[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 150540
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI 15 APR 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS
OF SOUTH AMERICA...AND 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0345 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 9N10W 4N19W 5N28W 3N42W 2N52W.
NUMEROUS STRONG CONVECTION IS WITHIN 60/75 NM OF THE AXIS FROM
14W-18W. SIMILAR CONVECTION IS APPROACHING THE PRIME MERIDIAN.
SCATTERED/NUMEROUS STRONG CONVECTION IS WITHIN 90 NM N OF THE
AXIS FROM 18W-22W AND WITHIN 30 NM OF 4N FROM 7W-10W. SCATTERED
MODERATE/STRONG CONVECTION IS WITHIN 60 NM OF 2.5N FROM 14W-18W.
CLUSTERS OF SIMILAR CONVECTION ARE FROM 1N TO THE COAST OF SW
AFRICA E OF 14W TO ACROSS THE PRIME MERIDIAN. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE S OF THE ITCZ
AXIS W OF 30W TO INLAND OVER SOUTH AMERICA.

...DISCUSSION...

GULF OF MEXICO INTO THE W ATLANTIC...
SURFACE RIDGE OF HIGH PRESSURE CONTINUES TO BUILD SLOWLY DOWN
THE E SLOPES OF THE SIERRA MADRES AND INTO THE W GULF WITH THE
MID/UPPER LEVEL RIDGING ALONG 98W. PACIFIC MOISTURE IS BEING
ADVECTED ACROSS N MEXICO AND TEXAS TO OVER THE W GULF W OF 90W.
A COMPLEX AREA OF LOW PRESSURE/GALE CENTER CONTINUES TO BUILD
OVER THE W ATLC. THIS SYSTEM IS LINKED TO A CUT-OFF UPPER LOW
CENTERED E OF SOUTH CAROLINA WITH BROAD TROUGHING REACHING DOWN
INTO THE NW CARIBBEAN...WITH NW WINDS FLOWING FROM MEXICO ACROSS
THE GULF AREA. THE COLD FRONT NOW EXTENDS THROUGH 32N67W SW
ACROSS THE CENTRAL BAHAMAS NEAR 23N75W OVER CENTRAL CUBA INTO
THE CARIBBEAN. NUMEROUS SHOWERS/THUNDERSTORMS ARE WITHIN 180 NM
E OF THE FRONT N OF 25N DUE TO FAVORABLE UPPER LEVEL DIFFLUENCE
AND BEING NEAR THE LEFT EXIT REGION OF AN UPPER JET WITH
SCATTERED SHOWERS WITHIN 180 NM OF EITHER SIDE OF THE FRONT.
MID-LEVEL INSTABILITY ASSOCIATED WITH THE CUT-OFF LOW IS ALSO
PRODUCING A BAND OF LOW CLOUDS OVER THE W ATLC N OF A SURFACE
TROUGH THAT EXTENDS FROM THE 1000 MB GALE CENTER NEAR 32N75W TO
THE FLORIDA COAST NEAR 27N80W. N/NE SURFACE FLOW DOMINATES THE
GULF BEHIND THE FRONT WITH COLD AIR STRATOCUMULUS CLOUDS N OF
22N E OF 91W. THIS SURFACE FLOW WILL TURN EASTERLY OVER THE NEXT
24 HOURS AS THE COLD FRONT MOVES INTO THE CENTRAL ATLC.

CARIBBEAN...
MID/UPPER LEVEL TROUGH OVER THE GULF AND W ATLC DIPS INTO THE NW
CARIBBEAN N OF 20N W OF 76W WITH THE ASSOCIATED COLD FRONT
ENTERING THE CARIBBEAN ACROSS CENTRAL CUBA NEAR 22N78W EXTENDING
SSW ALONG 18N86W INTO THE GULF OF HONDURAS TO THE COAST OF
HONDURAS NEAR 15N88W. SCATTERED SHOWERS/THUNDERSTORMS ARE S OF
19N W OF THE FRONT TO INLAND OVER BELIZE WITH SCATTERED SHOWERS
WITHIN 180 NM E OF THE FRONT N OF 18N. WESTERLY UPPER FLOW
DOMINATES THE AREA SPREADING A DEEPER DRY AIR MASS OVER THE AREA
SE OF THE FRONT. THE ILL-DEFINED SOUTH AMERICAN UPPER HIGH
REMAINS...ALTHOUGH THE ANTICYCLONIC FLOW IS WEAKER AND STILL
CIRCULATING ACROSS THE LESSER ANTILLES. THE COLD FRONT WILL
CONTINUE SLIDE E OVER THE NEXT COUPLE OF DAYS...ALTHOUGH IT WILL
BEGIN TO WEAKEN DURING THE DAY FRIDAY...SHOWERS WILL CONTINUE
ACROSS THE REMAINDER OF THE GREATER ANTILLES.

ATLANTIC...
DEEP-LAYERED TROUGH CONTINUES TO SPREAD E ACROSS THE W ATLC AS
THE CUT-OFF UPPER LOW OFF THE SOUTH CAROLINA COAST PUSHES THE
ASSOCIATED COLD FRONT E OF BERMUDA DURING THE DAY THU. THE
REMAINDER OF THE ATLC BASIN IS DOMINATED BY BROAD...STRONG
SURFACE HIGH PRESSURE WITH THE MAIN RIDGE ALONG 32N40W TO NEAR
THE LEEWARD ISLANDS. THE UPPER FLOW IS DOMINATED BY TROUGH OVER
THE CENTRAL ATLC WITH A WEAKENING UPPER CUT-OFF LOW CENTERED
NEAR 23N38W. THE STRONGEST UPPER LEVEL WESTERLY FLOW HAS BEEN
SUPPRESSED TO S OF 13N EXTENDING TO THE EQUATOR ALTHOUGH ITCZ
CONVECTION HAS BECOME VERY ACTIVE ESPECIALLY E OF 20W WHERE THE
VERTICAL SHEAR IS NOT QUITE AS STRONG.

$$
WALLACE


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