[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191747
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI JUL 19 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.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 10N42W TO 21N39W MOVING W AT 15-20
KT. THE WAVE COINCIDES WITH A BROAD GLOBAL MODEL INDICATED 700
MB TROUGH AXIS ALONG 40W AND A MAXIMUM IN TOTAL PRECIPITABLE
WATER IMAGERY FROM 10N-19N BETWEEN 32W-42W...PRIMARILY TO THE
EAST OF THE WAVE AXIS. NO SIGNIFICANT DEEP CONVECTION IS
ASSOCIATED THE WAVE AT THIS TIME DUE TO THE STABLING EFFECT OF
THE SAHARAN AIR LAYER ACROSS THE EASTERN ATLC.

TROPICAL WAVE EXTENDS FROM 09N75W TO 18N75W MOVING W AT 15-20
KT. THE WAVE IS ASSOCIATED WITH BROAD LOWER LEVEL TROUGHING
ACROSS THE EASTERN CARIBBEAN WITH TOTAL PRECIPITABLE WATER
IMAGERY INDICATING THE WAVE ENERGY CONTINUES TO STRETCH TO THE
NORTH AS A SURFACE TROUGH IS ANALYZED FROM THE NORTHERN TIP OF
THE WAVE AXIS NEAR 19N75W TO 24N72W. ISOLATED MODERATE
CONVECTION IS FROM 19N-22N BETWEEN 75W-77W...WITH WIDELY
SCATTERED SHOWERS COVERING A LARGER AREA FROM 16N-23N BETWEEN
68W-77W. THIS WAVE PRODUCED A 24 HOUR RAINFALL TOTAL OF 8.91
INCHES AT SAN JUAN PUERTO RICO FROM 18/1200 UTC TO 19/1200 UTC.

TROPICAL WAVE EXTENDS FROM 07N85W TO 17N83W MOVING W AT 10-15
KT. THE WAVE CONTINUES TO PROGRESS ACROSS CENTRAL AMERICA THIS
AFTERNOON BENEATH NORTHERLY AND DIFFLUENT FLOW ALOFT...WHICH IS
GENERATING SCATTERED MODERATE CONVECTION FROM 10N-18N BETWEEN
83W-87W. THE WAVE IS EXPECTED TO CONTINUE ACROSS THE REMAINDER
OF CENTRAL AMERICA THROUGH THIS EVENING AND EMERGE INTO THE
EASTERN PACIFIC REGION THEREAFTER.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W TO
06N24W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
06N24W TO 05N31W TO 10N41W TO 06N57W. ISOLATED MODERATE
CONVECTION IS FROM 04N-08N BETWEEN 44W-53W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES A UPPER LEVEL LOW IS CENTERED OVER
THE NORTH-CENTRAL GULF NEAR 29N91W THAT CONTINUES TO CREATE LIFT
AND ADVECT MOISTURE OVER A MAJORITY OF THE BASIN...INCLUDING
PORTIONS OF THE FLORIDA PENINSULA THIS AFTERNOON. MUCH OF THE
PRECIPITATION AND CONVECTION IS FOCUSED ALONG A SURFACE TROUGH
ANALYZED FROM THE FLORIDA PANHANDLE NEAR 30N85W TO 23N94W WITH
NUMEROUS SHOWERS AND SCATTERED TSTMS OCCURRING FROM 23N-30N
BETWEEN 82W-89W...AND WITHIN 120 NM EITHER SIDE OF THE SURFACE
TROUGH. ISOLATED SHOWERS AND TSTMS ARE ALSO DRIFTING SOUTHWARD
OFF THE EASTERN TEXAS GULF COAST FROM N OF 27N BETWEEN 92W-96W.
THE SURFACE TROUGH IS EXPECTED TO DRIFT WESTWARD IN TANDEM WITH
THE UPPER LEVEL LOW OVER THE NEXT FEW DAYS WITH THE SURFACE
FEATURE EVENTUALLY DISSIPATING ALONG THE LOUISIANA AND TEXAS
GULF COAST IN THE NW GULF SATURDAY. THEREAFTER...SURFACE RIDGING
ANCHORED IN THE SW NORTH ATLC WILL EXTEND WESTWARD AND ONCE
AGAIN RE-ESTABLISH SE TO S WINDS ACROSS THE BASIN OVER THE
REMAINDER OF THE WEEKEND.

