[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 011030 CCA
TWDAT

TROPICAL WEATHER DISCUSSION...CORRECTED
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST MON DEC 01 2008

...CORRECTED FINAL POINT OF ITCZ AXIS...

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 11N14W 5N22W 5N33W 4N42W 1N50W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 3N-8N
BETWEEN 19W-23W. SCATTERED MODERATE CONVECTION IS FROM 3N-8N
BETWEEN 23W-34W. SCATTERED MODERATE CONVECTION IS ALSO FROM
5N-8N BETWEEN 40W-44W.

...DISCUSSION...

GULF OF MEXICO...
A VIGOROUS DEEP LAYER TROUGH OVER THE E CONUS EXTENDS INTO NE
MEXICO...WITH TWO ASSOCIATED SURFACE COLD FRONTS...ONE COLD
FRONT OVER THE E GULF AND THE OTHER COLD FRONT OVER THE NW GULF.
THE COLD FRONT OVER THE E GULF EXTENDS FROM NE FLORIDA NEAR
31N82W TO 26N84W TO THE YUCATAN PENINSULA NEAR 21N88W. THE
COMBINATION OF INSTABILITY AND STRONG DEEP LAYER WIND SHEAR
ALONG AND E OF THE FRONT IS GENERATING A LINE OF SHOWERS AND
THUNDERSTORMS EXTENDING FROM 31N77W TO 25N83W. THIS ACTIVITY IS
SUPPORTING A 1009 MB SURFACE HIGH W OF THE S FLORIDA PENINSULA
NEAR 26N82W. ADDITIONALLY...THIS ACTIVITY IS BEING ENHANCED BY
PARTICULARLY STRONG UPPER LEVEL DIVERGENCE IN THE SE QUADRANT OF
A 140-150 KT UPPER LEVEL JET MAXIMUM ORIENTED FROM
SOUTH-SOUTHWEST TO NORTH-NORTHEAST OVER THE SE CONUS. THE COLD
FRONT OVER THE NW GULF EXTENDS FROM S ALABAMA NEAR 30N87W TO
28N92W TO 26N97W...WITH STABLE ATMOSPHERIC CONDITIONS
SUPPRESSING DEEP CONVECTION IN THE VICINITY OF THIS FRONT.
ADDITIONALLY...BETWEEN THE TWO COLD FRONTS...A 1013 MB SURFACE
HIGH IS PRESENT OVER E MEXICO NEAR 24N98W...WHICH IS FURTHER
SUPPRESSING DEEP CONVECTION OVER THE W GULF. IN THE WAKE OF THE
COLD FRONTS...COOLER AND DRIER CONDITIONS ARE PRESENT.
ALSO...GALE CONDITIONS ARE FORECAST TO OCCUR FOR PORTIONS OF THE
MIDDLE AND EAST GULF DURING THE NEXT DAY.

CARIBBEAN SEA...
IN THE SW CARIBBEAN...A 1009 MB SURFACE LOW IS CENTERED E OF
NICARAGUA NEAR 12N82W. LOW LEVEL CONVERGENCE NEAR THIS SURFACE
LOW IS SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS S
OF 17N W OF 79W...INCLUDING PORTIONS OF PANAMA...COSTA
RICA...AND NICARAGUA. THIS ACTIVITY IS BEING ENHANCED BY UPPER
LEVEL DIFFLUENCE IN THE VICINITY OF AN UPPER RIDGE PRESENT OVER
THE W CARIBBEAN...WITH THE AXIS OF THIS UPPER RIDGE EXTENDING
FROM N COLOMBIA NEAR 12N72W TO 17N75W TO 20N84W TO E CUBA NEAR
21N76W. OVER THE E CARIBBEAN...A SURFACE TROUGH EXTENDS FROM
16N64W TO 13N65W TO N VENEZUELA NEAR 10N65W. DEEP LAYER DRY AIR
OVER THE E CARIBBEAN IS SUPPRESSING DEEP CONVECTION NEAR THIS
SURFACE TROUGH...WITH GENERALLY FAIR WEATHER PRESENT ACROSS THE
E CARIBBEAN. THE SURFACE COLD FRONT OVER THE E GULF OF MEXICO IS
EXPECTED TO ENTER THE NW CARIBBEAN OVER THE NEXT DAY.

