WTNT45 KNHC 232051
TCDAT5
TROPICAL STORM MATTHEW DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152010
500 PM EDT THU SEP 23 2010
 
AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT INVESTIGATING THE
CYCLONE FOUND 42-KT FLIGHT-LEVEL WINDS AT ABOUT 1500 FT IN THE
NORTHEAST QUADRANT ON ITS OUTBOUND LEG. THAT WIND SPEED WOULD
NORMALLY EQUATE TO ABOUT 34 KT AT THE SURFACE. ALSO...THERE WERE
SEVERAL BELIEVABLE SFMR SURFACE WINDS OF 35-37 KT IN THAT AREA.
SINCE THOSE WIND REPORTS...CONVECTIVE BANDING HAS CONTINUED TO
INCREASE AND BECOME BETTER ORGANIZED..AND THE DEPRESSION HAS BEEN
UPGRADED TO TROPICAL STORM MATTHEW.
 
THE INITIAL MOTION ESTIMATE IS 280/14. TROPICAL STORM MATTHEW IS
EXPECTED TO MOVE WEST TO WEST-NORTHWESTWARD FOR THE NEXT 48 HOURS
OR SO...AND PASS OVER OR NEAR THE NORTHERN COASTS OF NICARAGUA AND
HONDURAS IN 36-48 HOURS. AFTER THAT...THE GLOBAL MODELS DIFFER ON
THE TIMING OF THE WEAKENING OF THE SUBTROPICAL RIDGE OVER THE
NORTHWESTERN CARIBBEAN SEA AND THE GULF OF MEXICO. A STRONG
MID-LATITUDE TROUGH CURRENTLY OFF THE U.S. WEST COAST IS FORECAST
TO MOVE QUICKLY EASTWARD INTO THE CENTRAL U.S. BY DAY 3...THE
TROUGH IS FORECAST TO DIG SOUTHEASTWARD AND AMPLIFY INTO A LOW
PRESSURE SYSTEM OVER THE SOUTHEASTERN U.S. AND THE GULF OF MEXICO.
EROSION OF THE SUBTROPICAL RIDGE TO THE NORTH OF MATTHEW IS
EXPECTED TO CAUSE THE STEERING CURRENTS TO COLLAPSE ACROSS THE
NORTHWESTERN CARIBBEAN SEA AND THE YUCATAN PENINSULA. ALL OF THE
NHC MODELS ARE CONSISTENT ON THE EVOLUTION OF THIS SYNOPTIC
SCALE PATTERN...EXCEPT FOR THE TIMING. THE GFS...ECMWF...NOGAPS...
HWRF...AND GFDL MODELS KEEP THE LOW WEST OF 85W LONGITUDE BY 120
HOURS...WHEREAS THE UKMET IS MUCH MORE PROGRESSIVE AND MOVES THE
LARGE TROUGH EAST OF 80W. GIVEN THE USUAL SLOW MOVEMENT OF SUCH
A HIGH AMPLITUDE TROUGH...THE UKMET IS CONSIDERED AN OUTLIER MODEL
AT THIS TIME. AS A RESULT...THE OFFICIAL FORECAST TRACK IS A BLEND
OF THE GLOBAL AND REGIONAL MODELS...EXCLUDING THE UKMET SOLUTION...
AND IS JUST AN UPDATE OF THE PREVIOUS FORECAST TRACK.
 
