[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 091136
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST SAT FEB 09 2008

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 10N14W 6N20W 1N28W 2N40W THEN
INLAND OVER SOUTH AMERICA NEAR EQ50W. SCATTERED STRONG
CONVECTION IS FROM 2N TO THE COAST OF LIBERIA BETWEEN 7W AND
12W. AREA OF SCATTERED MODERATE TO STRONG CONVECTION IS FROM THE
EQUATOR TO 5N BETWEEN 17W-21W. SMALL CLUSTERS OF SCATTERED
MODERATE CONVECTION ARE NOTED ELSEWHERE WITHIN 120-180 NM OF THE
AXIS BETWEEN 21W-27W AND BETWEEN 32W-45W.

...DISCUSSION...

GULF OF MEXICO...
RESIDUAL EFFECTS OF AN UPPER LEVEL SHEARED TROUGH EXITING THE
ERN U.S. AND OVER THE N-CENTRAL ATLC ARE CONFINED TO S FLORIDA
AND THE FAR SE PORTION OF THE GULF OF MEXICO. THIS IS PROVIDING
LIMITED SUPPORT FOR A DISSIPATING STATIONARY FRONT EXTENDING
FROM 32N71W SOUTHWESTWARD ACROSS THE FLORIDA PENINSULA NEAR LAKE
OKEECHOBEE THEN CONTINUING INTO THE GULF TO NEAR 25N88W.
LIGHTNING DATA INDICATED AN ACTIVE CLUSTER OF THUNDERSTORMS NEAR
THE TAIL END OF THE DISSIPATING FRONT WITHIN 45-60 NM OF 26N87W.
ANOTHER UPPER LEVEL SHORTWAVE TROUGH IS MOVING ACROSS THE
MIDWEST AND EXTENDS SOUTHWARD ACROSS THE TENNESSEE RIVER VALLEY
INTO SRN LOUISIANA AND ERN TEXAS AND WILL MOVE ACROSS THE SE
CONUS LATER TODAY AND SUNDAY. THIS UPPER TROUGH IS PROVIDING
SOME SUPPORT FOR A COLD FRONT WHICH IS EMERGING OFF THE TEXAS
COAST. IN THE UPPER LEVELS...A BROAD AREA OF SWLY UPPER LEVEL
WINDS ARE NOTED OVER THE ENTIRE GULF BETWEEN THE TROUGH AND AN
UPPER RIDGE IN THE CARIBBEAN EXTENDING NEWD INTO THE WRN ATLC.
THE STRONG SW WINDS ALOFT...80-90 KT PER SATELLITE DERIVED WINDS
WERE PROVIDING SOME LIFT FOR THE DEVELOPING AREA OF
THUNDERSTORMS OVER THE E-CENTRAL GULF. THE STATIONARY FRONT IS
EXPECTED TO DISSIPATE TO A TROUGH THIS MORNING. HIGH PRESSURE
WILL BUILD ACROSS GULF THROUGH TONIGHT AND STRENGTHEN SUN/MON
THEN MOVE E OF THE AREA TUE.

CARIBBEAN SEA...
A PERSISTENT UPPER LEVEL RIDGE EXTENDS FROM THE SW CARIBBEAN
ALONG 80W NEWD ACROSS EXTREME ERN CUBA/WINDWARD PASSAGE INTO
THE SE BAHAMAS AND NE ACROSS THE SUBTROPICAL ATLC. A SHEARED
UPPER TROUGH AXIS EXTENDS WWD ACROSS THE TROPICAL ATLC ACROSS
THE NORTHEAST WINDWARD ISLANDS TO JUST S OF HISPANIOLA AND THE
MONA PASSAGE. THE SURFACE RIDGE OVER THE ATLC COUPLED WITH THE
LOWER PRESSURE OVER SOUTH AMERICA IS PRODUCING A RATHER TIGHT
PRESSURE GRADIENT OVER THE SW CARIBBEAN AND IS GENERATING
MODERATE TO STRONG EASTERLY TRADE WINDS ACROSS THE AREA. THE
EDGE OF A 0302 UTC ASCAT PASS INDICATED 20-25 KT WINDS OVER THE
SW CARIBBEAN. MODERATE/STRONG SUBSIDENCE AND DRY AIR UPPER AIR
ARE LIMITING ANY AREAS OF DEEP CONVECTION ACROSS THE AREA.
HOWEVER...THE STRONG TRADE WINDS ARE USHERING IN SOME LOW LEVEL
CLOUDS WITH LOW LEVEL CONVERGENCE MANIFESTING ITSELF IN A PATCH
OF SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WITHIN 60-90 NM
SW OF THE CAYMAN ISLANDS NEAR 18N82W.

ATLANTIC OCEAN...
THE SHEARED UPPER LEVEL TROUGH OVER THE NE US AND N-CENTRAL
ATLC HAS VIRTUALLY DISAPPEARED IN THE WAKE OF AN EXPANSIVE RIDGE
COVERING A MAJORITY OF THE ATLC. THE ONLY MANIFESTATION OF THE
SHEARED TROUGH IS A DISSIPATING STATIONARY FRONT EXTENDING FROM
32N71W TO THE FLORIDA E COAST NEAR STUART. WIDELY SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 45 NM OF THE FRONT
BETWEEN THE FLORIDA E COAST AND 32N. THE FRONT WILL DISSIPATE
LATER TODAY AS A SECOND COLD FRONT IS FORECAST TO MOVE OFF THE
SE US COAST TONIGHT OR EARLY SUNDAY. STRONG HIGH PRESSURE WILL
BUILD SE ACROSS THE W ATLC BEHIND THE SECOND FRONT THROUGH TUE
INCREASING WINDS OVER THE AREA. THE EXPANSIVE RIDGE NOTED ABOVE
DOMINATES THE CENTRAL ATLC N OF 19N BETWEEN 35W AND 78W. AN
EMBEDDED UPPER LEVEL ANTICYCLONE WAS NOTED NEAR 26N55W WITH THE
EXPANSIVE SURFACE RIDGE ANCHORED BY A 1025 MB HIGH NEAR 28N50W.
UPPER LEVEL LOW OVER THE NE ATLC NEAR THE CANARY ISLANDS/28N17W
IS MOVING NE 10-15 KT. STRONGLY POSITIVE TILT TROUGH EXTENDS
FROM THE LOW WSWWD ACROSS 21N30W 18N40W THEN TRANSITIONS TO A
SHEAR AXIS WHICH UNDERCUTS THE STRONG ATLC RIDGE ALONG 19N50W TO
THE NE WINDWARD ISLANDS. AN ASSOCIATED SURFACE TROUGH EXTENDS
FROM A 1007 MB LOW NEAR 28N19W JUST W OF THE WESTERNMOST CANARY
ISLANDS TO 26N16W 21N20W. SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS ARE NOTED OVER THE CANARY ISLANDS FROM 27N-30N
BETWEEN 15W-18W WITH A LARGER AREA OF SHOWERS AND THUNDERSTORMS
WITHIN 45 NM OF A LINE THROUGH 32N16W 30N12W. AN E/W UPPER RIDGE
EXTENDS ACROSS THE TROPICAL ATLC ALONG 5N TO 35W. A STRONG UPPER
LEVEL JETSTREAM WITH WINDS OF 90-140 KT CUTS ALONG THE N
PERIPHERY OF THE RIDGE WITHIN 120 NM OF LINE FROM 14N35W JUST N
OF THE CAPE VERDE ISLANDS THEN INLAND OVER W AFRICA/MAURITANIA
NEAR 21N16W.

$$
COBB





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