Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 01/10/13
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1006 AM MST TUE JAN 8 2013
.UPDATE...
&&
.SHORT TERM...MID LEVEL SHORT WAVE MOVING ACROSS EASTERN COLORADO
AT THIS TIME. WEAK SUBSIDENCE BEHIND WAVE ALONG WITH CROSS
MOUNTAIN FLOW OF 35 KTS COMBINED TO PRODUCE GUSTS AROUND 50 MPH
ALONG THE FOOTHILLS OF BOULDER AND JEFFERSON COUNTIES WITH THE
GJT-DEN 1500M PRESSURE GRADIENT AROUND 10.21 MB. WINDS STILL
EXPECTED TO DECREASE BY THE AFTERNOON AS NORTHWEST FLOW ALOFT
WEAKENS AND CROSS MOUNTAIN FLOW DECREASES TO AROUND 20 KTS.
CURRENT FORECAST TRENDS OF DECREASING WINDS STILL LOOKING
REASONABLE. A FEW LIGHT SNOW SHOWERS STILL POSSIBLE ALONG WEST
FACING SLOPES OF THE GORE AND PARK RANGES AS RAP CROSS SECTIONS
KEEP SOME MOISTURE TRAPPED IN THAT AREA. OTHERWISE...CLOUDS TO BE
ON THE DECREASE AS SUBSIDENCE AND DRIER AIR DOMINATES.
TEMPERATURES SLIGHTLY COOLER TODAY AS COLD AIR ADVECTION SPREADS
OVER AREA. CURRENT TEMPERATURE GRIDS STILL SEEM REASONABLE.
PERSISTANT SURFACE BASED INVERSIONS TO KEEP MOUNTAIN VALLEYS QUITE
COLD...ESPECIALLY OVERNIGHT.
.AVIATION...SOUTHWEST TO WEST WINDS ACROSS AREA AIRPORTS AT THIS
TIME. LATEST RAP AND HRRR INDICATING WINDS TO WEAKEN AND GO
CLOCKWISE DURING THE AFTERNOON...WITH NORTHEAST TO EAST WINDS AT
DEN AND APA. WINDS SHOULD REMAIN MORE NORTHWEST AT BJC. SPEEDS
SHOULD REMAIN BELOW 10 KTS...THOUGH SOME GUSTS TO 20 KTS WILL BE
POSSIBLE AT BJC. WILL BE MAKING ADJUSTMENTS TO THE DIRECTION TO
FOLLOW THE RAP/HRRR SOLUTIONS. VFR TO PREVAIL WITH CEILINGS ABOVE
10000 FEET.
&&
.PREV DISCUSSION... /ISSUED 355 AM MST TUE JAN 8 2013/
SHORT TERM...A COUPLE MID/HIGH LEVEL CLOUD BANDS PASSING OVER
THE FORECAST AREA AT THIS HOUR ASSOCIATED WITH A PASSING
SHORTWAVE TROUGH. NEXT FEW HOURS SHOULD SEE NORTHWESTERLY WINDS
ALOFT INCREASING WITH COLD ADVECTION. MODEL CROSS SECTIONS
INDICATE A 30-35 KT WEST-NORTHWEST MTN TOP WIND COMPONENT NOW
THROUGH 15Z THIS MORNING. COULD SEE GUSTY WESTERLY SFC WINDS OF
25-35 KTS DEVELOPING IN THE NEXT HOUR OR SO ON THE RIDGETOPS AND
EAST SLOPES OF THE FRONT RANGE. AREAS ALONG THE BASE OF THE
FOOTHILLS IN NRN JEFFERSON...BOULDER AND LARIMER COUNTIES COULD
ALSO SEE OCCASIONAL GUSTS OF 25-30 KTS THRU 15Z THIS MORNING. DO
NOT SEE MUCH IF ANY PRECIPITATION WITH THIS PASSING DISTURBANCE
AS THE SUB-CLOUD LAYER APPEARS QUITE DRY. LATER THIS MORNING
WITH THE TROUGH EXITING THE AREA...SHOULD SEE CLEARING AS WELL AS
A DECREASE IN WIND SPEEDS WITH THE FLOW ALOFT WEAKENING AND WITH
THE CROSS STATE PRESSURE GRADIENT RELAXING. LOOKING FOR HIGH
TEMPERATURES TODAY TO GENERALLY BE 2-3C ABOVE AVERAGE FOR THE
DATE...WITH MID 40S-LOWER 50S ON THE PLAINS...AND 20S-30S IN THE
HIGH COUNTRY. ALTHOUGH LOW LYING AREA IN THE HIGH MOUNTAIN
VALLEYS SUCH AS ALONG THE COLORADO RIVER IN MIDDLE PARK AND AROUND
ANTERO AND ELEVENMILE CANYON RESERVOIRS IN SOUTH PARK WILL ONCE
AGAIN STRUGGLE TO CLIMB ABOVE THE SINGLE DIGITS DUE TO A STRONG
AND PERSISTENT SFC BASED TEMPERATURE INVERSION. OVERNIGHT
NORTHWEST FLOW ALOFT IN THE EVENING TURNS ZONAL/WESTERLY AFTER
MIDNIGHT WITH HEIGHT RISES ACROSS UTAH AND WESTERN COLORADO.
TEMPERATURES TONIGHT WILL BE SLIGHTLY WARMER ON THE PLAINS AND AT
HIGHER ELEVATIONS. ALTHOUGH A STRONG NOCTURNAL INVERSION WILL
ONCE AGAIN RESULT IN ANOTHER NIGHT OF BITTER COLD TEMPERATURES...
AS MUCH AS 15 TO 20 F BELOW ZERO...FOR THOSE SAME MTN VALLEY
LOCATIONS MENTIONED ABOVE.
LONG TERM...WLY FLOW ALOFT WILL BE OVER THE AREA ON WED AND THEN
BECOME MORE SWLY ON THU AS AN UPPER LEVEL TROUGH DEVELOPS OVER THE
WRN US. OVERALL IT SHOULD BE DRY OVER THE RGN THRU THU WITH ABV
NORMAL TEMPS ACROSS NERN CO. HIGHS BOTH DAYS SHOULD BE IN THE 50S
ALONG THE FRONT RANGE WITH SLIGHTLY COOLER READINGS OVER THE FAR
NERN PLAINS.
FOR FRI INTO FRI NIGHT BOTH THE GFS AND ECMWF WANT TO MOVE THE
UPPER LEVEL TROUGH OVER THE WRN US QUICKLY EASTWARD ACROSS THE
AREA. SOME OF THE ENSEMBLE MEMBERS ARE SLOWER BUT FOR NOW WILL
TREND FCST WITH FASTER SOLUTION. MEANWHILE THERE WILL BE A STG
CDFNT MOVING INTO NERN CO DURING THE DAY ON FRI. BOTH THE GFS AND
ECMWF HAVE THIS FNT ACROSS MOST OF THE PLAINS BY AFTN SO WILL HAVE
HIGHS RANGING FM THE MID TO UPPER 20S NR THE CO-WY BORDER WITH
LOWER TO MID 40S ACROSS SRN LINCOLN COUNTY.
AS FAR AS SNOW RIGHT NOW IF THE CURRENT TIMING OF THE TROUGH IS
CORRECT THERE WILL BE A PERIOD OF DECENT QG ASCENT FRI AFTN INTO
FRI NIGHT WITH FAVORABLE LAPSE RATES. THUS SHOULD SEE SNOW IN THE
MTNS THRU THE DAY ON FRI INTO FRI NIGHT. OVER NERN CO WITH UPSLOPE
COMPONENT IN PLACE BEST CHC OF SNOW LOOKS TO BE FRI AFTN INTO FRI
FRI EVENING WITH ACCUMULATIONS CERTAINLY POSSIBLE.
BY SAT THE UPPER LEVEL TROUGH MOVES ENE OF THE AREA LEAVING NW
FLOW ALOFT OVER THE AREA. ENOUGH MOISTURE WILL LINGER IN THE MTNS
FOR A CHC OF LIGHT SNOW ALTHOUGH OROGRAPHIC COMPONENT IS VERY
WEAK. OVER NERN CO WEAK UPSLOPE COMPONENT IS SHOWN ALONG THE FRONT
RANGE THRU THE DAY WITH LINGERING LOW LEVEL MOISTURE AND DECENT
LAPSE RATES. THUS COULD SEE A CHC OF LIGHT SNOW MAINLY IN AND NR
THE FOOTHILLS THRU THE AFTN HOURS. TEMPS WILL BE MUCH COLDER ON
SAT AND IT WOULD NOT SURPRISE ME IF HIGHS DID NOT GET OUT OF THE
TEENS ACROSS NERN CO.
FOR SUN NNW FLOW ALOFT WILL REMAIN OVER THE AREA WITH STILL A CHC
OF LIGHT SNOW IN THE MTNS. OVER NERN CO IT SHOULD BE DRY WITH
TEMPS REMAINING WELL BLO NORMAL AS READINGS MAY STILL HAVE A HARD
TIME GETTING ABV 20 DEGREES ESPECIALLY IF THERE IS SNOW COVER. BY
MON THE FLOW ALOFT WILL BECOME MORE NWLY. ENOUGH MOISTURE MAY
STILL LINGER IN THE MTNS FOR A SLIGHT CHC OF LIGHT SNOW. OVER NERN
CO IT WILL BE DRY WITH TEMPS REMAINING WELL BLO NORMAL AS 850-700
MB TEMPS CHANGE VERY LITTLE.
AVIATION...MID AND UPPER LEVEL CLOUDS PASSING OVER THE DENVER
METRO AREA AT THIS EARLY HOUR MARK THE PASSAGE OF A WEAK UPPER
LEVEL LOW PRESSURE TROUGH. DO NOT EXPECT TO SEE CLOUD BASES
LOWERING MUCH BELOW 10 THOUSAND FT AGL NOW THROUGH 16Z THIS
MORNING. AFTER THAT...SHOULD SEE SKIES GRADUALLY CLEARING AS
CLOUD BASES RISE WITH DRIER NORTHWESTERLY FLOW ALOFT SPREADING
OVER THE AREA. WINDS NEAR THE FOOTHILLS SUCH AS AT BJC WILL BE
WEST-SOUTHWEST AT 10-15KT FOR MUCH OF THE DAY...WITH POSSIBLE
GUSTS TO AROUND 25 KTS NOW THROUGH 15Z. OTHERWISE SOUTH-
SOUTHWEST WINDS OF 8-13KTS WILL PREVAIL AT DIA AND APA TODAY...
ALTHOUGH MAY SEE A SHORT PERIOD OF WESTERLY WINDS OF 13-18 KTS
EARLY THIS MORNING WITH PASSAGE OF THE UPPER LEVEL TROUGH AXIS.
FOR TONIGHT UNDER CLEAR/MOSTLY CLEAR SKIES...DENVER AREA AIRPORTS
SHOULD SEE THE TYPICAL DRAINAGE WIND PATTERN SET UP WITH SUNSET
WITH SPEEDS GENERALLY UNDER 12KTS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....RPK
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
854 PM EST WED JAN 9 2013
.SYNOPSIS...
WEAK COLD FRONT SWINGS THROUGH THE REGION LATE TONIGHT INTO THURSDAY
MORNING. HIGH PRESSURE RE-ESTABLISHES ITSELF ACROSS THE AREA ON
THURSDAY AND SLOWLY MOVES OFF TO THE EAST THROUGH THE WEEKEND.
ANOTHER LOW PRESSURE SYSTEM WILL BEGIN TO IMPACT THE REGION LATE ON
SUNDAY AS IT PUSHES ITS ASSOCIATED COLD FRONT THROUGH THE AREA BY
MONDAY. THE FRONT SHOULD DROP TO OUR SOUTH ON TUESDAY AND WEDNESDAY
AS HIGH PRESSURE FILLS BACK IN.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
THE SHEET OF STRATOCUMULUS IS ABOUT TO EXIT SOUTHERN AND EASTERN
AREAS OF THE REGION...AND SHOULD BE OFFSHORE BEFORE MIDNIGHT. THERE
IS NOT MUCH IN THE WAY OF CLOUDINESS BEHIND IT...ASIDE FROM THE BAND
OF JET INDUCED CIRROSTRATUS ACROSS NORTHEAST MARYLAND AND CENTRAL
AND SOUTHERN DELAWARE.
BASED ON THE TRAJECTORY OF THE LOWER CLOUDS OVER NORTHERN NEW YORK
STATE AND OFF THE LAKES...THESE CLOUDS SHOULD REMAIN NORTH OF THE
AREA OVERNIGHT. ELSEWHERE...MAINLY JET INDUCED CIRRUS IS EXPECTED...
AS THE 150 KNOT JET AT 300 MB OVER WESTERN NEW YORK STATE ROARS BY
TO THE NORTH. A LARGER AREA OF CIRRUS...ASSOCIATED WITH WARM AIR
ADVECTION AHEAD OF THE CLOSED MID LEVEL LOW OVER TEXAS...MAY ARRIVE
LATE TONIGHT.
THE SURFACE COLD FRONT IS FAIRLY DIFFUSE AT THIS POINT...AND APPEARS
TO LIE ACROSS WESTERN AND CENTRAL NEW JERSEY AT 0000 UTC. BEHIND THE
FRONT...THE STRONGER WINDS HAVE BEEN CUT OFF BY THE LOW LEVEL
INVERSION IN PLACE. THE INVERSION SHOWS UP WELL ON THE 0000 UTC
SOUNDINGS AT KIAD AND KOKX. THE LOWER INVERSION MAY TAKE SOME TIME
TO BREAK...AND THE MOMENTUM TRANSFER WILL BE STYMIED THROUGH THE
EARLY MORNING HOURS.
THE EXCEPTION HERE COULD BE THE HIGHER TERRAIN. THE 0000 UTC
SOUNDINGS SHOWS 50 KNOTS OF WIND AT 850 MB. BECAUSE OF THE INVERSION
IN PLACE AT THE LOWER LEVELS...MIXING FROM THIS HEIGHT LOOKS
UNLIKELY. HOWEVER...THE HIGHER TERRAIN COULD FARE BETTER...AS IT IS
ABOVE THE LOWER INVERSION. WINDS ARE GUSTING BETWEEN 25 AND 30 KNOTS
AT KMPO...AND GUSTS OF THESE MAGNITUDES ARE POSSIBLE FOR MUCH OF THE
NIGHT ACROSS THE HIGHER TERRAIN.
PATCHY FOG AND HAZE STUBBORNLY REMAINS IN PLACE ACROSS PORTIONS OF
THE LEHIGH VALLEY AND NORTH CENTRAL NEW JERSEY...A CONSEQUENCE OF
THE LACK OF MIXING TODAY. FOR NOW...THIS WILL NOT BE INCLUDED IN THE
UPDATED FORECAST...BUT TRENDS BEAR WATCHING.
NO SIGNIFICANT CHANGES TO LOWS AT THIS POINT. THE LOWER LEVEL
INVERSION SHOULD EVENTUALLY WEAKEN OR EVEN MIX OUT. THESE PROCESSES
WOULD ALLOW WINDS TO MIX DOWN AND KEEP LOWS IN SHELTERED LOCATIONS
OF THE LEHIGH VALLEY AND NORTH CENTRAL NEW JERSEY FROM DROPPING TOO
LOW.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
AS JANUARY DAYS GO, UNLESS ONE IS LOOKING FOR SNOW, THURSDAY SHOULD
BE PRETTY PRETTY GOOD. THE NEXT HIGH PRESSURE SYSTEM WILL BE NEARING
AND THE RIDGE AXIS IS FORECAST TO STILL BE WEST OF OUR CWA. THE
FORECAST CONVECTIVE TEMPERATURE IS BEYOND REACH. WE ARE ONLY
EXPECTING SOME CIRRUS. VERY SHALLOW COLD, OK COOLER, AIR IN PLACE
FOR THE DAY. THE FORECAST WINDS ARE NOT EXPECTED TO BE THAT STRONG
AND NEITHER IS THE JANUARY SUN. SO THROUGH THE DAY, THE INVERSION
SHOULD HOLD AND WE WERE CONSERVATIVE WITH MAX TEMPS, LEANING TOWARD
A STAT GUIDANCE COMPROMISE. FULL SUN MACROS OFF THE GFS SOUNDINGS
SUPPORT NAM MOS MORE THAN GFS MOS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
5-WAVE MODEL GUIDANCE SHOWS THAT THE DOMINANT SOUTHEAST RIDGE VERY
SLOWLY FLATTENS OUT BY MID NEXT WEEK. THIS IS DUE TO DEEPER CENTRAL
UNITED STATES LONGWAVE TROUGHING AS A MASSIVE RIDGE BUILDS INTO THE
PACIFIC NORTHWEST.
HIGH PRESSURE RETURNS FOR A TIME PERIOD ON FRIDAY WHILE THE ONCE
STRONG SOUTHWEST CUT-OFF LOW EJECTS TOWARDS THE NORTHEAST AND
PASSES THROUGH THE GREAT LAKES. HAVING LOST ITS PHASING WITH A
NORTHERN STREAM SYSTEM AND UNABLE TO SUPPORT ITSELF ANY FURTHER, THE
LOW IS FORCED TO OPEN UP AS IT TRIES, BUT FAILS, TO CUT INTO THE TOP
OF THE EAST COAST RIDGE. IT THEN GETS PICKED UP BY THE 170KT JET
OVERHEAD AND IS SWEPT THROUGH THE NORTHEAST. DEPENDING ON HOW MUCH
REMAINING MOISTURE IS INVOLVED WITH THIS SYSTEM DICTATES HOW FAST WE
CAN SATURATE THE COLUMN AND SEE AN ACCUMULATING PRECIPITATION.
TEMPERATURES ACROSS THE NORTH WILL BE BELOW FREEZING FOR A FEW HOURS
DURING THE FORECASTED ONSET OF PRECIPITATION, I.E. FREEZING RAIN IS
POSSIBLE. THERE WAS AN EVENT MUCH LIKE THIS ABOUT A MONTH AGO WHERE
THE COLD AIR AT THE SURFACE WAS ERODED PRIOR TO ANY PRECIPITATION
FALLING DUE TO A VERY DRY COLUMN. THIS ONE LOOKS TO BE TRENDING IN
THE SAME DIRECTION ALTHOUGH NOT WITH THE TEMPERATURES RISING
OVERNIGHT BUT RATHER THE P-TYPE ISSUES.
BY LATE FRIDAY MORNING OUR SURFACES TEMPERATURES WILL ALL BE ABOVE
FREEZING WITH MORE RAIN ON THE WAY UP FROM THE SOUTHWEST...NORTHERN
ZONES HAVE THE HIGHEST CHANCES. THIS SHORTWAVE THEN SKIRTS OFF TO
THE NORTHEAST LATE FRIDAY NIGHT AND THE SOUTHEAST RIDGE
RE-ESTABLISHES ITSELF ALONG THE EAST COAST. THIS KEEPS A STRONG
SOUTHWESTERLY SURGE ALOFT ULTIMATELY ALLOWING TEMPERATURES TO CLIMB
WELL ABOVE NORMAL ON SATURDAY AND SUNDAY. THIS ALSO KEEPS MOST, IF
NOT ALL, THE SHORTWAVE ENERGY TO OUR NORTHWEST HEADING INTO SOUTHERN
ONTARIO. THE NEXT CHANCE OF PRECIPITATION WILL BE ON SUNDAY INTO
MONDAY AS A STRONGER COLD FRONT DROPS THROUGH FROM THE NORTHWEST.
THE SOUTHEAST RIDGE SHOULD KEEP THE FRONT FROM TRAVELING TOO FAR TO
OUR SOUTH. THIS WILL ALLOW THE BAROCLINIC ZONE TO FUNNEL A FEW MORE
PIECES OF ENERGY THROUGH OUR REGION ON TUESDAY AND WEDNESDAY. THE
MID-LEVEL FLOW TURNS A BIT MORE ZONAL AND THIS WILL ALLOW SOME
COLDER AIR TO BLEED INTO THE REGION FROM THE NORTHWEST...THOUGH WE
ARE NOT LOOKING AT A SUBSTANTIAL COOL DOWN BY ANY MEANS, MORE OF A
RETURN TO SLIGHTLY ABOVE NORMAL TEMPERATURES. IF TEMPERATURES CAN
COOL ENOUGH ALOFT ON WEDNESDAY WE COULD SEE A CHANGE OVER FROM RAIN
TO SNOW SHOWERS FALLING AS FAR SOUTH AS THE LEHIGH VALLEY. ALTHOUGH
WE WILL REMAIN MILD THROUGH A LOT OF THE EXTENDED WE WILL ALSO
REMAIN UNSETTLED.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
MAINLY VFR CONDITIONS CONTINUE EARLY THIS EVENING. THE LAST OF THE
MVFR VISIBILITIES SHOULD END BEFORE 0100 UTC AT BOTH KRDG AND KABE
AS DRIER AIR MIXES OUT THE LOW LEVEL MOISTURE. THE LOWER VFR
CEILINGS (WITH BASES NEAR 5000 FEET) EXTENDING FROM KPHL EAST
DISSIPATE BEFORE 0300 UTC THURSDAY...WITH HIGHER CEILINGS AT KMIV
AND KACY.
A COLD FRONT WILL CROSS THE AREA BETWEEN 0200 UTC AND 0600 UTC
THURSDAY FROM WEST TO EAST. AHEAD OF THE FRONT...WEST TO SOUTHWEST
WINDS SHOULD AVERAGE LESS THAN 10 KNOTS. BEHIND THE FRONT...WINDS
SHIFT TO THE WEST NORTHWEST...AND AVERAGE 10 KNOTS OR LESS. AFTER
THE LOWER CEILINGS EXIT...MAINLY HIGH CLOUDINESS IS EXPECTED THROUGH
SUNRISE.
VFR CONDITIONS ARE EXPECTED THURSDAY. IN THE WAKE OF THE COLD
FRONT...SUSTAINED WEST NORTHWEST WINDS SHOULD AVERAGE BETWEEN 8 AND
13 KNOTS...WITH THE HIGHEST WINDS AT KPHL AND KACY. THE AIRMASS IS
DRY...SO ONLY HIGH CLOUDINESS IS EXPECTED. WINDS SHOULD DROP BELOW 6
KNOTS AFTER 2200 UTC.
OUTLOOK...
THURSDAY NIGHT - FRIDAY MORNING...VFR.
FRIDAY - FRIDAY NIGHT...RAIN DEVELOPING EARLY IN THE DAY. MVFR AND
IFR CONDITIONS POSSIBLE WITHIN THE RAIN.
SATURDAY - SUNDAY...VFR.
SUNDAY NIGHT - MONDAY...RAIN DEVELOPING EARLY MONDAY MORNING. MVFR
OR LOWER POSSIBLE WITHIN SHOWERS.
&&
.MARINE...
WINDS ARE STARTING TO MIX IN THE WAKE OF THE COLD FRONT...AND SMALL
CRAFT WIND GUSTS SHOULD COMMENCE ACROSS THE NORTHERN OCEAN WATERS
BEFORE MIDNIGHT. FURTHER SOUTH...WHERE THE GRADIENT IS NOT AS
STRONG...MIXING COULD TAKE LONGER...ESPECIALLY ACROSS THE LOWER
DELAWARE BAY.
THE GRADIENT APPEARS TO SUPPORT SMALL CRAFT WINDS FOR JUST ABOUT ALL
WATERS OVERNIGHT...WITH A BETTER CHANCE ACROSS THE NORTHERN OCEAN
WATERS. THE LATEST RAP MODEL SOUNDINGS SUGGEST THAT THE STRONGEST
WIND GUSTS ACROSS THE NORTHERN OCEAN WATERS COULD OCCUR CLOSE TO
0900 UTC THURSDAY. THIS COULD MEAN THAT THE 600 AM END TIME FOR THE
SMALL CRAFT ADVISORY NORTH MAY BE A BIT SHORT.
FOR NOW...WILL HOLD OFF ON EXTENDING THE ADVISORY AND MONITOR TRENDS.
THE REST OF THURSDAY WILL BE SPENT WITH SUB SMALL CRAFT ADVISORY
CRITERIA AS THE HIGH PRESSURE SYSTEM GETS CLOSER.
OUTLOOK...
SUB-ADVISORY CONDITIONS ARE EXPECTED ACROSS OUR WATERS THROUGH THE
OUTLOOK PERIOD. THOUGH IT WILL BE AN ACTIVE PERIOD WITH MULTIPLE
SYSTEM PASSING THROUGH A LARGE SOUTHEAST UNITED STATES HIGH PRESSURE
SYSTEM WILL FORCE THESE SYSTEMS FAR TO OUR NORTH. THIS WILL KEEP THE
PRESSURE GRADIENT RATHER WEAK SO NOT EXPECTING WINDS AND SEAS TO
JUMP MUCH THROUGH THE PERIOD. WINDS WILL PREDOMINANTLY BE FROM THE
NORTH ON FRIDAY BEFORE SHIFTING TOWARDS THE SOUTH FOR THE WEEKEND
AND EARLY NEXT WEEK.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST THURSDAY FOR ANZ431-
450>455.
&&
$$
SYNOPSIS...HEAVENER
NEAR TERM...GIGI/HAYES
SHORT TERM...GIGI
LONG TERM...HEAVENER
AVIATION...HAYES/HEAVENER
MARINE...GIGI/HAYES/HEAVENER
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1046 AM EST TUE JAN 8 2013
.SYNOPSIS...
A WEDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION AND PREVAIL
THROUGH WEDNESDAY...WHILE A COASTAL TROUGH STRENGTHENS OFFSHORE. A
WEAK WARM FRONT WILL LIFT NORTH OF THE AREA THURSDAY AS A STORM
SYSTEM PASSES WELL TO THE WEST. ATLANTIC HIGH PRESSURE WILL THEN
PREVAIL INTO EARLY NEXT WEEK BEFORE A COLD FRONT APPROACHES FROM THE
WEST.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATE THIS MORNING...SURFACE ANALYSIS SHOWS THE REGION SOLIDLY
WITHIN THE LOW LEVEL RIDGE EXTENDING FROM THE 1032 MB HIGH LOCATED
NEAR THE CHESAPEAKE. ALOFT...NEARLY ZONAL FLOW DOMINATES WITHIN
THE SLIGHTLY ANTICYCLONICALLY CURVED SW FLOW. THE MAIN FORECAST
ISSUES FOR TODAY REVOLVE AROUND THE EXPECTED INCREASING CLOUD
COVER AND THE POTENTIAL FOR SHOWER DEVELOPMENT OVER THE COASTAL
WATERS CLOSER TO THE OFFSHORE COASTAL TROUGH. CURRENT CLOUD COVER
IS PRIMARILY COMPRISED OF MID/HIGH LEVEL CLOUDS...WITH SOME
PATCHES OF LOWER OVERCAST SPREAD AROUND PORTIONS OF GA AND SC. I
HAVE SLOWED THE PROGRESSION OF TOTALLY OVERCAST SKIES AND RAISED
TEMPS A DEGREE OR SO BASED ON MORE SUNSHINE THAN ORIGINALLY
THOUGHT. THIS STILL KEEPS HIGHS IN THE LOW 60S...EXCEPT FOR UPPER
50S FAR INLAND. BUT MODELS STILL SHOW CONSIDERABLE LOW LEVEL
MOISTURE SO AT SOME POINT LATER TODAY AND INTO THE EVENING WE
SHOULD BEGIN TO SEE A SOLID BLANKET OF STRATUS START TO DEVELOP.
REGARDING THE COASTAL TROUGH...IT IS NOT VERY SHARPLY DEFINED AT
THIS POINT AND ANY RESULTING SHOWER ACTIVITY IS QUITE WEAK AND
LOCATED WELL OFFSHORE. RECENT RUNS OF THE RUC SHOW A BROADER
COASTAL TROF THROUGH THE DAY WITH LESS COVERAGE OF SHOWERS WITHIN
THE WEAKER LOW LEVEL CONVERGENCE. AS SUCH...I HAVE KEPT POPS IN
THE SLIGHT CHANCE RANGE AND LIMITED THEM TO JUST THE COASTAL
WATERS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
TONIGHT...PRETTY MUCH THE SAME PATTERN WILL CONTINUE WITH INLAND
HIGH PRESSURE AND OFFSHORE LOW PRESSURE. EXPECT MOST OF THE
SHOWERS TO REMAIN OFFSHORE BUT COASTAL AREAS...ESPECIALLY ACROSS
SOUTHEAST GEORGIA...LOOK TO HAVE THE BEST SHOT AT SEEING A FEW.
