[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 281804
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT SEP 28 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
1715 UTC.

...SPECIAL FEATURES...

A 1011 MB ATLANTIC OCEAN LOW PRESSURE PRESSURE CENTER IS NEAR
23N51W. THIS POSITION IS ABOUT 750 NM TO THE EAST-NORTHEAST OF
THE NORTHEASTERN CORNER OF THE CARIBBEAN SEA. IT IS POSSIBLE
THAT A TROPICAL DEPRESSION MAY FORM THIS SYSTEM DURING THE NEXT
DAY OR TWO AS THE LOW MOVES NORTHWARD AND THEN NORTHEASTWARD 9
TO 13 KNOTS. THIS SYSTEM HAS A HIGH CHANCE OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS. ENVIRONMENTAL
CONDITIONS APPEAR TO BE MARGINALLY CONDUCIVE FOR DEVELOPMENT
AFTER 48 HOURS. THE SYSTEM HAS A HIGH CHANCE 70 PERCENT OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 5 DAYS. ADDITIONAL
INFORMATION ON THIS SYSTEM IS FOUND IN HIGH SEAS FORECASTS THAT
ARE ISSUED BY THE NATIONAL WEATHER SERVICE. CONVECTIVE
PRECIPITATION...NUMEROUS STRONG FROM 24N TO 26N BETWEEN 48W AND
51W.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 23W TO THE SOUTH OF 17N
MOVING WESTWARD 15 KNOTS. CONVECTIVE PRECIPITATION...NUMEROUS
STRONG FROM 13N TO 16N BETWEEN 21W AND 22W. SCATTERED MODERATE
TO ISOLATED STRONG ELSEWHERE FROM 7N TO 15N BETWEEN 21W AND 30W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 56W TO THE SOUTH OF
18N...MOVING WESTWARD 15 KNOTS. NO SIGNIFICANT DEEP CONVECTIVE
PRECIPITATION IS APPARENT.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 63W/64W TO THE SOUTH OF
17N MOVING WESTWARD 10 TO 15 KNOTS. IT IS MOVING THROUGH THE
AREA OF A MIDDLE LEVEL TO UPPER LEVEL TROUGH THAT EXTENDS FROM
AN ATLANTIC OCEAN 27N56W CYCLONIC CIRCULATION CENTER...TO 22N57W
17N60W TO 14N62W AND 10N63W IN NORTHEASTERN VENEZUELA. THE
TROPICAL WAVE ALSO IS SURROUNDED BY COMPARATIVELY DRIER AIR IN
SUBSIDENCE IN WATER VAPOR IMAGERY. RAINSHOWERS ARE POSSIBLE IN
THE CARIBBEAN SEA AND IN THE ATLANTIC OCEAN FROM 10N TO 15N
BETWEEN 58W AND 65W...MOST LIKELY AS A RESULT OF THE MIDDLE
LEVEL TO UPPER LEVEL TROUGH.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH PASSES THROUGH THE COASTAL AREAS OF GAMBIA TO
10N24W AND 9N29W. THE ITCZ CONTINUES FROM 9N29W 7N35W 4N39W AND
3N43W. CONVECTIVE PRECIPITATION...NUMEROUS STRONG FROM 4N TO 6N
BETWEEN 32W AND 33W...FROM 7N TO 9N BETWEEN 45W AND 47W...FROM
6N TO 7N BETWEEN 49W AND 51W...AND FROM 6N TO 7N BETWEEN 53W AND
55W. WIDELY SCATTERED MODERATE TO ISOLATED STRONG ELSEWHERE FROM
3N TO 10N BETWEEN 30W AND 56W.

...DISCUSSION...

