[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 061753
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SUN JAN 06 2013

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1745 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS E TO W ALONG THE SOUTHERN COAST OF
AFRICA FROM 05E TO 08W...THEN CONTINUES W-SW TO 03N18W WHERE LOW
LEVEL WINDS INDICATE A TRANSITION TO AN ITCZ WHICH CONTINUES
W-SW TO THE COAST OF S AMERICA AT 01S48W. SCATTERED MODERATE
ISOLATED STRONG CONVECTION IS NOTED ABOUT 240 NM S OF THE
MONSOON TROUGH...ROUGHLY WITHIN 30 NM EITHER SIDE OF A LINE FROM
04N07E TO 01N01E TO 02N14W...AND A LINE FROM 02N23W TO 03N31W TO
04N36W TO 02N50W. SIMILAR CONVECTION IS NOTED ALONG THE EQUATOR
BETWEEN 28W AND 35W.

...DISCUSSION...

GULF OF MEXICO...

AN UPPER LEVEL SHORTWAVE TROUGH IS ADVANCING EASTWARD ACROSS
EASTERN N AMERICA WITH SOUTHWESTERLY UPPER FLOW PRECEDING THE
TROUGH ACROSS THE ENTIRE GULF OF MEXICO. A STATIONARY SURFACE
FRONT EXTENDS W ACROSS FLORIDA AND THE GULF OF MEXICO ALONG 28N
TO 91W...THEN TURNS S INTO A 1017 MB FRONTAL WAVE LOW AT
25N93W...WITH A COLD FRONT EXTENDING S FROM THE LOW TO THE
EASTERN BAY OF CAMPECHE. BROKEN TO OVERCAST LOW TO MID LEVEL
CLOUDS IS OBSERVED NW OF A LINE FROM THE FLORIDA BIG BEND TO THE
BAY OF CAMPECHE. UPPER DIFFLUENCE IS ENHANCING SCATTERED
MODERATE ISOLATED STRONG CONVECTION...WITH FREQUENT LIGHTNING...
OVER THE CENTRAL GULF WATERS WITHIN 180 NM OF 26N89W. NORTHERLY
WINDS W OF THE SURFACE LOW AND COLD FRONT ARE AT 20 TO 30 KT
WITH THIS NORTHERLY FLOW CONTINUING S THROUGH THE CHIVELA PASS
INTO THE GULF OF TEHUANTEPEC...WHERE THE NORTHERLY FLOW IS AT
GALE FORCE. THE LOW IS EXPECTED TO LIFT NE THIS AFTERNOON AND
DISSIPATE TONIGHT WITH REMNANTS OF THE LIFTING N THROUGH THROUGH
MON NIGHT.

CARIBBEAN SEA...

AN UPPER LEVEL ANTICYCLONE IS OVER THE SUBTROPICAL ATLANTIC JUST
N OF PUERTO RICA WITH AN UPPER RIDGE EXTENDING W-SW ACROSS THE
NORTHERN CARIBBEAN TO A CREST OVER THE GULF OF HONDURAS.
SCATTERED SHOWERS AND A FEW THUNDERSTORMS ARE NOTED OVER THE
FAR WESTERN GULF OF HONDURAS AND BELIZE WITH THE RESULTANT DENSE
DEBRIS MOISTURE ADVECTED N ALONG THE PERIPHERY OF THE UPPER
RIDGE ACROSS THE YUCATAN CHANNEL AND WESTERN CUBA. ADDITIONAL
UPPER MOISTURE...THOUGH NOT VERY DENSE...IS INDICATED OVER THE
REMAINDER OF THE NW CARIBBEAN CONTINUING NE ACROSS CUBA AND THE
CENTRAL BAHAMAS. OTHERWISE VERY DRY UPPER AIR ACCOMPANIES THE
UPPER RIDGE...AND IS SUPPRESSING CONVECTION ACROSS THE CARIBBEAN
SEA.

