Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 072102 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 402 PM EST SUN FEB 7 2016 .SYNOPSIS... A STRONG COASTAL LOW OFF THE SOUTH CAROLINA COAST WILL MOVE AWAY TONIGHT AND MONDAY. AN UPPER LEVEL DISTURBANCE AND COLD FRONT WILL CROSS THE REGION LATE MONDAY...FOLLOWED BY AND EXTENDED PERIOD OF BELOW NORMAL TEMPERATURES THROUGH THE WORK WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 330 PM SUNDAY... MSAS SHOWS A SUB-1000MB (~994MB) SURFACE LOW EAST OF MYRTLE BEACH THIS AFTERNOON...WITH FURTHER DEEPENING TO NEAR 980MB EAST OF THE OBX FORECAST TONIGHT AS AN UPPER LOW OVER THE SAVANNAH RIVER BASIN BEGINS TO LIFT NORTHEAST. PRECIP RATES...A PERIOD MIX OF RAIN...SNOW AND SLEET (AT TIMES ALL SLEET)...HAVE BEGUN TO DECREASE IN THE PAST HOUR OR SO AS AS THE LOW REACHES OUR LATITUDE. RAP SOUNDINGS INDICATE THE WEAK WARM NOSE HAS LIKELY ERODED...SO WHILE RATES HAVE FALLEN OFF...SOME SLEET AND SNOW WILL CONTINUE TO BE POSSIBLE AS THE PRECIP SHIELD STARTS TO DIMINISH FROM WEST TO EAST. NO ADDITIONAL ACCUMULATION SO EXPECTED...IN ADDITION TO THE QUARTER TO HALF INCH REPORTS ON SOME AREAS THAT IS. WE WILL CONTINUE THE WINTER WX ADVISORY THROUGH 6PM...THOUGH THIS MAY BE CANCELED EARLIER. OTHERWISE...WE`LL SEE FAIRLY RAPID CLEARING OF THE CIRRUS SHIELD AFTER MIDNIGHT...WITH OVERNIGHT LOWS EXPECTED TO DROP INTO THE UPPER 30S AND LOWER 30S UNDER SHORTWAVE RIDGING ALOFT AND LIGHT SURFACE WINDS. THERE MAY BE SOME BLACK ICE IN THE COASTAL PLAIN IF ROADS DO NOT DRY OUT PRIOR TO THE CLEARING...AND THIS IS SOMETHING THAT WILL BE MONITORED THIS EVENING. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... AS OF 330 PM SUNDAY... THERE SHORTWAVE RIDGE ALOFT BETWEEN THE DEPARTING UPPER WAVE AND ITS KICKER WAVE APPROACHING FROM THE WEST WILL QUICKLY GIVE WAVE TO A STRONG SHOT OF DCVA MONDAY AFTERNOON AND EVENING. A SOUTHERLY WIND...GUSTING TO 20-25KT BY MONDAY AFTERNOON...WILL PROVIDE A BRIEF PERIOD OF WARMING AND MOISTEN...YIELDING STEEP LOWER TROPOSPHERIC LOOSE RATES AND THE POTENTIAL FOR A BAND OF SHOWERS DURING THE AFTERNOON. FORECAST HIGHS IN THE UPPER 40S AND LOWER 50S WILL KEEP THIS ALL LIQUID DESPITE THE LAPSE RATES AND A PATTERN THAT OFTEN FAVORS SNOW SHOWERS. HOWEVER...A SECONDARY BAND OF RAIN THAT CHANGES TO SNOW IS STILL POSSIBLE LATE MONDAY EVENING AND OVERNIGHT AS AN ARCTIC FRONT SURGES ACROSS THE AREA AND A WAVE OF LOW PRESSURE DEVELOPS SOMEWHERE OVER SOUTHEAST VA (PER A LOOSE MODEL CONSENSUS). THE 12Z NAM AND GFS ARE DRIER THAN IN PREVIOUS RUNS...SO CONFIDENCE IN THIS SECOND BAND IS LOW AND POPS WILL BE LIMITED TO JUST SLIGHT OR LOW END CHANCE VALUES FROM THE TRIANGLE NORTHEAST. LOWS MONDAY NIGHT WILL BE IN THE UPPER 20S AND LOWER 30S AND COLD ADVECTION STARTS TO KICK IN BEHIND THE AFOREMENTIONED FRONT. && .LONG TERM /TUESDAY THROUGH SUNDAY/...
