FXUS61 KRNK 282016
AFDRNK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
316 PM EST SAT NOV 28 2009
.SYNOPSIS...
HIGH PRESSURE OVER THE GULF COAST REGION WILL MOVE EAST TONIGHT
AND SUNDAY. A COLD FRONT WILL MOVE THROUGH THE APPALACHIANS
MONDAY. WEDNESDAY AND THURSDAY A LARGE LOW PRESSURE SYSTEM WILL
MOVE FROM THE LOWER MISSISSIPPI VALLEY ACROSS THE MID ATLANTIC
STATES.
&&
.NEAR TERM /THROUGH SUNDAY/...
HIGH PRESSURE WILL BUILD EAST ACROSS OUR AREA TONIGHT. THE
MID-ATLANTIC REGION REMAINS IN A ZONE OF STRONG SYNOPTIC SUBSIDENCE
UPSTREAM OF THE OFFSHORE TROUGH AND DOWNSTREAM OF THE MIDWEST RIDGE.
DECOUPLING OF THE WINDS EXCEPT FOR THE RIDGES TONIGHT AND GOOD
RADIATIONAL COOLING WILL BE BALANCED BY WEAK WARM ADV AND INCREASES
IN DEW PTS. PLAYED LOW TEMPERATURES CLOSE TO THE COOLER ADJMAV.
HIGH PRESSURE WILL CONTINUE TO MOVE EAST OVER THE MID ATLANTIC REGION
SUNDAY. WITH WESTERLY FLOW RAISED HIGH TEMPERATURES A FEW DEGREES
NEAR ADJMET WITH READINGS GENERALLY FROM THE MID 50S TO THE MID 60S.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
HIGH PRESSURE PASSES TO THE SOUTH OF THE FORECAST AREA. THIS WILL
RESULT IN LOW LEVEL WINDS OUT OF THE SOUTHWEST THEN WEST. 850MB
TEMPERATURES REMAIN AROUND +8 THROUGH SUNDAY NIGHT. THERE WILL BE
ENOUGH MIXING AND CLOUD COVER SUNDAY NIGHT TO KEEP LOW TEMPERATURES
CLOSER TO MET GUIDANCE...MAINLY IN THE 40S.
OVERALL THE TIMING OF THE NEXT FRONT IN THE MODELS IS SLIGHTLY
SLOWER...WITH SOME DIFFERENCES REMAINING BETWEEN THE FASTER
GFS/ECMWF AND SLOWER NAM. ALL MODELS BRING THE FRONT THROUGH THE
FORECAST AREA ON MONDAY. EXPECT ANY MEASURABLE RAINFALL TO REACH THE
WESTERN COUNTIES AFTER 09Z MONDAY...THEN SPREAD EAST TO THE BLUE
RIDGE DURING THE MORNING.
PRECIPITABLE WATER VALUES CLIMB CLOSE TO AN INCH AHEAD OF THE FRONT
BUT WITH WESTERLY LOW LEVEL WINDS AHEAD OF THE BOUNDARY...CHANCE OF
PRECIPITATION EAST OF THE BLUE RIDGE WILL NOT BE AS GOOD AS IN THE
MOUNTAINS. INCREASED PROBABILITY OF RAIN IN THE WEST ON MONDAY
MORNING AND HELD AROUND 50 PERCENT IN THE EAST DURING THE AFTERNOON.
09Z SREFS FROM SPC AND NCEP BOTH HAD LESS THAN A 10 PERCENT CHANCE
OF 0.10 INCH OF RAINFALL EAST OF THE BLUE RIDGE ON MONDAY SO KEEP
QUANTITATIVE FORECAST PRECIPITATION VERY LIGHT.
