[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 170558
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL.
205 AM EDT SUN JUL 17 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...SPECIAL FEATURE...

HURRICANE EMILY IS CENTERED NEAR 17.7N 81.2W OR ABOUT 415 MILES
MILES...670 KM... EAST SOUTHEAST OF COSUMEL MEXICO AND ABOUT 110
MILES...175 KM...SOUTH OF GRAND CAYMAN AT 17/0600 UTC MOVING WNW
18 KT. THE LATEST MINIMUM CENTRAL PRESSURE IS DOWN TO 943 MB AND
THE MAXIMUM SUSTAINED WIND SPEED IS AT THE THRESHOLD OF A
CATEGORY 4...130 KT WITH GUSTS TO 160 KT. PLEASE REFER TO THE
LATEST FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/
WTNT25 KNHC AND THE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT5/WTNT35 KNHC FOR MORE DETAILS.  EMILY CONTINUES TO
DISPLAY AN IMPRESSIVE SATELLITE APPEARANCE WITH ALL THE SIGNS OF
A DANGEROUSLY STRONG HURRICANE INCLUDING A WELL-DEFINED AND
CLEAR EYE...AND GOOD UPPER LEVEL OUTFLOW WITH A POLEWARD OUTFLOW
JET. LATEST SATELLITE IMAGERY SHOWS NUMEROUS CONVECTION WITH
EMILY IS WITHIN 60 NM OVER THE SW SEMICIRCLE AND WITHIN 200 NM
OVER THE NE SEMICIRCLE INCLUDING JAMAICA.  THIS ACTIVITY WILL
CONTINUE TO PRODUCE VERY HEAVY RAINFALL...STRONG WINDS...AND
POSSIBLE LIFE THREATENING FLOODING OVER JAMAICA AND THE CAYMAN
ISLANDS EARLY THIS MORNING....THEN EFFECTING THE YUCATAN
PENINSULA LATER TODAY.

...TROPICAL WAVES...

WESTERN ATLANTIC TROPICAL WAVE ALONG 21N S OF 18N MOVING W AT 15
KT. THE WAVE HAS A WELL DEFINED SWIRL OF LOW AND MID LEVEL
CLOUDS OVER THE CAPE VERDE ISLANDS. THIS WAVE REMAINS WELL
ORGANIZED FOR MID JULY. LITTLE CONVECTION IS NOTED.

CENTRAL ATLANTIC TROPICAL WAVE ALONG 30W/41W S OF 19N MOVING W
20 KT. THE WAVE IS EMBEDDED WITHIN A LARGE SURGE OF LOW LEVEL
EASTERLIES AND AFRICAN DUST/DRY AIR.  AS A RESULT...THE WAVE IS
MOVING FASTER THAN USUAL AND CONVECTION REMAINS SUPPRESSED N OF
THE ITCZ.  ISOLATED MODERATE CONVECTION FROM 6N-11N BETWEEN
41W-46W.

TROPICAL WAVE ALONG 55W/56W S OF 19N IS MOVING W 15 TO 20 KT.
THE WAVE IS INTERACTING WITH THE LEADING EDGE OF A STRONG LOW
LEVEL EASTERLY SURGE AND ASSOCIATED AFRICAN DUST/DRY AIR.
FURTHER NORTH... LOW LEVEL MOISTURE FROM THIS WAVE IS EXPECTED
TO ENTER THE WINDWARD ISLANDS SUN POSSIBLY PRODUCING INCREASING
SHOWERS/TSTMS.  SCATTERED MODERATE/ISOLATED STRONG CONVECTION
FROM EQ-10N BETWEEN 48W-58W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 12N17W 11N30W 10N40W 9N50W 9N60W
THEN ACROSS N PORTIONS OF S AMERICA. SCATTERED MODERATE
CONVECTION ALONG THE AXIS BETWEEN28W-34W.  SCATTERED
MODERATE/ISOLATED STRONG CONVECTION FROM 5N-13 N BETWEEN
45W-60W.

...DISCUSSION...

