FXUS62 KRAH 281850
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
150 PM EST SAT NOV 28 2009
.SYNOPSIS...
HIGH PRESSURE WILL BUILD TOWARD THE CAROLINAS FROM THE SOUTHWEST
TODAY AND MOVE OFFSHORE ON SUNDAY. A COLD FRONT WILL APPROACH THE
CAROLINAS FROM THE WEST SUNDAY NIGHT...MOVING THROUGH THE AREA
MONDAY AFTERNOON AND EVENING.
&&
.NEAR TERM /THROUGH SUNDAY NIGHT/...
AS OF 130 PM SATURDAY...
TONIGHT:
THE SOUTHERN STREAM WAVE CURRENTLY OVER EASTERN TX/LA IS PROGGED TO
MOVE EAST THROUGH THE DEEP SOUTH INTO THE SOUTHEAST STATES BY 12Z
SUN. AN INCREASE IN UPPER LEVEL CLOUD COVER ACROSS CENTRAL NC IS
LIKELY BETWEEN 09Z TO 12Z SUN. HOWEVER..DUE TO THE LATE ARRIVAL OF
THE MID AND HIGH CLOUDS...STRONG RADIATIONAL COOLING THROUGH THE
FIRST HALF OF THE NIGHT SHOULD STILL ALLOW TEMPERATURES TO DROP
SHARPLY AFTER SUNSET. THUS WILL LEAVE MIN TEMPS PRETTY MUCH
UNCHANGED AND ON THE COOL SIDE OF MOS STATISTICAL GUIDANCE. LOWS IN
THE MID 30S IN MOST LOCATIONS...ALTHOUGH LOWER 30S WILL BE POSSIBLE
IN THE TYPICAL COLD AREAS.
SUNDAY AND SUNDAY NIGHT:
MID AND HIGH LEVEL CLOUD COVER ASSOCIATED WITH THE SOUTHERN STREAM
WAVE PASSING JUST SOUTH OF THE AREA WILL RESULT IN PARTLY SUNNY TO
PARTLY CLOUDY SKIES THROUGH THE LATE MORNING HOURS. THEN EXPECT TO
SEE A SMALL 3 TO 6 HOUR WINDOW OF MOSTLY SUNNY/CLEAR SKIES BEFORE
THE NEXT BATCH OF MID AND HIGH LEVEL CLOUD COVER SPREADS INTO THE
STATE FROM THE WEST...DOWNSTREAM OF THE STRENGTHENING FRONTAL ZONE
AND WESTERLY 140KT UPPER LEVEL JET EXTENDING ACROSS THE
MID-MISSISSIPPI AND TN VALLEY. EXPECT PARTLY CLOUDY SKIES BY
SUNSET...WITH CEILINGS AT OR ABOVE 15 KFT. HIGH TEMPS WILL BE
COMPLICATED BY THE AMOUNT AND OPACITY OF UPPER LEVEL CLOUD COVER
OVER THE AREA. THICKNESSES ARE PROGGED TO INCREASE TO AROUND
1360-1365M SUN...AND WITH FULL SUN...LOCAL RESEARCH WOULD SUGGEST
HIGHS IN THE UPPER 60S. A MAV/MET MOS GUIDANCE BLEND YIELDS
SIMILAR VALUES...WARMEST IN THE SOUTH. UNDER THE THICKENING CLOUD
COVER AND A STEADY 5KT SOUTHWEST RETURN FLOW...LOWS SUNDAY NIGHT
WILL BE A GOOD TEN DEGREES WARMER THAN THE PREVIOUS NIGHT...LOWS
IN THE MID 40S.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 145 PM...
MONDAY AND MONDAY NIGHT
MODELS IN AGREEMENT IN PLACING AN 850 MILLIBAR TROUGH FROM
MEMPHIS NORTHEAST INTO THE MID ATLANTIC STATES AT SUNRISE MONDAY.
THIS WILL BE THE DRIVING FORCE FOR PRECIPITATION... WITH A
RELATIVELY WEAK 35 TO 40 KNOT 850 MILLIBAR JET MOVING THROUGH
NORTH CAROLINA AHEAD OF THE TROUGH. FLOW IS RELATIVELY UNIFORM
WITH NO SIGNIFICANT ISENTROPIC LIFT... AND THIS WILL LIMIT
RAINFALL AMOUNTS. INDICATIONS ARE HEAVIEST RAINFALL WILL BE NEAR
AND EAST OF HIGHWAY ONE...PERHAPS TO ONE QUARTER INCH... AS THE
LOW LEVEL JET SLIGHTLY ENHANCES LIFT DURING THE AFTERNOON.
THICKENING CLOUDS AND PRECIPITATION WILL HINDER AFTERNOON HEATING.
WITH THE CURRENT TIMING OF RAIN... AND EARLY AFTERNOON THICKNESSES
EXPECTED TO EXCEED 1350 METERS... HIGH TEMPERATURES NEAR 60
NORTHWEST TO UPPER 60S SOUTHEAST.
