AXNT20 KNHC 201756
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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.
...ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 8N12W 6N25W 7N41W 8N46W 7N59W.
SCATTERED MODERATE CONVECTION IS FROM 3N-8N BETWEEN 20W-36W.
SIMILAR CONVECTION IS FOCUSED ALONG A SURFACE TROUGH EMBEDDED
WITHIN THE ITCZ AXIS AND ANALYZED FROM 11N39W TO 5N45W. THE
CONVECTION COVERS AN AREA FROM 6N-10N BETWEEN 40W-47W.
...DISCUSSION...
GULF OF MEXICO...
AN UPPER LEVEL SHORTWAVE TROUGH IS PROGRESSING EASTWARD ACROSS
THE TEXAS AND OKLAHOMA PANHANDLE. THIS UPPER TROUGH SUPPORTS A
COLD FRONT MOVING ACROSS EASTERN TEXAS AND IS INDUCING
CYCLOGENESIS ACROSS THE NW GULF WATERS AS A DEVELOPING 1013 MB
LOW IS CENTERED NEAR 27N95W. A WARM FRONT EXTENDS EAST FROM THE
LOW TO 25N91W. LOW-LEVEL CONVERGENCE NEAR AND NORTH OF THE WARM
FRONT ALONG WITH A ZONE OF UPPER LEVEL DIFFLUENCE LOCATED NORTH
OF THE WARM FRONT AND EAST OF THE UPPER LEVEL TROUGH IS
GENERATING NUMEROUS SHOWERS AND TSTMS N OF 26N W OF 91W.
PRIMARILY W-SW ZONAL UPPER LEVEL FLOW IS NOTED ON WATER VAPOR
IMAGERY ACROSS THE REMAINDER OF THE GULF. THIS ALONG WITH A
SURFACE RIDGE EXTENDING FROM THE SE CONUS ACROSS THE EASTERN
GULF AND FLORIDA PENINSULA IS PROVIDING GENERALLY FAIR SKIES E
OF 90W AND ACROSS THE BAY OF CAMPECHE.
CARIBBEAN SEA...
AN UPPER LEVEL RIDGE WITH AXIS EXTENDING FROM CENTRAL AMERICA TO
CUBA AND HISPANIOLA COVERS THE CARIBBEAN W OF 65W. STRONG
SUBSIDENCE IS NOTED ON WATER VAPOR IMAGERY WITH ONLY A FEW
ISOLATED SHOWERS OCCURRING FROM 13N-17N BETWEEN 77W-81W. ALSO...
ISOLATED SHOWERS ARE OCCURRING OVER THE SW CARIBBEAN...WESTERN
PANAMA...AND COSTA RICA S OF 11N W OF 81W. THE REMAINDER OF THE
CARIBBEAN E OF 65W IS UNDER THE INFLUENCE OF AN UPPER LEVEL
TROUGH OVER THE WESTERN TROPICAL ATLC WITH AXIS ALONG 50W. DRY
NW FLOW ALOFT IS OVER PUERTO RICO AND THE LESSER ANTILLES...
HOWEVER...HIGHER VALUES OF TOTAL PRECIPITABLE WATER STRETCH
ACROSS THE EASTERN CARIBBEAN WITH LOW-LEVEL SHOWERS OCCURRING N
OF 16N BETWEEN 65W-70W AND ALSO EAST OF THE LESSER ANTILLES
FROM 10N-16N BETWEEN 53W-61W. THIS INCREASED LOW-LEVEL MOISTURE
FIELD WILL CONTINUE TO PROVIDE POSSIBLE ISOLATED SHOWERS
THROUGHOUT THE AFTERNOON AND EVENING HOURS OVER THE NE CARIBBEAN.
ATLANTIC OCEAN...
