[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 292334
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT JUN 29 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
2245 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 18N30W TO 7N29W MOVING WEST AT 10-15 KT.
THE WAVE IS ILL-DEFINED AT THE SURFACE...BUT ALIGNS WELL WITH A
700 MB TROUGH AXIS. DEEP CONVECTION IS CONSTRAINED TO THE ITCZ
REGION.

TROPICAL WAVE IS ALONG 18N61W TO 9N65W MOVING WNW NEAR 15 KT. A
WEAK 1011 MB SURFACE LOW IS ANALYZED ALONG THE WAVE AXIS NEAR
12N65W. THE WAVE LIES ON THE WEST SIDE OF A LARGE SURGE OF DEEP
LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY.
ISOLATED MODERATE CONVECTION IS FROM 12N-18N BETWEEN 56W-
64W...AND FROM 18N-24N BETWEEN 53W-58W. THIS ACTIVITY IS ALSO
BEING ENHANCED BY DIFFLUENT FLOW ALOFT AROUND AN UPPER LEVEL
TROUGH OVER THE EASTERN CARIBBEAN.

TROPICAL WAVE IS MOVING SLOWLY THROUGH THE WESTERN CARIBBEAN
ALONG 20N81W TO 10N81W MOVING WEST NEAR 5 KT. THE WAVE LIES
WITHIN A BROAD AREA OF ENHANCED MOISTURE OVER MUCH OF THE
WESTERN CARIBBEAN. SCATTERED MODERATE/STRONG CONVECTION IS
MAINLY EAST OF THE WAVE FROM 13N-20N BETWEEN 77W-81W. SIMILAR
ACTIVITY IS WEST OF THE AXIS FROM 10N-14N BETWEEN 81W-86W ACROSS
COSTA RICA AND PANAMA. SCATTERED MODERATE/STRONG CONVECTION IS
ALSO OVER WESTERN CUBA...BUT MAY BE MORE RELATED TO UPPER LEVEL
DYNAMICS.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE COAST OF GUINEA-BISSAU NEAR
12N16W TO 7N25W. THE ITCZ BEGINS NEAR 7N25W AND CONTINUES TO
3N39W. SCATTERED MODERATE CONVECTION IS WITHIN 45 NM EITHER SIDE
OF THE AXIS BETWEEN 17W-31W.

...DISCUSSION...

GULF OF MEXICO...
WEAK SURFACE RIDGING IS ACROSS THE SOUTHERN GULF OF MEXICO
PROVIDING LIGHT ANTI-CYCLONIC FLOW. PRIMARILY WEST WINDS COVER
THE NORTHERN GULF AROUND BROAD TROUGHING INCREASING UP TO 15 KT.
ALOFT...AN ELONGATED UPPER LOW IS OVER THE WESTERN GULF NEAR
25N93W. A LONGWAVE UPPER TROUGH COVERS MUCH OF THE EASTERN
CONUS...AND PROVIDES MOIST SOUTHWESTERLY FLOW ALOFT OVER THE NE
GULF. ISOLATED SHOWERS/THUNDERSTORMS ARE THROUGHOUT THE NE
GULF...WITH MORE SCATTERED ACTIVITY OVER THE SE GULF AND OVER
THE SOUTHERN HALF OF THE FLORIDA PENINSULA. WEAK SURFACE RIDGING
WILL REMAIN OVER THE SOUTHERN GULF AS BROAD TROUGHING CONTINUES
TO DOMINATE THE NORTHERN HALF. MOIST CONDITIONS WILL REMAIN OVER
MUCH OF THE EASTERN GULF AS THE UPPER TROUGH OVER THE EASTERN
CONUS STAYS MOSTLY STATIONARY AND THE UPPER LOW IN THE SW GULF
DRIFTS EAST FURTHER PROVIDING DIFFLUENT SOUTHWESTERLY FLOW ALOFT
OVER THE EASTERN GULF. MOISTURE FROM A TROPICAL WAVE IN THE
WESTERN CARIBBEAN WILL ALSO BRING MORE MOISTURE TO THE SE GULF.