AT THE LOW LEVELS FRESH TO STRONG EASTERLY TRADES ARE ADVECTING
FAIR WEATHER CUMULUS ACROSS THE CARIBBEAN WITH SHOWERS ENHANCED
OVER THE LARGER ISLANDS WITH ELEVATED TERRAIN. THESE EASTERLIES
ARE AT MINIMAL GALE STRENGTH IN THE AREA FROM 11N TO 13N BETWEEN
73W AND 78W WITH SEAS 9 TO 14 FT...BUT EXPECTED TO DIMINISH
BELOW GALE STRENGTH EARLY THIS AFTERNOON.

ATLANTIC OCEAN...

A LONGWAVE TROUGH DOMINATES THE CENTRAL N ATLANTIC WHILE
SHORTWAVE UPPER RIDGES ARE NOTED OVER THE WESTERN AND EASTERN N
ATLANTIC. THE WESTERN RIDGE ORIGINATES FROM AN UPPER ANTICYCLONE
CENTERED JUST N OF PUERTO RICO. THIN UPPER MOISTURE IS STREAMING
NE ACROSS THE BAHAMAS WHILE DENSE UPPER MOISTURE IS NOTED OVER
THE NW PORTION OF THE DISCUSSION AREA. A SURFACE COLD FRONT
STRETCHES FROM 31N35W TO 26N56W WHERE THE BOUNDARY BECOMES
NEARLY STATIONARY TO 28N65W...WHERE THE FRONT HAS BEGUN MOVING N
AS A WARM FRONT TO ACROSS FLORIDA ALONG 28N. LOCALLY BROKEN LOW
AND MID LEVEL CLOUDS...WITH EMBEDDED SHOWERS...ARE OBSERVED
WITHIN 90 NM N OF THE SURFACE FRONT WHILE FAIR WEATHER CUMULUS
AND STRATOCUMULUS CLOUDS ARE OBSERVED ACROSS THE REMAINDER OF
THE AREA W OF 35W WITH THESE CLOUDS MOVING W IN THE FRESH
EASTERLY WINDS WELL TO THE S OF THE PREVIOUSLY MENTIONED SURFACE
FRONT. SURFACE HIGH PRESSURE AT 1026 MB IS CENTERED N OF THE
FRONT NEAR 31N58W AND IS EXPECTED TO SHIFT E ALONG 31N OVER THE
NEXT 24 HOURS WITH A RIDGE EXTENDING W TO NEAR 28N78W. THE RIDGE
WILL RETRACT E ALLOWING A COLD FRONT TO MOVE TO ENTER THE NW
WATERS TONIGHT WHILE LIFTING REMNANTS OF THE CURRENT FRONT N.

AN UPPER TROUGH EXTENDS INTO THE AREA ALONG 32N35W TO 21N44W
WITH DENSE UPPER MOISTURE OBSERVED UNDER A SHORTWAVE RIDGE E OF
THE E OF THIS TROUGH TO 18W. A SECOND UPPER TROUGH EXTENDS SW
ACROSS NW AFRICA ALONG 30N03E TO 20N17W CONTINUING SW TO BASE
NEAR 07N32W AND IS ACCOMPANIED BY DRY UPPER AIR WITHIN 120 NM OF
THE TROUGH AXIS. A BROAD RIDGE IS NOTED OVER THE FAR EASTERN
TROPICAL ATLANTIC AND IS ADVECTING DENSE DEBRIS MOISTURE NE
ACROSS WITHIN 540 NM EITHER SIDE OF A LINE FROM 09N14W TO TO
BEYOND 21N10E. DRY UPPER AIR IS NOTED OVER THE TROPICAL ATLANTIC
FROM 10N TO 22N BETWEEN 18W AND 28W WITH MOSTLY CLEAR SKIES
INDICATED WHILE LOCALLY BROKEN STRATOCUMULUS IS STREAMING SW
WITHIN 150 NM EITHER SIDE OF A LINE FROM 22N28W TO 10N36W.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
NELSON








This weather bulletin was brought to you by:
www.nashvilleweather.net