STEADY INTENSIFICATION IS EXPECTED THROUGH 72 HOURS SINCE MATTHEW
WILL BE MOVING OVER 30C SSTS AND BENEATH A REGION OF UPPER-LEVEL
ANTICYCLONIC FLOW. MATTHEW IS EXPECTED TO MOVE OVER OR NEAR THE
NORTH COAST OF HONDURAS IN 36-48 HOURS...AND MOVE INLAND NEAR
BELIZE BY DAY 4. LAND INTERACTION WOULD DISRUPT THE INTENSIFICATION
PROCESS DESPITE THE OTHERWISE FAVORABLE ENVIRONMENTAL CONDITIONS.
HOWEVER...IF THE CYCLONE REMAINS OVER WATER...THEN MATTHEW COULD
EASILY REACH HURRICANE STRENGTH DURING THE NEXT 48 HOURS AND
BEYOND. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS
ADVISORY AND THE SHIPS/LGEM MODELS...AND IS BASED ON THE ASSUMPTION
THAT MATTHEW WILL MOVE INLAND AFTER 72 HOURS.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/2100Z 14.0N  76.9W    35 KT
 12HR VT     24/0600Z 14.4N  78.9W    40 KT
 24HR VT     24/1800Z 15.1N  81.7W    50 KT
 36HR VT     25/0600Z 15.6N  84.0W    60 KT...INLAND
 48HR VT     25/1800Z 16.2N  85.8W    60 KT...OVER WATER
 72HR VT     26/1800Z 17.1N  88.0W    70 KT
 96HR VT     27/1800Z 18.3N  88.4W    70 KT...INLAND
120HR VT     28/1800Z 19.5N  87.5W    70 KT...INLAND
 
$$
FORECASTER STEWART
 


WTNT45 KNHC 240258
TCDAT5
TROPICAL STORM MATTHEW DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152010
1100 PM EDT THU SEP 23 2010
 
THE OVERALL ORGANIZATION OF MATTHEW HAS CONTINUED TO GRADUALLY
IMPROVE THIS EVENING.  A BURST OF DEEP CONVECTION HAS RECENTLY
DEVELOPED OVER THE CENTER AND SEVERAL BROKEN BANDS OF THUNDERSTORMS
ARE SEEN AROUND THE PERIPHERY OF THE CIRCULATION.  THE LATEST
SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB ARE 45 AND 35
KT...RESPECTIVELY.  BASED ON THESE ESTIMATES THE INITIAL INTENSITY
IS SET AT 40 KT.
 
THE INITIAL MOTION ESTIMATE IS 275/15.  FOR THE NEXT 36-48 HOURS...
MATTHEW IS EXPECTED TO CONTINUE IN A WEST TO WEST-NORTHWEST
DIRECTION TO THE SOUTH OF A SUBTROPICAL RIDGE THAT EXTENDS FROM THE
ATLANTIC WESTWARD INTO THE SOUTHEASTERN UNITED STATES.  THE TRACK
GUIDANCE IS IN GOOD AGREEMENT DURING THAT TIME AND THERE IS FAIRLY
HIGH CONFIDENCE IN THAT PART OF THE FORECAST.  IN 2-3 DAYS...
THE WESTERN PORTION OF THE RIDGE IS EXPECTED TO WEAKEN AS A STRONG
MID-LATITUDE TROUGH MOVES INTO THE CENTRAL UNITED STATES. THIS
SHOULD RESULT IN A WEAKENING OF THE STEERING CURRENTS AND A
DECELERATION OF THE CYCLONE.  THEREAFTER...THE MODEL SOLUTIONS
DIVERGE SIGNIFICANTLY...WITH SEVERAL OF THEM SHOWING RATHER
COMPLEX SCENARIOS.  THE GFS...UKMET...AND ECMWF ALL MOVE MATTHEW
WELL INLAND OVER THE SOUTHERN PORTION OF THE YUCATAN PENINSULA IN
2-3 DAYS.  AFTER THAT TIME...THE GFS AND ECMWF ACTUALLY WEAKEN
MATTHEW...THEN DEVELOP A SECOND CYCLONE OVER THE NORTHWEST
CARIBBEAN SEA.  ON THE OTHER HAND...THE NOGAPS...GFDL....AND HWRF
KEEP MATTHEW AS THE PRIMARY SYSTEM AND SHOW IT TURNING NORTHWARD
ALONG THE CARIBBEAN COAST OF THE YUCATAN PENINSULA AT DAYS 4 AND 5. 
NEEDLESS TO SAY...THERE IS A MUCH HIGHER DEGREE OF UNCERTAINTY IN
THE 4 AND 5 DAY FORECASTS THAN NORMAL.  FOR NOW THE OFFICIAL
FORECAST HAS BEEN ADJUSTED CLOSER TO THE MULTI-MODEL
CONSENSUS...TVCN...AND IS WEST OF THE PREVIOUS FORECAST BEYOND 72
HOURS.
 