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AS OF 400 PM SUNDAY... COLD AND MAINLY DRY NORTHWEST FLOW...IN A HIGHLY AMPLIFIED PATTERN CHARACTERIZED BY A STRONG WESTERN NOAM RIDGE AND EASTERN NOAM TROUGH...WILL PREVAIL THROUGH THE UPCOMING WEEK...THOUGH AN EAST PACIFIC TROUGH WILL BRIEFLY FLATTEN THE RIDGE NEXT WEEKEND. ALTHOUGH MAINLY A DRY PATTERN...THERE STILL APPEARS TO BE A COUPLE OF OPPORTUNITIES FOR LIGHT PRECIPITATION OVER PORTIONS OF CENTRAL NC DURING THE PERIOD...ON TUE AND LATE FRI-FRI NIGHT. THE FIRST OPPORTUNITY WILL OCCUR AS THE EASTERN NOAM TROUGH REACHES MAXIMUM AMPLITUDE DOWN THE EAST COAST ON TUE...OWING TO THE AMPLIFICATION OF A SHORTWAVE TROUGH AXIS ACCOMPANYING A CIRCULATION (NOW OVER THE UPPER GREAT LAKES) INTO THE TROUGH BASE/ACROSS THE MIDDLE ATLANTIC STATES. WITH ASSOCIATED WEAK HEIGHT FALLS ALOFT AND AMIDST STEEP LAPSE RATES AS THE COLD UPEPR TROUGH PIVOTS EAST... ENHANCED INSTABILITY CLOUDINESS --AND A CHANCE OF SPRINKLES/ FLURRIES...OR WORST CASE A BRIEF RAIN/SNOW SHOWER ACROSS THE NORTHERN PIEDMONT-- WILL RESULT ON TUE. OF POTENTIALLY GREATER CONSEQUENCE...BUT STILL WITH LOW FORECAST CONFIDENCE GIVEN LARGER THAN AVERAGE MODEL SPREAD...THE EASTERN NOAM TROUGH WILL BRIEFLY RELAX AND ALLOW A BRIEF EPISODE OF LOW-MID LEVEL WAA ACCOMPANYING A CLIPPER-TYPE WAVE TO SPREAD FROM THE CENTRAL PLAINS THU EASTWARD TO THE CAROLINAS BY LATE FRI-FRI NIGHT. THIS MAY RESULT IN A BRIEF PERIOD OF LIGHT RAIN OR SNOW ACROSS OUR SOUTHERN COUNTIES CENTERED AROUND FRI EVENING. OTHERWISE...GUIDANCE HAS TRENDED COLDER THROUGHOUT THE PERIOD...WITH HIGHS IN THE 30S-40S AND LOWS IN THE TEENS AND 20S...COLDEST WED-THU AND AGAIN ON SUN.
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&& .AVIATION /19Z SUNDAY THROUGH FRIDAY/... AS OF 100 PM SUNDAY... WITH A A DEEPENING SURFACE LOW OFF THE S COAST...PRECIP CONTINUES TO SPREAD INLAND ACROSS THE NC COASTAL PLAIN. RAIN HAS BEEN MIXING WITH OR COMPLETELY CHANGING TO SLEET AND SNOW ALONG AN AXIS FROM KFAY TO KRWI. NEAR TERM MODELS SHOW THIS CONTINUING THROUGH 22Z OR SO BEFORE PRECIP ENDS FROM WEST TO EAST AND THE NORTHEASTERLY WINDS BECOME NORTHWESTERLY. CEILINGS HAVE ACTUALLY REMAINED ABOVE 2000 FT FOR THE MOST PART...AND VFR CONDITIONS HAVE EVEN BEEN PREDOMINATE AT MANY SITES. OUTSIDE OF THE HEAVIEST PRECIP...EXPECT THIS TREND TO CONTINUE THROUGH THIS EVENING AND OVERNIGHT. A FEW WIND GUSTS TO 25 KT OR SO WILL BE POSSIBLE THIS AFTERNOON AS THE LOW CONTINUES TO DEEPEN AND PASS BY THE NC COAST. SOME MVFR VSBYS ARE ALSO POSSIBLE FROM KFAY TOP KRWI LATE TONIGHT WHERE IT HAS BEEN PRECIPITATION ALL DAY...ALTHOUGH GUIDANCE DOESN`T SHOW MUCH REPORT AND CONFIDENCE IS LOW AT THIS POINT. A SOUTHWEST WIND WILL DEVELOP ON MONDAY AHEAD OF A STRONG DISTURBANCE DROPPING IN FROM THE NORTHWEST. WIND GUSTS NEAR 20KT AND SHOWERS WILL INCREASE DURING THE AFTERNOON HOURS. OUTLOOK...AFTER THE DISTURBANCE ON MONDAY PASSES BY...THE REMAINDER OF THE WEEK SHOULD BE MOSTLY VFR...WITH GUSTY NORTHWEST WINDS EACH DAY. && .RAH WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ042- 043-077-078-088-089. && $$ SYNOPSIS...SMITH NEAR TERM...SMITH SHORT TERM...SMITH LONG TERM...2 AVIATION...SMITH

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