[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111754
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE OCT 11 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

E ATLC TROPICAL WAVE IS ALONG 27W S OF 17N MOVING W 10-15 KT.  A
BROAD ROTATION IS NOTED WITHIN THE LOW CLOUDS WHICH HAS GOOD
CONTINUITY FROM YESTERDAY.  ISOLATED MODERATE CONVECTION FROM
10N-14N BETWEEN 25W-28W.  A SURGE IN ELY WINDS IS BEHIND THE
WAVE PRODUCING WIDELY SCATTERED MODERATE FROM 5N-14N BETWEEN
20W-25W.

CENTRAL ATLC TROPICAL WAVE IS ALONG 39W/40W S OF 18N MOVING W 15
KT.  THERE IS A LARGE AREA OF CYCLONIC TURNING NEAR THE WAVE
AXIS WITH SW SHEAR ENHANCING ISOLATED MODERATE CONVECTION FROM
15N-20N BETWEEN 36W-40W.  A MESOSCALE-CONVECTIVE-VORTEX (MCV) IS
LOCATED BEHIND THE WAVE NEAR 10.5N35.5W.  LOW-LEVEL WIND DATA
SUGGEST THE WAVE IS FARTHER W ... DISPLACED DUE TO WLY SHEAR.

CENTRAL ATLC TROPICAL WAVE IS ALONG 49W S OF 14N MOVING W 10-15
KT. THIS REMAINS A LOW AMPLITUDE WAVE WITH ONLY A FEW ITCZ TSTMS
NEAR THE AXIS WITHIN 60 NM OF 10N49W.

TROPICAL WAVE ALONG THE LESSER ANTILLES NEAR 61W S OF 20N MOVING
W 10 KT.  THE LOW ALONG THE WAVE APPEARS TO HAVE DISSIPATED.
COMPUTER MODELS SUGGEST A SMALL ENHANCEMENT IN SHOWERS/TSTMS IN
THE E CARIBBEAN TODAY.  THE WAVE IS EXPECTED TO WEAKEN
SIGNIFICANTLY AS IT INTERACTS WITH THE LOW/MID LEVEL WLY FLOW IN
THE E-CENTRAL CARIBBEAN.  SCATTERED MODERATE CONVECTION IS N OF
BARBADOS TO 20N BETWEEN 59W-61W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 12N16W 11N30W 13N38W 10N48W 12N58W.
WIDELY SCATTERED MODERATE FROM 4N-14N BETWEEN 22W-33W.


...DISCUSSION...

GULF OF MEXICO...
MID/UPPER HIGH IS ANCHORED NEAR 26.5N85W IN THE E GULF WITH DRY
AIR ALOFT CONTROLLING THE REGION.  THE ONLY PLACE TO OVERCOME
THE DRYNESS IS IN THE WESTERN GULF ALONG THE COAST OF MEXICO.
PLENTIFUL LOW-LEVEL MOISTURE AND SOME LIFT FROM AN UPPER TROUGH
EXTENDING FROM THE LOW IN COLORADO WITH SOUTHWARD TO CENTRAL
MEXICO.  ISOLATED TSTMS ARE WITHIN 75 NM OF THE COAST OF MEXICO
BETWEEN 22.5N-25.5N.  MOST OF THE GULF HAS CLEAR TO PARTLY
CLOUDY SKIES SAVE NEAR THE COASTS OF TEXAS AND SE MEXICO.
SPORADIC RAIN/TSTM AREAS ARE POSSIBLE FROM S TEXAS TO NE MEXICO
OVER THE NEXT COUPLE OF DAYS WITH A NEARLY STATIONARY PATTERN IN
PLACE.  IN ADDITION A WEAK COLD FRONT WILL BE PUSHING INTO
EXTREME S TEXAS OVERNIGHT AND COULD FURTHER INCREASE THE
INSTABILITY.  OTHERWISE...WEAK SURFACE RIDGING IS OVER THE GULF
OF MEXICO WITH THE AXIS ALONG 89W/90W FROM THE COAST OF SE
LOUISIANA TO YUCATAN.   ANY COLD FRONTS TO ENTER THE REGION
DURING THE NEXT 5 DAYS OR SO WILL LIKELY BE WEAK.

