000
FXUS62 KRAH 121951
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
251 PM EST FRI MAR 12 2010
.SYNOPSIS...
UNSETTLED WEATHER WITH OCCASIONAL SHOWERS IS EXPECTED THROUGH SUNDAY
IN ASSOCIATION WITH SEVERAL UPPER LEVEL DISTURBANCES.
&&
.NEAR TERM /THROUGH SATURDAY/...
AS OF 120 PM FRIDAY...
LITTLE CHANGE FROM EARLIER THINKING. STILL EXPECT BULK OF PRECIP TO
OCCUR TONIGHT...SHIFTING NEWD SATURDAY MORNING.
AT 18Z...999MB SURFACE LOW POSITIONED SE OF CAPE FEAR. THIS SLOWLY
DEEPENING SYSTEM HAS ENHANCED LOW LEVEL ELY ACROSS THE CENTRAL AND
NORTHERN COASTAL PLAIN...ADVECTING ATLANTIC MOISTURE INTO THE
REGION. AS AFTERNOON WEARS ON...EXPECT SHOWERS TO BECOME NUMEROUS
OVER THE NORTHERN HALF OF THE FORECAST AREA.
LATE THIS AFTERNOON THROUGH THIS EVENING EXPECT RAINFALL INTENSITY
TO PICK-UP IN THE FAR W-NW AS UPPER DIVERGENCE WILL BE INCREASING AS
A RESULT OF STRONG 300MB JET CROSSING THE NORTHERN GULF INTO THE
CENTRAL FL PENINSULA. FAIRLY DEEP (BELOW 8000FT) E-SE FLOW AS A
RESULT OF SURFACE LOW IN VICINITY OF THE SOUTHERN-CENTRAL NC COAST
AND A DISTINCT 850MB TROUGH APPROACHING FROM THE SW WILL CREATE
DECENT UPSLOPE FLOW PARAMETERS. THIS SHOULD RESULT IN PERIODS OF
MODERATE TO LOCALLY HEAVY RAINFALL IMMEDIATELY WEST-NORTH OF CENTRAL
NC. THE GREATEST THREAT FOR ANY PROLONG MODERATE RAIN IN OUR REGION
WILL BE OVER THE TRIAD THEN NE ALONG THE VA BORDER COUNTIES.
PROJECTED RAINFALL AMOUNTS BETWEEN A HALF TO ONE INCH ARE WELL BELOW
FLASH FLOOD GUIDANCE SO DO NOT ANTICIPATE A WATCH. HOWEVER COULD
HEAR RUMBLES OF THUNDER LATE THIS EVENING AND OVERNIGHT AS 850-500MB
LAPSE RATES INCREASE TO BETWEEN 6-6.5 DEG C/KM. WIND PROFILE WHILE
SUPPORT OF SOME UPDRAFTS THE MAGNITUDE OF THE WINDS ARE WEAK TO
MARGINAL SO NOT EXPECTING ANY SEVERE STORMS.
ON SATURDAY...850MB TROUGH LIFTS NE AWAY FROM THE REGION. IN ITS
WAKE...WLY FLOW WILL ADVECT DRIER AIR INTO THE REGION. APPROACH OF
MUD/UPPER LEVEL CYCLONE THOUGH WILL RESULT IN 850-500MB LAPSE RATES
APPROACHING 7 DEG C/KM. ANY RESIDUAL MOISTURE COUPLED WITH THIS
INSTABILITY ALOFT WOULD SUPPORT ISOLATED THUNDERSTORMS...ESPECIALLY
EAST OF HIGHWAY 1. WIND PROFILE UNIDIRECTIONAL BUT ONLY 25-30KTS
THROUGH THE COLUMN. THUS COULD SEE SOME WIND GUSTS 30-35KTS WITH THE
STORMS. MAY SEE SOME HAIL THOUGH WITH ANY STORMS WITH SUSTAINED
UPDRAFTS DUE TO FREEZING LEVELS BETWEEN 6000-8000FT.
