AXNT20 KNHC 202355
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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.
...ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 10N12W 6N25W 7N44W 7N60W. WIDELY
SCATTERED MODERATE CONVECTION IS FROM 3N-7N BETWEEN 24W-32W.
SIMILAR CONVECTION IS FOCUSED ALONG A SURFACE TROUGH EMBEDDED
WITHIN THE ITCZ FROM 12N42W TO 5N45W. THE CONVECTION COVERS AN
AREA FROM 7N-10N BETWEEN 39W-48W.
...DISCUSSION...
GULF OF MEXICO...
AS OF 2100 UTC...A 1010 MB LOW IS CENTERED OFF THE COAST OF
TEXAS NEAR 27N95W. A WARM FRONT EXTENDS E FROM THE LOW TO
26N90W. A SURFACE TROUGH ALSO EXTENDS S FROM THE LOW CENTER TO
24N98W. 25 KT WINDS ARE NOTED OVER THE NW GULF OF MEXICO IN
VICINITY OF THE LOW. WIDELY SCATTERED MODERATE CONVECTION IS
FROM 25N-30N BETWEEN 90W-94W. IN THE UPPER LEVELS...ZONAL FLOW
COVERS THE GULF. SIGNIFICANT UPPER LEVEL MOISTURE IS OVER THE N
GULF N OF 26N. STRONG SUBSIDENCE COVERS THE S GULF. EXPECT THE
SURFACE LOW TO MOVE TO THE MISSISSIPPI COAST IN 24 HOURS WITH A
TRAILING COLD FRONT EXTENDING S TO THE YUCATAN PENINSULA AND A
WARM FRONT OVER THE FLORIDA PANHANDLE. EXPECT 15-20 KT N WINDS W
OF THE COLD FRONT AND 10 KT S WINDS E OF THE COLD FRONT. ALSO
EXPECT CONVECTION TO BE ALONG THE WARM FRONT OVER N FLORIDA AND
E OF THE COLD FRONT OVER THE S GULF OF MEXICO.
CARIBBEAN SEA...
MODERATE TO FRESH TRADEWINDS DOMINATES THE BASIN. A 1004 MB LOW
IS CENTERED INLAND OVER N COLOMBIA NEAR 8N75W. WIDELY SCATTERED
MODERATE CONVECTION IS FROM 4N-9N BETWEEN 75W-79W. PATCHES OF
BROKEN TO OVERCAST LOW CLOUDS DOTS THE CARIBBEAN AND CENTRAL
AMERICA NAMELY OVER THE WINDWARD ISLANDS S OF 14N AND E OF
62W...OVER PUERTO RICO...HISPANIOLA...AND THE NW CARIBBEAN FROM
17N-22N BETWEEN 82W-90W. SIMILAR SHOWERS ARE OVER THE SW
CARIBBEAN S OF 11N. IN THE UPPER LEVELS...A BROAD RIDGE IS
PRODUCING ZONAL FLOW OVER THE ENTIRE CARIBBEAN. DRY AIR AND
SUBSIDENCE COVERS THE ENTIRE AREA WITH UPPER LEVEL MOISTURE
REMAINING ONLY OVER N COLOMBIA. EXPECT...SHOWERS/THUNDERSTORMS
TO CONTINUE OVER THE SW CARIBBEAN OVER THE NEXT 24 HOURS. ALSO
EXPECT...SIMILAR CONVECTION OVER THE WINDWARD ISLANDS.
ATLANTIC OCEAN...
A 1012 MB LOW IS OVER THE W ATLANTIC NEAR 32N75W. A SURFACE
TROUGH EXTENDS S FROM THE LOW TO THE CENTRAL BAHAMAS NEAR
25N75W. SCATTERED SHOWERS ARE WITHIN 180 NM OF THE TROUGH AXIS.
ANOTHER SURFACE TROUGH IS OVER THE W ATLANTIC N OF PUERTO RICO
ALONG 25N64W 19N66W. SCATTERED SHOWERS ARE WITHIN 240 NM E OF
THIS TROUGH AXIS. A LONG STATIONARY FRONT IS OVER THE ATLANTIC
ALONG 32N26W 29N33W TO AN EMBEDDED 1015 MB LOW NEAR 27N51W TO
30N64W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 25N-28N
BETWEEN 46W-52W...AND FROM 28N-31N BETWEEN 59W-68W. FURTHER E
...A RIDGE AXIS EXTENDS FROM S PORTUGAL TO SW OF THE CANARY
ISLANDS NEAR 25N27W. EXPECT THE LOW OVER THE W ATLANTIC TO MOVE
NE OVER THE NEXT 24 HOURS LEAVING THE TAIL END OF A SURFACE
TROUGH OVER THE AREA S OF 30N. ALSO EXPECT MORE CONVECTION OVER
THE CENTRAL ATLANTIC FROM 20N-32N BETWEEN 40W-55W DUE TO THE
CENTRAL ATLANTIC LOW OVER THE NEXT 24 HOURS.


forecast by FORMOSA
updated at 705 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