CARIBBEAN SEA AND W ATLANTIC W OF 58W...
NO BIG CHANGES FROM YESTERDAY AS AN ANOMALOUS PATTERN REMAINS
WITH STRONG W TO WSW FLOW IN THE MID/UPPER LEVELS CONTROLLING
THE AREA S OF A TROUGH AXIS FROM THE WINDWARD PASSAGE TO NE
HONDURAS.  VERY HIGH MOISTURE LEVELS AND UPPER DIFFLUENCE IS
CONTINUING TO PRODUCE A LARGE AREA OF UNSETTLED WEATHER OVER THE
CARIBBEAN SE OF THE TROUGH.  1005 MB LOW IS JUST S OF SE CUBA
WITH ANOTHER WEAK 1006 MB LOW JUST OFFSHORE OF NE HONDURAS.
SCATTERED SHOWERS/TSTM COVER THE REGION N OF S AMERICA BETWEEN
70W-81W.  MORE ISOLATED ACTIVITY IS WITHIN 75 NM OF THE COAST OF
HONDURAS E OF 87.5W.  A WEAK UPPER HIGH HAS FORMED NEAR 16N75W
PROVIDING PLENTY OF UPPER DIFFLUENCE FOR NEARBY SHOWERS/TSTMS.
FARTHER E... COMPLEX MID/UPPER LOW HAS A MEAN CENTER NEAR 26N71W
WITH A 1005 MB S OF THE LOW N OF PUERTO RICO NEAR 22N68.5W.
VERY HEAVY RAINFALL HAS BEEN BLANKETING THE ISLAND AND THE
ADJACENT ISLANDS APPROACHING ST. MARTIN.  OVERALL SCATTERED
MODERATE CONVECTION COVERS THE AREA FROM 63W-70W BETWEEN 15N-20N.
HEAVY RAIN... FLASH FLOODING AND THE POTENTIAL FOR LIFE-
THREATENING MUDSLIDES EXISTS IN THE NE CARIBBEAN WITH THIS
WEATHER SYSTEM ESPECIALLY IN HIGHER TERRAIN.   TROPICAL MOISTURE
IS EXPECTED TO REMAIN OVER MOST OF THE CARIBBEAN THROUGH MID
WEEK WITH AN ENHANCED CHANCE OF FLOODING... AND SOME DRYING OVER
THE NW CARIBBEAN INCLUDING YUCATAN AND W & CENTRAL CUBA.  THINGS
COULD GET A LITTLE DRIER IN PUERTO RICO IN A COUPLE DAYS AS THE
LARGE LOW PRESSURE AREA HEADS NORTHWARD IN THE GENERAL DIRECTION
OF BERMUDA.  UNFORTUNATELY THIS COULD PUT THE FLOODING-PRONE
ISLAND OF HISPANIOLA AT RISK FOR CONTINUED HEAVY RAINFALL
THROUGHOUT THE WEEK.  OTHERWISE OVER W ATLC WATERS THE UPPER
TROUGH IS PRODUCING SCATTERED SHOWERS/TSTMS FROM 20N-31N BETWEEN
59W-68W.  MODELS SUGGEST THAT SOME TYPE OF SUBTROPICAL LOW COULD
TRY TO FORM IN A FEW DAYS IN THE VICINITY OF BERMUDA THAT THERE
IS A LOT OF UNCERTAINTY ON IF IT WILL EVEN HAVE MANY
SUBTROPICAL LOW CHARACTERISTICS.

REST OF THE ATLANTIC...
MID/UPPER HIGH LIES NEAR 28N47W... PROVIDING FAIR WEATHER TO THE
SUBTROPICAL CENTRAL ATLC W OF 35W. IN THE REMAINDER OF THE
SUBTROPICAL ATLC A BROAD UPPER TROUGH COVERS THE REGION WITH THE
AXIS EXTENDING FROM THE CANARY ISLANDS THROUGH 22W35W INTO A
DEVELOPING MID/UPPER LOW NEAR 20N47W.  WEAK 1020 MB HIGH IS OVER
THE NE ATLC NEAR 26N24W WITH A STRONGER 1023 MB HIGH NEAR 35N53W
INCREASING THE TRADES A BIT W OF 40W.  UPPER RIDGING HAS BEEN
PUSHED SOUTHWARD RECENTLY AND NOW LIES FROM NEAR SW AFRICA NEAR
8N12W TO 6N43W.  NET WLY SHEAR IS ACROSS THE ITCZ WITH PLENTY OF
DIFFLUENCE TO AID SHOWER/TSTM DEVELOPMENT.  THE GFS HINTS THAT
UPPER RIDGING WILL TRY TO GROW NORTHWARD AGAIN AS THE DEVELOPING
MID/UPPER LOW HEADS WESTWARD WITH LESS SHEAR...THOUGH IT IS
GETTING LATE TO SEE ANY WAVES TRY TO DEVELOP IN THE TROPICAL
ATLC.

$$
BLAKE

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