[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 152346
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON JUL 15 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 22N43W TO 11N44W MOVING W AT 20-25
KT. THE WAVE IS EMBEDDED WITHIN A LARGE SURGE OF DEEP LAYER
MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY.
HOWEVER...A SAHARAN AIR LAYER WRAPS AROUND THE WAVE...WHICH IS
LIMITING ANY DEEP CONVECTION TO THE ITCZ REGION. ONLY A SMALL
AREA OF MODERATE CONVECTION IS FROM 9N-10N BETWEEN 41W-44W.

TROPICAL WAVE EXTENDS FROM 16N55W TO 5N55W MOVING W NEAR 20 KT.
THE WAVE REMAINS ON THE LEADING EDGE OF THE SAHARAN AIR
LAYER...AND ALIGNS WITH A NARROW AREA OF INCREASED MOISTURE
EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 3N-6N BETWEEN 53W-
55W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE COAST OF GUINEA-BISSAU NEAR
12N16W TO 8N20W 7N26W. THE ITCZ BEGINS NEAR 7N26W AND CONTINUES
ALONG 7N35W 11N45W 7N53W. ISOLATED MODERATE CONVECTION IS FROM
5N-8N BETWEEN 16W-19W...AND FROM 5N-8N BETWEEN 35W-39W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-8N
BETWEEN 31W-33W.

...DISCUSSION...

GULF OF MEXICO...
MOIST CONDITIONS ARE THROUGHOUT MUCH OF THE GULF OF MEXICO THIS
EVENING ASSOCIATED WITH UPPER LEVEL TROUGHING OVER THE WESTERN
GULF CENTERED NEAR 22N93W. MOISTURE STREAMS AROUND THE UPPER
TROUGH/LOW AND AROUND A NARROW UPPER RIDGE ALONG 87W. A SECOND
UPPER TROUGH/LOW IS IMPACTING FLORIDA CENTERED IN THE WEST ATLC.
CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE
THROUGHOUT THE BASIN MAINLY EAST OF 95W. LOW-LEVEL MOISTURE IS
ALSO STREAMING THROUGHOUT THE AREA IN MAINLY EAST TO SOUTHEAST
WINDS RANGING FROM 10-15 KT. AS OF 2100 UTC...A SURFACE TROUGH
IS ANALYZED ALONG 29N88W TO 25N87W. BROAD CYCLONIC FLOW IS
AROUND THE TROUGH AXIS AS INDICATED BY AN EARLIER ASCAT
SCATTEROMETER PASS. LITTLE CHANGE IS EXPECTED OVER THE NEXT 24
HOURS AS A DIFFLUENT PATTERN ALOFT REMAINS ALONG WITH ABUNDANT
MOISTURE.

CARIBBEAN SEA...
THE UPPER LEVEL RIDGE OVER THE EASTERN GULF OF MEXICO CONTINUES
INTO THE WESTERN CARIBBEAN ALONG 85W. WATER VAPOR IMAGERY
INDICATES RELATIVELY DRY AIR ALOFT IS OVER THE BASIN AROUND THE
UPPER RIDGE...WHICH CONTINUES AROUND UPPER TROUGHING OVER THE
CENTRAL CARIBBEAN...AND AROUND ANOTHER UPPER RIDGE OVER THE
EASTERN CARIBBEAN. THE DRY AIR ALOFT IS HELPING MAINTAIN FAIR
CONDITIONS THROUGHOUT THE CARIBBEAN WATERS EXCEPT FOR A FEW
ISOLATED SHOWERS OVER THE WESTERN PORTIONS EMBEDDED WITHIN
TRADEWIND FLOW OF 15-20 KT. HOWEVER...AFTERNOON
SHOWERS/THUNDERSTORMS HAVE BUILT UP OVER SEVERAL OF THE ISLANDS
INCLUDING CUBA...JAMAICA...AND HAITI. SCATTERED
SHOWERS/THUNDERSTORMS ARE ALSO THROUGHOUT PANAMA ASSOCIATED WITH
THE MONSOON TROUGH THAT EXTENDS THROUGH THE COUNTRY TO A 1007 MB
LOW OVER NORTHERN COLOMBIA. LITTLE CHANGE IS EXPECTED OVER THE
NEXT 24 HOURS EXCEPT FOR A TROPICAL WAVE EAST OF THE LESSER
ANTILLES THAT WILL LIKELY REACH THE ISLANDS WITHIN THE NEXT 12
HOURS. THE INCREASED MOISTURE WILL LIKELY LEAD TO ISOLATED
SHOWERS THROUGHOUT THE EASTERN CARIBBEAN FOR THE NEXT DAY OR SO.

HISPANIOLA...                                           A
CLUSTER OF STRONG SHOWERS/THUNDERSTORMS IS OVER MUCH OF NORTHERN
HAITI FROM 19N-20N BETWEEN 71W-73W. THIS ACTIVITY IS THE
COMBINATION OF DAYTIME HEATING COMBINED WITH UPPER LEVEL
DIFFLUENCE AROUND THE BASE OF A BROAD UPPER LOW OVER THE WEST
ATLC. THE UPPER LOW IS EXPECTED TO DRIFT WEST WHICH WILL
CONTINUE TO KEEP DIFFLUENT FLOW OVER THE ISLAND FOR THE NEXT DAY
OR SO. ACTIVITY WILL BE MOST LIKELY IN THE AFTERNOONS DURING
PEAK HEATING AND INSTABILITY.

ATLANTIC OCEAN...
A BROAD UPPER LEVEL LOW COVERS THE WEST ATLC WITH A MAIN CENTER
NEAR 28N75W. THE COMPLEX SYSTEM SUPPORTS TWO SURFACE TROUGHS.
THE FIRST IS NEAR THE EAST FLORIDA COAST ALONG 31N81W TO 26N79W.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE TO THE EAST FROM
25N-29N BETWEEN 73W-79W. THE SECOND SURFACE TROUGH IS ALONG
28N78W TO 21N64W. ISOLATED SHOWERS/THUNDERSTORMS ARE WITHIN 320
NM EAST...AND 130 NM WEST OF THE AXIS. UPPER RIDGING IS TO THE
EAST ALONG 57W SUPPORTING A WEAK 1023 MB HIGH NEAR 28N49W. A
SECOND 1025 MB HIGH CENTER IS NEAR 30N32W PROVIDING SURFACE
RIDGING ACROSS THE REMAINDER OF THE EAST ATLC. THIS HIGH CENTER
IS SUPPORTED BY AN UPPER LEVEL RIDGE CENTERED NEAR 21N33W. MUCH
OF THE EASTERN ATLC IS ALSO COVERED BY A VERY STABLE SAHARAN AIR
LAYER EXTENDING TO ALMOST 40W AND THEN WRAPPING AROUND A
TROPICAL WAVE NEAR 44W.

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

$$
WALTON


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