SOUTH AMERICA. ALOFT...STRONG SUBSIDENCE IS
RESULTING FROM CONFLUENCE IN WESTERLY UPPER LEVEL FLOW...
MAXIMIZED OVER THE ERN CARIBBEAN...AND IT IS THIS UPPER LEVEL
REGIME THAT CONTINUES TO LIMIT ANY DEEP CONVECTION ACROSS THE
BASIN.

ATLANTIC OCEAN...
A DEEP LAYERED LOW PRES SYSTEM PERSISTS OVER THE CENTRAL ATLC
WITH A 1004 MB OCCLUDED SURFACE LOW CENTERED NEAR 26N51W. THE
ATTENDANT COLD FRONT EXTENDS FROM 29N46W ALONG 20N44W SW TO
10N52W. SCATTERED SHOWERS ARE WITHIN 90 NM OF THE COLD FRONT
WHILE UPPER LEVEL DIFFLUENCE TO THE NE OF THE LOW IS AIDING IN
GENERATING SCATTERED MODERATE CONVECTION WITHIN 300 NM NE OF THE
FRONT N OF 24N. THIS LOW PRES SYSTEM IS PRODUCING GALE FORCE
WINDS PARTICULARLY TO THE W AND N SEMICIRCLES OF THE LOW CENTER.
SEE THE HIGH SEAS FORECAST FOR DETAILS. ACROSS THE W ATLC...A
RELATIVELY COOLER AND DRIER AIRMASS REMAINS IN PLACE COURTESY OF
A 1028 MB SURFACE HIGH CENTERED NEAR 28N72W. BROKEN COLD AIR
STRATOCUMULUS CLOUDS ARE STILL NOTED ON SATELLITE IMAGERY ACROSS
THE W ATLC INTO THE BAHAMAS AND CUBA UNDER THE PREVAILING E-NE
WIND FLOW. FARTHER TO THE EAST...AN UPPER-LEVEL LOW CONTINUES TO
SPIN OVER THE E ATLC JUST NORTH OF THE CANARY ISLANDS. A WEAK
1013 MB SURFACE LOW IS CENTERED NEAR 30N15N WITH A SURFACE
TROUGH ANALYZED FROM THE LOW ALONG 26N12W 21N13W TO 18N13W.
ATMOSPHERIC INSTABILITY ASSOCIATED WITH THIS FEATURE IS
SUPPORTING AN AREA OF SCATTERED SHOWERS OVER SRN MOROCCO. ACROSS
THE TROPICAL ATLC...A BROAD UPPER-LEVEL RIDGE CENTERED NEAR
6N17W IS ENHANCING CONVECTION ALONG THE ITCZ AXIS...NE BRAZIL
AND THE GUYANAS.

$$
GR






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