[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211723
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST TUE NOV 21 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 1715 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 9N13W 6N26W 4N37W 3N46W 3N54W. THE
ITCZ IS FAIRLY QUIET WITH ONLY ISOLATED MODERATE FROM 4N-9N
BETWEEN 26W-30W. ELSEWHERE SCATTERED SHOWERS ARE WITHIN 300 NM
EITHER SIDE OF THE AXIS.

...DISCUSSION...
THE GULF OF MEXICO...
THE STRONG TROUGH THAT WAS DIGGING ACROSS THE SRN U.S. YESTERDAY
HAS CUT OFF OVER N FLORIDA/S GEORGIA. THIS WAS WELL
FORECAST BY MANY OF THE MODELS. THE GULF LIES TO THE W...DRY
SIDE...OF THIS SYSTEM WITH STRONG NLY MID-UPPER LEVEL FLOW AND
MODERATE TO STRONG SUBSIDENCE NOTED ACROSS NEARLY THE ENTIRE
AREA. THERE IS SOME BROKEN MOISTURE ACROSS THE SRN BAY OF
CAMPECHE S OF 20N...BUT THIS IS LIKELY ONLY PRODUCING ISOLATED
SHOWERS. AT THE SFC...STRONG HIGH PRES COVERS THE ENTIRE AREA
ANCHORED BY A 1033 MB HIGH IN NRN LOUISIANA. THE BIG STORY
CONTINUES TO BE THE UNSEASONABLY COLD AIR AND STRONG NLY WINDS
DUE TO THE TIGHT PRES GRAD BETWEEN THIS STRONG HIGH AND A SFC
LOW OFF THE FLORIDA/GEORGIA COAST. NLY WINDS ARE STRONGEST IN
THE E AND CENTRAL GULF WHERE SEVERAL BUOYS ARE REPORTING WINDS
BETWEEN 20-30 KT. CONDITIONS ARE SUBSIDING AND DEVELOPING AN
EASTERLY COMPONENT IN THE NW GULF...CLOSE TO THE SFC HIGH
CENTER. BROKEN STRATO-CU CLOUDS ARE WIDESPREAD ACROSS THE E
GULF...THESE CLOUDS ARE THICKEST IN THE EXTREME ERN GULF WHERE
DOPPLER RADAR IS INDICATING SCATTERED SHOWERS OFF THE W COAST
FROM TAMPA BAY SWD. THE STACKED LOW OFF THE FL/GA COAST WILL
BEGIN TO PULL NE AS AN UPPER RIDGE BUILDS OVERHEAD LATER THIS
WEEK. THIS WILL ALLOW THE AIRMASS TO MODIFY...HOWEVER A COUPLE
MORE DAYS OF BELOW NORMAL TEMPS IN THE CNTRL AND ERN GULF ARE
STILL EXPECTED BEFORE IT DOES SO.

THE CARIBBEAN SEA...
A FAIRLY SHARP AIRMASS DIFFERENCE EXISTS IN THE CARIB. THE
DIVIDER IS A STRONG COLD FRONT WHICH EXTENDS FROM THE ATLC
ACROSS THE BAHAMAS/ERN CUBA EXTENDING SWD TOWARDS THE COAST OF
PANAMA NEAR 10N82W. BEHIND THE FRONT...COOLER AND NOTABLE DRIER
AIR IS ADVECTED INTO THE REGION ON STRONG NLY WINDS. THESE WINDS
HAVE REACHED GALE FORCE S OF 18N BETWEEN 80W-85W. STRONG WINDS
AND HIGH SEAS ARE ALSO REPORTED FROM SHIPS IN THE YUCATAN
CHANNEL. FOR MORE DISCUSSION ON THIS UNSEASONABLE AIRMASS REFER
TO THE GULF OF MEXICO SECTION AND FOR WINDS AND SEAS REFER TO
MIAOFFNT3 AND MIAOFFNT4. ACTIVE WEATHER...IN TERMS OF SHOWERS
AND TSTMS...LIES TO THE E OF THE FRONT. A PRE-FRONTAL TROUGH IS
ANALYZED ABOUT 120-150 NM AHEAD OF THE FRONT FROM THE SE BAHAMAS
SWD ALONG 17N76W 13N79W TO PANAMA. SFC OBSERVATIONS AND VIS
IMAGES INDICATE A WIND SHIFT AND LINE OF LOW-LEVEL CONVERGENCE
WHICH WAS THE REASON OF ANALYZING THIS FEATURE AHEAD OF THE MAIN
BOUNDARY. SCATTERED SHOWERS AND TSTMS ARE WITHIN 150 NM AHEAD OF
THE FRONT. HOWEVER MORE IMPRESSIVE ACTIVITY...NUMEROUS MODERATE
CONVECTION...IS NEAR THE BASE OF THE FRONT S OF 13N BETWEEN
75W-82W. NUMEROUS MODERATE IS ALSO AHEAD OF THE TROUGH/FRONT
FROM 12N-18N BETWEEN 72W-76W. SOME OF THIS STRONGER ACTIVITY IS
BEING ENHANCED BY UPPER LEVEL DIFFLUENCE BETWEEN A HIGHLY
AMPLIFIED STRETCHED UPPER RIDGE AND THE STRONG TROUGHING ACROSS
THE SW ATLC/GULF AND NW CARIB. THE ERN ATLC IS QUIET WITH UPPER
LEVEL CONFLUENCE PRODUCING PLENTY OF DRY STABLE UPPER LEVEL AIR
E OF  69W. GFS SHOWS THE DEEP MOISTURE SWATH REMAINING NEARLY
STATIONARY BUT SHRINKING IN SIZE AND GRADUALLY WEAKENING OVER
THE NEXT COUPLE DAYS IN THE CNTRL/WRN CARIBBEAN.

