AREA FORECAST DISCUSSION
NWS COLUMBIA SC
651 AM EST WED JAN 28 2009
.SYNOPSIS...
LOW PRESSURE WILL QUICKLY MOVE NORTHWEST OF THE CAROLINAS THIS
MORNING WITH A COLD FRONT CROSSING THE AREA THIS AFTERNOON AND
EVENING. THE COLD FRONT WILL PUSH OFFSHORE TONIGHT WITH HIGH
PRESSURE SLOWLY BUILDING IN THURSDAY AFTERNOON AND MAINTAINING
CONTROL OF THE REGION THROUGH THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LOW PRESSURE WILL CONTINUE THE MARCH UP THE WEST SIDE OF THE
APPALACHIANS TODAY AND INTO THE CANADIAN MARITIMES TONIGHT. AS THE
LOW MOVES THROUGH THE REGION THIS MORNING INCREASING SOUTHERLY
WINDS WILL FINALLY FORCE THE WEDGE TO RETREAT. HOWEVER THIS WILL
NOT ALLEVIATE THE CLOUDS AND CHANCES OF PRECIPITATION....AS THE
ASSOCIATED COLD FRONT WILL RAPIDLY BE KNOCKING ON THE DOORSTEP AND
BRINGING ANOTHER CLOUD FILLED DAY WITH INCREASING CHANCES OF
PRECIPITATION. WITH THE INCREASED PRESSURE GRADIENT OVER THE
REGION TODAY...MAINLY AHEAD OF THE FRONT...WINDS WILL QUICKLY
INCREASE AND BECOME GUSTY THIS MORNING BEFORE SUBSIDING BY
MIDNIGHT. THE SILVER LINING TO THE WINDS WILL BE THE WARM AIR
ADVECTION...WITH MOST LOCATIONS EXPECTED TO REACH THE UPPER 60S
AND LOWER 70S. BY MID AFTERNOON THE COLD FRONT WILL BE MOVING INTO
THE WESTERN MIDLANDS AND CSRA WITH CHANCE OF SHOWERS QUICKLY
INCREASING. DURING THE AFTERNOON HOURS EXPECT MOST LOCATIONS TO
SEE SOME RAINFALL WITH THE HIGHEST AMOUNTS ACROSS THE WESTERN
MIDLANDS AND CSRA. BY MID EVENING THE FRONT WILL BE OVER THE
EASTERN MIDLANDS AND REACH THE COAST AROUND MIDNIGHT. AS SUCH
EXPECT THE BEST CHANCE OF RAIN TO BE OVER THE CENTRAL AND EASTERN
MIDLANDS WHERE ONE TO TWO TENTHS OF RAIN WILL BE POSSIBLE. DURING
THE EARLY MORNING HOURS THE FRONT WILL MOVE OFFSHORE WITH THE
SHOWERS ENDING AND CLOUDS DISSIPATING AS DRIER AIR FILTERS INTO
THE REGION ON LIGHT NORTHWEST WINDS.
WITH THE PRESSURE GRADIENT TIGHTENING AHEAD OF THE FRONT AND WINDS
EXPECTED AROUND 15 MPH AND HIGHER GUSTS...20 KNOTS WITH GUSTS AROUND
30 ON AREA LAKES...WILL CONTINUE WITH THE LAKE WIND ADVISORY 10AM
TO 8PM.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
COLD FRONT STALLS OFFSHORE WITH COOLER AND DRIER AIR BECOMING
DOMINANT OVER THE REGION FOR THE SHORT TERM. WITH THE FRONT
STALLED JUST OFFSHORE THURSDAY AND THURSDAY NIGHT WILL SEE A BIT
MORE CLOUDS OVER THE EASTERN MIDLANDS AND CSRA WITH ANY
PRECIPITATION CONFINED TO THE COAST AND OFFSHORE. COUPLE OF OTHER
POINTS HERE FOCUS ON A BIT OF CLOUD COVER AS THE UPPER LEVEL
TROUGH SWINGS THROUGH ON FRIDAY INTO FRIDAY NIGHT AND WINDS ON
FRIDAY. WITH HIGH PRESSURE BUILDING IN COLD AIR ADVECTION WILL
BECOME PROMINENT ON FRIDAY AS THE PRESSURE GRADIENT ONCE AGAIN
TIGHTENS OVER THE REGION. THIS COMBINATION WILL PUSH WINDS TO
AROUND 15 MPH WITH GUSTS AROUND 25 MPH THROUGH THE DAY...WITH
SLIGHTLY HIGHER WINDS ON AREA LAKES PERSISTING INTO FRIDAY NIGHT
AS THE COLDER AIR FLOWS OVER THE SOMEWHAT WARMER WATERS. WITH THE
UPPER LEVEL TROUGH CROSSING THE AREA WILL EXPECT SOME INCREASED
CLOUD COVER...HOWEVER DO NOT EXPECT ANY PRECIPITATION.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
MODELS REMAIN IN GOOD AGREEMENT WITH ON AREA OF CONCERN LATE IN
THE LONG TERM. MODELS EXPECT A SYSTEM TO CROSS THE REGION DURING
THE MONDAY AND TUESDAY TIME FRAME. ALL MODELS AGREE ON A
SYSTEM...HOWEVER THERE ARE LARGE DIFFERENCES IN TIMING AND RUN TO
RUN CONSISTENCY WITH THIS SYSTEM. AS SUCH REMAIN ON THE
PESSIMISTIC SIDE AND KEPT CLOUDS AND POPS ON THE LOW SIDE OF
GUIDANCE.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
THE COLD AIR DAMMING WEDGE WAS LINGERING EARLY THIS MORNING.
SURFACE WINDS WERE LIGHT...BUT A RECENT ACARS SOUNDING INDICATED
WINDS OF 34 KNOTS AT 1200 FEET. INCLUDED LLWS EARLY THIS MORNING.
AS BOUNDARY LAYER WINDS CONTINUE TO INCREASE AHEAD OF THE
APPROACHING COLD FRONT THE WEDGE WILL ERODE THIS MORNING.
THE MAV AND MET MOS PLUS GFS LAMP INDICATE THE AFFECTS OF THE
WEDGE WILL DIMINISH WITH STRONGER WINDS MIXING DOWN TO THE SURFACE
BY 15Z. AREAS OF FOG AND STRATUS WILL LIKELY BECOME MAINLY
STATUS. USED THE MAV MOS AND GFS LAMP AND FORECASTED CEILINGS
RISING INTO THE MVFR CATEGORY LATE THIS MORNING. STRONG MIXING
SUPPORTS GUSTS TO AT LEAST 25 KNOTS IN THE AFTERNOON. THE MAV MOS
INDICATED CEILINGS RISING INTO THE VFR CATEGORY AND THIS APPEARED
REASONABLE BECAUSE OF THE EXPECTED MIXING. SHOWERS ASSOCIATED WITH
THE COLD FRONT WILL BRING LOWER CEILINGS AND VISIBILITIES AT TIMES THIS
AFTERNOON AND EVENING. THE NAM AND GFS ARE CLOSE WITH THE TIMING
WITH DRYING BEHIND THE FRONT THIS EVENING.
NO SIGNIFICANT IMPACTS EXPECTED DURING THE EXTENDED PERIOD.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...LAKE WIND ADVISORY FROM 10 AM THIS MORNING TO 8 PM EST THIS
EVENING FOR SCZ015-016-018-020>022-025>031-035>038-041.
GA...LAKE WIND ADVISORY FROM 10 AM THIS MORNING TO 8 PM EST THIS
EVENING FOR GAZ040-063>065-077.
&&
$$
SYNOPSIS...MP
NEAR TERM...MP
SHORT TERM...MP
LONG TERM...MP
AVIATION...JL
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1200 AM EST WED JAN 28 2009
.AVIATION...DISCUSSION FOR 6Z TAFS.
LOW PRESSURE MOVING FROM SW TN THRU KY TO WV WILL CONTINUE TO BRING
SNOW TO THE SITES AND SOME FZRAPL IN THE FIRST FEW HOURS TO KBMG.
CONDS WILL BE IFR OR WORSE DURING THE SNOW WHICH SHOULD LAST UNTIL
AT LEAST 15Z OR SO AND THEN TAPER TO FLURRIES BEFORE FINALLY ENDING
BY AROUND 18Z. TIME HTS SHOW SATURATION LASTING THRU THE NIGHT AND
WELL INTO THE MORNING. BEST FORCING ENDS BY AROUND 12Z OR SO SO SHUD
SEE AT LEAST VSBYS START TO IMPROVE THEN. WL ALLOW CLOUD DECKS TO
COME UP TO MVFR BY MID MORNING BASED ON SNDINGS BUT SHUD NOTE THAT
STICKING DOWN IN IFR IS A POSSIBILITY.
&&
.UPDATE...
01Z SFC MAP SHOWS THE 1014MB SFC LOW ACROSS NE MS WHICH IS A BIT
FURTHER NW THAN THE GFS/NAM HAD INDICATED ALTHOUGH NOT SIGNIFICANTLY
SO. PROFILERS SHOW 25-40KT LLJ STILL TARGETING SOUTHERN IN IN
RESPONSE TO THE INCREASING UPWARD MOTION AHEAD OF THE UPPER WAVE THE
COUPLED UPPER JET STRUCTURE ACROSS THE REGION. STRONGEST 3HR
PRESSURE FALLS ARE NOW OCCURRING ACROSS SE OH SO THE SFC LOW SHOULD
CONTINUE TO TRACK ACROSS CENTRAL TN AND EASTERN KY OVERNIGHT. WE
HAVE BEEN FOLLOWING THE SNOW/SLEET LINE AND THE SLEET/FREEZING RAIN
LINE MOST OF THE NIGHT AND OBS...REPORTS AND AIRCRAFT SOUNDINGS
SUGGEST THAT THIS LINE HAS MOVED AS FAR NORTH AS IT SHOULD GET
TONIGHT WITH SLEET JUST SOUTH OF IND AND SLEET/FREEZING RAIN
OCCURRING ALONG OR SOUTH OF A SULLIVAN INTO SOUTHERN MORGAN/JOHNSON
COUNTIES AND SOUTH OF SHELBYVILLE. GIVEN AMOUNT OF LIFT/MOISTURE AND
RADAR TRENDS WE HAVE RAISED THE ICE ACCUMULATION TO AROUND ONE HALF
INCH ACROSS THE SOUTH WHERE THE ICE ACCUMULATION SHOULD PERSIST
THROUGH 06Z BEFORE CHANGING TO SLEET/SNOW IN THE 6Z TO 9Z PERIOD.
MEANWHILE...ACROSS THE I-70 CORRIDOR AND POINTS NORTH...NATIONAL
RADAR IS SHOWING THE MAIN PRECIP SHIELD WITH THE UPPER WAVE NOW
APPROACHING THE CWA. RETURNS HAVE TAKEN ON A BANDED STRUCTURE ACROSS
IL WHERE VIS HAVE FALLEN TO AROUND OR JUST BELOW 1 MILE. THE 18Z
GFS/NAM KEPT THE LAYERED FRONTOGENETICAL FORCING SOUTH OF I-70
OVERNIGHT SO IT APPEARS THAT THIS FORCING IS OCCURRING SOMEWHAT
NORTH OF THE MODELS FCST. GIVEN THE AIR TEMPS IN THE TEENS SNOW
RATIOS WILL BE IN THE 15:1 RANGE WHICH SUGGESTS THAT ONE QUARTER
INCH OF LIQUID COULD RESULT IN UPWARDS OF 4-5 INCHES OF SNOW. THEY
ALREADY HAVE REPORTED 1 TO 2 INCHES OF SNOW AROUND THE LAF AREA AND
EXPECT MOST SPOTS ESPECIALLY SE OF LAF TO RECEIVE ANYWHERE FROM 4-5
INCHES AROUND OR N OF LAF TO PERHAPS AS MUCH AS 6-8 INCHES ACROSS
BOONE COUNTY BY WEDS AM SO WE WILL UPGRADE A FEW MORE COUNTIES NW OF
INDIANAPOLIS INTO A WARNING FOR SNOW AMOUNTS. NO SIG CHANGES TO SNOW
AMOUNTS FOR THE IND METRO AREA WHERE 3 INCHES HAVE ALREADY FALLEN
AND ANOTHER 3 TO 5 INCHES SHOULD FALL OVERNIGHT WHICH ADDS UP TO 6
TO 8 INCHES WITH SOME HIGHER AMOUNTS LIKELY FOR THE STORM BY EARLY
WEDS.
&&
.SHORT TERM.../TONIGHT INTO THURSDAY/
FORECAST FOCUS IS ON WINTER STORM.
AT 19Z MAIN UPPER TROF WAS ACROSS SWRN USA. INVERTED TROF EXTENDED
FM LOUISIANA INTO KY. SNOW WAS ACROSS NRN FA AND FZRA AND SNOW WAS
ACROSS SRN FA.
MODELS HAVE COME INTO BETTER AGREEMENT THIS RUN. WITH NO REAL
FRONTRUNNER...USED A BLEND OF THE SIMILAR SOLUTIONS.
NEAR 100 POPS TONIGHT AS FORCING AND MOISTURE WILL CONTINUE PRECIP.
UPPER AIR PROGS SHOW PLENTY OF MOISTURE NOT TOO FAR TO THE S OF
THE FA AND WATER VAPOR SATELLITE SHOWS SOME FEED FROM THE BAJA
AREA AS WELL. THERE WILL BE FRONTOGENETICAL FORCING TONIGHT WHICH
COULD CREATE BANDING. ALSO...HINTS OF SLANTWISE CONVECTION AS
WELL. UPPER JET WILL ADD TO LIFT. NOT COMPLETELY CONFIDENT IN THE
HIGH QPF GENERATED BY THE MODELS THOUGH...EVEN WITH THE MOISTURE
CONNECTIONS MENTIONED ABOVE. BEST MOISTURE TRANSPORT IS TO THE S
AND E OF THE FA. THUS WILL NOT GO QUITE AS HIGH AS MODEL QPF. EVEN
CUTTING MODEL QPF YIELDS ENOUGH SNOW FOR AN AVERAGE OF 6 INCH
SNOWS ALONG THE I-70 CORRIDOR NE INTO MUNCIE AREA. WILL EXPAND THE
WARNING N TO THESE AREAS. HIGHER AMOUNTS WILL OCCUR...ESPECIALLY
IN AREAS WHERE BANDING SETS UP. ACROSS SRN FA SNOW AMOUNTS MAY
NOT BE AS HIGH DUE TO PRECIP MIXING WITH SLEET AND FREEZING RAIN.
FOR NOW HAVE NOT INCLUDED TOO MUCH FREEZING RAIN PER MODEL
SOUNDINGS AND PRECIP CHANGING BACK TO SNOW ACROSS PARTS OF SRN IL.
WILL HAVE TO WATCH CLOSELY THOUGH. MAV TEMPS LOOK REASONABLE FOR
LOWS GIVEN EXPECTED CONDITIONS.
MODELS HINTING AT DEFORMATION ZONE EARLY ON WED WHICH WOULD LEAD
TO ANOTHER INCH OR SO BEFORE SNOW TAPERS OFF. KEEPING THE
WARNING/ADVISORY IN EFFECT UNTIL NOON STILL LOOKS OK. MAV TEMPS
LOOK GOOD AGAIN.
WEAK WAVE WILL BRING A SMALL CHANCE FOR SNOW AGAIN BY THU.
&&
.LONG TERM.../THURSDAY THROUGH MONDAY/
AS FOR THE EXTENDED...