MATTHEW WILL BE IN AN ENVIRONMENT OF LIGHT TO MODERATE EASTERLY
SHEAR OVER WARM WATER DURING THE NEXT DAY OR SO.  THEREFORE...
STEADY STRENGTHENING IS PREDICTED AND THE OFFICIAL FORECAST IS
CLOSE TO THE SHIPS/LGEM GUIDANCE DURING THAT TIME.  AFTER 24
HOURS...THE INTENSITY FORECAST IS HIGHLY DEPENDENT ON LAND
INTERACTION.  THE NEW OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS
ADVISORY THROUGH 48 HOURS...ASSUMING THE CENTER STAYS OFFSHORE OF
HONDURAS.  THEREAFTER...THE INTENSITY FORECAST HAS BEEN ADJUSTED
DOWNWARD SINCE THE NEW TRACK FORECAST SHOWS MATTHEW OVER THE
YUCATAN PENINSULA AT 72-120 HOURS.
 
BASED ON THE NEW TRACK AND INTENSITY FORECAST...SOME CHANGES WERE
REQUIRED TO THE WATCHES AND WARNINGS.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/0300Z 14.0N  78.4W    40 KT
 12HR VT     24/1200Z 14.5N  80.5W    50 KT
 24HR VT     25/0000Z 15.1N  82.9W    65 KT
 36HR VT     25/1200Z 15.9N  85.1W    60 KT...INLAND
 48HR VT     26/0000Z 16.6N  87.1W    65 KT...OVER WATER
 72HR VT     27/0000Z 17.9N  89.2W    50 KT...INLAND
 96HR VT     28/0000Z 18.5N  89.5W    40 KT...INLAND
120HR VT     29/0000Z 19.0N  89.5W    35 KT...INLAND
 
$$
FORECASTER BROWN
 


WTNT45 KNHC 241457
TCDAT5
TROPICAL STORM MATTHEW DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152010
1100 AM EDT FRI SEP 24 2010
 
AN AIR FORCE PLANE INVESTIGATING MATTHEW THIS MORNING FOUND THAT THE
TROPICAL CYCLONE HAS NOT BECOME ANY STRONGER. EASTERLY SHEAR HAS
KEPT THE LOW-LEVEL CENTER NEAR THE NORTHEAST EDGE OF A ROUND BLOB
OF VERY DEEP CONVECTION AS INDICATED BY THE AIR FORCE PLANE AND
MICROWAVE DATA. SATELLITE INTENSITY ESTIMATES SUPPORT AN INITIAL
INTENSITY OF 45 KNOTS...BUT DATA FROM THE RECONNAISSANCE PLANE SO
FAR SUGGEST THAT THIS ESTIMATE COULD BE GENEROUS. MATTHEW ONLY HAS
12 HOURS OR LESS TO STRENGTHEN BEFORE LANDFALL...AND GIVEN THAT THE
ENVIRONMENT IS ONLY MARGINALLY FAVORABLE FOR INTENSIFICATION DUE TO
SHEAR...THE OFFICIAL FORECAST NO LONGER FORECAST MATTHEW TO BECOME
A HURRICANE.
 
