Tropical Storm MATTHEW

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TROPICAL STORM MATTHEW DISCUSSION NUMBER   8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152010
500 AM EDT SAT SEP 25 2010
 
SATELLITE IMAGERY SHOWS LITTLE CHANGE IN THE STRUCTURE OF MATTHEW
DURING THE PAST SEVERAL HOURS...WITH A LARGE AREA OF CONVECTION
WITH TOPS COLDER THAN -80C CONTINUING TO THE WEST AND SOUTHWEST OF
THE CENTER.  LA CEIBA HONDURAS RECENTLY REPORTED A PRESSURE OF
1002.7 MB...SUGGESTING THAT THE CENTRAL PRESSURE IS STILL BELOW
1000 MB.  BASED ON THESE FACTORS...THE INITIAL INTENSITY IS HELD AT
45 KT...WITH THOSE WINDS LIKELY OCCURRING OVER WATER TO THE NORTH
OF THE CENTER.
 
THE CENTER IS NOT EASY TO FIND...AND THE INITIAL MOTION IS A
SOMEWHAT UNCERTAIN 285/14.  THE TRACK FORECAST REASONING AGAIN
REMAINS UNCHANGED...AS A STRONG MID-LEVEL RIDGE OVER THE GULF OF
MEXICO WILL GENERALLY STEER MATTHEW WEST-NORTHWESTWARD FOR THE NEXT
36 HOURS OR SO.  BY THE TIME MATTHEW MOVES INTO GUATEMALA AND
EASTERN MEXICO...THE STEERING FLOW WILL WEAKEN AS THE RIDGE BREAKS
DOWN...AND A SLOW MOTION TOWARD THE WEST-NORTHWEST OR NORTHWEST IS
EXPECTED UNTIL DISSIPATION.  THE NEW TRACK FORECAST IS AGAIN SHIFTED
A LITTLE TO THE NORTH AND NOW LIES NEAR THE MIDDLE OF THE
GUIDANCE ENVELOPE.

MATTHEW COULD STRENGTHEN A LITTLE AS THE CENTER CROSSES THE GULF OF
HONDURAS...BUT IT IS UNLIKELY TO BE OVER WATER LONG ENOUGH FOR
SIGNIFICANT STRENGTHENING.  THE CYCLONE SHOULD WEAKEN STEADILY
AFTER LANDFALL IN BELIZE AND BECOME A REMNANT LOW BY 48 HR.  AFTER
72 HR...THE REMNANTS ARE EXPECTED TO BE ABSORBED INTO A LARGE
MONSOON LOW PRESSURE AREA FORECAST TO FORM OVER CENTRAL AMERICA AND
THE ADJACENT WATERS.

THE LARGEST THREAT FROM MATTHEW IS HEAVY RAINS.  IT SHOULD BE NOTED
THAT A HEAVY RAIN THREAT WILL CONTINUE AFTER MATTHEW DISSIPATES DUE
TO THE MONSOONAL FLOW ACROSS CENTRAL AMERICA.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      25/0900Z 15.7N  86.3W    45 KT
 12HR VT     25/1800Z 16.2N  88.0W    45 KT...OVER WATER
 24HR VT     26/0600Z 16.8N  89.8W    35 KT...INLAND
 36HR VT     26/1800Z 17.2N  90.8W    30 KT...INLAND
 48HR VT     27/0600Z 17.5N  91.4W    25 KT...POST-TROP/REMNT LOW
 72HR VT     28/0600Z 18.0N  92.0W    20 KT...POST-TROP/REMNT LOW
 96HR VT     29/0600Z...DISSIPATED
 
$$
FORECASTER BEVEN
 
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