WILL LIKELY SEE MORE IN THE WAY OF LOW CLOUDS AND SPRINKLES WITH
SOME FOG AS WELL. LOWS SHOULD RANGE FROM THE MID TO UPPER 40S
INLAND TO LOWER TO MID 50S ALONG THE COAST.
WEDNESDAY AND WEDNESDAY NIGHT...THERE IS INCREASING CONFIDENCE THAT
THE IN-SITU WEDGE OF HIGH PRESSURE WILL REMAIN ENTRENCHED OVER THE
AREA AS THE PARENT SURFACE HIGH SHIFTS OFF THE MID-ATLANTIC COAST
ALLOWING THE COASTAL TROUGH JUST OFFSHORE TO STRENGTHEN. ABUNDANT
LOW LEVEL MOISTURE AND MODEST ISENTROPIC ASCENT WILL BE ENOUGH TO
KEEP SKIES NEARLY OVERCAST WITH RATHER LOW CEILINGS EXPECTED. THE
BEST FOCUS FOR ANY SHOWERS WILL MAINLY BE NEAR THE COASTAL TROUGH
DUE TO ENHANCED LOW LEVEL CONVERGENCE...BUT ISENTROPIC ASCENT WILL
SUPPORT ADDITIONAL LIGHT PRECIPITATION INLAND AS WELL WHICH WILL
ONLY HELP TO REINFORCE THE WEDGE. THE FORECAST WILL INDICATE A
CHANCE OF SHOWERS FOR MOST OF THE AREA BY WEDNESDAY AFTERNOON...THEN
A SLIGHT CHANCE OF SHOWERS WEDNESDAY NIGHT. ALSO EXPECT AREAS OF FOG
AND POSSIBLY DRIZZLE TO TO FORM WEDNESDAY NIGHT...AND THE FOG COULD
BECOME DENSE AT TIMES.
DESPITE MOST OF THE GUIDANCE BEING ON BOARD INDICATING LOW CEILINGS
AND NORTH/NORTHEASTERLY WINDS ON WEDNESDAY...THEY ALL SHOW HIGHS
REACHING INTO AT LEAST THE LOWER 70S WITH LOW LEVEL THICKNESS VALUES
EVEN WARMER THAN THAT. THIS IS HARD TO BELIEVE GIVEN THIS
SCENARIO...AND FEEL THE MODELS MAY NOT HAVE A GOOD HANDLE ON THE LOW
LEVEL ENVIRONMENT. WILL THEREFORE CONTINUE TO FORECAST HIGHS ON
WEDNESDAY WELL BELOW GUIDANCE...RANGING FROM THE MID 60S INLAND TO
NEAR 70 ACROSS NORTH COASTAL GEORGIA AND NEAR THE ALTAMAHA RIVER.
THURSDAY AND THURSDAY NIGHT...A COMBINATION OF A WARM FRONT AND
COASTAL TROUGH WILL BEGIN TO LIFT NORTHWARD AS UPPER LEVEL RIDGING
BUILDS OVER THE SOUTHEASTERN U.S. IN RESPONSE TO A STORM SYSTEM
LIFTING NORTHEAST INTO THE MISSISSIPPI VALLEY. THIS WILL ALLOW FOR
THE GRADUAL EROSION OF THE IN-SITU WEDGE. LOW CLOUDS AND FOG WILL
LINGER INTO AT LEAST THE MORNING HOURS...BEFORE SOME PARTIAL
CLEARING OCCURS LATER IN THE DAY. SEA FOG COULD FORM JUST OFF THE
COAST AND POSSIBLY ADVECT INLAND AT JUST ABOUT ANY TIME. THERE COULD
BE SOME ISOLATED TO SCATTERED SHOWERS AROUND...WITH THE GREATEST
COVERAGE ACROSS SOUTHEAST SOUTH CAROLINA IN CLOSER PROXIMITY TO THE
WARM FRONT MAINLY DURING THE DAY THURSDAY. THE BUILDING RIDGE AND
LIFTING WARM FRONT WILL ALLOW TEMPERATURES TO SOAR TO HIGHS IN THE
LOWER 70S ON THURSDAY...WITH ANOTHER WARM NIGHT EXPECTED THURSDAY
NIGHT.
FRIDAY...A PASSING SHORT WAVE DISTURBANCE WILL CAUSE THE UPPER RIDGE
TO FLATTEN SOME IN THE MORNING...BUT A DEEP SOUTHERLY FLOW AROUND
ATLANTIC HIGH PRESSURE WILL ALLOW FOR TEMPERATURES TO CONTINUE TO
CLIMB. HIGHS ARE FORECAST TO BE IN THE MID TO UPPER 70S ACROSS MUCH
OF THE AREA AWAY FROM THE COAST. SUFFICIENT LOW LEVEL MOISTURE AND
THE PASSAGE OF THE SHORT WAVE COULD SUPPORT ISOLATED SHOWERS ACROSS
THE AREA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MEDIUM RANGE GUIDANCE IS IN EXCELLENT AGREEMENT THROUGH THE WEEKEND
INDICATING A STRONG UPPER LEVEL RIDGE OVER THE REGION...WHILE
ATLANTIC HIGH PRESSURE PREVAILS AT THE SURFACE. STRONG SUBSIDENCE
AND A LACK OF DEEP MOISTURE WILL KEEP CONDITIONS RAIN-FREE. THE
BIGGER STORY WILL BE THE UNSEASONABLY WARM...IF NOT HOT FOR THIS
TIME OF YEAR...TEMPERATURES. HIGHS OVER THE WEEKEND SHOULD BE WELL
INTO THE UPPER 70S AWAY FROM THE COAST...WITH SOME 80 DEGREE
READINGS CERTAINLY POSSIBLE. THESE HIGHS WILL BE APPROACHING RECORD
TERRITORY.
GUIDANCE BEGINS TO DIVERGE A BIT EARLY NEXT WEEK WITH RESPECT TO THE
TIMING OF A COLD FRONT AS IT APPROACHES FROM THE WEST AND SLOWS AS
IT ENCOUNTERS THE UPPER RIDGE. THE FORECAST WILL INDICATE A SLIGHT
CHANCE OF SHOWERS ON MONDAY WITH PROBABILITIES INCREASING INTO THE
CHANCE CATEGORY ON TUESDAY AS THE FRONT NEARS. TEMPERATURES SHOULD
MODERATE SOME...BUT OVERALL REMAIN WELL ABOVE NORMAL.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
A WEDGE OF HIGH PRESSURE WILL BECOME BETTER ESTABLISHED TODAY AS A
COASTAL TROUGH STRENGTHENS OFFSHORE. THIS WILL ALLOW ABUNDANT LOW
LEVEL MOISTURE TO BECOME TRAPPED BENEATH AN INVERSION...RESULTING
IN STRATUS THROUGH MOST OF THE FORECAST PERIOD. CEILINGS SHOULD
BORDER THE VFR AND MVFR CATEGORIES FOR MOST OF THE AFTERNOON...BUT
PREFER TO KEEP IT PREVAILING VFR UNTIL THERE IS A BETTER
INDICATION TO WHEN LOWER CEILINGS WILL DEVELOP. THE POTENTIAL FOR
LOWER CEILINGS WILL INCREASE THIS EVENING AS THE INVERSION
LOWERS. WILL INDICATE MVFR CEILINGS AT BOTH TERMINALS AFTER ABOUT
23Z...WITH IFR CEILINGS AT KSAV AFTER 07Z. PATCHY FOG COULD ALSO
REDUCE VISIBILITIES OVERNIGHT.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CEILINGS ARE LIKELY INTO
THURSDAY. FOG COULD ALSO REDUCE VISIBILITIES TO MVFR OR LOWER LEVELS
AT TIMES DURING THE LATE NIGHT/EARLY MORNING HOURS INTO THE WEEKEND.
&&
.MARINE...
TODAY AND TONIGHT...A TROUGH OF LOW PRESSURE IS EXPECTED TO REMAIN
OVER THE LOCAL WATERS THROUGH TONIGHT WHICH WILL LEAD TO A VARYING
WIND DIRECTION/SPEED FORECAST AS THE WESTERN SIDE OF THE TROUGH
NEAR THE COAST WILL SEE ENHANCED NORTHEAST WINDS WHILE THE EASTERN
SIDE SEES LIGHTER EASTERLY WINDS. DO NOT ANTICIPATE ANY
HEADLINES OTHER THAN THE EXISTING ADVISORY FOR THE WATERS BEYOND
20 NM UNTIL EARLY AFTERNOON WHERE SEAS REMAIN ELEVATED IN THE
NORTHEAST FLOW. MARINERS SHOULD ALSO BE ALERT FOR SOME FOG
DEVELOPING LATE TONIGHT...ESPECIALLY ACROSS THE COOLER NEARSHORE
WATERS ALONG THE GEORGIA COAST...AS A MORE HUMID AIRMASS SPREADS
INTO THE AREA.
WEDNESDAY THROUGH SUNDAY...A COASTAL TROUGH WILL PERSIST OVER OR
NEAR THE WATERS ON WEDNESDAY...BEFORE LIFTING NORTH AS A WARM FRONT
ON THURSDAY. THERE COULD BE SOME PINCHING OF THE GRADIENT EARLY
WEDNESDAY KEEPING THE NORTHEAST FLOW SOMEWHAT ELEVATED...HOWEVER THE
GRADIENT WILL WEAKEN AS THE FLOW VEERS TO THE SOUTHEAST THROUGH
THURSDAY. A SOUTH-SOUTHWEST FLOW WILL THEN PREVAIL THROUGH THE
WEEKEND DUE TO THE INFLUENCE OF ATLANTIC HIGH PRESSURE. WINDS ARE
EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA THROUGH THE
PERIOD...ALTHOUGH A FAVORABLE FETCH COULD BUILD SEAS TO 6 FT OVER A
PORTION OF THE OUTER GEORGIA WATERS LATE THURSDAY AND FRIDAY. THERE
IS A RISK OF SEA FOG OVER THE COOL NEARSHORE WATERS BEGINNING
WEDNESDAY ACROSS THE GEORGIA NEARSHORE WATERS AND SPREADING NORTH LATE
IN THE WEEK AND POSSIBLY INTO THE WEEKEND...AS A WARM AND MORE
HUMID AIRMASS ADVECTS INTO THE AREA.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR AMZ374.
&&
$$
NEAR TERM...BSH
SHORT TERM...RJB/JAQ
LONG TERM...JAQ
AVIATION...JAQ
MARINE...RJB/JAQ
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
645 PM EST WED JAN 9 2013
.AVIATION...
CONDITIONS WILL JUST BEGIN TO DETERIORATE AT THE END OF THIS VALID
PERIOD AS DEEPER MOISTURE AND RAINFALL APPROACH FOR THURSDAY NIGHT.
MOSTLY CLEAR SKIES AND LIGHT WINDS TONIGHT MAY ALLOW SOME BR TO
FORM. NAM BUFKIT SOUNDINGS SHOW SATURATED LAYER FROM SURFACE TO
500FT OVERNIGHT. HRRR SHOWING VERY LITTLE MOISTURE. MELTING SNOW
TODAY DID PROVIDE SOME BOUNDARY LAYER MOISTURE BUT LATEST OBS
SHOWING DEW POINTS DROPPING INTO LOWER 20S UNDER RIDGE AND HIGH THIN
CLOUDS ALREADY STREAMING IN. THIS MAY BE ENOUGH TO KEEP BR TO MVFR
CATEGORY SO CONTINUED THIS TREND IN TAFS. CLOUDS THICKEN AND LOWER
AT TAF SITES THURSDAY. RAIN POSSIBLE AFTER 21Z BUT CONDITIONS
EXPECTED TO REALLY DETERIORATE AROUND 00Z SO LEFT LOWER MENTION OUT
OF THESE TAFS. OUTLOOK FOR THURSDAY NIGHT INTO FRIDAY MORNING
SUGGEST IFR CONDITIONS A HIGH PROBABILITY WITH RAIN. WIND SHEAR WILL
ALSO BE POSSIBLE THU NIGHT.
&&
.SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT
AFTERNOON WATER VAPOR IMAGERY REVEALS LARGE SCALE PATTERN EVOLUTION
BEGINNING TO TAKE SHAPE WITH HIGH AMPLITUDE LONGWAVE TROUGH DIVING
INTO CALIFORNIA. THIS TROUGH WILL PROVIDE THE IMPETUS FOR CUTOFF
UPPER LOW MEANDERING ACROSS MEXICO TO EJECT NORTHEAST. LOW LEVEL
RIDGE AXIS NOW FIRMLY IN PLACE JUST TO OUR SOUTH/WEST WILL SLOWLY
DRIFT EASTWARD TONIGHT. WEAK PRESSURE GRADIENT COUPLED WITH ABSENCE
OF ANY APPRECIABLE TROPOSPHERIC MOISTURE WILL SUPPORT EXCELLENT
RADIATIONAL COOLING TONIGHT. RESIDUAL SNOWPACK HAS DWINDLED
SIGNIFICANTLY...SAVE FOR THE FAR SOUTHEAST...SO TEMPS LIKELY WONT
BOTTOM OUT TOO MUCH BUT LOW 20S MAY BE POSSIBLE IN SOME AREAS AND
HAVE NUDGED THE FORECAST TOWARD THE COOLER SIDE OF 12Z MOS GUIDANCE.
SURFACE HIGH WILL SHIFT TO THE EAST COAST BY TOMORROW WITH POSITIVE
FEEDBACK MECHANISMS FORCING IMPRESSIVE MIDLEVEL HEIGHT RISES OVER
THE GREAT LAKES AHEAD OF THE APPROACHING SOUTHERN STREAM PV ANOMALY.
NOT SURPRISING THEN THAT THE LATEST NCEP MODEL RUNS HAVE CONVERGED
ON THE SLOWER SOLUTION LONG ADVERTISED BY THE ECMWF. 295K SYSTEM
RELATIVE ISENTROPIC ASCENT INCREASES PRECIPITOUSLY BY THURSDAY
AFTERNOON WITH A VERY IMPRESSIVE SLUG OF LOW LEVEL THETA-E
ALONG/BEHIND THE WARM FRONT FORCING ALMOST IMMEDIATE SATURATION.
TIMING OF THIS LEAD WAA ARM PUTS PRECIP BEGINNING OVER OUR SOUTHERN
CWA BY MIDAFTERNOON AND ENGULFING THE ENTIRE AREA BY 00Z THURSDAY
EVENING. WITH THE LATER ONSET...LOW LEVEL WET BULB TEMPS LOOK TO BE
ABOVE FREEZING BY THE TIME PRECIP BEGINS SO THE CHANCES FOR A VERY
BRIEF MIX ON THE LEADING EDGE APPEAR QUITE LOW. AFTERNOON TEMPS WILL
LIKELY BE IN THE LOW TO MID 40S AND AFTER A BRIEF DROP EARLY IN THE
EVENING...WILL ACTUALLY RISE INTO THE MID TO UPPER 40S BY EARLY
FRIDAY MORNING. MAY BE A BRIEF LULL IN THE STEADIER PRECIP BY LATE
EVENING AFTER THE WARM FRONT LIFTS NORTH AND BEFORE THE VORT MAX
APPROACHES BUT PERIODS OF MODERATE TO HEAVY RAIN WILL QUICKLY
RETURN AFTER MIDNIGHT. IMPRESSIVE CVA WILL INCITE A MARKED INCREASE
IN 700MB OMEGA VALUES. THIS COUPLED WITH STRONG WARM/MOIST AIR
ADVECTION ALONG A DEVELOPING 60+ KNOT LOW LEVEL JET WILL ENSURE
WIDESPREAD RAINFALL. NO SHORTAGE OF AVAILABLE MOISTURE WITH PW
VALUES CLIMBING TO OVER 1.25 INCHES...WELL ABOVE THE 99TH
PERCENTILE FOR THIS TIME OF YEAR. COMBINATION OF EXCEPTIONALLY
WARM 900MB TEMPS AND STRONG MIDLEVEL HEIGHT FALLS WILL BRING THE
THREAT OF ELEVATED CONVECTION. BUFR SOUNDINGS NOT ALL THAT
IMPRESSIVE FOR THUNDER POTENTIAL BUT SUPPOSE 100-200 J/KG MUCAPE
WARRANTS ISOLATED MENTION FOR NOW. COMBINATION OF STRONG FORCING
WITH ABUNDANT MOISTURE AND NEUTRAL/SLIGHT STATIC INSTABILITY
SUPPORT STORM TOTAL RAIN AMOUNTS ON THE ORDER OF 0.5-0.75 INCHES
WITH LOCALIZED AMOUNTS AROUND AN INCH POSSIBLE IF CONVECTION
MANAGES TO DEVELOP.
&&
.LONG TERM...
LG SCALE CONUS PATTN CHG ALOFT COMMENCING THIS AFTN W/TREMENDOUS JET
ENERGY CARVING OUT DEEP TROUGHING ACRS THE EPAC AND BEGINNING TO
DISLODGE POTENT SRN STREAM SW OVR OLD MEXICO.
EWD PROGRESSION/BREAKUP OF DEEP WRN TROUGH STILL REMAINS SOMEWHAT
UNCERTAIN BUT CERTAINLY MUCH BTR MED RANGE AGREEMENT EXISTS TDA AS
OP GFS HAD TRENDED SHARPLY TWD PRIOR STRONGLY PREFERRED ECMWF
SOLUTION MID NXT WEEK W/HANDLING OF SWWD ELONGATING UPR TROUGH AXIS
AND YET ANOTHER STOUT SRN STREAM SW CUTTING OFF BY MID WEEK. DETAIL
DIFFS MOST TANTAMOUNT TO THIS FCST ARE PIECEMEAL NEWD EJECTION OF
INDIVIDUAL DISTURBANCES OUT OF DEEP WRN TROUGH...MOST IMPORTANT TO
THIS CYCLE IS W/SECOND IMPLIED SW EJECTING OUT THROUGH W TX LATE
SATURDAY THEN NEWD THROUGH THE WRN LAKES SUN AND POSITIONING OF NRN
STREAM SPLIT ACRS SRN CANADA. THUS MOST SIG DIFF IN MODEL SOLUTIONS
LIES W/PLACEMENT OF STALLED FNTL ZONE INVOF THE OH VALLEY IN
BETWEEN. WHILE NO INDIVIDUAL DETERMINISTIC SOLUTION CAN BE
DISCOUNTED ENTIRELY...MEAN CONSENSUS PLACES THIS FTR ALG A SW
INDIANA-NW OHIO LINE SAT NIGHT TIMED W/LIFTOUT OF SFC WAVE AND IN
AGREEMENT W/CIPS ANALOGS WHICH INDICATE STG POTENTIAL FOR SWATCH OF
1.5-2.0 INCH RAINS. STG BAROCLINICITY XPCD ALG THIS FTR W/ARCTIC AIR
INTRUDING THROUGH THE UPR MIDWEST AND MOIST GOMEX AIRMASS ADVTG UP
ACRS THE OH VALLEY. THETA-E RIDING IN ASSOCN/W THIS FTR MEANINGFUL
AS IT RELATES TO THE FCST W/CONVN QUITE PSBL AND INHERENT HEAVY RAIN
THAT MAY RESULT PER SIG NWD MSTR FLUX INTO STALLED FNTL BNDRY. WHILE
CONTD DROUGHT CONDS AND HISTORICALLY LOW STREAMFLOWS SUBDUE OVERALL
FLOOD THREAT...COMBINATION OF SYS IN SHRT TERM AND THIS SYS MAY YET
YIELD FLOODING CONCERNS ESP SE HALF IN PROXIMITY OF ADDNL INPUT OF
RAPID SNOWPACK RELEASE AND FROZEN GROUND. WILL AWAIT AN ADDNL MODEL
CYCLE OR TWO TO MONITOR GUIDANCE TRENDS BUT A NON-ZERO FLOOD THREAT
EXISTS AT THIS POINT.
REMAINDER OF THE PD THROUGH DY7 QUITE AS NRN STREAM BUCKLES SWD ACRS
ERN CANADA BRINGING SEASONABLY COLD AIR BACK INTO THE AREA DYS6-9.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 1 AM EST THURSDAY FOR LMZ043.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LMZ046.
&&
$$
SHORT TERM...AGD
LONG TERM...T
AVIATION...LASHLEY
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1020 PM EST WED JAN 09 2013
.Forecast Update...
Issued 1019 PM EST Wed Jan 9 2013
Social media communications and surface obs show that the fog in the
Blue Grass has become thicker and more dense in spots, so have
introduced patchy dense fog (in addition to the patchy fog already
in the forecast) to our eastern counties. Also went ahead and put
out a SPS for patchy dense fog primarily from Carlisle to Liberty.
Issued at 842 PM EST Wed Jan 9 2013
A few ASOS locations as well as a couple of public reports have
shown that patchy fog has developed across southern and eastern
portions of the CWA. The HRRR actually shows this as well, at least
along the eastern edge of the CWA. Surface analysis shows a
corridor of lower dew point depressions reaching northeastward from
middle Tennessee into eastern Kentucky. Of course we`ve been
concerned with the incoming rain maker, but first, surface high
pressure is still sprawled across the region from the
mid-Mississippi Valley to the Carolinas, keeping winds light. So,
have added patchy fog to the forecast roughly along and southeast of
a Bowling Green-Lexington line. Will let the fog dissipate as rain
moves in and northeast breezes begin to pick up a little later
tonight.
Have also decided to throw in some patchy fog from northern Dubois
County to northern Washington County IN. Dew point depressions are
tightening there and those areas have the added factor of melting
snowcover. A few locations in the Wabash Valley have already
reported some light fog.
In addition, have adjusted the temperatures a bit, especially in the
usual cool spots.
A dense cirrus shield has overspread the region so we have increased
cloud cover to overcast for the rest of the night.
&&
.Short Term (Tonight through Thursday Night)...
Issued at 320 PM EST Wed Jan 9 2013
The weak tail end of a cold front passing mostly over southern
Indiana, northern KY, and locations northeast was located just south
of the Ohio River as of 1945Z. To the southeast of the front, a
thick deck of mid level clouds exists. However, this deck is making
steady progress eastward. Expect skies to go only partly cloudy for
a good portion of this evening before thick, low clouds start to
creep back in from the south after midnight.
After midnight a warm front will approach from the south as part of
a strengthening low pressure system over the OK/TX region. As this
weather system moves northeast to the western Great Lakes by Friday
morning, it will bring us 2 notable rounds of showers/isld storms
late tonight through Friday morning. The first round of elevated
showers/isld storms will come just after midnight tonight and
through tomorrow afternoon as the warm front lifts north through the
area. 6Z/12Z models have been slower with the arrival of these
rains so trended POPs back in time accordingly. We should see a
broad area of light rains slowly move north through the area for
much of Thurs. Any t-storms would likely be elevated north of the
warm front. However, some of the higher res model data suggests a
few scattered cellular structures during the late afternoon/evening
hours Thurs. Still these cells should be of little to no
consequence as morning clouds/rains will rob most areas of heating/
instability. The best chance for any scattered t-storms redeveloping
late Thurs afternoon/evening in the warm sector would be over south
central KY. Total QPF from this first wave of rainfall would be
under a half inch over most locations with areas along and west of
I-65 receiving the most rainfall.
The second wave of rains/isld t-storms will be late Thurs night into
Friday morning with the passage of a cold front. Before then, we
may continue to see scattered rains across the area Thurs evening.
The cold front looks to bring a solid line of rains with embedded
thunder through the area as it will be accompanied by a strong LLJ
(60-70 kts @ h85) and upper level jet support as the potent upper
trough passes just to our northwest. Friday morning would be our
best chance to see some strong to possibly marginally severe storms
due to such a strong LLJ passing through the area. A decent low
level inversion should keep most of the strongest winds aloft.
Still would not be surprise to see 35-50 mph winds mixing down
inside and outside of convection Friday morning. Small hail may
also be possible, but gusty winds and brief heavy rainfall would be
the main threats if any from storms Friday morning.
As far as temps go, they will be tricky over the next 36 hrs as
multiple frontal boundaries push through the area. Lows tonight
will range from the lower 30s over southern Indiana to mid and upper
40s over south central KY as a left over boundary stalls over the
region. Tomorrow expect highs ranging from the upper 40s north to
mid 60s south as we get a warm surge during the afternoon hours.
Thurs night, we`ll likely see a decrease in temps during the evening
hours with lows being reached just after midnight. A warm surge
will occur just ahead of cold front passage Friday morning allowing
temps to warm near dawn. Lows Thurs night should be in the upper
40s to around 60.
.Long Term (Friday through Wednesday)...
Issued at 305 PM EST Wed Jan 9 2013
...Wet and Unsettled Pattern Will Continue...
A building ridge off the Atlantic Coast and a digging western trough
will put the lower half of the Mississippi River Valley and the
entire Ohio River Valley under strong southwest flow aloft. This
will pump in plenty of moisture via an atmospheric river from the
Gulf, and set the stage for a very wet and active long term period.
The cold front associated with our first low pressure system
Thursday night will be entering our western forecast area around
daybreak Friday. Guidance continues to indicate instability will
decrease Thursday night into Friday morning, with some elevated
instability remaining. With the frontal passage at a diurnally
unfavorable time of day, the scenario projected by guidance is
reasonable. So, surfaced-based severe weather is looking less
likely. Surface-based instability will increase a bit through the
day Friday, as high temperatures warm well above normal into the low
and mid 60s. However, shear and large-scale forcing will decrease.
So, will continue with small hail and isolated strong wind gusts
being the main threats.
As this system departs Friday, it will leave behind a stalled
frontal boundary to our northwest that will not move much through
the weekend. Multiple shortwaves will ride over this boundary in
southwest flow aloft, with the first wave of rainfall expected
Saturday afternoon into Sunday. This band of rain should set up
across our northwestern forecast area for the overnight hours. The
rain will diminish a bit Sunday. However, another wave is expected
Sunday afternoon and evening, with yet another wave Sunday night
into Monday. With each wave, the southwest-northeast oriented
rainfall band will slowly track southeast.
Very warm temperatures and near record PWAT for this time
of year will be ushered in from the Gulf, with very high sub-cloud
layer relative humidity and warm cloud depth values in the 10-12Kft
range expected. This sets the stage for high precipitation
efficiency. Area average accumulations of 2-3 inches will be common
from Friday night through the day Monday, with locally higher
amounts possible. With this rain falling on wet ground provided by
the Wednesday and Thursday night/Friday systems, there could be some
areal flooding and rising rivers. Please see the hydrology section
below for more details on river impacts.
The surface front will sag southeast Sunday night, with some cooler
air filtering into our northern forecast area. Probabilistic and
plume data depict a small chance of some mixed precip on the back
side of the system. So, could see some mixed precip late Sunday
night through Monday morning before the system/deep moisture
departs. At this time, do not believe this will cause much of an
impact given the warm ground of late. Will monitor the thermal
profile and deep moisture over the next few model cycles.
As for temperatures, highs Saturday will reach the mid and upper
60s, with a cooling trend expected into Monday as the front slowly
pushes southeast. Highs Monday will range from the mid 30s in the
northwest to around 50 in the southeast. Low temperatures will show
a similar trend, with 40s and 50s Saturday night giving way to 20s
and 30s Monday night.
Guidance differs on the arrival of the next system, but ensemble
data suggests another round of precip Tuesday through Tuesday night.
With the surface boundary projected to be southeast of the forecast
area, cooler air in place across the forecast area, and steady
northeast surface winds, we could see another mixed precip event.
