[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 152338
TWDAT

TROPICAL WEATHER DISCUSSION...
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE APR 15 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N12W 3N20W 1N30W 1N40W CROSSING THE
EQUATOR NEAR 44W TO 1S48W. SCATTERED MODERATE CONVECTION IS
WITHIN 150 NM N OF THE AXIS BETWEEN 20W-28W AND BETWEEN 39W-43W.
SIMILAR CONVECTION IS WITHIN 180 NM S OF THE AXIS BETWEEN
18W-20W AND BETWEEN 27W-30W.

...DISCUSSION...

GULF OF MEXICO...
AN UNUSUALLY COOL AND DRY AIRMASS FOR MID-APRIL REMAINS IN PLACE
OVER THE ERN HALF OF THE REGION. THE HIGHEST TEMPS REPORTED
WHERE NEAR 70F IN THE FL KEYS...WHICH IS WELL BELOW NORMAL
VALUES. SAT IMAGES SHOW STRATOCUMULUS CLOUDS SCATTERED ABOUT S
OF 29N E OF 90W...INDICATIVE OF THE VERY COOL STABLE AIR. THIS
AIRMASS IS MODIFYING OVER THE WRN WATERS AS THE LOW-LEVEL FLOW
VEERS E ON THE S SIDE OF A 1028 MB HIGH OVER MISSISSIPPI.
ALOFT...AN AMPLIFIED TROUGH IS NEARING THE CUT OFF STAGE JUST E
OF THE GEORGIA COAST WITH ASSOCIATED TROUGHING EXTENDING INTO
THE NE WATERS. UPPER CONFLUENCE IS CREATING A VERY DRY
ATMOSPHERE N OF A LINE FROM HOUSTON TO KEY WEST. ELSEWHERE
...SWIFT ZONAL FLOW IS SPREADING SOME PATCHY HIGH LEVEL PACIFIC
MOISTURE INTO THE BAY OF CAMPECHE. LOOKING AHEAD A DAY OR
SO...THE SFC HIGH AND UPPER TROUGH WILL CONTINUE PUSHING E
ALLOWING A TREND TOWARDS NORMAL TEMPS. MOISTURE SHOULD REMAIN
VERY LIMITED.

CARIBBEAN SEA...
TWO FRONTS EXTEND INTO THE NW CARIB. THE LEADING BOUNDARY
IS WEAKENING FROM ERN CUBA TO HONDURAS AND THE SECOND
REINFORCING BOUNDARY EXTENDS FROM CENTRAL CUBA TO BELIZE. IT IS
IMPRESSIVELY COOL/DRY FOR THIS TIME OF YEAR BEHIND THE SECOND
BOUNDARY...TEMPS MAINLY IN THE 70'S F AND DEWPOINTS IN THE 50'S
F. BOTH OF THESE BOUNDARIES ARE DRY IN NATURE WITH ONLY
SCATTERED CLOUDS ALONG THEM. HOWEVER...THICK LOW CLOUDS AND
SHOWERS ARE BANKING UP ALONG THE COAST OF HONDURAS AND UPSLOPE
THE HIGH TERRAIN. THE SECOND BOUNDARY WILL LIKELY MERGE WITH THE
LEADING ONE LATER TONIGHT OR EARLY TOMORROW. A WEAK LOW-LEVEL
TROUGH...OR AT LEAST ITS ASSOCIATED MOISTURE...HAS SPLIT. THE
SRN EXTENSION IS CONTINUING W ALONG 79W S OF 15N AND THE NRN
PORTION IS OVER HISPANIOLA SWEPT UP BY THE LEADING FRONT.
SCATTERED SHOWERS ARE WITHIN 90 NM EITHER SIDE OF THE SRN
PORTION AND N OF 18N BETWEEN 70W-75W. ALOFT...A WEAK UPPER HIGH
IS SITUATED OVER SRN NICARAGUA WHILE TROUGHING LIES OVER THE ERN
CARIB INDUCED BY AN UPPER LOW NEAR 21N57W. THIS PATTERN IS
CREATING A MODESTLY DRY ENVIRONMENT ESPECIALLY OVER THE SW
WATERS.

ATLANTIC OCEAN...
AN ELONGATED AMPLIFIED UPPER TROUGH LIES JUST OFF THE E COAST OF
THE U.S. SUPPORTING A COMPLEX SFC LOW PRES SYSTEM OVER THE W
ATLC. A NEWLY FORMED SFC LOW IS IN OUR DISCUSSION ZONE ANALYZED
1010 MB NEAR 30N77W. THE TIGHT PRES GRADIENT BETWEEN THE LOW AND
HIGH PRES OVER THE SRN U.S. IS PRODUCING NLY WINDS TO GALE FORCE
WITHIN 180 NM W OF THE LOW. THE SAME UPPER SYSTEM IS ALSO
PROVIDING SUPPORT FOR TWO FRONTAL BOUNDARIES. THE LEADING ONE IS
SLOWING IN FORWARD SPEED FROM JUST E OF BERMUDA TO THE SE
BAHAMAS. THE SECOND BOUNDARY EXTENDS FROM 32N68W THRU THE
CENTRAL BAHAMAS TO CENTRAL CUBA. SCATTERED SHOWERS AND ISOLATED
TSTMS ARE WITHIN 60 NM E OF THE LEADING FRONT N OF 25N.
SCATTERED SHOWERS AND TSTMS ARE N OF 29N BETWEEN 76W-80W
ASSOCIATED WITH THE LOW. THIS LOW IS EXPECTED TO TRACK N OF THE
AREA...ALLOWING THE GALE CONDITIONS TO END IN ABOUT 18 HOURS.

THE REMAINDER OF THE ATLC BASIN IS RATHER TRANQUIL THANKS TO A
SPRAWLING DEEP LAYER HIGH PRES SYSTEM CENTERED NEAR 30N41W. THE
SFC CENTER...ANALYZED 1028 MB...IS PRODUCING N TO NE 20-25 KT
WINDS NEAR THE COAST OF AFRICA N OF 17N AND MAINLY 15-20 KT
WINDS ACROSS THE REMAINDER OF THE TROPICS. AN UPPER LOW IS
SPINNING NEAR 21N57W...BUT PRODUCING LITTLE WEATHER AT THE
MOMENT. A RETREATING UPPER TROUGH EXTENDS FROM MOROCCO TO 21N23W
THEN WWD TO 21N39W. STRONG WLY UPPER FLOW BETWEEN THIS TROUGH
AND A FLAT UPPER RIDGE OVER THE TROPICS IS SPREADING A PLUME OF
HIGH LEVEL CLOUDINESS S OF 15N.

$$
CANGIALOSI




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