ATLANTIC OCEAN...
A VIGOROUS DEEP LAYER TROUGH IS OVER THE E CONUS. STRONG UPPER
LEVEL DIVERGENCE...COMBINED WITH INSTABILITY AND STRONG DEEP
LAYER WIND SHEAR...IS GENERATING A LINE OF SHOWERS AND
THUNDERSTORMS EXTENDING FROM 31N77W TO 25N83W. THIS ACTIVITY IS
BEING ENHANCED BY LOW LEVEL CONVERGENCE IN THE VICINITY OF A
SURFACE COLD FRONT THAT EXTENDS FROM NE FLORIDA NEAR 31N82W TO
26N84W INTO THE S GULF. OVER THE NEXT DAY...THE COLD FRONT IS
FORECAST TO MOVE SOUTHEASTWARD ACROSS PORTIONS OF THE W ATLC. IN
THE WAKE OF THE COLD FRONT...RELATIVELY COOLER AND DRIER
CONDITIONS ARE PRESENT. ADDITIONALLY...GALE CONDITIONS ARE
FORECAST DURING THE NEXT DAY OVER PORTIONS OF THE W ATLC. TO THE
E...A 1025 MB SURFACE HIGH IS PRESENT NEAR 28N56W...WITH
SUBSIDENCE AND FAIR WEATHER IN THE VICINITY OF THE SURFACE HIGH.
FARTHER TO THE E...A SURFACE TROUGH EXTENDS FROM 27N37W TO
32N37W TO A 1012 MB SURFACE LOW NEAR 34N37W...WITH LOW LEVEL
CONVERGENCE NEAR THESE FEATURES RESULTING IN SCATTERED SHOWERS N
OF 29N BETWEEN 34W-41W. THIS ACTIVITY IS BEING ENHANCED BY
ATMOSPHERIC INSTABILITY IN THE VICINITY OF AN UPPER TROUGH WITH
AN AXIS EXTENDING FROM 26N41W TO 31N38W TO AN UPPER LOW NEAR
34N38W. ALSO...A SURFACE TROUGH EXTENDS FROM 31N34W TO 25N35W TO
20N40W TO 9N55W...WITH LOW LEVEL CONFLUENCE RESULTING IN
SCATTERED SHOWERS WITHIN 60 NM EITHER SIDE OF THIS FEATURE. THIS
ACTIVITY N OF 16N IS BEING ENHANCED BY UPPER LEVEL DIVERGENCE IN
THE VICINITY OF A 100-110 KT UPPER LEVEL JET MAXIMUM OVER THE E
PACIFIC. ACROSS THE E ATLC...A SURFACE WARM FRONT EXTENDS FROM
28N27W TO 32N29W...WITH SCATTERED SHOWERS WITHIN 90 NM EITHER
SIDE OF THIS FRONT. ALSO...A SURFACE COLD FRONT EXTENDING FROM
29N14W TO 29N11W EASTWARD ACROSS N AFRICA IS ASSOCIATED WITH AN
UPPER TROUGH OVER PORTIONS OF N AFRICA...AND A SURFACE TROUGH
EXTENDS FROM A 1011 MB SURFACE LOW OVER SENEGAL NEAR 13N14W TO
19N17W TO 25N16W...WITH DEEP LAYER DRY AIR INHIBITING DEEP
CONVECTION IN THE VICINITY OF THE SURFACE COLD FRONT...LOW...AND
TROUGH. ADDITIONALLY...AN UPPER RIDGE IS S OF 16N BETWEEN THE
AFRICAN COAST AND 39W...WITH AN UPPER HIGH NEAR 7N17W. UPPER
LEVEL DIFFLUENCE ASSOCIATED WITH THIS UPPER RIDGE AND UPPER HIGH
IS ENHANCING CONVECTION IN THE VICINITY OF THE ITCZ BETWEEN E OF
34W.

OF NOTE...NOVEMBER 30 MARKS THE CONCLUSION OF THE 2008 ATLANTIC
HURRICANE SEASON. DURING THIS SEASON...SIXTEEN NAMED TROPICAL
CYCLONES OCCURRED. OF THESE SIXTEEN...EIGHT WERE HURRICANES...OF
WHICH FIVE WERE MAJOR HURRICANES OF SAFFIR-SIMPSON CATEGORY
THREE STRENGTH OF STRONGER. THIS SEASON WAS THE FIRST EVER WHEN
SIX CONSECUTIVE TROPICAL CYCLONES MADE LANDFALL ON THE CONUS
MAINLAND. OVERALL...THE 2008 HURRICANE SEASON IS TIED AS THE
FOURTH MOST ACTIVE IN TERMS OF NUMBER OF NAMED STORMS AND MAJOR
HURRICANES...AND IS ALSO TIED AS FIFTH MOST ACTIVE IN TERMS OF
NUMBER OF HURRICANES SINCE 1944...THE BEGINNING OF THE AERIAL
RECONNAISSANCE ERA. FINALLY...THIS IS THE TENTH SEASON TO
PRODUCE ABOVE-NORMAL TROPICAL CYCLONE ACTIVITY SINCE 1995 WHEN
THE CURRENT ACTIVE HURRICANE ERA BEGAN. ADDITIONALLY...A TOTAL
OF 64 TROPICAL WAVES MOVED OFF THE COAST OF AFRICA THIS SEASON
WHICH IS NEAR THE SEASONAL AVERAGE.

$$
COHEN/GR


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