Confidence is not high on the overall thermal profile and placement
of precip, given the differences in model solutions, but ensemble
probabilities suggest a chance of mixed precip. Will continue to
monitor run-to-run model solutions for this system as well. It does
appear the system will exit the area Wednesday, with dry conditions
to follow. High temperatures Tuesday appear to range from mid 30s to
mid 40s, with highs a couple degrees cooler Wednesday. Overnight
lows will trend cooler as well, with generally mid 20s to low 30s
possible by Wednesday night.
&&
.Aviation (00Z TAF Issuance)...
Issued at 630 PM EST Wed Jan 9 2013
Flying conditions will deteriorate significantly during this TAF
period. A weakening upper level disturbance moving from Texas to
Missouri will pull a large area of rain northeastward along with
it. Rain will move into the BWG area after midnight tonight and
make it to the northern TAF sites by morning. The rain will then
continue through midday with low ceilings and MVFR visibilities
(possibly IFR at BWG).
During the afternoon hours a warm front will pass from south to
north across Kentucky, which will allow the rain to become more
scattered and will allow ceilings to rise a bit, though probably
stay MVFR.
Winds will gradually shift from northeast tonight to the east
tomorrow morning and to the southeast tomorrow afternoon as the warm
front approaches and passes on through.
&&
.Hydrology...
A series of winter storms are forecast to move across the Ohio
Valley starting early Thursday morning. The first wave is expected
to deliver up to an inch of rainfall. However, soils are not frozen
and still fairly dry, especially in western Kentucky, so little
runoff is expected.
The more important storm system is expected this weekend when a
series of waves along with copious amounts of moisture will make for
a couple of wet days. Over the entire 3 days, areas should average
between 2 and 3 inches of rain with the heavier amounts over
southern Kentucky. This rain will cause streams to rise and some
near bankfull crests could occur. However, since the rain will be
spread out over several days and current streamflows are not
elevated, any flooding that may occur should be minor. The best
chance for flooding will be in the western portion of the Green
River Basin.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........13
Short Term.......AMS
Long Term........MJP
Aviation.........13
Hydrology........CMC
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
842 PM EST WED JAN 09 2013
.Forecast Update...
Issued at 842 PM EST Wed Jan 9 2013
A few ASOS locations as well as a couple of public reports have
shown that patchy fog has developed across southern and eastern
portions of the CWA. The HRRR actually shows this as well, at least
along the eastern edge of the CWA. Surface analysis shows a
corridor of lower dew point depressions reaching northeastward from
middle Tennessee into eastern Kentucky. Of course we`ve been
concerned with the incoming rain maker, but first, surface high
pressure is still sprawled across the region from the
mid-Mississippi Valley to the Carolinas, keeping winds light. So,
have added patchy fog to the forecast roughly along and southeast of
a Bowling Green-Lexington line. Will let the fog dissipate as rain
moves in and northeast breezes begin to pick up a little later
tonight.
Have also decided to throw in some patchy fog from northern Dubois
County to northern Washington County IN. Dew point depressions are
tightening there and those areas have the added factor of melting
snowcover. A few locations in the Wabash Valley have already
reported some light fog.
In addition, have adjusted the temperatures a bit, especially in the
usual cool spots.
A dense cirrus shield has overspread the region so we have increased
cloud cover to overcast for the rest of the night.
&&
.Short Term (Tonight through Thursday Night)...
Issued at 320 PM EST Wed Jan 9 2013
The weak tail end of a cold front passing mostly over southern
Indiana, northern KY, and locations northeast was located just south
of the Ohio River as of 1945Z. To the southeast of the front, a
thick deck of mid level clouds exists. However, this deck is making
steady progress eastward. Expect skies to go only partly cloudy for
a good portion of this evening before thick, low clouds start to
creep back in from the south after midnight.
After midnight a warm front will approach from the south as part of
a strengthening low pressure system over the OK/TX region. As this
weather system moves northeast to the western Great Lakes by Friday
morning, it will bring us 2 notable rounds of showers/isld storms
late tonight through Friday morning. The first round of elevated
showers/isld storms will come just after midnight tonight and
through tomorrow afternoon as the warm front lifts north through the
area. 6Z/12Z models have been slower with the arrival of these
rains so trended POPs back in time accordingly. We should see a
broad area of light rains slowly move north through the area for
much of Thurs. Any t-storms would likely be elevated north of the
warm front. However, some of the higher res model data suggests a
few scattered cellular structures during the late afternoon/evening
hours Thurs. Still these cells should be of little to no
consequence as morning clouds/rains will rob most areas of heating/
instability. The best chance for any scattered t-storms redeveloping
late Thurs afternoon/evening in the warm sector would be over south
central KY. Total QPF from this first wave of rainfall would be
under a half inch over most locations with areas along and west of
I-65 receiving the most rainfall.
The second wave of rains/isld t-storms will be late Thurs night into
Friday morning with the passage of a cold front. Before then, we
may continue to see scattered rains across the area Thurs evening.
The cold front looks to bring a solid line of rains with embedded
thunder through the area as it will be accompanied by a strong LLJ
(60-70 kts @ h85) and upper level jet support as the potent upper
trough passes just to our northwest. Friday morning would be our
best chance to see some strong to possibly marginally severe storms
due to such a strong LLJ passing through the area. A decent low
level inversion should keep most of the strongest winds aloft.
Still would not be surprise to see 35-50 mph winds mixing down
inside and outside of convection Friday morning. Small hail may
also be possible, but gusty winds and brief heavy rainfall would be
the main threats if any from storms Friday morning.
As far as temps go, they will be tricky over the next 36 hrs as
multiple frontal boundaries push through the area. Lows tonight
will range from the lower 30s over southern Indiana to mid and upper
40s over south central KY as a left over boundary stalls over the
region. Tomorrow expect highs ranging from the upper 40s north to
mid 60s south as we get a warm surge during the afternoon hours.
Thurs night, we`ll likely see a decrease in temps during the evening
hours with lows being reached just after midnight. A warm surge
will occur just ahead of cold front passage Friday morning allowing
temps to warm near dawn. Lows Thurs night should be in the upper
40s to around 60.
.Long Term (Friday through Wednesday)...
Issued at 305 PM EST Wed Jan 9 2013
...Wet and Unsettled Pattern Will Continue...
A building ridge off the Atlantic Coast and a digging western trough
will put the lower half of the Mississippi River Valley and the
entire Ohio River Valley under strong southwest flow aloft. This
will pump in plenty of moisture via an atmospheric river from the
Gulf, and set the stage for a very wet and active long term period.
The cold front associated with our first low pressure system
Thursday night will be entering our western forecast area around
daybreak Friday. Guidance continues to indicate instability will
decrease Thursday night into Friday morning, with some elevated
instability remaining. With the frontal passage at a diurnally
unfavorable time of day, the scenario projected by guidance is
reasonable. So, surfaced-based severe weather is looking less
likely. Surface-based instability will increase a bit through the
day Friday, as high temperatures warm well above normal into the low
and mid 60s. However, shear and large-scale forcing will decrease.
So, will continue with small hail and isolated strong wind gusts
being the main threats.
As this system departs Friday, it will leave behind a stalled
frontal boundary to our northwest that will not move much through
the weekend. Multiple shortwaves will ride over this boundary in
southwest flow aloft, with the first wave of rainfall expected
Saturday afternoon into Sunday. This band of rain should set up
across our northwestern forecast area for the overnight hours. The
rain will diminish a bit Sunday. However, another wave is expected
Sunday afternoon and evening, with yet another wave Sunday night
into Monday. With each wave, the southwest-northeast oriented
rainfall band will slowly track southeast.
Very warm temperatures and near record PWAT for this time
of year will be ushered in from the Gulf, with very high sub-cloud
layer relative humidity and warm cloud depth values in the 10-12Kft
range expected. This sets the stage for high precipitation
efficiency. Area average accumulations of 2-3 inches will be common
from Friday night through the day Monday, with locally higher
amounts possible. With this rain falling on wet ground provided by
the Wednesday and Thursday night/Friday systems, there could be some
areal flooding and rising rivers. Please see the hydrology section
below for more details on river impacts.
The surface front will sag southeast Sunday night, with some cooler
air filtering into our northern forecast area. Probabilistic and
plume data depict a small chance of some mixed precip on the back
side of the system. So, could see some mixed precip late Sunday
night through Monday morning before the system/deep moisture
departs. At this time, do not believe this will cause much of an
impact given the warm ground of late. Will monitor the thermal
profile and deep moisture over the next few model cycles.
As for temperatures, highs Saturday will reach the mid and upper
60s, with a cooling trend expected into Monday as the front slowly
pushes southeast. Highs Monday will range from the mid 30s in the
northwest to around 50 in the southeast. Low temperatures will show
a similar trend, with 40s and 50s Saturday night giving way to 20s
and 30s Monday night.
Guidance differs on the arrival of the next system, but ensemble
data suggests another round of precip Tuesday through Tuesday night.
With the surface boundary projected to be southeast of the forecast
area, cooler air in place across the forecast area, and steady
northeast surface winds, we could see another mixed precip event.
Confidence is not high on the overall thermal profile and placement
of precip, given the differences in model solutions, but ensemble
probabilities suggest a chance of mixed precip. Will continue to
monitor run-to-run model solutions for this system as well. It does
appear the system will exit the area Wednesday, with dry conditions
to follow. High temperatures Tuesday appear to range from mid 30s to
mid 40s, with highs a couple degrees cooler Wednesday. Overnight
lows will trend cooler as well, with generally mid 20s to low 30s
possible by Wednesday night.
&&
.Aviation (00Z TAF Issuance)...
Issued at 630 PM EST Wed Jan 9 2013
Flying conditions will deteriorate significantly during this TAF
period. A weakening upper level disturbance moving from Texas to
Missouri will pull a large area of rain northeastward along with
it. Rain will move into the BWG area after midnight tonight and
make it to the northern TAF sites by morning. The rain will then
continue through midday with low ceilings and MVFR visibilities
(possibly IFR at BWG).
During the afternoon hours a warm front will pass from south to
north across Kentucky, which will allow the rain to become more
scattered and will allow ceilings to rise a bit, though probably
stay MVFR.
Winds will gradually shift from northeast tonight to the east
tomorrow morning and to the southeast tomorrow afternoon as the warm
front approaches and passes on through.
&&
.Hydrology...
A series of winter storms are forecast to move across the Ohio
Valley starting early Thursday morning. The first wave is expected
to deliver up to an inch of rainfall. However, soils are not frozen
and still fairly dry, especially in western Kentucky, so little
runoff is expected.
The more important storm system is expected this weekend when a
series of waves along with copious amounts of moisture will make for
a couple of wet days. Over the entire 3 days, areas should average
between 2 and 3 inches of rain with the heavier amounts over
southern Kentucky. This rain will cause streams to rise and some
near bankfull crests could occur. However, since the rain will be
spread out over several days and current streamflows are not
elevated, any flooding that may occur should be minor. The best
chance for flooding will be in the western portion of the Green
River Basin.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........13
Short Term.......AMS
Long Term........MJP
Aviation.........13
Hydrology........CMC
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
344 PM CST TUE JAN 8 2013
.SHORT TERM...
ISSUED AT 335 PM CST TUE JAN 8 2013
(TONIGHT)
A NRN STREAM SHORTWAVE WILL PASS NORTH OF THE AREA TONIGHT ALTHOUGH
IT WILL DRAG A WEAK CDFNT THROUGH THE CWA. ATTM NO PCPN IS EXPECTED
WITH THE CDFNT DUE TO THE INITIALLY DRY AIR MASS PER 12Z SGF
SOUNDING...LIMITED MOISTURE ACCOMPANYING THE NRN STREAM
SHORTWAVE...AND UNFAVORABLE DYNAMICS THIS FAR SOUTH OF THE VORT MAX.
THE PRIMARY EFFECT OF THE CDFNT WILL BE TO CAUSE WINDS TO VEER FM
SLY TO WLY OVERNIGHT. ALTHOUGH THE NAM/SREF SEEM TO BE OVERDOING THE
LOW LEVEL MOISTURE BASED ON THE LATEST OBS...MID-LEVEL MOISTURE
SHOULD BEGIN MOVING NWD TONIGHT IN RESPONSE TO A STRONG LOW PRESSURE
SYSTEM IN NRN MEXICO/SRN TX. SOME PCPN HAS ALREADY DVLPD OVER AR
AHEAD OF THE SRN SYSTEM AND IT IS POSSIBLE THAT THERE MAY BE ENOUGH
LIFT TO SUPPORT A FEW SPRINKLES ACROSS THE SRN CWA.
KANOFSKY
&&
.LONG TERM...
ISSUED AT 335 PM CST TUE JAN 8 2013
(WEDNESDAY THROUGH TUESDAY)
A GOOD POTENTIAL FOR SIGNIFICANT QPF IS EXPECTED FOR WED NGT THROUGH
THU NGT AS THE UPPER LEVEL LOW OVER OLD MEXICO MOVES SLOWLY NEWD
THROUGH THE SRN PLAINS WED AND WED NGT...THEN EVENTUALLY MOVES
NEWD THROUGH MO THU NGT. PREFER THE MORE NRN SOLUTION OF THE 500
MB LOW TRACK OF THE NAM AND ECMWF MODELS OVER THE GFS. MOST OF THE
PRECIPITATION SHOULD REMAIN S OF OUR FORECAST AREA ON WED...BUT
THEN SPREAD NEWD INTO MUCH OF THE REGION WED NGT AS A STRONG SLY
LOW LEVEL JET BRINGS LOW LEVEL MOISTURE NWD INTO MUCH OF MO AND
SRN IL. SHOWERS AND AT LEAST A FEW THUNDERSTORMS CAN BE EXPECTED
ON THU AS A WEAK SFC LOW AND WARM FRONT LIFT NWD INTO SRN
MO...WITH INCREASING UPPER LEVEL DIVERGENCE OVER OUR AREA AHEAD OF
THE APPROACHING UPPER LEVEL TROUGH. MUCH OF THE PRECIPITATION
SHOULD SHIFT E OF OUR AREA BY LATE THU NGT AS THE UPPER LEVEL LOW
OPENS UP AND WEAKENS AS IT MOVES TOWARDS THE GREAT LAKES REGION.
UNSEASONABLY WARM WEATHER WILL CONTINUE ON FRI WITH S-SWLY LOW
LEVEL WINDS ALONG WITH A CLEARING SKY. BOTH THE NAM AND ECMWF
MODELS FORECAST 850 MB TEMPERATURES OF AROUND 12 DEGREES C BY 00Z
SAT ACROSS MUCH OF OUR AREA. WILL LIKELY HAVE HIGHS IN THE LOWER
60S ACROSS MOST OF THE AREA ON FRI. SAT WILL BE THE LAST DAY OF
ABOVE NORMAL TEMPERATURES AS A COLD FRONT DROPS SOUTHEASTWARD
THROUGH OUR FORECAST AREA LATE FRI NGT AND SAT. ALTHOUGH THE FRONT
SHOULD MOVE THROUGH DRY THE MODELS DO GENERATE POST FRONTAL
PRECIPITATION SAT NGT AS A WEAK SFC WAVE MOVES ALONG THE FRONT
WITH AN APPROACHING POSITIVELY TILTED UPPER LEVEL TROUGH WELL WEST
OF THE AREA. LOOKS LIKE MOST OF THE PRECIPITATION WILL BE ACROSS
SERN MO AND SWRN IL IN THE WARMER AIR...BUT COULD NOT RULE OUT A
LITTLE LIGHT SNOW N AND W OF STL IN THE COLDER AIR. THE POTENTIAL
FOR AT LEAST LIGHT PRECIPITATION MAY CONTINUE ACROSS SERN MO AND
SWRN IL UNTIL MON WHEN A STRONG SFC RIDGE OVER THE NRN PLAINS
FINALLY BUILDS SEWD INTO MO WITH THE COLD FRONT SHIFTING WELL SE
OF OUR AREA. MUCH COLDER...MORE SEASONAL TEMPERATURES CAN BE
EXPECTED SUN THROUGH TUE.
GKS
&&
.AVIATION...
ISSUED AT 1124 AM CST TUE JAN 8 2013
VFR THROUGH THE PD WITH MID AND HIGH LEVEL CLOUDS. INITIALLY SLY
WINDS WILL VEER SWLY AHEAD OF A WEAK COLD FRONT THEN BECOME WLY
AFTER FROPA. GENERALLY FOLLOWED THE RAP/ECMWF FOR CIG TRENDS
SINCE NAM/SREF APPEAR TO BE TOO MOIST AT LOW LEVELS. IF SFC WINDS
DECOUPLE TONIGHT THEN LLWS MAY BECOME A CONCERN BETWEEN 03-09Z
BASED ON RAP FCSTS OF WINDS ALOFT.
SPECIFICS FOR KSTL...VFR THROUGH THE PD WITH MID AND HIGH LEVEL
CLOUDS. INITIALLY SLY WINDS WILL VEER SWLY AHEAD OF A WEAK COLD
FRONT THEN BECOME WLY AFTER FROPA.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1138 AM CST TUE JAN 8 2013
.SHORT TERM...
ISSUED AT 356 AM CST TUE JAN 8 2013
(TODAY)
SOUTHERLY FLOW TO PERSIST ACROSS THE REGION TODAY AHEAD OF A WEAK
COLD FRONT. IN THE MEANTIME...HIGH THIN CLOUDS TO SLIDE NORTHEAST
ACROSS AREA...BUT DESPITE THE CLOUDS...WILL SEE TEMPS WARM UP INTO
THE UPPER 40S TO MID 50S WITH THE WARMEST TEMPERATURES OVER CENTRAL
MO.
BYRD
&&
.LONG TERM...
ISSUED AT 356 AM CST TUE JAN 8 2013
(TUESDAY NIGHT - WEDNESDAY)
THE WARMTH WILL PERSIST THRU THE PERIOD AS COLD AIR REMAINS LOCKED
NORTH OF THE POLAR JET STREAM ALONG THE CANADIAN BORDER. SPLIT FLOW
STHRN STREAM CUT OFF LOW CONTINUES E ACROSS NTHRN MEXICO. DECENT
SHORT WAVE WILL PASS NORTH OF THE AREA TUESDAY NIGHT. THIS WILL
ALLOW A WEAK COLD FRONT TO DROP INTO THE CWA OVERNIGHT. THE BNDRY
DOESN`T HAVE MUCH PUSH TO IT SO IT STALLS AND WASHES OUT WEDNESDAY
MORNING. THE ATMOSPHERE IS FAIRLY DRY SO THE SHORT WAVE AND ASSOC
FRONT SHOULDN/T PRODUCE MUCH MORE THAN ENHANCED MID/HIGH LEVEL
CLOUDINESS. HIGH PRESSURE QUICKLY MOVES EAST ON WEDNESDAY. WINDS
BECOME EASTERLY IN THE WAKE OF THE HIGH AND IN ADVANCE OF THE STORM
SYSTEM DUE IN FOR WEDNESDAY NIGHT. THE CUT-OFF LOW MAKES A NE TURN
AND CROSSES THE RIO GRNADE INTO TX LATE IN THE PERIOD.
MOS WAS IN DECENT AGREEMENT FOR TUESDAY NIGHT SO WENT WITH A BLEND.
WENT ABOVE THE WARMER MAV ACROSS THE NTRHN CWA WEDNESDAY. FOR THE
SOUTH...USED A BLEND AS THE GUIDANCE WAS NOT IN VERY GOOD AGREEMENT.
SOME PLACES THE MAV WAS WARMER...LIKE KFAM...WHILE OTHERS IT WAS THE
MET...KSAR AND KSLO. THIS IS DUE TO THE NAMS FASTER SOLUTION AND
QUICKER ONSET OF PRECIP ACROSS THE SOUTH.
(WEDNESDAY NIGHT - THURSDAY NIGHT)
UPPER LOW MOVES FROM TX WEDNESDAY NIGHT AND TRANSITIONS TO AN OPEN
WAVE ACROSS THE GRT LKS BY FRIDAY MORNING. THE MODELS HAVE COME INTO
BETTER AGREEMENT IN THE PAST 24 HRS AS TO LOCATION. THE NAM SOLUTION
WRT THE 500MB LOW MOVING FURTHER EAST. THIS GROUP OF
SOLUTIONS...NAM/SREF/LOCAL WRF...ARE CONSIDERABLY FASTER THAN THE
ECMWF/GEM WHILE GFS BASICALLY SPLITS THE DIFFERENCE. THIS FEATURE IS
AGAIN LIKELY NOT BEING SAMPLED WELL DUE TO HOW FAR INTO MEXICO IT
HAS PROGRESSED. THE ENERGY COMING INTO THE NW COAST OBVIOUSLY ISN/T
BEING SAMPLED WELL EITHER. UNTIL THEY ARE...THESE DIFFERENCES ARE
LIKELY NOT TO BE RESOLVED. DO NOT HAVE A STRONG OPINION ON EITHER
SCENARIO...BUT IF HAD TO MAKE A CHOICE...WOULD GO WITH THE GFS AS A
GOOD COMPROMISE. THE ECMWF SEEMS TOO SLOW OF AN OUTLIER ATM. THAT
BEING SAID...I INHERITED A FASTER ONSET TO PRECIP THAN LAST NIGHT.
CERTAINLY CAN/T RULE OUT THAT SCENARIO...SO DIDN/T CHANGE MUCH WITH
REGARDS TO TIMING. I DID BUMP POPS UP FOR THE MIDNIGHT TO NOON
THURSDAY TIME FRAME. DUE TO HOW FAR SOUTH THIS SYSTEM IS FCST TO
DIG...IT IS EXPECTED TO PULL A REMARKABLE AMOUNT OF MOISTURE NORTH
WITH IT. 850 MB DPS OF NEAR 10C AS FAR NORTH AS KSTL. THIS EQUATES
TO PWATS OF 1-1.5 INCHES...WHICH IS 2+ SD ABOVE CLIMO. THUNDER STILL
LOOKS POSSIBLE WITH THE AREAS ALONG AND S OF I44 IN MO AND I70 IN IL
WITH THE BEST CHANCES. THESE SAME AREAS MAY SEE 1-2 INCHES OF
PRECIP. DEPENDING ON THE EXACT TRACK OF THE LOW AND THE EVOLUTION OF
THE DRY SLOT...A PORTION OF THE CNTRL CWA MAY SEE SOME SUN...MIX AND
REALLY WARM UP. TRIED TO CONVEY THIS WITH LOWER 60S SOUTH OF I70.
PRECIP SHOULD COME TO AN END THURSDAY EVENING. THE WARM CONVEYOR
AHEAD OF THE FRONT SHOULD PUSH EAST WHILE PRECIP TIED TO THE UPPER
LOW LIFTS NE.
(FRIDAY - MONDAY)
THE REGION REMAINS IN SPLIT FOR FOR ONE MORE DAY. AS THE LOW PULLS
AWAY...THE CWA IS LEFT IN SW FLOW AT THE SFC AND ALOFT. FCST 850
TEMPS ARE FAIRLY REMARKABLE AT +10 TO +14 FRIDAY AFTN. IF WE ONLY
MIX TO 925MB...CLIMO INDICATES HIGH OF AT LEAST 60-65. THE GFS HINTS
THAT NW PORTIONS OF THE CWA MAY MIX TO GREATER THAN 900 MB. IF THIS
OCCURS...THEN MAX TEMPS MAY REACH 65-70. NOT READY TO JUMP ON THAT
YET...BUT IS CERTAINLY SOMETHING TO WATCH IN THE COMING DAYS AS
THOSE TEMPS COME CLOSE IF NOT EXCEED EXISTING RECORDS FOR THE DATE.
THE ENERGY THAT PUSHED THE CLOSED LOW INTO OUR AREA IS FCST TO
EFFECTIVELY PHASE THE JET STREAMS. THIS WILL ALLOW A STRONG COLD
FRONT INTO THE REGION OVER THE WKND. THE ARCTIC FRONT IS STILL ON
TRACK TO PLOW THRU THE AREA SATURDAY. THE FRONT STALLS JUST TO OUR
SE AS A WAVE OF LOW PRESSURE SLIDES NE ALONG THE FRONT SATURDAY AFTN
AND SATURDAY NIGHT. PRECIP SHOULD OVERSPREAD THE SERN HALF OF THE
CWA SATURDAY AFTN...CONTINUE SATURDAY NIGHT AND THEN END BY SUNDAY
MORNING. ATTM IT APPEARS THAT THE MAJORITY OF THE PRECIP WILL BE
LIQUID...BUT CAN/T RULE OUT WNTRY PRECIP ON THE WRN FRINGE OF THE
PRECIP SHIELD.
THE BNDRY DOESN/T SEEM TO MOVE MUCH THRU THE BEGINNING OF THE WEEK.
THE GFS AND ECMWF HAVE RIPPLES OF LOW PRESSURE THAT CONTINUE TO MOVE
ALONG THE FRONT PRODUCING WAVES OF PRECIP. TIMING AND PLACEMENT OF
THESE PRECIP EVENTS VARY...BUT THE PATTERN BEARS WATCHING.
THE ARCTIC FRONT CERTAINLY APPEARS TO HAVE INITIATED A PATTERN SHIFT
AS THE MEAN LONG WAVE TROUGH SLOWLY WORKS ACROSS THE CONUS THRU THE
WEEK KEEPING THINGS SEASONABLY COOL. THE ECMWF HINTS AT SPLIT FLOW
AGAIN FOR NEXT WEEK WITH A CUT OFF LOW OFF THE CA COAST BY MONDAY.
THANKFULLY THERE ARE SEVERAL DAYS TO WATCH THE WKND WX AND BEYOND.
MILLER
&&
.AVIATION...
ISSUED AT 1124 AM CST TUE JAN 8 2013
VFR THROUGH THE PD WITH MID AND HIGH LEVEL CLOUDS. INITIALLY SLY
WINDS WILL VEER SWLY AHEAD OF A WEAK COLD FRONT THEN BECOME WLY
AFTER FROPA. GENERALLY FOLLOWED THE RAP/ECMWF FOR CIG TRENDS
SINCE NAM/SREF APPEAR TO BE TOO MOIST AT LOW LEVELS. IF SFC WINDS
DECOUPLE TONIGHT THEN LLWS MAY BECOME A CONCERN BETWEEN 03-09Z
BASED ON RAP FCSTS OF WINDS ALOFT.
SPECIFICS FOR KSTL...VFR THROUGH THE PD WITH MID AND HIGH LEVEL
CLOUDS. INITIALLY SLY WINDS WILL VEER SWLY AHEAD OF A WEAK COLD
FRONT THEN BECOME WLY AFTER FROPA.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1129 AM CST TUE JAN 8 2013
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
In the short term, concerns are focused on temperatures along with
rainfall potential Wednesday night into Thursday. Early this morning,
a large upper level low continued to spin over northern Mexico as a
progressive upper trough crosses the Northern Plains. Due to an
enhanced area of cirrus moving across the region, temperatures have
remained in the 30s in most locations.
Today: Upper troughing in the Northern Plains will establish weak
surface troughing across portions of east central Kansas through
northwestern Missouri. Winds ahead of this surface trough will again
become breezy by afternoon, with abnormally warm 950:850 temperatures
supporting temperatures into the 50s in many areas. Again, have
followed short term RAP guidance for temperatures this afternoon
which did an excellent job on Monday. The warmest temperatures may
pool just ahead of this surface trough where readings could spike
into the middle 50s.
Tonight: The weak surface trough will move into the region washing
out as it does so. A bit less cirrus may be possible given the
northwesterly upper level flow. The resultant temperatures will fall
into the upper 20s in most locations.
Wednesday: The upper level low over northern Mexico will finally
become dislodged as troughing enters the Pacific Northwest. Locally,
an elongated west to east ridge of high pressure will remain over the
area throughout the daytime hours, keeping winds light and variable.
Temperatures, given the weak boundary and low level flow, will not be
quite as warm as on Tuesday but should still climb near 50.
Wednesday night: The upper level low will quickly begin to surge
north by Wednesday evening with strong low-level moisture advection
headed into the area. Showers and even embedded thunderstorms will
overspread the area through the overnight hours. Models in reasonable
agreement (less the NAM) that rain will reach the Interstate 70
corridor by midnight and northern Missouri by daybreak.
