Re: Eastern North Carolina Warnings and Reports
Posted by BobbiStorm on 9/29/2010, 4:09 pm
good discussion out of nws raleigh

A PSEUDO PREDECESSOR RAIN EVENT (PRE) IS ONGOING ACROSS THE
CAROLINAS AND VIRGINIA THIS AFTERNOON. RESEARCH FROM U OF ALBANY AND
OTHERS SUGGEST THIS IS MOST SIMILAR TO A SOUTHWESTERLY JET PRE ARCH
TYPE AND THE HEAVY RAIN ASSOCIATE WITH THIS FEATURE COMBINED WITH
HEAVY RAIN ON SUNDAY/MONDAY HAS RESULTED IN FLASH FLOODING ACROSS
THE SOUTHEAST NC COASTAL REGION.

LATEST GUIDANCE FROM NHC SUGGEST A COMPLICATED EVOLUTION OF TROPICAL
STORM NICOLE RESULTING IN AN EXTRATROPICAL TRANSITION DURING THE
NEXT 36 HOURS AS THE SYSTEM PUSHES NORTHEAST INTO THE ATLANTIC. NWP
GUIDANCE IS IN CLOSER AGREEMENT BUT STILL HAVING DIFFICULTY HANDLING
A LOW PRESSURE SYSTEM THAT DEVELOPS NORTH OF NICOLE OFF THE NE FL
AND GA COAST THIS EVENING. BOTH OF THESE LOW PRESSURE SYSTEMS ARE
LOCATED WITHIN A DEEP PLUME OF MOISTURE AKA AN ATMOSPHERIC RIVER
THAT EXTENDS SOUTH INTO THE W CARIBBEAN. RECENT SREF AND GFS RUNS
HAVE INDICATED THAT THE PW VALUES OVERNIGHT WILL BE 2-3 STANDARD
DEVIATIONS ABOVE NORMAL WITH A VERY STRONG SOUTHERLY COMPONENT OF
THE LOW LEVEL FLOW - INGREDIENTS NOTED BY GRUM AND OTHERS FOR
EXCESSIVE RAIN EVENTS.

LOTS OF MECHANISM TO GENERATE VERTICAL ASCENT TONIGHT WITH A DEEP
MID AND UPPER LEVEL LOW ACROSS AL/GA...THE RIGHT ENTRANCE REGION OF
A 110 KT JET ALOFT...A STRENGTHENING LOW LEVEL E/SE FLOW RIDING UP
AN OVER A MORE STABLE SFC BASED LAYER AS WELL FRONTOGENETICAL
FORCING NEAR THE W ADVANCING COASTAL FRONT. THE PLACEMENT OF THE
HEAVIEST RAIN WILL LARGELY BE DICTATED BY THE LOCATION OF THE
COASTAL FRONT WHICH WILL ALSO IMPACT THE AND THE TRACK OF THE
DEVELOPMENT SFC LOW. IN GENERAL THE HEAVIEST RAIN SHOULD FALL NEAR
AND ON THE COOL SIDE OF THE BOUNDARY.
88
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Eastern North Carolina Warnings and Reports - Tim_NC, 9/29/2010, 8:15 am
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