[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 162345
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE JUL 16 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 17N18W TO 4N18W MOVING WEST AT 15-20
KT. UPPER AIR SOUNDINGS FROM DAKAR SENEGAL INDICATE THE WAVE
MOVING OFF THE COAST OF AFRICA BETWEEN 16/0000 AND 16/1200 UTC.
THE WAVE ALSO COINCIDES WITH A 700 MB TROUGH AXIS AND A SURGE OF
MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED
MODERATE/STRONG CONVECTION IS FROM 6N-9N BETWEEN 17W-20W.

TROPICAL WAVE EXTENDS FROM 2052W TO 11N50W MOVING W NEAR 20 KT.
THE WAVE IS EMBEDDED WITHIN A LARGE SURGE OF DEEP LAYER MOISTURE
PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. ISOLATED MODERATE
CONVECTION IS FROM 13N-18N BETWEEN 48W-54W.

TROPICAL WAVE EXTENDS FROM 18N63W TO 10N61W MOVING W NEAR 15 KT.
THE WAVE ALIGNS WITH A NARROW AREA OF INCREASED MOISTURE EVIDENT
IN TOTAL PRECIPITABLE WATER IMAGERY. NO DEEP CONVECTION IS
CURRENTLY ASSOCIATED WITH THE WAVE.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE COAST OF MAURITANIA NEAR
19N16W TO 12N23W 6N34W. THE ITCZ BEGINS NEAR 6N34W AND CONTINUES
TO 5N55W. ISOLATED MODERATE CONVECTION IS FROM 4N-8N BETWEEN 23W-
32W.

...DISCUSSION...

GULF OF MEXICO...
MOIST CONDITIONS CONTINUE THROUGHOUT MUCH OF THE GULF OF MEXICO
THIS EVENING ASSOCIATED WITH SEVERAL UPPER LEVEL LOW CENTERS. A
TIGHTLY SPUN UPPER LOW IS MOVING INTO NEW MEXICO WITH A TROUGH
AXIS CONTINUING THROUGH TEXAS INTO THE WESTERN GULF. THIS UPPER
TROUGH IS PROVIDING DIFFLUENT FLOW OVER THE NW GULF. A SECOND
UPPER LOW IS CENTERED JUST WEST OF THE YUCATAN PENINSULA NEAR
22N92W PROVIDING DIFFLUENT FLOW OVER THE PENINSULA. A THIRD
UPPER LOW IS OVER CENTRAL FLORIDA NEAR 27N83W PROVIDING
DIFFLUENT FLOW OVER FLORIDA INCLUDING THE PANHANDLE. WEAK UPPER
RIDGING IS SANDWICHED OVER THE NORTH CENTRAL GULF. THIS COMPLEX
PATTERN IS PROVIDING INSTABILITY OVER SEVERAL AREAS GIVING WAY
TO SHOWER/THUNDERSTORM ACTIVITY. SCATTERED SHOWERS/THUNDERSTORMS
ARE MOST CONCENTRATED OVER THE NE GULF NORTH OF 27N EAST OF
86W...AND CONTINUE WESTWARD ALONG THE GULF COAST. ACTIVITY NEAR
FLORIDA IS ALSO BEING ENHANCED BY A SURFACE TROUGH ALONG 28N82W
TO 22N81W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE ALSO
OVER THE WESTERN GULF FROM 20N-28N BETWEEN 92W-97W. THIS
ACTIVITY IS ENHANCED BY A SECOND SURFACE TROUGH ALONG 27N97W TO
19N94W. WINDS AT THE SURFACE ARE PRIMARILY EAST TO SOUTHEAST
RANGING FROM 10-15 KT. LITTLE CHANGE IS EXPECTED OVER THE NEXT
24 HOURS.

CARIBBEAN SEA...
UPPER LEVEL RIDGING COVERS THE WESTERN CARIBBEAN CENTERED OVER
HONDURAS. WATER VAPOR IMAGERY INDICATES RELATIVELY DRY AIR ALOFT
IS OVER THE BASIN AROUND THE UPPER RIDGE...WHICH CONTINUES
AROUND BROAD 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 SOME ISOLATED/THUNDERSTORMS SHOWERS
OVER THE NORTHWESTERN PORTIONS EMBEDDED WITHIN TRADEWIND FLOW OF
15-25 KT. HOWEVER...AFTERNOON SHOWERS/THUNDERSTORMS HAVE BUILT
UP OVER SEVERAL OF THE ISLANDS INCLUDING CUBA...JAMAICA...AND
HISPANIOLA. SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO IN THE SW
CARIBBEAN SOUTH OF 13N BETWEEN 78W-83W ASSOCIATED WITH THE
MONSOON TROUGH THAT EXTENDS THROUGH PANAMA TO A 1005 MB LOW OVER
NORTHERN COLOMBIA. A TROPICAL WAVE HAS MOVED INTO THE EASTERN
CARIBBEAN NEAR 62W. HOWEVER...NO SHOWERS/THUNDERSTORMS ARE
ASSOCIATED WITH THE WAVE AT THIS TIME. THE TROPICAL WAVE IS
EXPECTED TO CONTINUE WESTWARD. A SECOND WAVE FARTHER EAST WILL
LIKELY BRING MORE MOISTURE TO THE LESSER ANTILLES THAN THE
CURRENT WAVE. THE MOISTURE COULD REACH THE ISLAND WITHIN 24
HOURS AND PROVIDE ISOLATED SHOWERS.

HISPANIOLA...
SCATTERED SHOWERS/THUNDERSTORMS ARE ACROSS NORTHERN HISPANIOLA
FROM 19N-20N BETWEEN 69W-73W. MODERATE MOISTURE IS IN THE
VICINITY ESPECIALLY NORTH OF THE ISLAND ASSOCIATED WITH AN UPPER
LEVEL TROUGH IN THE FAR WEST ATLC. MOISTURE ASSOCIATED WITH A
TROPICAL WAVE JUST EAST OF THE LESSER ANTILLES IS EXPECTED TO
REACH HISPANIOLA WITHIN 24 HOURS AND MAY INCREASE AFTERNOON
CONVECTION. A SECOND WAVE WILL BRING MORE MOISTURE LATER IN THE
WEEK.

ATLANTIC OCEAN...
DIFFLUENT FLOW ALOFT COVERS THE WEST ATLC AROUND AN UPPER LEVEL
LOW OVER FLORIDA SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS OVER
MUCH OF THE BAHAMAS FROM 22N-28N BETWEEN 74W-80W. A SECOND UPPER
TROUGH IS ALONG 29N71W TO 24N65W SUPPORTING A SURFACE TROUGH
ALONG 31N69W TO 24N65W. ISOLATED SHOWERS/THUNDERSTORMS ARE
WITHIN 220 NM EAST OF THE AXIS. BROAD UPPER RIDGING DOMINATES
THE REMAINDER OF THE CENTRAL AND EASTERN TROPICAL ATLC CENTERED
NEAR 23N28W. THIS UPPER RIDGE SUPPORTS BROAD SURFACE RIDGING
ANCHORED BY A 1025 MB HIGH NEAR 28N42W. MUCH OF THE EASTERN ATLC
IS ALSO COVERED BY A VERY STABLE SAHARAN AIR LAYER EXTENDING TO
ALMOST 45W.

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

$$
WALTON


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