[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 071752
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST FRI MAR 07 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N10W 1N20W 1N30W THEN ALONG THE
EQUATOR BETWEEN 25W-35W TO 3S46W. CLUSTERS OF MODERATE TO STRONG
CONVECTION ARE FROM 1N TO THE SW COAST OF AFRICA BETWEEN THE
PRIME MERIDIAN AND 10W. SIMILAR CONVECTION IS SEEN WITHIN 120 NM
EITHER SIDE OF AXIS EAST OF 15W. SCATTERED MODERATE CONVECTION
IS FROM FROM EQ-6N BETWEEN 42W-50W.

...DISCUSSION...

THE GULF OF MEXICO...

A STRONG COLD FRONT IS MOVING ACROSS THE GULF FOLLOWED BY GALE
FORCE WINDS. A DEEP LAYERED TROUGH OVER THE CENTRAL CONUS AND NE
MEXICO SUPPORTS THE FRONT. AS OF 1500 UTC...THE COLD FRONT
EXTENDS FROM A 1004 MB LOW LOCATED OVER SOUTHERN ALABAMA TO NEAR
VERACRUZ MEXICO. THE CITY OF VERACRUZ IS NOW REPORTING SUSTAINED
WINDS OF 40 KT WITH GUSTS UP TO 50 KT. A GALE WARNING IS IN
EFFECT BEHIND THE FRONT...BUT WINDS ARE EXPECTED TO GRADUALLY
DIMINISH TONIGHT. THE FRONTAL SYSTEM WILL EXTEND FROM THE
FLORIDA BIG BEND TO THE EASTERN YUCATAN PENINSULA THIS EVENING
AND SHOULD SWEEP THROUGH THE REMAINDER OF THE GULF BY SAT
MORNING. THE COMBINATION OF LOW-LEVEL CONVERGENCE AND A
DIFFLUENT PATTERN ALOFT IS PRODUCING ACTIVE WEATHER AHEAD OF THE
FRONT. SATELLITE IMAGERY AND DOPPLER RADAR SHOW A BAND OF STRONG
SHOWERS AND TSTMS EXTENDING FROM 24N90W THROUGH THE FLORIDA BIG
BEND TO SE GEORGIA. A SQUALL LINE IS ANALYZED IN THIS AREA. COLD
AIR STRATOCUMULUS CLOUDS ARE FOUND OVER THE NW PORTION OF THE
GULF. AN EARLY MORNING QUIKSCAT PASS AND SFC WIND OBSERVATIONS
INDICATE THAT S TO SW WINDS OF 20-25 KT ARE BLOWING AHEAD OF THE
FRONT OVER THE EASTERN GULF...THE FLORIDA KEYS AND SOUTH FLORIDA.

THE CARIBBEAN SEA...

LARGE MID TO UPPER HIGH DOMINATES THE REGION EXCEPT FOR THE
FAR E PORTION WHERE UPPER TROUGHING IS INDUCED BY A LARGE CUT
OFF LOW CURRENTLY LOCATED IN THE EASTERN ATLANTIC NEAR 28N38W AT
500 MB. WIDESPREAD SUBSIDENCE IS ASSOCIATED WITH THESE UPPER
SYSTEMS. THIS FAIRLY STABLE ENVIRONMENT ALOFT IS CAPPING THE
TYPICAL LOW-LEVEL CLOUD PATCHES...WHICH ARE MOST ORGANIZED IN
BANDS OVER THE EASTERN CARIBBEAN JUST SOUTH OF PUERTO RICO. THE
SAN JUAN DOPPLER RADAR SHOWS SCATTERED SHOWERS AND ISOLATED
TSTMS ON THE CARIBBEAN SIDE. HIGH PRES OVER CENTRAL ATLC
MAINTAINS MODERATE TO FRESH TRADE WINDS ACROSS MOST OF BASIN.
THESE WINDS WILL PERSIST DURING THE UPCOMING WEEKEND. THE COLD
FRONT THAT IS NOW MOVING ACROSS THE GULF OF MEXICO WILL REACH
THE NW CARIBBEAN EARLY SAT WITH FRESH NLY FLOW AND BUILDING SEAS
BEHIND IT.

THE ATLANTIC OCEAN....

THE MAIN WEATHER FEATURE ACROSS THE FORECAST AREA IS A 1005 MB
LOW SPINNING NEAR 28N37W. THIS LOW REMAINS QUASI-STATIONARY. THE
AIR MASS AROUND THIS LOW HAS BECOME MORE HOMOGENEOUS DURING THE
LAST 24 HOURS...AND THERE ARE NO FRONTS ASSOCIATED WITH THIS
CYCLONE ANY LONGER. INSTEAD...A SFC TROUGH IS ANALYZED FROM THE
SFC LOW TO 20N41W. SCATTERED SHOWERS AND TSTMS ARE MOST
ORGANIZED IN BANDS N AND NE OF THE LOW. TIGHT PRES GRADIENT
BETWEEN THIS CYCLONE AND HIGH PRES OVER THE CENTRAL ATLC IS
PRODUCING A LARGE AREA OF MODERATE TO STRONG NE WINDS IN THE NW
SEMICIRCLE OF THE LOW. ACCORDING TO THE GFS COMPUTER MODEL...THE
LOW WILL SLOWLY DRIFT SW AND WEAKEN DURING THIS WEEKEND. MOST OF
THE WEST AND CENTRAL ATLC ARE UNDER THE INFLUENCE OF A RIDGE
ANCHORED ON A 1031 MB HIGH LOCATED NEAR 36N52W. FRAGMENTS OF LOW
LEVEL CLOUDS ARE OBSERVED ACROSS THE AREA WITH SLY RETURN FLOW
ACROSS THE BAHAMAS AND THE WESTERN ATLC WEST 0F 70W. ALOFT...A
RIDGE/TROUGH/RIDGE PATTERN DOMINATES THE AREA. A JET STREAM
BRANCH WITH CORE WINDS OF 90-130 KT LIES BETWEEN THE PREVIOUSLY
MENTIONED LARGE CUT-OFF LOW OVER THE EASTERN ATLC AND A BROAD
UPPER-LEVEL HIGH LOCATED SE OF THE CAPE VERDE ISLANDS NEAR
9N18W. UPPER SLY FLOW ON THE WESTERN SIDE OF THE HIGH IS
ADVECTING PATCHY HIGH LEVEL CLOUDS FROM N SOUTH AMERICA ACROSS
THE TROPICAL ATLC. THESE WINDS ARE ALSO ENHANCING SCATTERED
MODERATE CONVECTION N OF THE ITCZ AXIS AND WEST OF 40W.

$$
GR

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