[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 210533
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST FRI 21 JAN 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM
THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON
SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N8W 5N19W 3N31W 4N43W 4N52W.
NUMEROUS STRONG CONVECTION IS WITHIN 45 NM RADIUS OF EQ1W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
MOVING OFF THE COAST OF SOUTH AMERICA TO 13N BETWEEN 50W-60W.
WIDELY SCATTERED CLUSTERS OF SCATTERED MODERATE CONVECTION ARE
FROM 2N-5N BETWEEN 12W-18W AND FROM 1N-9N BETWEEN 27W-35W.

...DISCUSSION...

GULF OF MEXICO INTO THE W ATLANTIC...
PERSISTENT DEEP LAYERED TROUGH REMAINS OVER THE E UNITED
STATES...GULF OF MEXICO INTO THE W ATLC WITH THE MEAN AXIS ALONG
76W AND THE SHORTWAVE NOW MERGING WITH LONGWAVE TROUGH. THE
BROAD TROUGH CONTROLS MOST OF THE GULF AND THE W ATLC W OF 58W.
DRY AIR PRESENT IS IN THE MID/UPPER LEVELS WITH A NEW SURGE OF
COOLER AND EVEN DRIER AIR BEHIND THE COLD FRONT EXTENDING OVER
BERMUDA TO OVER THE CENTRAL CARIBBEAN NEAR 24N76W. BROKEN LOW
CLOUDS AND A FEW SHOWERS ARE BEHIND THE FRONT WITH A BAND OF
BROKEN/OVERCAST LOW CLOUDS WITH ISOLATED SHOWERS IN E GULF
WITHIN 60/75 NM OF LINE FROM 27N88W TO THE W COAST OF FLORIDA
NEAR 26N81W. COLD FRONT ASSOCIATED WITH THE LONGWAVE TROUGH
ENTERS THE AREA FROM A 1009 MB LOW NEAR 32N48W CONTINUING SSW
ALONG 24N51W TO JUST E OF THE LESSER ANTILLES NEAR 14N59W.
ISOLATED SHOWERS ARE WITHIN 120 NM OF FRONT N OF 24N. THIS FRONT
WILL CONTINUE TO WEAKEN AS THE LOW MOVES NORTHWARD. ALSO AT THE
SURFACE IS A 1022 MB HIGH LOCATED OVER THE CENTRAL ATLC NEAR
24N89W.

CARIBBEAN SEA...
THE MID/UPPER TROUGH COVERING THE GULF AND W ATLC HAS MOVED INTO
THE NW CARIBBEAN N OF 17N W OF 75W BRINGING THE DRIER/STABLE AIR
MASS AS FAR S AS JAMAICA. THIS TROUGH COUPLED WITH THE BROAD
MID/UPPER LEVEL RIDGE OVER THE TROPICAL ATLC INTO THE CENTRAL
ATLC ARE PRODUCING GENERALLY WESTERLY FLOW ACROSS THE CARIBBEAN.
DRY/STABLE AIR DOMINATES MOST OF THE CARIBBEAN WITH A BAND OF
MID LEVEL MOISTURE EXTENDING FROM THE YUCATAN PENINSULA S OF
JAMAICA TO OVER HISPANIOLA. BROKEN LOW LEVEL CLOUDS COVER THE E
CARIBBEAN WITH ONLY ISOLATED SHOWERS OVER THE VIRGIN ISLANDS AND
PUERTO RICO...REMNANTS OF THE LOW LEVEL MOISTURE REMAINING OVER
THE AREA AFTER THE MOST RECENT FRONTAL PASSAGE. THE RETURN FLOW
FROM THE SAME FRONTAL PASSAGE CONTINUES TO GENERATE OVERCAST LOW
CLOUDS WITH SCATTERED SHOWERS INLAND AND WITHIN 90 NM ALONG THE
COAST FROM W PANAMA TO S NICARAGUA.

CENTRAL/EASTERN ATLANTIC AND TROPICAL ATLANTIC...
BROAD HIGH AMPLITUDE RIDGE EXTENDS FROM DEEP IN THE TROPICS NEAR
EQ43W N TO 30N46W WITH ANTICYCLONIC FLOW COVERING THE AREA FROM
THE LESSER ANTILLES TO 28W. THIS FLOW IS IS ADVECTING TROPICAL
MOISTURE OVER SOUTH AMERICA INTO THE W TROPICAL ATLC ENHANCING
CONVECTION THERE AND THUS LEAVING A GOOD PORTION OF THE CENTRAL
ATLANTIC DRY. OVER THE NE ATLC IS A MID/UPPER LEVEL TROUGH IS N
OF THE CAPE VERDE ISLANDS W OF 28W. LIFT/DIVERGENCE OF THIS
TROUGH IS ENHANCING WIDELY SCATTERED MODERATE CONVECTION N OF
23N BETWEEN 20W-27W. A LOW/MID LEVEL CIRCULATION IS DEVELOPING
NEAR 24N26W IN ASSOCIATION WITH THE MID/UPPER LEVEL TROUGH. THE
SURFACE LOW THAT WAS PREVIOUSLY ASSOCIATED WITH A DEEP LAYERED
SYSTEM HAS LOST IS UPPER SUPPORT AND IS CENTERED NEAR 31N39W
WITH A WEAK SURFACE TROUGH EXTENDING SE TO 23N26W. ALSO AT THE
SURFACE IS A 1020 MB HIGH CENTERED IN THE CENTRAL ATLC NEAR
21N41W.

$$
WALLACE



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