LITTLE CHANGE IN THE EXTENDED AS THE ECMWF AND GFS AGREE THAT THE
COLD NW UPPER FLOW SHALL PERSIST. THE MODELS REMAIN CONSISTANT WITH
A WEAK TROUGH PUSHING ACRS THE RGN ON THURSDAY NIGHT AND
FRIDAY...THEN AGAIN ON SUNDAY NIGHT INTO MONDAY. BOTH SYSTEMS APPEAR
RATHER WEAK WITH SUSPECT MOISTURE AVAILABLE WITH THE THURSDAY
NIGHT/FRIDAY SYSTEM AND BETTER MOISTURE WITH THE SECOND SYSTEM BUT
WEAKER DYNAMICS.
CONTINUED THE TREND OF HIGHS AND LOW GENERALLY A FEW DEGREES BELOW
MEXMOS AS EXPECTED SNOW COVER AND COLD NW FLOW SHUD HAPMER MUCH IN
TEMPERATURE RISES.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 12 PM EST WEDNESDAY FOR INZ030-
036>049-051>057-060>065-067>072.
WINTER WEATHER ADVISORY UNTIL 12 PM EST WEDNESDAY FOR INZ021-028-
029-031-035.
&&
$$
UPDATE...CO
SHORT TERM...CS
LONG TERM...JP
AVIATION...CP
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
258 AM CST WED JAN 28 2009
.DISCUSSION...
ARCTIC AIR FINALLY GETTING SWEPT OUT OF CWA BY APPROACHING UPSTREAM
WAVE. SOME AREAS HAVE RISEN 25-30 DEGREES THE PAST 6 HOURS WITH
LISCO AT -13 AT ONE POINT AND NOW 22...KVTN -12/12. LIGHT NW SFC
FLOW INTO PLATTE VALLEY AHEAD OF THE SFC TROF/WIND SHIFT IN THE
PANHANDLE HAS ALLOWED TEMPS TO DROP TO BELOW ZERO BUT EXPECT THIS TO
CHANGE OVER NEXT HOUR OR SO. WATER VAPOR SHOWING CLIPPER SYTEM
MOVING THROUGH MANT ATTM WHILE ADDITIONAL NORTHERN STREAM ENERGY
DROPPING INTO NORTHERN ROCKIES WILL EVENTUALLY CARVE OUT A BROADER
TROF OVER CENTRAL AND EASTERN CONUS OVER NEXT 24-36 HOURS OR SO. AS
NW FLOW BECOMES ESTABLISHED TODAY...EXPECT WINDS TO INCREASE AS
COLDER AIR ARRIVES ALOFT AND LAPSE RATES INCREASE TO AID IN MIXING.
HAVE ADDED BLOWING SNOW TO ZONES WITH DRY NATURE TO SNOWPACK EXPECT
SOME DRIFTING AND BLOWING ISSUES...ESPECIALLY ACROSS
SANDHILLS...INCLUDING HWY 2 WHERE DEEPEST SNOW PACK EXISTS. THOUGHT
ABOUT ADV...BUT WITH TEMPS APPROACHING OR EXCEEDING
FREEZING...WONDER HOW THIS WILL AFFECT THE BLOWING AND DRIFTING AND
EXPECT VSBY CRIT WOULD NOT BE MET. WILL HILIGHT THESE CONCERNS IN
HWO INSTEAD OF HEADLINES. TEMPS PROBLEMATIC AS WELL NEXT FEW DAYS
AND MAV GUIDANCE LITTLE HELP. KEPT CLOSE TO CURRENT FORECAST WITH
TEMPS NEAR FREEZING OVER SNOWPACK AND SLIGHTLY WARMER IN FAR
SOUTH...WITH LEAN TOWARD MET GUIDANCE NEXT FEW DAYS. COLDEST AIR
PASSES OVHD LATE TONIGHT INTO MID DAY THURSDAY AS MAIN UPPER TROF
AXIS TRANSLATES THROUGH PLAINS. SOUNDING/X-SECTIONS SHOW FAIRLY
MOIST LAYER INCLUDING DENDRITIC BUT MINIMAL IF ANY LIFT WITH NW FLOW
IN PLACE. KEPT FLURRY WORDING FOR THURSDAY AM AS CONFIDENCE NOT HIGH
FOR ANY ACCUMULATIONS. AS TROF MOVES EAST AND RIDGE BUILDS IN AHEAD
OF NEXT FAST MOVING TROF SLATED FOR LATE WEEKEND...TEMPS SHOULD
BEGIN A REBOUND FRIDAY INTO SATURDAY. SNOWPACK AND RESIDUAL MOISTURE
FROM MELTING SHOULD HAMPER TRUE WARMUP LIKE LAST WEEK AND HAVE
TEMPERED HIGH DOWN A FEW DEGREES...WITH COLD BIAS CONTINUING OVER
SANDHILLS SNOWPACK. COLD FRONT SAT NIGHT LOOKS TO BE FAIRLY DRY AS
THIS IS MORE OF A CLIPPER TYPE SYSTEM AND HAVE KEPT FORECAST
DRY...BUT KNOCKED TEMPS DOWN QUITE A FEW DEGREES SUNDAY WITH
AGREEMENT BETWEEN NEWEST GFS/EURO. NOT SURE WHAT EFFECT THE WARM
SPELL WILL HAVE ON ICE BREAK UP ON AREA RIVERS BUT ANOTHER THING TO
BE MONITORED OVER NEXT SEVERAL DAYS.
&&
.AVIATION...
VFR CONDITIONS LOOK TO HOLD WITH HIGH CLOUDS MOVING OVHD...STRONG NW
WINDS THIS AFTERNOON MAY HAMPER LIGHT AIRCRAFT OPERATIONS. LIGHT
PRECIPITATION OR VIRGA MAY BE PRESENT NEAR KVTN TAF SITE AS WELL.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
13/POWER
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1015 AM EST WED JAN 28 2009
.SYNOPSIS...
A WARM FRONT WILL MOVE NORTH ACROSS THE REGION THIS MORNING...
THEN BLUSTERY SOUTHWEST FLOW WILL BRING MILDER TEMPERATURES FOR
TODAY. A COLD FRONT WILL MOVE SOUTHEAST THROUGH THE AREA THIS
AFTERNOON INTO EARLY EVENING...BRINGING WIDESPREAD SHOWERS.
BEHIND THE FRONT...DRIER AND COOLER CONDITIONS WILL FOLLOW ON
THURSDAY THROUGH FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM WEDNESDAY...
THE WARM FRONT HAS MADE RAPID PROGRESS THROUGH THE AREA IN THE
PAST FEW HOURS...AND VISIBILITIES HAVE SIGNIFICANTLY IMPROVED
ACROSS THE DENSE FOG ADVISORY AREA...THEREFORE...THE DFA HAS BEEN
CANCELLED. ALTHOUGH DENSE FOG WILL REMAIN POSSIBLE ACROSS THE FAR
NORTHERN CWA ADJACENT TO THE NC/VA BORDER THROUGH 11 AM...
VISIBILITIES THERE SHOULD ALSO RAPIDLY IMPROVE IN THE NEXT HOUR OR
SO AS THE WARM FRONT CONTINUES TO SURGE NORTH...AND A SPECIAL
WEATHER STATEMENT PREVIOUSLY ISSUED WILL BE ALLOWED TO COVER THE
BRIEF DENSE FOG POTENTIAL REMAINING IN THE NORTH THROUGH 11 AM
THIS MORNING. -VINCENT
PREVIOUSLY... AS OF 230 AM WEDNESDAY...
FOR TODAY: STILL EXPECT THIS TO BECOME A MILD AND BLUSTERY DAY WITH
THE BEST RAIN CHANCES HOLDING OFF UNTIL AFTERNOON. A SOMEWHAT
COMPLEX SURFACE PATTERN IS IN PLACE WITH A DIFFUSE WEDGE FRONT
SITTING THROUGH THE NC PIEDMONT WITH A MORE SUBSTANTIAL FRONT
FARTHER SOUTH ACROSS SRN SC... AND THE STRONG COLD FRONT BACK ACROSS
CENTRAL TN. SURFACE WINDS REMAIN CALM TO LIGHT NE WITHIN THE
RESIDUAL STABLE POOL OVER THE PIEDMONT AND LIGHT FROM THE SE OVER
SRN/ERN NC. BUT WINDS ABOVE 1500 FT AGL HAVE ALREADY BEGUN TO
INCREASE AS NOTED ON AMDAR AIRCRAFT SOUNDINGS... AND THE LATEST RUC
SIMILARLY SHOWS WINDS INCREASING TO 30 KTS TOWARD DAYBREAK AROUND
1500-2000 FT. THE SURFACE BASED STABLE LAYER... HOWEVER... SHOULD
CONTINUE TO KEEP THESE STRONG WINDS UP OFF THE SURFACE THROUGH MID
MORNING... WHEN FORECAST SOUNDINGS INDICATE SUFFICIENT TURBULENT
MIXING TO SCOUR OUT THIS RESIDUAL STABLE POOL. ONCE IT DOES...
PROBABLY NOT UNTIL LATE THIS MORNING... SUSTAINED WINDS ARE LIKELY
TO APPROACH 20 KTS (23 MPH) WITH GUSTS TO 35 KTS (40 MPH) POSSIBLE.
THIS IS CLOSE TO WIND ADVISORY CRITERIA (GUSTS OVER 40 KTS/46 MPH).
BUT HISTORICALLY IT`S BEEN DIFFICULT TO REACH ADVISORY CRITERIA
WINDS IN WARM ADVECTION SITUATIONS. THEY MORE OFTEN HAVE OCCURRED
WITHIN STRONG COLD AIR ADVECTION. WILL ISSUE A SPECIAL WEATHER
STATEMENT TO HIGHLIGHT THE BLUSTERY WINDS... BUT WILL HOLD OFF ON AN
ADVISORY FOR NOW. REGARDING THE EXPECTED RAIN... THIS SYSTEM RETAINS
AN ANAFRONTAL STRUCTURE... THUS THE BULK OF THE RAINFALL IS EXPECTED
TO BE NEAR OR JUST AFTER COLD FRONTAL PASSAGE... WHICH SHOULD OCCUR
BETWEEN 2 AND 6 PM. AHEAD OF THE FRONT... AREAS OF DRIZZLE AND FOG
WILL PERSIST THROUGH DAYBREAK. ONCE WE ARE FULLY IN THE WARM
SECTOR... WITH LIMITED FORCING... ONLY PATCHY SHOWERS ARE EXPECTED
THROUGH NOON. IT SHOULD BE NOTED THAT THE LATEST NAM SHOWS THE
STABLE POOL HOLDING ON IN THE TRIAD UNTIL COLD FRONT PASSAGE... AND
THIS IS CERTAINLY POSSIBLE GIVEN THE 1000-FT-DEEP STABLE LAYER SHOWN
ON THE 00Z GSO SOUNDING. AT ANY RATE... RAIN AMOUNTS WILL BE LIGHT
THIS MORNING AND LOW CHANCE POPS WILL SUFFICE. THEN THIS
AFTERNOON... AS FORCING FOR ASCENT INCREASES AS THE UPPER JET`S
RIGHT ENTRANCE REGION APPROACHES ALONG WITH STRONG LOW LEVEL
MOISTURE TRANSPORT AND HIGH PRECIPITABLE WATER... HAVE POPS RISING
TO CATEGORICAL WEST/CHANCE EAST THROUGH MID AFTERNOON... THEN
SHIFTING TO CATEGORICAL EAST AND LOWERING POPS WEST. INSTABILITY...
ESPECIALLY WITHIN THE MIXED PHASE REGION ALOFT WHERE LIGHTNING IS
PRODUCED... STILL LOOKS VERY MINOR AND WILL LEAVE OUT THE MENTION OF
THUNDER... ALTHOUGH A STRIKE OR TWO IS POSSIBLE OVER THE SOUTHERN
COASTAL PLAIN. STORM TOTAL RAINFALL IS EXPECTED TO RANGE FROM A
THIRD TO AROUND A HALF INCH. TEMPERATURES HAVE HELD FAIRLY STEADY
EVERYWHERE OVERNIGHT... BUT ONCE THE WARM ADVECTION DEEPENS AND
INCREASES LATER THIS MORNING... READINGS SHOULD RISE INTO THE MID
60S-AROUND 70 OVER ALL BUT THE FAR NW COUNTIES... WHERE THE
POSSIBILITY OF THE LINGERING STABLE POOL IS GREAT ENOUGH TO HOLD
HIGH TEMPS TO 55-60.
FOR TONIGHT: WINDS SHOULD DIMINISH QUICKLY BEHIND THE FRONT. WILL
KEEP POPS IN THE SOUTHEAST CWA THROUGH MID EVENING UNTIL THE FRONT
PUSHES OFF THE COAST. THE NORTHWEST CWA SHOULD FEEL THE DRYING
EFFECTS OF THE DOWNSLOPE FLOW... HOWEVER THE REST OF THE AREA MAY
SEE LINGERING CLOUDS FOR MUCH OF THE NIGHT AS THE 850 MB FLOW
REMAINS FROM THE WSW THROUGH DAYBREAK THURSDAY. ALSO... WE WILL
REMAIN ON THE SE SIDE OF THE 140+ KT UPPER JET CORE... LIKELY
MEANING A PERSISTENT STREAM OF HIGH CLOUDS. HAVE RAISED SKY COVER
QUITE A BIT OVER THE SOUTHERN AND EASTERN CWA TONIGHT. THE HIGH
PRESSURE AREA BEGINS TO BUILD INTO NC FROM THE WEST... BUT THE BULK
OF THE MUCH CHILLIER AIR APPEARS TO GET HELD UP BY THE APPALACHIANS.
WILL HAVE LOWS FROM 30 TO 41 NW TO SE... CLOSE TO THE EXISTING
FORECAST. -GIH
&&
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
AS OF 255 AM WEDNESDAY...
FOR THURSDAY: WEAK HIGH PRESSURE TRIES TO BUILD IN BEHIND THE FRONT
FROM THE NW... ALTHOUGH A TRAILING LOW PRESSURE TROUGH IS LIKELY TO
SETTLE NEAR OR JUST SOUTH OF THE NC/SC STATE LINE THROUGH THURSDAY.
DESPITE INTENSE DRYING TAKING PLACE IN THE MID LEVELS... WE
ANTICIPATE RESIDUAL CLOUDINESS BELOW THE SUBSIDENCE INVERSION
ALOFT... AROUND 3000 FT AGL... THROUGH AT LEAST THURSDAY MORNING
MAINLY OVER THE SOUTHEAST HALF OF THE CWA. ALSO... WHILE THE
STRONGEST PORTIONS OF THE UPPER JET WILL BE TO OUR NE AND SW THROUGH
THURSDAY... SWRLY SPEEDS ALOFT WILL BE STRONG ENOUGH FOR WEAK
UPGLIDE AT 330 K OVER CENTRAL NC... WHICH SHOULD GENERATE SOME HIGH
CLOUDS. BUT IN GENERAL... IT SHOULD BE A QUIET WEATHER DAY WITH SOME
FILTERED SUNSHINE OVER THE NW IN THE AFTERNOON. WITH THE INFLUX OF
COLD AIR LIKELY TO BE HELD UP TO SOME DEGREE BY THE MOUNTAINS AS
NOTED ABOVE... EXPECT RATHER SEASONABLE TEMPERATURES WITH HIGHS IN
THE UPPER 40S TO LOWER 50S.
FOR THURSDAY NIGHT THROUGH FRIDAY NIGHT: WEAK HIGH PRESSURE AND VERY
LIGHT N-NE SURFACE FLOW WILL PERSIST OVER THE REGION THROUGH
THURSDAY NIGHT. A VEIL OF HIGH CLOUDS SHOULD LINGER WITH A 140 KT
JET SITTING OVERHEAD... AND AS 850 MB WINDS BACK TO THE SW...
