AXNT20 KNHC 071200
TWDAT
TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.
...SPECIAL FEATURES...
TROPICAL STORM IDA IS CENTERED NEAR 17.4N 84.1W AT 07/1200 UTC
OR ABOUT 220
MILES...360 KM...SOUTHWEST OF GRAND CAYMAN ISLAND AND ABOUT 280
MILES...460 KM...SOUTHEAST OF COZUMEL MEXICO MOVING N AT 7 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB. MAXIMUM SUSTAINED
WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/ WMO HEADERS MIATCMAT1/WTNT21 KNHC
FOR MORE DETAILS. SCATTERED/NUMEROUS STRONG CONVECTION IS WITHIN
A 60 NM RADIUS OF 17.5N84W. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION COVERS THE REMAINDER OF THE
AREA FROM 16N-21N BETWEEN 78W-85W.
...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 36W/37W S OF 14N MOVING W NEAR 15 KT.
WAVE REMAINS WITHIN A BROAD AREA OF DEEP LAYERED MOISTURE ON THE
TOTAL PRECIPITABLE WATER IMAGERY. WAVE IS JUST TO THE SE OF AN
UPPER TROUGH AND BENEATH AN UPPER RIDGE WHICH IS DRAWING
MOISTURE AWAY FROM THE WAVE ITSELF. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS WITHIN 60 NM OF A LINE FROM 13N32W TO
16N37W.
TROPICAL WAVE IS ALONG 58W S OF 17N MOVING W NEAR 15 KT. WEAK
LOW LEVEL CURVATURE IS OBSERVED ON SATELLITE IMAGERY AND WAVE
REMAINS IN AN AREA OF SLIGHT UPPER LEVEL MOISTURE THUS NO
SIGNIFICANT DEEP CONVECTION OR SHOWER ACTIVITY.
...ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 7N9W 5N20W 7N35W 7N52W 8N61W.
CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 2N-11N
BETWEEN 24W-33W.
...DISCUSSION...
GULF OF MEXICO...
A 1028 MB HIGH IS CENTERED OVER EASTERN VIRGINIA WITH A SURFACE
RIDGE EXTENDING SW OVER TEXAS AND SE INTO THE W ATLC COVERING
GULF OF MEXICO N OF 25N GIVING MOST OF THE GULF EASTERLY FLOW.
THIS FLOW FILTERS INTO THE SW GULF AND BAY OF CAMPECHE NEAR A
SURFACE TROUGH THAT EXTENDS FROM 18N92W THROUGH A 1010 MB LOW
NEAR 19.5N95W TO 23N96W. THE SURFACE LOW/TROUGH IS SUPPORTED
ALOFT BY AN UPPER LEVEL SHORTWAVE TROUGH WITH AN AXIS EXTENDING
FROM NE MEXICO JUST S OF BROWNSVILLE TEXAS TO S MEXICO NEAR
VERACRUZ. THE REMAINDER OF THE GULF IS DOMINATED BY AN UPPER
RIDGE ANCHORED IN THE CENTRAL CARIBBEAN. THE SURFACE FEATURES
ALONG WITH DIFFLUENCE E OF THE UPPER LEVEL TROUGH AXIS ARE
GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS
S OF 26N BETWEEN 87W-97W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE MOVING WESTWARD THROUGH THE STRAITS OF FLORIDA
S OF 25N E OF 87W. THE NE GULF REMAINS CLEAR THIS MORNING.
CARIBBEAN SEA...
THE MOST SIGNIFICANT FEATURE FOR THE CARIBBEAN THIS MORNING IS
TROPICAL STORM IDA. THE UPPER LEVELS OF THE CARIBBEAN ARE
DOMINATED BY A LARGE UPPER RIDGE ANCHORED IN THE CENTRAL
CARIBBEAN NEAR 13N74W AND COVERS THE GULF OF MEXICO AND THE SW
ATLC AS WELL. A WEAK SURFACE TROUGH IS ANALYZED ALONG 77W S OF
14N TO THE COAST OF COLOMBIA AND IS GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS S OF 12N FROM 75W-79W. THE E
CARIBBEAN IS UNDER MODERATE/STRONG SUBSIDENCE AND DRIER AIR.
HOWEVER...ISOLATED LOW LEVEL FAST MOVING SHOWERS DOTS THE
REMAINDER OF THE CARIBBEAN USHERED IN ON MODERATE/STRONG
EASTERLY TRADEWINDS.
ATLANTIC OCEAN...
