[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 221712
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED NOV 22 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.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N13W 6N24W 4N35W 4N47W 3N53W.
SCATTERED SHOWERS AND TSTMS ARE WITHIN 180 NM EITHER SIDE OF THE
AXIS BETWEEN 28W-40W. SOME OF THIS ACTIVITY MIGHT BE ASSOCIATED
WITH A WEAK LOW AMPLITUDE TROPICAL WAVE ALONG 37W/38W.
HOWEVER...BECAUSE OF ITS VERY WEAK NATURE AND DUE TO THE HOSTILE
UPPER LEVEL ENVIRONMENT THIS WEAK FEATURE WAS NOT ADDED TO THE
MAP.

...DISCUSSION...
THE GULF OF MEXICO...
A STRONG VERTICALLY STACKED OCCLUDED LOW PRES SYSTEM HAS BEEN
SLOWLY DRIFTING NE OFF THE SE U.S. COASTLINE. THE GULF LIES TO
THE W...DRY SIDE...OF THIS SYSTEM WITH STRONG NLY MID-UPPER
LEVEL FLOW AND STRONG SUBSIDENCE NOTED ACROSS NEARLY THE ENTIRE
AREA. AN UPPER LEVEL RIDGE IS BUILDING EASTWARD ACROSS THE WRN
GULF WEAKENING THE UPPER LEVEL WINDS THERE. AT THE SFC...HIGH
PRES CONTINUES TO DOMINATE ANCHORED BY A 1027 MB HIGH IN THE NW
GULF NEAR 27N94W. THIS HIGH PRES RIDGING IS FURTHER S AND WEAKER
THAN THE PAST FEW DAYS ALLOWING WINDS TO SUBSIDE SUBSTANTIALLY
IN THE WRN GULF. STRONGER WINDS...15-20 KT WITH ONE OR TWO BUOYS
REPORTING SLIGHTLY HIGHER...STILL EXIST IN THE CNTRL AND
ERN GULF. THESE WINDS CONTINUE TO ADVECT COLD AIR INTO THE
REGION. THIS MORNING TEMPS WERE IN THE VERY UNSEASONABLE 30'S
AND 40'S ACROSS FLORIDA WITH EVEN SOME WET SNOW FLAKES MIXED IN
WITH LIGHT RAIN/DRIZZLE ACROSS THE CNTRL AND NRN PART OF THE
STATE LATE LAST NIGHT. THINNING STRATO-CU CLOUDS STILL EXIST IN
THE SRN GULF. THE STACKED LOW OFF THE SE COAST WILL PULL NE AT A
FASTER RATE AS THE UPPER RIDGE IN THE WRN GULF BUILDS E. THIS
UPPER LEVEL PATTERN ALONG WITH THE CONTINUED WEAKENING PRES GRAD
AT THE SFC WILL ALLOW THE AIRMASS TO MODIFY GRADUALLY RETURNING
TEMPS TO NORMAL VALUES.

THE CARIBBEAN SEA...
A SHARP AIRMASS DIFFERENCE CONTINUES TO BE VERY EVIDENT IN THE
CARIB. THE DIVIDER IS A STRONG FRONT WHICH EXTENDS FROM THE ATLC
ACROSS WRN HAITI THEN STATIONARY VERY FAR S TO PANAMA NEAR
10N79W. BEHIND THE FRONT...NOTABLE COOL AND DRY AIR IS STILL BE
ADVECTED INTO THE REGION ON STRONG NLY WINDS. THESE WINDS HAVE
DECREASED THIS MORNING ALLOWING THE GALE WARNING TO EXPIRE BUT
THEY ARE STILL RATHER STRONG JUST BELOW GALE FORCE. CLUSTERS OF
SCATTERED MODERATE CONVECTION IS LOCATED WITHIN 120 NM EITHER
SIDE OF THE STALLED FRONT. THIS ACTIVITY IS BEING ENHANCED BY
UPPER LEVEL DIFFLUENCE BETWEEN A HIGHLY AMPLIFIED STRETCHED
UPPER RIDGE AND THE STRONG TROUGH ACROSS THE SW ATLC AND NW
CARIB. GFS HAS DONE A PRETTY GOOD JOB IN SHOWING THE MOISTURE
SWATH THINNING SLIGHTLY AND SHRINKING IN WIDTH OVER THE PAST FEW
DAYS. THE MODEL CONTINUES TO SHOW THAT TREND WITH IT GETTING
PUSHED BACK TO THE W BY THE TRADES. THE ERN ATLC IS QUIET WITH
UPPER LEVEL CONFLUENCE ...BETWEEN A BROAD UPPER LEVEL LOW OVER
VENEZUELA AND UPPER RIDGING IN THE CNTRL ATLC...PRODUCING PLENTY
OF DRY STABLE AIR ALOFT E OF 70W. TRADE WINDS E OF THE FRONT ARE
LIGHT TO MODERATE SPREADING TYPICAL ISOLATED SHALLOW SHOWERS
ACROSS THE SEA. A PATCH OF SOMEWHAT DEEPER MOISTURE...ASSOCIATED
WITH THE MOIST FLOW OF THE UPPER LOW OVER VENEZUELA...IS LOCATED
JUST E OF THE LESSER ANTILLES. SOME OF THIS MAY MOVE ACROSS THE
ISLANDS TONIGHT OR TOMORROW.