SCATTERED STRATOCUMULUS CLOUDS ARE PROBABLE TOWARD MORNING. HAVE
BUMPED LOWS UP A TAD TO 29-33... ALTHOUGH THE WEAK BOUNDARY LAYER
FLOW SHOULD ALLOW A GOOD SHALLOW INVERSION TO DEVELOP WITH NOCTURNAL
COOLING AT THE GROUND. THEN ON FRIDAY/FRIDAY NIGHT... THE MEAN
TROUGH AXIS WHICH RELOADS FROM THE GREAT LAKES THROUGH THE LOWER
MISS VALLEY THURSDAY NIGHT WILL SHIFT EASTWARD... SWINGING THROUGH
NC FRIDAY NIGHT. A SHEARED VORTICITY MAXIMUM SWINGING THROUGH THE
SOUTHEAST SIDE OF THIS TROUGH IS PROGGED BY THE NAM/GFS/ECMWF/GEM TO
SWEEP NORTHEASTWARD THROUGH CENTRAL/ERN NC FRIDAY AFTERNOON.
FORECAST SOUNDINGS SHOW NICELY STEEPENING SURFACE-750 MB LAPSE
RATES... HOWEVER THE MODELS HAVE TRENDED DRIER SINCE YESTERDAY`S
RUNS. WILL LEAVE THE FORECAST DRY. THE UPPER JET FINALLY MOVES WELL
EAST OF OUR AREA FRIDAY NIGHT AS THE UPPER TROUGH AXIS SWINGS
THROUGH... AND EXPECT MOSTLY CLEAR SKIES AND A STABLE/DRY COLUMN. WE
COULD SEE A PERIOD OF GUSTY WINDS FRIDAY EVENING INTO THE EARLY
OVERNIGHT AS THE THERMAL TROUGH PASSES THROUGH. LOW LEVEL
THICKNESSES HOLD NEAR NORMAL FRIDAY... SO EXPECT HIGHS OF 48-54.
LOWS 20-26 FRIDAY NIGHT AS THICKNESSES PLUMMET. -GIH
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
AS OF 330 AM WEDNESDAY...
FOR SATURDAY THROUGH SUNDAY: THE WEEKEND SHOULD BE QUIET WITH
SHORTWAVE RIDGING ALOFT... BETWEEN THE TROUGH SHIFTING OFFSHORE AND
THE NEXT SYSTEM DROPPING THROUGH THE MIDWEST. WITH HIGH PRESSURE
OVERHEAD... WE SHOULD SEE LITTLE IN THE WAY OF CLOUDS. THICKNESSES
REBOUND NICELY FROM AROUND 35 M BELOW NORMAL SATURDAY MORNING...
HEADING BACK TO JUST ABOVE NORMAL BY LATE SUNDAY. NO MAJOR CHANGE TO
TEMPS... HIGHS 43-48 SATURDAY AND 51-56 SUNDAY.
FOR SUNDAY NIGHT-TUESDAY (UPDATED FOR 06Z MODEL DATA): MID LEVEL
TROUGHING AMPLIFIES OVER CENTRAL NOAM SUNDAY NIGHT... AND THIS
TROUGH PUSHES EASTWARD THROUGH EARLY TUESDAY... AMPLIFYING AND
TAKING ON A SLIGHTLY NEGATIVE TILT. THE 00Z GFS/ECMWF DIFFER ON
TIMING BUT BOTH SHOW A VORTEX CLOSING OFF OVER THE INTERIOR
NORTHEAST... AND THE 06Z GFS IS EVEN STRONGER... CLOSING OFF THE
VORTEX OVER VA. THE GFS/ECMWF BOTH SHOW SURFACE LOW PRESSURE
DEVELOPING OVER THE EASTERN GULF AND INTENSIFYING AS IT TRACKS UP
THROUGH NC... WITH THE 00Z AND 06Z GFS RUNS ESPECIALLY INTENSE WITH
THIS FEATURE. THE GFS/ECMWF BOTH SHOW INTENSE MOISTURE TRANSPORT
INTO THE SOUTHEAST AND CAROLINAS AHEAD OF THIS GULF LOW... AND THE
FORECAST THERMAL PROFILES HINT AT POTENTIAL WINTRY WEATHER OVER THE
WESTERN HALF OF THE STATE. WHILE IT IS FAR TOO EARLY TO MAKE A CALL
ON PRECIP TYPE OR ON THE DETAILS OF SUCH A PATTERN... WILL INCREASE
POPS UP TO LOW CHANCE MONDAY AND 30-40% CHANCE MONDAY NIGHT...
DECREASING A BIT TUESDAY DUE TO TIMING UNCERTAINTY. EXPECT HIGHS IN
THE MID-UPPER 50S MONDAY AND LOWER 50S TUESDAY... BUT THESE COULD
CHANGE QUITE A BIT IF WIDESPREAD PRECIP COMES TO PASS. -GIH
&&
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
AS OF 740 AM WEDNESDAY...
LIFR CONDITIONS IN STRATUS...DRIZZLE AND FOG WILL PERSIST THROUGH
LATE MORNING (~15/16Z) AS SOUTHWEST FLOW JUST OFF THE SURFACE
OVERRUNS COOL...MOIST NORTHEAST FLOW AT THE SURFACE. CONDITIONS WILL
LIFT TO MVFR LATE MORNING TO EARLY AFTERNOON AS A WARM FRONT PUSHES
NORTH THROUGH THE REGION. LOW LEVEL WIND SHEAR WILL BE A THREAT
THROUGH NOON (~17) AS THE FLOW ABOVE 15 HUNDRED FEET STRENGTHENS TO
40 TO 50 KNOTS... AND BEGINS TO MIX DOWN TO THE SURFACE.
A COLD FRONT WILL APPROACH AND MOVE ACROSS CENTRAL NORTH CAROLINA
BETWEEN 15Z THIS MORNING AND 00Z THURSDAY. AS THE GRADIENT TIGHTENS
SURFACE WINDS COULD GUST TO AT LEAST 35 KNOTS DURING THE AFTERNOON.
WITH THE FRONTAL PASSAGE WILL ALSO COME THE THREAT OF MVFR CEILINGS
IN RAIN.
SOUNDING DATA SHOW RAPID DRYING BEHIND THE FRONT AS HIGH PRESSURE
BUILDS IN NORTH CAROLINA FROM THE WEST... THEREFORE WE CAN EXPECT A
CLEARING TREND IN THE WEST AFTER 00Z TONIGHT... SPREADING TO THE
EAST BY 09Z THURSDAY MORNING.
HIGH PRESSURE WILL CONTROL THE AREAS WEATHER THROUGH SUNDAY...
HOWEVER AN UPPER TROUGH MOVING ACROSS THE REGION FRIDAY THROUGH
EARLY SATURDAY MAY HAVE ENOUGH MOISTURE WITH IT TO ENHANCE THE
DEVELOPMENT OF CLOUDS BETWEEN 35 HUNDRED AND 5 THOUSAND FEET.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT/HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...HARTFIELD
AVIATION...RHJ
AREA FORECAST DISCUSSION
NWS RALEIGH NC
740 AM EST WED JAN 28 2009
.SYNOPSIS...
A WARM FRONT WILL SLOWLY MOVE NORTH ACROSS THE REGION THROUGH THIS
MORNING... THEN BLUSTERY SOUTHWEST FLOW WILL BRING MILDER
TEMPERATURES FOR TODAY. A COLD FRONT WILL MOVE SOUTHEAST THROUGH THE
AREA THIS AFTERNOON INTO EARLY EVENING... BRINGING WIDESPREAD
SHOWERS. BEHIND THE FRONT... DRIER AND COOLER CONDITIONS WILL FOLLOW
ON THURSDAY THROUGH FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 605 AM WEDNESDAY...
THE FOG ACROSS THE AREA HAS BECOME RATHER DENSE OVER A WIDE AREA
OVER THE LAST HOUR... SO HAVE GONE AHEAD WITH A DENSE FOG ADVISORY
UNTIL 10 AM FOR ALL BUT THE NORTHWEST AND FAR NORTH SECTIONS OF THE
CWA.
PREVIOUSLY... AS OF 230 AM WEDNESDAY...
FOR TODAY: STILL EXPECT THIS TO BECOME A MILD AND BLUSTERY DAY WITH
THE BEST RAIN CHANCES HOLDING OFF UNTIL AFTERNOON. A SOMEWHAT
COMPLEX SURFACE PATTERN IS IN PLACE WITH A DIFFUSE WEDGE FRONT
SITTING THROUGH THE NC PIEDMONT WITH A MORE SUBSTANTIAL FRONT
FARTHER SOUTH ACROSS SRN SC... AND THE STRONG COLD FRONT BACK ACROSS
CENTRAL TN. SURFACE WINDS REMAIN CALM TO LIGHT NE WITHIN THE
RESIDUAL STABLE POOL OVER THE PIEDMONT AND LIGHT FROM THE SE OVER
SRN/ERN NC. BUT WINDS ABOVE 1500 FT AGL HAVE ALREADY BEGUN TO
INCREASE AS NOTED ON AMDAR AIRCRAFT SOUNDINGS... AND THE LATEST RUC
SIMILARLY SHOWS WINDS INCREASING TO 30 KTS TOWARD DAYBREAK AROUND
1500-2000 FT. THE SURFACE BASED STABLE LAYER... HOWEVER... SHOULD
CONTINUE TO KEEP THESE STRONG WINDS UP OFF THE SURFACE THROUGH MID
MORNING... WHEN FORECAST SOUNDINGS INDICATE SUFFICIENT TURBULENT
MIXING TO SCOUR OUT THIS RESIDUAL STABLE POOL. ONCE IT DOES...
PROBABLY NOT UNTIL LATE THIS MORNING... SUSTAINED WINDS ARE LIKELY
TO APPROACH 20 KTS (23 MPH) WITH GUSTS TO 35 KTS (40 MPH) POSSIBLE.
THIS IS CLOSE TO WIND ADVISORY CRITERIA (GUSTS OVER 40 KTS/46 MPH).
BUT HISTORICALLY IT`S BEEN DIFFICULT TO REACH ADVISORY CRITERIA
WINDS IN WARM ADVECTION SITUATIONS. THEY MORE OFTEN HAVE OCCURRED
WITHIN STRONG COLD AIR ADVECTION. WILL ISSUE A SPECIAL WEATHER
STATEMENT TO HIGHLIGHT THE BLUSTERY WINDS... BUT WILL HOLD OFF ON AN
ADVISORY FOR NOW. REGARDING THE EXPECTED RAIN... THIS SYSTEM RETAINS
AN ANAFRONTAL STRUCTURE... THUS THE BULK OF THE RAINFALL IS EXPECTED
TO BE NEAR OR JUST AFTER COLD FRONTAL PASSAGE... WHICH SHOULD OCCUR
BETWEEN 2 AND 6 PM. AHEAD OF THE FRONT... AREAS OF DRIZZLE AND FOG
WILL PERSIST THROUGH DAYBREAK. ONCE WE ARE FULLY IN THE WARM
SECTOR... WITH LIMITED FORCING... ONLY PATCHY SHOWERS ARE EXPECTED
THROUGH NOON. IT SHOULD BE NOTED THAT THE LATEST NAM SHOWS THE
STABLE POOL HOLDING ON IN THE TRIAD UNTIL COLD FRONT PASSAGE... AND
THIS IS CERTAINLY POSSIBLE GIVEN THE 1000-FT-DEEP STABLE LAYER SHOWN
ON THE 00Z GSO SOUNDING. AT ANY RATE... RAIN AMOUNTS WILL BE LIGHT
THIS MORNING AND LOW CHANCE POPS WILL SUFFICE. THEN THIS
AFTERNOON... AS FORCING FOR ASCENT INCREASES AS THE UPPER JET`S
RIGHT ENTRANCE REGION APPROACHES ALONG WITH STRONG LOW LEVEL
MOISTURE TRANSPORT AND HIGH PRECIPITABLE WATER... HAVE POPS RISING
TO CATEGORICAL WEST/CHANCE EAST THROUGH MID AFTERNOON... THEN
SHIFTING TO CATEGORICAL EAST AND LOWERING POPS WEST. INSTABILITY...
ESPECIALLY WITHIN THE MIXED PHASE REGION ALOFT WHERE LIGHTNING IS
PRODUCED... STILL LOOKS VERY MINOR AND WILL LEAVE OUT THE MENTION OF
THUNDER... ALTHOUGH A STRIKE OR TWO IS POSSIBLE OVER THE SOUTHERN
COASTAL PLAIN. STORM TOTAL RAINFALL IS EXPECTED TO RANGE FROM A
THIRD TO AROUND A HALF INCH. TEMPERATURES HAVE HELD FAIRLY STEADY
EVERYWHERE OVERNIGHT... BUT ONCE THE WARM ADVECTION DEEPENS AND
INCREASES LATER THIS MORNING... READINGS SHOULD RISE INTO THE MID
60S-AROUND 70 OVER ALL BUT THE FAR NW COUNTIES... WHERE THE
POSSIBILITY OF THE LINGERING STABLE POOL IS GREAT ENOUGH TO HOLD
HIGH TEMPS TO 55-60.
FOR TONIGHT: WINDS SHOULD DIMINISH QUICKLY BEHIND THE FRONT. WILL
KEEP POPS IN THE SOUTHEAST CWA THROUGH MID EVENING UNTIL THE FRONT
PUSHES OFF THE COAST. THE NORTHWEST CWA SHOULD FEEL THE DRYING
EFFECTS OF THE DOWNSLOPE FLOW... HOWEVER THE REST OF THE AREA MAY
SEE LINGERING CLOUDS FOR MUCH OF THE NIGHT AS THE 850 MB FLOW
REMAINS FROM THE WSW THROUGH DAYBREAK THURSDAY. ALSO... WE WILL
REMAIN ON THE SE SIDE OF THE 140+ KT UPPER JET CORE... LIKELY
MEANING A PERSISTENT STREAM OF HIGH CLOUDS. HAVE RAISED SKY COVER
QUITE A BIT OVER THE SOUTHERN AND EASTERN CWA TONIGHT. THE HIGH
PRESSURE AREA BEGINS TO BUILD INTO NC FROM THE WEST... BUT THE BULK
OF THE MUCH CHILLIER AIR APPEARS TO GET HELD UP BY THE APPALACHIANS.
WILL HAVE LOWS FROM 30 TO 41 NW TO SE... CLOSE TO THE EXISTING
FORECAST. -GIH
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 255 AM WEDNESDAY...
FOR THURSDAY: WEAK HIGH PRESSURE TRIES TO BUILD IN BEHIND THE FRONT
FROM THE NW... ALTHOUGH A TRAILING LOW PRESSURE TROUGH IS LIKELY TO
SETTLE NEAR OR JUST SOUTH OF THE NC/SC STATE LINE THROUGH THURSDAY.
DESPITE INTENSE DRYING TAKING PLACE IN THE MID LEVELS... WE
ANTICIPATE RESIDUAL CLOUDINESS BELOW THE SUBSIDENCE INVERSION
ALOFT... AROUND 3000 FT AGL... THROUGH AT LEAST THURSDAY MORNING
MAINLY OVER THE SOUTHEAST HALF OF THE CWA. ALSO... WHILE THE
STRONGEST PORTIONS OF THE UPPER JET WILL BE TO OUR NE AND SW THROUGH
THURSDAY... SWRLY SPEEDS ALOFT WILL BE STRONG ENOUGH FOR WEAK
UPGLIDE AT 330 K OVER CENTRAL NC... WHICH SHOULD GENERATE SOME HIGH
CLOUDS. BUT IN GENERAL... IT SHOULD BE A QUIET WEATHER DAY WITH SOME
FILTERED SUNSHINE OVER THE NW IN THE AFTERNOON. WITH THE INFLUX OF
COLD AIR LIKELY TO BE HELD UP TO SOME DEGREE BY THE MOUNTAINS AS
NOTED ABOVE... EXPECT RATHER SEASONABLE TEMPERATURES WITH HIGHS IN
THE UPPER 40S TO LOWER 50S.
