[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 062343
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN MAY 06 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N13W 4N20W 1N32W EQ44W 1S49W.
SCATTERED MODERATE CONVECTION IS FROM 1N-5N BETWEEN 18W-22W.
SIMILAR ACTIVITY IS WITHIN 120 NM OF THE AXIS W OF 40W. A
POSSIBLE VERY WEAK LOW AMPLITUDE TROPICAL WAVE IS
APPROACHING 30W. THIS WEAK FEATURE MAY BE ENHANCING SOME
CONVECTION S OF THE EQUATOR.

...DISCUSSION...

GULF OF MEXICO...
ACTIVE WEATHER IS OCCURRING THIS EVENING OVER SOUTH AND CENTRAL
FLORIDA. DOPPLER RADAR SHOWS NUMEROUS TSTMS QUICKLY MOVING S
DOWN THE FL PENINSULA...MOSTLY FROM LAKE OKECHOBBEE SWD WHERE
TORNADO WARNINGS ARE IN EFFECT. THIS ACTIVITY IS BEING PRODUCED
BY UPPER ENERGY ASSOCIATED WITH A STRENGTHENING VERTICALLY
STACKED LOW PRES SYSTEM OFF THE CAROLINA COAST...MORE ON THIS IN
THE W ATLC SECTION. ANOTHER FACTOR IS AN ASSOCIATED BACK DOOR
COLD FRONT THAT EXTENDS FROM THE W ATLC ACROSS NE FLORIDA TO THE
FL PANHANDLE. A PRE-FRONTAL TROUGH LIES ABOUT 90 NM S OF THE
FRONT...CLEARLY SEEN ON BOTH SATELLITE AND RADAR. THESE
BOUNDARIES ARE ANTICIPATED TO PROGRESS THRU FL AND THE ERN GULF
ON MON. THE REMAINDER OF THE GULF IS UNDER THE INFLUENCE OF WEAK
UPPER RIDGING...HOWEVER THIS RIDGE IS MUCH MORE AMPLIFIED JUST N
OF THE REGION OVER THE CENTRAL U.S. A BROKEN SWATH OF MID-HIGH
LEVEL CLOUDS IS PUSHING ACROSS THE W AND CENTRAL GULF BETWEEN
88W-95W. AT THE SFC...THE COMBINATION OF STRONG HIGH PRES
RIDGING IN THE NORTHEAST STATES AND LOW PRES OVER MEXICO/S
CENTRAL U.S. IS PRODUCING SELY WINDS TO 20 KT IN THE WRN GULF.
LIGHTER E TO SE WINDS EXIST ELSEWHERE BUT STRONG NELY WINDS ARE
EXPECTED TO DEVELOP IN THE E GULF LATER TONIGHT AS THE LOW PRES
SYSTEM STRENGTHENS OFF THE SOUTHEAST U.S. COAST.

CARIBBEAN SEA...
AN UPPER LEVEL WEAKNESS OR INDUCED TROUGHING LIES ABOVE THE WRN
CARIB WHILE EXTENSIVE SWLY FLOW ALOFT COVERS THE CENTRAL AND ERN
...ON THE W PERIPHERY OF A SPRAWLING UPPER HIGH CENTERED E OF
THE REGION OVER THE TROPICAL ATLC. THIS UPPER PATTERN IS
CONFLUENT IN THE NW CARIB PROVIDING SINKING AIR LEADING TO
LITTLE ORGANIZED CLOUD COVER. WHILE THE EXTENSIVE SWLY REGIME IS
HELPING TO FLARE CONVECTION ALONG THE ITCZ OVER S COSTA
RICA...PANAMA AND COLOMBIA. DEBRIS CIRRUS IS BEING ADVECTED
AROUND THE RIDGE ACROSS THE MAJORITY OF THE CENTRAL AND ERN
CARIB. AT THE SFC...THE PRESSURE PATTERN IS FAIRLY WEAK DUE TO A
TROUGH OF LOW PRES LOCATED NE OF HISPANIOLA. SHIPS AND BUOYS ARE
REPORTING E TO NELY TRADES MOSTLY IN THE 10-15 KT RANGE EXCEPT
STRONGER WINDS TO 20 KT ACROSS THE SRN PORTION WHERE THE PRES
GRADIENT IS TYPICALLY TIGHTER. THESE LIGHT TO MODERATE WINDS
SHOULD CONTINUE FOR THE NEXT DAY OR TWO AS THE SUBTROPICAL RIDGE
GIVES WAY TO STRENGTHENING LOW PRES OVER THE W ATLC.