THE CYCLONE HAS INCREASED ITS FORWARD SPEED AND THE BEST ESTIMATE OF
THE INITIAL MOTION IS TOWARD THE WEST OR 275 DEGREES AT 17 KNOTS.
MATTHEW IS EMBEDDED WITHIN A STRONG DEEP EASTERLY FLOW AND THERE IS
HIGH CONFIDENCE IN THE FORECAST THAT THE CYCLONE WILL CONTINUE
WESTWARD OVER CENTRAL AMERICA FOR THE NEXT DAY OR TWO.  BEYOND TWO
DAYS...MODELS SHOW DIFFERENT SCENARIOS AND THE FORECAST BECOMES
HIGHLY UNCERTAIN. THE MOST LIKELY SCENARIO IS THAT THE MID-LEVEL
CENTER CONTINUES WESTWARD AND DISSIPATES...WHILE THE LOW-LEVEL
CIRCULATION WEAKENS AND BECOMES PART OF A NEARLY STATIONARY BROAD
AREA OF LOW PRESSURE OVER CENTRAL AMERICA. SUCH A WEATHER PATTERN
WOULD LIKELY PRODUCE DANGEROUS TORRENTIAL RAINS IN CENTRAL AMERICA
OVER THE NEXT FEW DAYS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/1500Z 14.4N  82.2W    45 KT
 12HR VT     25/0000Z 14.6N  84.2W    35 KT...INLAND
 24HR VT     25/1200Z 15.4N  86.5W    30 KT...INLAND
 36HR VT     26/0000Z 16.0N  89.0W    30 KT...INLAND
 48HR VT     26/1200Z 17.0N  90.0W    25 KT...INLAND
 72HR VT     27/1200Z 18.0N  90.5W    20 KT...POST-TROP/REMNT LOW
 96HR VT     28/1200Z 18.5N  90.5W    20 KT...POST-TROP/REMNT LOW
120HR VT     29/1200Z 18.5N  90.5W    20 KT...POST-TROP/REMNT LOW
 
$$
FORECASTER AVILA
 


WTNT45 KNHC 242036
TCDAT5
TROPICAL STORM MATTHEW DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152010
500 PM EDT FRI SEP 24 2010
 
THE LATEST AIR FORCE RECONNAISSANCE PLANE IN THE AREA FIXED THE
CENTER OF MATTHEW AT 1717 UTC ABOUT 30 NMI EAST OF THE NORTHEAST
COAST OF NICARAGUA WITH A MINIMUM PRESSURE OF 998 MB AND WINDS
SUPPORTING AN INTENSITY OF 45 KNOTS. SINCE THEN...MATTHEW MOVED
WESTWARD AND THE CENTER CROSSED THE COAST OF NORTHEASTERN NICARAGUA
AND IS NOW LOCATED INLAND SOUTH OF PUERTO LEMPIRA HONDURAS. THE
CLOUD PATTERN IS STILL WELL ORGANIZED WITH NUMEROUS CYCLONICALLY
CURVED RAINBANDS TO THE NORTH AND VERY DEEP CONVECTION NEAR THE
CENTER. SINCE THE CENTER IS ALREADY OVER LAND...GRADUAL WEAKENING
SHOULD BEGIN.

AS THE CENTER OF THE CYCLONE MOVES WESTWARD OVER HONDURAS DURING THE
NEXT 12 TO 24 HOURS...A LARGE PORTION OF THE CIRCULATION WILL BE
OVER THE GULF OF HONDURAS...AND TROPICAL STORM FORCE WINDS THERE
WILL BE SLOW TO SUBSIDE.  THE WIND RADII HAVE BEEN EXPANDED IN THE
NORTHERN SEMICIRCLE BASED ON AIRCRAFT AND NOAA BUOY DATA. 
 
MATTHEW HAS DECREASED SOME IN FORWARD SPEED AND IS MOVING WESTWARD
ABOUT 13 KNOTS...WELL EMBEDDED IN THE EASTERLY FLOW SOUTH OF A
SUBTROPICAL HIGH. THIS PATTERN IS NOT EXPECTED TO CHANGE MUCH IN
THE SHORT TERM...SO THIS GENERAL MOTION WITH A DECREASE IN FORWARD
SPEED IS EXPECTED TO CONTINUE UNTIL DISSIPATION IN ABOUT 2 TO 3
DAYS.

FOR THE PAST FEW DAYS GLOBAL MODELS HAVE BEEN CONSISTENTLY DEPICTING
A TROPICAL CYCLONE IN THE NORTHWESTERN CARIBBEAN SEA TOWARD THE
MIDDLE OF NEXT WEEK. THE MOST RECENT RUNS INDICATE THAT ANY
DEVELOPMENT THERE WOULD LIKELY NOT HAVE CONTINUITY WITH MATTHEW...
BUT RATHER REPRESENT THE FORMATION A NEW TROPICAL CYCLONE.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/2100Z 14.7N  83.7W    40 KT
 12HR VT     25/0600Z 15.2N  85.6W    35 KT...INLAND
 24HR VT     25/1800Z 15.8N  88.0W    30 KT...INLAND
 36HR VT     26/0600Z 16.5N  90.0W    25 KT...INLAND
 48HR VT     26/1800Z 17.0N  91.0W    20 KT...POST-TROP/REMNT LOW
 72HR VT     27/1800Z 17.0N  91.0W    20 KT...POST-TROP/REMNT LOW
 96HR VT     28/1800Z...DISSIPATED
 
