[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 132335
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU OCT 13 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM
THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON
SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE JUST W OF THE CAPE VERDE ISLANDS
ALONG 28W S OF 17N MOVING W 15 KT. THE CIRCULATION ASSOCIATED
WITH THIS WAVE IS BECOMING INCREASINGLY WELL-DEFINED AND THE
CONVECTIVE STRUCTURE SHOWS SOME BANDING ESPECIALLY TO THE E OF
THE AXIS. MODEL TRENDS...PARTICULARLY FROM THE GFS...INDICATE
THAT LOW PRES MAY BE DEVELOPING ALONG THE WAVE AND THIS SEEMS
REASONABLE GIVEN THE CURRENT STRUCTURE. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION FROM 5N-15N BETWEEN 25W-32W.
SCATTERED MODERATE IS ALSO OVER THE CAPE VERDE ISLANDS FROM
14N-17N BETWEEN 22W-26W.

CENTRAL ATLANTIC TROPICAL WAVE TILTED ALONG 7N35W 19N38W MOVING
W 10-15 KT. THE WAVE CONTINUES TO LIE ALONG THE LEADING EDGE OF
A SURGE OF SAHARAN DUST...AND THE STRONG TILTED STRUCTURE NOTED
IN SATELLITE IMAGERY SUGGEST THAT THE WAVE MAY BE BECOMING
INCORPORATED INTO THE CIRCULATION OF THE WAVE TO THE E. DEEP
CONVECTION IS PRIMARILY ALONG AND S OF THE ITCZ.

TROPICAL WAVE LOCATED ABOUT 425 NM E OF THE LESSER ANTILLES
ALONG 7N54W 20N52W MOVING W 10 KT. THE WAVE HAS BEEN TRUDGING
THROUGH AN ENVIRONMENT OF MID/UPPER LEVEL WESTERLIES DUE TO AN
UPPER LOW NEAR 16N52W WHICH HAS ESSENTIALLY SLOWED ITS FORWARD
MOTION. ISOLATED SHOWERS/TSTMS FROM 12N-16N BETWEEN 53W-57W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N10W 13N25W 8N36W 15N46W. SCATTERED
MODERATE CONVECTION WITHIN 300 NM S OF THE AXIS...PARTLY DUE TO
TROPICAL WAVES...BETWEEN 25W-42W.

...DISCUSSION...

GULF OF MEXICO...
STRONG MID/UPPER LEVEL RIDGING IS PLANTED OVER THE AREA ANCHORED
BY AN UPPER HIGH OVER THE E GULF NEAR 25N85W AND RIDGE AXIS
STRETCHING FROM MEXICO CITY TO S/CENTRAL FLORIDA. THIS PATTERN
IS CREATING MOSTLY FAIR CONDITIONS OVER THE GULF WITH SCATTERED
CLOUDS AND AN OCCASIONAL SHOWER OR TSTM...ESPECIALLY OFF THE N
COAST OF THE YUCATAN PENINSULA. A COLD/STATIONARY FRONT HAS MADE
ITS WAY ACROSS THE RIO GRANDE INTO EXTREME NORTHERN MEXICO FROM
BETWEEN LAREDO AND DEL RIO TEXAS WNW TO NEAR NUEVO CASAS GRANDES
(NW OF CHIHUAHUA). TEMPERATURES ARE FALLING INTO THE 50S AND 60S
F BEHIND THE FRONT WITH LOW CLOUDS/RAIN COVERING MOST OF SW
TEXAS AND JUST OVER THE BORDER INTO MEXICO. SCATTERED TSTMS ARE
DEVELOPING ALONG THE FRONT N OF 27N BETWEEN 100W-107W. FARTHER
E...A WEAK 1009 MB LOW SITS JUST OFF THE COAST FROM DAYTONA
FLORIDA WITH A TROUGH RUNNING SW TO LAKE OKEECHOBEE. SCATTERED
LOW CLOUDS AND SHOWERS EXTEND N OF THIS TROUGH OVER N/CENTRAL
FLORIDA INTO SRN GEORGIA. THIS APPEARS TO BE THE INCIPIENT
STAGES OF A SWD PUSH OF DRY AIR...WHICH MAY MAKE IT TO THE SRN
GULF BY LATE IN THE WEEKEND.

