[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 291744
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU OCT 29 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 30W/31W S OF 19N WITH A 1014 MB LOW ALONG
THE WAVE NEAR 15N MOVING W NEAR 10 KT. SATELLITE IMAGERY CLEARLY
SHOWS THE LOW LEVEL CIRCULATION ALONG THE WAVE AXIS WITH THE
WAVE AXIS AT THE PEAK OF A MOISTURE MAXIMUM AS INDICATED BY THE
TOTAL PRECIPITABLE WATER IMAGERY. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE FROM 14N-20N BETWEEN
30W-33W.

TROPICAL WAVE IS ALONG 57W S OF 16N MOVING W 10-15 KT. ANY LOW
LEVEL SIGNATURE IS OBSCURED BY CIRRUS CLOUDS AS WAVE IS LOCATED
BENEATH AN UPPER RIDGE. ANY CONVECTION IS S OF THE ITCZ AXIS.

TROPICAL WAVE IS ALONG 69W/70W S OF 17N MOVING W 10-15 KT.
CARIBBEAN IS DOMINATED BY DEEP LAYERED MOISTURE OF WHICH THE
WAVE IS EMBEDDED WITH POSITION BASED ON PERSISTENCE. EVEN WITH
DEEP MOISTURE THERE IS NO ASSOCIATED SHOWERS/CONVECTION.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N12W 6N21W 10N46W 10N62W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
WITHIN 120 NM OF THE ITCZ FROM 17W-27W AND FROM 32W-43W AND S OF
THE ITCZ AXIS W OF 50W TO INLAND OVER SOUTH AMERICA.

...DISCUSSION...

GULF OF MEXICO...
THE QUASI-STATIONARY FRONT REMAINS ACROSS THE N GULF FROM THE W
ATLC OVER THE FLORIDA PANHANDLE FROM JACKSONVILLE TO PANAMA CITY
CONTINUING W OVER SE LOUISIANA NEAR NEW ORLEANS AS A WARM FRONT.
MOST OF THE UPPER LEVEL SUPPORT FOR THIS FRONT HAS MOVED E INTO
THE W/CENTRAL ATLC AND THE LINGERING FRONT IS GENERATING A FEW
ISOLATED SHOWERS OVER THE NW GULF N OF 24N W OF 93W. BROAD UPPER
RIDGE DOMINATES THE GULF ANCHORED NEAR 25N86W. STRONG SE TO E
SURFACE WINDS ARE ACROSS THE CENTRAL AND W GULF WHICH WILL SHIFT
AROUND TO THE N BEHIND A FRONT THAT IS EXPECTED TO ENTER THE
GULF LATE TONIGHT/EARLY FRI. A SURFACE RIDGE COVERS THE FAR E
GULF INTO THE W ATLC AND WILL SHIFT E WITH THE APPROACHING FRONT
EXPECTED ON FRI. STRONG SUBSIDENCE AND DRY STABLE AIR COVER THE
E GULF...THUS CLEAR SKIES OVER MOST OF THE GULF THIS AFTERNOON.

CARIBBEAN SEA...
BROAD UPPER LOW COVERS THE W CARIBBEAN CENTERED NEAR 14N80W AND
COUPLED WITH THE ITCZ AXIS THAT EXTENDS FROM OVER COLOMBIA TO
COSTA RICA INTO THE E PACIFIC REGION ARE GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS S OF 16N BETWEEN 74W-84W. AN
UPPER RIDGE EXTENDS FROM THE TROPICAL ATLC W ALONG THE N COAST
OF SOUTH AMERICA PRODUCING SCATTERED CIRRUS CLOUDS ACROSS THE E
CARIBBEAN. THE HIGH PRESSURE OVER THE ATLC AND LOWER PRESSURE
OVER SOUTH AMERICA IS GENERATING MODERATE EASTERLY TRADE WINDS
ACROSS THE CARIBBEAN USHERING IN SOME ISOLATED FAST MOVING
SHOWERS.

ATLANTIC OCEAN...
A DEEP LAYERED TROUGH IS DIGGING S OVER THE W/CENTRAL ATLC N OF
28N W OF 50W SUPPORTING A COLD FRONT THAT ENTERS THE REGION NEAR
BERMUDA ALONG 31N70W TO 30N77W BECOMING QUASI-STATIONARY ACROSS
NE FLORIDA INTO THE GULF OF MEXICO NEAR JACKSONVILLE FLORIDA.
THIS UPPER TROUGH IS BRINGING IN DRIER AIR AND STRONG SUBSIDENCE
N OF 30N FROM 59W-73W THUS NO SHOWERS ARE ASSOCIATED WITH THE
FRONT. A SURFACE RIDGE COVERS THE W ATLC ACROSS FLORIDA INTO THE
GULF OF MEXICO ANCHORED BY A 1020 MB HIGH NEAR 27N72W AND IS
BRIDGING THE FRONTAL BOUNDARY ABOVE. A VERY LARGE UPPER LOW IS
WELL N OF THE REGION OVER THE FAR NE ATLC SUPPORTING A
STATIONARY BOUNDARY ENTERING THE E ATLC NEAR 23N28W EXTENDING SW
TO 27N42W. THE MOISTURE AND THUS ANY SHOWER ACTIVITY IS N OF THE
REGION. IN THE TROPICS...AN UPPER RIDGE EXTENDS NEAR 4N35W NW
ALONG 10N54W THEN ALONG THE N COAST OF SOUTH AMERICA GIVING MOST
OF THE TROPICS BROKEN TO OVERCAST CIRRUS CLOUDS.

$$
WALLACE





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