[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 171747
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT JAN 17 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
1745 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 6N11W ALONG 5N13W TO 4N17W WHERE THE ITCZ BEGINS AND
CONTINUES ALONG 4N30W TO 3N40W. ISOLATED MODERATE
CONVECTION ARE WITHIN 100 NM OF THE ITCZ/MONSOON TROUGH AXIS
BETWEEN 13W AND 30W.

...DISCUSSION...

GULF OF MEXICO...

SURFACE HIGH PRESSURE EXTENDS ACROSS THE EASTERN US AND INTO THE
GULF PROVIDING LIGHT ANTICYCLONIC FLOW MAINLY BETWEEN 5 AND 10
KT ACROSS THE BASIN. A WEAKNESS IN THE RIDGE IN THE FORM OF A
SURFACE TROUGH IS OVER THE CENTRAL GULF FROM 27N90W TO 22N88W.
SCATTERED SHOWERS ARE WITHIN 120 NM OF EITHER SIDE OF THE TROUGH
AXIS. OTHERWISE...FAIR WEATHER DOMINATES THE BASIN. IN THE UPPER
LEVELS...GENERALLY ZONAL FLOW IS OCCURRING ACROSS THE BASIN.
OVER THE NEXT 24 HOURS A TROUGH WILL MOVE ACROSS THE SE US AND
THE EXTREME NE GULF OF MEXICO. THIS WILL SUPPORT A COLD FRONT
THAT IS FORECAST TO MOVE ACROSS NORTHERN FL AND POSSIBLY
PORTIONS OF THE NE GULF. THE TROUGH OVER THE CENTRAL GULF IS
FORECAST TO REMAIN NEARLY STATIONARY WITH SHOWERS.

CARIBBEAN SEA...

BROAD UPPER RIDGING CONTINUES TO COVER THE CARIBBEAN ANCHORED
OVER SOUTH AMERICA AND EXTENDS INTO THE W ATLC. THIS RIDGE IS
INHIBITING ANY DEEP CONVECTION ACROSS THE BASIN. A TROUGH ACROSS
THE NW ATLANTIC ALONG 63W SUPPORTS A COLD FRONT THAT EXTENDS
ACROSS THE WESTERN ATLANTIC AND WESTERN CUBA WHERE IT
TRANSITIONS TO A STATIONARY FRONT THAT EXTENDS FROM 21N78W TO A
1016 MB SURFACE LOW NEAR 20N86W. SCATTERED SHOWERS ARE WITHIN
100 NM OF EITHER SIDE OF THE FRONT. ELSEWHERE ACROSS THE
CARIBBEAN...CLOUDY CONDITIONS AND ISOLATED SHOWERS ARE OVER
HISPANIOLA AND PUERTO RICO WELL AHEAD OF THE ATLANTIC COLD FRONT.
OVER THE NEXT 24 HOURS THE SURFACE LOW AND STATIONARY FRONT OVER
THE NW CARIBBEAN IS FORECAST TO DISSIPATE. MAINLY FAIR WEATHER
IS EXPECTED TO CONTINUE ACROSS THE BASIN THROUGH SUNDAY.

...HISPANIOLA...

ISOLATED TO SCATTERED SHOWERS ARE OCCURRING ACROSS THE ISLAND
AHEAD OF AN APPROACHING COLD FRONT IN THE WESTERN ATLANTIC. THE
TAIL END OF THIS COLD FRONT IS EXPECTED TO MOVE ACROSS THE
NORTHERN PORTIONS OF THE ISLAND TONIGHT AND WILL BE EAST OF THE
ISLAND BY SUNDAY AFTERNOON. AN ENHANCEMENT IN SHOWER ACTIVITY CAN
BE EXPECTED THROUGH TONIGHT WITH A DECREASE DURING THE DAY
SUNDAY BEHIND THE FRONT.

ATLANTIC OCEAN...

AN UPPER TROUGH ALONG 63W SUPPORTS A COLD FRONT THAT EXTENDS
FROM A NW ATLANTIC LOW PRESSURE SYSTEM TO 31N57W TO 22N70W TO
WESTERN CUBA NEAR 21N75W. SCATTERED SHOWERS ARE WITHIN 50 NM
AHEAD OF THE FRONT S OF 24N. WIDELY SCATTERED MODERATE
CONVECTION IS FROM 24N TO 31N BETWEEN 50W AND 60W. UPPER LEVEL
DIFFLUENCE AROUND THE BASE OF AN UPPER TROUGH ALONG 48W IS
SUPPORTING ISOLATED MODERATE CONVECTION FROM 4N TO 9N BETWEEN
42W AND 51W. ELSEWHERE...A 1036 MB SURFACE HIGH PRESSURE SYSTEM
CENTERED NEAR 34N27W DOMINATES THE CENTRAL AND EASTERN BASIN
WITH ANTICYCLONIC FLOW AND FAIR WEATHER. OVER THE NEXT 24 HOURS
A COLD FRONT WILL EXIT THE SE US. THE COLD FRONT CURRENTLY IN
THE WESTERN ATLANTIC WILL MOVE INTO THE CENTRAL ATLANTIC NEAR
30N50W TO THE VIRGIN ISLANDS.

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

$$
LATTO


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