[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 061108
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT OCT 06 2007

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1030 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS IN THE CENTRAL ATLANTIC ALONG 50W S OF 19N
MOVING W 10 KT OVER THE PAST 24 HOURS. A 1009 MB LOW IS ALONG
THE WAVE AXIS NEAR 14N. THE INTERACTION BETWEEN THIS WAVE AND
DIFFLUENCE ALOFT TO THE E OF AN UPPER TROUGH HAS CAUSED
CONVECTION TO FLARE UP ALONG AND TO THE E OF THE WAVE/LOW FROM
13N-16N BETWEEN 47W-50W. HOWEVER...SIGNIFICANT DEVELOPMENT IS
UNLIKELY DUE TO UNFAVORABLE UPPER WINDS.

...THE ITCZ...
AXIS CENTERED ALONG 10N14W 7N26W 8N37W 9N48W 11N62W. BESIDES FOR
THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE...ISOLATED
MODERATE IS WITHIN 120 NM N AND 90 NM S OF THE AXIS BETWEEN
31W-38W.

DISCUSSION...

THE GULF OF MEXICO...
THE AREA OF LOW PRES THAT WE HAVE BEEN TRACKING FOR SEVERAL DAYS
HAS NOW MOVED INLAND OVER SE TEXAS. ASSOCIATED SHOWER AND TSTM
ACTIVITY IS MINIMAL WITH DOPPLER RADAR ONLY DEPICTING A FEW
SHOWERS AND TSTMS IN VERY CLOSE TO THE CENTER. THE MORE
WIDESPREAD SHOWER ACTIVITY IS OVER FLORIDA AND THE EXTREME SE
GULF. DOPPLER RADAR IN THIS AREA IS SHOWING STREAMS OF SCATTERED
SHOWERS AND TSTMS PUSHING IN FROM THE ATLC WATERS S OF 30N E OF
85W. THIS ACTIVITY IS TRIGGERED BY STRONG MOIST LOW-LEVEL
FLOW AND SOME CONVERGENCE NEAR THE CREST OF A W CARIB TROUGH. IN
ADDITION...WATER VAPOR IMAGERY SHOWS A WEAK DISTURBANCE OVER THE
STATE WHICH IS ADDING INSTABILITY. THE REMAINDER OF THE REGION
IS FAIRLY QUIET UNDER THE INFLUENCE OF UPPER RIDGING RUNNING N-S
ALONG 92W WITH LARGE SCALE STABLE SINKING AIR. A MID TO UPPER
LEVEL LOW LIES ABOVE CENTRAL MEXICO GENERATING CLOUDINESS AND
SHOWERS OVER PORTIONS OF MEXICO AND THE TROPICAL EPAC.

THE CARIBBEAN SEA...
COMPLEX ELONGATED LOW-LEVEL TROUGHING EXISTS ACROSS THE
CARIBBEAN THIS MORNING. ONE TROUGH IS IN THE W PORTION EXTENDING
FROM THE STRAITS OF FLORIDA TO 12N77W. SFC OBSERVATIONS AT 09Z
SHOW A BROAD AREA OF FAIRLY LOW PRES WITH AN ESTIMATED 1006 MB
LOW CENTERED ALONG THE AXIS NEAR 17N81W. A 0312 Z ASCAT PASS
SHOWED GOOD TURNING IN THE NW CARIB BUT REVEALED THAT THE WINDS
ARE CURRENTLY VERY LIGHT. AN INFRARED ANIMATION SHOWS SOME
INCREASE IN CONVECTION OVERNIGHT BUT THE ACTIVITY STILL REMAINS
DISORGANIZED FROM 19N-22N BETWEEN 78W-83W AND WITHIN 60 NM OF
17N84W. SOME SLOW DEVELOPMENT IS POSSIBLE OVER THE NEXT FEW DAYS
AS THE LOW DRIFTS TO THE W OR SW. ANOTHER LOW-LEVEL TROUGH IS
LOCATED OVER THE GREATER ANTILLES EXTENDING FROM ERN CUBA ACROSS
HISPANIOLA AND THEN NEWARD N OF THE LEEWARD ISLANDS. THE
INTERACTION WITH AN UPPER LOW IS PRODUCING A SWATH OF SHOWERS
AND TSTMS N OF THE AREA...MORE ON THIS FEATURE IN THE ATLANTIC
DISCUSSION BELOW. ELSEWHERE IN THE MID AND UPPER
LEVELS...RIDGING DOMINATES MUCH OF THE BASIN EXTENDING SE FROM
THE CENTRAL GOMEX. THE UPPER FLOW IS LIGHTER IN THE ERN CARIB
DUE TO THE AFOREMENTIONED UPPER LOW LOCATED N OF THE DOMINICAN
REPUBLIC. THIS OVERALL PATTERN IS PRODUCING A LOT OF CLOUDINESS
ACROSS THE REGION. HOWEVER...DEEP MOISTURE IS CONFINED TO NEAR
THE LOW-LEVEL BOUNDARIES AND IN THE S CENTRAL CARIB S OF 16N
BETWEEN 69W-72W.