FOR THURSDAY NIGHT THROUGH FRIDAY NIGHT: WEAK HIGH PRESSURE AND VERY
LIGHT N-NE SURFACE FLOW WILL PERSIST OVER THE REGION THROUGH
THURSDAY NIGHT. A VEIL OF HIGH CLOUDS SHOULD LINGER WITH A 140 KT
JET SITTING OVERHEAD... AND AS 850 MB WINDS BACK TO THE SW...
SCATTERED STRATOCUMULUS CLOUDS ARE PROBABLE TOWARD MORNING. HAVE
BUMPED LOWS UP A TAD TO 29-33... ALTHOUGH THE WEAK BOUNDARY LAYER
FLOW SHOULD ALLOW A GOOD SHALLOW INVERSION TO DEVELOP WITH NOCTURNAL
COOLING AT THE GROUND. THEN ON FRIDAY/FRIDAY NIGHT... THE MEAN
TROUGH AXIS WHICH RELOADS FROM THE GREAT LAKES THROUGH THE LOWER
MISS VALLEY THURSDAY NIGHT WILL SHIFT EASTWARD... SWINGING THROUGH
NC FRIDAY NIGHT. A SHEARED VORTICITY MAXIMUM SWINGING THROUGH THE
SOUTHEAST SIDE OF THIS TROUGH IS PROGGED BY THE NAM/GFS/ECMWF/GEM TO
SWEEP NORTHEASTWARD THROUGH CENTRAL/ERN NC FRIDAY AFTERNOON.
FORECAST SOUNDINGS SHOW NICELY STEEPENING SURFACE-750 MB LAPSE
RATES... HOWEVER THE MODELS HAVE TRENDED DRIER SINCE YESTERDAY`S
RUNS. WILL LEAVE THE FORECAST DRY. THE UPPER JET FINALLY MOVES WELL
EAST OF OUR AREA FRIDAY NIGHT AS THE UPPER TROUGH AXIS SWINGS
THROUGH... AND EXPECT MOSTLY CLEAR SKIES AND A STABLE/DRY COLUMN. WE
COULD SEE A PERIOD OF GUSTY WINDS FRIDAY EVENING INTO THE EARLY
OVERNIGHT AS THE THERMAL TROUGH PASSES THROUGH. LOW LEVEL
THICKNESSES HOLD NEAR NORMAL FRIDAY... SO EXPECT HIGHS OF 48-54.
LOWS 20-26 FRIDAY NIGHT AS THICKNESSES PLUMMET. -GIH
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 330 AM WEDNESDAY...
FOR SATURDAY THROUGH SUNDAY: THE WEEKEND SHOULD BE QUIET WITH
SHORTWAVE RIDGING ALOFT... BETWEEN THE TROUGH SHIFTING OFFSHORE AND
THE NEXT SYSTEM DROPPING THROUGH THE MIDWEST. WITH HIGH PRESSURE
OVERHEAD... WE SHOULD SEE LITTLE IN THE WAY OF CLOUDS. THICKNESSES
REBOUND NICELY FROM AROUND 35 M BELOW NORMAL SATURDAY MORNING...
HEADING BACK TO JUST ABOVE NORMAL BY LATE SUNDAY. NO MAJOR CHANGE TO
TEMPS... HIGHS 43-48 SATURDAY AND 51-56 SUNDAY.
FOR SUNDAY NIGHT-TUESDAY (UPDATED FOR 06Z MODEL DATA): MID LEVEL
TROUGHING AMPLIFIES OVER CENTRAL NOAM SUNDAY NIGHT... AND THIS
TROUGH PUSHES EASTWARD THROUGH EARLY TUESDAY... AMPLIFYING AND
TAKING ON A SLIGHTLY NEGATIVE TILT. THE 00Z GFS/ECMWF DIFFER ON
TIMING BUT BOTH SHOW A VORTEX CLOSING OFF OVER THE INTERIOR
NORTHEAST... AND THE 06Z GFS IS EVEN STRONGER... CLOSING OFF THE
VORTEX OVER VA. THE GFS/ECMWF BOTH SHOW SURFACE LOW PRESSURE
DEVELOPING OVER THE EASTERN GULF AND INTENSIFYING AS IT TRACKS UP
THROUGH NC... WITH THE 00Z AND 06Z GFS RUNS ESPECIALLY INTENSE WITH
THIS FEATURE. THE GFS/ECMWF BOTH SHOW INTENSE MOISTURE TRANSPORT
INTO THE SOUTHEAST AND CAROLINAS AHEAD OF THIS GULF LOW... AND THE
FORECAST THERMAL PROFILES HINT AT POTENTIAL WINTRY WEATHER OVER THE
WESTERN HALF OF THE STATE. WHILE IT IS FAR TOO EARLY TO MAKE A CALL
ON PRECIP TYPE OR ON THE DETAILS OF SUCH A PATTERN... WILL INCREASE
POPS UP TO LOW CHANCE MONDAY AND 30-40% CHANCE MONDAY NIGHT...
DECREASING A BIT TUESDAY DUE TO TIMING UNCERTAINTY. EXPECT HIGHS IN
THE MID-UPPER 50S MONDAY AND LOWER 50S TUESDAY... BUT THESE COULD
CHANGE QUITE A BIT IF WIDESPREAD PRECIP COMES TO PASS. -GIH
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AS OF 740 AM WEDNESDAY...
LIFR CONDITIONS IN STRATUS...DRIZZLE AND FOG WILL PERSIST THROUGH
LATE MORNING (~15/16Z) AS SOUTHWEST FLOW JUST OFF THE SURFACE
OVERRUNS COOL...MOIST NORTHEAST FLOW AT THE SURFACE. CONDITIONS WILL
LIFT TO MVFR LATE MORNING TO EARLY AFTERNOON AS A WARM FRONT PUSHES
NORTH THROUGH THE REGION. LOW LEVEL WIND SHEAR WILL BE A THREAT
THROUGH NOON (~17) AS THE FLOW ABOVE 15 HUNDRED FEET STRENGTHENS TO
40 TO 50 KNOTS... AND BEGINS TO MIX DOWN TO THE SURFACE.
A COLD FRONT WILL APPROACH AND MOVE ACROSS CENTRAL NORTH CAROLINA
BETWEEN 15Z THIS MORNING AND 00Z THURSDAY. AS THE GRADIENT TIGHTENS
SURFACE WINDS COULD GUST TO AT LEAST 35 KNOTS DURING THE AFTERNOON.
WITH THE FRONTAL PASSAGE WILL ALSO COME THE THREAT OF MVFR CEILINGS
IN RAIN.
SOUNDING DATA SHOW RAPID DRYING BEHIND THE FRONT AS HIGH PRESSURE
BUILDS IN NORTH CAROLINA FROM THE WEST... THEREFORE WE CAN EXPECT A
CLEARING TREND IN THE WEST AFTER 00Z TONIGHT... SPREADING TO THE
EAST BY 09Z THURSDAY MORNING.
HIGH PRESSURE WILL CONTROL THE AREAS WEATHER THROUGH SUNDAY...
HOWEVER AN UPPER TROUGH MOVING ACROSS THE REGION FRIDAY THROUGH
EARLY SATURDAY MAY HAVE ENOUGH MOISTURE WITH IT TO ENHANCE THE
DEVELOPMENT OF CLOUDS BETWEEN 35 HUNDRED AND 5 THOUSAND FEET.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR
NCZ026>028-041>043-073>078-083>086-088-089.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...HARTFIELD
AVIATION...RHJ
AREA FORECAST DISCUSSION
NWS RALEIGH NC
605 AM EST WED JAN 28 2009
.SYNOPSIS...
A WARM FRONT WILL SLOWLY MOVE NORTH ACROSS THE REGION THROUGH THIS
MORNING... THEN BLUSTERY SOUTHWEST FLOW WILL BRING MILDER
TEMPERATURES FOR TODAY. A COLD FRONT WILL MOVE SOUTHEAST THROUGH THE
AREA THIS AFTERNOON INTO EARLY EVENING... BRINGING WIDESPREAD
SHOWERS. BEHIND THE FRONT... DRIER AND COOLER CONDITIONS WILL FOLLOW
ON THURSDAY THROUGH FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 605 AM WEDNESDAY...
THE FOG ACROSS THE AREA HAS BECOME RATHER DENSE OVER A WIDE AREA
OVER THE LAST HOUR... SO HAVE GONE AHEAD WITH A DENSE FOG ADVISORY
UNTIL 10 AM FOR ALL BUT THE NORTHWEST AND FAR NORTH SECTIONS OF THE
CWA.
PREVIOUSLY... AS OF 230 AM WEDNESDAY...
FOR TODAY: STILL EXPECT THIS TO BECOME A MILD AND BLUSTERY DAY WITH
THE BEST RAIN CHANCES HOLDING OFF UNTIL AFTERNOON. A SOMEWHAT
COMPLEX SURFACE PATTERN IS IN PLACE WITH A DIFFUSE WEDGE FRONT
SITTING THROUGH THE NC PIEDMONT WITH A MORE SUBSTANTIAL FRONT
FARTHER SOUTH ACROSS SRN SC... AND THE STRONG COLD FRONT BACK ACROSS
CENTRAL TN. SURFACE WINDS REMAIN CALM TO LIGHT NE WITHIN THE
RESIDUAL STABLE POOL OVER THE PIEDMONT AND LIGHT FROM THE SE OVER
SRN/ERN NC. BUT WINDS ABOVE 1500 FT AGL HAVE ALREADY BEGUN TO
INCREASE AS NOTED ON AMDAR AIRCRAFT SOUNDINGS... AND THE LATEST RUC
SIMILARLY SHOWS WINDS INCREASING TO 30 KTS TOWARD DAYBREAK AROUND
1500-2000 FT. THE SURFACE BASED STABLE LAYER... HOWEVER... SHOULD
CONTINUE TO KEEP THESE STRONG WINDS UP OFF THE SURFACE THROUGH MID
MORNING... WHEN FORECAST SOUNDINGS INDICATE SUFFICIENT TURBULENT
MIXING TO SCOUR OUT THIS RESIDUAL STABLE POOL. ONCE IT DOES...
PROBABLY NOT UNTIL LATE THIS MORNING... SUSTAINED WINDS ARE LIKELY
TO APPROACH 20 KTS (23 MPH) WITH GUSTS TO 35 KTS (40 MPH) POSSIBLE.
THIS IS CLOSE TO WIND ADVISORY CRITERIA (GUSTS OVER 40 KTS/46 MPH).
BUT HISTORICALLY IT`S BEEN DIFFICULT TO REACH ADVISORY CRITERIA
WINDS IN WARM ADVECTION SITUATIONS. THEY MORE OFTEN HAVE OCCURRED
WITHIN STRONG COLD AIR ADVECTION. WILL ISSUE A SPECIAL WEATHER
STATEMENT TO HIGHLIGHT THE BLUSTERY WINDS... BUT WILL HOLD OFF ON AN
ADVISORY FOR NOW. REGARDING THE EXPECTED RAIN... THIS SYSTEM RETAINS
AN ANAFRONTAL STRUCTURE... THUS THE BULK OF THE RAINFALL IS EXPECTED
TO BE NEAR OR JUST AFTER COLD FRONTAL PASSAGE... WHICH SHOULD OCCUR
BETWEEN 2 AND 6 PM. AHEAD OF THE FRONT... AREAS OF DRIZZLE AND FOG
WILL PERSIST THROUGH DAYBREAK. ONCE WE ARE FULLY IN THE WARM
SECTOR... WITH LIMITED FORCING... ONLY PATCHY SHOWERS ARE EXPECTED
THROUGH NOON. IT SHOULD BE NOTED THAT THE LATEST NAM SHOWS THE
STABLE POOL HOLDING ON IN THE TRIAD UNTIL COLD FRONT PASSAGE... AND
THIS IS CERTAINLY POSSIBLE GIVEN THE 1000-FT-DEEP STABLE LAYER SHOWN
ON THE 00Z GSO SOUNDING. AT ANY RATE... RAIN AMOUNTS WILL BE LIGHT
THIS MORNING AND LOW CHANCE POPS WILL SUFFICE. THEN THIS
AFTERNOON... AS FORCING FOR ASCENT INCREASES AS THE UPPER JET`S
RIGHT ENTRANCE REGION APPROACHES ALONG WITH STRONG LOW LEVEL
MOISTURE TRANSPORT AND HIGH PRECIPITABLE WATER... HAVE POPS RISING
TO CATEGORICAL WEST/CHANCE EAST THROUGH MID AFTERNOON... THEN
SHIFTING TO CATEGORICAL EAST AND LOWERING POPS WEST. INSTABILITY...
ESPECIALLY WITHIN THE MIXED PHASE REGION ALOFT WHERE LIGHTNING IS
PRODUCED... STILL LOOKS VERY MINOR AND WILL LEAVE OUT THE MENTION OF
THUNDER... ALTHOUGH A STRIKE OR TWO IS POSSIBLE OVER THE SOUTHERN
COASTAL PLAIN. STORM TOTAL RAINFALL IS EXPECTED TO RANGE FROM A
THIRD TO AROUND A HALF INCH. TEMPERATURES HAVE HELD FAIRLY STEADY
EVERYWHERE OVERNIGHT... BUT ONCE THE WARM ADVECTION DEEPENS AND
INCREASES LATER THIS MORNING... READINGS SHOULD RISE INTO THE MID
60S-AROUND 70 OVER ALL BUT THE FAR NW COUNTIES... WHERE THE
POSSIBILITY OF THE LINGERING STABLE POOL IS GREAT ENOUGH TO HOLD
HIGH TEMPS TO 55-60.
FOR TONIGHT: WINDS SHOULD DIMINISH QUICKLY BEHIND THE FRONT. WILL
KEEP POPS IN THE SOUTHEAST CWA THROUGH MID EVENING UNTIL THE FRONT
PUSHES OFF THE COAST. THE NORTHWEST CWA SHOULD FEEL THE DRYING
EFFECTS OF THE DOWNSLOPE FLOW... HOWEVER THE REST OF THE AREA MAY
SEE LINGERING CLOUDS FOR MUCH OF THE NIGHT AS THE 850 MB FLOW
REMAINS FROM THE WSW THROUGH DAYBREAK THURSDAY. ALSO... WE WILL
REMAIN ON THE SE SIDE OF THE 140+ KT UPPER JET CORE... LIKELY
MEANING A PERSISTENT STREAM OF HIGH CLOUDS. HAVE RAISED SKY COVER
QUITE A BIT OVER THE SOUTHERN AND EASTERN CWA TONIGHT. THE HIGH
PRESSURE AREA BEGINS TO BUILD INTO NC FROM THE WEST... BUT THE BULK
OF THE MUCH CHILLIER AIR APPEARS TO GET HELD UP BY THE APPALACHIANS.
WILL HAVE LOWS FROM 30 TO 41 NW TO SE... CLOSE TO THE EXISTING
FORECAST. -GIH
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 255 AM WEDNESDAY...
