[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201722
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT JAN 20 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...
CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...
NORTHEASTERN SECTIONS OF SOUTH AMERICA...AND THE 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.

...THE ITCZ...
AXIS CENTERED ALONG 8N13W 5N20W 3N30W 2N40W CROSSING THE EQUATOR
AT 46W. ISOLATED SHOWERS/TSTMS NOTED WITHIN 60 NM OF THE AXIS
BETWEEN 27W-31W. OVERALL THOUGH...VERY LITTLE IN THE WAY OF DEEP
CONVECTION EXISTS WITHIN SEVERAL HUNDRED NM OF THE AXIS.

...DISCUSSION...
THE GULF OF MEXICO...
SUBTROPICAL JET CONTINUES TO SPREAD MID TO UPPER MOISTURE FROM
THE NE PAC THROUGH THE DEEP SOUTH...CLIPPING THE NRN GULF
WATERS. EXTREMELY DRY MID TO UPPER AIR IS SEEN IN WV IMAGERY SE
OF A LINE FROM VERACRUZ MEXICO TO TAMPA BAY FLORIDA. OVERALL THE
MID TO UPPER PATTERN REMAINS DOMINATED BY RIDGING...THOUGH A
WEAK UPPER TROUGH IS EMBEDDED IN THE ANTICYCLONIC FLOW WITH THE
AXIS EXTENDING NNE FROM THE ISTHMUS OF TEHUANTEPEC TO NEAR
25N90W. SFC FRONTAL PATTERN REMAINS A LITTLE DIFFICULT TO
ANALYZE. AS OF 1500 UTC...A WEAK 1017 MB LOW IS LOCATED OFF
OF SE TEXAS THAT HAS A WARM FRONT EXTENDING E TO NEAR 27N87W. A
DYING STATIONARY FRONT THEN EXTENDS FROM THIS POINT TO NEAR
NAPLES FLORIDA. A LINGERING STATIONARY FRONT ALSO EXISTS S OF
THE SFC LOW TO THE CENTRAL BAY OF CAMPECHE. THE WRN GULF PORTION
OF THE FRONT IS MUCH EASIER TO ANALYZE...IN ADDITION TO THE WIND
SHIFT THERE IS A 26F DEG TEMP/22F DEG DEWPOINT GRADIENT BETWEEN
BROWNSVILLE TX AND BUOY 42002. THERE IS ALSO QUITE A DEWPOINT
GRADIENT ACROSS THE FLORIDA PENINSULA BUT A WEAK SFC RIDGE AXIS
IS EVIDENT WHICH HAS MADE THE FRONTAL PLACEMENT DIFFICULT.
BROKEN TO OVERCAST LOW CLOUD/LIGHT RAIN STILL EXISTS BEHIND THE
FRONT W OF 85W. FEW TO SCATTERED LOW CLOUDS NOTED AHEAD OF THE
FRONT. A CONVERGENT LINE WITH SHOWERS IS SEEN OFF SE FLORIDA AND
IN THE STRAITS OF FLORIDA. SFC LOW OFF SE TX EXPECTED TO MOVE NE
TOWARDS NW MISSISSIPPI BY TOMORROW MORNING. SFC HIGH PRESSURE
N/NE OF THE AREA EXPECTED TO TAKE OVER THE PATTERN ON SUN
EXCEPT FAR NW PORTION WHERE A QUASI STATIONARY FRONTAL
BOUNDARY LINGERS. WINDS WILL VEER SE 10-20 KT AHEAD OF THIS
BOUNDARY WITH LIGHTER NE WINDS BEHIND THE FRONT.

THE CARIBBEAN SEA...
DRY MID TO UPPER AIR IS ROTATING AROUND AN UPPER RIDGE OVER THE
CARIBBEAN THIS AFTERNOON. THIS CONTINUES TO SUPPRESS CONVECTION
ACROSS THE AREA. AT THE SFC...15-20 KT TRADES CONTINUE S OF HIGH
PRES...EXCEPT 25-30KT NEAR THE COLOMBIAN COAST. THIS FETCH
CONTINUES TO PRODUCE MODERATE TO STRONG SURF ALONG THE CARIBBEAN
COAST OF COSTA RICA AND PANAMA. THE TRADES ARE ADVECTING TYPICAL
PATCHES OF LOW LEVEL MOISTURE WITH EMBEDDED SHOWERS WWD. THE
MOST SIGNIFICANT AREA OF MOISTURE/SHOWERS IS JUST OFFSHORE THE
NICARAGUAN COAST AT THE MOMENT. GFS LOW TO MID LEVEL MOISTURE
FIELDS ARE PICKING UP ON THIS AND SUGGEST THE AREA WILL GAIN
SOME STEAM AS IT PUSHES INTO NICARAGUA TONIGHT. MODERATE TO
FRESH TRADES CONTINUE THROUGH MON.

THE ATLANTIC OCEAN...
UPPER RIDGING OVER THE SW N ATLC CONTINUES TO ADVECT A BAND OF
MOISTURE/HIGH CLOUDS EWD OFF THE SE U.S. COAST INTO THE W AND
CENTRAL ATLC. VERY DRY UPPER AIR...HOWEVER...IS SW OF A LINE
FROM THE NW BAHAMAS TO LEEWARD ISLANDS. QUASI STATIONARY SFC
FRONT ENTERS THE AREA AT 32N58W AND CONTINUES WSW TO SE FLORIDA.
THERE IS A RAGGED LOW CLOUD LINE ASSOCIATED WITH THIS FRONT...IN
ADDITION TO NOTABLE SPEED CONFLUENCE AS SHOWN IN THIS MORNINGS
QUIKSCAT PASS. A WEAK 1019 MB SFC HIGH IS SE OF THE FRONT NEAR
25N58W. THIS HIGH EXPECTED TO GET TAKEN OVER BY STRONGER HIGH
PRES RIDGING SE OFF THE MID ATLC COAST BEHIND THE FRONT THROUGH
SUN. AN UPPER TROUGH EXTENDS S THROUGH THE CENTRAL ATLC WATERS
ALONG 40W...WITH A 1012 MB SFC REFLECTION NEAR 27N44W. THERE ARE
ACTUALLY 4 LOW LEVEL SWIRLS NOTED FROM 20N-29N BETWEEN
40W-57W...BUT FOR THE SAKE OF CONTINUITY AND THE FACT THIS IS A
SYNOPTIC MAP...HAVE OPTED TO CONTINUE TRACKING THE MOST
SIGNIFICANT OF THESE. REGARDLESS...THE PARENT BROAD LOW IS
EXPECTED TO GET ABSORBED INTO THE MUCH STRONGER STORM TO DEVELOP
SE OF THE CANADIAN MARITIMES LATE TONIGHT NEAR 40N52W. UPPER
RIDGING IS TAKING OVER THE E ATLC...AS THE UPPER LOW WE'VE BEEN
TRACKING JUST N OF THE CANARY ISLANDS MOVES OUT OF THE AREA.
UPPER WLY FLOW WITH THE RIDGE IS ADVECTING A PLUME OF MOISTURE
WITH POSSIBLE SHOWERS EWARD FROM 7N-22N BETWEEN 40W AND AFRICA.
LIGHT TO MODERATE E TO NE SFC WINDS ARE BEING FELT IN THE E ATLC
AS WELL...S OF HIGH PRESSURE RIDGING FROM SW EUROPE.

$$
WILLIS



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