FROM THE CENTRAL ATLANTIC OCEAN...INTO THE WESTERN ATLANTIC
OCEAN...ACROSS THE BAHAMAS AND INTO THE GULF OF MEXICO...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH EXTENDS FROM A 34N74W
CYCLONIC CIRCULATION CENTER TO 27N76W TO CUBA NEAR 23N80W TO
19N80W AND THE COAST OF HONDURAS NEAR 16N85W. A COLD FRONT
PASSES THROUGH 32N51W TO 30N56W. THE FRONT BECOMES STATIONARY
FROM 30N56W TO 29N64W...AND TO A 1008 MB LOW PRESSURE CENTER
THAT IS NEAR 29N70W. A COLD FRONT EXTENDS FROM THE 1008 MB LOW
CENTER TO 26N70W...TO 23N74W IN THE BAHAMAS...TO 23N80W ALONG
THE COAST OF CUBA. THE FRONT BECOMES STATIONARY AGAIN FROM
23N80W TO 23N89W. A SHEAR AXIS/REMNANT CLOUD LINE EXTENDS FROM
23N89W TO 25N93W AND TO THE CENTRAL TEXAS GULF COAST NEAR
29N96W. CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO
ISOLATED STRONG IN THE ATLANTIC OCEAN IN THE AREA THAT IS
BOUNDED BY THE POINTS FROM 22N77W TO 24N66W TO 27N57W 30N59W
33N63W 22N77W. ISOLATED MODERATE ELSEWHERE IN THE ATLANTIC OCEAN
TO THE NORTH OF 20N TO THE WEST OF 60W. RAINSHOWERS ARE POSSIBLE
IN THE GULF OF MEXICO WITHIN 30 TO 60 NM ON EITHER SIDE OF
25N82W 27N86W 30N87W...AND WITHIN 30 NM TO 60 NM ON EITHER SIDE
OF THE GULF OF MEXICO STATIONARY FRONT/SHEAR AXIS. ONE INCH OF
RAIN WAS RECORDED AT VERACRUZ IN MEXICO DURING THE LAST 24 HOURS
ENDING AT 28/1200 UTC...ACCORDING TO THE MIATPTPAN BULLETIN.
FAIR SKIES COVER THE REST OF THE GULF OF MEXICO.

FROM CUBA INTO THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA
INCLUDING HISPANIOLA AND A 63W/64W TROPICAL WAVE...

UPPER LEVEL SOUTHWESTERLY WIND FLOW IS MOVING ACROSS HISPANIOLA.
COMPARATIVELY DRIER AIR IN SUBSIDENCE IN WATER VAPOR IMAGERY
COVERS THE AREA. NO SIGNIFICANT DEEP CONVECTIVE PRECIPITATION IS
APPARENT.

A MIDDLE LEVEL TO UPPER LEVEL SHORTWAVE TROUGH EXTENDS FROM CUBA
NEAR 23N80W TO 16N85W ALONG THE COAST OF HONDURAS. THE CYCLONIC
WIND FLOW COVERS THE CARIBBEAN SEA FROM 16N TO CUBA BETWEEN THE
WINDWARD PASSAGE AND THE YUCATAN CHANNEL.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 63W/64W TO THE SOUTH OF
17N MOVING WESTWARD 10 TO 15 KNOTS. THE TROPICAL WAVE IS MOVING
THROUGH THE AREA OF A MIDDLE LEVEL TO UPPER LEVEL 27N56W-TO-
10N63W TROUGH. THE TROPICAL WAVE ALSO IS SURROUNDED BY
COMPARATIVELY DRIER AIR IN SUBSIDENCE IN WATER VAPOR IMAGERY.

THE GFS FORECAST FOR 700 MB SHOWS THAT AN EAST-TO-WEST ORIENTED
RIDGE WILL COVER THE AREA. THE 500 MB GFS MODEL SHOWS THAT
HISPANIOLA WILL BE ON THE EASTERN SIDE OF A TROUGH FOR THE
ENTIRE 48 HOURS OF THE FORECAST PERIOD. THE GFS FORECAST FOR 250
MB SHOWS THAT A TROUGH WILL CUT ACROSS THE AREA FOR MUCH OF THE
FIRST 24 HOURS. THE TROUGH WILL MOVE NORTHEASTWARD AND OUT OF
THE AREA. THE TROUGH WILL BE REPLACED BY A NORTHEAST-TO-
SOUTHWEST ORIENTED RIDGE. HISPANIOLA WILL BE ON THE NORTHWESTERN
SIDE OF THE RIDGE.