GULF OF MEXICO...
WEAKENING MID-UPPER LEVEL RIDGE EXTENDING FROM THE SE UNITED
STATES SW THROUGH 24N89W INTO A RETROGRADING UPPER LEVEL TROUGHT
OVER THE SE BAY OF CAMEACHE...A MIDDLE TO UPPER LEVEL TROUGH
EXTENDING SWD FROM THE CENTRAL UNITED STATES OVER TEXAS INTO N
CENTRAL MEXICO. AREAS OF ACTIVE CONVECTION IS NOTED ALONG  S BAY
OF CAMPECHE AND COAST OF YUCATAN S OF 20N.  ELSEWHERE...
DEEP-LAYERED MOISTURE REMAINS HIGH SUPPORTING ISOLATED TO WIDELY
SCATTERED SHOWERS AND TSTMS OVER THE OPEN WATERS OF THE GLFMEX
WITH TYPICAL AFTERNOON SHOWERS/TSTMS EXPECTED OVER FLORIDA.
HURRICANE EMILY IS FORECAST TO MOVE ACROSS THE YUCATAN PENINSULA
SUN AND ENTER THE GULF OF MEXICO ON MON. SOME OF THE UPPER LEVEL
OUTFLOW FROM EMILY IS ALREADY SPREADING OVER PORTIONS OF THE
EXTREME SE GULF AND FLORIDA.

CARIBBEAN SEA...
HURRICANE EMILY CONTINUES DOMINATES THE WEATHER OVER THE W
CARIBBEAN SEA WITH ASSOCIATED RAINBANDS EXTENDING OUTWARD UP TO
260 NM TO THE N OF THE CENTER.  AN AREA OF SCATTERED
MODERATED/ISOLATED STRONG CONVECTION IS ALSO NOTED FURTHER W
ALONG THE COAST OF SOUTHERN BELIZE MOVING INLAND. THIS ACTIVITY
IS IN ASSOCIATION WITH AN UPPER LOW OVER THE YUCATAN PENINSULA.
THE UPPER LOW WILL CONTINUE TO MOVE AWAY FROM EMILY THUS
RELAXING THE SHEAR AND ALLOWING IMPROVED POLEWARD OUTFLOW AND
FAVORABLE CONDITIONS FOR THE STRENGTHENING. THE UPPER LOW IS
FORECAST TO CONTINUE MOVING WESTWARD AND  CONTINUE TO WEAKEN. E
OF EMILY...UPPER LEVEL SUBSIDENCE AND RELATIVELY DRIER AIR ALOFT
IS BEGINNING TO PUSH WESTWARD BEHIND EMILY COURTESY OF A
RETROGRADING UPPER LOW OVER THE CENTRAL ATLC. THIS AIRMASS IS
EXPECTED TO CONTINUE SPREADING WESTWARD OVER THE E CARIBBEAN
PRODUCING MORE STABLE CONDITIONS.

ATLANTIC OCEAN...
THE PATTERN OVER THE ATLC FEATURES MIDDLE TO UPPER LEVEL RIDGE
OVER THE W ATLC WITH AXIS ALONG 73W/74W...THE MID-OCEANIC TROUGH
FROM 34N48W TO AN UPPER LOW NEAR 22N58W TO THE E CARIBBEAN NEAR
15N65W...AN ACCOMPANYING SURFACE TROUGH THAT FRACTURED FROM THE
TROPICAL WAVE LOCATED ALONG 55W/56W IS INTERACTING WITH THE
UPPER LEVEL TROUGH TO THE WEST. DIFFLUENT FLOW EAST OF THE
TROUGH HAS RESULTED IN SCATTERED MODERATE AND ISOLATED STRONG
CONVECTION WITHIN 140 NM E OF THE TROUGH AXIS FROM 22N-26N
BETWEEN 52W-54W. THE WEATHER OVER THE W ATLC REMAINS RELATIVELY
TRANQUIL. THE WAVE/SURFACE TROUGH ARE CURRENTLY EXPERIENCING
STRONG SHEAR WHICH IS LIMITING DEVELOPMENT AND FOCUSING THE
STRONGEST SHOWERS/TSTMS N OF 20N. E OF THE WAVE...A STRONG LOW
LEVEL ELY SURGE AND ASSOCIATED AFRICAN DUST IS OBSERVED MARCHING
WESTWARD ACROSS THE E AND CENTRAL ATLC WITH LEADING EDGE
CURRENTLY NEAR 52W.  THE RELATIVELY DRY/STABLE AIR WITHIN THIS
SURGE IS LIMITING DEEP CONVECTION TO THE ITCZ.

$$
JP/DB








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