[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 111033
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED APR 11 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
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
1030 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 6N10W 4N20W 3N30W 1N40W EQ47W 1S51W.
SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 240 NM N OF
THE AXIS W OF 41W. SCATTERED MODERATE IS WITHIN 180 NM EITHER
SIDE OF AXIS BETWEEN 31W-41W. ISOLATED MODERATE IS WITHIN 180 NM
N OF THE AXIS E OF 26W.

...DISCUSSION...

GULF OF MEXICO AND SW ATLC...
THE VERY ACTIVE WEATHER HAS NOW MOSTLY SHIFTED INTO THE SW ATLC
WITH LEFT OVER SHOWERS AND TSTMS STILL LYING OVER THE SE GULF
AND SOUTH FLORIDA. DOPPLER RADAR STORM TOTAL RAINFALL ESTIMATES
SHOW A SWATH OF 2-4 INCHES ACROSS EXTREME S FLA WITH UP TO 8
INCHES LOCALLY. THE MAIN PLAYER IS AN UPPER SHORTWAVE WHICH
CONTINUES TO SHIFT E NOW STRETCHING FROM SRN MISSISSIPPI TOWARD
THE YUCATAN CHANNEL. UPPER DIFFLUENCE TO THE E OF THIS AXIS IS
PROVIDING THE SUPPORT FOR THE SHOWERS AND TSTMS N OF 24N BETWEEN
70W-80W AND FROM 24N-27N BETWEEN 80W-86W. THE HEAVIEST RAINFALL
IS CONCENTRATED FROM 25N-27N BETWEEN 75W-79W...WHICH INCLUDES
THE WRN BAHAMAS. THIS CONCENTRATION OF RAIN IS BEING ENHANCED BY
A NEWLY FORMED 1009 MB SFC LOW ANALYZED NEAR 27N78W. A
STATIONARY FRONT EXTENDS N AND E OF THE LOW ALONG 30N76W TO NEAR
BERMUDA. A SFC TROUGH IS ANALYZED S AND W OF THE LOW ALONG
25N80W 25N87W. WHILE THIS LOW IS NOT EASILY IDENTIFIABLE IN THE
DATA...THE ORGANIZATION OF THE FRONTAL STRUCTURE SUGGESTS A WAVE
OF LOW PRES. THIS LOW AND FRONT LIES TO THE S...WARM SECTOR...OF
ANOTHER STATIONARY OR SLOW MOVING WARM FRONT DRAPED ACROSS N AND
CENTRAL FLA. THERE IS A FAIRLY GOOD SWD DIP IN THIS FRONTAL
SYSTEM OVER CENTRAL FLA CLOSELY FOLLOWING THE SFC OBS. MUCH
QUIETER WEATHER IS IN PLACE ACROSS THE CENTRAL AND WRN GULF...W
OF 86W...AS ABUNDANT DRY SINKING AIR TO THE W OF THE SHORTWAVE
AXIS DOMINATES.

COMPUTER MODELS SHOW THE MOISTURE SWATH CONTINUING ITS EWD PUSH
WITH THE UPPER SHORTWAVE AND SFC LOW OVER THE NEXT COUPLE OF
DAYS. A WEAK COLD FRONT IS EXPECTED TO ENTER THE NW GULF LATER
THIS MORNING AND BECOME DIFFUSE ON THU AS IT HEADS SE. ANOTHER
COLD FRONT...THIS ONE EXPECTED TO BE MUCH STRONGER...IS FORECAST
TO MOVE INTO THE NW GULF FRI NIGHT/EARLY SAT INCREASING THE
CHANCE OF RAIN AHEAD OF IT AND BRINGING ABOUT A6 MUCH COOLER
AIRMASS THIS WEEKEND.

THE CARIBBEAN SEA...
A BROAD MID TO UPPER LEVEL RIDGE COVERS THE REGION ANCHORED BY
AN UPPER HIGH CENTERED OVER THE S CENTRAL CARIB NEAR 12N74W.
DIFFLUENCE ON THE W SIDE OF THIS UPPER ANTICYCLONE IS ENHANCING
SCATTERED SHOWERS AND ISOLATED TSTMS OVER COLOMBIA
...PANAMA...COSTA RICA AND NICARAGUA. SIMILAR ACTIVITY IS OVER
THE YUCATAN CHANNEL AND WRN CUBA ASSOCIATED WITH UPPER ENERGY
AHEAD OF A SHORTWAVE TROUGH IN THE GULF. IT SHOULD BE NOTED THAT
THIS ACTIVITY HAS BEEN ON THE WEAKENING TREND OVER THE PAST FEW
HOURS EXCEPT FOR THE RECENT BURSTS OVER COLOMBIA. A BROKEN LAYER
OF CIRRUS...ADVECTED BY UPPER SWLY FLOW...LIES ROUGHLY BETWEEN
78W-86W. ELSEWHERE...MODEST SUBSIDENCE ALONG AND TO THE E OF THE
RIDGE AXIS IS KEEPING CONDITIONS FAIRLY TRANQUIL. AT THE
SFC...HIGH PRES NE OF THE AREA IS PRODUCING MODERATE ELY TRADES
ACROSS THE E AND CENTRAL CARIB VEERING TO THE SE IN THE NW CARIB
IN RESPONSE TO THE FRONTAL SYSTEM IN THE GULF. LOW-LEVEL
MOISTURE PATCHES REMAIN VERY THIN SO OUTSIDE OF THE AREAS
OUTLINED FAIR SKIES ARE THE RULE. NO SIGNIFICANT CHANGES ARE
EXPECTED OVER THE NEXT COUPLE OF DAYS AS MOST OF THE WX FEATURES
REMAIN N OF THE REGION.

CENTRAL AND EASTERN ATLANTIC...
A MODERATE SFC RIDGE WITH THREE EMBEDDED HIGH CENTERS CONTROL
THE PATTERN ACROSS THIS AREA PRODUCING A LARGE AREA OF MODERATE
TRADES IN THE TROPICS. IN THE MID AND UPPER LEVELS...THE FLOW IS
FAIRLY ZONAL IN THE SUBTROPICS WITH PATCHES OF MID AND HIGH
LEVEL CLOUDS MOSTLY N OF 22N W OF 22W. THE FLOW THEN
CURVES MORE TO THE N IN THE TROPICS W OF 35W AROUND A BROAD
RIDGE CENTERED IN THE S CARIB KEEPING CONDITIONS RATHER
TRANQUIL. FARTHER EAST...SUBSTANTIAL DRY AIR LIES IN AN UPPER
CONFLUENT ZONE TO THE S OF A STRONG UPPER LOW 240 NM W OF
PORTUGAL. THIS LOW HAS ASSOCIATED TROUGHING THAT EXTENDS WELL SW
ALONG 32N15W 15N20W 4N38W. A 100-120 KT JET ORIGINATES AT THE
BASE OF THIS TROUGH AND RACES NE TO THE COAST OF AFRICA NEAR
20N16W. A PLUME OF MOISTURE LIES TO THE SE OF THE JET AXIS WHILE
UPPER CONFLUENCE IS ENHANCING DRY AIR TO THE W OF THE AXIS. THIS
JET IS ALSO PROVIDING A FAVORABLE ENVIRONMENT FOR CONVECTION IN
THE ITCZ WHICH IS PARTICULARLY ACTIVE W OF 40W.

$$
CANGIALOSI


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