THE GFS MODEL HAS BEEN MOST AGGRESSIVE WITH LIFTING THE TROUGH OUT
INTO THE ATLANTIC AND THE 12Z RUN CONTINUES TO BE AN OUTLIER. WILL
CONTINUE RAIN CHANCES IN THE EAST INTO THE EARLY MORNING HOURS OF
TUESDAY. MODELS USUALLY TOO AGGRESSIVE WITH BRINGING COLD AIR OVER
THE MOUNTAINS... AND LOCATIONS IN THE NORTH COULD HAVE AT LEAST A
LITTLE MOISTURE ON THE GROUND TO HOLD TEMPERATURES UP. LOW
TEMPERATURES IN THE MID TO UPPER 30S NORTH... WITH 40 TO 45
DEGREES IN THE SOUTH.
TUESDAY AND TUESDAY NIGHT
THE EXITING LOW LEVEL TROUGH IS QUICKLY REPLACED BY SURFACE HIGH
PRESSURE... WHICH QUICKLY CROSSES THE CAROLINAS TUESDAY AND IS
OFFSHORE TUESDAY NIGHT. SOME CIRRUS EXPECTED TO TOP THE UPPER
LEVEL RIDGE OVER THE SOUTHEAST BUT OVERALL IT SHOULD BE SUNNY
TUESDAY. LOW LEVEL THICKNESSES EXPECTED TO BE NEAR CLIMATOLOGY AND
HIGH TEMPERATURES WILL FOLLOW SUIT... AT 54 TO 59 DEGREES.
SIMILARLY... LOW TEMPERATURES SHOULD NOT BE FAR FROM CLIMATOLOGY...
AT MID 30S.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 145 PM...
WEDNESDAY MORNING AN UPPER LEVEL CUT OFF LOW IS FORECAST TO BE OVER
EASTERN TEXAS. AN ASSOCIATED SURFACE LOW IN THE NORTH GULF OF MEXICO
WILL LIFT NORTHEAST TOWARD THE CAROLINAS DURING THE DAY WEDNESDAY.
AT THIS TIME THE ATTEMPT OF THE GFS TO DEVELOP A MILLER B SURFACE
LOW DEVELOPMENT... BUT OVER THE EASTERN PIEDMONT IS REJECTED... AND
SOMETHING CLOSER TO THE ECMWF SOLUTION WITH A LOW WEST OF THE
MOUNTAINS WILL BE FOLLOWED. WITH CENTRAL NORTH CAROLINA IN THE WARM
SECTOR... THIS COULD BE A SIGNIFICANT RAIN EVENT... WITH AMOUNTS IN
EXCESS OF ONE INCH. HOWEVER THERE IS STILL TOO MUCH UNCERTAINTY THIS
FAR OUT IN TIME TO HAVE MUCH CONFIDENCE.
THE REMAINDER OF THE PERIOD WILL BE DOMINATED BY A BROAD TROUGH OVER
THE EASTERN HALF OF THE UNITED STATES. SURFACE HIGH PRESSURE TO THE
WEST WILL KEEP SKIES MOSTLY CLEAR WHILE NORTHEAST FLOW AND DRY
NIGHTS WILL KEEP TEMPERATURES BELOW NORMAL. AFTERNOON HIGH
TEMPERATURES IN THE MID 50S BEFORE FALLING TO 49 TO 55 FRIDAY... AND
NEAR 50 SATURDAY. OVERNIGHT LOWS MID 40S TO NEAR 50 WEDNESDAY NIGHT
THEN MID 30S THURSDAY AND FRIDAY NIGHTS.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
AS OF 1230 PM SATURDAY...
VFR CONDITIONS THROUGH THE 24 HOUR TAF PERIOD AS HIGH PRESSURE
BUILDS TOWARD THE CAROLINAS FROM THE SOUTHWEST. WESTERLY SURFACE
WINDS WILL VEER TO LIGHT SOUTHWEST WINDS LATE THIS
AFTERNOON...BECOMING CALM OVERNIGHT. CIRRUS WILL OVERSPREAD THE
AREA JUST BEFORE SUNRISE SUNDAY MORNING AS UPPER LEVEL DISTURBANCE
OVER THE DEEP SOUTH PASSES JUST SOUTH OF THE REGION.
LOOKING BEYOND SUNDAY...TOP-DOWN MOISTENING WILL BEGIN IN EARNEST
ON MONDAY IN ADVANCE OF A COLD FRONTAL PASSAGE MONDAY EVENING.
A 6-12 HOUR PERIOD OF MVFR/IFR CONDITIONS ASSOC/W SHOWER ACTIVITY IS
LIKELY...WITH THE BEST CHANCE OF ADVERSE AVIATION CONDITIONS BETWEEN
18Z MON AND 06Z TUE. VFR CONDITIONS WILL RETURN ON TUESDAY AS
HIGH PRESSURE BUILDS IN BRIEFLY BEHIND THE FRONT. A STRONG
STORM SYSTEM IS EXPECTED TO DEVELOP ALONG THE DEEP SOUTH GULF COAST
TUE NIGHT...MOVING INTO THE CAROLINAS ON WEDNESDAY. WIDESPREAD IFR
TO LIFR AVIATION CONDITIONS ARE LIKELY WEDNESDAY AFTERNOON THROUGH
THURSDAY MORNING AS LOW PRESSURE SYSTEM MOVES ACROSS THE CAROLINAS.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
NEAR TERM...BL
AVIATION...BL
