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TROPICAL DEPRESSION THIRTEEN SPECIAL DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL132011
700 PM CDT THU SEP 01 2011
SATELLITE...SURFACE...AND NOAA RECONNAISSANCE AIRCRAFT DATA INDICATE
THAT THE LOW PRESSURE AREA OVER THE CENTRAL GULF OF MEXICO HAS
ACQUIRED A CLOSED CIRCULATION THAT IS DEFINED ENOUGH TO BE
CONSIDERED A TROPICAL DEPRESSION. HOWEVER...THE CENTRAL REGION
STILL CONSISTS OF A LARGE AREA OF LIGHT WINDS. THE AIRCRAFT DATA
AND BUOY OBSERVATIONS SUPPORT AN INITIAL INTENSITY OF 30 KT.
ALTHOUGH THERE IS WIND SHEAR OVER THE CYCLONE...AN UPPER-LEVEL
ANTICYCLONE IS FORECAST TO BUILD OVER THE GULF OF MEXICO DURING THE
NEXT DAY OR SO. THIS SHOULD PROVIDE A MORE FAVORABLE UPPER-LEVEL
ENVIRONMENT FOR STRENGTHENING. HOWEVER...SINCE THE CIRCULATION IS
LARGE ONLY GRADUAL STRENGTHENING IS ANTICIPATED. THE OFFICIAL
INTENSITY FORECAST FOLLOWS THIS REASONING AND IS CLOSE TO THE
SHIPS/LGEM GUIDANCE.
SINCE THE DEPRESSION IS IN ITS FORMATIVE STAGE THE INITIAL MOTION
IS HIGHLY UNCERTAIN. IN FACT...THE CENTER COULD REFORM WITHIN THE
LARGE CIRCULATION DURING THE NEXT 12-24 HOURS. THE DEPRESSION IS
CURRENTLY LOCATED TO THE SOUTH OF A MID/UPPER LEVEL RIDGE OVER THE
CENTRAL UNITED STATES. THE RIDGE IS FORECAST TO SLIDE EASTWARD AND
WEAKEN DURING THE NEXT 2-3 DAYS...LEAVING THE CYCLONE IN WEAK
STEERING FLOW. THE OFFICIAL FORECAST SHOWS A SLOW NORTHWESTWARD
MOTION DURING THE NEXT 24 HOURS...FOLLOWED BY A TURN TOWARD THE
NORTH AND NORTHEAST. THE NHC TRACK IS IN BEST AGREEMENT WITH THE
GFS AND ECMWF MODELS.
THE DEPRESSION IS EXPECTED TO MOVE VERY SLOWLY DURING THE NEXT 5
DAYS PROLONGING THE PERIOD OF TROPICAL STORM CONDITIONS AND HEAVY
RAINFALL OVER PORTIONS OF THE NORTHERN GULF COAST.
FORECAST POSITIONS AND MAX WINDS
INIT 02/0000Z 26.6N 91.4W 30 KT 35 MPH
12H 02/0600Z 27.5N 92.3W 35 KT 40 MPH
24H 02/1800Z 28.2N 92.6W 40 KT 45 MPH
36H 03/0600Z 28.7N 92.7W 45 KT 50 MPH
48H 03/1800Z 29.3N 92.6W 50 KT 60 MPH
72H 04/1800Z 30.1N 92.3W 40 KT 45 MPH...INLAND
96H 05/1800Z 31.1N 91.5W 30 KT 35 MPH...INLAND
120H 06/1800Z 32.0N 90.5W 25 KT 30 MPH...INLAND
$$
FORECASTER BROWN/AVILA--------------------------------------------------------------------------
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BULLETIN
TROPICAL DEPRESSION THIRTEEN SPECIAL ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL132011
700 PM CDT THU SEP 01 2011
...TROPICAL DEPRESSION FORMS OVER THE CENTRAL GULF OF MEXICO...
...TROPICAL STORM WARNINGS ISSUED FOR PORTIONS OF THE NORTHERN GULF
COAST...
SUMMARY OF 700 PM CDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...26.6N 91.4W
ABOUT 225 MI...360 KM SW OF THE MOUTH OF THE MISSISSIPPI RIVER
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...NW OR 315 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...
A TROPICAL STORM WARNING HAS BEEN ISSUED FOR THE COAST OF THE
NORTHERN GULF OF MEXICO FROM PASCAGOULA MISSISSIPPI WESTWARD TO
SABINE PASS TEXAS.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT...
A TROPICAL STORM WARNING IS IN EFFECT FOR...
* PASCAGOULA MISSISSIPPI WESTWARD TO SABINE PASS TEXAS
A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA...IN THIS CASE WITHIN
24 HOURS.
FOR STORM INFORMATION SPECIFIC TO YOUR AREA...INCLUDING POSSIBLE
INLAND WATCHES AND WARNINGS...PLEASE MONITOR PRODUCTS ISSUED BY
YOUR LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICE.
DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 700 PM CDT...0000 UTC...THE CENTER OF TROPICAL DEPRESSION
THIRTEEN WAS LOCATED NEAR LATITUDE 26.6 NORTH...LONGITUDE 91.4 WEST.
THE DEPRESSION IS MOVING TOWARD THE NORTHWEST NEAR 6 MPH...9 KM/H.
A SLOW NORTHWESTWARD MOTION IS FORECAST THROUGH FRIDAY...FOLLOWED
BY A TURN TOWARD THE NORTH FRIDAY NIGHT OR SATURDAY. ON THIS
TRACK...THE CENTER OF THE CYCLONE IS EXPECTED TO APPROACH THE COAST
OF SOUTHERN LOUISIANA ON SATURDAY.
MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/H...WITH HIGHER
GUSTS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 48 HOURS AND
THE DEPRESSION COULD BECOME A TROPICAL STORM ON FRIDAY.
THE ESTIMATED MINIMUM CENTRAL PRESSURE FROM A NOAA RECONNAISSANCE
AIRCRAFT WAS 1007 MB...29.74 INCHES.
HAZARDS AFFECTING LAND
----------------------
RAINFALL...THE DEPRESSION IS EXPECTED TO PRODUCE TOTAL RAIN
ACCUMULATIONS OF 10 TO 15 INCHES OVER SOUTHERN LOUISIANA...SOUTHERN
MISSISSIPPI...AND SOUTHERN ALABAMA THROUGH SUNDAY...WITH POSSIBLE
ISOLATED MAXIMUM AMOUNTS OF 20 INCHES.
STORM SURGE...A STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 1
TO 3 FEET ABOVE GROUND LEVEL ALONG THE NORTHERN GULF COAST IN AREAS
OF ONSHORE FLOW.
NEXT ADVISORY
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NEXT COMPLETE ADVISORY...1000 PM CDT.
$$
FORECASTER BROWN/AVILA 
***DO NOT USE THIS WEBSITE AS YOUR SOLE SOURCE OF WEATHER INFORMATION, ESPECIALLY WATCHES AND WARNINGS. THIS WEBSITE DELIVERS FOCUSED INFORMATION FOR A SPECIFIC GEOGRAPHIC AREA AND IS NOT INTENDED TO PROVIDE TIMELY WEATHER WARNING INFORMATION***
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