11 PM (from NexLab, can't get in to NHC)
Posted by cypresstx on 10/6/2016, 11:08 pm

HURRICANE MATTHEW DISCUSSION NUMBER  36  
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142016  
1100 PM EDT THU OCT 06 2016  
 
THE SATELLITE APPEARANCE OF MATTHEW HAS IMPROVED DURING THE PAST  
SEVERAL HOURS, WITH AN EYE EMBEDDED WITHIN A MORE CIRCULAR CENTRAL  
DENSE OVERCAST AND AN INCREASE IN THE OUTER BANDING.  REPORTS FROM  
A NOAA HURRICANE HUNTER AIRCRAFT AND COASTAL RADAR DATA SHOW THE  
PRESENCE OF CENTRIC EYEWALLS WITH DIAMETERS OF ABOUT 8 AND 60 N MI  
RESPECTIVELY.  THE NOAA AIRCRAFT EARLIER REPORTED A MINIMUM PRESSURE  
OF 937 MB, AND AN AIR FORCE RESERVE HURRICANE HUNTER JUST REPORTED  
ESTIMATED SURFACE WINDS OF 109 KT FROM THE SFMR AND A PRESSURE OF  
939 MB. BASED ON THESE DATA, THE INITIAL INTENSITY IS 115 KT.  
 
THE INITIAL MOTION IS 325/11 KT. FOR THE NEXT 24-48 HOURS, MATTHEW  
SHOULD MOVE AROUND THE WESTERN END OF THE SUBTROPICAL RIDGE, WITH  
THE MOTION GRADUALLY TURNING NORTHWARD AND THEN NORTHEASTWARD.  
DURING THIS TIME, THE CENTER OF THE GUIDANCE ENVELOPE AND THE  
VARIOUS CONSENSUS MODELS HAVE SHIFTED A LITTLE TO THE EAST. HOWEVER,  
THE ECMWF, GFS, AND UKMET CONTINUE TO SUGGEST THE POSSIBILITY OF THE  
HURRICANE MAKING LANDFALL IN FLORIDA AND THEN MOVING NEAR THE COASTS  
OF GEORGIA AND SOUTH CAROLINA.  THIS PART OF THE FORECAST IS NUDGED  
A LITTLE TO THE EAST AND LIES BETWEEN THE MODEL CONSENSUS AND THE  
PREVIOUS FORECAST. AFTER 48 HOURS, A MID- TO UPPER-LEVEL RIDGE IS  
FORECAST TO BUILD NORTH AND WEST OF MATTHEW, AND THE TRACK GUIDANCE  
FORECASTS A SOUTHEASTERLY TO SOUTHERLY MOTION IN RESPONSE. WHILE  
THERE IS STILL A LARGE SPREAD, THE GFS, ECMWF, AND UKMET ARE IN  
BETTER AGREEMENT THAT MATTHEW SHOULD MOVE SOUTH BETWEEN THE RIDGE  
AND HURRICANE NICOLE TO THE EAST.  THIS PART OF THE FORECAST FOLLOWS  
THIS GUIDANCE AND LIES BETWEEN THE GFS AND ECMWF.  
 
DURING THE NEXT 12-24 HOURS, MATTHEW WILL LIKELY WEAKEN A LITTLE AS  
IT UNDERGOES AN EYEWALL REPLACEMENT CYCLE.  AFTER THAT TIME, IT IS  
EXPECTED TO ENCOUNTER STRONG SOUTHWESTERLY VERTICAL SHEAR, AND LATER  
IN THE FORECAST PERIOD DRY AIR IS LIKELY TO ENTRAIN INTO THE  
CYCLONE.  THIS COMBINATION SHOULD CAUSE STEADY WEAKENING, AND  
MATTHEW IS FORECAST TO DROP BELOW HURRICANE STRENGTH BY 72 HOURS.  
THE NEW INTENSITY FORECAST IS IN BEST AGREEMENT WITH THE SHIPS  
MODEL.  
 
