Atlantic Tropical Weather Discussion

000
AXNT20 KNHC 061756
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT OCT 06 2012

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 
1715 UTC.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 09N24W TO 17N26W MOVING W AT 10-15 
KT. THE WAVE IS EMBEDDED WITHIN A LOW-LEVEL MONSOON GYRE 
CENTERED AT THE SOUTHERN EXTENT OF THE WAVE AXIS NEAR 09N24W AND 
ALSO COINCIDES WITH BROAD 700 MB TROUGHING BETWEEN 20W-30W IN AN 
AREA WEST OF THE CAPE VERDE ISLANDS. WHILE MOST DEEP CONVECTION 
IS S OF 10N ASSOCIATED WITH THE MONSOON TROUGH...ISOLATED 
MODERATE CONVECTION IS FROM 11N-14N BETWEEN 24W-28W.

TROPICAL WAVE EXTENDS FROM 12N68W TO 18N67W MOVING W AT 10-15 
KT. THE WAVE IS LARGELY AN EXTENSION OF LOW-LEVEL TROUGHING FROM 
A 1008 MB SURFACE LOW CENTERED NORTH OF THE MONA PASSAGE NEAR 
22N67W COMBINED WITH ENERGY THAT HAS ROTATED AROUND THE 
PERIPHERY OF A MID-LEVEL RIDGE ANCHORED OVER THE SW NORTH ATLC 
DURING THE PAST WEEK. NO SIGNIFICANT CONVECTION IS NOTED ON 
SATELLITE IMAGERY AT THIS TIME.

TROPICAL WAVE EXTENDS FROM 11N77W TO 18N80W MOVING W AT 10-15 
KT. THE WAVE IS EMBEDDED WITHIN AN AREA OF DEEP LAYER MOISTURE 
ACROSS THE SW CARIBBEAN SEA PRIMARILY S OF 14N BETWEEN 75W-83W 
AS NOTED ON TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE 
CONVECTION IS FROM 10N-14N BETWEEN 77W-83W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 07N12W TO 
05N18W TO 09N24W TO 11N34W TO 09N40W. WIDELY SCATTERED MODERATE 
CONVECTION IS FROM 02N-05N BETWEEN 07W-18W...AND FROM 07N-11N 
BETWEEN 33W-40W. SCATTERED MODERATE CONVECTION IS FROM 04N-11N 
BETWEEN 22W-31W.

...DISCUSSION...

GULF OF MEXICO...
BROAD MIDDLE TO UPPER LEVEL TROUGHING IS NOTED ON WATER VAPOR 
IMAGERY OVER MUCH OF THE CENTRAL AND EASTERN CONUS WITH A VERY 
WEAK TROUGH AXIS EXTENDING FROM OVER THE EASTERN SEABOARD NEAR 
33N79W SOUTHWESTWARD TO OVER THE WESTERN GULF NEAR 25N93W. WEST 
TO SOUTHWESTERLY FLOW ALOFT DOMINATES WITH MOISTURE ADVECTING 
FROM THE SW GULF NORTHEASTWARD OVER THE EASTERN GULF...FLORIDA 
PENINSULA...AND INTO THE SW NORTH ATLC. WHILE NO DISTINCT 
SURFACE FEATURE OR FRONT IS PRESENT...WIDELY SCATTERED SHOWERS 
AND ISOLATED TSTMS ARE OCCURRING WITHIN 150 NM EITHER SIDE OF A 
LINE FROM 18N95W TO 28N81W MAINLY DUE TO SUFFICIENT MIDDLE TO 
UPPER LEVEL LIFT. WELL TO THE NORTHWEST OF THIS MOISTURE...A 
COLD FRONT IS ANALYZED FROM THE APPALACHIANS TO SOUTHERN 
MISSISSIPPI AND TO THE TEXAS GULF COAST NEAR GALVESTON. THE 
FRONT LACKS ANY SIGNIFICANT MOISTURE AND PRECIPITATION AS A 
DRIER AIRMASS FOLLOWS ALONG WITH A STRONGER SURFACE RIDGE. THE 
RIDGING IS FORECAST TO BUILD IN ACROSS MUCH OF THE GULF THROUGH 
MONDAY. AS A RESULT...NORTHEASTERLY WINDS ARE EXPECTED TO 
PREVAIL FOR THE DURATION OF THE WEEKEND WITH AREAS OF 15 TO 20 
KT EXPECTED OVER THE NW GULF WITH THE PASSAGE OF THE FRONT.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER 
HONDURAS NEAR 16N87W AND IS PROVIDING AN OVERALL SUBSIDENT 
ENVIRONMENT ACROSS THE WESTERN CARIBBEAN THIS AFTERNOON. 
NORTHERLY FLOW ALOFT ON THE EASTERN PERIPHERY OF THIS UPPER 
LEVEL RIDGE CONTINUES TO SUSTAIN DRY AIR OVER THE NW CARIBBEAN N 
OF 14N W OF 74W EVEN WITH THE PRESENCE OF A TROPICAL WAVE ALONG 
80W. ONLY ISOLATED SHOWERS AND TSTMS ARE NOTED ON SATELLITE 
IMAGERY IN THE GULF OF HONDURAS AND ALONG COASTAL BELIZE. SOUTH 
OF 14N OVER THE SW CARIBBEAN...THE BASE OF AN UPPER LEVEL TROUGH 
ALONG WITH LOW-LEVEL MOISTURE CONVERGENCE IS GENERATING 
SCATTERED SHOWERS AND TSTMS FROM 10N-14N BETWEEN 77W-83W. 
FURTHER SUPPORTING THIS CONVECTION IS THE TROPICAL WAVE MOVING 
WESTWARD AND THE CLOSE PROXIMITY OF THE MONSOON TROUGH ANALYZED 
FROM COSTA RICA EASTWARD ALONG 10N TO THE TROPICAL WAVE AXIS. 
THE AFOREMENTIONED BASE TO THE UPPER LEVEL TROUGH IS PART OF A 
LARGER MIDDLE TO UPPER LEVEL LOW CENTERED NE OF THE LEEWARD 
ISLANDS NEAR 21N60W. EMBEDDED WITHIN THE INFLUENCE OF THIS UPPER 
LEVEL LOW AND TROUGHING ARE A 1008 MB LOW CENTERED NORTH OF THE 
MONA PASSAGE NEAR 22N67W AND A TROPICAL WAVE ALONG 68W. MOST OF 
THE MORE INTENSE CONVECTIVE ACTIVITY REMAINS N OF 20N...HOWEVER 
A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING ALONG THE 
NORTHERN COAST OF HISPANIOLA AND IN THE ADJACENT COASTAL WATERS 
OF SOUTHERN HAITI FROM 16N-18N BETWEEN 71W-74W.