$$
FORECASTER AVILA
 


WTNT45 KNHC 250832
TCDAT5
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
 


WTNT45 KNHC 251444
TCDAT5
TROPICAL STORM MATTHEW DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152010
1100 AM EDT SAT SEP 25 2010
 
THE INNER CORE OF MATTHEW HAS BECOME DISRUPTED WHILE MOVING OVER THE
HIGH TERRAIN OF CENTRAL AMERICA. HOWEVER...THE CYCLONE HAS A BROAD
CIRCULATION WITH PLENTY OF DEEP CONVECTION.  THE AREA OF STRONGEST 
THUNDERSTORMS IS CURRENTLY OVER GUATEMALA AND SOUTHERN BELIZE. THE
LOW LEVEL CENTER...OR WHAT IS LEFT OF IT...IS VERY DIFFICULT TO
LOCATE...BUT SURFACE OBSERVATIONS FROM HONDURAS AND BELIZE INDICATE
THAT THE BROAD AREA OF LOW PRESSURE IS CENTERED JUST OFF THE NORTH
COAST OF WESTERN HONDURAS. MATTHEW IS STILL GENERATING TROPICAL
STORM FORCE WINDS NORTH OF THE CENTER...AS INDICATED BY THE STRONG
EASTERLY WINDS JUST ABOVE THE SURFACE REPORTED BY THE BELIZE RAOB
THIS MORNING. INITIAL INTENSITY IS 35 KNOTS BUT GIVEN THAT MOST OF
THE CIRCULATION IS EXPECTED TO REMAIN OVER LAND...WEAKENING IS
FORECAST.
 
THERE ARE NO INDICATIONS THAT MATTHEW IS SLOWING DOWN YET. THE
INITIAL MOTION IS TOWARD THE WEST-NORTHWEST OR 285 DEGREES AT 13
KNOTS. HOWEVER STEERING CURRENTS ARE FORECAST TO COLLAPSE AND THE
ENTIRE CIRCULATION SHOULD BEGIN TO DRIFT TOWARD THE WEST-NORTHWEST
DURING THE NEXT 12 TO 24 HOURS UNTIL DISSIPATION. MANY OF THE TRACK
MODELS KEEP MATTHEW OVER NORTHERN GUATEMALA OR EASTERN MEXICO WHERE
THE OFFICIAL FORECAST HAS MATTHEW DISSIPATING OR BECOMING A REMNANT
LOW.
 
WE MUST EMPHASIZE THAT THE LARGEST THREAT FROM MATTHEW IS HEAVY
RAINS. TORRENTIAL RAINS WILL CONTINUE AFTER MATTHEW DISSIPATES DUE
TO MOIST SOUTHWESTERLY FLOW SPREADING ACROSS CENTRAL AMERICA...WHICH
IS FORECAST TO PREVAIL FOR THE NEXT SEVERAL DAYS.
 
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      25/1500Z 16.2N  87.8W    35 KT
 12HR VT     26/0000Z 16.5N  89.5W    30 KT...INLAND
 24HR VT     26/1200Z 17.0N  90.5W    25 KT...INLAND
 36HR VT     27/0000Z 17.5N  91.5W    25 KT...INLAND
 48HR VT     27/1200Z 17.5N  91.5W    20 KT...POST-TROP/REMNT LOW
 72HR VT     28/1200Z...POST-TROP/REMNT LOW
 
$$
FORECASTER AVILA
 


WTNT45 KNHC 260233
TCDAT5
TROPICAL DEPRESSION MATTHEW DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152010
1000 PM CDT SAT SEP 25 2010
 
