138 
FXUS62 KILM 191914
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
314 PM EDT TUE MAR 19 2013

.SYNOPSIS...
AN ARCTIC COLD FRONT WILL MOVE ACROSS THE CAROLINAS WEDNESDAY
NIGHT. WELL-BELOW NORMAL TEMPERATURES ARE EXPECTED THE LATTER HALF
OF THE WEEK. RAIN CHANCES WILL INCREASE THIS WEEKEND INTO EARLY
NEXT WEEK AS A STORM SYSTEM MOVES UP THE MISSISSIPPI VALLEY WHILE
A COASTAL TROUGH DEVELOPS ALONG THE COAST.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 PM TUESDAY...COLD FRONT PUSHING FARTHER OFFSHORE AND 
TAKING CLOUDS ALONG WITH IT. COLD AIR ADVECTION IN ITS WAKE TO 
MAINTAIN STRENGTH THROUGH 00Z BEFORE WEAKENING AT 06Z AND TURNING 
NEUTRAL TO POSSIBLY WEAKLY WARM OVER FAR SRN ZONES BY END OF 
PERIOD/12Z. WEAK 8S-1 VORT MAX ALSO SLIDING BY VERY LATE IN THE 
PERIOD AND GUIDANCE SHOWING A LITTLE BIT OF CLOUD COVER ASSOC WITH 
THIS FEATURE. AXIS OF HIGH DOES NOT BUILD IN TIL JUST BEYOND THE PD 
KEEPING A FEW MPH OF WINDS IN THE FCST AND PREVENTING IDEAL RAD 
COOLING AS WILL ANY OF THE POSSIBLY OVERFORECAST CLOUDS INDICATED. 
EITHER WAY FAIRLY MODEL GUIDANCE SHOWING GOOD AGREEMENT IN LOWS 
GENERALLY MID TO UPPER 30S AND 40 NR COAST. FROST...IF ANY...TOO 
PATCHY AND SHORT LIVED AT THIS POINT IN TIME TO WARRANT BEING IN 
FCST UNLESS FUTURE SHIFTS DEEM COLDER TEMPS AND/OR LIGHTER WINDS IN 
THE OFFERING. 

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 PM TUESDAY...UNCHARACTERISTICALLY COLD WEATHER FOR MARCH
WILL OCCUR AS A STRONG UPPER LEVEL LOW JUST NORTH OF THE GREAT
LAKES MAINTAINS A LONGWAVE TROUGH OVER THE EASTERN UNITED STATES.

A SOUTHERN STREAM SHORTWAVE GETTING INGESTED INTO THE BIG EAST
COAST UPPER TROUGH WILL BRING A LOAD OF MID AND UPPER LEVEL
PACIFIC MOISTURE ACROSS THE EASTERN CAROLINAS TOMORROW. THIS WILL
LEAD TO MOSTLY CLOUDY SKIES AND PERHAPS SNOW VIRGA ALOFT AS
RESPECTABLE ISENTROPIC LIFT BETWEEN 600-450 MB DEVELOPS DURING THE
EARLY AFTERNOON. EXTREMELY DRY AIR WITHIN THE DEEP SUB-CLOUD
LAYER SHOULD PREVENT ANY OF THIS PRECIPITATION FROM MAKING IT TO
THE GROUND AS DEWPOINT DEPRESSIONS AS LARGE AS 55 DEGREES F AT
900 MB MAY EXIST IF 12Z MODEL CONSENSUS IS CORRECT. SOME LATE-DAY
SUN IS POSSIBLE INLAND...BUT OVERALL LACK OF INSOLATION SHOULD
LEAD TO WELL-BELOW NORMAL HIGHS WITH 56-61 EXPECTED NORTH TO
SOUTH.

A SURFACE COLD FRONT ACCOMPANYING THE UPPER TROUGH WILL PUSH
THROUGH THE AREA WEDNESDAY NIGHT AS SKIES BECOME CLEAR. LIGHT
WINDS DURING THE EVENING WILL KICK BACK UP TO 5-10 MPH IN THE
POST-FRONTAL COLD ADVECTION WITH LOWS IN THE MID 30S INLAND AND
UPPER 30S AT THE COAST. THE NASTY ARCTIC AIR ARRIVES DURING THE
DAY THURSDAY WITH 1000-500 MB THICKNESSES FALLING AS LOW AS 529
DAM ACROSS SE NORTH CAROLINA...ACCOMPANIED BY 850 MB TEMPERATURES
PLUNGING TO -8C. THESE ARE AMONG THE 4 OR 5 COLDEST READINGS OF
THIS ENTIRE WINTER! EVEN WITH FULL SUNSHINE HIGHS WILL STRUGGLE
INTO THE LOW TO MID 50S WITH A GUSTY NORTHWEST BREEZE 15-20 MPH. 

