-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 121847
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
247 PM EDT SAT APR 12 2014

.SYNOPSIS...PERSISTENT HIGH PRESSURE IN THE WESTERN ATLANTIC WILL
MAINTAIN A DRY SURFACE RIDGE ACROSS THE CAROLINAS THROUGH SUNDAY. A
COLD FRONT ASSOCIATED WITH A DEVELOPING LOW PRESSURE SYSTEM WILL
SLOWLY APPROACH THE REGION FROM THE WEST ON MONDAY...THEN MOVE EAST
ACROSS NORTH CAROLINA AND VIRGINIA MONDAY NIGHT AND TUESDAY.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
AS OF 230 PM SATURDAY...

WITH SHORTWAVE RIDGING OVERHEAD AND OFFSHORE SURFACE HIGH PRESSURE
STILL EXTENDING INTO THE REGION...EXPECTING CONTINUED QUIET WEATHER
FOR CENTRAL NC. SOUTHERLY FLOW WILL DEVELOP AREAWIDE AS A BOUNDARY
THAT WAS DRAPED ACROSS THE AREA THIS MORNING WASHES OUT. THIS WILL
CAUSE LOW LEVEL MOISTURE TO BEGIN TO SLOWLY INCREASE THROUGH THE
OVERNIGHT HOURS. AS A RESULT...OVERNIGHT LOWS WILL LIKELY BE A
COUPLE OF DEGREES WARMER...GENERALLY IN THE MID TO UPPER 50S. BOTH
THE UPPER LEVEL AND SURFACE RIDGING WILL PUSH FURTHER OFFSHORE ON
SUNDAY AHEAD OF AN APPROACHING DEEP TROUGH/STRONG COLD FRONT.
STRENGTHENING SOUTHWESTERLY FLOW WILL BEGIN TO ADVECT MOISTURE EVEN
MORE SO INTO CENTRAL NC. DESPITE THIS INCREASING MOISTURE...IN THE
ABSENCE OF ANY SIGNIFICANT FORCING AND A FAIRLY CAPPED AIR MASS (PER
FORECAST SOUNDINGS)...SUNDAY IS EXPECTED TO REMAIN DRY. MAX LOW
LEVEL THICKNESS VALUES ARE PROGGED TO BE SIMILAR THOSE SEEN ON
SATURDAY AND THEREFORE...HIGHS SHOULD ONCE AGAIN BE IN THE UPPER 70S
TO LOWER 80S. CLOUDS WILL BE ON THE INCREASE... ESPECIALLY LATE
SUNDAY INTO EARLY MONDAY. THEREFORE OVERNIGHT LOWS WILL BE EVEN
WARMER...WITH TEMPS ONLY EXPECTED TO FALL INTO THE UPPER 50S TO
AROUND 60 DEGREES.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
-- Changed Discussion --
AS OF 244 PM SATURDAY...

DEEP TROUGH OVER THE CENTRAL US WILL PUSH EASTWARD. AN INITIAL
SHORTWAVE WILL EJECT NORTHEASTWARD... WITH SECOND TRAILING SHORTWAVE
DIGGING INTO THE SOUTHERN PLAINS. MOISTURE WILL BEGIN TO INCREASE
AHEAD OF THIS SYSTEM ACROSS THE AREA... AND MODEL TRAJECTORIES SHOW
GULF MOISTURE BEGINNING TO STREAM IN TO THE AREA MONDAY AFTERNOON...
AND SHALLOW ISENTROPIC LIFT MAY INDUCE SOME SHOWER ACTIVITY... WITH
THE POSSIBILITY OF A THUNDERSTORM. CONTINUED MILD HIGHS IN THE MID
TO UPPER 70S.