FOR THURSDAY: WEAK HIGH PRESSURE TRIES TO BUILD IN BEHIND THE FRONT
FROM THE NW... ALTHOUGH A TRAILING LOW PRESSURE TROUGH IS LIKELY TO
SETTLE NEAR OR JUST SOUTH OF THE NC/SC STATE LINE THROUGH THURSDAY.
DESPITE INTENSE DRYING TAKING PLACE IN THE MID LEVELS... WE
ANTICIPATE RESIDUAL CLOUDINESS BELOW THE SUBSIDENCE INVERSION
ALOFT... AROUND 3000 FT AGL... THROUGH AT LEAST THURSDAY MORNING
MAINLY OVER THE SOUTHEAST HALF OF THE CWA. ALSO... WHILE THE
STRONGEST PORTIONS OF THE UPPER JET WILL BE TO OUR NE AND SW THROUGH
THURSDAY... SWRLY SPEEDS ALOFT WILL BE STRONG ENOUGH FOR WEAK
UPGLIDE AT 330 K OVER CENTRAL NC... WHICH SHOULD GENERATE SOME HIGH
CLOUDS. BUT IN GENERAL... IT SHOULD BE A QUIET WEATHER DAY WITH SOME
FILTERED SUNSHINE OVER THE NW IN THE AFTERNOON. WITH THE INFLUX OF
COLD AIR LIKELY TO BE HELD UP TO SOME DEGREE BY THE MOUNTAINS AS
NOTED ABOVE... EXPECT RATHER SEASONABLE TEMPERATURES WITH HIGHS IN
THE UPPER 40S TO LOWER 50S.
FOR THURSDAY NIGHT THROUGH FRIDAY NIGHT: WEAK HIGH PRESSURE AND VERY
LIGHT N-NE SURFACE FLOW WILL PERSIST OVER THE REGION THROUGH
THURSDAY NIGHT. A VEIL OF HIGH CLOUDS SHOULD LINGER WITH A 140 KT
JET SITTING OVERHEAD... AND AS 850 MB WINDS BACK TO THE SW...
SCATTERED STRATOCUMULS CLOUDS ARE PROBABLE TOWARD MORNING. HAVE
BUMPED LOWS UP A TAD TO 29-33... ALTHOUGH THE WEAK BOUNDARY LAYER
FLOW SHOULD ALLOW A GOOD SHALLOW INVERSION TO DEVELOP WITH NOCTURNAL
COOLING AT THE GROUND. THEN ON FRIDAY/FRIDAY NIGHT... THE MEAN
TROUGH AXIS WHICH RELOADS FROM THE GREAT LAKES THROUGH THE LOWER
MISS VALLEY THURSDAY NIGHT WILL SHIFT EASTWARD... SWINGING THROUGH
NC FRIDAY NIGHT. A SHEARED VORTICITY MAXIMUM SWINGING THROUGH THE
SOUTHEAST SIDE OF THIS TROUGH IS PROGGED BY THE NAM/GFS/ECMWF/GEM TO
SWEEP NORTHEASTWARD THROUGH CENTRAL/ERN NC FRIDAY AFTERNOON.
FORECAST SOUNDINGS SHOW NICELY STEEPENING SURFACE-750 MB LAPSE
RATES... HOWEVER THE MODELS HAVE TRENDED DRIER SINCE YESTERDAY`S
RUNS. WILL LEAVE THE FORECAST DRY. THE UPPER JET FINALLY MOVES WELL
EAST OF OUR AREA FRIDAY NIGHT AS THE UPPER TROUGH AXIS SWINGS
THROUGH... AND EXPECT MOSTLY CLEAR SKIES AND A STABLE/DRY COLUMN. WE
COULD SEE A PERIOD OF GUSTY WINDS FRIDAY EVENING INTO THE EARLY
OVERNIGHT AS THE THERMAL TROUGH PASSES THROUGH. LOW LEVEL
THICKNESSES HOLD NEAR NORMAL FRIDAY... SO EXPECT HIGHS OF 48-54.
LOWS 20-26 FRIDAY NIGHT AS THICKNESSES PLUMMET. -GIH
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 330 AM WEDNESDAY...
FOR SATURDAY THROUGH SUNDAY: THE WEEKEND SHOULD BE QUIET WITH
SHORTWAVE RIDGING ALOFT... BETWEEN THE TROUGH SHIFTING OFFSHORE AND
THE NEXT SYSTEM DROPPING THROUGH THE MIDWEST. WITH HIGH PRESSURE
OVERHEAD... WE SHOULD SEE LITTLE IN THE WAY OF CLOUDS. THICKNESSES
REBOUND NICELY FROM AROUND 35 M BELOW NORMAL SATURDAY MORNING...
HEADING BACK TO JUST ABOVE NORMAL BY LATE SUNDAY. NO MAJOR CHANGE TO
TEMPS... HIGHS 43-48 SATURDAY AND 51-56 SUNDAY.
FOR SUNDAY NIGHT-TUESDAY (UPDATED FOR 06Z MODEL DATA): MID LEVEL
TROUGHING AMPLIFIES OVER CENTRAL NOAM SUNDAY NIGHT... AND THIS
TROUGH PUSHES EASTWARD THROUGH EARLY TUESDAY... AMPLIFYING AND
TAKING ON A SLIGHTLY NEGATIVE TILT. THE 00Z GFS/ECMWF DIFFER ON
TIMING BUT BOTH SHOW A VORTEX CLOSING OFF OVER THE INTERIOR
NORTHEAST... AND THE 06Z GFS IS EVEN STRONGER... CLOSING OFF THE
VORTEX OVER VA. THE GFS/ECMWF BOTH SHOW SURFACE LOW PRESSURE
DEVELOPING OVER THE EASTERN GULF AND INTENSIFYING AS IT TRACKS UP
THROUGH NC... WITH THE 00Z AND 06Z GFS RUNS ESPECIALLY INTENSE WITH
THIS FEATURE. THE GFS/ECMWF BOTH SHOW INTENSE MOISTURE TRANSPORT
INTO THE SOUTHEAST AND CAROLINAS AHEAD OF THIS GULF LOW... AND THE
FORECAST THERMAL PROFILES HINT AT POTENTIAL WINTRY WEATHER OVER THE
WESTERN HALF OF THE STATE. WHILE IT IS FAR TOO EARLY TO MAKE A CALL
ON PRECIP TYPE OR ON THE DETAILS OF SUCH A PATTERN... WILL INCREASE
POPS UP TO LOW CHANCE MONDAY AND 30-40% CHANCE MONDAY NIGHT...
DECREASING A BIT TUESDAY DUE TO TIMING UNCERTAINTY. EXPECT HIGHS IN
THE MID-UPPER 50S MONDAY AND LOWER 50S TUESDAY... BUT THESE COULD
CHANGE QUITE A BIT IF WIDESPREAD PRECIP COMES TO PASS. -GIH
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AS OF 120 AM WEDNESDAY...
LIFR CONDITIONS IN STRATUS...DRIZZLE AND FOG WILL PERSIST THROUGH
MID TO LATE MORNING (~14/15Z) AS SOUTHWEST FLOW JUST OFF THE SURFACE
OVERRUNS COOL...MOIST NORTHEAST FLOW AT THE SURFACE. CONDITIONS WILL
LIFT TO MVFR LATE MORNING TO EARLY AFTERNOON AS A WARM FRONT PUSHES
NORTH THROUGH THE REGION. LOW LEVEL WIND SHEAR WILL BE A THREAT THIS
MORNING THROUGH EARLY AFTERNOON (ROUGHLY 08-17Z) AS THE FLOW ABOVE
15 HUNDRED FEET STRENGTHENS TO 40 TO 50 KNOTS.
A COLD FRONT WILL APPROACH AND MOVE ACROSS CENTRAL NORTH CAROLINA
BETWEEN 15Z THIS MORNING AND 00Z THURSDAY. AS THE GRADIENT TIGHTENS
SURFACE WINDS COULD GUST TO AT LEAST 35 KNOTS DURING THE AFTERNOON.
WITH THE FRONTAL PASSAGE WILL ALSO COME THE THREAT OF MVFR CEILINGS
IN RAIN.
SOUNDING DATA SHOW RAPID DRYING BEHIND THE FRONT AS HIGH PRESSURE
BUILDS IN NORTH CAROLINA FROM THE WEST... THEREFORE WE CAN EXPECT A
CLEARING TREND IN THE WEST AFTER 00Z TONIGHT... SPREADING TO THE
EAST BY 09Z THURSDAY MORNING.
HIGH PRESSURE WILL CONTROL THE AREAS WEATHER THROUGH SUNDAY...
HOWEVER AN UPPER TROUGH MOVING ACROSS THE REGION FRIDAY THROUGH
EARLY SATURDAY MAY HAVE ENOUGH MOISTURE WITH IT TO ENHANCE THE
DEVELOPMENT OF CLOUDS BETWEEN 35 HUNDRED AND 5 THOUSAND FEET.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR
NCZ026>028-041>043-073>078-083>086-088-089.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...HARTFIELD
AVIATION...RHJ
AREA FORECAST DISCUSSION
NWS RALEIGH NC
345 AM EST WED JAN 28 2009
.SYNOPSIS...
A WARM FRONT WILL SLOWLY MOVE NORTH ACROSS THE REGION THROUGH THIS
MORNING... THEN BLUSTERY SOUTHWEST FLOW WILL BRING MILDER
TEMPERATURES FOR TODAY. A COLD FRONT WILL MOVE SOUTHEAST THROUGH THE
AREA THIS AFTERNOON INTO EARLY EVENING... BRINGING WIDESPREAD
SHOWERS. BEHIND THE FRONT... DRIER AND COOLER CONDITIONS WILL FOLLOW
ON THURSDAY THROUGH FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 AM WEDNESDAY...
FOR TODAY: STILL EXPECT THIS TO BECOME A MILD AND BLUSTERY DAY WITH
THE BEST RAIN CHANCES HOLDING OFF UNTIL AFTERNOON. A SOMEWHAT
COMPLEX SURFACE PATTERN IS IN PLACE WITH A DIFFUSE WEDGE FRONT
SITTING THROUGH THE NC PIEDMONT WITH A MORE SUBSTANTIAL FRONT
FARTHER SOUTH ACROSS SRN SC... AND THE STRONG COLD FRONT BACK ACROSS
CENTRAL TN. SURFACE WINDS REMAIN CALM TO LIGHT NE WITHIN THE
RESIDUAL STABLE POOL OVER THE PIEDMONT AND LIGHT FROM THE SE OVER
SRN/ERN NC. BUT WINDS ABOVE 1500 FT AGL HAVE ALREADY BEGUN TO
INCREASE AS NOTED ON AMDAR AIRCRAFT SOUNDINGS... AND THE LATEST RUC
SIMILARLY SHOWS WINDS INCREASING TO 30 KTS TOWARD DAYBREAK AROUND
1500-2000 FT. THE SURFACE BASED STABLE LAYER... HOWEVER... SHOULD
CONTINUE TO KEEP THESE STRONG WINDS UP OFF THE SURFACE THROUGH MID
MORNING... WHEN FORECAST SOUNDINGS INDICATE SUFFICIENT TURBULENT
MIXING TO SCOUR OUT THIS RESIDUAL STABLE POOL. ONCE IT DOES...
PROBABLY NOT UNTIL LATE THIS MORNING... SUSTAINED WINDS ARE LIKELY
TO APPROACH 20 KTS (23 MPH) WITH GUSTS TO 35 KTS (40 MPH) POSSIBLE.
THIS IS CLOSE TO WIND ADVISORY CRITERIA (GUSTS OVER 40 KTS/46 MPH).
BUT HISTORICALLY IT`S BEEN DIFFICULT TO REACH ADVISORY CRITERIA
WINDS IN WARM ADVECTION SITUATIONS. THEY MORE OFTEN HAVE OCCURRED
WITHIN STRONG COLD AIR ADVECTION. WILL ISSUE A SPECIAL WEATHER
STATEMENT TO HIGHLIGHT THE BLUSTERY WINDS... BUT WILL HOLD OFF ON AN
ADVISORY FOR NOW. REGARDING THE EXPECTED RAIN... THIS SYSTEM RETAINS
AN ANAFRONTAL STRUCTURE... THUS THE BULK OF THE RAINFALL IS EXPECTED
TO BE NEAR OR JUST AFTER COLD FRONTAL PASSAGE... WHICH SHOULD OCCUR
BETWEEN 2 AND 6 PM. AHEAD OF THE FRONT... AREAS OF DRIZZLE AND FOG
WILL PERSIST THROUGH DAYBREAK. ONCE WE ARE FULLY IN THE WARM
SECTOR... WITH LIMITED FORCING... ONLY PATCHY SHOWERS ARE EXPECTED
THROUGH NOON. IT SHOULD BE NOTED THAT THE LATEST NAM SHOWS THE
STABLE POOL HOLDING ON IN THE TRIAD UNTIL COLD FRONT PASSAGE... AND
THIS IS CERTAINLY POSSIBLE GIVEN THE 1000-FT-DEEP STABLE LAYER SHOWN
ON THE 00Z GSO SOUNDING. AT ANY RATE... RAIN AMOUNTS WILL BE LIGHT
THIS MORNING AND LOW CHANCE POPS WILL SUFFICE. THEN THIS
AFTERNOON... AS FORCING FOR ASCENT INCREASES AS THE UPPER JET`S
RIGHT ENTRANCE REGION APPROACHES ALONG WITH STRONG LOW LEVEL
MOISTURE TRANSPORT AND HIGH PRECIPITABLE WATER... HAVE POPS RISING
TO CATEGORICAL WEST/CHANCE EAST THROUGH MID AFTERNOON... THEN
SHIFTING TO CATEGORICAL EAST AND LOWERING POPS WEST. INSTABILITY...
ESPECIALLY WITHIN THE MIXED PHASE REGION ALOFT WHERE LIGHTNING IS
PRODUCED... STILL LOOKS VERY MINOR AND WILL LEAVE OUT THE MENTION OF
THUNDER... ALTHOUGH A STRIKE OR TWO IS POSSIBLE OVER THE SOUTHERN
COASTAL PLAIN. STORM TOTAL RAINFALL IS EXPECTED TO RANGE FROM A
THIRD TO AROUND A HALF INCH. TEMPERATURES HAVE HELD FAIRLY STEADY
EVERYWHERE OVERNIGHT... BUT ONCE THE WARM ADVECTION DEEPENS AND
INCREASES LATER THIS MORNING... READINGS SHOULD RISE INTO THE MID
60S-AROUND 70 OVER ALL BUT THE FAR NW COUNTIES... WHERE THE
POSSIBILITY OF THE LINGERING STABLE POOL IS GREAT ENOUGH TO HOLD
HIGH TEMPS TO 55-60.
FOR TONIGHT: WINDS SHOULD DIMINISH QUICKLY BEHIND THE FRONT. WILL
KEEP POPS IN THE SOUTHEAST CWA THROUGH MID EVENING UNTIL THE FRONT
PUSHES OFF THE COAST. THE NORTHWEST CWA SHOULD FEEL THE DRYING
EFFECTS OF THE DOWNSLOPE FLOW... HOWEVER THE REST OF THE AREA MAY
SEE LINGERING CLOUDS FOR MUCH OF THE NIGHT AS THE 850 MB FLOW
REMAINS FROM THE WSW THROUGH DAYBREAK THURSDAY. ALSO... WE WILL
REMAIN ON THE SE SIDE OF THE 140+ KT UPPER JET CORE... LIKELY
MEANING A PERSISTENT STREAM OF HIGH CLOUDS. HAVE RAISED SKY COVER
QUITE A BIT OVER THE SOUTHERN AND EASTERN CWA TONIGHT. THE HIGH
PRESSURE AREA BEGINS TO BUILD INTO NC FROM THE WEST... BUT THE BULK
OF THE MUCH CHILLIER AIR APPEARS TO GET HELD UP BY THE APPALACHIANS.
