[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 032320
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SUN DEC 03 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...
METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N10W 5N25W 5N35W 5N45W 5N53W. THE
ITCZ IS FAIRLY QUIET WITH ONLY A FEW AREAS OF CONVECTION.
SCATTERED MODERATE IS FROM 3N-8N BETWEEN 34W-43W. ISOLATED
MODERATE IS FROM 1N-4N E OF 13W.

...DISCUSSION...
GULF OF MEXICO...
A STRONG MID/UPPER LEVEL RIDGE REMAINS PARKED IN THE NW
CARIBBEAN. THIS LEAVES THE GULF UNDER A MOIST SWLY UPPER LEVEL
FLOW REGIME PRODUCING CONSIDERABLE MID-HIGH LEVEL CLOUDINESS.
AT THE SFC...A FRONTAL BOUNDARY IS STATIONARY FROM N CENTRAL
FLORIDA INTO THE BAY OF CAMPECHE ALONG 29N83W 25N88W 19N93W.
LOW-LEVEL LIFT ALONG WITH UPPER LEVEL MOISTURE IN PLACE IS
GENERATING ISOLATED TO SCATTERED SHOWERS WITHIN 180 NM EITHER
SIDE OF THE SFC BOUNDARY. STRONG HIGH PRES IS BUILDING SWD
BEHIND THE FRONT ANALYZED AT AN IMPRESSIVE 1044 MB IN NRN
KANSAS. THE TIGHT PRES GRAD BETWEEN THE STRONG HIGH AND THE
FRONT IS GENERATING STRONG N-NE WINDS W OF THE FRONT ADVECTING
MUCH COOLER AND DRIER AIR. THESE NLY WINDS ARE NOW MAINLY IN THE
20-30 KT RANGE BUT ARE STRONGER IN THE SW GULF WHERE A GALE
WARNING IS IN EFFECT. THIS STRONG FLOW IS POOLING AND BANKING
THICK LOW-LEVEL CLOUDS AND DRIZZLE E OF THE SLOPES OF THE SIERRA
MADRE IN MEXICO. BECAUSE OF THIS THICK CLOUDINESS AND A TEMP
GRAD NOTED A STATIONARY FRONT WAS ADDED TO THE 21Z MAP ALONG THE
E SLOPES. AS A SHORTWAVE TROUGH...CURRENTLY ACROSS THE
PLAINS...MOVES E IT WILL ERODE THE STRONG UPPER HIGH IN THE
CARIB AND FORCE THE SFC FRONT SWD DOWN THE FLORIDA PENINSULA
OVER THE NEXT DAY OR TWO. THE STRONG SFC HIGH WILL ALSO MOVE E
KEEPING WINDS STRONG...ESPECIALLY IN THE SW GULF...OVER THE NEXT
COUPLE DAYS.

CARIBBEAN SEA...
A LARGE STRONG MID/UPPER LEVEL HIGH CENTERED IN THE NW CARIBBEAN
NEAR THE CAYMAN ISLANDS COVERS THE REGION W OF 65W. VERY DRY AIR
ALOFT EXISTS EVERYWHERE PROVIDING A STRONG MID-LEVEL CAP NOT
ALLOWING ANY OF THE TYPICAL TRADE WIND SHOWERS ACQUIRE MUCH
DEPTH. A LARGE UPPER LEVEL LOW IS MOVING W CENTERED NE OF THE
LEEWARD ISLANDS NEAR 19N59W. THE LESSER ANTILLES IS ON THE DRY W
SIDE OF THE SYSTEM WHICH IS KEEPING CONDITIONS QUIET.
HOWEVER...AS THE UPPER LOW/SFC TROUGH MOVES W INTO THE ERN CARIB
OVER THE NEXT COUPLE DAYS SOME SHOWER AND TSTM ACTIVITY WILL
LIKELY SPREAD INTO THE AREA. AT THE SFC...MODERATE TO STRONG
HIGH PRES TO THE N ALONG WITH THE LOW PRES TROUGH TO THE E IS
PRODUCING TRADE WINDS IN THE 20-25 KT RANGE ACROSS MUCH OF THE
AREA. THE COMBINATION OF THESE STRONG WINDS AND NE SWELL IS
GENERATING HAZARDOUS MARINE CONDITIONS. SFC WINDS WILL INCREASE
IN THE NW CARIB AS THE STRONG HIGH OVER THE U.S. SRN PLAINS
MOVES E. ELSEWHERE THE WINDS WILL GRADUALLY SUBSIDE AS THE PRES
GRAD WEAKENS.

THE ATLANTIC OCEAN...
AN AMPLIFIED RIDGE/TROUGH/RIDGE PATTERN DOMINATES MUCH OF THE
SUBTROPICAL AND TROPICAL ATLC. A STRONG BROAD MID/UPPER LEVEL
RIDGE CENTERED IN THE NW CARIBBEAN HAS RIDGING THAT EXTENDS
NEWARD TO BERMUDA. A LARGE UPPER LEVEL LOW CENTERED NE OF THE
LEEWARD ISLANDS NEAR 19N59W HAS CARVED OUT A PRONOUNCED WEAKNESS
IN THE RIDGING. THIS LOW HAS ITS HIGHEST MAGNITUDE AT UPPER
LEVELS BUT IT DOES HAVE A CLEAR SFC SIGNATURE WITH WINDS VEERING
IN SHIPS REPORTS AND AN EARLIER QSCAT PASS...ANALYZED AS A SFC
TROF ALONG 57W FROM 10N-24N. SCATTERED SHOWERS AND TSTMS ARE
LOCATED ON THE MOIST E SIDE OF THE UPPER LOW FROM 11N-23N
BETWEEN 50W-60W. THERE IS A SMALL WEAK UPPER LOW AND POSSIBLY A
RELATED SFC TROUGH NE OF THE MAIN ONE NEAR 29N48W GENERATING
ISOLATED SHOWERS WITHIN 120 NM E OF THE ILL-DEFINED CENTER. DRY
AIR ALOFT COVERS THE AREA W OF THE UPPER LOW NEAR THE LEEWARD
ISLANDS...WHICH INCLUDES ALL OF THE WRN ATLC...WITH THE
EXCEPTION OF THE NW CORNER JUST E OF THE N CENTRAL FLORIDA WHERE
THERE IS FORCING NEAR A FRONTAL BOUNDARY. AN UPPER LEVEL RIDGE
LIES IMMEDIATELY E OF THE UPPER LOW WITH THE RIDGE AXIS ROUGHLY
ALONG 40W CONTAINED S OF 25N EXTENDING DEEP INTO THE TROPICS.
SW-WLY WINDS AROUND THIS RIDGE HAS ADVECTED DEBRIS UPPER LEVEL
MOISTURE FROM THE SHOWERS AND TSTMS IN THE CENTRAL ATLC
ASSOCIATED WITH THE UPPER LOW. BROKEN TO OVERCAST MID-HIGH LEVEL
CLOUDINESS AND SCATTERED SHOWERS LIKELY EXISTS BETWEEN THE MAIN
UPPER LOW MENTIONED AND 30W S OF 28N. THE ERN MOST ATLC IS UNDER
A HIGHLY ELONGATED INVERTED TROUGH. AT THE SURFACE...MODERATE TO
STRONG HIGH PRES RIDGING DOMINATES THE ATLC. THIS RIDGING IS
BLEMISHED A BIT BY THE SFC TROUGH IN THE CNTRL CARIB. THE FAIRLY
TIGHT PRES GRAD IS GENERATING A LARGE AREA OF STIFF NE-E WINDS
AND HIGH SEAS.

$$
CANGIALOSI




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