[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 212307
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST TUE MAR 21 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
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...WEATHER OBSERVATIONS...
RADAR...AND METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2300 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 6N10W 3N20W 1N30W EQ40W 1S49W.
CLUSTERS OF WEAKENING MODERATE CONVECTION IS MOSTLY WITHIN 175
NM TO THE NORTH OF THE AXIS BETWEEN 22W-28W AND 38W-44W. A SMALL
PATCH OF MODERATE CONVECTION HAS RECENTLY FIRED FROM 1N-3N
BETWEEN 11W-13W. ELSEWHERE...SCATTERED SHOWERS AND ISOLATED
EMBEDDED TSTMS SURROUND THE AXIS.

...DISCUSSION...

GULF OF MEXICO...
A BROAD MID-UPPER RIDGE COVERS THE EASTERN GULF AND W ATLANTIC
WITH THE UPPER AXIS ALONG 79W/80W. THIS RIDGE HAS BECOME
CONSIDERABLY LESS AMPLIFIED THAN IT WAS OVER THE PAST FEW DAYS.
A WEAKENED SUB-TROPICAL JET EXTENDS FROM THE EPAC ACROSS MEXICO
TO NORTH FLORIDA. THE JET IS ADVECTING CONSIDERABLE MOISTURE
INTO THE GULF OF MEXICO NW OF A LINE FROM 20N97W 26N89W 27N82W.
SE OF THIS LINE...MODERATE SUBSIDENCE DOMINATES. AT THE
SURFACE...A COLD FRONT EXTENDS FROM NORTH FLORIDA TO S MEXICO
ALONG 31N81W 25N90W 20N96W...THEN BECOME STATIONARY ALONG THE E
SLOPES OF THE SIERRA MADRE MOUNTAINS TO 25N100W. SCATTERED
MULTILAYER CLOUDS AND ISOLATED SHOWERS EXTEND WITHIN 150 NM OF
THE BOUNDARY. THICK LOW CLOUDS ARE BANKED UP AGAINST THE
SOUTHERN PORTION OF THE SIERRA MADRE MOUNTAINS. TAMPA BAY RADAR
IMAGERY INDICATES A VERY NARROW LINE OF SHOWERS AND WEAKENING
THUNDERSTORMS FROM 27N93W TO CAPE CANAVERAL. SURFACE WINDS ARE
SWLY FROM 10-15 KT AHEAD OF THE FRONT WITH STRONGER N/NW WINDS
BEHIND THE BOUNDARY. THE COLD FRONT WILL CONTINUE SEWARD AND
BECOME MORE HORIZONTAL ORIENTED TO A POSITION FROM THE STRAITS
OF FLORIDA TO THE BAY OF CAMPECHE WEDNESDAY AFTERNOON
ACCOMPANIED BY AN INCREASE IN THE CHANCE OF SHOWERS. A STRONGER
COLD FRONT WILL FORM AND CROSS THE ENTIRE AREA ON FRIDAY
BRINGING A NOTICEABLE COOLER AND DRIER AIRMASS. GALE CONDITIONS
ARE EXPECTED WITH THE PASSAGE OF THIS FRONT.

CARIBBEAN...
A MID-UPPER LEVEL HIGH IS CENTERED NEAR 9N55W WITH ITS ENVELOPE
OF ANTICYCLONIC FLOW DOMINATING THE CARIBBEAN E OF 75W.
CONSIDERABLE MID-UPPER LEVEL MOISTURE FORMING OVER S AMERICA IS
FLOWING AROUND THE UPPER HIGH AND BREAKING UP AS IT TRAVELS
EASTWARD. ANOTHER MID-UPPER HIGH IS LOCATED IN THE EPAC NEAR
8N95W PRODUCING ANTICYCLONIC FLOW OVER CENTRAL AMERICA. STRONG
SUBSIDENCE DOMINATES THE CARIBBEAN W OF 75W. AT THE
SURFACE...PATCHES OF LOW CLOUDS ARE DRIVEN WESTWARD BY MODERATE
EASTERLY TRADES. THE SURFACE FLOW BECOME SELY W OF 80W. A FEW
SHOWERS ARE OVER THE VIRGIN ISLANDS...PUERTO RICO AND HISPANIOLA
ASSOCIATED WITH A SFC TROUGH TO THE NE OF THE AREA AND ENHANCED
BY THE LOCAL OROGRAPHY. MODERATE TRADES ARE EXPECTED TO CONTINUE
THROUGH TOMORROW AS THE ATLANTIC SURFACE RIDGE REMAINS IN PLACE.

ATLANTIC...
A RATHER ZONAL RIDGE/TROUGH/RIDGE PATTERN COVERS THE ATLANTIC. A
A MID TO UPPER RIDGE IS OVER THE GULF OF MEXICO AND W ATLANTIC W
OF 60W. AT THE SURFACE...A 1020 MB HIGH IS LOCATED NEAR 27N62W.
MAINLY FAIR WEATHER EXISTS UNDER THE INFLUENCE OF THE RIDGE.
A DEEP LAYER TROUGH COVERS THE CENTRAL ATLANTIC BETWEEN 35W-60W.
AT THE SURFACE...A COMPLEX SERIES OF CYCLONES AND FRONTAL
BOUNDARIES HAVE DEVELOPED IN THIS AREA...MOST OF THEM ARE TO THE
NORTH OF 32N...HOWEVER TWO COLD FRONTS ARE IN THE DISCUSSION
AREA. THE WESTERN-MOST FRONT IS DRAPED FROM A 988 MB LOW NEAR
40N45W TO 30N51W. LOW-MID LEVEL CLOUDS ARE WITHIN 75 NM AHEAD OF
THIS BOUNDARY WITH WIDESPREAD STRATOCUMULUS CLOUDS BUILDING IN
BEHIND THE FRONT. ANOTHER COLD FRONT IS LOCATED ABOUT 150-200 NM
SE OF THIS FRONT ALONG 32N40W 25N53W 22N64W. A BROKEN LINE OF
MULTILAYER CLOUDS AND ISOLATED SHOWERS STRETCH 100 NM AHEAD OF
THIS FRONT. A PRE-FRONTAL TROUGH LIES 150-200 NM E OF THIS FRONT
ALONG 31N37W 24N50W 19N61W. A SIMILAR LINE OF BROKEN CLOUDS AND
ISOLATED SHOWERS ARE ASSOCIATED WITH THIS SURFACE TROUGH. A
BROAD SOMEWHAT AMPLIFIED MID-UPPER RIDGE COVERS THE REMAINDER OF
THE ATLANTIC E OF 35W. STRONG SUBSIDENCE IS EVIDENT ON WATER
VAPOR IMAGERY FROM 15N-25N E OF 40W. AT THE SURFACE...A 1020 MB
HIGH IS LOCATED NEAR 29N22W PRODUCING MAINLY FAIR WEATHER THE
EAST ATLANTIC.

$$
CANGIALOSI







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