[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 171149
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST THU 17 FEB 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 6N10W 3N15W 2N25W S OF THE EQUATOR
NEAR 30W TO THE COAST OF SOUTH AMERICA NEAR 43W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM OF THE AXIS
FROM 16W-29W AND FROM 1N TO S OF THE EQUATOR FROM 18W-20W.
CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 6N TO S OF
THE EQUATOR FROM 30W-52W.

...DISCUSSION...

GULF OF MEXICO INTO THE W ATLANTIC W OF 75W...
IN THE UPPER LEVELS...BROAD RIDGING DOMINATES THE GULF AND W
ATLC W OF 75W WITH THE AXIS ALONG 93W AND UPSTREAM PACIFIC
MOISTURE RIDING UP AND OVER THE RIDGE ACROSS THE S UNITED STATES
AND BACK DOWN OVER THE W ATLC. AS A RESULT...STRONG SUBSIDENCE
AND DRY/STABLE AIR ALOFT PREVAILS CAPPING SIGNIFICANT
CLOUDS/CONVECTION OVER THE GULF. AT THE SURFACE...A RIDGE
EXTENDS FROM 32N60W SW TO A 1019 MB HIGH NEAR 29N65W ACROSS S
FLORIDA TO A 1017 MB HIGH IN THE E GULF NEAR 27N87W RESULTING IN
RETURN FLOW OVER THE GULF PRODUCING WARM TEMPERATURES. THE RIDGE
IS PUSHING E AHEAD OF THE NEXT COLD FRONT WHICH IS PRESENTLY
ALONG THE N GULF COAST FROM THE FLORIDA PANHANDLE NEAR PENSACOLA
TO THE TEXAS COAST NEAR 29N96W WITH A STATIONARY FRONT EXTENDING
ALONG THE E SLOPES OF THE SIERRA MADRE MOUNTAINS. THE FRONT IS
PRIMARILY DRY AND IS ONLY PRODUCING OVERCAST LOW CLOUDS WITH
POSSIBLE ISOLATED SHOWERS WITHIN 75 NM ALONG THE COAST W OF
PANAMA CITY FLORIDA AND N OF CORPUS CHRISTI TEXAS. THE FRONT IS
ACCOMPANIED BY A MODERATE SURGE OF CONTINENTAL AIR. PATCHES OF
FOG ARE ALONG THE COAST FLORIDA E OF THE FRONT.

CARIBBEAN...
MID/UPPER LEVEL RIDGE REMAINS IN PLACE OVER CENTRAL AMERICA
WITH AXIS EXTENDING FROM COLOMBIA TO THE YUCATAN PENINSULA. THE
GREATER ANTILLES W OF CENTRAL CUBA INCLUDING JAMAICA ARE UNDER A
BROAD/FLAT TROUGH EXTENDING S FROM THE W ATLC RESULTING IN ZONAL
FLOW OVER MOST OF THE E CARIBBEAN. STRONG SUBSIDENCE AND
DRY/STABLE AIR ALOFT CONTINUES TO DOMINATE THE ENTIRE CARIBBEAN
LIMITING SIGNIFICANT WEATHER TO SHALLOW TOPPED SHOWERS WITHIN A
COUPLE OF POCKETS OF LOW LEVEL MOISTURE. AN AREA OF ISOLATED
SHOWERS IS NOTED OVER THE NE CARIBBEAN N OF 15N E OF 67W TO OVER
THE LEEWARD ISLANDS N OF LOW LEVEL TROUGH EXTENDING FROM A 1008
MB LOW IN THE CENTRAL ATLC TO 13N64W. NORTH FLOW IS PRODUCING
OVERCAST CLOUDS AND SHOWERS OVER PORTIONS OF W PANAMA AND COSTA
RICA EXTENDING OUTWARD TO WITHIN 30 NM OF THE COAST.

ATLANTIC E OF 75W...
THE BULK OF THE ATLC WATERS FEATURES A FLAT UPPER LEVEL TROUGH
WITH NEAR ZONAL FLOW. SHORTWAVE TROUGH OVER THE W ATLC IS
PRODUCING AN AREA OF MID/HIGH CLOUDS N OF 26N BETWEEN 55W-73W.
THIS ACTIVITY IS EXPECTED TO CONTINUE TO MIGRATE E ACROSS
BERMUDA DURING THE NEXT 6 TO 12 HOURS. AT THE SURFACE...A HIGH
PRESSURE RIDGE DOMINATES FROM E OF BERMUDA SW OVER THE N BAHAMAS
AND S FLORIDA. OVER THE CENTRAL ATLC...SURFACE LOW IS CENTERED
NEAR 20N57W WITH A SURFACE TROUGH EXTENDING NE ALONG 25N50W TO
29N40W AND SW FROM THE LOW TO OVER THE LESSER ANTILLES. THIS LOW
IS EXPECTED TO LIFT NE DURING THE NEXT 12 TO 24 HOURS AND IS
PRODUCING SHOWERS/ISOLATED THUNDERSTORMS WITHIN 150/200 NM OF
LINE FROM 30N42W TO THE LOW NEAR 21N54W. OVER THE E ATLC...A
ZONALLY ELONGATED MID/UPPER LOW HAS BECOME STRETCHED ALONG A
LINE FROM N OF THE CANARY ISLANDS NEAR 30N18W TO BEYOND 33N29W
WITH SURFACE REFLECTION IN THE FORM OF A SURFACE TROUGH FROM
28N21W TO 32N28W. SHOWER ACTIVITY CONTINUES TO BE NONEXISTENT.
FURTHER S...VISIBLE SATELLITE IMAGERY STILL SHOWS AN AREA OF
AFRICAN DUST WITH VISIBILITY POSSIBLY RESTRICTED S OF THE CAPE
VERDE ISLANDS TO THE ITCZ E OF 30W.

$$
WALLACE



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