[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 041804
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST FRI FEB 04 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND 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...
SATELLITE IMAGERY AND GFS ANALYSIS SUGGEST THE AXIS EXTENDS FROM
COASTAL GULF OF GUINEA MEANDERING W-SW TO 01N16W TO NEAR THE
EQUATOR ALONG 27W TO THE COAST OF S AMERICA NEAR 03S43W. ACTIVE
CNVTN WAS OCCURRING N OF THIS ANALYZED ITCZ...WHERE SCATTERED TO
NUMEROUS MODERATE TO STRONG CNVTN WAS NOTED WITHIN 240 NM N OF
THE AXIS...WHILE SCATTERED MODERATE TO STRONG CNVTN WAS NOTED
WITHIN 180 NM S OF THE AXIS AND EXTENDED ACROSS THE EQUATOR INTO
THE SRN HEMI BETWEEN 24W AND 35W. SCATTERED CLUSTERS OF DEEP
CNVTN WERE OCCURRING ALONG COASTAL PORTIONS OF THE GULF OF
GUINEA...S OF THE MONSOON TROUGH.

...DISCUSSION...

THE GULF OF MEXICO...
THE BROAD RIDGE ACROSS THE GULF HAS SHIFTED E TO ALONG 70W THIS
MORNING AS DEEP LAYERED CYCLONE ACROSS THE SW U.S. AND OKLATEX
REGION HAS REORGANIZED OVERNIGHT AND BECOME MORE NE TO SW
ELONGATED. THE LINGERING FRONTAL BOUNDARY ACROSS THE GULF
REMAINS DIFFICULT TO IDENTIFY PRECISELY...BUT HAS DRIFTED NW
ACROSS N AND NE PORTIONS OF THE GULF AND INTO THE GULF STATES
COASTAL WATERS FROM SE LOUISIANA TO THE FLORIDA PANHANDLE. SHARP
CYCLONIC TURNING IN BUOY AND OIL RIG OBS OFF OF MS AND LA COASTS
INDICATE AN E TO W WARM FRONT ACROSS THE NE GULF FROM N OF
TARPON SPRINGS TO JUST E OF THE MOUTH OF THE MISSISSIPPI THEN
STATIONARY FRONT S-SW TO NEAR 26N91W CONTINUING INTO THE CENTRAL
BAY OF CAMPECHE. DENSE OVERCAST LOW AND MIDDLE CLOUD CONTINUE W
OF THE FRONTAL BOUNDARY...PRODUCING FOG...LIGHT RAIN...DRIZZLE
AND SOME FREEZING LIGHT RAINS ACROSS W AND NW PORTIONS.
OVERRUNNING SW FLOW AT MID LEVELS IS PRODUCING A MIXED BAG OF
PRECIPITATION IN MODERATE CONVECTION ACROSS LOUISIANA...MS...AND
ALABAMA SPREADING NE INTO THE SE U.S. AN ASCAT PASS YESTERDAY
SHOWED A SHARP HORIZONTAL WIND GRADIENT IN THE W BAY OF
CAMPECHE...SUGGESTING THE FRONTAL BOUNDARY MAY HAVE REMAINED
THERE FOR THE PREVIOUS 24 HOURS...AND MOST RECENT WIND
OBSERVATION FROM COATZACOALCOS MEXICO IN THE S CENTRAL BAY OF
CAMPECHE WAS FROM THE SOUTH. OUR FRONTAL POSITION FOR THE S END
OF THE FRONT MAY HAVE BEEN TOO FAR E FOR THE PAST 48 HOURS AND
SOME ADJUSTMENTS WILL BE MADE OF THE 18Z MAP. ALTHOUGH PRES
ANALYSIS ACROSS THE GULF THIS MORNING SHOWS BROAD AND ELONGATED
LOW PRES ALONG THE FRONT...THERE IS YET LITTLE EVIDENCE FOR A
SYNOPTIC SCALE LOW AS GLOBAL MODELS HAD BEEN FORECASTING. THE
WAVE OR DOUBLE POINT OFF THE MOUTH OF THE MS WILL BE THE LIKELY
GENESIS REGION FOR ANY FORMATION OF A SURFACE LOW. NW TO N WINDS
OF 20-30 KT PREVAIL TO THE W OF THE FRONT AND W OF 90W...WITH
MINIMAL GALES OVER WRN PORTIONS EARLY THIS MORNING THROUGH LATE
MORNING...WHICH HAVE LIKELY DIMINISHED BY NOW. DEEP LAYERED LOW
MOVING ACROSS THE OKLATEX REGION IS FORECAST BY GLOBAL MODELS TO
ELONGATE WITH JET ENERGY LIFTING OUT TO THE NE NEXT 24 HOURS...
WITH ANOTHER SURFACE LOW BEING GENERATED AND MOVING IN SYNC.
THIS WILL PROVIDE SUPPORT TO MOVE THE COLD FRONT CURRENTLY
STALLED ACROSS THE GULF...AND DRAG IT E AND SE ACROSS THE
BASIN...WITH A NEWLY INVIGORATED COLD FRONT EXPECTED TO REACH
FROM THE FLORIDA BIG BEND REGION SW TO THE ERN BAY OF CAMPECHE
BY SAT MORNING. NORTHERLY FLOW OF 20-25 KT IS FORECAST TO SPILL
ACROSS THE W HALF OF THE BASIN TO OFFSHORE OF THE MOUTH OF THE
MS TONIGHT BEHIND THE EWD MOVING BOUNDARY AND THEN DIMINISH
QUICKLY BY FRI AFTERNOON AS HIGH PRES MOVES INTO THE NW GULF.