Thursday: Tricky forecast as models indicate the deep upper low will
lift across the CWA during the daytime hours. Rain should quickly
lift northward in the morning, replaced with low cloud cover and
periods of showers/drizzle. Temperatures will be rather difficult and
highly dependent on the track of surface low pressure and surge of
warm air ahead of the surface low. Model guidance suggests a weak
surface low tracking north along with the upper low through eastern
Kansas by Thursday afternoon. NAM is the most aggressive bringing
near 60 degree readings into the CWA, but it is also the deepest and
most progressive solution of all guidance. Prefer the weaker
solutions of the GFS/SREF which still bring low 50s by the late
afternoon hours.
Dux
Medium Range (Friday through Monday)...
The medium range should start out very warm especially for the
climatologically coldest week of the year for Kansas City (January
10-17). With 850mb temps between 12C-14C, if we can mix out enough,
temperatures could easily range into the mid 50s to mid 60s.
However, those warm temperatures will be short-lived as a cold front
is forced into the forecast area Friday night in association with a
broad and deep upper level trough that will be traversing the
Rockies. This frontal passage looks to be dry as models are in good
agreement that the best moisture transport is south and east of the
forecast area. As such have lowered chance POPs inherited by the
initialization to silent slight chance POPs for Saturday. The main
effect of this cold front will be the marked change in temperatures.
High temperatures across the CWA Saturday will experience a 20
degree range from near 30 across northern Missouri where cold air
advection will be ongoing by day break...to near 50 across central
Missouri where cold air doesn`t begin to advect in until later in
the day. The upper level trough moves through the area on Sunday as
high pressure builds in at the surface with highs in the mid 20s to
lower 30s. Surface high pressure strengths over the area on Monday
and with abundant sunshine highs will return to near normal for the
coldest climatological week of the year with highs in the 30s.
73
&&
.AVIATION...
For the 18Z TAFs...VFR conditions will persist. South-southwest
winds will veer to the west this evening with the passage of a weak
surface trough. Winds will continue to veer to the north Wednesday
morning in response to the cut-off low approaching from the south.
MJ
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
535 AM CST TUE JAN 8 2013
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
In the short term, concerns are focused on temperatures along with
rainfall potential Wednesday night into Thursday. Early this morning,
a large upper level low continued to spin over northern Mexico as a
progressive upper trough crosses the Northern Plains. Due to an
enhanced area of cirrus moving across the region, temperatures have
remained in the 30s in most locations.
Today: Upper troughing in the Northern Plains will establish weak
surface troughing across portions of east central Kansas through
northwestern Missouri. Winds ahead of this surface trough will again
become breezy by afternoon, with abnormally warm 950:850 temperatures
supporting temperatures into the 50s in many areas. Again, have
followed short term RAP guidance for temperatures this afternoon
which did an excellent job on Monday. The warmest temperatures may
pool just ahead of this surface trough where readings could spike
into the middle 50s.
Tonight: The weak surface trough will move into the region washing
out as it does so. A bit less cirrus may be possible given the
northwesterly upper level flow. The resultant temperatures will fall
into the upper 20s in most locations.
Wednesday: The upper level low over northern Mexico will finally
become dislodged as troughing enters the Pacific Northwest. Locally,
an elongated west to east ridge of high pressure will remain over the
area throughout the daytime hours, keeping winds light and variable.
Temperatures, given the weak boundary and low level flow, will not be
quite as warm as on Tuesday but should still climb near 50.
Wednesday night: The upper level low will quickly begin to surge
north by Wednesday evening with strong low-level moisture advection
headed into the area. Showers and even embedded thunderstorms will
overspread the area through the overnight hours. Models in reasonable
agreement (less the NAM) that rain will reach the Interstate 70
corridor by midnight and northern Missouri by daybreak.
Thursday: Tricky forecast as models indicate the deep upper low will
lift across the CWA during the daytime hours. Rain should quickly
lift northward in the morning, replaced with low cloud cover and
periods of showers/drizzle. Temperatures will be rather difficult and
highly dependent on the track of surface low pressure and surge of
warm air ahead of the surface low. Model guidance suggests a weak
surface low tracking north along with the upper low through eastern
Kansas by Thursday afternoon. NAM is the most aggressive bringing
near 60 degree readings into the CWA, but it is also the deepest and
most progressive solution of all guidance. Prefer the weaker
solutions of the GFS/SREF which still bring low 50s by the late
afternoon hours.
Dux
Medium Range (Friday through Monday)...
The medium range should start out very warm especially for the
climatologically coldest week of the year for Kansas City (January
10-17). With 850mb temps between 12C-14C, if we can mix out enough,
temperatures could easily range into the mid 50s to mid 60s.
However, those warm temperatures will be short-lived as a cold front
is forced into the forecast area Friday night in association with a
broad and deep upper level trough that will be traversing the
Rockies. This frontal passage looks to be dry as models are in good
agreement that the best moisture transport is south and east of the
forecast area. As such have lowered chance POPs inherited by the
initialization to silent slight chance POPs for Saturday. The main
effect of this cold front will be the marked change in temperatures.
High temperatures across the CWA Saturday will experience a 20
degree range from near 30 across northern Missouri where cold air
advection will be ongoing by day break...to near 50 across central
Missouri where cold air doesn`t begin to advect in until later in
the day. The upper level trough moves through the area on Sunday as
high pressure builds in at the surface with highs in the mid 20s to
lower 30s. Surface high pressure strengths over the area on Monday
and with abundant sunshine highs will return to near normal for the
coldest climatological week of the year with highs in the 30s.
73
&&
.AVIATION...
For the 12Z TAFs...conditions will remain VFR through the TAF period
with just cirrus expected through the day before clearing skies
tonight. Winds out of the south this morning around 10kts will veer
to the southwest this afternoon. A weak surface trough will move
through the terminals tonight veering winds to the west at MCI while
winds and MKC and STJ become light and variable.
73
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
336 AM CST Tue Jan 8 2013
.DISCUSSION...
In the short term, concerns are focused on temperatures along with
rainfall potential Wednesday night into Thursday. Early this morning,
a large upper level low continued to spin over northern Mexico as a
progressive upper trough crosses the Northern Plains. Due to an
enhanced area of cirrus moving across the region, temperatures have
remained in the 30s in most locations.
Today: Upper troughing in the Northern Plains will establish weak
surface troughing across portions of east central Kansas through
northwestern Missouri. Winds ahead of this surface trough will again
become breezy by afternoon, with abnormally warm 950:850 temperatures
supporting temperatures into the 50s in many areas. Again, have
followed short term RAP guidance for temperatures this afternoon
which did an excellent job on Monday. The warmest temperatures may
pool just ahead of this surface trough where readings could spike
into the middle 50s.
Tonight: The weak surface trough will move into the region washing
out as it does so. A bit less cirrus may be possible given the
northwesterly upper level flow. The resultant temperatures will fall
into the upper 20s in most locations.
Wednesday: The upper level low over northern Mexico will finally
become dislodged as troughing enters the Pacific Northwest. Locally,
an elongated west to east ridge of high pressure will remain over the
area throughout the daytime hours, keeping winds light and variable.
Temperatures, given the weak boundary and low level flow, will not be
quite as warm as on Tuesday but should still climb near 50.
Wednesday night: The upper level low will quickly begin to surge
north by Wednesday evening with strong low-level moisture advection
headed into the area. Showers and even embedded thunderstorms will
overspread the area through the overnight hours. Models in reasonable
agreement (less the NAM) that rain will reach the Interstate 70
corridor by midnight and northern Missouri by daybreak.
Thursday: Tricky forecast as models indicate the deep upper low will
lift across the CWA during the daytime hours. Rain should quickly
lift northward in the morning, replaced with low cloud cover and
periods of showers/drizzle. Temperatures will be rather difficult and
highly dependent on the track of surface low pressure and surge of
warm air ahead of the surface low. Model guidance suggests a weak
surface low tracking north along with the upper low through eastern
Kansas by Thursday afternoon. NAM is the most aggressive bringing near
60 degree readings into the CWA, but it is also the deepest and most
progressive solution of all guidance. Prefer the weaker solutions of
the GFS/SREF which still bring low 50s by the late afternoon hours.
Dux
Medium Range (Friday through Monday)...
The medium range should start out very warm especially for the
climatologically coldest week of the year for Kansas City (January
10-17). With 850mb temps between 12C-14C, if we can mix out enough,
temperatures could easily range into the mid 50s to mid 60s.
However, those warm temperatures will be short-lived as a cold front
is forced into the forecast area Friday night in association with a
broad and deep upper level trough that will be traversing the
Rockies. This frontal passage looks to be dry as models are in good
agreement that the best moisture transport is south and east of the
forecast area. As such have lowered chance POPs inherited by the
initialization to silent slight chance POPs for Saturday. The main
effect of this cold front will be the marked change in temperatures.
High temperatures across the CWA Saturday will experience a 20
degree range from near 30 across northern Missouri where cold air
advection will be ongoing by day break...to near 50 across central
Missouri where cold air doesn`t begin to advect in until later in
the day. The upper level trough moves through the area on Sunday as
high pressure builds in at the surface with highs in the mid 20s to
lower 30s. Surface high pressure strengths over the area on Monday
and with abundant sunshine highs will return to near normal for the
coldest climatological week of the year with highs in the 30s.
73
&&
.AVIATION...
No changes for the 06Z TAFs.
Other than periods of broken cirrus, TAFs will feature rather benign
conditions over the next 24 hours. Winds will remain 8-10 knots at
MCI, but should decouple at MKC/STJ. With the eastern edge of a
modest nocturnal jet brushing across STJ overnight, significant low
level turning (40-50 degrees) and speed shear (30-35 knots) has
resulted in the introduction of LLWS for STJ from midnight through
late morning when sufficient mixing depth will eliminate the abrupt
inversion. Surface winds should increase to 10-14 knots with a
gradual veering toward the southwest during the day, and then toward
the west-southwest during the evening.
Bookbinder
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1108 PM CST MON JAN 7 2013
.AVIATION...
06Z TAFS FOR KOMA...KLNK...KOFK.
FOG HAD DEVELOPED OVER PARTS OF THE AREA...MAINLY WHERE THERE WAS
MELTING DURING THE DAY AND SIGNIFICANT SNOW COVER REMAINED IN
PLACE. DID MAKE SOME ADJUSTMENTS TO THE TAFS FOR THE OVERNIGHT
HOURS AND INTO TUESDAY MORNING. SOME IFR VISIBILITIES WILL BE
POSSIBLE...ESPECIALLY FROM BETWEEN 09Z AND 14Z. WILL CONTINUE TO
MONITOR FOR DENSE FOG DEVELOPMENT AND AMEND AS NEEDED. LIGHT WINDS
TONIGHT WILL BECOME SOUTHERLY TUESDAY MORNING THEN SHIFT TO WEST
OR SOUTHWEST IN THE AFTERNOON.
MILLER
&&
.PREV DISCUSSION... /ISSUED 1013 PM CST MON JAN 7 2013/
UPDATE...
PUBLIC FORECASTS WERE AMENDED TO INCLUDE SOME MENTION OF DENSE
FOG OVER AREAS THAT HAVE SNOW COVER. ALSO DECREASED LOWS A BIT IN
SOME LOCATIONS.
MILLER
&&
PREV DISCUSSION... /ISSUED 234 PM CST MON JAN 7 2013/
SHORT TERM...TONIGHT THROUGH THURSDAY.
MAIN FORECAST CONCERNS WILL DEAL WITH TEMPERATURES AND TIMING OF
SYSTEM MOVING OUT OF THE SOUTHERN PLAINS WEDNESDAY NIGHT INTO
THURSDAY.
DESPITE THICK CIRRUS LAYER ACROSS PARTS OF THE AREA AND LIGHT
SURFACE WINDS ALONG A WEAK TROUGH INTO EAST CENTRAL NEBRASKA...
TEMPERATURES HAVE MANAGED TO CLIMB INTO THE MID AND UPPER 30S IN
SNOW COVERED PORTION OF THE CWA WITH MID 40S TO LOWER 50S IN SNOW
FREE PARTS OF SOUTHEAST NEBRASKA AND SOUTHWEST IOWA THIS AFTERNOON.
INITIAL CONCERN FOR TONIGHT WILL BE POTENTIAL FOG DEVELOPMENT IN
THE SNOW AREAS WHERE SOME MELTING TODAY HAS ADDED MOISTURE TO THE
BOUNDARY LAYER. SHORT RANGE RAP HINTS AT DEVELOPMENT AFTER 06Z IN
AREA WHERE MENTION OF PATCHY FOG IS ALREADY IN CURRENT FORECAST.
FOR TUESDAY AND WEDNESDAY QUESTION WILL BE HOW WARM WILL
TEMPERATURES BE ABLE TO REACH. BASED ON TODAYS READINGS CLIMBING
TO AROUND 50 IN THE SOUTHEAST PART OF THE CWA...HAVE WENT A
WARMER THAN GUIDANCE IN THE SNOW FREE AREAS WITH SNOW FIELD STILL
EXPECTED TO KEEP TEMPERATURES TO THE NORTH CLOSE TO GUIDANCE.
TIMING ISSUES AMONG THE MODELS STILL IN PLAY FOR WEDNESDAY NIGHT
AND THURSDAY WITH NAM THE FASTEST AND LEAST REGARDED AT THIS TIME
FRAME. GFS AND EURO HAVE BETTER AGREEMENT BUT EURO REMAINS SLOWER
IN MOVING THE SYSTEM ACROSS THE AREA. FORECAST SOUNDINGS FOR
WEDNESDAY NIGHT SUGGEST TEMPERATURES SHOULD BE WARM ENOUGH ACROSS
THE SOUTH HALF OF THE AREA FOR PRECIP TO BE ALL LIQUID WITH
TEMPERATURES REMAINING ABOVE FREEZING ON THURSDAY ACROSS ALL THE
AREA AS RAIN CONTINUES.
FOBERT
LONG TERM...THURSDAY NIGHT THROUGH MONDAY.
THE GFS AND ECM ARE IN RELATIVELY GOOD AGREEMENT WITH REGARDS TO
LARGE SCALE IN THE EXTENDED PD. BOTH ALSO SUGGESTING LITTLE CHANGE
NEEDED TO GOING FCST.
HEADING INTO NEXT WEEKEND...MODELS ADVERTISE SHORTWAVE ENERGY OVER
IA QUICKLY LIFTING TO THE GREAT LAKES REGION LATE THURSDAY NIGHT.
MEANWHILE UPSTREAM...A DEEP LONGWAVE TROF IS PROGGED TO EXTEND FROM
CNTRL CANADA ALL THE WAY TO THE SWRN CONUS. ON FRIDAY AS THE WRN
TROF GRADUALLY MIGRATES EAST...INTENSE BAROCLINIC ZONE BEGINS
SWEEPING ACROSS THE NRN/CNTRL PLAINS WITH THE LEADING EDGE OF THE
BOUNDARY REACHING THE CWA BY EARLY AFTN. COMBINATION OF INCREASING
MOISTURE AND STOUT AGEOSTROPHIC LIFT ALONG DEEP FRONTOGENETIC LYR
SHOULD BE ENOUGH TO INDUCE LIGHT SNOW ACTIVITY DURING THE FROPA
FRIDAY NIGHT.
ON SATURDAY...APPEARS TO BE A SMALL CHANCE FOR LIGHT POST-FRONTAL
SNOW ACTIVITY PER THE ECM. 300-500MB QVEC CONVERGENCE IMPLYING LIFT
VIA DPVA WHEN POTENT OR MAX ROUNDS THE BASE OF THE WRN TROF AND
LIFTS ACROSS THE CNTRL PLAINS. ON THE OTHER HAND...GFS AND CMC BOTH
SUGGESTING THE DEEP CAA WILL BE ADEQUATE TO SUPPRESS ANY LIFT VIA
DPVA. WILL OPTED FOR TOKEN 20S JUST IN CASE ECM SOLUTION WOULD
VERIFY.
OTHERWISE...TEMPS WILL PLUMMET OVER THE PLAINS NEXT WEEKEND INTO
EARLY NEXT WEEK. EXPECT HIGHS SAT-MON WILL STRUGGLE TO REACH THE
LOWER/MID 20S.
DEE
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS OMAHA/VALLEY NE
1013 PM CST MON JAN 7 2013
.UPDATE...
PUBLIC FORECASTS WERE AMMENDED TO INCLUDE SOME MENTION OF DENSE
FOG OVER AREAS THAT HAVE SNOW COVER. ALSO DECREASED LOWS A BIT
IN SOME LOCATIONS.
MILLER
&&
.PREV DISCUSSION... /ISSUED 522 PM CST MON JAN 7 2013/
AVIATION...
00Z TAFS FOR KOMA...KLNK...KOFK.
WILL HAVE TO MONITOR FOR DEVELOPMENT OF STRATUS AND FOG TONIGHT.
DID MENTION SOME MVFR VISIBILITIES LATER TONIGHT BUT DID NOT WANT
TO GET TOO PESSIMISTIC. GFS MODEL DOES NOT DEVELOP FOG...WHILE
THE NAM DOES. GENERALLY FELT THE NAM LOW LEVEL MOISTURE WAS
OVERDONE BUT WILL MONITOR AND AMEND TAFS THROUGH THE EVENING AS
NEEDED.
MILLER
PREV DISCUSSION... /ISSUED 234 PM CST MON JAN 7 2013/
SHORT TERM...TONIGHT THROUGH THURSDAY.
MAIN FORECAST CONCERNS WILL DEAL WITH TEMPERATURES AND TIMING OF
SYSTEM MOVING OUT OF THE SOUTHERN PLAINS WEDNESDAY NIGHT INTO
THURSDAY.
DESPITE THICK CIRRUS LAYER ACROSS PARTS OF THE AREA AND LIGHT
SURFACE WINDS ALONG A WEAK TROUGH INTO EAST CENTRAL NEBRASKA...
TEMPERATURES HAVE MANAGED TO CLIMB INTO THE MID AND UPPER 30S IN
SNOW COVERED PORTION OF THE CWA WITH MID 40S TO LOWER 50S IN SNOW
FREE PARTS OF SOUTHEAST NEBRASKA AND SOUTHWEST IOWA THIS AFTERNOON.
INITIAL CONCERN FOR TONIGHT WILL BE POTENTIAL FOG DEVELOPMENT IN
THE SNOW AREAS WHERE SOME MELTING TODAY HAS ADDED MOISTURE TO THE
BOUNDARY LAYER. SHORT RANGE RAP HINTS AT DEVELOPMENT AFTER 06Z IN
AREA WHERE MENTION OF PATCHY FOG IS ALREADY IN CURRENT FORECAST.
FOR TUESDAY AND WEDNESDAY QUESTION WILL BE HOW WARM WILL
TEMPERATURES BE ABLE TO REACH. BASED ON TODAYS READINGS CLIMBING
TO AROUND 50 IN THE SOUTHEAST PART OF THE CWA...HAVE WENT A
WARMER THAN GUIDANCE IN THE SNOW FREE AREAS WITH SNOW FIELD STILL
EXPECTED TO KEEP TEMPERATURES TO THE NORTH CLOSE TO GUIDANCE.
TIMING ISSUES AMONG THE MODELS STILL IN PLAY FOR WEDNESDAY NIGHT
AND THURSDAY WITH NAM THE FASTEST AND LEAST REGARDED AT THIS TIME
FRAME. GFS AND EURO HAVE BETTER AGREEMENT BUT EURO REMAINS SLOWER
IN MOVING THE SYSTEM ACROSS THE AREA. FORECAST SOUNDINGS FOR
WEDNESDAY NIGHT SUGGEST TEMPERATURES SHOULD BE WARM ENOUGH ACROSS
THE SOUTH HALF OF THE AREA FOR PRECIP TO BE ALL LIQUID WITH
TEMPERATURES REMAINING ABOVE FREEZING ON THURSDAY ACROSS ALL THE
AREA AS RAIN CONTINUES.
FOBERT
LONG TERM...THURSDAY NIGHT THROUGH MONDAY.
THE GFS AND ECM ARE IN RELATIVELY GOOD AGREEMENT WITH REGARDS TO
LARGE SCALE IN THE EXTENDED PD. BOTH ALSO SUGGESTING LITTLE CHANGE
NEEDED TO GOING FCST.
HEADING INTO NEXT WEEKEND...MODELS ADVERTISE SHORTWAVE ENERGY OVER
IA QUICKLY LIFTING TO THE GREAT LAKES REGION LATE THURSDAY NIGHT.
MEANWHILE UPSTREAM...A DEEP LONGWAVE TROF IS PROGGED TO EXTEND FROM
CNTRL CANADA ALL THE WAY TO THE SWRN CONUS. ON FRIDAY AS THE WRN
TROF GRADUALLY MIGRATES EAST...INTENSE BAROCLINIC ZONE BEGINS
SWEEPING ACROSS THE NRN/CNTRL PLAINS WITH THE LEADING EDGE OF THE
BOUNDARY REACHING THE CWA BY EARLY AFTN. COMBINATION OF INCREASING
MOISTURE AND STOUT AGEOSTROPHIC LIFT ALONG DEEP FRONTOGENETIC LYR
SHOULD BE ENOUGH TO INDUCE LIGHT SNOW ACTIVITY DURING THE FROPA
FRIDAY NIGHT.
ON SATURDAY...APPEARS TO BE A SMALL CHANCE FOR LIGHT POST-FRONTAL
SNOW ACTIVITY PER THE ECM. 300-500MB QVEC CONVERGENCE IMPLYING LIFT
VIA DPVA WHEN POTENT OR MAX ROUNDS THE BASE OF THE WRN TROF AND
LIFTS ACROSS THE CNTRL PLAINS. ON THE OTHER HAND...GFS AND CMC BOTH
SUGGESTING THE DEEP CAA WILL BE ADEQUATE TO SUPPRESS ANY LIFT VIA
DPVA. WILL OPTED FOR TOKEN 20S JUST IN CASE ECM SOLUTION WOULD
VERIFY.
OTHERWISE...TEMPS WILL PLUMMET OVER THE PLAINS NEXT WEEKEND INTO
EARLY NEXT WEEK. EXPECT HIGHS SAT-MON WILL STRUGGLE TO REACH THE
LOWER/MID 20S.
DEE
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
99/99
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1231 PM EST TUE JAN 8 2013
.SYNOPSIS...
A COASTAL TROUGH JUST OFFSHORE WILL WEAKEN TONIGHT AS A RIDGE OF
HIGH PRESSURE TO OUR NORTH EXPANDS. LOW PRESSURE MOVING NORTHEAST
OUT OF THE PLAIN STATES WILL BRING A WARM FRONT ACROSS THE EASTERN
CAROLINAS ON FRIDAY. HIGH PRESSURE WILL BRING AN END TO THE
UNSETTLED WEATHER WITH WARM AND DRY CONDITIONS FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 PM TUESDAY...WELL WELL...THE COMBO OF THE HRRR/RUC
MENTIONED EARLIER AS UNLIKELY APPEARS TO HAVE BEEN THE WAY TO GO.
DESPITE THE SYNOPTIC PATTERN AND LOW LEVEL WINDS FAVORING A
CONTINUATION OF THE WEDGE-LIKE CONDITIONS SKIES HAVE AT LEAST
TEMPORARILY BECOME MOSTLY SUNNY ACROSS MOST OF OUR FORECAST AREA
WEST OF THE IMMEDIATE NORTH CAROLINA COAST AND TEMPERATURES ARE
ROCKETING THROUGH THE 50S. DENSER MID-LEVEL CLOUDS ACROSS SOUTHERN
AND CENTRAL SOUTH CAROLINA WILL MOVE INTO THE REGION IN THE NEXT
COUPLE OF HOURS WHICH SHOULD STOP THE TEMPERATURES FROM RISING...BUT
UNTIL THEN BASED ON CURRENT DATA I AM EXPANDING THE AREA EXPECTED TO
REACH 60-62 DEGREES TO COVER MOST OF OUR SOUTH CAROLINA FORECAST
AREA EAST OF I-95 AND AWAY FROM THE BEACHES. ACROSS SE NORTH
CAROLINA MOST PLACES SHOULD REACH THE UPPER 50S...EXCEPT WITHIN 5-10
MILES OF THE NEW HANOVER AND PENDER COUNTY COAST WHERE STUBBORN
CLOUDS AND THE REMNANT OF THIS MORNING`S CHILLY LOW-LEVEL AIRMASS
WILL HOLD TEMPERATURES SEVERAL DEGREES COOLER. PREVIOUS DISCUSSION
FROM 930 AM FOLLOWS...
HIGH PRESSURE ALONG THE MID-ATLANTIC COAST AND A WEAK COASTAL TROUGH
ROUGHLY 30-40 MILES OFFSHORE ARE PRODUCING A COOL NORTHEAST WIND
ACROSS THE EASTERN CAROLINAS. SATELLITE SHOWS LOW AND MID-LEVEL
CLOUD COVER ASSOCIATED WITH MOIST ATLANTIC AIR OVERRIDING THE
SHALLOW COLD AIRMASS INLAND. THERE ARE SOME SIZABLE HOLES IN THESE
CLOUD DECKS MAINLY ACROSS EASTERN SOUTH CAROLINA...AND THIS IS
COMPLICATING OUR FORECAST FOR TODAY.
CONFIDENCE WITH RESPECT TO OUR HIGH TEMPERATURE FORECAST REMAINS
RATHER LOW. THE BULK OF MODEL GUIDANCE INCLUDING THE LATEST RUC AND
HRRR MODELS ARE SIGNIFICANTLY WARMER THAN OUR FORECAST TODAY. IN
FACT...BLENDING THE RUC AND HRRR GIVES LOW TO MID 60S ACROSS MOST OF
OUR AREA WITH 50S ONLY HANGING AROUND NEAR THE BEACHES AND AROUND
LUMBERTON. THIS MAY BE UNREASONABLY WARM GIVEN THE WEDGE-LIKE
CONFIGURATION TO LOW-LEVEL WINDS...MOSTLY CLOUDY SKIES...AND THE
COASTAL TROUGH REMAINING OFFSHORE. THE ONLY AREA WHERE LOW 60S ARE
CURRENTLY FORECAST IS IN THE NARROW ZONE OF EASTERN SOUTH CAROLINA
EAST OF I-95 BUT AWAY FROM THE BEACHES INCLUDING CONWAY...SOUTHERN
MARION COUNTY...INLAND GEORGETOWN COUNTY AND WILLIAMSBURG COUNTY.
ELSEWHERE...MID 50S SHOULD PREDOMINATE.
RADAR IMAGERY SHOWS A PATCH OF LIGHT RAIN SITUATED IN THE ZONE OF
STRONGEST ISENTROPIC LIFT NEAR AND JUST EAST OF BALD HEAD ISLAND.
THIS SHOULD SHIFT NORTH OVER THE NEXT FEW HOURS BUT WILL LARGELY
DISSIPATE THIS AFTERNOON. OTHERWISE DRY CONDITIONS SHOULD CONTINUE.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 330 AM TUESDAY...DEVELOPING LOW PRESSURE SYSTEM OVER THE TEXAS
GULF COAST WILL TRACK NORTH TOWARD THE GREAT LAKES THROUGH THE
PERIOD. AS THE MID TO UPPER LOW DEEPENS OVER THE MID WEST...THE
RIDGE BECOMES MORE AMPLIFIED UP THROUGH THE SOUTHEAST COAST.