WILL HAVE LOWS FROM 30 TO 41 NW TO SE... CLOSE TO THE EXISTING
FORECAST. -GIH
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 255 AM WEDNESDAY...
FOR THURSDAY: WEAK HIGH PRESSURE TRIES TO BUILD IN BEHIND THE FRONT
FROM THE NW... ALTHOUGH A TRAILING LOW PRESSURE TROUGH IS LIKELY TO
SETTLE NEAR OR JUST SOUTH OF THE NC/SC STATE LINE THROUGH THURSDAY.
DESPITE INTENSE DRYING TAKING PLACE IN THE MID LEVELS... WE
ANTICIPATE RESIDUAL CLOUDINESS BELOW THE SUBSIDENCE INVERSION
ALOFT... AROUND 3000 FT AGL... THROUGH AT LEAST THURSDAY MORNING
MAINLY OVER THE SOUTHEAST HALF OF THE CWA. ALSO... WHILE THE
STRONGEST PORTIONS OF THE UPPER JET WILL BE TO OUR NE AND SW THROUGH
THURSDAY... SWRLY SPEEDS ALOFT WILL BE STRONG ENOUGH FOR WEAK
UPGLIDE AT 330 K OVER CENTRAL NC... WHICH SHOULD GENERATE SOME HIGH
CLOUDS. BUT IN GENERAL... IT SHOULD BE A QUIET WEATHER DAY WITH SOME
FILTERED SUNSHINE OVER THE NW IN THE AFTERNOON. WITH THE INFLUX OF
COLD AIR LIKELY TO BE HELD UP TO SOME DEGREE BY THE MOUNTAINS AS
NOTED ABOVE... EXPECT RATHER SEASONABLE TEMPERATURES WITH HIGHS IN
THE UPPER 40S TO LOWER 50S.
FOR THURSDAY NIGHT THROUGH FRIDAY NIGHT: WEAK HIGH PRESSURE AND VERY
LIGHT N-NE SURFACE FLOW WILL PERSIST OVER THE REGION THROUGH
THURSDAY NIGHT. A VEIL OF HIGH CLOUDS SHOULD LINGER WITH A 140 KT
JET SITTING OVERHEAD... AND AS 850 MB WINDS BACK TO THE SW...
SCATTERED STRATOCUMULS CLOUDS ARE PROBABLE TOWARD MORNING. HAVE
BUMPED LOWS UP A TAD TO 29-33... ALTHOUGH THE WEAK BOUNDARY LAYER
FLOW SHOULD ALLOW A GOOD SHALLOW INVERSION TO DEVELOP WITH NOCTURNAL
COOLING AT THE GROUND. THEN ON FRIDAY/FRIDAY NIGHT... THE MEAN
TROUGH AXIS WHICH RELOADS FROM THE GREAT LAKES THROUGH THE LOWER
MISS VALLEY THURSDAY NIGHT WILL SHIFT EASTWARD... SWINGING THROUGH
NC FRIDAY NIGHT. A SHEARED VORTICITY MAXIMUM SWINGING THROUGH THE
SOUTHEAST SIDE OF THIS TROUGH IS PROGGED BY THE NAM/GFS/ECMWF/GEM TO
SWEEP NORTHEASTWARD THROUGH CENTRAL/ERN NC FRIDAY AFTERNOON.
FORECAST SOUNDINGS SHOW NICELY STEEPENING SURFACE-750 MB LAPSE
RATES... HOWEVER THE MODELS HAVE TRENDED DRIER SINCE YESTERDAY`S
RUNS. WILL LEAVE THE FORECAST DRY. THE UPPER JET FINALLY MOVES WELL
EAST OF OUR AREA FRIDAY NIGHT AS THE UPPER TROUGH AXIS SWINGS
THROUGH... AND EXPECT MOSTLY CLEAR SKIES AND A STABLE/DRY COLUMN. WE
COULD SEE A PERIOD OF GUSTY WINDS FRIDAY EVENING INTO THE EARLY
OVERNIGHT AS THE THERMAL TROUGH PASSES THROUGH. LOW LEVEL
THICKNESSES HOLD NEAR NORMAL FRIDAY... SO EXPECT HIGHS OF 48-54.
LOWS 20-26 FRIDAY NIGHT AS THICKNESSES PLUMMET. -GIH
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 330 AM WEDNESDAY...
FOR SATURDAY THROUGH SUNDAY: THE WEEKEND SHOULD BE QUIET WITH
SHORTWAVE RIDGING ALOFT... BETWEEN THE TROUGH SHIFTING OFFSHORE AND
THE NEXT SYSTEM DROPPING THROUGH THE MIDWEST. WITH HIGH PRESSURE
OVERHEAD... WE SHOULD SEE LITTLE IN THE WAY OF CLOUDS. THICKNESSES
REBOUND NICELY FROM AROUND 35 M BELOW NORMAL SATURDAY MORNING...
HEADING BACK TO JUST ABOVE NORMAL BY LATE SUNDAY. NO MAJOR CHANGE TO
TEMPS... HIGHS 43-48 SATURDAY AND 51-56 SUNDAY.
FOR SUNDAY NIGHT-TUESDAY: MID LEVEL TROUGHING AMPLIFIES OVER CENTRAL
NOAM SUNDAY NIGHT... AND THIS TROUGH PUSHES EASTWARD AND THROUGH THE
EASTERN SEABOARD BY LATE TUESDAY WITH AN ATTENDANT SURFACE COLD
FRONT. THE GFS/ECMWF SHOW INTENSE MOISTURE TRANSPORT INTO THE
SOUTHEAST AND CAROLINAS AHEAD OF THE FRONT... ALONG WITH LOW
PRESSURE COMING OUT OF THE EASTERN GULF UP THROUGH NC. WILL INCREASE
POPS UP TO LOW CHANCE MONDAY AND 30-40% CHANCE MONDAY NIGHT...
DECREASING A BIT TUESDAY DUE TO TIMING UNCERTAINTY. EXPECT HIGHS IN
THE MID-UPPER 50S MONDAY AND LOWER 50S TUESDAY. -GIH
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AS OF 120 AM WEDNESDAY...
LIFR CONDITIONS IN STRATUS...DRIZZLE AND FOG WILL PERSIST THROUGH
MID TO LATE MORNING (~14/15Z) AS SOUTHWEST FLOW JUST OFF THE SURFACE
OVERRUNS COOL...MOIST NORTHEAST FLOW AT THE SURFACE. CONDITIONS WILL
LIFT TO MVFR LATE MORNING TO EARLY AFTERNOON AS A WARM FRONT PUSHES
NORTH THROUGH THE REGION. LOW LEVEL WIND SHEAR WILL BE A THREAT THIS
MORNING THROUGH EARLY AFTERNOON (ROUGHLY 08-17Z) AS THE FLOW ABOVE
15 HUNDRED FEET STRENGTHENS TO 40 TO 50 KNOTS.
A COLD FRONT WILL APPROACH AND MOVE ACROSS CENTRAL NORTH CAROLINA
BETWEEN 15Z THIS MORNING AND 00Z THURSDAY. AS THE GRADIENT TIGHTENS
SURFACE WINDS COULD GUST TO AT LEAST 35 KNOTS DURING THE AFTERNOON.
WITH THE FRONTAL PASSAGE WILL ALSO COME THE THREAT OF MVFR CEILINGS
IN RAIN.
SOUNDING DATA SHOW RAPID DRYING BEHIND THE FRONT AS HIGH PRESSURE
BUILDS IN NORTH CAROLINA FROM THE WEST... THEREFORE WE CAN EXPECT A
CLEARING TREND IN THE WEST AFTER 00Z TONIGHT... SPREADING TO THE
EAST BY 09Z THURSDAY MORNING.
HIGH PRESSURE WILL CONTROL THE AREAS WEATHER THROUGH SUNDAY...
HOWEVER AN UPPER TROUGH MOVING ACROSS THE REGION FRIDAY THROUGH
EARLY SATURDAY MAY HAVE ENOUGH MOISTURE WITH IT TO ENHANCE THE
DEVELOPMENT OF CLOUDS BETWEEN 35 HUNDRED AND 5 THOUSAND FEET.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...HARTFIELD
AVIATION...RHJ
AREA FORECAST DISCUSSION
NWS RALEIGH NC
255 AM EST WED JAN 28 2009
.SYNOPSIS...
A WARM FRONT WILL SLOWLY MOVE NORTH ACROSS THE REGION THROUGH THIS
MORNING... THEN BLUSTERY SOUTHWEST FLOW WILL BRING MILDER
TEMPERATURES FOR TODAY. A COLD FRONT WILL MOVE SOUTHEAST THROUGH THE
AREA THIS AFTERNOON INTO EARLY EVENING... BRINGING WIDESPREAD
SHOWERS. BEHIND THE FRONT... DRIER AND COOLER CONDITIONS WILL FOLLOW
ON THURSDAY THROUGH FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 AM WEDNESDAY...
FOR TODAY: STILL EXPECT THIS TO BECOME A MILD AND BLUSTERY DAY WITH
THE BEST RAIN CHANCES HOLDING OFF UNTIL AFTERNOON. A SOMEWHAT
COMPLEX SURFACE PATTERN IS IN PLACE WITH A DIFFUSE WEDGE FRONT
SITTING THROUGH THE NC PIEDMONT WITH A MORE SUBSTANTIAL FRONT
FARTHER SOUTH ACROSS SRN SC... AND THE STRONG COLD FRONT BACK ACROSS
CENTRAL TN. SURFACE WINDS REMAIN CALM TO LIGHT NE WITHIN THE
RESIDUAL STABLE POOL OVER THE PIEDMONT AND LIGHT FROM THE SE OVER
SRN/ERN NC. BUT WINDS ABOVE 1500 FT AGL HAVE ALREADY BEGUN TO
INCREASE AS NOTED ON AMDAR AIRCRAFT SOUNDINGS... AND THE LATEST RUC
SIMILARLY SHOWS WINDS INCREASING TO 30 KTS TOWARD DAYBREAK AROUND
1500-2000 FT. THE SURFACE BASED STABLE LAYER... HOWEVER... SHOULD
CONTINUE TO KEEP THESE STRONG WINDS UP OFF THE SURFACE THROUGH MID
MORNING... WHEN FORECAST SOUNDINGS INDICATE SUFFICIENT TURBULENT
MIXING TO SCOUR OUT THIS RESIDUAL STABLE POOL. ONCE IT DOES...
PROBABLY NOT UNTIL LATE THIS MORNING... SUSTAINED WINDS ARE LIKELY
TO APPROACH 20 KTS (23 MPH) WITH GUSTS TO 35 KTS (40 MPH) POSSIBLE.
THIS IS CLOSE TO WIND ADVISORY CRITERIA (GUSTS OVER 40 KTS/46 MPH).
BUT HISTORICALLY IT`S BEEN DIFFICULT TO REACH ADVISORY CRITERIA
WINDS IN WARM ADVECTION SITUATIONS. THEY MORE OFTEN HAVE OCCURRED
WITHIN STRONG COLD AIR ADVECTION. WILL ISSUE A SPECIAL WEATHER
STATEMENT TO HIGHLIGHT THE BLUSTERY WINDS... BUT WILL HOLD OFF ON AN
ADVISORY FOR NOW. REGARDING THE EXPECTED RAIN... THIS SYSTEM RETAINS
AN ANAFRONTAL STRUCTURE... THUS THE BULK OF THE RAINFALL IS EXPECTED
TO BE NEAR OR JUST AFTER COLD FRONTAL PASSAGE... WHICH SHOULD OCCUR
BETWEEN 2 AND 6 PM. AHEAD OF THE FRONT... AREAS OF DRIZZLE AND FOG
WILL PERSIST THROUGH DAYBREAK. ONCE WE ARE FULLY IN THE WARM
SECTOR... WITH LIMITED FORCING... ONLY PATCHY SHOWERS ARE EXPECTED
THROUGH NOON. IT SHOULD BE NOTED THAT THE LATEST NAM SHOWS THE
STABLE POOL HOLDING ON IN THE TRIAD UNTIL COLD FRONT PASSAGE... AND
THIS IS CERTAINLY POSSIBLE GIVEN THE 1000-FT-DEEP STABLE LAYER SHOWN
ON THE 00Z GSO SOUNDING. AT ANY RATE... RAIN AMOUNTS WILL BE LIGHT
THIS MORNING AND LOW CHANCE POPS WILL SUFFICE. THEN THIS
AFTERNOON... AS FORCING FOR ASCENT INCREASES AS THE UPPER JET`S
RIGHT ENTRANCE REGION APPROACHES ALONG WITH STRONG LOW LEVEL
MOISTURE TRANSPORT AND HIGH PRECIPITABLE WATER... HAVE POPS RISING
TO CATEGORICAL WEST/CHANCE EAST THROUGH MID AFTERNOON... THEN
SHIFTING TO CATEGORICAL EAST AND LOWERING POPS WEST. INSTABILITY...
ESPECIALLY WITHIN THE MIXED PHASE REGION ALOFT WHERE LIGHTNING IS
PRODUCED... STILL LOOKS VERY MINOR AND WILL LEAVE OUT THE MENTION OF
THUNDER... ALTHOUGH A STRIKE OR TWO IS POSSIBLE OVER THE SOUTHERN
COASTAL PLAIN. STORM TOTAL RAINFALL IS EXPECTED TO RANGE FROM A
THIRD TO AROUND A HALF INCH. TEMPERATURES HAVE HELD FAIRLY STEADY
EVERYWHERE OVERNIGHT... BUT ONCE THE WARM ADVECTION DEEPENS AND
INCREASES LATER THIS MORNING... READINGS SHOULD RISE INTO THE MID
60S-AROUND 70 OVER ALL BUT THE FAR NW COUNTIES... WHERE THE
POSSIBILITY OF THE LINGERING STABLE POOL IS GREAT ENOUGH TO HOLD
HIGH TEMPS TO 55-60.
FOR TONIGHT: WINDS SHOULD DIMINISH QUICKLY BEHIND THE FRONT. WILL
KEEP POPS IN THE SOUTHEAST CWA THROUGH MID EVENING UNTIL THE FRONT
PUSHES OFF THE COAST. THE NORTHWEST CWA SHOULD FEEL THE DRYING
EFFECTS OF THE DOWNSLOPE FLOW... HOWEVER THE REST OF THE AREA MAY
SEE LINGERING CLOUDS FOR MUCH OF THE NIGHT AS THE 850 MB FLOW
REMAINS FROM THE WSW THROUGH DAYBREAK THURSDAY. ALSO... WE WILL
REMAIN ON THE SE SIDE OF THE 140+ KT UPPER JET CORE... LIKELY
MEANING A PERSISTENT STREAM OF HIGH CLOUDS. HAVE RAISED SKY COVER
QUITE A BIT OVER THE SOUTHERN AND EASTERN CWA TONIGHT. THE HIGH
PRESSURE AREA BEGINS TO BUILD INTO NC FROM THE WEST... BUT THE BULK
OF THE MUCH CHILLIER AIR APPEARS TO GET HELD UP BY THE APPALACHIANS.
WILL HAVE LOWS FROM 30 TO 41 NW TO SE... CLOSE TO THE EXISTING
FORECAST. -GIH
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 255 AM WEDNESDAY...
FOR THURSDAY: WEAK HIGH PRESSURE TRIES TO BUILD IN BEHIND THE FRONT
FROM THE NW... ALTHOUGH A TRAILING LOW PRESSURE TROUGH IS LIKELY TO
SETTLE NEAR OR JUST SOUTH OF THE NC/SC STATE LINE THROUGH THURSDAY.