THE ATLANTIC OCEAN...
A HIGH AMPLIFIED PATTERN LIES ACROSS THE ATLC BASIN. A LARGE
STACKED LOW IS OFF THE SE COAST...THE MID-UPPER LEVEL CENTER IS
ALONG THE FL/GA COAST WHILE THE 1010 MB SFC LOW IS A LITTLE
FURTHER SE CENTERED NEAR 30N78W. DOPPLER RADAR SHOWS BANDS OF
NUMEROUS SHOWERS AND TSTMS N OF 28N...AFFECTING MUCH OF THE
CAROLINAS. THIS LOW IS BECOMING OCCLUDED WITH THE COLD FRONT
EXTENDING FROM THIS LOW ALONG 32N76W ACROSS THE CENTRAL BAHAMAS
AND DEEP INTO THE CARIB. A PRE-FRONTAL TROUGH STRETCHES FROM
31N75W TO THE WINDWARD PASSAGE. THESE SFC BOUNDARIES ALONG WITH
UPPER DIFFLUENCE IS GENERATING A CONSIDERABLE AMOUNT OF MOISTURE
BETWEEN 65W-77W. W OF THE FRONT...MUCH COLDER AND DRIER AIR
ADVECTED BY STRONG NWLY WINDS EXIST WITH A GALE WARNING IN PLACE
FOR THE AREA N OF 28N W OF 78W. A STRONG TITLED MID-UPPER RIDGE
LIES TO THE E OF THE COMPLEX WEATHER PATTERN WITH THE AXIS
EXTENDING FROM HISPANIOLA NORTHEASTWARD TO WELL BEYOND 32N57W. A
NARROW TROUGH IS LOCATED TO THE E OF THE RIDGE WITH SEVERAL
UPPER LEVEL LOWS EMBEDDED FROM 32N39W TO 23N45W EXTENDING DEEP
INTO THE TROPICS TO AN UPPER LOW NEAR 17N53W. PLENTY OF DRY AIR
LIES ACROSS MOST OF THE AREA BETWEEN 40W-67W EXCEPT FOR AN AREA
OF SCATTERED SHOWERS ON THE S AND E SIDE OF THE SRN-MOST UPPER
LOW FROM 6N-12N BETWEEN 43W-60W. THE REMAINDER OF THE ATLC...E
OF 38W...IS DOMINATED BY A LARGE CUT OFF MID/UPPER LEVEL LOW
CENTERED NEAR 28N24W. AN ASSOCIATED SFC LOW HAS DEVELOPED WITH
SEVERAL MESO-SWIRLS ROTATING AROUND A MEAN CENTER NEAR 26N29W.
THIS SFC SYSTEM IS VERY WEAK...ANALYZED AT 1017 MB...ONLY
GENERATING ISOLATED SHOWERS TO THE NE OF THE LOW WITHIN 400 NM.
AT THE SFC...A 1033 MB HIGH IS CENTERED OVER THE AZORES. THIS
STRONG RIDGING DOMINATES THE CENTRAL AND ERN ATLC.

$$
CANGIALOSI


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