MODELS STILL SHOWING H5 HEIGHTS REACHING UP NEAR 588 DEM BY THURS
MORNING. WAA WILL BRING 850 TEMPS UP CLOSE TO 12C BY THURS BUT A
SHALLOW COOLER ON SHORE FLOW WILL EXIST AT THE SURFACE THROUGH
MID WEEK. INTERESTING SCENARIO AS COASTAL TROUGH WILL EXIST UP
THROUGH THE COASTAL CAROLINAS WITH COOLER NE FLOW INLAND AND
SOUTHEAST FLOW OFF SHORE REACHING THE COAST. THIS COASTAL TROUGH
WILL PROVIDE FOCUS FOR CLOUDS AND SOME PCP MAINLY TO THE SOUTH
THROUGH WEDNESDAY WHILE HIGH PRESSURE TO THE NORTH WILL PUSH A
BACKDOOR COLD FRONT INTO NORTH CAROLINA OVERNIGHT WED. THE GFS SHOWS
THIS BOUNDARY MAKING IT INTO LOCAL CWA BY THURS MORNING BUT THEN
RETURNING NORTH AS WARM FRONT. THIS MAY REINFORCE SHALLOW COOLER
AIR BRIEFLY AT THE SURFACE WHILE WINDS ALOFT INCREASE OUT OF THE
SOUTH AS STORM SYSTEM OVER THE MID WEST STRENGTHENS. EXPECT DECENT
AMOUNT OF LOW LEVEL CLOUDS THROUGH WED BUT SUBSIDENCE AND DRY AIR
THROUGH THE MID LEVELS SHOULD PREVENT MUCH IN THE WAY OF PCP UNTIL
LATE WED INTO THURS WHEN COASTAL TROUGH/WARM FRONT MAKES PROGRESS
INLAND AND NORTH. WILL KEEP BEST CHC OF MEASURABLE PCP AND
HIGHEST QPF DURING THURS. SHOULD SEE AN END TO MOST OF THE PCP
HEADING INTO THURS EVENING AS BEST LIFT SHIFTS NORTH OF AREA AS
WARM FRONT GETS PULLED NORTH AS STORM SYSTEM MOVES UP INTO THE
GREAT LAKES. OVERALL WILL SEE CLOUDS THROUGH MOST OF THE PERIOD
AND BEST CHC OF PCP OVERNIGHT WED INTO EARLY THURS.
TEMPS MAY BE A BIT TRICKY WITH CLOUDS AND PCP BEING OFFSET BY WAA
AND RIDGE BUILDING ALOFT WITH H5 HEIGHT INCREASES. THEN THE
BACKDOOR COLD FRONT MAY PROVIDE ANOTHER BURST OF VERY SHALLOW COOL
AIR FOR THURS MORNING BEFORE WARM FRONT MOVES NORTH OF AREA.
EXPECT MAX TEMPS UP INTO THE 60S AND LOWS REMAINING CLOSE TO 50 OR
ABOVE.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 3 AM TUESDAY...STRONG RIDGE BUILDING UP FROM THE BAHAMAS
UP THROUGH THE SOUTHEAST WILL BECOME TEMPORARILY DISRUPTED EARLY
FRIDAY AS IT TRACKS ACROSS THE CAROLINAS. ONCE THIS SHORTWAVE
CLEARS THE COAST IT WILL PUSH A COLD FRONT FARTHER EAST AWAY FROM
AREA ALLOWING HIGH PRESSURE TO DOMINATE THROUGH THE WEEKEND INTO
EARLY NEXT WEEK. THE RIDGE AXIS WILL RIDE UP RIGHT ALONG THE
SOUTHEAST COAST WITH CENTER OF THE SURFACE HIGH DISPLACED TO THE
EAST. THIS WILL PRODUCE A DEEP W-SW RETURN FLOW THROUGH MOST OF
THE PERIOD WITH PLENTY OF SUBSIDENCE AND DRY AIR THROUGH THE MID
LEVELS OF THE ATMOSPHERE. SOME LOW LEVEL MOISTURE SHOULD PRODUCE
SOME CLOUDS THROUGH THE PERIOD.
H5 HEIGHTS REMAIN AROUND 585 DEM AS RIDGE HOLDS ON TIGHT THROUGH THE
WEEKEND. 850 TEMPS HOLD UP TO 13 TO 14 C IN WAA INTO EARLY NEXT
WEEK. OVERALL EXPECT TEMPS TO BE WELL ABOVE NORMAL WITH AFTERNOON
HIGHS INTO THE 70S AND OVERNIGHT LOWS CLOSE TO NORMAL HIGHS FOR
THIS TIME OF YEAR...IN THE MID 50S.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
AS OF 18Z...VISIBLE SATELLITE IMAGERY SHOWS SCT/BKN LOW TO MID LEVEL
CLOUDS ACROSS THE CWA ASSOCIATED WITH A WEAK COASTAL TROUGH. THIS
CLOUD COVER IS EXPECTED TO LINGER INTO THE OVERNIGHT HOURS. MOIST
RETURN FLOW AROUND THE HIGH PRESSURE CENTERED OFFSHORE HAS INCREASED
DEWPOINTS ACROSS THE AREA. FORECAST SOUNDINGS SHOW A PRONOUNCED
LOW-LEVEL INVERSION DEVELOPING OVERNIGHT...WHICH SHOULD TRAP THIS
MOISTURE NEAR THE SURFACE AND SUPPORT FOG/STRATUS DEVELOPMENT EARLY
WEDNESDAY. BASED ON THE LATEST MODEL GUIDANCE...HAVE INCREASING
CONFIDENCE FOR MVFR CIGS/VSBYS AT ALL TERMS AFTER 06Z...BECOMING IFR
IN THE EARLY MORNING HOURS. CONDITIONS SHOULD IMPROVE TO MVFR BY
LATE WEDNESDAY MORNING. EXPECT EAST WINDS AOB 8 KNOTS TODAY WITH
LIGHT AND VARIABLE WINDS OVERNIGHT.
EXTENDED OUTLOOK...SLIGHT CHANCE OF SHOWERS LATE WEDNESDAY INTO
THURSDAY. POSSIBLE MVFR/IFR CIGS/VSBYS THURSDAY MORNING. VFR
DEVELOPING FRIDAY AND PERSISTING THROUGH SUNDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 PM TUESDAY...COOL NORTHEAST WINDS CONTINUE ACROSS THE
COASTAL WATERS...ALTHOUGH WITH WIND SPEEDS NOTABLY LESS THAN
OBSERVED 3-6 HOURS AGO. THIS IS INLINE WITH OUR PREVIOUS FORECAST
AND NO SIGNIFICANT CHANGES ARE NEEDED THROUGH THIS EVENING. PREVIOUS
DISCUSSION FROM 930 AM FOLLOWS...
BASED ON DATA FROM THE FRYING PAN SHOALS BUOY SHOWING A SOUTHEAST
WIND AND 66 DEGREE AIR TEMPERATURES...THE COASTAL TROUGH LIES JUST
TO THEIR WEST. ALL OTHER BUOY AND COASTAL LOCATIONS HAVE MUCH COLDER
AIR TEMPERATURES WITH NORTH TO NORTHEAST WINDS. MODEL CONSENSUS IS
THIS TROUGH SHOULD WEAKEN THIS AFTERNOON AND ESPECIALLY TONIGHT AS
THE HIGH ALONG THE MID-ATLANTIC COAST NUDGES BACK TO THE SOUTH.
RADAR SHOWS SOME PATCHY LIGHT RAIN JUST EAST OF CAPE FEAR CURRENTLY.
THIS PRECIPITATION SHOULD MOVE SLOWLY NORTH THIS MORNING POTENTIALLY
AFFECTING THE COASTAL WATERS NEAR CAROLINA BEACH BEFORE DISSIPATING
THIS AFTERNOON.
THE SURGE OF STRONG NORTH-NORTHEAST WINDS EARLIER THIS MORNING IS
DIMINISHING AND BY THIS AFTERNOON WIND SPEEDS SHOULD REMAIN BELOW 15
KNOTS. SEAS HAVE ALSO STARTED DIMINISHING WITH 5 FT SEAS AT THE
FRYING PAN SHOALS BUOY AND 4 FT AT THE NEARSHORE WRIGHTSVILLE BEACH
BUOY. THE EXERCISE CAUTION HEADLINE WILL CONTINUE FOR THE NC WATERS
THROUGH 11 AM.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...COASTAL TROUGH ON WED BECOMES DAMPENED AS
HIGH PRESSURE PUSHES A BACK DOOR COLD FRONT SOUTH. SHOULD SEE
LIGHT E-SE FLOW THROUGH WED 10 KTS OR LESS. FLOW MAY SHIFT AROUND
TO THE NE BRIEFLY EARLY THURS AS WEAK BACKDOOR FRONT MOVES INTO
AREA BUT THIS WILL MOVE BACK NORTH AS WARM FRONT ON THURSDAY WITH
AN INCREASING SOUTHERLY FLOW DEVELOPING THURS NIGHT. SEAS WILL
BASICALLY REMAIN 3 FT OR LESS THROUGH THURS MORNING AND THEN WILL
RISE UP TO 3 TO 5 FT IN INCREASING SOUTHERLY PUSH LATE THURS INTO
FRI.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 AM TUESDAY...SOUTHERLY FLOW AROUND 15 KTS WILL VEER TO THE
SOUTHWEST AND LIGHTEN THROUGH THE FIRST HALF OF THE WEEKEND AS HIGH
PRESSURE OVER THE LOCAL WATERS SHIFTS SOUTH AND WEST. OVERALL
GRADIENT WILL RELAX THROUGH SATURDAY. EXPECT WINDS TO LIGHTEN TO
10 KTS OR LESS BY LATE SAT WITH SEAS DIMINISHING FROM 3-5 FEET ON
FRI DOWN TO 2 TO 3 FT BY SAT NIGHT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1210 PM EST TUE JAN 8 2013
.SYNOPSIS...
A COASTAL TROUGH JUST OFFSHORE WILL WEAKEN TONIGHT AS A RIDGE OF
HIGH PRESSURE TO OUR NORTH EXPANDS. LOW PRESSURE MOVING NORTHEAST
OUT OF THE PLAIN STATES WILL BRING A WARM FRONT ACROSS THE EASTERN
CAROLINAS ON FRIDAY. HIGH PRESSURE WILL BRING AN END TO THE
UNSETTLED WEATHER WITH WARM AND DRY CONDITIONS FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 PM TUESDAY...WELL WELL...THE COMBO OF THE HRRR/RUC
MENTIONED EARLIER AS UNLIKELY APPEARS TO HAVE BEEN THE WAY TO GO.
DESPITE THE SYNOPTIC PATTERN AND LOW LEVEL WINDS FAVORING A
CONTINUATION OF THE WEDGE-LIKE CONDITIONS SKIES HAVE AT LEAST
TEMPORARILY BECOME MOSTLY SUNNY ACROSS MOST OF OUR FORECAST AREA
WEST OF THE IMMEDIATE NORTH CAROLINA COAST AND TEMPERATURES ARE
ROCKETING THROUGH THE 50S. DENSER MID-LEVEL CLOUDS ACROSS SOUTHERN
AND CENTRAL SOUTH CAROLINA WILL MOVE INTO THE REGION IN THE NEXT
COUPLE OF HOURS WHICH SHOULD STOP THE TEMPERATURES FROM RISING...BUT
UNTIL THEN BASED ON CURRENT DATA I AM EXPANDING THE AREA EXPECTED TO
REACH 60-62 DEGREES TO COVER MOST OF OUR SOUTH CAROLINA FORECAST
AREA EAST OF I-95 AND AWAY FROM THE BEACHES. ACROSS SE NORTH
CAROLINA MOST PLACES SHOULD REACH THE UPPER 50S...EXCEPT WITHIN 5-10
MILES OF THE NEW HANOVER AND PENDER COUNTY COAST WHERE STUBBORN
CLOUDS AND THE REMNANT OF THIS MORNING`S CHILLY LOW-LEVEL AIRMASS
WILL HOLD TEMPERATURES SEVERAL DEGREES COOLER. PREVIOUS DISCUSSION
FROM 930 AM FOLLOWS...
HIGH PRESSURE ALONG THE MID-ATLANTIC COAST AND A WEAK COASTAL TROUGH
ROUGHLY 30-40 MILES OFFSHORE ARE PRODUCING A COOL NORTHEAST WIND
ACROSS THE EASTERN CAROLINAS. SATELLITE SHOWS LOW AND MID-LEVEL
CLOUD COVER ASSOCIATED WITH MOIST ATLANTIC AIR OVERRIDING THE
SHALLOW COLD AIRMASS INLAND. THERE ARE SOME SIZABLE HOLES IN THESE
CLOUD DECKS MAINLY ACROSS EASTERN SOUTH CAROLINA...AND THIS IS
COMPLICATING OUR FORECAST FOR TODAY.
CONFIDENCE WITH RESPECT TO OUR HIGH TEMPERATURE FORECAST REMAINS
RATHER LOW. THE BULK OF MODEL GUIDANCE INCLUDING THE LATEST RUC AND
HRRR MODELS ARE SIGNIFICANTLY WARMER THAN OUR FORECAST TODAY. IN
FACT...BLENDING THE RUC AND HRRR GIVES LOW TO MID 60S ACROSS MOST OF
OUR AREA WITH 50S ONLY HANGING AROUND NEAR THE BEACHES AND AROUND
LUMBERTON. THIS MAY BE UNREASONABLY WARM GIVEN THE WEDGE-LIKE
CONFIGURATION TO LOW-LEVEL WINDS...MOSTLY CLOUDY SKIES...AND THE
COASTAL TROUGH REMAINING OFFSHORE. THE ONLY AREA WHERE LOW 60S ARE
CURRENTLY FORECAST IS IN THE NARROW ZONE OF EASTERN SOUTH CAROLINA
EAST OF I-95 BUT AWAY FROM THE BEACHES INCLUDING CONWAY...SOUTHERN
MARION COUNTY...INLAND GEORGETOWN COUNTY AND WILLIAMSBURG COUNTY.
ELSEWHERE...MID 50S SHOULD PREDOMINATE.
RADAR IMAGERY SHOWS A PATCH OF LIGHT RAIN SITUATED IN THE ZONE OF
STRONGEST ISENTROPIC LIFT NEAR AND JUST EAST OF BALD HEAD ISLAND.
THIS SHOULD SHIFT NORTH OVER THE NEXT FEW HOURS BUT WILL LARGELY
DISSIPATE THIS AFTERNOON. OTHERWISE DRY CONDITIONS SHOULD CONTINUE.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 330 AM TUESDAY...DEVELOPING LOW PRESSURE SYSTEM OVER THE TEXAS
GULF COAST WILL TRACK NORTH TOWARD THE GREAT LAKES THROUGH THE
PERIOD. AS THE MID TO UPPER LOW DEEPENS OVER THE MID WEST...THE
RIDGE BECOMES MORE AMPLIFIED UP THROUGH THE SOUTHEAST COAST.
MODELS STILL SHOWING H5 HEIGHTS REACHING UP NEAR 588 DEM BY THURS
MORNING. WAA WILL BRING 850 TEMPS UP CLOSE TO 12C BY THURS BUT A
SHALLOW COOLER ON SHORE FLOW WILL EXIST AT THE SURFACE THROUGH
MID WEEK. INTERESTING SCENARIO AS COASTAL TROUGH WILL EXIST UP
THROUGH THE COASTAL CAROLINAS WITH COOLER NE FLOW INLAND AND
SOUTHEAST FLOW OFF SHORE REACHING THE COAST. THIS COASTAL TROUGH
WILL PROVIDE FOCUS FOR CLOUDS AND SOME PCP MAINLY TO THE SOUTH
THROUGH WEDNESDAY WHILE HIGH PRESSURE TO THE NORTH WILL PUSH A
BACKDOOR COLD FRONT INTO NORTH CAROLINA OVERNIGHT WED. THE GFS SHOWS
THIS BOUNDARY MAKING IT INTO LOCAL CWA BY THURS MORNING BUT THEN
RETURNING NORTH AS WARM FRONT. THIS MAY REINFORCE SHALLOW COOLER
AIR BRIEFLY AT THE SURFACE WHILE WINDS ALOFT INCREASE OUT OF THE
SOUTH AS STORM SYSTEM OVER THE MID WEST STRENGTHENS. EXPECT DECENT
AMOUNT OF LOW LEVEL CLOUDS THROUGH WED BUT SUBSIDENCE AND DRY AIR
THROUGH THE MID LEVELS SHOULD PREVENT MUCH IN THE WAY OF PCP UNTIL
LATE WED INTO THURS WHEN COASTAL TROUGH/WARM FRONT MAKES PROGRESS
INLAND AND NORTH. WILL KEEP BEST CHC OF MEASURABLE PCP AND
HIGHEST QPF DURING THURS. SHOULD SEE AN END TO MOST OF THE PCP
HEADING INTO THURS EVENING AS BEST LIFT SHIFTS NORTH OF AREA AS
WARM FRONT GETS PULLED NORTH AS STORM SYSTEM MOVES UP INTO THE
GREAT LAKES. OVERALL WILL SEE CLOUDS THROUGH MOST OF THE PERIOD
AND BEST CHC OF PCP OVERNIGHT WED INTO EARLY THURS.
TEMPS MAY BE A BIT TRICKY WITH CLOUDS AND PCP BEING OFFSET BY WAA
AND RIDGE BUILDING ALOFT WITH H5 HEIGHT INCREASES. THEN THE
BACKDOOR COLD FRONT MAY PROVIDE ANOTHER BURST OF VERY SHALLOW COOL
AIR FOR THURS MORNING BEFORE WARM FRONT MOVES NORTH OF AREA.
EXPECT MAX TEMPS UP INTO THE 60S AND LOWS REMAINING CLOSE TO 50 OR
ABOVE.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 3 AM TUESDAY...STRONG RIDGE BUILDING UP FROM THE BAHAMAS
UP THROUGH THE SOUTHEAST WILL BECOME TEMPORARILY DISRUPTED EARLY
FRIDAY AS IT TRACKS ACROSS THE CAROLINAS. ONCE THIS SHORTWAVE
CLEARS THE COAST IT WILL PUSH A COLD FRONT FARTHER EAST AWAY FROM
AREA ALLOWING HIGH PRESSURE TO DOMINATE THROUGH THE WEEKEND INTO
EARLY NEXT WEEK. THE RIDGE AXIS WILL RIDE UP RIGHT ALONG THE
SOUTHEAST COAST WITH CENTER OF THE SURFACE HIGH DISPLACED TO THE
EAST. THIS WILL PRODUCE A DEEP W-SW RETURN FLOW THROUGH MOST OF
THE PERIOD WITH PLENTY OF SUBSIDENCE AND DRY AIR THROUGH THE MID
LEVELS OF THE ATMOSPHERE. SOME LOW LEVEL MOISTURE SHOULD PRODUCE
SOME CLOUDS THROUGH THE PERIOD.
H5 HEIGHTS REMAIN AROUND 585 DEM AS RIDGE HOLDS ON TIGHT THROUGH THE
WEEKEND. 850 TEMPS HOLD UP TO 13 TO 14 C IN WAA INTO EARLY NEXT
WEEK. OVERALL EXPECT TEMPS TO BE WELL ABOVE NORMAL WITH AFTERNOON
HIGHS INTO THE 70S AND OVERNIGHT LOWS CLOSE TO NORMAL HIGHS FOR
THIS TIME OF YEAR...IN THE MID 50S.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 12Z...VFR/MVFR CIGS ACROSS THE AREA THIS MORNING AS SATELLITE
IMAGERY DEPICTS PLENTY OF LOW-LEVEL CLOUD COVER ASSOCIATED WITH A
COASTAL TROUGH. MOIST RETURN FLOW AROUND THE HIGH PRESSURE CENTERED
OFFSHORE WILL KEEP THE LOW CLOUDS AROUND THROUGH THIS TAF PERIOD. IT
APPEARS THAT LOW VFR CIGS WILL BE MOST PREVALENT ACROSS THE AREA
TODAY...ALTHOUGH SOME MVFR CIGS ARE POSSIBLE AS WELL. COULD SEE SOME
ISOLATED DRIZZLE ALONG THE COAST...BUT DECIDED IT WAS NOT WORTH
MENTIONING IN TAFS. EXPECT EAST WINDS AOB 8 KNOTS TODAY...BECOMING
LIGHT/CALM OVERNIGHT. MODEL SOUNDINGS AND GUIDANCE BOTH SUPPORT A
FOG/STRATUS EVENT OVERNIGHT WITH ABUNDANT LOW-LEVEL MOISTURE IN
PLACE ACROSS THE REGION. INCLUDED MVFR CIGS/VSBYS AFTER MIDNIGHT AT
ALL TERMINALS...AND IFR CONDITIONS COULD DEVELOP TOWARDS THE END OF
THE TAF PERIOD.
EXTENDED OUTLOOK...POSSIBLE MVFR/IFR CIGS WEDNESDAY AND THURSDAY.
SLIGHT CHANCE OF SHOWERS LATE WEDNESDAY INTO THURSDAY. VFR
DEVELOPING FRIDAY AND PERSISTING THROUGH SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 PM TUESDAY...COOL NORTHEAST WINDS CONTINUE ACROSS THE
COASTAL WATERS...ALTHOUGH WITH WIND SPEEDS NOTABLY LESS THAN
OBSERVED 3-6 HOURS AGO. THIS IS INLINE WITH OUR PREVIOUS FORECAST
AND NO SIGNIFICANT CHANGES ARE NEEDED THROUGH THIS EVENING. PREVIOUS
DISCUSSION FROM 930 AM FOLLOWS...
BASED ON DATA FROM THE FRYING PAN SHOALS BUOY SHOWING A SOUTHEAST
WIND AND 66 DEGREE AIR TEMPERATURES...THE COASTAL TROUGH LIES JUST
TO THEIR WEST. ALL OTHER BUOY AND COASTAL LOCATIONS HAVE MUCH COLDER
AIR TEMPERATURES WITH NORTH TO NORTHEAST WINDS. MODEL CONSENSUS IS
THIS TROUGH SHOULD WEAKEN THIS AFTERNOON AND ESPECIALLY TONIGHT AS
THE HIGH ALONG THE MID-ATLANTIC COAST NUDGES BACK TO THE SOUTH.
RADAR SHOWS SOME PATCHY LIGHT RAIN JUST EAST OF CAPE FEAR CURRENTLY.
THIS PRECIPITATION SHOULD MOVE SLOWLY NORTH THIS MORNING POTENTIALLY
AFFECTING THE COASTAL WATERS NEAR CAROLINA BEACH BEFORE DISSIPATING
THIS AFTERNOON.
THE SURGE OF STRONG NORTH-NORTHEAST WINDS EARLIER THIS MORNING IS
DIMINISHING AND BY THIS AFTERNOON WIND SPEEDS SHOULD REMAIN BELOW 15
KNOTS. SEAS HAVE ALSO STARTED DIMINISHING WITH 5 FT SEAS AT THE
FRYING PAN SHOALS BUOY AND 4 FT AT THE NEARSHORE WRIGHTSVILLE BEACH
BUOY. THE EXERCISE CAUTION HEADLINE WILL CONTINUE FOR THE NC WATERS
THROUGH 11 AM.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...COASTAL TROUGH ON WED BECOMES DAMPENED AS
HIGH PRESSURE PUSHES A BACK DOOR COLD FRONT SOUTH. SHOULD SEE
LIGHT E-SE FLOW THROUGH WED 10 KTS OR LESS. FLOW MAY SHIFT AROUND
TO THE NE BRIEFLY EARLY THURS AS WEAK BACKDOOR FRONT MOVES INTO
AREA BUT THIS WILL MOVE BACK NORTH AS WARM FRONT ON THURSDAY WITH
AN INCREASING SOUTHERLY FLOW DEVELOPING THURS NIGHT. SEAS WILL
BASICALLY REMAIN 3 FT OR LESS THROUGH THURS MORNING AND THEN WILL
RISE UP TO 3 TO 5 FT IN INCREASING SOUTHERLY PUSH LATE THURS INTO
FRI.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 AM TUESDAY...SOUTHERLY FLOW AROUND 15 KTS WILL VEER TO THE
SOUTHWEST AND LIGHTEN THROUGH THE FIRST HALF OF THE WEEKEND AS HIGH
PRESSURE OVER THE LOCAL WATERS SHIFTS SOUTH AND WEST. OVERALL
GRADIENT WILL RELAX THROUGH SATURDAY. EXPECT WINDS TO LIGHTEN TO
10 KTS OR LESS BY LATE SAT WITH SEAS DIMINISHING FROM 3-5 FEET ON
FRI DOWN TO 2 TO 3 FT BY SAT NIGHT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1016 AM EST TUE JAN 8 2013
.SYNOPSIS...
HIGH PRESSURE WILL LINGER OVER THE AREA THROUGH WEDNESDAY. A
BACKDOOR COLD FRONT WILL PUSH INTO THE REGION THURSDAY... THEN
RETURN NORTH AS A WARM FRONT LATE FRIDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 305 AM TUESDAY...
REST OF TODAY:
SOUTHWEST FLOW ALOFT WILL PREVAIL TODAY...DOWNSTREAM OF A POTENT
UPPER LEVEL LOW MEANDERING EASTWARD ACROSS NORTHERN MEXICO. SMALL
AMPLITUDE DISTURBANCES WILL PROGRESS INTO THE CAROLINAS VIA SW FLOW
ALOFT THIS AFTERNOON...THOUGH NO APPRECIABLE DPVA IS ANTICIPATED. A
RELATIVELY WEAK 925-850 MB RETURN FLOW IS IN PLACE TODAY...ON THE
WESTERN PERIPHERY OF A LOW-LEVEL RIDGE CENTERED JUST OFFSHORE IN THE
ATLANTIC. AT THE SURFACE...LITTLE OR NO ADVECTION WILL OCCUR IN THE
PRESENCE OF A SFC RIDGE AXIS EXTENDING NORTHEAST FROM UPSTATE SC TO
SOUTHEAST VA. BROKEN TO OVERCAST LOW-LEVEL CLOUD COVER THIS MORNING
MAY PERSIST INTO THE AFTERNOON IN ASSOC/W LOW-LEVEL WARM
ADVECTION...ESP OVER THE NORTHERN PIEDMONT AND NE COASTAL PLAIN.
UNCERTAINTY IN CLOUD COVER AND RESULTING TEMPERATURES ARE THE
PRIMARY FCST PROBLEM. GIVEN CURRENT OBS/SAT IMAGERY AND REASONABLE
FORCING FOR CLOUD COVER TO PERSIST THROUGH MUCH OF DIURNAL
HEATING...HAVE OPTED TO LOWER HIGH TEMPS A FEW DEGREES...RANGING
FROM 50-54F (WARMEST FAR S/SE AND COOLEST N/NE). THOUGH LOW-LEVEL
FORCING SHOULD BE SUFFICIENT TO SUPPORT BROKEN TO OVERCAST CLOUD
COVER...OVERALL FORCING AND MOISTURE WILL BE INSUFFICIENT TO SUPPORT
PRECIPITATION. -VINCENT
TONIGHT...
CONTINUATION OF THE RETURN FLOW AROUND OF THE ELONGATING SURFACE
RIDGE AXIS WILL LEAD TO STRATUS AGAIN OVERNIGHT. FORECAST SOUNDINGS
ARE SUPPORTED BY HIGH SREF PROBABILITIES OF LOW CEILINGS OVER THE
WESTERN PIEDMONT. HIGH CLOUDS SHOULD ALSO BE ON THE INCREASE AS
MOISTURE STREAMS IN FROM THE SOUTHWEST AHEAD OF AN UPPER LOW MOVING
SLOWLY ACROSS THE TX/MEXICO BORDER. MOSTLY CLOUDY SKIES SHOULD
LIMIT ANY FOG POTENTIAL...BUT WITH DEWPOINTS CREEPING UP INTO THE
LOWER 40S AND WEAK WINDS WITHIN THE SURFACE RIDGE AXIS...THERE COULD
BE SOME PATCHY FOG IN THE SOUTH AND EAST LATE TONIGHT. LOWS 37-42.
WEDNESDAY...
THE AIRMASS OVER CENTRAL NC WILL CONTINUE TO MOISTEN WEDNESDAY AS
HIGH PRESSURE LINGERS OFF THE COAST AND RETURN FLOW PERSISTS. AN
UNSEASONABLY STRONG SUBTROPICAL RIDGE WILL HOLD OVER THE SOUTHEAST
US...WHILE ONE SHORTWAVE CROSSES THE GREAT LAKES REGION AND THE
AFOREMENTIONED UPPER LOW OVER TX BEGINS TO LIFT NORTH THROUGH THE
SOUTHERN PLAINS. MODELS GENERATE SOME VERY LIGHT QPF LATE IN THE DAY
ACROSS THE SOUTHERN CWA...BUT THIS APPEARS TO BE OVERDONE GIVEN THE
LACK OF FORCING. WILL MAINTAIN A DRY FORECAST FOR WEDNESDAY. LOW
LEVEL THICKNESSES APPROACH 1370M BY WEDNESDAY AFTERNOON..BUT AS PW
VALUES RISE TO NEAR ONE INCH... THERE SHOULD AGAIN BE SOME IMPACT OF
CLOUD COVER ON HEATING. HIGHS 61-66.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 300 AM TUESDAY...