INFRARED IMAGERY SHOWS DEEP CONVECTION INCREASING AGAIN NEAR THE
CENTER OF MATTHEW TONIGHT.  THE INTENSITY IS HELD AT 30 KT BASED ON
A 25-KT 10-MINUTE WIND FROM CIUDAD DEL CARMEN MEXICO NORTH OF THE
CENTER AROUND 0000 UTC...AND THE CENTRAL PRESSURE OF 1001 MB IS
BASED ON AN OBSERVATION FROM TIKAL GUATEMALA AS THE CENTER PASSED
NEARBY.  GRADUAL WEAKENING IS EXPECTED AS THE CYCLONE WILL REMAIN
OVER LAND...WITH DISSIPATION EXPECTED BY 72 HOURS.
 
SATELLITE IMAGERY AND SURFACE OBSERVATIONS SUGGEST THAT MATTHEW IS
LOCATED FARTHER SOUTH AND WEST THAN PREVIOUSLY ESTIMATED...AND THE
INITIAL MOTION IS 285/12.  MATTHEW CONTINUES TO HAVE A LARGE
CIRCULATION EMBEDDED WITHIN A LARGER REGION OF CYCLONIC FLOW THAT
EXTENDS FROM THE EASTERN PACIFIC TO THE WESTERN CARIBBEAN. THE
CYCLONE WILL BE MOVING INTO A REGION OF WEAK STEERING FLOW IN
THE NEXT 12 TO 24 HOURS...AND THE FORWARD SPEED SHOULD SLOW
DRAMATICALLY.  BEYOND THAT TIME...A VERY SLOW SOUTHWARD OR
SOUTHEASTWARD DRIFT SEEMS LIKELY AS WHAT IS LEFT OF MATTHEW ROTATES
WITHIN THE LARGER CYCLONIC GYRE.  THE OFFICIAL FORECAST HAS BEEN
SHIFTED SOUTH AND WEST OF THE PREVIOUS ONE DUE TO THE INITIAL
POSITION AND MOTION AND A SOUTHWARD TREND IN MUCH OF THE GUIDANCE
FROM 24 TO 48 HOURS. 
 
TORRENTIAL RAINS WILL CONTINUE WITH MATTHEW AND ITS REMNANTS OVER
THE NEXT SEVERAL DAYS.  THERE WERE THREE OBSERVING SITES IN HONDURAS
AND GUATEMALA THAT REPORTED BETWEEN 6.1 AND 7.3 INCHES OF RAIN IN
THE 24-HOUR PERIOD ENDING AT 0000 UTC.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      26/0300Z 17.0N  91.0W    30 KT...INLAND
 12HR VT     26/1200Z 17.4N  92.1W    25 KT...INLAND
 24HR VT     27/0000Z 17.7N  92.6W    25 KT...POST-TROP/REMNT LOW
 36HR VT     27/1200Z 17.5N  92.6W    20 KT...POST-TROP/REMNT LOW
 48HR VT     28/0000Z 17.4N  92.5W    20 KT...POST-TROP/REMNT LOW
 72HR VT     29/0000Z...DISSIPATED
 
$$
FORECASTER BRENNAN
 


WTNT45 KNHC 260841
TCDAT5
TROPICAL DEPRESSION MATTHEW DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152010
400 AM CDT SUN SEP 26 2010
 
SURFACE OBSERVATIONS AND SATELLITE IMAGERY INDICATE THAT THE CENTER
OF MATTHEW HAS MOVED INTO EXTREME SOUTHEASTERN MEXICO...AND DEEP
CONVECTION HAS CONTINUED TO DEVELOP ACROSS SOUTHEASTERN MEXICO AND
NORTHERN PORTIONS OF CENTRAL AMERICA DURING THE PAST SEVERAL HOURS. 
NO WINDS HIGHER THAN ABOUT 15 KT HAVE BEEN REPORTED OVER LAND
RECENTLY...AND AN ASCAT PASS FROM AROUND 0340 UTC INDICATED WINDS
OF 20-25 KT OVER THE SOUTHEASTERN BAY OF CAMPECHE.  THE INTENSITY
IS THEREFORE LOWERED TO 25 KT.  VERY FEW OF THE DYNAMICAL MODELS
KEEP MATTHEW AS A DISTINCT AREA OF LOW PRESSURE FOR MUCH
LONGER...AND DISSIPATION IS EXPECTED BY 48 HOURS...IF NOT SOONER.

