[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 070551
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN JUL 07 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...SPECIAL FEATURES...
A TROPICAL WAVE EXTENDS FROM 16N45W TO A WEAK 1009 MB SURFACE
LOW NEAR 8N37W MOVING WEST AT 15-20 KT. THE WAVE AXIS IS
EMBEDDED WITHIN A DRY SAHARAN AIR LAYER...WHICH IS LIMITING
CONVECTION NEAR THE MAJORITY OF THE AXIS EXCEPT NEAR THE LOW
CENTER. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WEST OF
THE LOW CENTER FROM 6N-10N BETWEEN 37W-41W. THIS SYSTEM HAS A
MEDIUM CHANCE OF DEVELOPMENT INTO A TROPICAL CYCLONE OVER THE
NEXT 48 HOURS.

...TROPICAL WAVES...
TROPICAL WAVE IN THE CENTRAL ATLC IS DISCUSSED ABOVE IN THE
SPECIAL FEATURES SECTION

TROPICAL WAVE IS ALONG 23N64W TO 15N69W MOVING WEST NEAR 15 KT.
THE WAVE ALIGNS WITH A SURGE OF DEEP LAYER MOISTURE PRESENT IN
TOTAL PRECIPITABLE WATER IMAGERY. NO DEEP CONVECTION IS CURRENTLY
LOCATED NEAR THE WAVE.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE COAST OF MAURITANIA NEAR
19N16W TO 13N22W 11N27W. THE ITCZ BEGINS NEAR 11N27W AND
CONTINUES ALONG 9N35W 3N52W. SCATTERED MODERATE/STRONG
CONVECTION IS FROM 7N-12N BETWEEN 14W-22W.

...DISCUSSION...

GULF OF MEXICO...
MOIST CONDITIONS REMAIN ACROSS MUCH OF THE GULF OF MEXICO. THIS
IS DUE TO A COMBINATION OF MOIST SOUTHERLY TO SOUTHEASTERLY FLOW
AT THE SURFACE...AND MOIST FLOW ALOFT AROUND AN UPPER LEVEL
RIDGE WITH AXIS FROM 31N85W TO 21N97W. ISOLATED SHOWERS AND
POSSIBLE THUNDERSTORMS ARE THROUGHOUT THE AREA. A SURFACE TROUGH
LINES THE NW GULF COAST ALONG 31N90W TO 26N97W...WHICH IS
HELPING CONTRIBUTE TO SOME OF THE SHOWERS IN THE AREA. THE
SURFACE TROUGH IS SUPPORTED BY AN UPPER TROUGH WHICH IS ALSO
ALONG THE NW GULF COAST. A SECOND SURFACE TROUGH IS ALONG THE
YUCATAN PENINSULA ALONG 23N89W TO 18N92W. THE SURFACE TROUGH IN
THE NW CORNER IS EXPECTED TO DRIFT N2 OVER THE DAY DAY OR SO AS
SURFACE RIDGING BUILDS OVER THE BASIN. MOIST CONDITIONS WILL
REMAIN ACROSS MUCH OF THE AREA FOR AT LEAST THE NEXT 24 HOURS.

CARIBBEAN SEA...
MOISTURE FROM THE GULF OF MEXICO IS BEING DRAWN OVER THE NW
CARIBBEAN IN NORTHERLY FLOW ALOFT AROUND AN UPPER LEVEL RIDGE
OVER THE GULF. ONLY A FEW CLUSTERS OF SHOWERS/THUNDERSTORMS ARE
FROM 19N-21N BETWEEN 77W-82W...AND FROM 21N-23N BETWEEN 82W-85W.
SCATTERED SHOWERS/THUNDERSTORMS ARE IN THE EXTREME SW CARIBBEAN
OVER PANAMA AND COSTA RICA ASSOCIATED WITH THE MONSOON TROUGH
THAT EXTENDS THROUGH BOTH COUNTRIES TO NORTHERN COLOMBIA. THE
REMAINDER OF THE BASIN IS FAIRLY DRY EXCEPT FOR ISOLATED SHOWERS
OVER THE NE CORNER NORTH OF 16N EAST OF 71W ASSOCIATED WITH A
TROPICAL WAVE MOVING THROUGH THE MONA PASSAGE. ALOFT...A NARROW
UPPER TROUGH EXTENDS FROM THE WINDWARD PASSAGE TO
NICARAGUA...BUT IS ACCOMPANIED BY DRY AIR ALOFT. UPPER LEVEL
RIDGING COVERS THE REMAINDER OF THE BASIN ALSO ACCOMPANIED BY
DRY AIR ALOFT. TRADEWIND FLOW OF 15-20 KT IS THROUGHOUT MUCH OF
THE AREA. THE WAVE IS EXPECTED TO CONTINUE MOVING WEST WITH
LITTLE CHANGE ELSEWHERE.

HISPANIOLA...
ONLY A SMALL AREA OF SHOWERS/THUNDERSTORMS IS OVER THE SOUTHERN
PORTION OF HAITI WITH THE REMAINDER OF THE ISLAND EXPERIENCING
FAIR CONDITIONS. DRY AIR ALOFT IS HELPING KEEP CONDITIONS FAIR.
HOWEVER...MOISTURE ASSOCIATED WITH A TROPICAL WAVE IS JUST EAST
IN THE MONA PASSAGE AND WILL LIKELY BEGIN TO IMPACT THE ISLAND
SOON. THIS WILL MOST LIKELY LEAD TO INCREASED AFTERNOON
CONVECTION.

ATLANTIC OCEAN...
BROAD SURFACE RIDGING DOMINATES THE WEST ATLC AROUND A 1023 MB
HIGH NEAR 33N73W. THE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE
CENTERED NEAR 34N74W. HOWEVER...AN UPPER LEVEL LOW TO THE SOUTH
NEAR 24N69W SUPPORTS A WEAK SURFACE TROUGH NEAR 27N71W ALONG
WITH A FEW ISOLATED SHOWERS FROM 22N-26N BETWEEN 66W-70W. A
TROPICAL WAVE IS TO THE EAST SUPPORTING A FEW ISOLATED SHOWERS
FROM 19N-23N BETWEEN 62W-66W. A DISSIPATING STATIONARY FRONT TO
THE NORTH EXTENDS INTO THE AREA ALONG 31N41W TO 28N60W
SUPPORTING ISOLATED SHOWERS WITHIN 60 NM. THE FRONT IS
SUPPORTED BY AN UPPER LEVEL LOW NEAR 31N42W. THE REMAINDER OF
THE BASIN IS DOMINATED BY BROAD SURFACE RIDGING ANCHORED BY A
1021 MB HIGH NEAR 28N33W. ALOFT...UPPER RIDGING DOMINATES THE
TROPICAL ATLC CENTERED NEAR 13N59W. A SECOND UPPER RIDGE IS
CENTERED NEAR 30N30W. VERY DRY AIR IS THROUGHOUT THE EAST ATLC
DUE TO THE PRESENCE OF A BROAD SAHARAN AIR LAYER...WHICH IS
KEEPING CONDITIONS FAIR ACROSS MUCH OF THE AREA.

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

$$
WALTON


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