[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 170519
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST THU 17 MAR 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 7N10W 3N18W 1N25W 2N40W 1N50W.
SCATTERED MODERATE WITH EMBEDDED AREAS OF SCATTERED/NUMEROUS
STRONG CONVECTION ARE WITHIN 180 NM OF THE AXIS FROM THE COAST
OF AFRICA TO 19W AND FROM 30W-46W.

...DISCUSSION...

GULF OF MEXICO...
COMPLEX PATTERN CONTINUES OVER THE GULF AS YET ANOTHER S STREAM
SHORTWAVE TROUGH MOVES ACROSS MEXICO INTO S TEXAS. A
STRENGTHENING UPPER JET IN EXCESS OF 130 KT EXTENDS AROUND THE E
SIDE OF THE TROUGH FROM NE MEXICO NE OVER THE E UNITED STATES.
THIS JET WILL BE SHIFTING E ACROSS THE GULF OVER THE NEXT 24
HOURS. DYNAMICS/LIFT NEAR THE CURRENT ENTRANCE REGION OF THE JET
IS PRODUCING AN AREA OF NUMEROUS SHOWERS/THUNDERSTORMS TO OVER
THE NE GULF AND FLORIDA PENINSULA. AT THE SURFACE...COLD FRONT
EXTENDS FROM A 1004 MB LOW OFF THE COAST OF SOUTH CAROLINA TO A
WEAKENING 1006 MB LOW OVER NE FLORIDA INTO THE GULF ALONG 29N86W
24N91W TO OVER S MEXICO NEAR 18N95W THEN AS A STATIONARY FRONT
NW AGAINST THE E SLOPES OF THE SIERRA MADRE MOUNTAINS. AREA OF
LOW PRESSURE IS EXPECTED TO MOVE E AND STRENGTHEN SWEEPING THE
COLD FRONT ACROSS THE REMAINDER OF THE GULF AND FLORIDA DURING
THE NEXT 24 HOURS. THE STRONGEST SHOWERS/THUNDERSTORMS ARE
WITHIN 75/90 NM OF LINE FROM OVER THE NE YUCATAN PENINSULA TO NE
FLORIDA. THE FRONT IS THEN EXPECTED TO CLEAR S FLORIDA BY THU
NIGHT WITH POST-FRONTAL N FLOW ACROSS THE ENTIRE AREA BY FRI.

CARIBBEAN...
THE PATTERN REMAINS HIGH AND DRY OVER THE CARIBBEAN AS STRONG
MID/UPPER LEVEL RIDGING CONTINUES TO DOMINATE THE ENTIRE AREA.
AN UPPER HIGH THAT REMAINS OFF THE N COAST OF VENEZUELA NEAR THE
ABC ISLANDS WITH BROAD ANTICYCLONIC FLOW COVERING THE GULF OF
MEXICO...CARIBBEAN...AND THE W ATLC W OF 55W. MODERATE/STRONG
SUBSIDENCE IS PRODUCING VERY DRY/STABLE CONDITIONS ALOFT. LOW
LEVEL MOISTURE IS ALSO LIMITED WITH MINIMAL SHOWER ACTIVITY
ACROSS THE AREA. CONDITIONS ARE EXPECTED TO REMAIN DRY OVER MOST
OF THE AREA EXCEPT IN THE NW WHERE THE APPROACHING COLD FRONT
FROM THE GULF WILL PROVIDE INCREASING CLOUDINESS WITH
SHOWERS/THUNDERSTORMS MOVING INTO THE YUCATAN CHANNEL. THIS
ACTIVITY WILL CONTINUE TO SPREAD E ACROSS CUBA LATER THIS
MORNING AS THE FRONT CLEARS THE GULF OF MEXICO.

ATLANTIC...
LARGE AMPLITUDE RIDGE-TROUGH-RIDGE PATTERN PREVAILS OVER THE
SUBTROPICAL ATLANTIC WITH A BROAD MID/UPPER LEVEL RIDGE W OF
55W...DEEP LAYERED TROUGH OVER THE CENTRAL ATLC BETWEEN
28W-55W...AND RIDGE OVER THE E ATLC E OF 28W INTO NW AFRICA. THE
BULK OF THE ACTIVE WEATHER IS FOCUSED ALONG AND AHEAD OF A COLD
FRONT OVER THE CENTRAL ATLC WHICH ENTERS THE AREA NEAR 32N35W
AND EXTENDS SW ALONG 24N44W TO 21N62W. PREFRONTAL SURFACE TROUGH
EXTENDS FROM 24N39W 29N32W TO BEYOND 32N30W. BANDS OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120 NM E OF THE FRONT
AND TROUGH N OF 25N. SHOWER/THUNDERSTORM ACTIVITY SHOULD
CONTINUE ALONG AND E OF THESE FEATURES FOR THE NEXT 24 HOURS
WHEN THE UPPER TROUGH BEGINS TO LIFT NE. W OF THE FRONT...HIGH
PRESSURE AND POST-FRONTAL NW FLOW PREVAILS WITH THE TYPICAL COLD
AIR STRATOCUMULUS CLOUDS PREVAILING TO 65W. THE E ATLC REMAINS
RELATIVELY DRY/TRANQUIL WITH LATEST SATELLITE IMAGERY SHOWING
NEARLY CLOUD FREE CONDITIONS S OF 23N E OF 35W IMPLYING VERY DRY
AIR AND THE SAHARAN DUST HAS OVERSPREAD THE AREA. LOOKING
UPSTREAM...COMPLEX SURFACE LOW/FRONT OVER THE GULF IS EXPECTED
TO LIFT NE ACROSS N FLORIDA AND STRENGTHEN LATER THIS MORNING
SWEEPING A COLD FRONT INTO THE W ATLC BY EARLY FRI. INCREASING
CLOUDINESS IS ALREADY NOTED OVER THE EXTREME NW ATLC WATERS WITH
SHOWERS/THUNDERSTORMS ALREADY SPREADING N OF 28N W OF 75W.

$$
WALLACE



WWWW
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