WESTERN ATLANTIC...
THE BIG STORY IS ASSOCIATED WITH A STRENGTHENING LOW PRES SYSTEM
OFF THE CAROLINA COASTLINE....ANALYZED 1009 MB NEAR 35N74W. A
BACK DOOR COLD FRONT IS PROGRESSING SWD FROM THE LOW TO NE
FLORIDA. THIS LOW HAS AN IMPRESSIVE LARGE CIRCULATION WITH
MULTIPLE BOUNDARIES ROTATING AROUND IT PRODUCING SCATTERED
SHOWERS N OF 28N W OF 70W. THE MAIN IMPACT IS THE STRONG WINDS
AS A VERY TIGHT PRES GRADIENT HAS SET UP BETWEEN THE LOW AND
STRONG HIGH PRES OVER THE ERN GREAT LAKES. SHIPS/BUOYS ARE
REPORTING NLY WINDS TO 40 KT NOT FAR OFF THE SE COAST. GLOBAL
MODELS ARE NOW IN PRETTY GOOD AGREEMENT SHOWING THE SYSTEM
STRENGTHENING FURTHER AS IT TAKES A LOOPING OR SLOW WWD MOTION
TOWARD THE SE COAST. SEVERAL MODELS ARE ALSO SHOWING THE SYSTEM
BECOMING LESS FRONTAL IN NATURE OVER THE NEXT COUPLE DAYS.
MARINE IMPACTS ARE EXPECTED TO BE SIGNIFICANT IN THE NW PORTION
OF THE AREA...REFER TO MIAHSFAT2 FOR DETAILS S OF 31N. FARTHER
E...A WEAK 1011 MB LOW LOCATED NEAR 28N61W IS PRODUCING
SCATTERED SHOWER ACTIVITY NE OF THE LOW FROM 26N-31N BETWEEN
55W-57W. A SFC TROUGH HANGS S/SW FROM THE LOW TOWARD THE NRN
COAST OF HISPANIOLA...DEFINED BY A WIND SHIFT.

CENTRAL AND EASTERN ATLANTIC...
STRONG AZORES HIGH IS IN CONTROL OF THE PATTERN ACROSS THE ATLC
E OF 55W. THIS HIGH IS PRODUCING A LARGE AREA OF MODERATE TO
FRESH TRADES...STRONGEST E OF 25W WHERE THE PRES GRADIENT IS
TIGHTENED DUE TO LOWER PRES OVER AFRICA. SCATTERED STRATOCUMULUS
COVER MUCH OF THE REGION...EXCEPT S OF 18N E OF 28W WHERE THIS
LOW-LEVEL CLOUD DECK IS ERODED BY SAHARAN DUST. IN THE UPPER
LEVELS...A RIDGE AXIS RUNS FROM AN UPPER HIGH IN THE DEEP
TROPICS TO THE AZORES ALONG 10N53W 22N45W 32N38W. THE UPPER
PATTERN THEN FOLDS INTO A BROAD TROUGH ANCHORED BY AN UPPER LOW
CENTERED ABOUT 300-350 NM W OF THE CANARY ISLANDS NEAR 29N23W.
OVERALL...THIS UPPER PATTERN IS NOT PRODUCING MUCH MORE THAN
PATCHES OF CIRRUS.

$$
CANGIALOSI







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