[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 301716
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST MON OCT 30 2006

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...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1700 UTC.

...TROPICAL WAVES...

A LOW AMPLITUDE TROPICAL WAVE IS ALONG 59W S OF 13N MOVING W
NEAR 10-15 KT OVER THE PAST 24 HOURS. THIS WAVE IS NOT
RECOGNIZABLE IN SATELLITE IMAGES OR IN ANY OF THE AVAILABLE
DATA. THE WAVE MAY BE PUSHED FURTHER W IN THE 18Z MAP TO ACCOUNT
FOR THE SWIFT STEERING FLOW ON THE S PERIPHERY OF A
LOW/MID-LEVEL RIDGE.

A TROPICAL WAVE IS ALONG 77W/78W S OF 21N MOVING W NEAR 15 KT.
THIS WAVE HAS BECOME MUCH LESS DISTINCT THAN IT WAS YESTERDAY AS
IT IS INTERACTING WITH A FRONTAL SYSTEM TO ITS N. THIS TROPICAL
WAVE HAS LIKELY SPLIT OR WILL SOON DO SO WITH THE NRN PORTION
GETTING PULLED NW WHILE THE SRN PORTION CONTINUES W. A FEW MID
LEVEL SWIRLS ARE EVIDENT ABOUT THE WAVE AXIS. THE INTERACTING
WITH THE FRONT AND UPPER LEVEL JET IS PRODUCING LOTS OF MOISTURE
IN THE CARIBBEAN...BUT SHOWERS AND TSTMS LIKELY CONTRIBUTED
MORE DIRECTLY WITH THE WAVE IS WITHIN 180 NM E OF THE AXIS.

A TROPICAL WAVE IS IN THE WRN CARIBBEAN ALONG 84W S OF 21N
MOVING W 10 TO 15 KT. A BROAD AREA OF MAINLY MID-LEVEL TURNING
IS SEEN ON VIS AND IR IMAGERY ABOUT THE WAVE AXIS. SCATTERED
SHOWERS AND TSTMS HAVE INCREASED IN INTENSITY OVER THE PAST FEW
HOURS BUT REMAIN DISORGANIZED WITHIN 180 NM EITHER SIDE OF THE
WAVE AXIS. THIS ACTIVITY IS BEING ENHANCED BY THE UPPER LEVEL
JET TO ITS W.

FOR MORE INFO ON THE TROPICAL WAVES REFER TO THE CARIBBEAN IN
THE DISCUSSION SECTION BELOW.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N13W 8N30W 7N41W 6N58W. SCATTERED
MODERATE CONVECTION IS FROM 4N-14N BETWEEN 18W-26W. SCATTERED
MODERATE IS ALSO WITHIN 150 NM TO THE N OF THE AXIS BETWEEN
37W-49W.

...DISCUSSION...
THE GULF OF MEXICO...
A VERY DRY STABLE MID/UPPER LEVEL ENVIRONMENT IS IN PLACE ACROSS
THE GULF WITH COOL AIR STRATOCUMULUS CLOUDS STILL VISIBLE. A
SHARP MOISTURE GRAD EXISTS JUST SE OF THE AREA WHERE WIDESPREAD
MOISTURE LIES IN THE CARIBBEAN. THE DOMINATING SFC HIGH PRES
SYSTEM CONTINUES TO SLIDE EASTWARD...NOW CENTERED IN THE SE U.S.
THIS HAS ALLOWED LIGHT WINDS TO TURN E AND SELY EXCEPT FOR THE
FAR WRN GULF WHERE WINDS ARE A STRONGER 15-20 KT FROM THE S.
LOOKING AHEAD OVER THE NEXT FEW DAYS...SOME MOISTURE IN THE
CARIBBEAN MAY BACK INTO THE SE GULF PUSHED BY ELY FLOW. A WEAK
COLD FRONT MAY MOVE ACROSS THE NRN PORTION OF THE AREA BEFORE
BEING REPLACED BY ANOTHER SFC RIDGE WHICH WILL BUILD N OF THE
AREA BY MID-LATE WEEK.