ATLANTIC OCEAN...
SURFACE RIDGING IS LOCATED OVER NORTHWEST PORTIONS OF THE SW 
NORTH ATLC...HOWEVER A VERY BROAD UPPER LEVEL TROUGH IS OVER THE 
EASTERN CONUS AND EASTERN SEABOARD WITH A TROUGH AXIS EXTENDING 
FROM 33N77W SW INTO THE CENTRAL AND WESTERN GULF OF MEXICO. THIS 
TROUGH CONTINUES TO ADVECT MIDDLE TO UPPER LEVEL MOISTURE 
NORTHEASTWARD FROM THE SOUTHERN GULF OF MEXICO OVER THE FLORIDA 
PENINSULA TO BEYOND 32N75W AND GENERATE SCATTERED SHOWERS AND 
WIDELY SCATTERED TSTMS FROM 28N-33N BETWEEN 74W-80W. FARTHER SE 
OVER THE REMAINDER OF THE SW NORTH ATLC...AN UPPER LEVEL 
SHORTWAVE TROUGH AXIS IS ALONG 74W AND IS EMBEDDED WITHIN THE 
LARGER-SCALE SYNOPTIC FLOW OF A BROAD MIDDLE TO UPPER LEVEL LOW 
CENTERED NE OF THE EASTERN CARIBBEAN SEA NEAR 21N60W. THE 
RESULTANT FEATURE AT THE SURFACE IS A 1008 MB LOW CENTERED NEAR 
22N67W THAT CONTINUES TO PRODUCE SCATTERED SHOWERS AND TSTMS IN 
THE VICINITY OF THE SURFACE LOW AND ALSO IN AN AREA OF MAXIMUM 
UPPER LEVEL DIFFLUENCE FROM 19N-27N BETWEEN 62W-73W WITH THE 
STRONGEST CONVECTION LOCATED WITHIN THE NW QUADRANT. ELSEWHERE 
ACROSS THE EASTERN AND CENTRAL ATLC...AN UPPER LEVEL LOW 
CENTERED NORTH OF THE DISCUSSION AREA NEAR 41N33W SUPPORTS A 
COLD FRONT ANALYZED ALONG 32N28W TO 24N40W TO 25N53W WHERE IT 
BECOMES STATIONARY TO 26N58W TO 24N67W...NORTH AND VERY NEAR THE 
1008 MB LOW. ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 120 
NM EAST OF THE COLD FRONT AND WITHIN 90 NM EITHER SIDE OF THE 
STATIONARY FRONT BETWEEN 55W-65W.

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

$$
HUFFMAN