THE ATLANTIC OCEAN...
A PRONOUNCED TROUGH/RIDGE/TROUGH PATTERN EXISTS ACROSS THE
SUBTROPICAL AND TROPICAL ATLC. A STRONG COMPLEX OCCLUDED LOW
PRES SYSTEM WITH SEVERAL EMBEDDED LOW CENTERS OFF THE SE
COASTLINE IS MOVING TO THE NE. DOPPLER RADAR CONTINUES TO SHOW
BANDS OF NUMEROUS SHOWERS AND TSTMS ON THE COLD BACK SIDE OF THE
LOW AFFECTING MUCH OF THE CAROLINAS. THE STRONG TRAILING COLD
FRONT EXTENDS FROM THE ERN MOST LOW ALONG 32N68W 26N70W ACROSS
THE SE BAHAMAS AND DEEP INTO THE CARIB WHERE IT HAS STALLED.
THIS SFC BOUNDARY ALONG WITH UPPER DIFFLUENCE IS GENERATING A
CONSIDERABLE AMOUNT OF MOISTURE BETWEEN 66W-73W. W OF THE
FRONT...MUCH COLDER AIR IS ADVECTED BY STRONG W-NWLY WINDS. A
STRONG MID-UPPER LEVEL RIDGE LIES TO THE E OF THE COMPLEX
WEATHER PATTERN CENTERED IN THE SUBTROPICS NEAR 30N59W. A HIGHLY
ELONGATED TROUGH IS LOCATED E OF THE RIDGE WITH SEVERAL UPPER
LEVEL LOWS EMBEDDED FROM A LARGE CUT OFF NEAR 26N25W TO A SMALL
UPPER LOW NEAR 24N47W EXTENDING DEEP INTO THE TROPICS TO A BROAD
UPPER LOW OVER VENEZUELA. PLENTY OF DRY AIR ALOFT EXISTS ACROSS
MOST OF THE AREA BETWEEN 32W-66W N OF 20N. S OF 20N E OF THE
CARIBBEAN...THERE IS A CONSIDERABLE AMOUNT OF MOISTURE ADVECTED
FROM THE ITCZ BY SWLY UPPER LEVEL FLOW AND DRIVEN EASTWARD BY A
WLY JET. THIS MOISTURE DOES NOT APPEAR TO BE VERY
CONVECTIVE...BASED ON IR IMAGERY...ALTHOUGH SCATTERED SHOWERS
ARE LIKELY OVER A LARGE AREA BETWEEN 23W-60W MOSTLY S OF 18N. AT
THE SFC...HIGH PRES IS THE RULE E OF THE WRN ATLC FRONTAL
BOUNDARY ANCHORED BY A 1030 MB HIGH NEAR 34N47W AND A 1029 MB
HIGH S OF THE AZORES NEAR 35N24W. THIS STRONG RIDGING IS
INTERRUPTED A BIT BY A WEAK 1018 MB LOW NEAR 23N34W...WHICH IS
ASSOCIATED WITH THE LARGE CUT OFF UPPER SYSTEM MENTIONED. THE
LOW IS ONLY A SWIRL OF LOW CLOUDS WITH SCATTERED SHOWERS WELL NE
OF THE CENTER FROM 23N-27N BETWEEN 26W-29W.

$$
CANGIALOSI


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