HAVE COOLED DOWN THE LOWS ON MONDAY NIGHT BEHIND THE FRONT...BUT
FORECAST IS STILL ABOVE GUIDANCE IN THE EAST. LOW LEVEL JET BEHIND
THE FRONT MAY BE AS HIGH AS 40 KNOTS SO ALSO RAISED WIND
SPEEDS/GUSTS AT HIGHER ELEVATIONS ON MONDAY NIGHT. EXPECT UPSLOPE
CLOUDS AND PRECIPITATION MONDAY NIGHT BUT LIFT WILL DISSIPATE EARLY
ON TUESDAY.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AN UPPER LEVEL LOW WILL SPAWN A GULF DISTURBANCE ON WEDNESDAY. THE
UPPER LEVEL LOW WILL TRACK FROM TEXAS ON WEDNESDAY THEN INTO THE
OHIO VALLEY WEDNESDAY NIGHT. BY THURSDAY...THIS UPPER LEVEL FEATURE
WILL BE OCCLUDED OVER LAKE ERIE/SOUTHEASTERN CANADA. THE GULF
DISTURBANCE WILL STAY CLOSE TO THE UPPER LEVEL LOW AND TRACK INTO
THE TENNESSEE VALLEY...THROUGH THE OHIO VALLEY...AND INTO
SOUTHEASTERN CANADA. OVER THE MID ATLANTIC...A WEAKENING SURFACE
RIDGE WILL CONVERT INTO A COLD AIR WEDGE WEDNESDAY THROUGH THURSDAY
MORNING AS RAIN SPREADS ACROSS THE REGION. THIS WEDGE WILL ERODE
THURSDAY MORNING AS A COLD FRONT MOVES TO THE EAST COAST. A
SECONDARY LOW MAY FORM OVER THE CAROLINAS WEDNESDAY AFTERNOON AND
NIGHT TO HELP SPREAD RAIN ACROSS THE AREA AND ENHANCE THE WEDGE.
AN OVERRUNNING COLD RAIN WILL SLOWLY ADVANCE NORTH DURING THE DAY
WEDNESDAY. RAINFALL COULD BE HEAVY AT TIME WITH MOIST WARM AIR
ADVECTING OVER THE REGION AND AN INCREASING SOUTHEASTERLY LOW LEVEL
JET. RAINFALL AMOUNTS ON THE ORDER OF AN HALF OF AN INCH TO AN INCH
POSSIBLE WEDNESDAY INTO THURSDAY MORNING. HIGHER AMOUNTS OF AN INCH
OR TWO POSSIBLE ALONG EASTERN SLOPES OF THE BLUE RIDGE. RAINFALL
AMOUNTS COULD BE DRASTICALLY REDUCED IF SOUTHEAST COASTAL CONVECTION
IS MORE PRONOUNCED. EITHER WAY...WEDNESDAY INTO THURSDAY WILL BE
DAMP AND COLD. WITH AN EARLY ARRIVAL OF RAIN ...TEMPERATURES LIKELY
TO MAXIMIZE WEDNESDAY MORNING AND IN THE UPPER 40S TO LOWER 50S.
LITTLE DIURNAL SWING WEDNESDAY NIGHT AS THE WEDGE WITH WARM AIR
ALOFT KEEPING TEMPERATURES MILD NEAR 40F. DESPITE THE ABUNDANT
AMOUNT OF RAIN EXPECTED...THE WIND MAY BE THE BIGGER PROBLEM. MODELS
PROJECTING A SOUTHEASTERLY 60-70 KT LOW LEVEL JET WEDNESDAY NIGHT.
MAJORITY OF THE WINDS SHOULD NOT MIX DOWN WHILE THE WEDGE IS IN
PLACE. HOWEVER...THE WEDGE WILL BE WEAKER/SHALLOWER ACROSS THE
EXTREME WESTERN CWA. WIND ADVISORIES/WARNING POSSIBLE ACROSS THE
GRAYSON HIGHLANDS...RICHLANDS AND TAZEWELL AREA IF MODELS CONTINUE TO
SHOW THIS LOW LEVEL JET FORMING.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
VFR CONDITIONS EXPECTED UNDER NORTHERN NOSE OF HIGH PRESSURE THROUGH
THE NEXT 36 HRS. WINDS MAY STILL BE A LITTLE GUSTY THIS AFTERNOON
ACROSS THE HIGH TERRAIN. RIDGE TOP WINDS IN VCNTY OF TAF SITES MAY
STILL GUST TO 25 TO 30 KTS THROUGH FIRST HALF OF TODAY.
HIGH PRESSURE REMAINS ACROSS OUR AREA THROUGH SUNDAY. NEXT FRONTAL
SYSTEM WILL MOVE INTO THE WEST EARLY MONDAY BUT RAIN IS EXPECTED TO
BE LIGHT THROUGHOUT THE DAY MONDAY. MVFR CIGS/VSBYS CERTAINLY
POSSIBLE..ESPECIALLY AT LWB/BLF...BUT ANY IFR CONDITIONS SHOULD BE
VERY BRIEF. ALSO QUICK PERIOD OF SNOW SHWS AGAIN AT BLF AND LWB
BEHIND FRONT BY MONDAY NIGHT. ANOTHER GOOD CHANCE FOR RAIN BY
MIDWEEK...AND LOOKS LIKE A BETTER CHANCE FOR MORE WIDESPREAD IFR
CONDITIONS WITH THIS SYSTEM.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...AMS
NEAR TERM...KK
SHORT TERM...AMS
LONG TERM...RCS
AVIATION...KK/SK
