[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 071800
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST MON FEB 07 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.

...ITCZ...

ITCZ AXIS WAS ANALYZED FROM NEAR THE EQUATOR NEAR 00N13W TO
02N20W TO 01N27W TO 02.5N34W TO 03N45W TO COASTAL PORTIONS OF
FAR N BRAZIL NEAR 03N51W. HOWEVER...TWO DISTINCT LINES OF
SIGNIFICANT CONVECTION ACROSS THE EQUATORIAL ATLANTIC SUGGEST A
DOUBLE ITCZ STRUCTURE...AND THIS IS LIKELY TO BE REFLECTED ON
THE 1800 UTC ANALYSIS. SCATTERED MODERATE TO STRONG CONVECTION
WAS OCCURRING WITHIN 150 NM S OF THE AXIS BETWEEN 13W AND
30W...WHILE SCATTERED MODERATE CONVECTION WAS OCCURRING WITHIN
330 NM N OF THE AXIS ACROSS THIS SAME AREA. SCATTERED TO
NUMEROUS MODERATE TO STRONG CONVECTION WAS OCCURRING BETWEEN 05N
AND 02S BETWEEN 30W AND 48W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD LONGWAVE TROUGH CONTINUES ACROSS MOST OF THE CONTINENTAL
U.S. TODAY...WITH A SHARP MID TO UPPER LEVEL TROUGH SWEEPING EWD
ACROSS THE CENTRAL U.S. FROM THE CENTRAL PLAINS S-SW THROUGH ERN
TEXAS AND INTO NE MEXICO NEAR 23N99W. A SW JETSTREAM WAS LOCATED
E OF THE TROUGH EXTENDING FROM THE SW GULF NE ACROSS THE FLORIDA
BIG BEND REGION...WITH CORE WIND VELOCITIES OF 100 TO 150 KT
MOVING ACROSS NW FLORIDA AND THE SE U.S. COASTAL ZONES. AT LOW
LEVELS...THE ACCOMPANYING SCENARIO HAS BECOME QUITE COMPLEX. AN
OLD FRONTAL BOUNDARY LINGERING ACROSS THE GULF FOR DAYS HAS
LIFTED FROM THE SE GULF NWD DURING THE PAST 24 HOURS...AND WAS
ANALYZED AS A WARM FRONT E TO W ACROSS N FLORIDA...JUST S OF
OCALA...EXTENDING W TO A DEVELOPING 1011 MB LOW NEAR 28.5N86W.
THE WARM FRONT CONTINUED W...AND HAD BEGUN TO MERGE WITH A NEW
COLD FRONTAL BOUNDARY MOVING QUICKLY SE ACROSS THE NW GULF. A
SECOND LOW 1012 MB WAS RIDING NE ALONG THIS BOUNDARY AND WAS
LOCATED AT THE JUNCTION OF THE NEW COLD FRONT AND THE WARM
FRONT...JUST OFF THE MOUTH OF THE MISSISSIPPI NEAR 29N88.5W.
THIS NEW COLD FRONT WAS RACING E-SE NEAR 28 KT OFF THE LOUISIANA
COAST AND EXTENDED FROM THE 1012 MB LOW  TO THE SW GULF NEAR
23N96W TO THE MEXICAN COAST JUST N OF TUXPAN. A WEAK FRONTAL
TROUGH ALSO EXTENDED SW FROM THE 1011 MB LOW ALONG THE WARM
FRONT...TO THE CENTRAL BAY OF CAMPECHE...AND WAS GENERALLY
PARALLEL TO THE NEW COLD FRONT. STRONG LOW TO MID LEVEL
CONVERGENCE OCCURRING E OF THIS WEAK FRONTAL TROUGH AND S OF THE
WARM FRONT WAS INITIATING A NEARLY SOLD LINE OF STRONG
CONVECTION WITHIN 90 NM SE OF THE FRONTAL TROUGH AND N OF 27N.
THE LIGHTNING DETECTION NETWORK SHOWED NUMEROUS AND FREQUENT
LIGHTNING STRIKES WITHIN THIS LINE OF CONVECTION. THE 100+ KT
JET ACROSS THE NE GULF WAS ACTING TO ENHANCE THIS CONVECTION.
LOOK FOR THIS VERY ACTIVE TSTORM ACTIVITY TO SHIFT NE ACROSS THE
REMAINDER OF THE NE GULF AND NRN FLORIDA THIS AFTERNOON AND
EVENING WITH THE POTENTIAL FOR VERY HEAVY RAINFALL AND SEVERE
WEATHER.