AN UPPER LEVEL SHORTWAVE TROUGH LOCATED OVER THE NE CONUS AND
EASTERN CANADA SUPPORTS A DISSIPATING STATIONARY FRONT THAT
PASSES THROUGH 32N76W TO NEAR CAPE CANAVERAL AND INTO THE SE
GULF OF MEXICO. A SURFACE TROUGH EXTENDS FROM A 1014 MB LOW
NEAR 31N75W TO 28N74W ACROSS THE CENTRAL BAHAMAS TO 23N78W WITH
ISOLATED SHOWERS OCCURRING WITHIN 60 NM EITHER SIDE OF THE
SURFACE TROUGH AND STATIONARY FRONT. FARTHER EAST...AN UPPER
LEVEL TROUGH IS ACROSS THE NE NORTH ATLC AND SUPPORTS A
STATIONARY FRONT THAT ENTERS THE DISCUSSION AREA NEAR 32N28W AND
EXTENDS W-SW TO A 1016 MB LOW CENTERED NEAR 27N50W. THE
STATIONARY FRONT CONTINUES W-NW FROM THE LOW ALONG 29N60W TO THE
PREVIOUSLY MENTIONED 1014 MB LOW CENTERED NEAR 31N75W IN THE W
ATLC. SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN 120 NM
EITHER SIDE OF THE ENTIRE STATIONARY BOUNDARY. AIDED BY UPPER
LEVEL DIFFLUENCE ALOFT...SCATTERED SHOWERS FOCUSED NEAR THE 1016
MB LOW ARE BEING ENHANCED FROM 23N-30N BETWEEN 40W-52W. A
SURFACE TROUGH IS ANALYZED FROM PUERTO RICO TO 25N63W. SCATTERED
SHOWERS ARE PRIMARILY E OF THE TROUGH FROM 18N-25N BETWEEN
58W-65W. ACROSS THE CENTRAL ATLC...A SURFACE TROUGH EXTENDS FROM
17N40W TO 24N36W AND ANOTHER SURFACE TROUGH IS FROM 18N45W TO
24N44W WITH POSSIBLE ISOLATED SHOWERS N OF 18N TO THE STATIONARY
FRONT BETWEEN 34W-46W.


forecast by HUFFMAN
updated at 105 PM EST FRI NOV 20 2009

AXPZ20 KNHC 202202
TWDEP
TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI NOV 20 2009
TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM
THE EQUATOR TO 32N...EAST OF 140W.
BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2115 UTC.
...ITCZ...
THE ITCZ AXIS EXTENDS FROM 07N77W TO 04N80W TO 06N91W TO 05N106W
TO 08N119W TO 06.5N140W. SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION WITHIN 150 NM S OF AXIS E OF 81W...AND WITHIN 240 NM
N OF AXIS AND 90 NM S OF AXIS W OF 116W.
...DISCUSSION...
W OF 115W...A DEEP LAYER TROUGH EXTENDING FROM ALONG THE COASTS
OF WASHINGTON-OREGON-N CAL TO 23N127W WAS DIGGING E-SE ON THE
EAST SIDE OF REX BLOCK CENTERED ON THE LARGE RIDGE N OF HAWAII.