DESPITE INTENSE DRYING TAKING PLACE IN THE MID LEVELS... WE
ANTICIPATE RESIDUAL CLOUDINESS BELOW THE SUBSIDENCE INVERSION
ALOFT... AROUND 3000 FT AGL... THROUGH AT LEAST THURSDAY MORNING
MAINLY OVER THE SOUTHEAST HALF OF THE CWA. ALSO... WHILE THE
STRONGEST PORTIONS OF THE UPPER JET WILL BE TO OUR NE AND SW THROUGH
THURSDAY... SWRLY SPEEDS ALOFT WILL BE STRONG ENOUGH FOR WEAK
UPGLIDE AT 330 K OVER CENTRAL NC... WHICH SHOULD GENERATE SOME HIGH
CLOUDS. BUT IN GENERAL... IT SHOULD BE A QUIET WEATHER DAY WITH SOME
FILTERED SUNSHINE OVER THE NW IN THE AFTERNOON. WITH THE INFLUX OF
COLD AIR LIKELY TO BE HELD UP TO SOME DEGREE BY THE MOUNTAINS AS
NOTED ABOVE... EXPECT RATHER SEASONABLE TEMPERATURES WITH HIGHS IN
THE UPPER 40S TO LOWER 50S.
FOR THURSDAY NIGHT THROUGH FRIDAY NIGHT: WEAK HIGH PRESSURE AND VERY
LIGHT N-NE SURFACE FLOW WILL PERSIST OVER THE REGION THROUGH
THURSDAY NIGHT. A VEIL OF HIGH CLOUDS SHOULD LINGER WITH A 140 KT
JET SITTING OVERHEAD... AND AS 850 MB WINDS BACK TO THE SW...
SCATTERED STRATOCUMULS CLOUDS ARE PROBABLE TOWARD MORNING. HAVE
BUMPED LOWS UP A TAD TO 29-33... ALTHOUGH THE WEAK BOUNDARY LAYER
FLOW SHOULD ALLOW A GOOD SHALLOW INVERSION TO DEVELOP WITH NOCTURNAL
COOLING AT THE GROUND. THEN ON FRIDAY/FRIDAY NIGHT... THE MEAN
TROUGH AXIS WHICH RELOADS FROM THE GREAT LAKES THROUGH THE LOWER
MISS VALLEY THURSDAY NIGHT WILL SHIFT EASTWARD... SWINGING THROUGH
NC FRIDAY NIGHT. A SHEARED VORTICITY MAXIMUM SWINGING THROUGH THE
SOUTHEAST SIDE OF THIS TROUGH IS PROGGED BY THE NAM/GFS/ECMWF/GEM TO
SWEEP NORTHEASTWARD THROUGH CENTRAL/ERN NC FRIDAY AFTERNOON.
FORECAST SOUNDINGS SHOW NICELY STEEPENING SURFACE-750 MB LAPSE
RATES... HOWEVER THE MODELS HAVE TRENDED DRIER SINCE YESTERDAY`S
RUNS. WILL LEAVE THE FORECAST DRY. THE UPPER JET FINALLY MOVES WELL
EAST OF OUR AREA FRIDAY NIGHT AS THE UPPER TROUGH AXIS SWINGS
THROUGH... AND EXPECT MOSTLY CLEAR SKIES AND A STABLE/DRY COLUMN. WE
COULD SEE A PERIOD OF GUSTY WINDS FRIDAY EVENING INTO THE EARLY
OVERNIGHT AS THE THERMAL TROUGH PASSES THROUGH. LOW LEVEL
THICKNESSES HOLD NEAR NORMAL FRIDAY... SO EXPECT HIGHS OF 48-54.
LOWS 20-26 FRIDAY NIGHT AS THICKNESSES PLUMMET. -GIH
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 300 PM TUESDAY...
SURFACE HIGH PRESSURE BUILDS INTO THE STATE FROM THE WEST...
CENTERING OVER THE CAROLINAS SATURDAY NIGHT.
MODELS IN ROUGH AGREEMENT ON ANOTHER UPPER TROUGH DROPPING INTO
TENNESSEE MONDAY EVENING... WITH A DEVELOPING NORTH GULF COAST LOW
RISING NORTHEAST TOWARD THE CAROLINAS. GFS MODEL HAS A TENDENCY TO
OVERINTENSIFY THESE SYSTEMS SO TEMPERING THAT MODELS EXPECTATIONS.
HOWEVER TEMPERATURES ARE CLOSE TO FREEZING SUNRISE TUESDAY. WITH MID
LEVELS DRYING... A FEW SNOW FLAKES COULD END THE EVENT... BUT MORE
LIKELY SOME LIGHT FREEZING RAIN... MAINLY NORTHWEST. AT SEVEN DAYS
OUT... WITH IS WILD SPECULATION AND WILL TREAT IT AS SUCH AND KEEP
FORECAST ALL RAIN.
AFTERNOON HIGHS 45 TO 55 FRIDAY THEN 40S SATURDAY...LOW TO MID 50S
AFTER THAT. LOW TEMPERATURES NEAR FREEZING THURSDAY NIGHT THEN 20 TO
25 FRIDAY NIGHT. THEN A WARMING TREND TO UPPER 20S SATURDAY NIGHT...
NEAR FREEZING SUNDAY NIGHT...LOW TO MID 30S MONDAY NIGHT.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AS OF 120 AM WEDNESDAY...
LIFR CONDITIONS IN STRATUS...DRIZZLE AND FOG WILL PERSIST THROUGH
MID TO LATE MORNING (~14/15Z) AS SOUTHWEST FLOW JUST OFF THE SURFACE
OVERRUNS COOL...MOIST NORTHEAST FLOW AT THE SURFACE. CONDITIONS WILL
LIFT TO MVFR LATE MORNING TO EARLY AFTERNOON AS A WARM FRONT PUSHES
NORTH THROUGH THE REGION. LOW LEVEL WIND SHEAR WILL BE A THREAT THIS
MORNING THROUGH EARLY AFTERNOON (ROUGHLY 08-17Z) AS THE FLOW ABOVE
15 HUNDRED FEET STRENGTHENS TO 40 TO 50 KNOTS.
A COLD FRONT WILL APPROACH AND MOVE ACROSS CENTRAL NORTH CAROLINA
BETWEEN 15Z THIS MORNING AND 00Z THURSDAY. AS THE GRADIENT TIGHTENS
SURFACE WINDS COULD GUST TO AT LEAST 35 KNOTS DURING THE AFTERNOON.
WITH THE FRONTAL PASSAGE WILL ALSO COME THE THREAT OF MVFR CEILINGS
IN RAIN.
SOUNDING DATA SHOW RAPID DRYING BEHIND THE FRONT AS HIGH PRESSURE
BUILDS IN NORTH CAROLINA FROM THE WEST... THEREFORE WE CAN EXPECT A
CLEARING TREND IN THE WEST AFTER 00Z TONIGHT... SPREADING TO THE
EAST BY 09Z THURSDAY MORNING.
HIGH PRESSURE WILL CONTROL THE AREAS WEATHER THROUGH SUNDAY...
HOWEVER AN UPPER TROUGH MOVING ACROSS THE REGION FRIDAY THROUGH
EARLY SATURDAY MAY HAVE ENOUGH MOISTURE WITH IT TO ENHANCE THE
DEVELOPMENT OF CLOUDS BETWEEN 35 HUNDRED AND 5 THOUSAND FEET.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...HARTFIELD
LONG TERM...RLH
AVIATION...RHJ
AREA FORECAST DISCUSSION
NWS RALEIGH NC
230 AM EST WED JAN 28 2009
.SYNOPSIS...
A WARM FRONT WILL SLOWLY MOVE NORTH ACROSS THE REGION THROUGH THIS
MORNING... THEN BLUSTERY SOUTHWEST FLOW WILL BRING MILDER
TEMPERATURES FOR TODAY. A COLD FRONT WILL MOVE SOUTHEAST THROUGH THE
AREA THIS AFTERNOON INTO EARLY EVENING... BRINGING WIDESPREAD
SHOWERS. BEHIND THE FRONT... DRIER AND COOLER CONDITIONS WILL FOLLOW
ON THURSDAY THROUGH FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 AM WEDNESDAY...
FOR TODAY: STILL EXPECT THIS TO BECOME A MILD AND BLUSTERY DAY WITH
THE BEST RAIN CHANCES HOLDING OFF UNTIL AFTERNOON. A SOMEWHAT
COMPLEX SURFACE PATTERN IS IN PLACE WITH A DIFFUSE WEDGE FRONT
SITTING THROUGH THE NC PIEDMONT WITH A MORE SUBSTANTIAL FRONT
FARTHER SOUTH ACROSS SRN SC... AND THE STRONG COLD FRONT BACK ACROSS
CENTRAL TN. SURFACE WINDS REMAIN CALM TO LIGHT NE WITHIN THE
RESIDUAL STABLE POOL OVER THE PIEDMONT AND LIGHT FROM THE SE OVER
SRN/ERN NC. BUT WINDS ABOVE 1500 FT AGL HAVE ALREADY BEGUN TO
INCREASE AS NOTED ON AMDAR AIRCRAFT SOUNDINGS... AND THE LATEST RUC
SIMILARLY SHOWS WINDS INCREASING TO 30 KTS TOWARD DAYBREAK AROUND
1500-2000 FT. THE SURFACE BASED STABLE LAYER... HOWEVER... SHOULD
CONTINUE TO KEEP THESE STRONG WINDS UP OFF THE SURFACE THROUGH MID
MORNING... WHEN FORECAST SOUNDINGS INDICATE SUFFICIENT TURBULENT
MIXING TO SCOUR OUT THIS RESIDUAL STABLE POOL. ONCE IT DOES...
PROBABLY NOT UNTIL LATE THIS MORNING... SUSTAINED WINDS ARE LIKELY
TO APPROACH 20 KTS (23 MPH) WITH GUSTS TO 35 KTS (40 MPH) POSSIBLE.
THIS IS CLOSE TO WIND ADVISORY CRITERIA (GUSTS OVER 40 KTS/46 MPH).
BUT HISTORICALLY IT`S BEEN DIFFICULT TO REACH ADVISORY CRITERIA
WINDS IN WARM ADVECTION SITUATIONS. THEY MORE OFTEN HAVE OCCURRED
WITHIN STRONG COLD AIR ADVECTION. WILL ISSUE A SPECIAL WEATHER
STATEMENT TO HIGHLIGHT THE BLUSTERY WINDS... BUT WILL HOLD OFF ON AN
ADVISORY FOR NOW. REGARDING THE EXPECTED RAIN... THIS SYSTEM RETAINS
AN ANAFRONTAL STRUCTURE... THUS THE BULK OF THE RAINFALL IS EXPECTED
TO BE NEAR OR JUST AFTER COLD FRONTAL PASSAGE... WHICH SHOULD OCCUR
BETWEEN 2 AND 6 PM. AHEAD OF THE FRONT... AREAS OF DRIZZLE AND FOG
WILL PERSIST THROUGH DAYBREAK. ONCE WE ARE FULLY IN THE WARM
SECTOR... WITH LIMITED FORCING... ONLY PATCHY SHOWERS ARE EXPECTED
THROUGH NOON. IT SHOULD BE NOTED THAT THE LATEST NAM SHOWS THE
STABLE POOL HOLDING ON IN THE TRIAD UNTIL COLD FRONT PASSAGE... AND
THIS IS CERTAINLY POSSIBLE GIVEN THE 1000-FT-DEEP STABLE LAYER SHOWN
ON THE 00Z GSO SOUNDING. AT ANY RATE... RAIN AMOUNTS WILL BE LIGHT
THIS MORNING AND LOW CHANCE POPS WILL SUFFICE. THEN THIS
AFTERNOON... AS FORCING FOR ASCENT INCREASES AS THE UPPER JET`S
RIGHT ENTRANCE REGION APPROACHES ALONG WITH STRONG LOW LEVEL
MOISTURE TRANSPORT AND HIGH PRECIPITABLE WATER... HAVE POPS RISING
TO CATEGORICAL WEST/CHANCE EAST THROUGH MID AFTERNOON... THEN
SHIFTING TO CATEGORICAL EAST AND LOWERING POPS WEST. INSTABILITY...
ESPECIALLY WITHIN THE MIXED PHASE REGION ALOFT WHERE LIGHTNING IS
PRODUCED... STILL LOOKS VERY MINOR AND WILL LEAVE OUT THE MENTION OF
THUNDER... ALTHOUGH A STRIKE OR TWO IS POSSIBLE OVER THE SOUTHERN
COASTAL PLAIN. STORM TOTAL RAINFALL IS EXPECTED TO RANGE FROM A
THIRD TO AROUND A HALF INCH. TEMPERATURES HAVE HELD FAIRLY STEADY
EVERYWHERE OVERNIGHT... BUT ONCE THE WARM ADVECTION DEEPENS AND
INCREASES LATER THIS MORNING... READINGS SHOULD RISE INTO THE MID
60S-AROUND 70 OVER ALL BUT THE FAR NW COUNTIES... WHERE THE
POSSIBILITY OF THE LINGERING STABLE POOL IS GREAT ENOUGH TO HOLD
HIGH TEMPS TO 55-60.
FOR TONIGHT: WINDS SHOULD DIMINISH QUICKLY BEHIND THE FRONT. WILL
KEEP POPS IN THE SOUTHEAST CWA THROUGH MID EVENING UNTIL THE FRONT
PUSHES OFF THE COAST. THE NORTHWEST CWA SHOULD FEEL THE DRYING
EFFECTS OF THE DOWNSLOPE FLOW... HOWEVER THE REST OF THE AREA MAY
SEE LINGERING CLOUDS FOR MUCH OF THE NIGHT AS THE 850 MB FLOW
REMAINS FROM THE WSW THROUGH DAYBREAK THURSDAY. ALSO... WE WILL
REMAIN ON THE SE SIDE OF THE 140+ KT UPPER JET CORE... LIKELY
MEANING A PERSISTENT STREAM OF HIGH CLOUDS. HAVE RAISED SKY COVER
QUITE A BIT OVER THE SOUTHERN AND EASTERN CWA TONIGHT. THE HIGH
PRESSURE AREA BEGINS TO BUILD INTO NC FROM THE WEST... BUT THE BULK
OF THE MUCH CHILLIER AIR APPEARS TO GET HELD UP BY THE APPALACHIANS.
WILL HAVE LOWS FROM 30 TO 41 NW TO SE... CLOSE TO THE EXISTING
FORECAST. -GIH
&&
.SHORT TERM /THURSDAY/...
AS OF 245 PM TUESDAY...
THURSDAY: RELATIVELY BENIGN WEATHER DAY ON TAP THU AS SFC HIGH
PRESSURE BUILDS IN BEHIND THE COLD FRONTAL PASSAGE. WITH SFC HIGH
PRESSURE IN CONTROL AND A DRY AIRMASS IN PLACE...EXPECT SUNNY
SKIES. BASED ON THICKNESSES AND A BLEND OF MOS GUIDANCE...EXPECT
HIGH TEMPS TO RANGE FROM THE UPPER 40S (NORTH) TO LOWER/MID 50S
(52-54F) SOUTH.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
AS OF 300 PM TUESDAY...
UPPER TROUGH DROPS INTO THE NORTH CAROLINA MOUNTAINS FRIDAY EVENING.