CARIBBEAN SEA...
A WEAK UPPER LEVEL LOW IS CENTERED OVER THE SOUTHERN CARIBBEAN
NEAR 11N72W WITH CYCLONIC FLOW ALOFT INFLUENCE STRETCHING TO 20N
BETWEEN 61W-75W. WATER VAPOR IMAGERY INDICATES THIS UPPER LEVEL
FEATURE REMAINS MODERATELY DRY WITH CONDITIONS AT THE SURFACE
CONTINUING TO EXPERIENCE FAIR SKIES AND AN OVERALL LACK OF ANY
SIGNIFICANT DEEP CONVECTION. A FEW ISOLATED SHOWERS ARE NOTED N
OF 17N BETWEEN 71W-75W...IMPACTING HISPANIOLA AND THE ADJACENT
COASTAL WATERS. OTHERWISE...THE MAIN FEATURES ARE TWO TROPICAL
WAVE PROGRESSING WESTWARD OVER THE WESTERN CARIBBEAN. ONE WAVE
IS ALONG 76W WITH A PORTION OF ITS ENERGY FRACTURING NORTHWARD
AS A SURFACE TROUGH ANALYZED FROM THE WINDWARD PASSAGE N-NE TO
24N72W. WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE
OCCURRING N OF 19N BETWEEN 74W-77W. THE OTHER TROPICAL WAVE IS
ALONG 84W AND IS LARGELY INLAND ACROSS NICARAGUA AND COSTA RICA.
A SMALL PORTION EXTENDS INTO THE NW CARIBBEAN NEAR 17N83W.
SCATTERED SHOWERSE AND TSTMS ARE OCCURRING OVER THE NW CARIBBEAN
NORTH OF THE HONDURAS COAST FROM 15N-18N BETWEEN 82W-86W.
STRONGER CONVECTION...SCATTERED SHOWERS AND TSTMS ARE OCCURRING
S OF 13N BETWEEN 78W-86W IN THE VICINITY OF THE TROPICAL WAVE
AND MORE LIKELY ASSOCIATED WITH THE MONSOON TROUGH AXIS
EXTENDING ALONG 09N BETWEEN NORTHERN COLOMBIA AND SOUTHERN COSTA
RICA.

HISPANIOLA...
REMNANT MOISTURE LEFT FROM THE PASSAGE OF A TROPICAL WAVE
YESTERDAY AND OVERNIGHT CONTINUES TO PRODUCE ISOLATED SHOWERS
AND TSTMS THIS AFTERNOON ACROSS THE ISLAND AND ADJACENT COASTAL
WATERS FROM 17N-22N BETWEEN 69W-75W. WITH SE WINDS DOMINATING
AND OVERALL CLEARING SKIES TO THE EAST...CONDITIONS SHOULD
IMPROVE OVER THE NEXT 24 HOURS WITH A SLIGHT CHANCE FOR
AFTERNOON ISOLATED SHOWERS DUE TO PEAK DAYTIME HEATING AND
INSTABILITY. OTHERWISE...THE WEEKEND SHOULD REMAIN FAIRLY
TRANQUIL DUE TO SURFACE RIDGING BUILDING OVER THE REGION THROUGH
MONDAY. THE NEXT TROPICAL WAVE...CURRENTLY ANALYZED OVER THE
CENTRAL ATLC...IS FORECAST TO IMPACT HISPANIOLA LATE MONDAY INTO
TUESDAY.

ATLANTIC OCEAN...
A BROAD UPPER LEVEL LOW IS CENTERED OVER THE NORTH-CENTRAL GULF
OF MEXICO NEAR 29N91W THAT SUPPORTS A SURFACE TROUGH ANALYZED
ACROSS THE GULF OF MEXICO. MOISTURE ADVECTING FROM THE GULF OF
MEXICO OVER THE FLORIDA PENINSULA AND INTO THE SW NORTH ATLC IS
PROVIDING FOR SCATTERED SHOWERS AND TSTMS N OF 22N W OF 74W AND
CONTINUES TO BE ENHANCED BY MARGINAL MIDDLE TO UPPER LEVEL
DIFFLUENCE. THE APPROACH OF A SURFACE TROUGH...FRACTURED ENERGY
FROM A TROPICAL WAVE ACROSS THE CENTRAL CARIBBEAN SEA...IS ALSO
BEGINNING TO IMPACT THIS AREA AND WILL LIKELY SUSTAIN GENERATION
OF CONVECTION OVER THE NEXT 24 TO 36 HOURS ACROSS THE BAHAMAS
AND PORTIONS OF THE FLORIDA PENINSULA...INCLUDING ADJACENT
COASTAL WATERS. OTHERWISE...THE REMAINDER OF THE CENTRAL AND
EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED
BY A 1025 MB HIGH CENTERED NEAR 28N58W AND A 1023 MB HIGH
CENTERED NEAR 30N29W. SATELLITE IMAGERY INDICATES THE SAHARAN
AIR LAYER CONTINUES TO IMPACT MUCH OF THE EASTERN AND CENTRAL
ATLC GENERALLY N OF 12N E OF 60W.

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

$$
HUFFMAN


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