TIMING OF THE FRONTAL PASSAGE LOOKS TO BE BETWEEN 18Z TUES AND 06Z
WED... DIFFICULT TO PINPOIN BASED ON THE POTENTIAL WAVY NATURE OF
THE FRONT. INSTABILITY LOOKS LIKELY TO REMAIN LIMITED... WITH CLOUD
COVER ACROSS THE AREA... ALTHOUGH BASED ON THE LATER DAY TIMING SOME
WEAKER INSTABILITY IS POSSIBLE... AND IN CONCERT WITH MARGINAL
SHEAR... A 120 KT JET SITUATED ALONG THE APPALACHIANS... AND
FRONTOGENETICAL FORCING... MAY SUPPORT A FEW STRONGER STORMS. HEAVY
RAIN IS ALSO A THREAT... WITH PWS CLIMBING ABOVE 1.5 INCHES... 2 STD
DEV ABOVE CLIMATOLOGY. COOLER HIGHS IN THE UPPER 60S TO LOW 70S.
-- End Changed Discussion --

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
-- Changed Discussion --
AS OF 245 PM SATURDAY...

ECMWF REMAINS SLOWER AND SHARPER WITH THE PROGRESSION OF THE
SHORTWAVE ACROSS THE AREA... AND THE POTENTIAL EXISTS FOR SECONDARY
SURFACE WAVE DEVELOPMENT... WHICH COULD RESULT IN LINGERING
PRECIPITATION CHANCES INTO WEDNESDAY. AS THE SYSTEM DEPARTS... A
1035 MB HIGH BUILDS IN TO THE NORTHEAST AND WEDGES DOWN THE EAST
COAST... BRINGING NORTHEASTERLY FLOW TO THE AREA. COLDEST NIGHT
LOOKS TO BE WEDNESDAY NIGHT ... WITH FROST/FREEZE CONCERNS LOOKING
INCREASINGLY LIKELY ACROSS MUCH OF THE AREA. THE WEDGE MAY STAY IN
PLACE THROUGH THE REMAINDER OF THE PERIOD... AS THE DETAILS OF THE
EROSION MECHANISM IN THE FORM OF A NORTHERN STREAM ARE QUITE
UNCERTAIN AT THIS TIME PERIOD. WEDGE REGIME WILL RESULT IN BELOW
NORMAL TEMPERATURES... POTENTIALLY LASTING INTO SATURDAY.
-- End Changed Discussion --

&&

.AVIATION /18Z SATURDAY THROUGH FRIDAY/...
AS OF 130 PM SATURDAY...

VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE CURRENT TAF
PERIOD. WINDS WILL BE GENERALLY LIGHT AND VARIABLE ACROSS THE
NORTHERN HALF OF THE FORECAST AREA AS A WEAK BOUNDARY REMAINS DRAPED
ACROSS THE CENTRAL NC...WITH LIGHT SOUTHWESTERLY WINDS ELSEWHERE.
HOWEVER...AS THE BOUNDARY WASHES OUT...WINDS SHOULD BECOME MORE
SOUTHERLY AT ALL TAF SITES THROUGH THE AFTERNOON/EVENING HOURS. THEN
AFTER LIGHT AND VARIABLE WINDS OVERNIGHT...SOUTHERLY WINDS WITH
GUSTS UP TO 15-20 MPH WILL DOMINATE ON SUNDAY. JUST SOME SCATTERED
FLAT DIURNAL CU WITH BASES BETWEEN 4-6 KFT WILL BE POSSIBLE TODAY
AND THEN EVEN MORE SO ON SUNDAY.

OUTLOOK...VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE
REMAINDER OF THE WEEKEND. LOW STRATUS/FOG MAY DEVELOP LATE SUNDAY
NIGHT/EARLY MONDAY MORNING AS LOW LEVEL MOISTURE REALLY BEGINS TO
INCREASE. THEN A PERIOD OF WIDESPREAD ADVERSE AVIATION CONDITIONS IS
EXPECTED LATE MONDAY THROUGH TUESDAY AS A STRONG COLD FRONT
APPROACHES FROM THE WEST. CONDITIONS WILL THEN IMPROVE AGAIN BY
MIDWEEK.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...VINCENT
NEAR TERM...KRD
SHORT TERM...SEC
LONG TERM...SEC
AVIATION...KRD