[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171157
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 5N5W 3N10W 4N16W 2N25W 4N46W 2N51W.
SCATTERED/NUMEROUS STRONG CONVECTION IS WITHIN 90/120 NM OF THE
AXIS FROM 18W-23W...FROM 30W-44W...AND WITHIN 60 NM 2N FROM
13W-17W. ISOLATED CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE FROM 5N TO S OF THE EQUATOR BETWEEN 24W-47W.

...DISCUSSION...

GULF OF MEXICO...
COMPLEX PATTERN CONTINUES OVER THE GULF AS S STREAM SHORTWAVE
TROUGH MOVES ACROSS MEXICO INTO E 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 ENHANCING THE
AREA OF NUMEROUS SHOWERS/THUNDERSTORMS TO OVER THE NE GULF AND
FLORIDA PENINSULA. AT THE SURFACE...COLD FRONT EXTENDS FROM A
1004 MB LOW IN THE W ATLC NEAR 33N76W TO A WEAKENING 1006 MB LOW
ALONG THE COAST OF THE FLORIDA PANHANDLE NEAR 30N85W INTO THE
GULF ALONG 24N88W TO OVER S MEXICO NEAR 18N93W. A STATIONARY
FRONT EXTENDS 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 12 TO 24 HOURS. THE STRONGEST
SHOWERS/THUNDERSTORMS ARE WITHIN 90 NM OF LINE FROM N OF THE
YUCATAN PENINSULA TO OVER THE N FLORIDA PENINSULA. THE FRONT IS
THEN EXPECTED TO CLEAR S FLORIDA BY TONIGHT 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 JUST W
OF THE ABC ISLANDS WITH BROAD ANTICYCLONIC FLOW COVERING THE
GULF OF MEXICO...CARIBBEAN...AND THE W ATLC W OF 45W.
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 IS INCREASING CLOUDINESS
WITH SHOWERS/THUNDERSTORMS MOVING INTO THE YUCATAN CHANNEL AND
OVER W CUBA THIS MORNING.

ATLANTIC...
LARGE AMPLITUDE RIDGE-TROUGH-RIDGE PATTERN PREVAILS OVER THE
SUBTROPICAL ATLANTIC WITH A BROAD MID/UPPER LEVEL RIDGE W OF
45W...DEEP LAYERED TROUGH OVER THE CENTRAL ATLC BETWEEN
24W-45W...AND RIDGE OVER THE E ATLC E OF 24W 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 32N34W
AND EXTENDS SW TO 22N45W WHERE IT DISSIPATES TO 20N60W.
PREFRONTAL SURFACE TROUGH EXTENDS FROM 24N42W 26N32W TO 32N27W.
BAND OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120
NM E OF THE TROUGH N OF 26N. SHOWER/THUNDERSTORM ACTIVITY IS
MOVING NE AND WILL CONTINUE OUT OF THE REGION WITHIN THE NEXT 12
TO 24 HOURS. W OF THE FRONT...HIGH PRESSURE AND POST-FRONTAL NW
FLOW PREVAILS WITH THE TYPICAL COLD AIR STRATOCUMULUS CLOUDS
PREVAILING TO 60W. THE E ATLC REMAINS RELATIVELY DRY/TRANQUIL
WITH LATEST VISIBLE SATELLITE IMAGERY SHOWING NEARLY CLOUD FREE
CONDITIONS FROM 6N-20N 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 CONTINUE 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 26N W OF 70W.

$$
WALLACE


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