Subject: Pacific-EN: Tropical Weather Discussion

From: SIU Weather Processor <[email-masked]>
Date: Wed, 12 Jan 2005 16:00:19 -0600

AXPZ20 KNHC 122200
TWDEP

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC WED JAN 12 2005

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2100 UTC.

..ITCZ...
INTERTROPICAL CONVERGENCE ZONE AXIS IS ALONG LINE 6N78W 4N100W
6N120W 7N130W 10N140W. SCATTERED MODERATE ISOLATED STRONG FROM
7.5N TO 12N W OF 132W.

..DISCUSSION...
N OF 20N...
RATHER AMPLIFIED MID/UPPER LEVEL RIDGE AXIS EXTENDS ALONG
15N131W NNEWD THROUGH 32N129W. RIDGE AXIS IS BETWEEN A LARGE
DEEP LAYERED LOW NW OF AREA NEAR 150W...AND ANOTHER MID/UPPER
LEVEL LOW INLAND OVER THE FOUR CORNERS AREA OF THE CONUS.
DESPITE THE RIDGING OVER AREA...SW FLOW IS VERY STRONG WITH A
MERGED POLAR-SUBTROPICAL JET STREAM OF 100-120 KT CUTTING
NNEWD ALONG 141W/142W AND CLIPPING THE FAR NW CORNER OF THE
AREA. DOWNSTREAM OF THE RIDGE AXIS AND SW OF THE WESTERN
UNITED STATES LOW...A STRONGER NW JET STREAM OF 135-145 KT
EXTENDS FROM OFF THE CALIFORNIA COAST ESEWD THROUGH NRN BAJA
CALIFORNIA TO 27N107W. OVER MAINLAND MEXICO...STRONG W-NW FLOW
IS DIGGING SW TO AREAS N OF 22N/23N...WITH MUCH LIGHTER WINDS
S OF 22N. AT THE SURFACE...A DYING COLD FRONT EXTENDS FROM SW
TEXAS ACROSS NW MEXICO AND THE SEA OF CORTEZ AND BAJA PENINSULA
ALONG 26N109W 23N115W 22N120W.  THE FRONT IS WEAKENING AND IS
EXPECTED TO DISSIPATE IN THE NEXT 6 HOURS.

MOST OF THE SIGNIFICANT CLOUDINESS OVER THE AREA IS W OF 130W
WHERE DEEP TROPICAL MOISTURE IS BEING PULLED NORTHWARD BY
STRONG UPPER LOW NEAR 150W. SCATTERED SHOWERS/THUNDERSTORM
ARE EMBEDDED WITHIN THE CLOUDINESS N OF 20N W OF 135W. THIS
AREA WILL BE THE FOCUS FOR SHOWERS/THUNDERSTORMS OVER THE NEXT
24 HOURS. AT THE SURFACE...A COLD FRONT IS ENTERING THE FAR NW
CORNER OF THE AREA. STRONG SE WINDS OF 25-35 KT AHEAD OF THE
FRONT HAVE PROMPTED THE ISSUANCE OF GALE WARNING FOR THE AREA N
OF 25N W OF 136W THIS AFTERNOON AND TONIGHT. REFER TO HIGH SEAS
FORECASTS UNDER AWIPS HEADER MIAHSFEP2...AMD WMO HEADER FZPN03
KNHC.

S OF 20N W OF 100W...
RELATIVELY TRANQUIL CONDITIONS PREVAIL AS A LARGE DEEP LAYERED
HIGH CONTROLS THE FLOW OVER MOST OF THIS AREA. THE RIDGE
MENTIONED IN SECTION ABOVE IS ANCHORED BY A HIGH CENTERED NEAR
9N130W. ANTICYCLONIC UPPER LEVEL FLOW AND ASSOCIATED MODERATE
TO LOCALLY STRONG SUBSIDENCE IS OBSERVED OVER MOST OF AREA. THE
HIGH IS PRODUCING AN AREA OF DIVERGENT FLOW OVER THE ITCZ W OF
130W. THIS IS AIDING IN THE DEVELOPMENT OF SCATTERED MODERATE TO
STRONG CONVECTION W OF 132W.

E OF 100W...
NEARLY STATIONARY MID/UPPER TROUGH CONTINUES OVER CENTRAL
AMERICA FROM HONDURAS AND EL SALVADOR SW TO NEAR 5N97W. SHARP
MOISTURE GRADIENT EXISTS ON EITHER SIDE OF THE TROUGH...WITH
WIDELY SCATTERED CONVECTION E OF THE TROUGH FROM THE ITCZ NORTH
TO COSTA RICA AND VERY DRY CONDITIONS W OF TROUGH. THIS GENERAL
PATTERN IS EXPECTED TO PERSIST...WITH ONLY CHANGE BEING A
MID/UPPER TROUGH MOVING ACROSS SE MEXICO DURING THE NEXT 24
HOURS. ONLY A SLIGHT INCREASE IN MOISTURE IS EXPECTED OVER SE
MEXICO WITH THE PASSAGE OF THE TROUGH.

LIGHT SURFACE WINDS ARE EXPECTED OVER THE GULF OF TEHUANTEPEC
REGION OVER THE NEXT 36 HOURS. THEREAFTER...AN INCREASE IN
NORTHERLY WINDS IS EXPECTED WITH WINDS BECOMING GALE FORCE IN
ABOUT 42-48 HOURS.

$$
COBB

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