CARIBBEAN SEA...
A TROPICAL WAVE IS MOVING THROUGH THE WESTERN CARIBBEAN ALONG
81W. IT IS HELPING ENHANCE SCATTERED SHOWERS/THUNDERSTORMS OVER
WESTERN CUBA AS WELL AS STRONGER SHOWERS OVER NICARAGUA AND
COSTA RICA. THE LARGEST AREA OF SHOWERS/THUNDERSTORMS IS EAST OF
THE WAVE AXIS. MODEL GUIDANCE IS INDICATING THAT AS THE WAVE
DRIFTS WEST MOISTURE AND PRECIPITATION WILL CONTINUE OVER MUCH
OF CENTRAL AMERICA INCREASING THE RISK FOR FLOODING. THE MONSOON
TROUGH ALSO EXTENDS THROUGH THE SW CARIBBEAN ALONG 11N85W 13N80W
11N73W. STRONG SHOWERS/THUNDERSTORMS COVER MUCH OF NORTHERN
COLOMBIA NEAR THE AXIS. ALOFT...UPPER LEVEL RIDGING IS OVER
CENTRAL AMERICA WHILE UPPER TROUGHING IS TO THE EAST AND ACROSS
CUBA. A SECOND LARGER UPPER TROUGH IS ALONG 68W DRAWING DRY AIR
OVER THE CENTRAL CARIBBEAN...BUT MOIST AIR OVER THE FAR EASTERN
CARIBBEAN NEAR A SECOND TROPICAL WAVE. ACTIVITY NEAR THIS WAVE
IS BEGINNING TO DIE DOWN SOME WITH ONLY A FEW
SHOWERS/THUNDERSTORMS STILL OCCURRING EAST OF 64W ACROSS THE
LESSER ANTILLES. EXCEPT FOR THE CYCLONIC FLOW NEAR THE TWO
WAVES...TRADEWIND FLOW OF 15-20 KT DOMINATES ELSEWHERE. EXPECT
BOTH WAVES TO CONTINUE MOVING WEST OVER THE NEXT 24 HOURS.

HISPANIOLA...
A FEW ISOLATED SHOWERS/THUNDERSTORMS ARE LOCATED OVER THE
CENTRAL PORTION OF HISPANIOLA FROM 18N-19N BETWEEN 70W-72W.
DRIER AIR IN THE AREA IS KEEPING CONVECTION TO A LOWER AMOUNT
TODAY. THIS WILL REMAIN THE CASE UNTIL A TROPICAL WAVE EAST OF
THE ISLAND REACHES THE DOMINICAN REPUBLIC BY MIDDAY TOMORROW.
INCREASED AFTERNOON CONVECTION WILL LIKELY OCCUR WITH THE
INCREASED MOISTURE.

ATLANTIC OCEAN...
BROAD SURFACE RIDGING COVERS THE WEST AND CENTRAL ATLC AROUND A
1029 MB HIGH NEAR 392N43W. SCATTERED SHOWERS/THUNDERSTORMS ARE
ACROSS MUCH OF THE BAHAMAS FROM 23N-30N BETWEEN 71W-80W
ASSOCIATED WITH A SHORTWAVE UPPER TROUGH ALONG 27N71W TO 25N79W.
AN UPPER LEVEL LOW IS TRYING TO FORM FARTHER EAST NEAR 25N63W
SUPPORTING A FEW ISOLATED SHOWERS IN THE VICINITY. IT IS
ASSOCIATED WITH A BROADER UPPER TROUGH AXIS THAT CONTINUES INTO
THE EASTERN CARIBBEAN AND IS PROVIDING DIFFLUENT FLOW ALOFT NEAR
A TROPICAL WAVE TO THE SOUTH. TO THE NORTH...A WEAK SURFACE
TROUGH IS ALONG 32N53W TO 29N56W. ISOLATED SHOWERS ARE UP TO 150
NM TO THE EAST. THE REMAINDER OF THE EASTERN ATLC IS ALSO
DOMINATED BY SURFACE RIDGING AROUND A 1032 MB HIGH JUST NORTH OF
THE AZORES ISLANDS. ALOFT...UPPER RIDGING IS ALONG 54W AND 27W
WITH ANOTHER UPPER LOW SANDWICHED BETWEEN NEAR 32N41W. THE LAST
VISIBLE SATELLITE IMAGES OF THE DAY INDICATE THAT A LARGE AREA
OF SAHARAN DUST EXTENDS FROM THE COAST OF AFRICA TO NEAR 50W
AROUND THE TROPICAL WAVE IN THE EASTERN ATLC.

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

$$
WALTON


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