THE CARIBBEAN SEA...
WIDESPREAD MOISTURE EXISTS IN THE CENTRAL AND WRN CARIBBEAN W OF
72W. THERE IS A SHARP MOISTURE GRAD...ASSOCIATED WITH A SWLY
UPPER LEVEL JET...BETWEEN THE WRN CARIBBEAN AND THE VERY DRY AIR
ALOFT IN THE GULF. DISORGANIZED SCATTERED SHOWERS AND TSTMS ARE
EMBEDDED IN THE LARGE MOISTURE PLUME AND ARE BEING ENHANCED BY
SEVERAL SFC FEATURES...A TROPICAL WAVE ALONG 77W AND ALONG 84W
AS WELL AS THE TAIL END OF A FRONTAL BOUNDARY JUST N OF THE
AREA. UPPER DIFFLUENCE AND LOW-LEVEL LIFT IS PRODUCED SCATTERED
SHOWERS AND TSTMS ACROSS THE CARIBBEAN W OF 72W.  THE STRONGEST
ACTIVITY IS NEAR THE TROPICAL WAVES...REFER TO THAT SECTION FOR
MORE DETAILS. THE UPPER LEVEL JET...WHICH IS LOCATED BETWEEN A
STRONG TROUGH IN THE ERN GULF AND OFF THE U.S. E COAST AND A
SPRAWLING UPPER HIGH CENTERED OVER HISPANIOLA...IS DRIVING SOME
OF THIS MOISTURE NEWARD INTO THE ATLC. THE ERN AND PART OF THE
CENTRAL CARIBBEAN IS QUIET WITH PLENTY OF DRY AIR ALOFT BEING
ADVECTED INTO THE AREA. THE ONLY AREA OF ANY SIGNIFICANT SHOWER
ACTIVITY IS IN THE EXTREME SE PORTION WHERE SCATTERED SHOWERS
AND TSTMS ARE SINKING SWD IN A UPPER DIFFLUENT ZONE ABOVE THE
ITCZ S OF 12N E OF 65W. TYPICAL SHALLOW TRADE WINDS SHOWERS ARE
STREAMING ACROSS THE ERN CARIB AS WELL AS SEEN ON SAN JUAN 88D.
OVER THE NEXT FEW DAYS...MODELS SUGGEST THAT THE LARGE AREA OF
MOISTURE WILL GET PUSHED W AND SHRINK IN SIZE AS DRY AIR ALOFT
CONTINUES TO BEING ADVECTED INTO THE ERN AND CNTRL CARIB.

THE ATLANTIC OCEAN...
AN 80-100 KT SWLY JET WHICH LIES BETWEEN A LARGE RIDGE IN THE
ATLC AND A STRONG TROUGH OFF THE U.S. E COAST IS ENHANCING AND
ADVECTING TROPICAL MOISTURE FROM THE WRN CARIB ACROSS THE
BAHAMAS INTO THE WRN ATLC WITHIN 500 NM E OF A LINE FROM THE
FLORIDA STRAITS TO 32N69W. AN ASSOCIATED FRONTAL BOUNDARY LIES
ALONG 32N56W 26N66W THEN STATIONARY TO THE CENTRAL BAHAMAS. THE
MOST ACTIVE WEATHER IS WITHIN 180 NM EITHER SIDE OF THE FRONT
FROM 23N-27N WHERE A SFC LOW MAY BE TRYING TO FORM AS IS
SUGGESTED BY GFS. A ELONGATED HIGH AMPLITUDE LARGE RIDGE LIES TO
THE E OF THE JET COVERING THE AREA W OF 40W N OF 20N. PLENTY OF
DRY AIR ALOFT IS ASSOCIATED WITH THIS RIDGE. A LARGE LOW PRES
SYSTEM COVERS MUCH OF THE NE PORTION OF THE DISCUSSION
AREA...WITH THE SFC LOW ANALYZED AT 1000 MB NEAR 32N28W. THIS
LOW IS COLD-CORE AT THE MOMENT WITH A COLD FRONT EXTENDING ALONG
32N25W 23N31W 21N46W. SCATTERED SHOWERS AND TSTMS ARE WITHIN 180
NM E OF THE FRONT N OF 25N AND WITHIN 240 NM OF THE SFC LOW. IN
THE DEEP TROPICS...A LARGE ELONGATED UPPER LOW IS CENTERED NEAR
14N44W WITH AN UPPER JET ORIGINATING AT THE BASE OF THE LOW
ALONG 10N45W 18N31W 23N16W. THIS STRONG SWLY FLOW IS SHEARING
MUCH OF THE CONVECTION IN THE ITCZ TO THE NE. ITCZ CONVECTION IS
BEING ENHANCED BY UPPER DIFFLUENT AIR BETWEEN 18W-26W. PLENTY OF
DRY AIR ALOFT LIES TO THE W OF THE TROPICAL JET.

$$
CANGIALOSI




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