A HYBRID COLD AIR DAMMING EVENT LIKELY LATE THURSDAY INTO FRIDAY...
THE EVOLVING PATTERN CONSISTING OF A DEEP WEST-CENTRAL U.S. TROUGH
AND STRONGLY RISING UPPER HEIGHTS FROM THE CARIBBEAN THROUGH THE
SOUTHEAST U.S. LATE WEEK INTO THE WEEKEND WILL EVENTUALLY MEAN A
WARM AND MOSTLY DRY PERIOD FOR OUR REGION THIS WEEKEND. BEFORE THAT
OCCURS... A HYBRID CAD EVENT IS EXPECTED TO DEVELOP OVER THE
PIEDMONT DAMMING REGION THURSDAY AND LAST INTO FRIDAY.
THE WARMING ASSOCIATED WITH RISING HEIGHTS ALOFT WILL INITIALLY BE
OFFSET BY THE STRONG (1035+ MB) SURFACE HIGH THAT IS EXPECTED TO
BUILD EAST FROM THE OHIO VALLEY TO THE NEW ENGLAND COAST THURSDAY
INTO EARLY FRIDAY. THE STRENGTH AND POSITION OF THIS HIGH PRESSURE
IS VERY FAVORABLE FOR CAD DEEP INTO OUR REGION. THE HIGH IS FORECAST
TO BE PROGRESSIVE AS THE MID/UPPER FLOW OVER THE NE US BECOMES
CONFLUENT BY THE WEEKEND... MAKING THIS A HYBRID CAD EVENT... AND
ONE THAT WILL ERODE A BIT MORE QUICKLY THAN CLASSICAL CAD EPISODES.
INITIALLY ON THURSDAY... THE HIGH IS EXPECTED TO BUILD SOUTH... DOWN
THE EASTERN SEABOARD... WHEN THE SOUTHERN PLAINS STORM SYSTEM IS
FORECAST TO TRACK NE THROUGH THE OHIO VALLEY THU NIGHT. WARM MOIST
AIR IS EXPECTED TO OVERRUN THE COOL STABLE LAYER EAST OF THE
MOUNTAINS THU NIGHT AND FRIDAY... WITH AREAS OF RAIN
DEVELOPING/OVERSPREADING THE REGION. THIS WILL ALLOW THE CAD EVENT
TO SHAPE UP THURSDAY NIGHT INTO FRIDAY.
THE EVENTUAL DEPTH AND DURATION OF THE CAD SHOULD LARGELY BE DRIVEN
BY THE AMOUNT OF QPF THOSE PERIODS INTO THE COOL STABLE AIR...
LOCKING THE CAD IN PLACE. THE CURRENT FAVORED BLEND OF THE LATEST
GFS/EC OPERATIONAL MODELS AND EC ENSEMBLES INDICATE THE QPF TO
REACH THE CRITICAL 0.12 TO 0.25 THRESHOLD IN THE PIEDMONT DAMMING
REGION... SUFFICIENT TO LOCK IN THE CAD THURSDAY NIGHT INTO EARLY
FRIDAY. IF THIS IS REALIZED... THIS WILL DELAY THE THE WARM FRONT
FROM SURGING THROUGH CENTRAL NC ON FRIDAY MORNING. IT WOULD TAKE
MUCH OF THE DAY FOR THE DAMMING (PARTICULARLY THE RESIDUAL AFFECTS -
LOWS CLOUDS/FOG/DRIZZLE) TO ERODE. CURRENT THINKING IS THAT THE
PIEDMONT TRIAD REGION MAY VERY WELL HAVE CAD AFFECTS INTO SAT
MORNING.
SENSIBLE WEATHER...
PARTLY CLOUDY WEDNESDAY NIGHT WITH LOWS IN THE UPPER 30S TO MID 40S.
THURSDAY... INCREASING CLOUDS NE... MOSTLY CLOUDY TO CLOUDY WEST.
WINDS BECOMING ENE. HIGHS IN THE 50S TO LOWER 60S SE. THURSDAY NIGHT
AND EARLY FRIDAY... RAIN LIKELY NW AND A CHANCE SE. COOL IN THE
DAMMING REGION. LOWS IN THE 40S. LINGERING LOW CLOUDS AND LIGHT
RAIN/DRIZZLE FRIDAY IN THE DAMMING REGION. BECOMING MOSTLY CLOUDY
SE/WARMER. HIGHS 55 NW TO UPPER 60S SE. PARTLY CLOUDY TO CLOUDY
FRIDAY NIGHT. WARMER. LOWS 45-55. AREAS OF FOG/LOW CLOUDS AGAIN
LIKELY NW.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 300 TUESDAY...
THE LATEST MODELS SUPPORT THE SLOWER TIMING OF THE COLD FRONT BY
EARLY NEXT WEEK. THIS WILL ENSURE A WEEKEND OF WARM DRY WEATHER WITH
TEMPS 20 TO 30 DEGREES ABOVE NORMAL. WE WILL HOLD OFF MENTION OF ANY
SHOWERS UNTIL SUNDAY NIGHT OR MONDAY.
BECOMING PARTLY CLOUDY SATURDAY. BREEZY AND WARMER. HIGHS IN THE
UPPER 60S TO MID 70S. LOWS SAT NIGHT IN THE 50S (AVERAGE HIGHS ARE
48-53). SUNDAY... PARTLY SUNNY. HIGHS LOWER TO MID 70S. MONDAY...
MOSTLY CLOUDY WITH A CHANCE OF SHOWERS. HIGHS IN THE 60S TO LOWER
70S SE.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 645 AM TUESDAY...
WITH HIGH PRESSURE NOW SETTLING EAST ALONG THE COAST...EASTERLY LOW
LEVEL WINDS ARE BEGINNING TO USHER MOISTURE INLAND ACROSS THE
CAROLINAS. STRATOCU HAS SPREAD FROM SC NORTH ACROSS ALMOST ALL OF
CENTRAL NC. CEILINGS GENERALLY VARY FROM 5000FT NORTH TO 3000FT
SOUTH. BASED ON SATELLITE TRENDS AND HRRR MODEL MOISTURE
FIELDS...MVFR CEILINGS ARE MOSTLY LIKELY IN THE NEXT 3-6 HOURS AT
KFAY/KGSO/KINT. MVFR CEILINGS CANNOT BE RULED OUT AT KRDU AND/OR
KRWI..BUT CONFIDENCE IS MUCH LOWER AT THESE SITES. WHILE SOME
IMPROVEMENT IS FORECAST THIS AFTERNOON...THIS MOISTURE IS TRAPPED
BENEATH A STRONG SUBSIDENCE INVERSION LOCATED NEAR 5000FT...SO
CEILINGS ARE LIKELY TO REMAIN NEAR MVFR LEVELS THROUGHOUT THE DAY.
TONIGHT...AS WINDS CONTINUE TO SHIFT AROUND TO
SOUTH-SOUTHWESTERLY...THERE IS A BETTER CHANCE OF MVFR AND/OR IFR
CEILINGS..ESPECIALLY AT WESTERN TERMINALS (KGSO/KINT).
OUTLOOK...
AN EXTENDED PERIOD OF CLOUDINESS WITH SUB-VFR CONDITIONS IN LIGHT
RAIN WILL THEN BE POSSIBLE THURSDAY AND FRIDAY AS A WARM FRONT
APPROACHES FROM THE SOUTH-SOUTHWEST.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...VINCENT/SMITH
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
952 AM EST TUE JAN 8 2013
.SYNOPSIS...
A COASTAL TROUGH JUST OFFSHORE WILL WEAKEN TONIGHT AS A RIDGE OF
HIGH PRESSURE TO OUR NORTH EXPANDS. LOW PRESSURE MOVING NORTHEAST
OUT OF THE PLAIN STATES WILL BRING A WARM FRONT ACROSS THE EASTERN
CAROLINAS ON FRIDAY. HIGH PRESSURE WILL BRING AN END TO THE
UNSETTLED WEATHER WITH WARM AND DRY CONDITIONS FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM TUESDAY...HIGH PRESSURE ALONG THE MID-ATLANTIC
COAST AND A WEAK COASTAL TROUGH ROUGHLY 30-40 MILES OFFSHORE ARE
PRODUCING A COOL NORTHEAST WIND ACROSS THE EASTERN CAROLINAS.
SATELLITE SHOWS LOW AND MID-LEVEL CLOUD COVER ASSOCIATED WITH MOIST
ATLANTIC AIR OVERRIDING THE SHALLOW COLD AIRMASS INLAND. THERE ARE
SOME SIZABLE HOLES IN THESE CLOUD DECKS MAINLY ACROSS EASTERN SOUTH
CAROLINA...AND THIS IS COMPLICATING OUR FORECAST FOR TODAY.
CONFIDENCE WITH RESPECT TO OUR HIGH TEMPERATURE FORECAST REMAINS
RATHER LOW. THE BULK OF MODEL GUIDANCE INCLUDING THE LATEST RUC AND
HRRR MODELS ARE SIGNIFICANTLY WARMER THAN OUR FORECAST TODAY. IN
FACT...BLENDING THE RUC AND HRRR GIVES LOW TO MID 60S ACROSS MOST OF
OUR AREA WITH 50S ONLY HANGING AROUND NEAR THE BEACHES AND AROUND
LUMBERTON. THIS MAY BE UNREASONABLY WARM GIVEN THE WEDGE-LIKE
CONFIGURATION TO LOW-LEVEL WINDS...MOSTLY CLOUDY SKIES...AND THE
COASTAL TROUGH REMAINING OFFSHORE. THE ONLY AREA WHERE LOW 60S ARE
CURRENTLY FORECAST IS IN THE NARROW ZONE OF EASTERN SOUTH CAROLINA
EAST OF I-95 BUT AWAY FROM THE BEACHES INCLUDING CONWAY...SOUTHERN
MARION COUNTY...INLAND GEORGETOWN COUNTY AND WILLIAMSBURG COUNTY.
ELSEWHERE...MID 50S SHOULD PREDOMINATE.
RADAR IMAGERY SHOWS A PATCH OF LIGHT RAIN SITUATED IN THE ZONE OF
STRONGEST ISENTROPIC LIFT NEAR AND JUST EAST OF BALD HEAD ISLAND.
THIS SHOULD SHIFT NORTH OVER THE NEXT FEW HOURS BUT WILL LARGELY
DISSIPATE THIS AFTERNOON. OTHERWISE DRY CONDITIONS SHOULD CONTINUE.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 330 AM TUESDAY...DEVELOPING LOW PRESSURE SYSTEM OVER THE TEXAS
GULF COAST WILL TRACK NORTH TOWARD THE GREAT LAKES THROUGH THE
PERIOD. AS THE MID TO UPPER LOW DEEPENS OVER THE MID WEST...THE
RIDGE BECOMES MORE AMPLIFIED UP THROUGH THE SOUTHEAST COAST.
MODELS STILL SHOWING H5 HEIGHTS REACHING UP NEAR 588 DEM BY THURS
MORNING. WAA WILL BRING 850 TEMPS UP CLOSE TO 12C BY THURS BUT A
SHALLOW COOLER ON SHORE FLOW WILL EXIST AT THE SURFACE THROUGH
MID WEEK. INTERESTING SCENARIO AS COASTAL TROUGH WILL EXIST UP
THROUGH THE COASTAL CAROLINAS WITH COOLER NE FLOW INLAND AND
SOUTHEAST FLOW OFF SHORE REACHING THE COAST. THIS COASTAL TROUGH
WILL PROVIDE FOCUS FOR CLOUDS AND SOME PCP MAINLY TO THE SOUTH
THROUGH WEDNESDAY WHILE HIGH PRESSURE TO THE NORTH WILL PUSH A
BACKDOOR COLD FRONT INTO NORTH CAROLINA OVERNIGHT WED. THE GFS SHOWS
THIS BOUNDARY MAKING IT INTO LOCAL CWA BY THURS MORNING BUT THEN
RETURNING NORTH AS WARM FRONT. THIS MAY REINFORCE SHALLOW COOLER
AIR BRIEFLY AT THE SURFACE WHILE WINDS ALOFT INCREASE OUT OF THE
SOUTH AS STORM SYSTEM OVER THE MID WEST STRENGTHENS. EXPECT DECENT
AMOUNT OF LOW LEVEL CLOUDS THROUGH WED BUT SUBSIDENCE AND DRY AIR
THROUGH THE MID LEVELS SHOULD PREVENT MUCH IN THE WAY OF PCP UNTIL
LATE WED INTO THURS WHEN COASTAL TROUGH/WARM FRONT MAKES PROGRESS
INLAND AND NORTH. WILL KEEP BEST CHC OF MEASURABLE PCP AND
HIGHEST QPF DURING THURS. SHOULD SEE AN END TO MOST OF THE PCP
HEADING INTO THURS EVENING AS BEST LIFT SHIFTS NORTH OF AREA AS
WARM FRONT GETS PULLED NORTH AS STORM SYSTEM MOVES UP INTO THE
GREAT LAKES. OVERALL WILL SEE CLOUDS THROUGH MOST OF THE PERIOD
AND BEST CHC OF PCP OVERNIGHT WED INTO EARLY THURS.
TEMPS MAY BE A BIT TRICKY WITH CLOUDS AND PCP BEING OFFSET BY WAA
AND RIDGE BUILDING ALOFT WITH H5 HEIGHT INCREASES. THEN THE
BACKDOOR COLD FRONT MAY PROVIDE ANOTHER BURST OF VERY SHALLOW COOL
AIR FOR THURS MORNING BEFORE WARM FRONT MOVES NORTH OF AREA.
EXPECT MAX TEMPS UP INTO THE 60S AND LOWS REMAINING CLOSE TO 50 OR
ABOVE.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 3 AM TUESDAY...STRONG RIDGE BUILDING UP FROM THE BAHAMAS
UP THROUGH THE SOUTHEAST WILL BECOME TEMPORARILY DISRUPTED EARLY
FRIDAY AS IT TRACKS ACROSS THE CAROLINAS. ONCE THIS SHORTWAVE
CLEARS THE COAST IT WILL PUSH A COLD FRONT FARTHER EAST AWAY FROM
AREA ALLOWING HIGH PRESSURE TO DOMINATE THROUGH THE WEEKEND INTO
EARLY NEXT WEEK. THE RIDGE AXIS WILL RIDE UP RIGHT ALONG THE
SOUTHEAST COAST WITH CENTER OF THE SURFACE HIGH DISPLACED TO THE
EAST. THIS WILL PRODUCE A DEEP W-SW RETURN FLOW THROUGH MOST OF
THE PERIOD WITH PLENTY OF SUBSIDENCE AND DRY AIR THROUGH THE MID
LEVELS OF THE ATMOSPHERE. SOME LOW LEVEL MOISTURE SHOULD PRODUCE
SOME CLOUDS THROUGH THE PERIOD.
H5 HEIGHTS REMAIN AROUND 585 DEM AS RIDGE HOLDS ON TIGHT THROUGH THE
WEEKEND. 850 TEMPS HOLD UP TO 13 TO 14 C IN WAA INTO EARLY NEXT
WEEK. OVERALL EXPECT TEMPS TO BE WELL ABOVE NORMAL WITH AFTERNOON
HIGHS INTO THE 70S AND OVERNIGHT LOWS CLOSE TO NORMAL HIGHS FOR
THIS TIME OF YEAR...IN THE MID 50S.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 12Z...VFR/MVFR CIGS ACROSS THE AREA THIS MORNING AS SATELLITE
IMAGERY DEPICTS PLENTY OF LOW-LEVEL CLOUD COVER ASSOCIATED WITH A
COASTAL TROUGH. MOIST RETURN FLOW AROUND THE HIGH PRESSURE CENTERED
OFFSHORE WILL KEEP THE LOW CLOUDS AROUND THROUGH THIS TAF PERIOD. IT
APPEARS THAT LOW VFR CIGS WILL BE MOST PREVALENT ACROSS THE AREA
TODAY...ALTHOUGH SOME MVFR CIGS ARE POSSIBLE AS WELL. COULD SEE SOME
ISOLATED DRIZZLE ALONG THE COAST...BUT DECIDED IT WAS NOT WORTH
MENTIONING IN TAFS. EXPECT EAST WINDS AOB 8 KNOTS TODAY...BECOMING
LIGHT/CALM OVERNIGHT. MODEL SOUNDINGS AND GUIDANCE BOTH SUPPORT A
FOG/STRATUS EVENT OVERNIGHT WITH ABUNDANT LOW-LEVEL MOISTURE IN
PLACE ACROSS THE REGION. INCLUDED MVFR CIGS/VSBYS AFTER MIDNIGHT AT
ALL TERMINALS...AND IFR CONDITIONS COULD DEVELOP TOWARDS THE END OF
THE TAF PERIOD.
EXTENDED OUTLOOK...POSSIBLE MVFR/IFR CIGS WEDNESDAY AND THURSDAY.
SLIGHT CHANCE OF SHOWERS LATE WEDNESDAY INTO THURSDAY. VFR
DEVELOPING FRIDAY AND PERSISTING THROUGH SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM TUESDAY...BASED ON DATA FROM THE FRYING PAN SHOALS BUOY
SHOWING A SOUTHEAST WIND AND 66 DEGREE AIR TEMPERATURES...THE
COASTAL TROUGH LIES JUST TO THEIR WEST. ALL OTHER BUOY AND COASTAL
LOCATIONS HAVE MUCH COLDER AIR TEMPERATURES WITH NORTH TO NORTHEAST
WINDS. MODEL CONSENSUS IS THIS TROUGH SHOULD WEAKEN THIS AFTERNOON
AND ESPECIALLY TONIGHT AS THE HIGH ALONG THE MID-ATLANTIC COAST
NUDGES BACK TO THE SOUTH. RADAR SHOWS SOME PATCHY LIGHT RAIN JUST
EAST OF CAPE FEAR CURRENTLY. THIS PRECIPITATION SHOULD MOVE SLOWLY
NORTH THIS MORNING POTENTIALLY AFFECTING THE COASTAL WATERS NEAR
CAROLINA BEACH BEFORE DISSIPATING THIS AFTERNOON.
THE SURGE OF STRONG NORTH-NORTHEAST WINDS EARLIER THIS MORNING IS
DIMINISHING AND BY THIS AFTERNOON WIND SPEEDS SHOULD REMAIN BELOW 15
KNOTS. SEAS HAVE ALSO STARTED DIMINISHING WITH 5 FT SEAS AT THE
FRYING PAN SHOALS BUOY AND 4 FT AT THE NEARSHORE WRIGHTSVILLE BEACH
BUOY. THE EXERCISE CAUTION HEADLINE WILL CONTINUE FOR THE NC WATERS
THROUGH 11 AM.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 3 AM TUESDAY...COASTAL TROUGH ON WED BECOMES DAMPENED AS
HIGH PRESSURE PUSHES A BACK DOOR COLD FRONT SOUTH. SHOULD SEE
LIGHT E-SE FLOW THROUGH WED 10 KTS OR LESS. FLOW MAY SHIFT AROUND
TO THE NE BRIEFLY EARLY THURS AS WEAK BACKDOOR FRONT MOVES INTO
AREA BUT THIS WILL MOVE BACK NORTH AS WARM FRONT ON THURSDAY WITH
AN INCREASING SOUTHERLY FLOW DEVELOPING THURS NIGHT. SEAS WILL
BASICALLY REMAIN 3 FT OR LESS THROUGH THURS MORNING AND THEN WILL
RISE UP TO 3 TO 5 FT IN INCREASING SOUTHERLY PUSH LATE THURS INTO
FRI.
LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 3 AM TUESDAY...SOUTHERLY FLOW AROUND 15 KTS WILL VEER TO THE
SOUTHWEST AND LIGHTEN THROUGH THE FIRST HALF OF THE WEEKEND AS HIGH
PRESSURE OVER THE LOCAL WATERS SHIFTS SOUTH AND WEST. OVERALL
GRADIENT WILL RELAX THROUGH SATURDAY. EXPECT WINDS TO LIGHTEN TO
10 KTS OR LESS BY LATE SAT WITH SEAS DIMINISHING FROM 3-5 FEET ON
FRI DOWN TO 2 TO 3 FT BY SAT NIGHT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
645 AM EST TUE JAN 8 2013
.SYNOPSIS...
HIGH PRESSURE WILL LINGER OVER THE AREA THROUGH WEDNESDAY. A
BACKDOOR COLD FRONT WILL PUSH INTO THE REGION THURSDAY... THEN
RETURN NORTH AS A WARM FRONT LATE FRIDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 305 AM TUESDAY...
TODAY...
A 1030MB SURFACE HIGH CENTERED OVER THE VA TIDEWATER AREA EXTENDS
SOUTHWEST ACROSS CENTRAL NC THIS MORNING. ALOFT...A WEAK
DISTURBANCES WITHIN THE BROAD SUBTROPICAL RIDGE IS MOVING OVER THE
CWA...WITH THE ASSOCIATED CIRRUS CURRENTLY EXITING THE NORTHERN
COASTAL PLAIN. BENEATH A STRONG AND DRY SUBSIDENCE INVERSION AT
900MB...INCREASINGLY VEERED LOW LEVEL FLOW IS BEGINNING TO ADVECT
MOISTURE INLAND. IR IMAGERY SHOWS STRATUS EXPANDING FROM COASTAL
CAROLINA NORTHWESTWARD INTO THE SOUTHERN COASTAL PLAIN AND
SANDHILLS. THE HRRR MOISTURE FIELDS...WHICH APPEAR TO HAVE A GOOD
HANDLE ON THIS CLOUD COVER...SHOW MOISTURE SPREADING NORTH THROUGH
THE PIEDMONT THIS MORNING. IF THE CLOUD COVER IS AS THICK AND
WIDESPREAD AS THE NAM AND RAP FORECAST SOUNDINGS SHOW....HIGHS WILL
BE A GOOD 5-7 DEGREES BELOW FULL SUN THICKNESS VALUES TODAY. PREFER
THE COOLER MET MOS BASED ON CURRENT TRENDS...51-58 WEST TO EAST.
OTHERWISE..NO SENSIBLE WEATHER IMPACTS TODAY AS MOISTURE IS MUCH TOO
SHALLOW AND THE MID LEVELS TOO DRY FOR ANY PRECIP.
TONIGHT...
CONTINUATION OF THE RETURN FLOW AROUND OF THE ELONGATING SURFACE
RIDGE AXIS WILL LEAD TO STRATUS AGAIN OVERNIGHT. FORECAST SOUNDINGS
ARE SUPPORTED BY HIGH SREF PROBABILITIES OF LOW CEILINGS OVER THE
WESTERN PIEDMONT. HIGH CLOUDS SHOULD ALSO BE ON THE INCREASE AS
MOISTURE STREAMS IN FROM THE SOUTHWEST AHEAD OF AN UPPER LOW MOVING
SLOWLY ACROSS THE TX/MEXICO BORDER. MOSTLY CLOUDY SKIES SHOULD
LIMIT ANY FOG POTENTIAL...BUT WITH DEWPOINTS CREEPING UP INTO THE
LOWER 40S AND WEAK WINDS WITHIN THE SURFACE RIDGE AXIS...THERE COULD
BE SOME PATCHY FOG IN THE SOUTH AND EAST LATE TONIGHT. LOWS 37-42.
WEDNESDAY...
THE AIRMASS OVER CENTRAL NC WILL CONTINUE TO MOISTEN WEDNESDAY AS
HIGH PRESSURE LINGERS OFF THE COAST AND RETURN FLOW PERSISTS. AN
UNSEASONABLY STRONG SUBTROPICAL RIDGE WILL HOLD OVER THE SOUTHEAST
US...WHILE ONE SHORTWAVE CROSSES THE GREAT LAKES REGION AND THE
AFOREMENTIONED UPPER LOW OVER TX BEGINS TO LIFT NORTH THROUGH THE
SOUTHERN PLAINS. MODELS GENERATE SOME VERY LIGHT QPF LATE IN THE DAY
ACROSS THE SOUTHERN CWA...BUT THIS APPEARS TO BE OVERDONE GIVEN THE
LACK OF FORCING. WILL MAINTAIN A DRY FORECAST FOR WEDNESDAY. LOW
LEVEL THICKNESSES APPROACH 1370M BY WEDNESDAY AFTERNOON..BUT AS PW
VALUES RISE TO NEAR ONE INCH... THERE SHOULD AGAIN BE SOME IMPACT OF
CLOUD COVER ON HEATING. HIGHS 61-66.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 300 AM TUESDAY...
A HYBRID COLD AIR DAMMING EVENT LIKELY LATE THURSDAY INTO FRIDAY...
THE EVOLVING PATTERN CONSISTING OF A DEEP WEST-CENTRAL U.S. TROUGH
AND STRONGLY RISING UPPER HEIGHTS FROM THE CARIBBEAN THROUGH THE
SOUTHEAST U.S. LATE WEEK INTO THE WEEKEND WILL EVENTUALLY MEAN A
WARM AND MOSTLY DRY PERIOD FOR OUR REGION THIS WEEKEND. BEFORE THAT
OCCURS... A HYBRID CAD EVENT IS EXPECTED TO DEVELOP OVER THE
PIEDMONT DAMMING REGION THURSDAY AND LAST INTO FRIDAY.
THE WARMING ASSOCIATED WITH RISING HEIGHTS ALOFT WILL INITIALLY BE
OFFSET BY THE STRONG (1035+ MB) SURFACE HIGH THAT IS EXPECTED TO
BUILD EAST FROM THE OHIO VALLEY TO THE NEW ENGLAND COAST THURSDAY
INTO EARLY FRIDAY. THE STRENGTH AND POSITION OF THIS HIGH PRESSURE
IS VERY FAVORABLE FOR CAD DEEP INTO OUR REGION. THE HIGH IS FORECAST
TO BE PROGRESSIVE AS THE MID/UPPER FLOW OVER THE NE US BECOMES
CONFLUENT BY THE WEEKEND... MAKING THIS A HYBRID CAD EVENT... AND
ONE THAT WILL ERODE A BIT MORE QUICKLY THAN CLASSICAL CAD EPISODES.
INITIALLY ON THURSDAY... THE HIGH IS EXPECTED TO BUILD SOUTH... DOWN
THE EASTERN SEABOARD... WHEN THE SOUTHERN PLAINS STORM SYSTEM IS
FORECAST TO TRACK NE THROUGH THE OHIO VALLEY THU NIGHT. WARM MOIST
AIR IS EXPECTED TO OVERRUN THE COOL STABLE LAYER EAST OF THE
MOUNTAINS THU NIGHT AND FRIDAY... WITH AREAS OF RAIN
DEVELOPING/OVERSPREADING THE REGION. THIS WILL ALLOW THE CAD EVENT
TO SHAPE UP THURSDAY NIGHT INTO FRIDAY.
THE EVENTUAL DEPTH AND DURATION OF THE CAD SHOULD LARGELY BE DRIVEN
BY THE AMOUNT OF QPF THOSE PERIODS INTO THE COOL STABLE AIR...
LOCKING THE CAD IN PLACE. THE CURRENT FAVORED BLEND OF THE LATEST
GFS/EC OPERATIONAL MODELS AND EC ENSEMBLES INDICATE THE QPF TO
REACH THE CRITICAL 0.12 TO 0.25 THRESHOLD IN THE PIEDMONT DAMMING
REGION... SUFFICIENT TO LOCK IN THE CAD THURSDAY NIGHT INTO EARLY
FRIDAY. IF THIS IS REALIZED... THIS WILL DELAY THE THE WARM FRONT
FROM SURGING THROUGH CENTRAL NC ON FRIDAY MORNING. IT WOULD TAKE
MUCH OF THE DAY FOR THE DAMMING (PARTICULARLY THE RESIDUAL AFFECTS -
LOWS CLOUDS/FOG/DRIZZLE) TO ERODE. CURRENT THINKING IS THAT THE
PIEDMONT TRIAD REGION MAY VERY WELL HAVE CAD AFFECTS INTO SAT
MORNING.