THE DEPRESSION IS SLOWING DOWN AND IS NOW MOVING 285 DEGREES AT 9
KT.  MATTHEW...OR WHAT IS LEFT OF IT...IS EXPECTED TO BECOME NEARLY
STATIONARY OVER THE ISTHMUS OF TEHUANTEPEC IN ABOUT 24-36 HOURS AS
IT BECOMES EMBEDDED WITHIN THE MIDDLE OF A MUCH LARGER CYCLONIC GYRE
THAT WILL EXTEND ACROSS THE NORTHWESTERN CARIBBEAN AND NORTHERN
CENTRAL AMERICA FOR THE NEXT FEW DAYS.  THE NEW TRACK FORECAST IS
AN UPDATE OF THE PREVIOUS ONE AND LIES NEAR THE CONSENSUS OF THE
GFS...ECMWF...GFDL...HWRF...AND NOGAPS.

EVEN THOUGH MATTHEW CONTINUES TO WEAKEN...TORRENTIAL RAINS WILL
CONTINUE WITH THE DEPRESSION AND ITS REMNANTS OVER THE NEXT SEVERAL
DAYS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      26/0900Z 17.3N  91.8W    25 KT
 12HR VT     26/1800Z 17.5N  92.7W    25 KT...INLAND
 24HR VT     27/0600Z 17.5N  93.1W    20 KT...POST-TROP/REMNT LOW
 36HR VT     27/1800Z 17.4N  93.0W    20 KT...POST-TROP/REMNT LOW
 48HR VT     28/0600Z...DISSIPATED
 
$$
FORECASTER BERG
 


WTNT45 KNHC 261435
TCDAT5
TROPICAL DEPRESSION MATTHEW DISCUSSION NUMBER  13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152010
1000 AM CDT SUN SEP 26 2010

VISIBLE/INFRARED SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE
THAT THE DEEP CONVECTION ASSOCIATED WITH THE SYSTEM HAS BECOME
DISORGANIZED AND THE MAXIMUM SUSTAINED WINDS ARE NO MORE THAN 20
KT.  MATTHEW HAS WEAKENED TO A REMNANT LOW AND THIS WILL BE THE
LAST ADVISORY.  THE SYSTEM HAS BEEN MOVING WESTWARD WITH A GRADUALLY
DECREASING FORWARD SPEED.  OVER THE NEXT DAY OR TWO...THE REMNANT
OF MATTHEW WILL LIKELY BECOME EMBEDDED WITHIN A BROAD CYCLONIC GYRE
EXTENDING FROM THE NORTHWESTERN CARIBBEAN WESTWARD ACROSS NORTHERN
CENTRAL AMERICA.  THE REMNANT IS EXPECTED TO TURN SLOWLY CLOCKWISE
WITHIN THE LARGER CYCLONIC CIRCULATION UNTIL DISSIPATION BY 36 TO
48 HOURS OR SOONER.
 
EVEN THOUGH THE LOW IS NO LONGER A TROPICAL CYCLONE THE SYSTEM...IN
CONJUNCTION WITH THE BROAD CYCLONIC GYRE...WILL CONTINUE TO PRODUCE
TORRENTIAL RAINS OVER PORTIONS OF EASTERN MEXICO AND CENTRAL
AMERICA OVER THE NEXT SEVERAL DAYS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      26/1500Z 17.4N  92.9W    20 KT
 12HR VT     27/0000Z 17.4N  93.4W    20 KT...POST-TROP/REMNT LOW
 24HR VT     27/1200Z 17.2N  93.5W    20 KT...POST-TROP/REMNT LOW
 36HR VT     28/0000Z 17.1N  93.3W    20 KT...POST-TROP/REMNT LOW
 48HR VT     28/1200Z...DISSIPATED
 
$$
FORECASTER PASCH
 


