000
FXUS62 KRAH 140726
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
325 AM EDT TUE MAY 14 2013

.SYNOPSIS...
HIGH PRESSURE WILL SHIFT TO THE EAST OF THE AREA TODAY.. RESULTING
IN A WARMING TREND.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 245 AM TUESDAY...

REST OF MORNING AND TODAY:
MID LEVEL CLOUD COVER ASSOCIATED WITH THE DEEP MID LEVEL TROUGH HAS
MOVED TO THE EAST OF THE AREA THIS MORNING... WITH ONLY PATCHES OF
HIGH CIRRUS MOVING ACROSS THE AREA FROM TIME TO TIME IN THE
NORTH-NORTHWEST UPPER LEVEL FLOW. THIS DEPARTURE OF THE THICKER MID
LEVEL CLOUD COVER AND WINDS BECOMING LIGHT AND VARIABLE TO CALM HAS
ALLOWED TEMPS TO FALL QUITE NICELY EARLY THIS MORNING. STILL THINK
THAT WE MAY SEE SOME PATCHY FROST ACROSS OUR NORTHERN COUNTIES IN
THE USUAL RURAL COLD SPOTS. THUS... WILL LEAVE THE FROST ADVISORY AS
UP AND AS IS. FOR RECORD LOW VALUES PLEASE SEE THE CLIMATE SECTION
BELOW.

SURFACE HIGH PRESSURE CURRENTLY OVER THE REGION THIS MORNING WILL
SHIFT TO THE EAST OF THE AREA BY THIS AFTERNOON... RESULTING IN A
WARMING TREND. ALOFT... HEIGHTS WILL INCREASE ACROSS CENTRAL NC
TODAY. HOWEVER... WE WILL STILL REMAIN IN NORTHWEST FLOW ALOFT...
WITH SOME MID AND HIGH LEVEL CLOUD COVER MOVING ACROSS THE AREA IN
THE NW FLOW FROM TIME TO TIME... POSSIBLY ENHANCED BY THE MOUNTAINS.
AFTERNOON LOW LEVEL THICKNESS VALUES ARE EXPECTED TO INCREASE SOME
12 TO 15 METERS OVER YESTERDAY AFTERNOONS VALUES. THIS SHOULD RESULT
IN A HIGH TEMPS IN THE LOWER TO MID 70S ACROSS THE AREA.

TONIGHT:
OUTSIDE OF A FEW WEAK DISTURBANCES ALOFT CONTINUING TO MOVE THROUGH
THE NW FLOW ALOFT... RESULTING IN PERIODS OF MID AND HIGH CLOUD
COVER FROM TIME TO TIME (MOST ACROSS THE NORTHEAST PIEDMONT AND
NORTHERN/CENTRAL COASTAL PLAIN)... EXPECT GENERALLY QUITE WEATHER
WITH DRY CONDITIONS. THANKS TO THE SOUTHERLY RETURN FLOW OVERNIGHT
TEMPS WILL BE QUITE A BIT WARMER FOR TONIGHT... WITH LOWS GENERALLY
IN THE LOWER TO MID 50S (WHICH IS STILL ABOUT A CATEGORY BELOW
NORMAL).

WEDNESDAY:
MID LEVEL RIDING IS EXPECTED TO BUILD ACROSS THE AREA ON WEDNESDAY
ALLOWING FOR SIGNIFICANT WARMING AND A GENERAL CONTINUATION OF QUITE
WEATHER. AFTERNOON LOW LEVEL THICKNESS VALUES ARE EXPECTED TO SOAR
INTO THE 1407 TO 1420 METER RANGE. THIS APPROXIMATE 50 METER
INCREASE FROM THIS AFTERNOON WILL YIELD MUCH WARMER TEMPS FOR
WEDNESDAY AFTERNOON. EXPECT HIGH TEMPS TO BE IN THE MID TO UPPER
80S... WITH EVEN A 90 DEGREE READING NOT OUT OF THE QUESTION. LOW
LEVEL MOISTURE IS PROGGED TO INCREASE AS WELL IN A STRENGTHENING
SOUTHWESTERLY LOW LEVEL FLOW. HOWEVER... THANKS TO THE WARMING MID
LEVELS AND ONLY MARGINAL LOW LEVEL MOISTURE... CONVECTIVE CHANCES
LOOK QUITE SMALL AT BEST. GIVEN THIS AND ONLY A LEE SIDE TROUGH
EXPECTED ON WEDNESDAY... THERE APPEARS TO BE A LACK OF ANY
APPRECIABLE FORCING TO SUPPORT MUCH IF ANY SHOWERS AND STORMS.
ALTHOUGH WE CANT COMPLETELY RULE OUT AND ISOLATED SHOWER/STORM OR
TWO PROBABILITIES WILL REMAIN TOO LOW TO INCLUDE IN THE FORECAST AT
THIS TIME.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
AS OF 325 AM TUESDAY...