THIS SECOND NEW COLD FRONT WILL CONTINUE TO SWEEP E TO SE ACROSS
THE GULF THIS AFTERNOON AND EVENING AND GRADUALLY OVERTAKE THE
LEADING FRONTAL TROUGH TUESDAY MORNING...ACROSS THE SW N ATLC
AND NW CARIBBEAN. THIS SECONDARY FRONT FOLLOWED BY A NWLY SURGE
OF COLD AIR IS EXPECTED TO REACH FROM NEAR PENSACOLA TO NW BAY
OF CAMPECHE THIS EVENING AND EXIT THE BASIN SHORTLY AFTER
MIDNIGHT TONIGHT. NW SURFACE WINDS OF 25 TO 30 KT CURRENTLY
AFFECTING THE NW GULF WILL SPREAD S AND SE THIS EVENING BEFORE
GRADUALLY ABATING TONIGHT.

CARIBBEAN SEA...
WATER VAPOR IMAGERY INDICATES VERY DRY AIR ALOFT ACROSS MOST OF
THE BASIN DUE TO A TUTT AXIS EXTENDING E TO W ALONG 13N. THE
TUTT AXIS INTERACTING WITH THE UPPER LEVEL RIDGE IN THE NW ATLC
IS PULLING MOISTURE TO THE NW. ENHANCED MOISTURE FROM THE
TROPICAL ATLANTIC HAS MOVED IN WITH THE MODERATE TO FRESH
EASTERLY TRADES BEGINNING TO TURN CYCLONICALLY AROUND THE
COLOMBIAN COAST....WITH WINDS 25-30 KT IN THE SW CARIBBEAN...
PROVIDING WEAK SCATTERED SHOWERS ACROSS THE EASTERN BASIN E OF
70W. SIMILAR ACTIVITY IS HAPPENING OVER THE N CENTRAL BASIN N OF
16N BETWEEN 74W AND 78W. THE TRADES ARE ALSO BANKING MOISTURE
AGAINST CENTRAL AMERICA WITH SCATTERED SHOWERS FROM 12N-19N
BETWEEN 82W AND 85W. TYPICAL UPSLOPE YET SHALLOW CONVECTION
SHOULD BE EXPECTED ACROSS THE CARIBBEAN COASTS OF CENTRAL
AMERICA THROUGH THIS EVENING.

ATLANTIC OCEAN...
UPPER LEVEL TROUGHING ACROSS THE CENTRAL AND NE CONUS IS
SUPPORTING A NEARLY STATIONARY FRONT THAT ENTERS THE AREA NEAR
32N72W AND EXTENDS SW TO THE FLORIDA PENINSULA NEAR 28N80W.
MOSAIC DOPPLER RADAR IMAGERY INDICATES MID-LEVEL MOISTURE
OVERRUNNING THE FRONTAL BOUNDARY PRODUCING NARROW BANDS OF
SHALLOW SCATTERED SHOWERS WITHIN 180 NM NW OF THE FRONT. THE
REMAINDER OF THE AREA IS UNDER THE INFLUENCE OF A 1027 MB HIGH
CENTERED NEAR 28N50W. A DISSIPATING COLD FRONT ENTERS THE
SURFACE RIDGE IN THE NE ATLC NEAR 32N25W AND BECOMES AND
DISSIPATING STATIONARY FRONT NEAR 28N32W TO 30N38W WITH POSSIBLE
SHOWERS WITHIN 60 NM OF THE FRONTAL BOUNDARY. A MODERATE PRES
GRADIENT IS ACROSS THE TROPICAL ATLC...YIELDING NELY TRADES OF
20-25 KT S OF 21N FROM 28W TO JUST E OF THE LESSER ANTILLES. THE
LOW TO MID LEVEL REMNANTS OF A TUTT INDUCED TROUGH...AND ITS
ASSOCIATED ENHANCED MOISTURE...IS PRODUCING SCATTERED CLUSTERS
OF TRADEWIND SHOWERS THAT WILL BE ENHANCED AS THEY MOVE ACROSS
THE ISLANDS THIS AFTERNOON AND EVENING. EAST OF 30W S OF 20N AND
E OF 22W N OF 20N...DRY AND STABLE SAHARAN AIR DOMINATES
YIELDING NEARLY CLOUD FREE SKIES. TO THE W OF THIS SAHARAN AIR.

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

$$
STRIPLING/MONTALVO




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