AN ASSOCIATED COLD FRONT EXTENDS FROM NRN CALIFORNIA TO 30N133W
TO 28N40W AND CONTINUES WWD AS A SHEAR AXIS. THE FRONT WAS
SHIFTING ESE AND TOWARDS CENTRAL CALIFORNIA AND NE PORTIONS OF
THE FORECAST AREA. A 1020 MB HIGH NEAR 27N132W WAS
COLLAPSING...WITH THE STRONGER CENTRAL PACIFIC RIDGE...CENTERED
ON A 1027 MB SURFACE HIGH ALONG 33N AND N OF HAWAII...WAS
SLIDING AND BUILDING EWD BEHIND THE COLD FRONT. RECENT
SCATTEROMETER PASSES SHOW MODERATE TO FRESH 20-25 KT TRADE WINDS
S OF THE HIGH PRES FROM GENERALLY 20-22N TO THE NRN FRINGES OF
THE ITCZ ALONG 07.5N FROM 114W WWD BEHIND 140W. THE RESULTANT
WIND WAVES WERE MIXING WITH A FADING PULSE OF NW SWELL TO
PRODUCE SEAS OF 8 TO 11 FT N OF 10N AND W OF 115W...WITH SEAS UP
12 TO 14 FT FROM 17N138W AND DOWNWIND...IN THE STRONGEST NE
TRADE WIND FLOW. FARTHER E...THE TRADE WIND FLOW HAS DIMINISHED
SLIGHTLY FROM YESTERDAY AS THE HIGH TO THE NORTH CONTINUES TO
WEAKEN. THESE FRESH TRADES WILL EXPAND AND SPREAD FARTHER E
DURING THE NEXT 24 HOURS AS THE CENTRAL PACIFIC HIGH CONTINUES
TO BUILD E BEHIND THE FRONT N OF THE AREA. THE FRONT ITSELF IS
EXPECTED TO BECOME DIFFUSE BY SAT NIGHT ACROSS NE PORTIONS OF
THE AREA AS THE ASSOCIATED UPPER DYNAMICS LIFT OUT. MEANWHILE
DIVERGENT FLOW ALOFT ON THE RIGHT REAR ENTRANCE AREA OF A WEAK
JET MAX ON THE SE SIDE OF THE UPPER TROUGH IS INTERACTING WITH
THE MODEST TRADE WIND CONVERGENCE TO ENHANCE SCATTERED
CONVECTION N OF THE ITCZ W OF 120W. LOOKING AHEAD THE
WEEKEND...THE BLOCKING RIDGE N OF HAWAII WILL BREAK DOWN AHEAD
OF AN APPROACHING CENTRAL PACIFIC TROUGH. THIS WILL ALLOW THE
SURFACE RIDGE THAT HAS BEGUN TO BUILD BEHIND THE CURRENT
WEAKENING W COAST COLD FRONT TO REMAIN IN PLACE N OF THE
AREA...MAINTAINING A BROAD SWATH OF FRESH TO STRONG TRADES FROM
10N TO 25N W OF 120W. SE CROSS-EQUATORIAL FLOW WILL CONVERGE
WITH THE NE TRADES TO KEEP CLUSTERS OF CONVECTION ACTIVE ALONG
THE ITCZ W OF 120W AS WELL. MEANWHILE ANOTHER PULSE OF NW SWELL
YIELDING COMBINED SEAS OF 10 FT AND GREATER WILL DOMINATE MOST
OF THE MARINE AREA W OF 115W TONIGHT AND SAT.
E OF 115W...THE MAIN WEATHER PHENOMENA REMAINS THE PERSISTENT
CENTRAL AMERICA GAP WINDS. HIGH RESOLUTION SCATTEROMETER DATA
SHOWED NELY WINDS OF 20 TO 25 KT THROUGH THE GULF OF
PAPAGAYO...AGAIN THIS MORNING...ENHANCED BY DRAINAGE EFFECTS...
WITH 20 KT WINDS NOTED OFF OF THE GULF OF FONSECA. FRESH TRADE
WINDS ARE PUSHING FROM THE SW CARIBBEAN S ACROSS PANAMA AS
WELL...INTO THE GULF OF PANAMA NEAR 20 KT...ENHANCING MODERATE
TO STRONG NOCTURNAL CONVECTION OFF THE COLOMBIAN COAST.
MEANWHILE...SCATTEROMETER DATA ALSO SHOWED NLY FLOW OF 20-25 KT
PERSISTING TO FLOW S OUT THROUGH THE GULF OF TEHUANTEPEC...BUT
IS FORECAST TO DIMINISH BRIEFLY THROUGH LATE SATURDAY BEFORE
POST FRONTAL WINDS ACROSS THE W GULF OF MEXICO FLOW DRAIN
THROUGH THE PASS AGAIN SUNDAY.


forecast by STRIPLING