WEAK BROAD RIDGING ALOFT...AHEAD OF A S/W ENTERING THE LOWER MS
VALLEY...WILL CROSS CENTRAL NC WEDNESDAY NIGHT. AT THE SURFACE...A
LEE SIDE TROUGH WILL EXIST ACROSS THE PIEDMONT. ASIDE FROM A FEW
PATCHES OF MID-HIGH LEVEL CLOUDS PASSING OVERHEAD...EXPECT FAIR
CONDITIONS. MIN TEMPS IN THE LOWER 60S.

THURSDAY...WARMTH CONTINUES WITH THICKNESSES IN THE AFTERNOON IN THE
1405-1410M RANGE. THIS IS SUPPORTIVE OF MAX TEMPS IN THE MID 80S
WITH A FEW UPPER 80S HIGHLY PROBABLE. THE S/W RIDGE ALOFT WEAKENS A
BIT...ALLOWING LEE SIDE TROUGH TO SHARPEN. THIS FEATURE ALONG WITH
AN INCREASINGLY MOIST AIR MASS MAY LEAD TO THE DEVELOPMENT OF
ISOLATED CONVECTION IN THE AFTERNOON...MAINLY IN THE
WESTERN-SOUTHERN PIEDMONT...AS MID LEVEL LAPSE RATES PROJECTED TO BE
NEAR 7 DEG C/KM.

THURSDAY NIGHT...UPPER HEIGHTS LOWER 20-40M AS LOWER MS VALLEY S/W
APPROACHES FROM THE WEST. INCREASING MOISTURE COUPLED WITH THE
PASSAGE OF A WEAK MID LEVEL TROUGH MAY BE ENOUGH TO CAUSE AN
ISOLATED SHOWER OR TWO ACROSS THE REGION OVERNIGHT. PATCHY CLOUD
COVERAGE AND A LIGHT SLY WIND WILL RESULT IN A MILD NIGHT WITH MIN
TEMPS LOW-MID 60S.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 325 AM TUESDAY...

FRIDAY...THE AFOREMENTIONED MID LEVEL S/W PROJECTED TO CROSS THE
CAROLINAS FRIDAY AFTERNOON. A MODEST COOL POOL ALOFT COUPLED WITH
AFTERNOON HEATING WILL RESULT IN A SLIGHT-MODERATELY UNSTABLE AIR
MASS BY AFTERNOON...SUPPORTIVE OF SCATTERED CONVECTION. BULK OF
CONVECTION WILL OCCUR IN ASSOCIATION WITH A WEAK SURFACE
BOUNDARY...DRIFTING SOUTHWARD FROM VIRGINIA. THUS...EXPECT SCATTERED
CONVECTION TO INITIATE NEAR THE VA BORDER COUNTIES BY MID-LATE
AFTERNOON...WITH CONVECTION DRIFTING SWD THROUGH THE EARLY
EVENING...FEEDING ON THE WARM MOIST AIR ACROSS THE
PIEDMONT-SANDHILLS. LOW LEVEL CONVERGENCE RATHER WEAK SO WILL LIMIT
RAIN CHANCES TO NO HIGHER THAN 30 PERCENT AT THIS TIME. IF LOW-MID
LEVEL CONVERGENCE INCREASES...COULD SEE A NEED FOR POPS OF 50-60
PERCENT BY LATE FRIDAY AFTERNOON ACROSS THE NORTHERN PIEDMONT.