THE TRADE WIND FLOW IS SIGNIFICANTLY INTERRUPTED ACROSS THE
CARIB DUE TO THE PRESCIENCE OF THE SFC BOUNDARIES. THESE MAINLY
LIGHT AND CHANGEABLE WINDS ARE EXPECTED TO PERSIST ACROSS THE
BULK OF THE AREA OVER THE NEXT DAY OR SO.

THE ATLANTIC OCEAN...
AN ELONGATED SFC TROUGH ANALYZED FROM 22N63W TO ERN CUBA
DOMINATES THE SW PORTION OF THE ATLC BASIN. THERE ARE A FEW
EMBEDDED VORT MAXES ALONG THIS STRETCHED OUT TROUGH AXIS.
HOWEVER...THE MAIN ENERGY APPEARS TO BE NEAR THE UPPER LOW
LOCATED JUST N OF THE DOMINICAN REPUBLIC. THIS INTERACTION IS
PRODUCING SCATTERED SHOWERS AND TSTMS S OF 24N BETWEEN 62W-72W.
PRECIP APPEARS MOST CONCENTRATED JUST N OF THE LEEWARD ISLANDS
FROM 19N-21N BETWEEN 63W-65W. ENVIRONMENTAL CONDITIONS ARE
GENERALLY FAVORABLE FOR SOME DEVELOPMENT OVER THE NEXT COUPLE OF
DAYS AS IT MOVES SLOWLY NORTHWARD. THE TIGHTENED PRES GRADIENT
BETWEEN THIS E-W TROUGHING AND HEALTHY RIDGING OFF THE
MID-ATLANTIC COASTLINE IS PRODUCING MODERATE TO STRONG ELY WINDS
AND STEEP WIND WAVES/SWELL N OF 25N W OF 50W.

IN THE CENTRAL ATLC...A PIECE OF AN OLD FRONTAL ZONE THAT
ABSORBED THE REMNANTS OF MELISSA IS ANALYZED ALONG 29N42W
23N56W. THE COMBINATION OF LOW-LEVEL CONVERGENCE NEAR THIS
BOUNDARY...A TROPICAL WAVE TO ITS S ALONG 50W AND INSTABILITY
ALOFT NEAR A TROUGH ALONG 51W/52W IS PRODUCING SCATTERED
MODERATE CONVECTION FROM 18N-25N BETWEEN 45W-54W. STRONG UPPER
WLY WINDS E OF THE TROUGH IS SPREADING DEBRIS MOISTURE INTO THE
E ATLC N OF 25N W OF 25W. THE REMAINDER OF THE E ATLC IS MUCH
QUIETER...WITH STABLE CONDITIONS UNDER THE INFLUENCE OF UPPER
RIDGING AND A 1019 MB SFC HIGH NEAR 25N29W.

$$
CANGIALOSI




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