THE REALLY TROUBLESOME NIGHT WILL BE THURSDAY NIGHT AS WINDS WILL
DIMINISH WITH THE ANOMALOUSLY COLD ARCTIC AIRMASS STILL PRESENT.
GFS AND NAM MOS MIGHT BE A TOUCH TOO COLD...BUT SUB-FREEZING
TEMPERATURES OF 27-31 APPEAR LIKELY ALL THE WAY DOWN TO THE
COAST. THE OFFICIAL 2013 GROWING SEASON HAS BEEN DETERMINED TO
START FOR OUR AREA THURSDAY...SO EXPECT THE ISSUANCE OF A FREEZE
WATCH PERHAPS TOMORROW FOR THURSDAY NIGHT. WE WILL ACTUALLY BE
WITHIN A COUPLE DEGREES OF RECORDS FOR THURSDAY NIGHTS...

LOW TEMPERATURE RECORDS FOR THURSDAY NIGHT (FRI MORNING) MARCH 21:

WILMINGTON     27 IN 1885
FLORENCE       26 IN 1965
MYRTLE BEACH   28 IN 1956

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 300 PM TUESDAY...MANY OF US WILL BE ASKING, "IS IT JANUARY OR 
MARCH"...AS A DEEP-WINTER-LIKE PATTERN TAKES HOLD THROUGH EARLY NEXT 
WEEK WITH WELL BELOW NORMAL TEMPS AND UNSETTLED CONDITIONS.

LARGE UPPER TROUGH SLOWLY WEAKENS FRIDAY IN RESPONSE TO AN UPPER LOW 
DROPPING INTO THE MTN STATES AND BOWLING ACROSS THE MIDDLE OF THE 
COUNTRY. FRIDAY WILL BE MOSTLY DRY THANKS TO HIGH PRESSURE RIDGING 
DOWN FROM THE NW. THIS WILL HELP SUPPRESS MOST MOISTURE TO THE 
SOUTH...BUT MAX TEMPS WILL STILL STRUGGLE ONLY INTO THE MID/UPPER 
50S...MORE TYPICAL OF JANUARY THAN LATE MARCH. LOWS FRIDAY NIGHT 
WILL FALL INTO THE MID/UPPER 30S WHILE CLOUD COVER INCREASES FROM 
THE SOUTH.

STILL QUESTIONS INTO THE EXTENDED DUE TO MODEL FLUCTUATIONS AND 
TIMING ISSUES...BUT IT APPEARS A COLD AND WET WKND/EARLY WEEK IS IN 
STORE FOR THE CAROLINAS. WARM FRONT/TROUGH WILL LIFT SLOWLY NORTH 
DURING SATURDAY...WITH INCREASINGLY MOIST ISENTROPIC LIFT 
OVERRUNNING THE COLD DOME OF HIGH PRESSURE WHICH WILL BEGIN TO WEDGE 
DOWN THE COAST. WHILE GFS BRINGS RAIN INTO THE AREA SATURDAY...THE 
WPC FAVORED ECMWF AND ITS ENSEMBLES KEEP MUCH OF SATURDAY DRY. WILL 
HEAD IN THIS DIRECTION BASED OFF SLOW ADVECTION OF THE THETA-E 
RIDGE. THIS WARM FRONT LIFTS NORTH AHEAD OF SURFACE CYCLOGENESIS 
BENEATH THE EASTWARD MOVING UPPER LOW. ALL EXTENDED GUIDANCE NOW 
SUPPORTS A MILLER-B TYPE SETUP...WITH A SURFACE LOW DEVELOPING ALONG 
THE COAST SUNDAY WHILE THE MID-WEST LOW FILLS. DEEP/NEGATIVELY 
TILTED UPPER TROUGH SUPPORTS THIS AS WELL...SO EXPECT A COASTAL LOW 
TO MOVE BASICALLY RIGHT ALONG THE COAST SUNDAY INTO MONDAY...FURTHER 
ENHANCING THE RAINFALL ALREADY ONGOING DUE TO THE INCREASED 
ISENTROPIC LIFT. THE POTENTIAL IS THERE FOR A SIGNIFICANT RAINFALL 
AS WELL...AND WPC PAINTS 1-1.5 INCHES OVER THE AREA. WILL CARRY HIGH 
CHC POP SUN-MON WITH TEMPS THROUGH MONDAY BEING VERY MUCH BELOW 
CLIMO...LIKELY AVERAGING A DEPARTURE OF -10 TO -15 DEGREES FOR MAX 
TEMPS.