SENSIBLE WEATHER...
PARTLY CLOUDY WEDNESDAY NIGHT WITH LOWS IN THE UPPER 30S TO MID 40S.
THURSDAY... INCREASING CLOUDS NE... MOSTLY CLOUDY TO CLOUDY WEST.
WINDS BECOMING ENE. HIGHS IN THE 50S TO LOWER 60S SE. THURSDAY NIGHT
AND EARLY FRIDAY... RAIN LIKELY NW AND A CHANCE SE. COOL IN THE
DAMMING REGION. LOWS IN THE 40S. LINGERING LOW CLOUDS AND LIGHT
RAIN/DRIZZLE FRIDAY IN THE DAMMING REGION. BECOMING MOSTLY CLOUDY
SE/WARMER. HIGHS 55 NW TO UPPER 60S SE. PARTLY CLOUDY TO CLOUDY
FRIDAY NIGHT. WARMER. LOWS 45-55. AREAS OF FOG/LOW CLOUDS AGAIN
LIKELY NW.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 300 TUESDAY...
THE LATEST MODELS SUPPORT THE SLOWER TIMING OF THE COLD FRONT BY
EARLY NEXT WEEK. THIS WILL ENSURE A WEEKEND OF WARM DRY WEATHER WITH
TEMPS 20 TO 30 DEGREES ABOVE NORMAL. WE WILL HOLD OFF MENTION OF ANY
SHOWERS UNTIL SUNDAY NIGHT OR MONDAY.
BECOMING PARTLY CLOUDY SATURDAY. BREEZY AND WARMER. HIGHS IN THE
UPPER 60S TO MID 70S. LOWS SAT NIGHT IN THE 50S (AVERAGE HIGHS ARE
48-53). SUNDAY... PARTLY SUNNY. HIGHS LOWER TO MID 70S. MONDAY...
MOSTLY CLOUDY WITH A CHANCE OF SHOWERS. HIGHS IN THE 60S TO LOWER
70S SE.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 645 AM TUESDAY...
WITH HIGH PRESSURE NOW SETTLING EAST ALONG THE COAST...EASTERLY LOW
LEVEL WINDS ARE BEGINNING TO USHER MOISTURE INLAND ACROSS THE
CAROLINAS. STRATOCU HAS SPREAD FROM SC NORTH ACROSS ALMOST ALL OF
CENTRAL NC. CEILINGS GENERALLY VARY FROM 5000FT NORTH TO 3000FT
SOUTH. BASED ON SATELLITE TRENDS AND HRRR MODEL MOISTURE
FIELDS...MVFR CEILINGS ARE MOSTLY LIKELY IN THE NEXT 3-6 HOURS AT
KFAY/KGSO/KINT. MVFR CEILINGS CANNOT BE RULED OUT AT KRDU AND/OR
KRWI..BUT CONFIDENCE IS MUCH LOWER AT THESE SITES. WHILE SOME
IMPROVEMENT IS FORECAST THIS AFTERNOON...THIS MOISTURE IS TRAPPED
BENEATH A STRONG SUBSIDENCE INVERSION LOCATED NEAR 5000FT...SO
CEILINGS ARE LIKELY TO REMAIN NEAR MVFR LEVELS THROUGHOUT THE DAY.
TONIGHT...AS WINDS CONTINUE TO SHIFT AROUND TO
SOUTH-SOUTHWESTERLY...THERE IS A BETTER CHANCE OF MVFR AND/OR IFR
CEILINGS..ESPECIALLY AT WESTERN TERMINALS (KGSO/KINT).
OUTLOOK...
AN EXTENDED PERIOD OF CLOUDINESS WITH SUB-VFR CONDITIONS IN LIGHT
RAIN WILL THEN BE POSSIBLE THURSDAY AND FRIDAY AS A WARM FRONT
APPROACHES FROM THE SOUTH-SOUTHWEST.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...SMITH
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
305 AM EST TUE JAN 8 2013
.SYNOPSIS...
HIGH PRESSURE WILL LINGER OVER THE AREA THROUGH WEDNESDAY. A
BACKDOOR COLD FRONT WILL PUSH INTO THE REGION THURSDAY... THEN
RETURN NORTH AS A WARM FRONT LATE FRIDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 305 AM TUESDAY...
TODAY...
A 1030MB SURFACE HIGH CENTERED OVER THE VA TIDEWATER AREA EXTENDS
SOUTHWEST ACROSS CENTRAL NC THIS MORNING. ALOFT...A WEAK
DISTURBANCES WITHIN THE BROAD SUBTROPICAL RIDGE IS MOVING OVER THE
CWA...WITH THE ASSOCIATED CIRRUS CURRENTLY EXITING THE NORTHERN
COASTAL PLAIN. BENEATH A STRONG AND DRY SUBSIDENCE INVERSION AT
900MB...INCREASINGLY VEERED LOW LEVEL FLOW IS BEGINNING TO ADVECT
MOISTURE INLAND. IR IMAGERY SHOWS STRATUS EXPANDING FROM COASTAL
CAROLINA NORTHWESTWARD INTO THE SOUTHERN COASTAL PLAIN AND
SANDHILLS. THE HRRR MOISTURE FIELDS...WHICH APPEAR TO HAVE A GOOD
HANDLE ON THIS CLOUD COVER...SHOW MOISTURE SPREADING NORTH THROUGH
THE PIEDMONT THIS MORNING. IF THE CLOUD COVER IS AS THICK AND
WIDESPREAD AS THE NAM AND RAP FORECAST SOUNDINGS SHOW....HIGHS WILL
BE A GOOD 5-7 DEGREES BELOW FULL SUN THICKNESS VALUES TODAY. PREFER
THE COOLER MET MOS BASED ON CURRENT TRENDS...51-58 WEST TO EAST.
OTHERWISE..NO SENSIBLE WEATHER IMPACTS TODAY AS MOISTURE IS MUCH TOO
SHALLOW AND THE MID LEVELS TOO DRY FOR ANY PRECIP.
TONIGHT...
CONTINUATION OF THE RETURN FLOW AROUND OF THE ELONGATING SURFACE
RIDGE AXIS WILL LEAD TO STRATUS AGAIN OVERNIGHT. FORECAST SOUNDINGS
ARE SUPPORTED BY HIGH SREF PROBABILITIES OF LOW CEILINGS OVER THE
WESTERN PIEDMONT. HIGH CLOUDS SHOULD ALSO BE ON THE INCREASE AS
MOISTURE STREAMS IN FROM THE SOUTHWEST AHEAD OF AN UPPER LOW MOVING
SLOWLY ACROSS THE TX/MEXICO BORDER. MOSTLY CLOUDY SKIES SHOULD
LIMIT ANY FOG POTENTIAL...BUT WITH DEWPOINTS CREEPING UP INTO THE
LOWER 40S AND WEAK WINDS WITHIN THE SURFACE RIDGE AXIS...THERE COULD
BE SOME PATCHY FOG IN THE SOUTH AND EAST LATE TONIGHT. LOWS 37-42.
WEDNESDAY...
THE AIRMASS OVER CENTRAL NC WILL CONTINUE TO MOISTEN WEDNESDAY AS
HIGH PRESSURE LINGERS OFF THE COAST AND RETURN FLOW PERSISTS. AN
UNSEASONABLY STRONG SUBTROPICAL RIDGE WILL HOLD OVER THE SOUTHEAST
US...WHILE ONE SHORTWAVE CROSSES THE GREAT LAKES REGION AND THE
AFOREMENTIONED UPPER LOW OVER TX BEGINS TO LIFT NORTH THROUGH THE
SOUTHERN PLAINS. MODELS GENERATE SOME VERY LIGHT QPF LATE IN THE DAY
ACROSS THE SOUTHERN CWA...BUT THIS APPEARS TO BE OVERDONE GIVEN THE
LACK OF FORCING. WILL MAINTAIN A DRY FORECAST FOR WEDNESDAY. LOW
LEVEL THICKNESSES APPROACH 1370M BY WEDNESDAY AFTERNOON..BUT AS PW
VALUES RISE TO NEAR ONE INCH... THERE SHOULD AGAIN BE SOME IMPACT OF
CLOUD COVER ON HEATING. HIGHS 61-66.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 300 AM TUESDAY...
A HYBRID COLD AIR DAMMING EVENT LIKELY LATE THURSDAY INTO FRIDAY...
THE EVOLVING PATTERN CONSISTING OF A DEEP WEST-CENTRAL U.S. TROUGH
AND STRONGLY RISING UPPER HEIGHTS FROM THE CARIBBEAN THROUGH THE
SOUTHEAST U.S. LATE WEEK INTO THE WEEKEND WILL EVENTUALLY MEAN A
WARM AND MOSTLY DRY PERIOD FOR OUR REGION THIS WEEKEND. BEFORE THAT
OCCURS... A HYBRID CAD EVENT IS EXPECTED TO DEVELOP OVER THE
PIEDMONT DAMMING REGION THURSDAY AND LAST INTO FRIDAY.
THE WARMING ASSOCIATED WITH RISING HEIGHTS ALOFT WILL INITIALLY BE
OFFSET BY THE STRONG (1035+ MB) SURFACE HIGH THAT IS EXPECTED TO
BUILD EAST FROM THE OHIO VALLEY TO THE NEW ENGLAND COAST THURSDAY
INTO EARLY FRIDAY. THE STRENGTH AND POSITION OF THIS HIGH PRESSURE
IS VERY FAVORABLE FOR CAD DEEP INTO OUR REGION. THE HIGH IS FORECAST
TO BE PROGRESSIVE AS THE MID/UPPER FLOW OVER THE NE US BECOMES
CONFLUENT BY THE WEEKEND... MAKING THIS A HYBRID CAD EVENT... AND
ONE THAT WILL ERODE A BIT MORE QUICKLY THAN CLASSICAL CAD EPISODES.
INITIALLY ON THURSDAY... THE HIGH IS EXPECTED TO BUILD SOUTH... DOWN
THE EASTERN SEABOARD... WHEN THE SOUTHERN PLAINS STORM SYSTEM IS
FORECAST TO TRACK NE THROUGH THE OHIO VALLEY THU NIGHT. WARM MOIST
AIR IS EXPECTED TO OVERRUN THE COOL STABLE LAYER EAST OF THE
MOUNTAINS THU NIGHT AND FRIDAY... WITH AREAS OF RAIN
DEVELOPING/OVERSPREADING THE REGION. THIS WILL ALLOW THE CAD EVENT
TO SHAPE UP THURSDAY NIGHT INTO FRIDAY.
THE EVENTUAL DEPTH AND DURATION OF THE CAD SHOULD LARGELY BE DRIVEN
BY THE AMOUNT OF QPF THOSE PERIODS INTO THE COOL STABLE AIR...
LOCKING THE CAD IN PLACE. THE CURRENT FAVORED BLEND OF THE LATEST
GFS/EC OPERATIONAL MODELS AND EC ENSEMBLES INDICATE THE QPF TO
REACH THE CRITICAL 0.12 TO 0.25 THRESHOLD IN THE PIEDMONT DAMMING
REGION... SUFFICIENT TO LOCK IN THE CAD THURSDAY NIGHT INTO EARLY
FRIDAY. IF THIS IS REALIZED... THIS WILL DELAY THE THE WARM FRONT
FROM SURGING THROUGH CENTRAL NC ON FRIDAY MORNING. IT WOULD TAKE
MUCH OF THE DAY FOR THE DAMMING (PARTICULARLY THE RESIDUAL AFFECTS -
LOWS CLOUDS/FOG/DRIZZLE) TO ERODE. CURRENT THINKING IS THAT THE
PIEDMONT TRIAD REGION MAY VERY WELL HAVE CAD AFFECTS INTO SAT
MORNING.
SENSIBLE WEATHER...
PARTLY CLOUDY WEDNESDAY NIGHT WITH LOWS IN THE UPPER 30S TO MID 40S.
THURSDAY... INCREASING CLOUDS NE... MOSTLY CLOUDY TO CLOUDY WEST.
WINDS BECOMING ENE. HIGHS IN THE 50S TO LOWER 60S SE. THURSDAY NIGHT
AND EARLY FRIDAY... RAIN LIKELY NW AND A CHANCE SE. COOL IN THE
DAMMING REGION. LOWS IN THE 40S. LINGERING LOW CLOUDS AND LIGHT
RAIN/DRIZZLE FRIDAY IN THE DAMMING REGION. BECOMING MOSTLY CLOUDY
SE/WARMER. HIGHS 55 NW TO UPPER 60S SE. PARTLY CLOUDY TO CLOUDY
FRIDAY NIGHT. WARMER. LOWS 45-55. AREAS OF FOG/LOW CLOUDS AGAIN
LIKELY NW.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 300 TUESDAY...
THE LATEST MODELS SUPPORT THE SLOWER TIMING OF THE COLD FRONT BY
EARLY NEXT WEEK. THIS WILL ENSURE A WEEKEND OF WARM DRY WEATHER WITH
TEMPS 20 TO 30 DEGREES ABOVE NORMAL. WE WILL HOLD OFF MENTION OF ANY
SHOWERS UNTIL SUNDAY NIGHT OR MONDAY.
BECOMING PARTLY CLOUDY SATURDAY. BREEZY AND WARMER. HIGHS IN THE
UPPER 60S TO MID 70S. LOWS SAT NIGHT IN THE 50S (AVERAGE HIGHS ARE
48-53). SUNDAY... PARTLY SUNNY. HIGHS LOWER TO MID 70S. MONDAY...
MOSTLY CLOUDY WITH A CHANCE OF SHOWERS. HIGHS IN THE 60S TO LOWER
70S SE.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1240 AM TUESDAY...
WITH HIGH PRESSURE NOW SETTLING EAST ALONG THE COAST...EASTERLY LOW
LEVEL WINDS ARE BEGINNING TO USHER MOISTURE INLAND ACROSS THE
CAROLINAS. STRATUS HAS DEVELOPED OVER THE SC COASTAL AREAS AND IS
STARTING TO SPREAD INLAND TO THE WEST-NORTHWEST. SATELLITE TRENDS
WOULD SUGGEST THIS MOISTURE COULD REACH KFAY BY 12Z...AND HRRR MODEL
CEILING FORECASTS SUPPORT THIS. THUS...THERE IS INCREASING
CONFIDENCE THAT MVFR...OR NEAR MVFR CEILINGS WILL MOVE DEVELOP AT
KFAY BY AROUND 12 AND KRDU/KRWI BY 15Z. WILL ALSO CONTINUE A LOW
CONFIDENCE CHANCE OF LOCALIZED FOG/STRATUS AT KRWI THROUGH 12Z.
DAYTIME HEATING MAY CAUSE THE CLOUD DECK TO SCATTER A BIT BY THIS
AFTERNOON...BUT THERE SHOULD STILL BE ENOUGH MOISTURE BELOW A STRONG
SUBSIDENCE INVERSION TO KEEP CONDITIONS ON AT LEAST THE THE EDGE OF
MVFR. FURTHER WEST AT KGSO/KINT...MVFR CONDITIONS ARE NOT RULED
OUT...BUT CONFIDENCE IS MUCH LOWER.
TONIGHT...AS WINDS CONTINUE TO SHIFT AROUND TO
SOUTH-SOUTHWESTERLY...THERE IS A BETTER CHANCE OF MVFR AND/OR IFR
CEILINGS..ESPECIALLY AT WESTERN TERMINALS (KGSO/KINT)
OUTLOOK...
AN EXTENDED PERIOD OF CLOUDINESS WITH SUB-VFR CONDITIONS IN LIGHT
RAIN WILL THEN BE POSSIBLE THURSDAY AND FRIDAY AS A WARM FRONT
APPROACHES FROM THE SOUTH-SOUTHWEST.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...SMITH
SHORT TERM...BADGETT
LONG TERM...BADGETT
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
300 AM EST TUE JAN 8 2013
.SYNOPSIS...
HIGH PRESSURE WILL LINGER OVER THE AREA THROUGH WEDNESDAY. A
BACKDOOR COLD FRONT WILL PUSH INTO THE REGION THURSDAY... THEN
RETURN NORTH AS A WARM FRONT LATE FRIDAY.
&&
.NEAR TERM /THROUGH TUESDAY/...
AS OF 850 PM MONDAY...
TONIGHT:
HIGH PRESSURE WILL CONTINUE TO SHIFT EASTWARD OVERNIGHT KEEPING
SKIES MOSTLY CLEAR. CURRENT SATELLITE AND WATER VAPOR TRENDS SHOW
AN AREA OF HIGH LEVEL MOISTURE BRAINING SOME CLOUDS OVER UPSTATE
SOUTH CAROLINA THAT MAY AFFECT CENTRAL NC OVER THE NEXT SEVERAL
HOURS. ANY LINGERING CLOUDINESS ASIDE...LOW TEMPERATURE SHOULD BE
ABLE TO DROP INTO THE UPPER 20S IN MOST LOCATIONS TO NEAR 30 IN THE
SOUTH WHERE SOME MID LEVEL STRATUS MAY CREEP IN FROM THE SOUTHEAST
JUST BEFORE SUNRISE. FOR THE MOST PART DEWPOINT DEPRESSIONS SHOULD
BE LARGE ENOUGH TO KEEP FOG OR LOW STRATUS FROM FORMING BUT THERE IS
AN OUTSIDE CHANCE THAT IT COULD FORM AT KRWI DURING THE EARLY
MORNING HOURS. WINDS WILL BE LARGELY CALM OVERNIGHT BUT WILL
GRADUALLY SHIFT TO A SOUTHWESTERLY DIRECTION AS THE HIGH PUSHES OUT
TO SEA. -ELLIS
TUESDAY:
LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE ACROSS THE AREA ALONG
WITH A WEAK UPPER LEVEL DISTURBANCE MOVING ACROSS THE AREA IN THE SW
FLOW. NOT EXPECTING ANY PRECIP AS WE WILL HAVE A LOT OF DRY MID
LEVEL AIR AND NOT ENOUGH ISENTROPIC LIFT AND MOISTURE IN THE LOW
LEVELS. LOW LEVEL MOISTURE RETURN SHOULD ALLOW FOR AT LEAST PARTLY
SUNNY TO EVEN MOSTLY CLOUDY SKIES ACROSS A GOOD PORTION OF THE AREA
TUESDAY... WITH THE EARLIEST AND MOST CLOUDS ACROSS THE WEST AND
SOUTH/SOUTHWEST... WITH THE LEAST IN THE NORTHEAST. AFTERNOON LOW
LEVEL THICKNESS VALUES ARE PROGGED TO BE AROUND 15 METERS HIGHER
THAN TODAY. HOWEVER... THANKS TO THE INCREASE IN CLOUD COVER HIGH
TEMPS OVER MOST OF THE AREA WILL NOT BE ABLE TO REACH THEIR FULL SUN
HIGHS.... ESPECIALLY IN THE WEST... WHICH IS SHOWN IN THE
STATISTICAL GUIDANCE WELL. THUS... WILL GO WITH HIGH TEMPS RANGING
FROM THE LOWER 50S WEST TO UPPER 50S/NEAR 60 EAST/SOUTHEAST. -BSD
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
AS IF 300 AM TUESDAY...
A HYBRID COLD AIR DAMMING EVENT LIKELY LATE THURSDAY INTO FRIDAY...
THE EVOLVING PATTERN CONSISTING OF A DEEP WEST-CENTRAL U.S. TROUGH
AND STRONGLY RISING UPPER HEIGHTS FROM THE CARIBBEAN THROUGH THE
SOUTHEAST U.S. LATE WEEK INTO THE WEEKEND WILL EVENTUALLY MEAN A
WARM AND MOSTLY DRY PERIOD FOR OUR REGION THIS WEEKEND. BEFORE THAT
OCCURS... A HYBRID CAD EVENT IS EXPECTED TO DEVELOP OVER THE
PIEDMONT DAMMING REGION THURSDAY AND LAST INTO FRIDAY.
THE WARMING ASSOCIATED WITH RISING HEIGHTS ALOFT WILL INITIALLY BE
OFFSET BY THE STRONG (1035+ MB) SURFACE HIGH THAT IS EXPECTED TO
BUILD EAST FROM THE OHIO VALLEY TO THE NEW ENGLAND COAST THURSDAY
INTO EARLY FRIDAY. THE STRENGTH AND POSITION OF THIS HIGH PRESSURE
IS VERY FAVORABLE FOR CAD DEEP INTO OUR REGION. THE HIGH IS FORECAST
TO BE PROGRESSIVE AS THE MID/UPPER FLOW OVER THE NE US BECOMES
CONFLUENT BY THE WEEKEND... MAKING THIS A HYBRID CAD EVENT... AND
ONE THAT WILL ERODE A BIT MORE QUICKLY THAN CLASSICAL CAD EPISODES.
INITIALLY ON THURSDAY... THE HIGH IS EXPECTED TO BUILD SOUTH... DOWN
THE EASTERN SEABOARD... WHEN THE SOUTHERN PLAINS STORM SYSTEM IS
FORECAST TO TRACK NE THROUGH THE OHIO VALLEY THU NIGHT. WARM MOIST
AIR IS EXPECTED TO OVERRUN THE COOL STABLE LAYER EAST OF THE
MOUNTAINS THU NIGHT AND FRIDAY... WITH AREAS OF RAIN
DEVELOPING/OVERSPREADING THE REGION. THIS WILL ALLOW THE CAD EVENT
TO SHAPE UP THURSDAY NIGHT INTO FRIDAY.
THE EVENTUAL DEPTH AND DURATION OF THE CAD SHOULD LARGELY BE DRIVEN
BY THE AMOUNT OF QPF THOSE PERIODS INTO THE COOL STABLE AIR...
LOCKING THE CAD IN PLACE. THE CURRENT FAVORED BLEND OF THE LATEST
GFS/EC OPERATIONAL MODELS AND EC ENSEMBLES INDICATE THE QPF TO
REACH THE CRITICAL 0.12 TO 0.25 THRESHOLD IN THE PIEDMONT DAMMING
REGION... SUFFICIENT TO LOCK IN THE CAD THURSDAY NIGHT INTO EARLY
FRIDAY. IF THIS IS REALIZED... THIS WILL DELAY THE THE WARM FRONT
FROM SURGING THROUGH CENTRAL NC ON FRIDAY MORNING. IT WOULD TAKE
MUCH OF THE DAY FOR THE DAMMING (PARTICULARLY THE RESIDUAL AFFECTS -
LOWS CLOUDS/FOG/DRIZZLE) TO ERODE. CURRENT THINKING IS THAT THE
PIEDMONT TRIAD REGION MAY VERY WELL HAVE CAD AFFECTS INTO SAT
MORNING.
SENSIBLE WEATHER...
PARTLY CLOUDY WEDNESDAY NIGHT WITH LOWS IN THE UPPER 30S TO MID 40S.
THURSDAY... INCREASING CLOUDS NE... MOSTLY CLOUDY TO CLOUDY WEST.
WINDS BECOMING ENE. HIGHS IN THE 50S TO LOWER 60S SE. THURSDAY NIGHT
AND EARLY FRIDAY... RAIN LIKELY NW AND A CHANCE SE. COOL IN THE
DAMMING REGION. LOWS IN THE 40S. LINGERING LOW CLOUDS AND LIGHT
RAIN/DRIZZLE FRIDAY IN THE DAMMING REGION. BECOMING MOSTLY CLOUDY
SE/WARMER. HIGHS 55 NW TO UPPER 60S SE. PARTLY CLOUDY TO CLOUDY
FRIDAY NIGHT. WARMER. LOWS 45-55. AREAS OF FOG/LOW CLOUDS AGAIN
LIKELY NW.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 300 TUESDAY...
THE LATEST MODELS SUPPORT THE SLOWER TIMING OF THE COLD FRONT BY
EARLY NEXT WEEK. THIS WILL ENSURE A WEEKEND OF WARM DRY WEATHER WITH
TEMPS 20 TO 30 DEGREES ABOVE NORMAL. WE WILL HOLD OFF MENTION OF ANY
SHOWERS UNTIL SUNDAY NIGHT OR MONDAY.
BECOMING PARTLY CLOUDY SATURDAY. BREEZY AND WARMER. HIGHS IN THE
UPPER 60S TO MID 70S. LOWS SAT NIGHT IN THE 50S (AVERAGE HIGHS ARE
48-53). SUNDAY... PARTLY SUNNY. HIGHS LOWER TO MID 70S. MONDAY...
MOSTLY CLOUDY WITH A CHANCE OF SHOWERS. HIGHS IN THE 60S TO LOWER
70S SE.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1240 AM TUESDAY...
WITH HIGH PRESSURE NOW SETTLING EAST ALONG THE COAST...EASTERLY LOW
LEVEL WINDS ARE BEGINNING TO USHER MOISTURE INLAND ACROSS THE
CAROLINAS. STRATUS HAS DEVELOPED OVER THE SC COASTAL AREAS AND IS
STARTING TO SPREAD INLAND TO THE WEST-NORTHWEST. SATELLITE TRENDS
WOULD SUGGEST THIS MOISTURE COULD REACH KFAY BY 12Z...AND HRRR MODEL
CEILING FORECASTS SUPPORT THIS. THUS...THERE IS INCREASING
CONFIDENCE THAT MVFR...OR NEAR MVFR CEILINGS WILL MOVE DEVELOP AT
KFAY BY AROUND 12 AND KRDU/KRWI BY 15Z. WILL ALSO CONTINUE A LOW
CONFIDENCE CHANCE OF LOCALIZED FOG/STRATUS AT KRWI THROUGH 12Z.
DAYTIME HEATING MAY CAUSE THE CLOUD DECK TO SCATTER A BIT BY THIS
AFTERNOON...BUT THERE SHOULD STILL BE ENOUGH MOISTURE BELOW A STRONG
SUBSIDENCE INVERSION TO KEEP CONDITIONS ON AT LEAST THE THE EDGE OF
MVFR. FURTHER WEST AT KGSO/KINT...MVFR CONDITIONS ARE NOT RULED
OUT...BUT CONFIDENCE IS MUCH LOWER.
TONIGHT...AS WINDS CONTINUE TO SHIFT AROUND TO
SOUTH-SOUTHWESTERLY...THERE IS A BETTER CHANCE OF MVFR AND/OR IFR
CEILINGS..ESPECIALLY AT WESTERN TERMINALS (KGSO/KINT)
OUTLOOK...
AN EXTENDED PERIOD OF CLOUDINESS WITH SUB-VFR CONDITIONS IN LIGHT
RAIN WILL THEN BE POSSIBLE THURSDAY AND FRIDAY AS A WARM FRONT
APPROACHES FROM THE SOUTH-SOUTHWEST.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BSD
NEAR TERM...ELLIS/BSD
SHORT TERM...KC
LONG TERM...KC
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1240 AM EST TUE JAN 8 2013
.SYNOPSIS...
HIGH PRESSURE WILL LINGER OVER THE AREA THROUGH MIDWEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
AS OF 850 PM MONDAY...