TEMPS SATURDAY DEPENDENT UPON WHETHER ANY BREAKS OCCUR. DUE TO THE
DOWNSLOPE COMPONENT OF THE LOW LEVEL AND SUBSIDENCE BEHIND THE
EXITING MID LEVEL TROUGH...MAY SEE ENOUGH BREAKS TO ALLOW FOR FOR
SOME PARTIAL SUN. DUE TO RELATIVE MILD CONDITIONS OVERNIGHT...COULD
SEE TEMPS REBOUND 15-18 DEGREES FROM MORNING LOW TEMPS. THUS HAVE
RAISED MAX TEMPS ABOUT 3 DEGREES FROM PREVIOUS FORECAST.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 245 PM FRIDAY...
SATURDAY NIGHT:
COLD ADVECTION IN THE LOW LEVELS ON SATURDAY EVENING
WILL HELP TO INCREASE STABILITY IN THE LOW LEVELS OF THE
ATMOSPHERE... AS THE SURFACE TROUGH/COLD FRONT MOVES THROUGH THE
AREA. HOWEVER... THE POTENT MID/UPPER LOW IS EXPECTED TO MOVE ACROSS
THE AREA ON SATURDAY NIGHT/SUNDAY EVENING. THUS... EVEN WITH THE
DECREASING INSTABILITY IN THE LOW LEVEL EXPECT WE COULD STILL SEE
SOME SHOWERS CONTINUE/DEVELOP INTO THE OVERNIGHT HOURS... WITH THE
NAM MORE EXCITED ABOUT CHANCES FOR SHOWERS AND THE GFS. FOR NOW WILL
GO WITH A CHANCE OF SHOWERS CWA WIDE. WITH MOSTLY CLOUDY SKIES
EXPECTED... TEMPS SHOULD BOTTOM OUT IN THE LOWER TO MID 40S.
SUNDAY THROUGH MONDAY NIGHT:
MID/UPPER LEVEL LOW BEGINS TO LIFT OFF TO THE NORTHEAST DURNING THIS
PERIOD. HOWEVER... S/W ENERGY AND MOISTURE WRAPPING AROUND THE LOW
WILL KEEP AT LEAST ISOLATED CHANCES FOR SHOWERS ACROSS THE AREA
DURING THE DAY ON SUNDAY. OTHERWISE... SKIES ARE EXPECTED TO REMAIN
PARTY TO MOSTLY CLOUDY THROUGH THE PERIOD. HIGH TEMPS SUNDAY AND
MONDAY LOOK TO GENERALLY RANGE FROM THE UPPER 50S TO LOWER 60S...
WITH OVERNIGHT LOWS IN THE UPPER 30S TO LOWER 40S.
&&
.LONG TERM /TUESDAY THROUGH THURSDAY/..
AS OF 125 PM FRIDAY:
BROAD CYCLONIC FLOW ALOFT IS EXPECTED TO CONTINUE ACROSS THE REGION
THROUGH A GOOD PORTION OF THE EXTENDED... WITH SURFACE HIGH PRESSURE
DRIFTING/BUILDING INTO THE AREA FROM THE NORTHWEST. ANOTHER S/W IS
EXPECTED TO TRACK THROUGH THE L/W PATTERN DURING NEXT WEEK... AND
CLOSE OFF OVER THE GULF COAST STATES ON WEDNESDAY NIGHT INTO
THURSDAY. AS THE MID/UPPER LEVEL LOW MOVES SLOWLY EASTWARD ACROSS
THE GULF STATES A SURFACE LOW IS EXPECTED TO DEVELOP OF THE
SOUTHEASTERN U.S. COAST ON THURSDAY. HOWEVER... THE BEST LIFT AND
MOISTURE ASSOCIATED WITH THIS SYSTEM ARE EXPECTED TO REMAIN TO THE
SOUTH AND EAST OF THE AREA. THUS... WILL CONTINUE A DRY FORECAST
DURING THIS TIME. TEMPS LOOK TO BE NEAR TO SLIGHT BELOW NORMAL
DURING THIS TIME FRAME... AS LOW LEVEL FLOW REMAINS NORTH TO
NORTHEASTERLY. EXPECT HIGH TEMPS IN THE UPPER 50S TO LOWER 60S...