THE CARIBBEAN SEA...
SINKING AIR AND SUBSIDENCE CONTINUES TO DOMINATED ALL BUT THE
FAR NW PORTIONS OF THE CARIB BASIN...ON THE S SIDE OF THE GULF
OF MEXICO UPPER RIDGE. WATER VAPOR IMAGERY REVEALS A MID LEVEL
TROUGH AXIS MEANDERING FROM THE CENTRAL ATLC DEEP LAYERED LOW TO
NEAR 10N61W THEN CONTINUES WWD TO A WEAKENING MID LEVEL CYCLONE
NEAR 11N77W. FAIR WEATHER AND MODERATE TO FRESH E-NE TRADES THUS
DOMINATE THE BASIN. RECENT SCATTEROMETER PASSES SHOW STRONGEST
TRADES CONTINUING FROM S AND SW OF THE MONA PASSAGE TO OFFSHORE
OF COLOMBIA AT AROUND 25 KT...WITH WINDS 30 TO NEAR 35 KT WITHIN
120 NM OF THE COLOMBIA COAST. DEEP LAYERED TROUGH E OF THE
LESSER ANTILLES HAS CARVED OUT A BROAD SURFACE REFLECTION IN THE
PAST FEW DAYS...HELPING TO PRODUCE A DECIDEDLY NE FLOW ACROSS
THE E AND SE CARIB. A FEW CLUSTERS OF SHALLOW MOISTURE AND
MODERATE SHOWERS WERE SEEN EMBEDDED IN THESE TRADES MOVING WSW
ACROSS THE BASIN. LITTLE CHANGE IN THE OVERALL LLVL PATTERN IS
EXPECTED THROUGH FRI MORNING...WITH AN INCREASE IN MOISTURE AND
SHOWERS EXPECTED ACROSS THE NE CARIB BY MIDDAY FRI.

THE ATLANTIC OCEAN...
AS STATED ABOVE...UPPER RIDGING ACROSS THE GULF OF MEXICO HAS
SHIFTED E TO ALONG 70W...YIELDING MID TO UPPER CONVERGENCE AND
SINKING MOTION S OF 27N AND W OF 60W. GENERALLY ZONAL FLOW
PREVAILS N OF THE AREA OVER THE RIDGE...WITH A TUTT AXIS
EXTENDING FROM A MID TO UPPER CYCLONE NEAR 34N23W TO THE
CENTRAL ATLC DEEP LAYERED TROUGH AND WEAKENING CYCLONE NEAR
17.5N53W. STRONG DIRECTIONAL CONVERGENCE ALONG THE ITCZ
CONTINUES TO YIELD GOOD CONVECTION OFF FROM 01N TO 05N E OF 40W
AND IS MAINTAINING THE UPPER RIDGING S OF THE TUTT. HOWEVER
CONVECTION HAS DIMINISHED IN THE PAST HOUR OR SO. GULF FRONTAL
BOUNDARY WAS ILL DEFINED ACROSS FLORIDA...BUT STRETCHED ACROSS N
FLORIDA SW TO NW...WITH A SMALL WEAK LOW ALONG THE FRONT NEAR
31N79W MOVING E-NE...AND WEAK ANTICYCLONIC FLOW TO THE E. THIS
WEAK HIGH WAS TRAPPED TO THE S OF AN OLD FRONTAL BOUNDARY
STRETCHED OUT ACROSS N PORTIONS OF THE AREA FROM THE SURFACE LOW
TO 30N70W TO 33N56W AND BEYOND. EXCEPT FOR SCATTERED MODERATE
CONVECTION OCCURRING ACROSS THE E AND SE SEMICIRCLES OF THE DEEP
LAYERED CENTRAL ATLC TROUGH...HIGH PRES AND FAIR WEATHER
GENERALLY PREVAIL ACROSS THE ATLC OFF THE ITCZ. A 1040 MB HIGH
NEAR NEAR 40N14W ANCHORS THE ATLANTIC HIGH PRES RIDGE.

METEOSAT IMAGERY THIS MORNING SHOWS VERY STABLE NE LLVL FLOW
BLOWING OFF OF W AFRICA TO 30W TURNING CYCLONICALLY INTO THE
WEAK BUT PERSISTENT MONSOONAL CIRCULATION ACROSS TROPICAL
AFRICA. DRY CLEAR AIR CONTINUED OFF THE W COAST OF AFRICA TO THE
CAPE VERDES...WITH ANOTHER PLUME OF AFRICAN DUST SEEN EXITING
THE CONTINENT ALONG 19N.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
STRIPLING





This weather bulletin was brought to you by:
www.nashvilleweather.net