KEY MESSAGES:  
 
1.  MATTHEW IS LIKELY TO PRODUCE DEVASTATING IMPACTS FROM STORM  
SURGE, EXTREME WINDS, AND HEAVY RAINS IN THE NORTHWESTERN BAHAMAS  
TODAY, AND ALONG EXTENSIVE PORTIONS OF THE EAST COAST OF FLORIDA  
TONIGHT.  
 
2.  EVACUATIONS ARE NOT JUST A COASTAL EVENT.  STRONG WINDS WILL  
OCCUR WELL INLAND FROM THE COAST, AND RESIDENTS OF MOBILE  
HOMES UNDER EVACUATION ORDERS ARE URGED TO HEED THOSE ORDERS.  
 
3.  HURRICANE WINDS INCREASE VERY RAPIDLY WITH HEIGHT, AND RESIDENTS  
OF HIGH-RISE BUILDINGS ARE AT PARTICULAR RISK OF STRONG WINDS. WINDS  
AT THE TOP OF A 30-STORY BUILDING WILL AVERAGE ONE SAFFIR-SIMPSON  
CATEGORY HIGHER THAN THE WINDS NEAR THE SURFACE.  
 
4.  WHEN A HURRICANE IS FORECAST TO TAKE A TRACK ROUGHLY PARALLEL TO  
A COASTLINE, AS MATTHEW IS FORECAST TO DO FROM FLORIDA THROUGH SOUTH  
CAROLINA, IT BECOMES VERY DIFFICULT TO SPECIFY IMPACTS AT ANY ONE  
LOCATION.  ONLY A SMALL DEVIATION OF THE TRACK TO THE LEFT OF THE  
NHC FORECAST COULD BRING THE CORE OF A MAJOR HURRICANE ONSHORE  
WITHIN THE HURRICANE WARNING AREA IN FLORIDA AND GEORGIA.  MODEST  
DEVIATIONS TO THE RIGHT COULD KEEP MUCH OF THE HURRICANE-FORCE WINDS  
OFFSHORE.  SIMILARLY LARGE VARIATIONS IN IMPACTS ARE POSSIBLE IN THE  
HURRICANE WATCH AND WARNING AREAS IN NORTHEAST GEORGIA AND SOUTH  
CAROLINA.  
 
5.  THE NATIONAL HURRICANE CENTER IS ISSUING POTENTIAL STORM SURGE  
FLOODING MAPS, AND PROTOTYPE STORM SURGE WATCH/WARNING GRAPHICS FOR  
MATTHEW.  IT IS IMPORTANT TO REMEMBER THAT THE POTENTIAL STORM SURGE  
FLOODING MAP DOES NOT REPRESENT A FORECAST OF EXPECTED INUNDATION,  
BUT RATHER DEPICTS A REASONABLE WORST-CASE SCENARIO -- THE AMOUNT OF  
INUNDATION THAT HAS A 10 PERCENT CHANCE OF BEING EXCEEDED.  
 
FORECAST POSITIONS AND MAX WINDS  
 
INIT  07/0300Z 27.1N  79.2W  115 KT 130 MPH  
12H  07/1200Z 28.5N  80.2W  110 KT 125 MPH  
24H  08/0000Z 30.3N  80.8W  105 KT 120 MPH  
36H  08/1200Z 31.8N  80.2W   90 KT 105 MPH  
48H  09/0000Z 32.6N  78.7W   75 KT  85 MPH  
72H  10/0000Z 31.5N  75.5W   60 KT  70 MPH  
96H  11/0000Z 29.0N  75.5W   50 KT  60 MPH  
120H  12/0000Z 27.0N  77.0W   40 KT  45 MPH  
 
 
FORECASTER BEVEN  
204
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11 PM (from NexLab, can't get in to NHC) - cypresstx, 10/6/2016, 11:08 pm
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