[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 091743
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED JAN 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 3N10E EQ5W 3N22W 2N40W EQ50W.
SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF THE AXIS
BETWEEN 1W-5W AND FROM 3N-7N BETWEEN 33W-42W. SCATTERED MODERATE
BUT WEAKENING CONVECTION IS WITHIN 90 NM OF THE AXIS BETWEEN
14W-25W.

...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT CONTINUES SLOW PROGRESS FROM THE THE WRN FLORIDA
PANHANDLE TO 27N94W THEN STATIONARY SWD INTO THE W BAY OF
CAMPECHE ENDING NEAR 18N95W. LOW TO MID LEVEL CLOUDINESS AND
EMBEDDED SCATTERED SHOWERS ARE WITHIN 150 NM BEHIND THE FRONT.
THE UPPER TROUGH SUPPORTING THE FRONT REACHES A BASE OVER THE
LOWER MISSISSIPPI VALLEY. NUMERICAL MODELS SHOW THIS UPPER
SHORTWAVE MOVING QUICKLY E AND FLATTENING CAUSING THE FRONT TO
WEAKEN AND STALL LATER TODAY. AHEAD OF THE FRONT...WEAK SFC HIGH
PRES CENTERED OVER OR JUST E OF CENTRAL FLORIDA IS PRODUCING
LIGHT TO MODERATE E TO SE WINDS ACROSS THE SE GULF VEERING S
NEAR THE FRONT. A FEW PATCHES OF SHOWER ACTIVITY LIE OVER THE
MID-GULF FROM 24N-28N BETWEEN 87W-91W. SHIP/BUOY DATA SHOW SOME
EVIDENCE OF A WEAK E-W SFC TROUGH ALONG 88W WHICH MAY BE THE
CULPRIT FOR THIS PATCHY ACTIVITY.

CARIBBEAN SEA...
BROAD ELONGATED MID TO UPPER RIDGING ENTRENCHED IN MODERATE TO
STRONG SUBSIDENCE DOMINATES THE PATTERN ACROSS THE CARIBBEAN.
THE DRIEST AIR ALOFT IS N OF 17N E OF 76W WHERE THE UPPER FLOW
IS MOST CONFLUENT TO THE S OF AN UPPER LOW IN THE CENTRAL ATLC.
THIS STABLE ENVIRONMENT IS PREVENTING THE TYPICAL LOW-LEVEL
CLOUD PATCHES ACQUIRE SIGNIFICANT VERTICAL DEPTH. THE ONLY
ORGANIZED CLOUDINESS/SCATTERED SHOWERS IS OVER THE FAR SE CORNER
S OF 14N E OF 65W...INCLUDING THE WINDWARD ISLANDS. TRADE WINDS
HAVE DECREASED SOME SINCE YESTERDAY BUT REMAIN ON THE STRONG
SIDE NEAR THE COAST OF COLOMBIA. THESE WINDS ARE EXPECTED TO
SUBSIDE FURTHER OVER THE NEXT DAY OR TWO AS SFC TROUGHING SHIFTS
N OF THE AREA.

ATLANTIC OCEAN...
MAIN FEATURE IN THE ATLC DISCUSSION AREA IS A FAIRLY LARGE UPPER
CUT OFF LOW CENTERED NEAR 29N58W. AN ASSOCIATED WWD MOVING SFC
TROUGH IS ANALYZED FROM 28N50W TO 20N54W...CAPTURED FAIRLY WELL
BY A RECENT ASCAT PASS. COMBINATION OF UPPER DIFFLUENCE TO THE E
OF THE UPPER LOW AND LOW-LEVEL CONVERGENCE NEAR THE SFC BOUNDARY
IS PRODUCING SCATTERED SHOWERS AND ISOLATED TSTMS FROM 24N-30N
BETWEEN 40W-57W. SIMILARLY...DIFFLUENCE ALOFT TO THE E OF THE
INDUCED TROUGH BASE IS PRODUCING A SWATH OF MID-HIGH LEVEL
CLOUDINESS AND EMBEDDED SHOWERS FROM 12N-22N BETWEEN 38W-53W.
THE W ATLC IS VERY TRANQUIL THIS AFTERNOON SUPPORTING BY A
SUBSIDENT MID-UPPER RIDGE CENTERED OVERHEAD. THE E ATLC IS ALSO
TRANQUIL UNDER PREDOMINATELY ZONAL FLOW ALOFT. VISIBLE IMAGERY
SHOWS A PLUME OF CLOUD FREE AIR LIKELY ASSOCIATED WITH SAHARAN
DUST...AS NOTED IN THE CIMSS SAL PRODUCT...MOVING W THRU THE
CAPE VERDE ISLANDS TO ABOUT 28W.

SFC ANALYSIS SHOWS A STRONG BERMUDA-AZORES RIDGE IN CONTROL
ENHANCING STRONG NE WINDS TO THE NW OF THE AFOREMENTIONED SFC
TROUGH IN THE CENTRAL ATLC. ELY TRADES ARE MODERATE ELSEWHERE.

$$
CANGIALOSI






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