AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC THU JUL 18 2013 .SYNOPSIS... HIGH PRESSURE CENTERED OVER THE OHIO VALLEY WILL MOVE OFF THE SOUTHEAST COAST ON FRIDAY. A COLD FRONT WILL APPROACH THE CAROLINAS OVER THE WEEKEND AND WILL REMAIN STALLED ACROSS THE REGION THROUGH EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 155 PM THURSDAY... WIDELY SCATTERED PULSE-TYPE SHOWERS AND TSTMS ONGOING ATTM... FAVORING OUR S AND SW ZONES THANKS TO THE DEEP E/NE FLOW AROUND THE LARGE ANTICYCLONE CENTERED OVER THE MID ATLANTIC STATES. THIS ACTIVITY IS MAINLY DIURNAL IN NATURE...SO LOOK FOR ONGOING ACTIVITY THIS EVENING TO DIMINISH AFTER SUNSET. GIVEN THE LIGHT FLOW...WEAK SHEAR...YET ABUNDANCE CAPE...MAIN IMPACTS WILL BE SLOW-MOVING DOWNPOURS AND FREQUENT CG LIGHTING. CAN`T RULE OUT AN ISOLD WIND GUST UP TO 45 MPH...BUT THIS WILL BE LIMITED TO THE TALLEST CELLS WITH THE DEEPEST CORES ALOFT. ONCE THE ACTIVITY DIMINISHES...THE REST OF THE NIGHT WILL FEATURE PC SKIES WITH SOME PATCHY FOG LATE. PERSISTENCE FOR LOWS...LOWER 70S. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 155 PM THURSDAY... THE RIDGE THAT HAS BEEN LOCATED TO OUR NORTH WILL SHIFT EAST OFF THE COAST AS A MID/UPR TROUGH BEGINS TO DEEPEN SOUTH ACROSS THE MIDWEST AND GREAT LAKES REGIONS. EVEN WHILE THIS IS OCCURRING...THE AIRMASS OVER OUR REGION WILL CHANGE LITTLE FROM TODAY...SO LOOK FOR ADDITIONAL ISOLATED TO SCATTERED SHOWERS/TSTMS TO FORM NEAR OR ALONG THE PIEDMONT TROUGH...FOLLOWED BY REDEVELOPMENT ALONG RESULTING OUTFLOWS. ONCE AGAIN THE MAIN IMPACTS WILL BE SLOW-MOVING DOWNPOURS...CG LIGHTNING...AND PERHAPS A FEW ISOLATED STRONG WIND GUSTS. ONE DIFFERENCE WORTH NOTING IS THE DEEP LAYER WIND DIRECTION WHICH ON FRIDAY WILL BE MORE FROM THE W/SW THROUGH H4...SO LOOK FOR STORM MOTION AND PROPAGATION TO BE MORE CLIMATOLOGICAL IN NATURE. PERSISTENCE FOR HIGHS FRIDAY...LOWER 90S. LITTLE CHANGE FRIDAY EVENING AND NIGHT...WITH PC SKIES AFTER TSTM ACTIVITY DIMINISHES. LOWS IN THE LOWER 70S. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 230 PM THURSDAY... SATURDAY THROUGH SATURDAY NIGHT: SHIFT TOWARDS A WETTER...MORE ACTIVE PATTERN IS STILL ON TRACK AS THE LONG WAVE UPPER TROF GRADUALLY AMPLIFIES AND TRANSLATES EAST THIS WEEKEND. AN APPROACHING FRONT WILL STILL BE OVER THE OHIO VALLEY ON SATURDAY...WITH MEAGER FORCING OF THE CLIMATOLOGICAL... WEAK AND DIURNALLY-DRIVEN VARIETY. WILL THUS MAINTAIN ONGOING SMALL CHANCE POPS. PLENTIFUL SUN WILL ALLOW HIGHS TO CLIMB INTO THE LOW 90S... WITH PERHAPS A FEW MID 90S READINGS IN THE EAST. MOISTURE WILL BEGIN REALLY SATURATING THE AIRMASS IN DEEPER SOUTHWEST FLOW AHEAD OF THE FRONT SATURDAY NIGHT INTO SUNDAY. THE FRONT WILL FALTER...PERHAPS STALL...OVER THE AREA WITH CORRESPONDING INCREASED CHANCES OF RAIN FROM SUNDAY AFTERNOON THROUGH AT LEAST TUESDAY...AND POSSIBLY ALL THE WAY THROUGH THURSDAY WHEN THE UPPER TROF AXIS EDGES EAST AND ALLOWS SOME DRYING IN WESTERLY FLOW. THERE IS LITTLE CONFIDENCE IN THE FRONTAL POSITION...MAKING THE TIMING AND DIFFERENTIATION OF LOCALES MORE PRONE TO INCREASED POPS LOW AT THIS POINT. WHAT CAN BE DETERMINED IS THAT THE AIRMASS WILL BE WELL-SATURATED AND UNSTABLE...THUS PERTURBATIONS IN THE MID LEVEL FLOW WILL BE ENOUGH TO EASILY INITIATE AND SUSTAIN CONVECTION. AT THIS POINT WILL HAVE GENERAL HIGH CHANCE POPS DURING THE AFTERNOONS...WITH A LULL OVERNIGHT...EACH DAY. HIGHS WILL BE A BIT BELOW NORMAL...HAMPERED BY INCREASED CLOUDINESS...AND MAINLY IN THE MID TO UPPER 80S. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 1205 PM THURSDAY... VFR CONDITIONS WILL PREVAIL THIS AFTERNOON AND EVENING WITH THE EXCEPTION BEING IN AND NEAR ISOLATED THUNDERSTORMS...WHERE FLT CONDITIONS MAY BRIEFLY LOWER TO MVFR. LATER TONIGHT THROUGH ABOUT 13Z FRIDAY...LOOK FOR PATCHY FOG WHICH MAY LOCALLY REDUCE VSBY DOWN TO 1-3 MILES. BEYOND THE 24 HOUR TAF PERIOD: OUTSIDE OF SOME EARLY MORNING FOG/STRATUS....VFR CONDITIONS SHOULD PREVAIL THROUGH SATURDAY WITH ONLY ISOLATED AFTERNOON STORMS. A SLOW MOVING COLD FRONT WILL MOVE INTO THE AREA FROM THE NORTHWEST ON SUNDAY...AND WILL LIKELY STALL OUT ACROSS EASTERN NC THROUGH EARLY NEXT WEEK...BRINGING UNSETTLED WEATHER IN THE FORM OF WIDESPREAD SHOWERS AND STORMS.
Posted on: Thu, 18 Jul 2013 20:51:16 +0000
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