[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 241755
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI JUL 24 2015

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 07N39W TO 14N38W MOVING W AT 20 KT.
THE WAVE COINCIDES WITH WEAK 700 MB TROUGHING BETWEEN 34W-43W
WITH A WEAK MAXIMUM OF 850 MB RELATIVE VORTICITY ALONG THE WAVE
AXIS NEAR 11N. NO SIGNIFICANT CONVECTION IS OCCURRING IN
ASSOCIATION WITH THE WAVE AT THIS TIME DUE TO A STRONG SAHARAN
AIR LAYER PROVIDING OVERALL STABLE CONDITIONS OVER THE TROPICAL
EASTERN ATLC.

TROPICAL WAVE EXTENDS FROM 05N56W TO 14N51W MOVING W AT 15-20
KT. THE WAVE HAS CONTINUED TO GRADUALLY AMPLIFY AND EXAMINING
PAST GLOBAL MODEL ANALYSES...GAINED STRETCHED OUT FASTER MOVING
LOW-LEVEL ENERGY THAT APPEARS TO HAVE FRACTURED AWAY FROM THE
WAVE TO THE EAST. THE WAVE IS FORECAST TO BRING INCREASED
PRECIPITATION PROBABILITY TO THE WINDWARD ISLANDS AND NE
VENEZUELA THIS WEEKEND. ISOLATED MODERATE CONVECTION IS FROM 07N-
11N BETWEEN 53W-60W.

TROPICAL WAVE EXTENDS FROM 09N80W TO 17N81W MOVING W AT 15-20
KT. THE WAVE REMAINS EMBEDDED WITHIN A MAXIMUM OF TOTAL
PRECIPITABLE WATER ACROSS THE WESTERN CARIBBEAN SEAS BETWEEN 76W-
84W. ISOLATED MODERATE CONVECTION IS FROM 09N-12N BETWEEN 81W-
85W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
13N17W TO 10N20W TO 09N30W TO 07N39W. THE INTERTROPICAL
CONVERGENCE ZONE AXIS EXTENDS FROM 07N39W TO 07N46W TO 10N53W.
SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 07N-
12N BETWEEN 17W-28W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER LEVEL LOW CENTERED NEAR 23N95W INFLUENCES THE
WESTERN GULF WHILE AN UPPER LEVEL RIDGE AXIS EXTENDING FROM OVER
THE LOWER MISSISSIPPI RIVER VALLEY NEAR 31N92W TO OVER THE SW
FLORIDA PENINSULA NEAR 26N82W INFLUENCES THE EASTERN GULF. WATER
VAPOR IMAGERY INDICATES MOST OF THE MOISTURE OVER THE BASIN IS
ASSOCIATED WITH THE RIDGE AS IT PROVIDES AN UPPER LEVEL
DIFFLUENT ENVIRONMENT FOR ONGOING ACTIVE CONVECTION. AT THE
SURFACE BENEATH THE UPPER LEVEL RIDGE...WEAK FRONTAL TROUGHING
FOCUSED ALONG A SURFACE TROUGH ANALYZED FROM NEAR JACKSONVILLE
FLORIDA SW TO 28N85W CONTINUES TO PROVIDE FOCUS FOR SCATTERED
SHOWERS AND TSTMS OCCURRING GENERALLY EAST OF A LINE FROM 30N89W
TO 25N83W. OTHERWISE...A SURFACE RIDGE ANCHORED BY A 1019 MB
HIGH CENTERED IN THE SE GULF NEAR 24N84W CONTINUES TO PROMOTE
FAIR SKIES AND CONDITIONS ACROSS MUCH OF THE WESTERN GULF AND
PORTIONS OF THE SE GULF IN THE VICINITY OF AND NORTH OF THE
YUCATAN CHANNEL REGION. THE SURFACE RIDGING IS EXPECTED TO
REMAIN ANCHORED ACROSS THE CENTRAL GULF THIS WEEKEND WITH GENTLE
TO MODERATE ANTICYCLONIC BREEZE CONDITIONS THROUGH SUNDAY.