SATURDAY...WEAK SURFACE BOUNDARY BEING HANDLED DIFFERENTLY BY MODEL
GUIDANCE WITH SOME (12Z ECMWF) TAKING THE BOUNDARY ALL THE WAY TO
THE SC BORDER BEFORE STALLING... WHILE OTHERS (00Z GEM, 00Z GFS)
STALL BOUNDARY IN VICINITY OF HIGHWAY 64. BULK OF MODEL GUIDANCE
ALSO DEPICT RISING HEIGHTS/WARMING ALOFT IN WAKE OF DEPARTING S/W.
FAVOR THE MORE NORTHERN POSITION AT THIS TIME DUE TO LACK OF
AGGRESSIVE PUSH FROM THE NORTH. THIS BOUNDARY WILL LIKELY SERVE AS A
FOCUS FOR MOISTURE POOLING/CONVERGENCE SATURDAY...LEADING TO
VARIABLY CLOUDY SKIES AND A THREAT FOR SCATTERED SHOWERS/ISOLATED
STORMS. SOUTH OF THE BOUNDARY...PARTIAL SUN SATURDAY MORNING-EARLY
AFTERNOON WILL DESTABILIZE THE ATMOSPHERE BUT LACK OF CONVERGENCE IN
THE LOW LEVELS AND MODEST MID LEVEL INVERSION MAY CAP THE ATMOSPHERE
ENOUGH TO KEEP CONVECTION ISOLATED. DEGREES OF CLOUDINESS WILL
DICTATE MAX TEMPS SATURDAY. SINCE ANTICIPATING MORE CLOUDS THAN SUN
ACROSS THE NORTH...HAVE LOWERED MAX TEMPS A COUPLE OF DEGREES NORTH
OF HIGHWAY 64 ( MAX TEMPS 80-82) WHILE HIGH TEMPS ACROSS THE SOUTH
SHOULD EASILY REACH THE MID 80S.

SUNDAY INTO THE MONDAY WILL SEE A PATTERN MORE TYPICAL OF EARLY
SUMMER WITH A RIDGE POSITIONED OFFSHORE AND A TROUGH PROGRESSING
EAST ACROSS THE CENTRAL U.S. THIS WILL RESULT IN A SLY FLOW ACROSS
OUR REGION. BEST MOISTURE TRANSPORT SUNDAY PROJECTED TO OCCUR
IMMEDIATELY WEST OF OUR REGION. WITH RESIDUAL AFFECTS OF THE RIDGE
OFFSHORE INFLUENCING OUR EASTERN AREAS...BELIEVE CONVECTION WILL BE
ISOLATED ACROSS THE EAST WHILE SCATTERED CONVECTION PROBABLE ACROSS
THE WEST WHERE MOISTURE AND LIFT WILL BE BETTER. ANOTHER WARM DAY
WITH MAX TEMPS IN THE LOW-MID 80S.

TROUGH TO OUR WEST GETS CLOSER MONDAY WHICH IS SUPPORTIVE OF
SLIGHTLY BETTER CHANCE FOR AFTERNOON CONVECTION...ESPECIALLY WEST OF
HIGHWAY 1. STILL CONTINUED WARM WITH AFTERNOON TEMPS 80-85.

MIN TEMPS THROUGH THE PERIOD MILD...IN THE LOW-MID 60S.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1AM TUESDAY...

24 HOUR TAF PERIOD:
VFR CONDITIONS ARE EXPECTED TO CONTINUE FOR THE 24 HOUR TAF PERIOD
AS SURFACE HIGH PRESSURE MOVES ACROSS THE REGION. HOWEVER... WE MAY
SEE PERIODS OF MID AN UPPER LEVEL CLOUD COVER IN THE NORTHWEST FLOW
ALOFT. DO NOT EXPECT AN PRECIP THOUGH. LIGHT AND VARIABLE WINDS THIS
MORNING WILL BECOME SOUTHERLY IN THE 5 TO 10 KT RANGE BY THIS
AFTERNOON AS THE SURFACE HIGH SLIPS TO THE EAST OF THE AREA.

OUTLOOK:
VFR CONDITIONS WILL CONTINUE THROUGH WEDNESDAY AS AN UPPER LEVEL
RIDGE BUILDS OVER THE EASTERN US. VFR CONDITIONS ARE EXPECTED TO
GENERALLY PREVAIL THROUGH THE END OF THE WEEK...WITH AN INCREASING
POTENTIAL FOR ISOLATED TO SCATTERED DIURNAL SHOWERS AND STORMS
LATE FRIDAY INTO THE WEEKEND... ALONG WITH THE POTENTIAL FOR SUB-
VFR VISBYS AND/OR CIGS IN THE PRE-DAWN HOUR LATE THIS WEEK INTO
THE WEEKEND.

&&

.CLIMATE...
RALEIGH... 43 DEGREES RECORDED MAY 14, 1997

GREENSBORO... 40 DEGREES RECORDED MAY 14, 1941

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY FROM 4 AM TO 8 AM EDT THIS MORNING FOR
NCZ007>011-021>024-026-038-039.

&&

$$
SYNOPSIS...BSD
NEAR TERM...BSD
SHORT TERM...WSS
LONG TERM...WSS
AVIATION...BSD/VINCENT
CLIMATE...BADGETT