COLD FRONT CROSSES MONDAY...BUT LITTLE CAA BEHIND THIS SO TEMPS WILL 
ACTUALLY RECOVER FOR THE EARLY PART OF NEXT WEEK WITH A MUCH DRIER 
AIRMASS IN PLACE...BUT STILL REMAIN WELL BELOW NORMAL...AND THE CPC 
6-10 DAY TEMPERATURE GRAPHIC IS QUITE CHILLING...NO PUN 
INTENDED...WITH 90% CHANCE FOR BELOW NORMAL ACROSS MOST OF THE 
SE/MID-ATLANTIC.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AS OF 18Z...LOW CLOUDS HAVE SCATTERED...AND THE CIRRUS WILL BE 
OFFSHORE SHORTLY. HIGH CONFIDENCE FOR VFR CONDITIONS THROUGH THE 
FORECAST PERIOD WITH HIGH PRESSURE BUILDING IN. WEST NORTHWEST WINDS 
AT 10-15 KTS WILL CONTINUE THROUGH THE AFTERNOON HOURS...DIMINISHING 
OVERNIGHT. HIGH LEVEL MOISTURE WILL WORK BACK INTO THE PICTURE ON 
WEDNESDAY...WITH A MORE NORTHEASTERLY WINDS.

EXTENDED OUTLOOK...SLIGHT CHANCE OF RAIN FRIDAY. RAIN MOVING IN THE 
LATTER PART OF SATURDAY...CONTINUING THROUGH SUNDAY WITH 
INTERMITTENT IFR CONDITIONS.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/... 
AS OF 300 PM TUESDAY...OFFSHORE/NWRLY POST-COLD FRONTAL WINDS 
THROUGH THE PERIOD WITH HIGH PRESSURE BUILDING IN FROM POINTS NORTH 
AND WEST. ADDITIONAL VEER TO MORE NRLY APPROX 06Z AS THE RIDGE AXIS 
GETS CLOSER...WHICH SHOULD ALSO ACT TO KNOCK A FEW KTS OFF THE WIND 
SPEEDS. SEAS FCST GENERALLY COMPRISED OF A WIND WAVE GIVEN THE 
ABSENCE OF SWELL ENERGY. THE FLOW BEING LARGELY OFFSHORE WILL OPEN 
UP A SMALL RANGE IN WAVE HEIGHT AS THE LANDMASS SHADOWS WAVE HEIGHTS 
SLIGHTLY WHILE SEAS STAY CLOSE TO 4 FT AWAY FROM THE WATER. 

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... 
AS OF 300 PM TUESDAY...THE MAIN FOCUS OF THE MID WEEK PERIOD WILL
BE THE ARRIVAL OF AN ARCTIC COLD FRONT WEDNESDAY NIGHT...AND A SUBSEQUENT
PERIOD OF MODERATE NORTHWEST BREEZES BEHIND THE FRONT EXTENDING
INTO THURSDAY EVENING. AT THIS TIME IT APPEARS WE MAY BE ABLE TO
GET THROUGH THE PERIOD WITHOUT SMALL CRAFT ADVISORIES...BUT MARINE
WEATHER CONDITIONS WILL NOT EXACTLY BE FAVORABLE. VERY COLD AIR
RELATIVE TO NORMALS FOR THE MONTH OF MARCH WILL CREATE WIND CHILLS
IN THE 30S EVEN OUT AT 10 AND 20 MILES FROM SHORE. 

LONG TERM /FRIDAY THROUGH SATURDAY/... 
AS OF 300 PM TUESDAY...HIGH PRESSURE RIDGING ACROSS THE WATERS 
FRIDAY CREATES LIGHT AND VARIABLE WINDS...ONLY DEVELOPING A 
PREDOMINANT NE DIRECTION LATE. THIS KEEPS WAVE HEIGHTS 
MINIMAL...REMAINING 1-2 FT THROUGH THE DAY. A COMPLEX FRONTAL SYSTEM 
AND COASTAL LOW THEN BEGIN TO IMPACT THE WATERS SAT/SUN WITH 
DETERIORATING MARINE CONDITIONS. NE WINDS WILL DEVELOP SATURDAY AND 
MAINTAIN THIS DIRECTION THROUGH THE EXTENDED WITH MINIMAL 
FLUCTUATIONS TO EAST OR NORTH AT TIMES...AT SPEEDS OF 10-15 KTS. 
SEAS BUILD GRADUALLY...FROM 1-2 FT EARLY SATURDAY...UP TO 4-6 FT 
SUNDAY AND A SMALL CRAFT ADVISORY MAY BE NEEDED MUCH OF SUNDAY.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...TRA
NEAR TERM...MBB
SHORT TERM...TRA
LONG TERM...JDW
AVIATION...MBB/HDL