CARIBBEAN SEA...
A VERY BROAD CUTOFF UPPER LEVEL LOW IS CENTERED OVER THE
APPROACHES TO THE WINDWARD PASSAGE NEAR 19N75W THAT INFLUENCES
THE WESTERN CARIBBEAN W OF 77W WITH RELATIVELY DRY AIR ALOFT AND
OVERALL STABLE CONDITIONS THIS AFTERNOON. MOST MOISTURE W OF 77W
IS NOTED S OF 13N WITHIN AN AREA OF MAXIMUM MIDDLE TO UPPER
LEVEL DIFFLUENCE ALONG WITH A TROPICAL WAVE ALONG 81W MOVING
ACROSS THE SW CARIBBEAN. SCATTERED SHOWERS AND TSTMS ARE
OCCURRING S OF 13N BETWEEN 81W-85W...INCLUDING PORTIONS OF
WESTERN PANAMA...COSTA RICA...AND NICARAGUA. OTHERWISE...E OF
77W...MIDDLE TO UPPER LEVEL MOISTURE INCREASES DUE TO
SOUTHWESTERLY FLOW ALOFT...HOWEVER LOW-LEVEL MOISTURE REMAINS
SCARCE DUE TO THE SAHARAN AIR LAYER PROVIDING STABLE CONDITIONS
IN THE LOWER LEVELS OF THE ATMOSPHERE OVER THE EASTERN CARIBBEAN
WITH MOSTLY CLEAR SKIES PREVAILING. LASTLY...MODERATE TO FRESH
TRADES PREVAIL OUTSIDE OF THE SOUTH-CENTRAL CARIBBEAN AND
COLOMBIA COAST REGION WHERE SLIGHTLY STRONGER E-NE WINDS ARE
OCCURRING IN THE FRESH TO STRONG BREEZE RANGE.

...HISPANIOLA...
CURRENTLY...SKIES REMAIN MOSTLY CLEAR WITH A LACK OF ANY
SIGNIFICANT CONVECTION AT THIS TIME OCCURRING IN THE REGION DUE
THE SAHARAN AIR LAYER PROVIDING AN OVERALL STABLE ENVIRONMENT.
DRY CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE EVENING AND
OVERNIGHT HOURS INTO SATURDAY.

ATLANTIC OCEAN...
A LONGWAVE MIDDLE TO UPPER LEVEL TROUGH IS EVIDENT ON WATER
VAPOR IMAGERY OVER THE WESTERN NORTH ATLC THAT SUPPORTS A
STATIONARY FRONT EXTENDING FROM 34N60W INTO A 1011 MB LOW
CENTERED NEAR 34N76W THEN TO THE SOUTH CAROLINA COAST NEAR
33N80W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING IN
THE VICINITY OF THE FRONT WITHIN 120 NM EITHER SIDE. A PRE-
FRONTAL SURFACE TROUGH EXTENDS FROM 31N77W TO 27N79W AND IS
PROVIDING FOCUS OF MAXIMUM LOW-LEVEL MOISTURE CONVERGENCE IN
WHICH SCATTERED SHOWERS AND TSTMS ARE OCCURRING N OF 27N W OF
72W. FARTHER EAST...A SURFACE RIDGE AXIS EXTENDING FROM 26N56W
TO 24N76W INFLUENCES THE REMAINDER OF THE SW NORTH ATLC WITH
ONLY A FEW ISOLATED SHOWERS OCCURRING FROM 26N-30N BETWEEN 55W-
62W. IN BETWEEN THIS RIDGE AND ANOTHER RIDGE TO THE EAST...A
SURFACE TROUGH EXTENDS FROM 24N51W TO 31N48W. THE SURFACE TROUGH
COINCIDES WITH AN UPPER LEVEL LOW CENTERED NEAR 26N51W THAT
CONTINUES TO GENERATE ISOLATED SHOWERS WITHIN 120 NM EITHER SIDE
OF THE BOUNDARY. LASTLY...THE EASTERN ATLC IS INFLUENCED BY A
SURFACE RIDGE ANCHORED ON A 1028 MB HIGH CENTERED NEAR 33N32W.

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

$$
HUFFMAN
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