ANTICYCLONIC WIND FLOW WILL COVER THE AREA FOR THE NEXT 48 HOURS.

THE REST OF THE CARIBBEAN SEA...

AN AREA OF DISTURBED WEATHER HAS FORMED IN THE SOUTHWESTERN
CARIBBEAN SEA.  SLOW DEVELOPMENT OF THIS SYSTEM IS POSSIBLE
DURING THE NEXT COUPLE OF DAYS AS IT MOVES NORTHWESTWARD SLOWLY.
THIS SYSTEM HAS A LOW CHANCE OF BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS. CONDITIONS APPEAR TO BE CONDUCIVE FOR
SOME DEVELOPMENT AFTER 48 HOURS...AS THE SYSTEM MOVES TOWARD THE
NORTHWESTERN CARIBBEAN SEA AND SOUTHEASTERN GULF OF MEXICO. THIS
SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING
THE NEXT 5 DAYS. AN UPPER LEVEL RIDGE EXTENDS FROM SOUTHWESTERN
HAITI... SOUTHWARD...BEYOND THE GULF OF URABA OF COLOMBIA. BROAD
SURFACE LOW PRESSURE...INCLUDING AROUND THE MONSOON TROUGH...
COVERS THE CARIBBEAN SEA TO THE SOUTH OF 16N TO THE WEST OF 69W.
NUMEROUS STRONG CONVECTIVE PRECIPITATION COVERS THE CARIBBEAN
SEA TO THE SOUTH OF 16N BETWEEN 72W AND 78W. WIDELY SCATTERED
MODERATE TO ISOLATED STRONG CONVECTIVE PRECIPITATION COVERS THE
REST OF THE CARIBBEAN SEA TO THE SOUTH OF 16N TO THE WEST OF 78W.

THE MONSOON TROUGH EXTENDS FROM NORTHERN COLOMBIA NEAR 9N74W TO
9N79W IN PANAMA...BEYOND TO 10N86W IN COSTA RICA...INTO THE
EASTERN PACIFIC OCEAN.

THE REST OF THE ATLANTIC OCEAN...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH IS ALONG 24N26W...TO A
COMPARATIVELY WEAK 17N34W CYCLONIC CIRCULATION CENTER...TO
13N37W. NO SIGNIFICANT DEEP CONVECTIVE PRECIPITATION IS
APPARENT.

A 1023 MB HIGH PRESSURE CENTER IS NEAR 26N39W. SURFACE
ANTICYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN TO THE NORTH OF
18N BETWEEN AFRICA AND 44W.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...FOR MORE
DETAILS ABOUT THE STATIONARY FRONT FROM 31N55W TO A 1008 MB LOW
PRESSURE CENTER NEAR 29N70W...NORTHEAST WINDS 20 TO 25 KNOTS AND
8 FOOT SEA HEIGHTS WITHIN 90 NM OF THE LOW CENTER IN THE
NORTHERN QUADRANT. EXPECT SOUTHWESTERLY WINDS 20 TO 25 KNOTS AND
9 TO 13 FOOT SEA HEIGHTS TO THE NORTH OF 29N BETWEEN 46W AND
52W. ALSO EXPECT WINDS 20 KNOTS OR LESS AND SEA HEIGHTS TO 10
FEET ELSEWHERE TO THE NORTH OF 28N BETWEEN 41W AND 55W. A SECOND
FEATURE IS A 1011 MB LOW PRESSURE CENTER THAT IS NEAR 23N50.5W.
EXPECT WINDS 20 TO 30 KNOT AND SEA HEIGHTS TO 9 FEET WITHIN 90
NM OF THE LOW CENTER IN THE EAST SEMICIRCLE. A THIRD AREA
CONSISTS OF WINDS 20 KNOTS OR LESS AND SEA HEIGHTS TO 9 FEET TO
THE SOUTH OF 16N TO THE EAST OF 45W.

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

$$
MT


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