THROUGH THURSDAY. LOWS DURING THE EXTENDED LOOK TO REMAIN NEAR
NORMAL... UPPER 30S TO LOWER 40S.
EXPECT DRY CONDITIONS TO CONTINUE INTO FRIDAY... HOWEVER...
QUESTIONS REMAIN WITH REGARD TO HOW AMPLIFIED THE UPPER LEVEL FLOW
PATTERN WILL BE ACROSS THE NORTH AMERICA LATE NEXT WEEK. THE GFS
CONTINUES TO BE QUITE PROGRESSIVE... ALLOWING LOW LEVEL FLOW TO
BECOME SOUTHERLY ON FRIDAY... WHILE THE EC CONSIDERABLE SLOWER.
HOWEVER... LOW LEVEL THICKNESS VALUES DO INCREASE ON THE EC AS BROAD
TROUGHINESS BEGINS TO MOVE EAST OF THE AREA... GIVING WAY TO
INCREASING HEIGHTS. HPC STILL PREFERS THE EC LATE NEXT WEEK...
DESPITE THE FEELING THAT IT MAY BE A BIT TOO SLOW AND AMPLIFIED.
THUS... WILL THE UNCERTAINTY WILL TREND HIGH TOWARDS CLIMO... WITH
HIGHS IN THE LOWER TO MID 60S.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 100 PM FRIDAY...
A PROLONG PERIOD OF IFR/MVFR CEILINGS EXPECTED THROUGH SATURDAY
MORNING AS MOIST LOW LEVEL E-SE FLOW COUPLED WITH THE APPROACH OF AN
UPPER LEVEL DISTURBANCE FROM THE WEST-SW WILL CAUSE EXTENSIVE
CLOUDINESS ALONG WITH SCATTERED TO NUMEROUS SHOWERS...ESPECIALLY
ACROSS THE WESTERN AND NORTHERN PIEDMONT INTO THE NORTHERN COASTAL
PLAIN. THE APPROACH OF THE UPPER LEVEL SYSTEM LATE TONIGHT WILL
INCREASE THE MID LEVEL LAPSE RATES...SLIGHTLY ENHANCING THE
POTENTIAL FOR ISOLATED THUNDER. THIS THREAT APPEARS TO BE GREATEST
BETWEEN CHARLOTTE AND FAYETTEVILLE.
THE THREAT FOR ISOLATED THUNDER WILL CONTINUE SATURDAY INTO EARLY
SATURDAY EVENING AS ANOTHER UPPER LEVEL SYSTEM APPROACHES FROM THE
WEST. NOT TOO OVERLY CONCERN WITH STRONG WIND GUSTS BUT THE STRONGER
STORMS MAY BE ACCOMPANIED BY SMALL HAIL. OTHERWISE EXPECT MVFR OR
LOW END VFR CEILINGS SATURDAY THROUGH EARLY SUNDAY.
MAY SEE ISOLATED TO SCATTERED SHOWERS SUNDAY AFTERNOON AS UPPER
LEVEL LOW WILL RESIDE ALOFT. THIS SYSTEM DRIFTS EAST SUNDAY NIGHT.
IN ITS WAKE...LOW AND MID LEVEL FLOW WILL BACK NLY...ADVECTING DRIER
MORE STABLE AIR INTO THE REGION. THIS WILL LEAD TO A PERIOD OF VFR
CONDITIONS MONDAY THROUGH WEDNESDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...WSS/VINCENT
NEAR TERM...WSS
SHORT TERM...BSD
LONG TERM...BSD
AVIATION...WSS