A SURFACE RIDGE CONTROLS THE W ATLC N OF 25N W OF 60W ANCHORED
ON A 1028 MB HIGH CENTERED OVER EASTERN VIRGINIA. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 60 NM OF LINE FROM
24N69W INTO THE GULF OF MEXICO THROUGH THE STRAITS OF FLORIDA
NEAR 24N80W. FARTHER EAST...A COLD FRONT ENTERS THE DISCUSSION
AREA NEAR 32N53W EXTENDING SW TO 24N67W WITH A SURFACE TROUGH
EXTENDING FROM 32N52W TO 23N61W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE WITHIN 120 NM E OF THE COLD FRONT N OF 27N AND
SCATTERED SHOWERS FROM 23N-27N BETWEEN 54W AND THE COLD FRONT.
THE FRONTAL SYSTEM IS SUPPORTED ALOFT BY AN UPPER LEVEL TROUGH N
OF 26N W OF 52W. THE E ATLC IS UNDER THE INFLUENCE OF A SURFACE
RIDGE ANCHORED ON A 1034 MB HIGH CENTERED OVER THE AZORES. AN
UPPER LEVEL TROUGH IS OVER THE E ATLC EXTENDING AN AXIS FROM
32N30W INTO THE TROPICS TO 15N48W. UPPER LEVEL DIFFLUENCE EAST
OF THE TROUGH AXIS IS GENERATING POSSIBLE SCATTERED SHOWERS N OF
THE TROPICAL WAVE ALONG 36W/37W COVERING THE AREA FROM 16N-27N
BETWEEN 35W-43W.


forecast by WALLACE
updated at 705 AM EST SAT NOV 07 2009

AXPZ20 KNHC 071000
TWDEP
TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT NOV 07 2009
TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM
THE EQUATOR TO 32N...EAST OF 140W.
BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0815 UTC.
...TROPICAL LOWS...
LOW PRES CENTERED NEAR 12N91W ESTIMATED AT 1006 MB AND IS NOW
MOVING N SLOWLY IN RESPONSE TO THE UPPER TROUGH IMMEDIATELY TO
ITS W WHICH IS ALSO CONTRIBUTING BOTH SOUTHWESTERLY WIND SHEAR
AND DRY AIR WHICH IS BEING ENTRAINED BY THE LOW. THE SYSTEM IS
EXPECTED TO DISSIPATE TO A TROUGH OVER THE NEXT 24 HOURS WITHIN
THIS HOSTILE ENVIRONMENT. CURRENTLY...SCATTERED MODERATE WITH
ISOLATED STRONG CONVECTION IS DISPLACED FROM THE LOW LEVEL
CENTER...BETWEEN 60 NM AND 180 NM IN THE NE QUADRANT OF THE LOW.
TWO SHIP REPORTS IN THE EASTERN SEMICIRCLE OF THE LOW REPORTED
WINDS IN THE 25 TO 30 KT RANGE AT 0600 UTC...BUT THESE WINDS
SHOULD RAPIDLY DIMINISH TODAY AS THE LOW WEAKENS.
LOW PRES CENTERED NEAR 12N116W IS ESTIMATED AT 1010 MB. THE
SURFACE LOW IS UNDER AN UPPER ANTICYCLONE...AND THE ASSOCIATED
UPPER DIFFLUENCE HAS BEEN ENHANCING CONVECTION. SCATTERED
MODERATE WITH ISOLATED STRONG CONVECTION LIES WITHIN 180 NM NW
AND SE QUADRANTS OF THE LOW. THIS LOW IS EXPECTED TO WEAKEN OVER
THE NEXT 24-36 HOURS AS THE UPPER JET TO ITS N SINKS
SOUTHWARD...PROVIDING 30 TO 40 KT OF SHEAR OVER THE SYSTEM.
...ITCZ...
THE ITCZ AXIS EXTENDS ALONG 07N77W TO 11N87W TO 07N97W TO
12N115W TO 08N140W. SCATTERED MODERATE CONVECTION CAN BE FOUND
NEAR PANAMA WITHIN 60 NM N AND 120 NM S OF THE ITCZ AXIS BETWEEN
78W AND 82W. SCATTERED MODERATE TO STRONG CONVECTION LIES WITHIN
90 NM S OF THE ITCZ AXIS BETWEEN 98W AND 101W.
...DISCUSSION...
N OF 20N...
AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR 08N113W WITH A RIDGE
AXIS EXTENDING NE TO MANZANILLO...MEXICO AND CONTINUING N INTO
TEXAS. AN UPPER LOW LIES OVER THE NORTHERN GULF OF CALIFORNIA
NEAR 29N113W AND IS APPROACHING THIS RIDGE AXIS FROM THE W. THE
TROPICAL MOISTURE PLUME THAT EXTENDED FROM THE ITCZ REGION TO
THE EASTERN EDGE OF THIS UPPER LOW THIS TIME YESTERDAY HAS BEEN
CUT OFF. ONLY HIGH CLOUDS REMAIN...PRIMARILY OVER THE NORTHERN
HALF OF THE GULF OF CALIFORNIA AS WELL AS OVER NW MAINLAND
MEXICO. THIS UPPER LOW WILL CONTINUE E AWAY FROM THE FORECAST
AREA OVER THE NEXT FEW DAYS. THERE IS LITTLE INDICATION OF THE
UPPER LOW AT THE SURFACE WHERE A HIGH PRES RIDGE STEMMING FROM A
1032 MB HIGH NEAR 36N152W DOMINATES THE REMAINDER OF NORTH
WATERS. THE PRES GRADIENT BETWEEN THIS HIGH AND LOW PRES OVER
THE GULF OF CALIFORNIA HAS BROUGHT 20 KT NORTHERLY WINDS OFF THE
W COAST OF BAJA CALIFORNIA. THESE WINDS SHOULD DISSIPATE OVER
THE NEXT FEW HOURS AS A COLD FRONT BEARS DOWN ON THE HIGH PRES
SYSTEM FROM THE NW AND WEAKENS THE RIDGING. WHILE THIS FRONT IS
EXPECTED TO DISSIPATE BEFORE IT CAN REACH FORECAST WATERS...LONG
PERIOD NW SWELL FROM THE SYSTEM IS ALREADY BEGINNING TO PUSH
INTO NW WATERS WITH SIGNIFICANT WAVE HEIGHTS INCREASING TO 18 FT
OVER NW WATER THIS MORNING. HIGHEST SEAS WILL SHIFT E QUICKLY
TODAY ACROSS N WATERS...WITH THE LEADING EDGE OF THE SWELL TRAIN
PROGRESSING SE.
S OF 20N...
ASIDE FROM THE LOW PRES SYSTEMS DESCRIBED ABOVE AND THE GAP
WINDS DESCRIBED BELOW...EASTERLY TRADE WINDS ARE THE DOMINANT
FEATURE OF NOTE. 20 TO 25 KT TRADES ARE CURRENTLY LIMITED TO
BETWEEN 10N AND 20N W OF 127W...WITH A SMALL AREA OF 20 TO 25 KT
WINDS ASSOCIATED WITH THE LOW PRES SYSTEM NEAR 12N116W. THE AREA
OF STRONGEST TRADE WINDS WILL SHIFT S IN RESPONSE TO THE
AFOREMENTIONED REORGANIZATION OF THE HIGH PRES SYSTEM TO THE
NORTH. ANOTHER WEAK LOW PRES SYSTEM LIES NEAR 10N108W. ACCORDING
TO THE 0504 ASCAT PASS...THE LOW HAS A SMALL AREA OF 20 TO 25 KT
WINDS WITHIN 90 NM IN ITS N QUADRANT. SCATTERED MODERATE
CONVECTION CAN CURRENTLY BE FOUND WITHIN 90 NM NW AND 60
NM SE SEMICIRCLES OF THE LOW WHICH NOW LIES UNDER THE
ANTICYCLONE IN A FAVORABLE AREA FOR CONVECTION. CONDITIONS
SHOULD BECOME MORE HOSTILE FOR THE SYSTEM OVER THE NEXT DAY OR
TWO...AND THIS LOW IS EXPECTED TO DISSIPATE WITH LITTLE FANFARE.
GAP WINDS...
A PARTIAL ASCAT PASS FROM 0324 UTC SHOWED WINDS IN THE 30 TO 33
KT RANGE IN THE GULF OF TEHUANTEPEC. CONSIDERING THE PASS
OMITTED A PORTION OF THE AREA BELIEVED TO HAVE THE STRONGEST
WINDS AND THE FACT THAT ASCAT GENERALLY RUNS LOW WITH WINDS NEAR
GALE FORCE AND HIGHER...THERE IS LIKELY STILL A GALE HERE THAT
WILL CONTINUE THROUGH THE MORNING HOURS. HOWEVER...THERE IS A
CONSIDERABLE AMOUNT OF UNCERTAINTY WITH THE FORECAST FOR THE
STRENGTH AND POSITION OF LOW PRES IN THE BAY OF CAMPECHE...THE
PERSISTENT LOW PRES NEAR 12N91W THAT IS NOW DRIFTING N...AND
TROPICAL STORM IDA NOW OVER THE EASTERN GULF OF HONDURAS AND
FORECAST TO MOVE NORTHWARD AND STRENGTHEN. ALL OF THESE FACTORS
WILL INFLUENCE THE WIND...OR LACK OF WIND...IN THE GULF OF
TEHUANTEPEC OVER THE NEXT FEW DAYS. DEPENDING ON THE ORIENTATION
OF THE LOW PRES CENTERS N OF THE AREA...ANOTHER N SURGE MAY
OCCUR AS EARLY AS SUN IN THE GULF OF TEHUANTEPEC.


forecast by SCHAUER