CARIBBEAN...
THE STAGNANT PATTERN OVER THE CARIBBEAN IS STILL AFFECTING THE
ISLANDS OF HISPANIOLA AND PUERTO RICO AND THE OFFSHORE WATERS
WITH BOUTS OF VERY HEAVY RAIN. THE CURRENT SET-UP HIGHLIGHTS AN
ELONGATED SURFACE TROUGH STRETCHING FROM THE GULF OF HONDURAS TO
JAMAICA AND THE WINDWARD PASSAGE...AND DEEP TROPICAL MOISTURE SE
OF THIS AXIS IS PRODUCING SCATTERED SHOWERS/TSTMS WITH EMBEDDED
POCKETS OF HEAVIER CONVECTION FROM NICARAGUA/COSTA RICA NEWD TO
HISPANIOLA AND PUERTO RICO. THE STRONGEST CONVECTION CURRENTLY
EXTENDS ALONG A LINE FROM WRN PUERTO RICO AND THE MONA PASSAGE
SW TO NEAR ARUBA. SEVERAL WEAK LOWS HAVE BEEN DEVELOPING ALONG
THE SURFACE TROUGH AND THIS HAS FOCUSED ADDITIONAL TSTM
DEVELOPMENT OVER HAITI...JAMAICA...COASTAL HONDURAS...AND
BELIZE. THERE IS NO IMMEDIATE END IN SIGHT FOR THE WET WEATHER
WITH THE MOISTURE PLUME EXPECTED TO REMAIN ENTRENCHED FROM THE
SW CARIBBEAN TO HISPANIOLA AT LEAST THROUGH THE MIDDLE OF NEXT
WEEK. HOWEVER...THERE DOES SEEM TO BE THE POSSIBILITY OF
SLIGHTLY DRIER AIR WORKING ITS WAY IN FROM THE E WHICH COULD
DECREASE THE RAIN CHANCES FOR AREAS LIKE PUERTO RICO AND THE
VIRGIN ISLANDS BY MON OR TUE. ELSEWHERE...DRY AIR AND LITTLE TO
NO CONVECTION ARE IN CONTROL OVER THE NW AND FAR E CARIBBEAN.
SCATTERED TSTMS HAVE FORMED OVER THE YUCATAN PENINSULA ALONG THE
SEA BREEZE AND ISOLATED SHOWERS ARE MOVING ACROSS THE WINDWARD
ISLANDS... OTHERWISE THOSE AREAS ARE ENJOYING A FINE EVENING.

WEST ATLANTIC...
THE CARIBBEAN SURFACE TROUGH CONTINUES NE OUT OF THE WINDWARD
PASSAGE TO A 1004 MB LOW NEAR 23N69W THEN TO A SECOND 1004 MB
LOW NEAR 30N61W. THE SURFACE TROUGH IS COLLOCATED WITH AN UPPER
TROUGH WITH TWO UPPER LOWS LOCATED NEAR 33N66W AND 23N71W.
WIDELY SCATTERED MODERATE CONVECTION EXTENDS UP TO 300/350 NM SE
OF THE SURFACE TROUGH WHILE MUCH DRIER AIR FILTERS IN FROM THE
W...HAVING SPREAD OVER MUCH OF FLORIDA AND THE BAHAMAS.

EAST/CENTRAL ATLANTIC...
A LARGE AND TUMBLING MID/UPPER LOW IS LOCATED ABOUT 500 NM E OF
THE LEEWARD ISLANDS NEAR 16N53W AND IS MOVING QUICKLY W AT ABOUT
15 KT. A LARGE AREA OF DRY AIR AHEAD OF THE LOW IS BEING PULLED
SWD ACROSS THE LESSER ANTILLES...AND ONLY A SMALL AMOUNT OF
MOISTURE IS BEING PULLED NWD ON THE E SIDE OF THE LOW.
HENCE...THERE IS VERY LITTLE IN THE WAY OF CONVECTIVE ACTIVITY W
OF 40W EXCEPT FOR NORMAL TRADE WIND SHOWERS. A SHORTWAVE TROUGH
IS SWINGING ACROSS THE SUBTROPICS FROM 30N27W 23N34W 23N43W AND
HAS INDUCED THE DEVELOPMENT OF A SURFACE TROUGH FROM 18N48W TO
25N37W WITH A WEAK 1014 MB LOW NEAR 22N42W. INTERMITTENT
SHOWERS/TSTMS HAVE BEEN POPPING NEAR THE LOW/TROUGH BUT IT IS
LARGELY INSIGNIFICANT. THE MOST WIDESPREAD CONVECTION IS LOCATED
WITHIN THE TROPICS E OF 40W DUE TO TWO TROPICAL WAVES AND AN
UPPER LEVEL ANTICYCLONE CENTERED NEAR 11N27W.

$$
BERG


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