WITH FLOW WEST TO NORTHWEST AHEAD OF THIS SYSTEM AT 5000 FEET AND
ANY COASTAL SURFACE LOW DEVELOPMENT WEAK AND WELL EAST... CENTRAL
NORTH CAROLINA APPEARS TO MISS OUT ON THIS EVENT AND BE DRY.
SURFACE HIGH PRESSURE BUILDS INTO THE STATE FROM THE WEST...
CENTERING OVER THE CAROLINAS SATURDAY NIGHT.
MODELS IN ROUGH AGREEMENT ON ANOTHER UPPER TROUGH DROPPING INTO
TENNESSEE MONDAY EVENING... WITH A DEVELOPING NORTH GULF COAST LOW
RISING NORTHEAST TOWARD THE CAROLINAS. GFS MODEL HAS A TENDENCY TO
OVERINTENSIFY THESE SYSTEMS SO TEMPERING THAT MODELS EXPECTATIONS.
HOWEVER TEMPERATURES ARE CLOSE TO FREEZING SUNRISE TUESDAY. WITH MID
LEVELS DRYING... A FEW SNOW FLAKES COULD END THE EVENT... BUT MORE
LIKELY SOME LIGHT FREEZING RAIN... MAINLY NORTHWEST. AT SEVEN DAYS
OUT... WITH IS WILD SPECULATION AND WILL TREAT IT AS SUCH AND KEEP
FORECAST ALL RAIN.
AFTERNOON HIGHS 45 TO 55 FRIDAY THEN 40S SATURDAY...LOW TO MID 50S
AFTER THAT. LOW TEMPERATURES NEAR FREEZING THURSDAY NIGHT THEN 20 TO
25 FRIDAY NIGHT. THEN A WARMING TREND TO UPPER 20S SATURDAY NIGHT...
NEAR FREEZING SUNDAY NIGHT...LOW TO MID 30S MONDAY NIGHT.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AS OF 120 AM WEDNESDAY...
LIFR CONDITIONS IN STRATUS...DRIZZLE AND FOG WILL PERSIST THROUGH
MID TO LATE MORNING (~14/15Z) AS SOUTHWEST FLOW JUST OFF THE SURFACE
OVERRUNS COOL...MOIST NORTHEAST FLOW AT THE SURFACE. CONDITIONS WILL
LIFT TO MVFR LATE MORNING TO EARLY AFTERNOON AS A WARM FRONT PUSHES
NORTH THROUGH THE REGION. LOW LEVEL WIND SHEAR WILL BE A THREAT THIS
MORNING THROUGH EARLY AFTERNOON (ROUGHLY 08-17Z) AS THE FLOW ABOVE
15 HUNDRED FEET STRENGTHENS TO 40 TO 50 KNOTS.
A COLD FRONT WILL APPROACH AND MOVE ACROSS CENTRAL NORTH CAROLINA
BETWEEN 15Z THIS MORNING AND 00Z THURSDAY. AS THE GRADIENT TIGHTENS
SURFACE WINDS COULD GUST TO AT LEAST 35 KNOTS DURING THE AFTERNOON.
WITH THE FRONTAL PASSAGE WILL ALSO COME THE THREAT OF MVFR CEILINGS
IN RAIN.
SOUNDING DATA SHOW RAPID DRYING BEHIND THE FRONT AS HIGH PRESSURE
BUILDS IN NORTH CAROLINA FROM THE WEST... THEREFORE WE CAN EXPECT A
CLEARING TREND IN THE WEST AFTER 00Z TONIGHT... SPREADING TO THE
EAST BY 09Z THURSDAY MORNING.
HIGH PRESSURE WILL CONTROL THE AREAS WEATHER THROUGH SUNDAY...
HOWEVER AN UPPER TROUGH MOVING ACROSS THE REGION FRIDAY THROUGH
EARLY SATURDAY MAY HAVE ENOUGH MOISTURE WITH IT TO ENHANCE THE
DEVELOPMENT OF CLOUDS BETWEEN 35 HUNDRED AND 5 THOUSAND FEET.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...VINCENT
LONG TERM...RLH
AVIATION...RHJ
AREA FORECAST DISCUSSION
NWS SALT LAKE CITY UT
237 PM MST THU JAN 29 2009
.SYNOPSIS...HIGH PRESSURE ALOFT WILL EXPAND EAST ACROSS THE
INTERIOR WEST THROUGH TOMORROW. A COUPLE OF WEAK WEATHER
DISTURBANCES WILL CROSS NORTHERN UTAH DURING THE
WEEKEND...BRINGING COLDER AIR AND A SLIGHT CHANCE OF LIGHT
PRECIPITATION TO THE REGION.
&&
.DISCUSSION...WATER VAPOR LOOP SHOWS A RIDGE BUILDING IN FROM THE
EASTERN PACIFIC. SHORT WAVES WERE BEGINNING TO ROUND THE RIDGE ALONG
150W. ACARS 400-250MB WIND OBSERVATIONS REVEAL THE UPPER LEVEL
TROUGH AXIS OVER CENTRAL UTAH...WITH RIDGING BUILDING IN FROM THE
NORTHWEST. 12Z 700MB ANALYSIS PLACED A BUILDING RIDGE OVER WESTERN
OREGON. WARM ADVECTION WAS INITIATING...WITH -14C AT KSLC AND -7C
UPSTREAM AT KBOI.
12Z KSLC RAOB INDICATES NEARLY NEUTRAL TEMPERATURE CHANGE THROUGH
THE COLUMN DURING THE PAST 24 HOURS...EXCEPT 3C OF COOLING FROM
800-700MB. THE PRECIPITABLE WATER VALUE WAS NEARLY STEADY AT A
QUARTER INCH.
COPIOUS CLOUDS AND SCATTERED LIGHT SNOW SHOWERS HAVE PERSISTED
ACROSS THE NORTHERN UTAH MOUNTAINS AND SOUTHWEST WYOMING THROUGH
MIDDAY. 1955Z DESCENT SOUNDING INTO SLC IS 6 TO 8C WARMER IN THE
600-700MB LAYER THAN THE 12Z RAOB AND THE INVERSION HAS LOWERED
FROM 680MB TO 750MB. AS WARM ADVECTION INCREASES...THE SNOW
PRODUCTION LAYER WILL CONTINUE TO DIMINISH AND THE COLUMN WILL
WARM SIGNIFICANTLY. THUS...EXPECT CONDITIONS WILL CONTINUE TO
IMPROVE DURING THE LATE AFTERNOON.
CLEAR SKIES AND LIGHT WINDS TONIGHT WITH HIGH PRESSURE IN PLACE.
COMBINED WITH FRESH SNOWPACK...HAVE UNDERCUT GUIDANCE TEMPERATURES.
LOCATIONS ACROSS NORTHERN FORECAST AREA WILL BE MUCH COOLER THAN
LAST NIGHT WHEN THE CLOUD COVER WAS IN PLACE. PATCHY FOG IS
EXPECTED IN THE CACHE VALLEY AND NEAR HEBER CITY WITH GOOD
RADIATIONAL COOLING CONDITIONS IN PLACE.
SUNNY AND WARMER OUTSIDE OF THE VALLEYS TOMORROW...WHILE HAZE BEGINS
TO BUILD UNDER THE LOWERING INVERSION WITHIN VALLEYS. HAZE CONTINUES
TO BUILD SATURDAY AS HIGHER LEVEL MOISTURE BEGINS TO INVADE AHEAD OF
THE NEXT SYSTEM.
GUIDANCE IS STILL CONSISTENT BRINGING A COLD FRONT THROUGH SATURDAY
NIGHT. DO NOT EXPECT PRECIPITATION IN THE VALLEYS GIVEN THE AMOUNT
OF DRY AIR IN PLACE...BUT DO INDICATE A SLIGHT CHANCE OF
PRECIPITATION IN THE MOUNTAINS WITH THIS SYSTEM. HOPING THAT THE
INVERSION IS ABLE TO MIX OUT SUNDAY AS -10C AIR ARRIVES AT 700MB.
12Z GFS HAS TRENDED TOWARD THE CONSISTENT EUROPEAN SOLUTION IN THE
EXTENDED...WITH ANOTHER RIDGE ALOFT BUILDING IN WITH A CUT OFF WEST
OF CALIFORNIA NEXT WEEK. THIS WOULD ALLOW A MORE SUBSTANTIAL AND
LONGER DURATION INVERSION TO DEVELOP...LIKELY LEADING TO REDUCED
VISIBILITIES. HAVE UNDERCUT MOS GUIDANCE MAX TEMPERATURES IN THE
EXTENDED ALONG THE WASATCH...CACHE VALLEY...AND UINTA BASIN. THE
FIRST OPPORTUNITY TO MIX OUT THE INVERSION NEXT WEEK WILL BE LATE
DURING THE WORK WEEK DEPENDING ON THE TIMING OF THE CUT OFF SYSTEM.
&&
.AVIATION...SCATTERED CLOUDS AROUND 5000FT AGL AT THE KSLC TERMINAL
WILL GIVE WAY TO MOSTLY CLEAR SKIES OVERNIGHT. NORTHWEST LAKE BREEZE
SHOULD SWITCH TO THE SOUTHEAST DRAINAGE PATTERN BY AROUND 03Z.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...NONE.
WY...NONE.
&&
$$
PUBLIC...ROGOWSKI
AVIATION...YOUNG
FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS SALT LAKE CITY UT
908 AM MST WED JAN 28 2009
.SYNOPSIS...A STRONG AND MOIST NORTHWEST FLOW WILL REMAIN OVER THE
AREA THROUGH TONIGHT. A RIDGE WILL BUILD INTO THE AREA THURSDAY THROUGH
FRIDAY...WITH A COLD FRONT EXPECTED LATE SATURDAY OR SATURDAY NIGHT.
&&
.DISCUSSION...WATER VAPOR LOOP SHOWS A RIDGE OVER THE EASTERN
PACIFIC. A WEAK UPPER LOW WAS LOCATED NEAR THE BERING SEA...WITH
DISTURBANCES ROUNDING THE RIDGE FROM THE GULF OF ALASKA THROUGH
WESTERN CANADA AND THE PACIFIC NORTHWEST. ACARS 400-250MB WIND
OBSERVATIONS REVEAL A 90-110KT NORTHWESTERLY JET FROM BRITISH
COLUMBIA INTO THE GREAT BASIN. 12Z 700MB ANALYSIS PLACED A RIDGE
CENTERED WEST OF CALIFORNIA...WITH A CYCLONE NEAR LAKE WINNIPEG. A
STRONG HEIGHT GRADIENT WAS IN PLACE IN BETWEEN...SUPPORTING 30-40KT
OF NORTHWEST FLOW.
12Z KSLC RAOB INDICATES +9C OF WARMING DURING THE PAST 24 HOURS
BETWEEN 700-800MB...WITH +7C OF WARMING CENTERED BETWEEN 400-500MB.
STRONG VEERING WAS NOTED WITH WIND SPEEDS INCREASING WITH HEIGHT TO
95KT. THE PRECIPITABLE WATER VALUE WAS JUST ABOVE A QUARTER INCH.
POSITION OF THE UPPER LEVEL JET WILL CONTINUE TO SUPPORT THE PASSAGE
OF SEVERAL WEAK SHORT WAVES FROM IDAHO ACROSS NORTHERN UTAH THIS
AFTERNOON. PERIODS OF LIGHT SNOW WILL RESULT...WITH ACCUMULATIONS
MAINLY RESTRICTED TO THE MOUNTAINS AND BENCHES. DRY AIR ACROSS
VALLEYS AS SAMPLED BY 12Z KSLC RAOB WILL BE TOUGH TO OVERCOME DUE TO
THE WEAK DYNAMICS AT PLAY TODAY. GIVEN THE TIGHT HEIGHT GRADIENT AT
700MB...WILL CONTINUE TO ADVERTISE BLOWING SNOW IN THE HIGHER
TERRAIN.
A WEAK COLD FRONT CAN BE PLACED FROM NORTHERN CALIFORNIA INTO
CENTRAL IDAHO THIS MORNING BASED ON PRESSURE RISES OF 1-3MB/3HR
ACROSS THE PACIFIC NORTHWEST. 12Z NAM/00Z GFS INDICATE THIS FEATURE
WILL CROSS NORTHERN UTAH ABOUT TIME FOR THE EVENING COMMUTE.
SNOWFALL RATES SHOULD INCREASE OWING TO THE STEEPENING LOW LEVEL
LAPSE RATES COMBINED WITH THE LIFT GENERATED BY THE FRONTAL SLOPE.
FURTHER SOUTH...WIND GUSTS ARE EXPECTED TO INCREASE FROM THE
NORTHEAST WITH THE PASSAGE OF THE COLD FRONT IN THE WASHINGTON
COUNTY CANYONS TONIGHT. WHILE NOTICEABLE...AT THIS TIME WIND GUSTS
APPEAR LIKE THEY WILL REMAIN BELOW ADVISORY CRITERIA. WILL
RE-ADDRESS WITH THE FULL SUITE OF 12Z DATA.
OTHERWISE THE FORECAST IS ON TRACK AND NO UPDATES TO THE GRIDS ARE
PLANNED. PREVIOUS DISCUSSION FOLLOWS.
PRECIPITATION WILL TAPER OFF TONIGHT AS THE SHORTWAVE AND JET
SUPPORT EXIT THE AREA...ALLOWING THE FLOW ALOFT TO BECOME MORE
NORTHERLY AS THE RIDGE OFF THE CALIFORNIA COAST BUILDS EASTWARD.
THIS WILL RESULT IN DRIER CONDITIONS FOR THURSDAY AND FRIDAY WITH
TEMPERATURES WARMING TO VALUES CLOSE TO SEASONAL NORMS.
THE RIDGE IS EXPECTED TO FLATTEN FRIDAY NIGHT AS A PACIFIC
NORTHWEST TROUGH MOVES ONSHORE...SHIFTING THE FLOW ALOFT TO THE
WEST. BOTH THE ECMWF AND GFS KEEP THIS TROUGH NORTH OF THE
AREA...THOUGH IT GETS CLOSE TO THE UT/ID BORDER IN THE GFS.
HOWEVER...IN BOTH MODELS...A DRY COLD FRONT MOVES THROUGH NORTHERN
UTAH SATURDAY AFTERNOON...AND THROUGH SOUTHERN UTAH BY SUNDAY
MORNING. YESTERDAY MORNINGS MODEL RUNS INDICATED SOME MOISTURE
WITH THE FRONT...SO THERE IS SOME RUN-TO-RUN INCONSISTENCY. EITHER
WAY...THOUGH...THE THREAT OF PRECIP APPEARS TO BE MINIMAL. COOLING
OF THE AIRMASS OVER THE REGION FROM THE FRONT IS EXPECTED TO BE
SHORT LIVED AS THE MODELS INDICATE STRONG RIDGING QUICKLY MOVING
IN FOR EARLY NEXT WEEK.
&&
.AVIATION...CEILINGS AT THE KSLC TERMINAL ARE EXPECTED TO REMAIN IN
THE VFR RANGE ABOVE 4000 FT THROUGH MOST OF THE DAY. OCCASIONAL
LIGHT SNOW OR FLURRIES WILL OCCUR WITH ONLY A 20 PERCENT CHANCE THAT
MVFR CONDITIONS WILL OCCUR WITH THE GREATEST THREAT LYING BETWEEN
20Z AND 23Z. WINDS WILL REMAIN SOUTHERLY UNTIL ABOUT 22Z AND THEN
SHIFT NORTHWEST.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER WEATHER ADVISORY UNTIL 8 PM WEDNESDAY FOR UTZ007-UTZ008-
UTZ009.
WY...NONE.
&&
$$
PUBLIC...ROGOWSKI/TRAPHAGAN
AVIATION...YOUNG
FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)
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