TONIGHT:
HIGH PRESSURE WILL CONTINUE TO SHIFT EASTWARD OVERNIGHT KEEPING
SKIES MOSTLY CLEAR. CURRENT SATELLITE AND WATER VAPOR TRENDS SHOW
AN AREA OF HIGH LEVEL MOISTURE BRAINING SOME CLOUDS OVER UPSTATE
SOUTH CAROLINA THAT MAY AFFECT CENTRAL NC OVER THE NEXT SEVERAL
HOURS. ANY LINGERING CLOUDINESS ASIDE...LOW TEMPERATURE SHOULD BE
ABLE TO DROP INTO THE UPPER 20S IN MOST LOCATIONS TO NEAR 30 IN THE
SOUTH WHERE SOME MID LEVEL STRATUS MAY CREEP IN FROM THE SOUTHEAST
JUST BEFORE SUNRISE. FOR THE MOST PART DEWPOINT DEPRESSIONS SHOULD
BE LARGE ENOUGH TO KEEP FOG OR LOW STRATUS FROM FORMING BUT THERE IS
AN OUTSIDE CHANCE THAT IT COULD FORM AT KRWI DURING THE EARLY
MORNING HOURS. WINDS WILL BE LARGELY CALM OVERNIGHT BUT WILL
GRADUALLY SHIFT TO A SOUTHWESTERLY DIRECTION AS THE HIGH PUSHES OUT
TO SEA. -ELLIS
TUESDAY:
LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE ACROSS THE AREA ALONG
WITH A WEAK UPPER LEVEL DISTURBANCE MOVING ACROSS THE AREA IN THE SW
FLOW. NOT EXPECTING ANY PRECIP AS WE WILL HAVE A LOT OF DRY MID
LEVEL AIR AND NOT ENOUGH ISENTROPIC LIFT AND MOISTURE IN THE LOW
LEVELS. LOW LEVEL MOISTURE RETURN SHOULD ALLOW FOR AT LEAST PARTLY
SUNNY TO EVEN MOSTLY CLOUDY SKIES ACROSS A GOOD PORTION OF THE AREA
TUESDAY... WITH THE EARLIEST AND MOST CLOUDS ACROSS THE WEST AND
SOUTH/SOUTHWEST... WITH THE LEAST IN THE NORTHEAST. AFTERNOON LOW
LEVEL THICKNESS VALUES ARE PROGGED TO BE AROUND 15 METERS HIGHER
THAN TODAY. HOWEVER... THANKS TO THE INCREASE IN CLOUD COVER HIGH
TEMPS OVER MOST OF THE AREA WILL NOT BE ABLE TO REACH THEIR FULL SUN
HIGHS.... ESPECIALLY IN THE WEST... WHICH IS SHOWN IN THE
STATISTICAL GUIDANCE WELL. THUS... WILL GO WITH HIGH TEMPS RANGING
FROM THE LOWER 50S WEST TO UPPER 50S/NEAR 60 EAST/SOUTHEAST. -BSD
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 300 PM MONDAY...
ELONGATED AREA OF HIGH PRESSURE AT THE SURFACE EXTENDING WNW TO ESE
OVER NC THROUGH THE PERIOD. RETURN FLOW AROUND THE HIGH WILL ADVECT
MOISTURE INTO THE CAROLINAS FROM THE ATLANTIC. WILL LIKELY SEE AN
INCREASE IN LOW CLOUDS TUESDAY NIGHT. GOOD ISENTROPIC UPGLIDE SHOULD
YIELD SOME LOW STRATUS ACROSS CENTRAL NC WEDNESDAY MORNING. HIGH
CLOUDS WILL SPREAD EASTWARD ACROSS THE AREA AHEAD OF A LOW PRESSURE
SYSTEM TO THE WEST. THIS PART OF THE FORECAST SHOULD REMAIN MOSTLY
DRY...WITH THE CHANCE OF A FEW SPRINKLES ACROSS THE SOUTH THURSDAY
MORNING. EXPECT HIGHS ON WEDNESDAY IN THE LOW TO MID 60S...WITH LOWS
INCREASING FROM MID 30S TO NEAR 40 TUESDAY NIGHT TO THE LOW TO UPPER
40S WEDNESDAY NIGHT.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 310 PM MONDAY...
THURSDAY THROUGH SATURDAY NIGHT:
LOW PRESSURE OVER TX WEDNESDAY NIGHT WILL GET ABSORBED IN THE
LONGWAVE TROUGH AS IT MOVE NORTHEAST ON THURSDAY. GOOD INFLUX OF
GULF MOISTURE AHEAD OF THE SYSTEM WILL HELP GENERATE PRECIP AHEAD OF
IT. THE MAJORITY OF THE PRECIP WILL RIDE NE OVER THE H85 HIGH
MEANDERING OFF THE SC COAST. BEST CHANCES FOR PRECIP OVER CENTRAL NC
WILL BE A RESULT OF ISENTROPIC UPGLIDE FROM THE MOIST RETURN FLOW
AROUND THE HIGH. A HYBRID COLD AIR DAMMING EVENT IS LIKELY LATE THIS
WEEK AND POSSIBLY INTO THE WEEKEND AS THE SURFACE HIGH PRESSURE
BUILDS INTO THE NC PIEDMONT FROM THE NE...BEGINNING LATE THURSDAY.
THE FORECASTED PRECIP IN THE NORTHWEST THURSDAY AND FRIDAY WILL HELP
TO MOISTEN AND COOL THE LOW LEVELS AND LOCK IN THE COLD AIR. WITH
THE DAMMING IN PLACE AND THE WARM MOIST AIR EXPECTED TO OVERRUN THE
COOL STABLE LAYER IN THE NW...WILL LIKELY SEE AN EXTENDED PERIOD OF
OVERCAST SKIES...LIGHT RAIN IN THE FAVORED DAMMING REGION...AND A
STRONG GRADIENT IN TEMPERATURE FROM THE NW TO SE PORTION OF THE
AREA. THERE IS SIGNIFICANT UNCERTAINTY WITH REGARD TO WHEN THE CAD
WILL ERODE...WHICH WILL GREATLY IMPACT TEMPERATURES DURING THAT
TIME. AT THIS TIME...HAVE KEPT THE WEDGE OF COLD AIR IN THROUGH
SATURDAY. HIGH TEMPS ON THURSDAY SHOULD BE IN THE MID 50S TO LOW 60S
AND OVERNIGHT LOWS NEAR 40 IN THE NE TO UPPER 40S SW. WITH THE COLD
AIR IN PLACE ACROSS THE NW...CURRENTLY HAVE HIGHS ON FRIDAY IN THE
MID 50S NW TO MID 60S SE INCREASING ON SATURDAY TO MID 60S NW TO LOW
70S SE. OVERNIGHT LOWS FRIDAY AND SATURDAY NIGHTS IN THE MID 40S NW
TO LOW 50S SE.
SUNDAY THROUGH MONDAY:
ASSUMING THE WEDGE ERODES ON SATURDAY...WILL SEE IMPROVING WEATHER
CONDITIONS ON SUNDAY. MODELS CURRENTLY SHOW THE NEXT WEATHER SYSTEM
MOVING INTO THE WEST MONDAY MORNING...WITH THE BEST CHANCES FOR
PRECIP ACROSS THE AREA LATE MONDAY MORNING AND INTO THE AFTERNOON.
HIGH TEMPS ON SUNDAY ARE FORECAST IN THE UPPER 60S TO LOW 70S. WITH
INCREASING CLOUDINESS AND CHANCES FOR SHOWERS...HIGHS ON MONDAY MAY
BE A FEW DEGREES COOLER...LOW 60S TO NEAR 70. OVERNIGHT LOWS UPPER
40S TO LOW 50S.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 1240 AM TUESDAY...
WITH HIGH PRESSURE NOW SETTLING EAST ALONG THE COAST...EASTERLY LOW
LEVEL WINDS ARE BEGINNING TO USHER MOISTURE INLAND ACROSS THE
CAROLINAS. STRATUS HAS DEVELOPED OVER THE SC COASTAL AREAS AND IS
STARTING TO SPREAD INLAND TO THE WEST-NORTHWEST. SATELLITE TRENDS
WOULD SUGGEST THIS MOISTURE COULD REACH KFAY BY 12Z...AND HRRR MODEL
CEILING FORECASTS SUPPORT THIS. THUS...THERE IS INCREASING
CONFIDENCE THAT MVFR...OR NEAR MVFR CEILINGS WILL MOVE DEVELOP AT
KFAY BY AROUND 12 AND KRDU/KRWI BY 15Z. WILL ALSO CONTINUE A LOW
CONFIDENCE CHANCE OF LOCALIZED FOG/STRATUS AT KRWI THROUGH 12Z.
DAYTIME HEATING MAY CAUSE THE CLOUD DECK TO SCATTER A BIT BY THIS
AFTERNOON...BUT THERE SHOULD STILL BE ENOUGH MOISTURE BELOW A STRONG
SUBSIDENCE INVERSION TO KEEP CONDITIONS ON AT LEAST THE THE EDGE OF
MVFR. FURTHER WEST AT KGSO/KINT...MVFR CONDITIONS ARE NOT RULED
OUT...BUT CONFIDENCE IS MUCH LOWER.
TONIGHT...AS WINDS CONTINUE TO SHIFT AROUND TO
SOUTH-SOUTHWESTERLY...THERE IS A BETTER CHANCE OF MVFR AND/OR IFR
CEILINGS..ESPECIALLY AT WESTERN TERMINALS (KGSO/KINT)
OUTLOOK...
AN EXTENDED PERIOD OF CLOUDINESS WITH SUB-VFR CONDITIONS IN LIGHT
RAIN WILL THEN BE POSSIBLE THURSDAY AND FRIDAY AS A WARM FRONT
APPROACHES FROM THE SOUTH-SOUTHWEST.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BSD
NEAR TERM...ELLIS/BSD
SHORT TERM...KC
LONG TERM...KC
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1206 AM EST TUE JAN 8 2013
.SYNOPSIS...
A DEVELOPING OFFSHORE COASTAL TROUGH WILL PARALLEL THE CAROLINA
COAST THROUGH TUESDAY...THEN DISSIPATE ON WEDNESDAY. A STORM
SYSTEM...MOVING NORTHEAST OUT OF THE PLAIN STATES...WILL BRING A
WARM FRONT ACROSS THE AREA LATE WEEK. HIGH PRESSURE WILL BRING WARM
TEMPERATURES AND DRY WEATHER FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
AS OF 1035 PM MONDAY...MID TO HIGH LEVEL CLOUDS CONTINUE TO EXPAND
NORTHWARD ACROSS THE FA THIS EVENING AND OVERNIGHT...WITH A LOW
DECK POSSIBLE ALONG THE IMMEDIATE COAST AS LATEST HRRR MODEL
INDICATES AN INVERTED SFC TROF TO DEVELOP JUST OFFSHORE LATE
TONIGHT. OVERNIGHT TEMPS/DEWPOINTS CONTINUE TO BE MASSAGED...MOSTLY
TOWARD THE UPWARD SIDE DUE TO INCREASING OPAQUE SKY COVER. WINDS
ACROSS THE INLAND COUNTIES WILL HAVE THE POTENTIAL TO DECOUPLE AS
THE CENTER OF THE SFC HIGH EXTENDS ACROSS THIS AREA. COULD OBSERVE
NEAR FREEZING READINGS IF RAD COOLING CONDITIONS PERSIST
THROUGH THE OVERNIGHT.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...AS WEDGE OF HIGH PRESSURE HANGS ON AT THE
SURFACE IN A WEDGE-LIKE SCENARIO THE MAIN FORECAST ISSUE ON TUES
SEEMS TO BE THE EXTENT OF CLOUD COVER THAT MANAGES TO DEVELOP. E TO
NE WINDS BENEATH WARM ADVECTION/SW FLOW AT 850 MB LEADS TO A NEARLY
ISOTHERMAL LAYER FROM VERY ROUGHLY 950-850MB WITH FAIRLY HIGH RH.
ABOVE THIS LAYER IS VERY DRY AIR ASSOCIATED WITH SUBSIDENCE
INVERSION. ACTUAL MIXING IS FORECAST TO BE QUITE SHALLOW SO THIS DRY
AIR MAY NOT COME TO BEAR TOO MUCH WITH RESPECT TO CLOUD COVER
OBSERVED AT THE SURFACE...I JUST WONDER IF GUIDANCE IS BRINGING IN
TOO MUCH MOISTURE OFF OF THE ATLANTIC. THE ACTUAL FRONTAL BAND
SHOULD NOT MAKE IT THIS FAR NORTH AND WEST AND GUIDANCE IS IN
FAIRLY GOOD AGREEMENT THAT LOW LEVEL ISENTROPIC UPGLIDE IS VERY
SLOW OR EVEN NOT FORECAST TO DEVELOP UNTIL NIGHTTIME. SHOW A GRADUAL
UPWARD TREND IN SKY COVER BUT WILL CAP VALUES NEAR UPPER RANGES OF
PARTLY CLOUDY SAVE FOR SOUTHERN ZONES WHICH WILL REGISTER MOSTLY
CLOUDY IN TEXT PRODUCTS IN ALL LIKELIHOOD. SMALL POPS HINTED AT IN
GUIDANCE SEEMS IMPLAUSIBLE DUE TO AFOREMENTIONED DRY AIR. DRIZZLE
SEEMS LIKE WORST CASE. BY WEDNESDAY THE HIGH SHOWS VERY LITTLE
MOVEMENT BUT WEAKENS SUFFICIENTLY TO NO LONGER IMPLY COOL AIR
WEDGING. MIXING IS FORECAST TO REMAIN QUITE SHALLOW AND SO SOME OF
THE LOW LEVEL WARM AIR ADVECTION MAY NOT BE REALIZED AT THE SURFACE
(ESPECIALLY IF THE CLOUD COVER CONTINUES TO INCREASE). BASED UPON
THIS AND SIMILAR CONCERN NOTED BY SOME NEIGHBORS HAVE TRIMMED WED
HIGHS A FEW DEGREES BELOW GUIDANCE. MOISTURE PROFILE A LITTLE DEEPER
IN FORECAST SOUNDINGS BUT RAIN CHANCES WILL STAY CAPPED AT SLIGHT
CHANCE IN THE ABSENCE OF ANY REAL FORCING MECHANISM.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 3 PM MONDAY...MAIN DETAILS OF THE SYNOPTIC PATTERN FOR THE
EXTENDED REMAIN IN PLACE THIS AFTERNOON AS A STRONG CLOSED LOW
WILL MOVE QUICKLY THROUGH THE MIDWEST AND SHEAR OUT. THE FLOW
BETWEEN THIS FEATURE AND AN ANOMALOUS RIDGE TO THE SOUTHEAST WILL
CREATE A VERY WARM AND PERSISTENT FLOW.
THE LOW...BEFORE SHEARING OUT AND FILLING IS 3-4 STAND DEVIATIONS
BELOW NORMAL AND THE RIDGE IS 1-2 ABOVE. 850MB TEMPERATURES OF 13-15
DEGREES C WILL ADVECT INTO THE AREA FOR THE WEEKEND. MEX GUIDANCE IS
ADVERTISING WIDESPREAD 70S FOR THE THIRD DAY IN A ROW AND THE
FORECAST HAS BEEN ADJUSTED UPWARD AS EVEN THE COOLER HPC NUMBERS ARE
MOSTLY IN THE 70S FOR THE WEEKEND. THE ONLY RECORD THAT APPEARS IN
JEOPARDY AT THIS TIME IS FLORENCE FOR SATURDAY WHICH IS 73 DEGREES.
THE KICKER SYSTEM...THE ONE THAT FORCES THE INITIAL DEEP LOW TO MOVE
OUT BEGINS TO IMPACT THE REGION MONDAY WITH INCREASED CLOUDINESS AND
SLIGHT CHANCE POPS HENCE...SLIGHTLY COOLER TEMPERATURES.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 06Z...CLOUDS WILL LOWER WITH TIME AND WILL FORECAST CEILINGS
LOWERING FROM VFR TO MVFR AT ALL THE TERMINALS THROUGH DAYBREAK AS A
COASTAL TROUGH CONTINUES TO DEVELOP. MOIST RETURN FLOW AROUND HIGH
PRESSURE CENTERED OFFSHORE WILL KEEP BKN TO AT TIMES OVC CONDITIONS
AFTER DAYBREAK AS WELL. CEILINGS ARE EXPECTED TO LIFT TO VFR 12-14Z.
EXTENDED OUTLOOK...POSSIBLE MVFR CIGS/VSBYS WEDNESDAY ASSOCIATED
WITH A COASTAL TROUGH. SLIGHT CHANCE OF SHOWERS WEDNESDAY AND
THURSDAY. VFR DEVELOPING FRIDAY AND PERSISTING THROUGH SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF MIDNIGHT TUESDAY...HEADLINED SMALL CRAFT SHOULD EXERCISE
CAUTION THROUGH 11 AM TUE. A DEVELOPING COASTAL TROUGH WAS
TIGHTENING THE PRESSURE GRADIENT ACROSS THE WATERS...RESULTING IN
WINDS OF NEAR 20 KT WITH GUSTS NEAR 25 KT. THESE HIGHER WINDS WERE
PRODUCING SEAS OF 4 TO 5 FT ACROSS THE MAJORITY OF THE OUTER WATERS.
THESE CONDITIONS ARE EXPECTED TO PERSIST THROUGH MUCH OF THE
MORNING. THE WIND DIRECTION WILL REMAIN NE OVERNIGHT AS THE TROUGH
REMAINS TO OUR E.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...WEDGE-LIKE HIGH PRESSURE IN PLACE ON TUESDAY TO
BRING A LIGHT NE FLOW...GENERALLY IN THE 10 TO 15 KT RANGE. SEAS 2
TO 3 FT IN A PREDOMINANT 5 SECOND WIND CHOP. ON WEDNESDAY THE HIGH
BOTH WEAKENS AND MOVES EVER SO SLIGHTLY TO THE N. WINDS MAY VEER TO
EASTERLY WHILE THEY DROP TO ABOUT 10 KT. THIS WILL CUT OUT THE 3 FT
SEAS AND MOST PLACES WILL BE CAPPED AT 2 FT. DOMINANT PERIOD LIKELY
STAYS ABOUT 5 OR 6 SECONDS BUT A VERY SMALL 10 SECOND EASTERLY SWELL
IS ALSO FORECAST.
LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 3 PM MONDAY...MAIN EVENT FOR THE MARINE COMMUNITY WILL BE THE
WIND SHIFT OCCURRING FRIDAY MORNING AS A WARM FRONT MOVES ACROSS.
CONFIDENCE IS NOT ALL THAT GREAT AT LEAST IN REGARDS TO TIMING AS
MEDIUM RANGE GUIDANCE HAS BEEN JUMPING AROUND SOMEWHAT. EXPECT A
GRADUAL VEERING FROM NORTHEAST THURSDAY AFTERNOON TO SOUTH BY FRIDAY
AT 1200 UTC. SPEEDS REMAIN MARGINAL WITH 10-15 KNOTS. EXPECT MORE
WESTERLY WINDS SATURDAY COURTESY OF A GLANCING SHOT FROM A BACKDOOR
FRONT. SIGNIFICANT SEAS LOOK FAIRLY CONSISTENT WITH THE WAVEWATCH
STILL A BIT ON THE HIGH SIDE. THERE COULD STILL BE A SCEC HEADLINE
ESPECIALLY EARLY BUT THE WIND SHIFT SHOULD PRECLUDE A SMALL CRAFT
ADVISORY WITH 3-5 FEET EXPECTED.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...DCH/RJD
SHORT TERM...MBB
LONG TERM...SHK
AVIATION...RJD/DL
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1036 AM CST TUE JAN 8 2013
.DISCUSSION...
MAIN CHANGE FOR THIS MORNING WAS TO ADD SOME FZDL MENTION FOR THE
REST OF THE MORNING INTO THE EARLY AFTERNOON. PRECIP HAS ENTERED
THE CWA MAINLY FROM THE RED RIVER VALLEY WESTWARD. NOT MUCH SNOW
ACCUMULATION SO FAR...BUT WE HAVE HAD A FEW REPORTS OF SLICK ROADS
DUE TO FZDL AROUND FARGO TOWARDS CASSELTON. MODEL SOUNDINGS HAVE A
SHALLOW MOIST LAYER WITH A DRY WARM LAYER ABOVE THROUGH MID
AFTERNOON. TEMPS HAVE BEEN QUICK TO WARM UP THIS MORNING OVER THE
WESTERN CWA EVEN WITH WINDS STILL FROM THE SOUTH. RAP SEEMS TO
HAVE A GOOD HANDLE ON THE WARMING AND WENT CLOSE TO THAT MODEL
SOLUTION FOR THE REST OF THE DAY. CONTINUE TO THINK THAT TEMPS
WILL WARM TO CLOSE TO THE FREEZING MARK BY THIS AFTERNOON.
MOST OF THE PRECIP SHOULD BE OVER THE NORTHEASTERN CWA BY LATE THIS
POINT...AND THAT AREA SHOULD BE A BIT COLDER SO KEPT TYPE AS SNOW
FOR NOW BUT WILL HAVE TO KEEP AN EYE ON IT.
WINDS WILL ALSO BE AN ISSUE FROM LATE THIS AFTERNOON INTO THE
EVENING. SOME OF THE MODEL GUIDANCE HAS THE NORTHWESTERN TO NORTH
CENTRAL CWA FLIRTING WITH ADVISORY CRITERIA. ON THE OTHER
HAND...MIXING WILL BE AT A MINIMUM AND THERE IS NO COLD AIR
ADVECTION TO HELP BRING HIGHER LEVEL WINDS TO THE SFC. WILL HOLD
OFF ON ANY HEADLINES FOR NOW AND REEVALUATE FOR THE AFTERNOON PACKAGE.
&&
.AVIATION...
WILL SEE INCREASING CLOUD COVER WITH PERIODS OF LIGHT SNOW
FROM WEST TO EAST TODAY AS A LOW PRESSURE SYSTEM MOVES ACROSS THE
REGION. VFR CEILINGS SHOULD DOMINATE...BUT MAY BRIEFLY DIP INTO
THE MVFR RANGE WITH LIGHT SNOW AND REDUCTIONS IN VISIBILITY DOWN
TO 1-5 SM. SOUTH-SOUTHWEST WIND WILL SHIFT TO THE WEST LATER THIS
AFTERNOON AND EVENING BEHIND COLD FRONT WITH FREQUENT GUSTS AT OR
ABOVE 30 KTS.
&&
.PREV DISCUSSION... /ISSUED 353 AM CST TUE JAN 8 2013/
SHORT TERM...TODAY THROUGH THURSDAY NIGHT
FORECAST CHALLENGES INCLUDE SNOW CHANCES/AMOUNTS AND WIND TODAY...
FOLLOWED BY PRECIPITATION CHANCES AGAIN ON THURSDAY. GFS/NAM/ECMWF/
GEM ARE IN GOOD OVERALL AGREEMENT AND WILL USE A BLENDED SOLUTION.
FOR TODAY...EASTERN PACIFIC SHORT-WAVE WILL MOVE ACROSS SOUTHERN
CANADA AND THE NORTHERN PLAINS. SURFACE LOW WILL REMAIN NORTH OF
THE BORDER...BUT THE COLD FRONT/TROUGH AXIS WILL MOVE ACROSS THE
ND/MN BORDER AND INTO NORTHWEST MN BY 00 UTC TONIGHT. MID-LEVEL
FRONTOGENESIS AND MOISTURE NOT ALL TOO IMPRESSIVE...BUT 300 HPA
JET STREAK...COMBINED WITH MID-LEVEL CONVERGENCE WILL RESULT IN
LIGHT SNOW MOVING ACROSS THE FORECAST AREA TODAY. WILL BE A HIGH
POP/LOW QPF SCENARIO WITH THE BEST CHANCES FOR ACCUMULATING
SNOWFALL ALONG AND NORTH OF THE HIGHWAY 2 CORRIDOR. MOST AREAS
WILL SEE AN INCH OR LESS THROUGH WEDNESDAY MORNING...BUT UP TO 2
INCHES ARE POSSIBLE ACROSS THE LAKE OF THE WOODS AREA. WITH LESS
FAVORABLE SOUTHERLY SURFACE WIND AHEAD OF THE FRONT AND MODEST
COLD AIR ADVECTION IN ITS WAKE...EXPECT HIGH TEMPERATURES TODAY
AT OR SLIGHTLY COOLER THAN YESTERDAY.
MODELS STILL SHOW 40 TO 50 KTS AT 925 HPA ALONG AND WEST OF THE
VALLEY BY 06 UTC TONIGHT. PREFER NAM/S DEPICTION OF MIXED BOUNDARY
LAYER...WHICH DEEPENS IT TO AROUND 950 HPA OVERNIGHT. THIS PROVIDES
AROUND 30 KTS TO MIX TO THE SURFACE IN AREA OF STRONGEST PRESSURE
GRADIENT. AS A RESULT...LEANED TOWARDS HIGHEST LOCAL WRF GUIDANCE
FOR WIND SPEED...BUT THIS STILL KEEPS IT JUST BELOW WIND ADVISORY
CRITERIA (SUSTAINED 30 MPH). COULD SEE A FEW HOURS GREATER THAN 30
MPH WEST OF THE VALLEY...BUT CONFIDENCE NOT HIGH ENOUGH TO ISSUE
ANY HEADLINES AT THIS TIME. WILL ALLOW DAY SHIFT TO RE-EVALUATE
SINCE THE STRONGEST WIND WOULD BE DELAYED UNTIL AFTER 21 UTC THIS
AFTERNOON. ALTHOUGH MAJORITY OF FALLING SNOW WILL END AFTER 00
UTC...DID INCLUDE AREAS OF BLOWING SNOW THIS EVENING INTO THE
EARLY MORNING HOURS WEDNESDAY ALONG AND WEST OF THE VALLEY.
REMAINING SNOW WILL MOVE OUT OF THE REGION BY WEDNESDAY MORNING
WITH A SURFACE RIDGE MOVING ACROSS THE FORECAST AREA. EXPECT
PLENTY OF SUNSHINE WEDNESDAY...BUT TEMPERATURES WILL BE A BIT
COOLER WITH AFTERNOON HIGHS IN THE MID 20S ALONG THE CANADIAN
BORDER TO NEAR 30 DEGREES ACROSS THE SOUTHERN VALLEY. WINDS WILL
BE LIGHT FROM THE WEST-SOUTHWEST.
MOST OF THURSDAY WILL BE DRY...BUT MODELS DO HINT THAT THE
NORTHWEST FLANK OF A PRECIPITATION SHIELD ASSOCIATED WITH A GREAT
LAKES LOW PRESSURE SYSTEM WILL CLIP PORTIONS OF THE SOUTHEAST
FORECAST AREA THURSDAY EVENING. WILL KEEP 40 TO 60 POPS FOR THIS
PERIOD ALONG AND EAST OF THE VALLEY. BIGGER STORY FOR THURSDAY
WILL BE WARM TEMPERATURES WITH 850 HPA VALUES CLIMBING TO +6 C.
THIS SHOULD TRANSLATE TO SURFACE TEMPERATURES IN THE MID 30S. IF
PRECIPITATION DOES TRACK FARTHER NORTH...MAY NEED TO WATCH
P-TYPE GIVEN WARM MID-LEVELS.
LONG TERM...FRIDAY THROUGH MONDAY NIGHT
MODELS ARE COMING INTO BETTER AGREEMENT WITH AN ACTIVE WEATHER
PATTERN FOR FRI-SAT...WITH SW FLOW ALOFT. THERE ARE DIFFERENCES IN
THE DETAILS AND EXACT TIMING...BUT ALL INDICATIONS POINTING TO
ACCUMULATING SNOW POSSIBLE FRIDAY INTO SATURDAY...MUCH COLDER TEMPS
AND NORTHERLY WINDS INCREASING. FOR NOW HAVE KEPT WITH CHANCE POPS
FOR LIGHT SNOW FRI INTO SAT...BUT WE MAY NEED TO INCREASE THESE POPS
WITH SEVERAL SHORTWAVES MOVING THROUGH. THE BEST CHANCE FOR
ACCUMULATING SNOW AND POTENTIAL WINTER WEATHER HEADLINES WOULD BE
FRI AFTERNOON INTO SATURDAY...ALTHOUGH TIMING OF THIS MAY CHANGE
WITH PLENTY OF TIME TO RESOLVE MODEL DIFFERENCES.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
JR
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1103 PM CST MON JAN 7 2013
.DISCUSSION...
SEEING SOME PATCHY FOG ACROSS TYPICAL COOL SPOTS IN NORTHWEST IOWA
THIS EVENING. MODELS STILL SHOW AN INCREASE IN MID-HIGH CLOUDS OVER
NORTHERN HALF OF THE CWA THROUGH THE NIGHT...WITH SOME THIN CIRRUS
ACROSS THE SOUTH. NOT EXPECTING FOG TO GET TOO OUT OF HAND...BUT DID
ADD MENTION OF PATCHY DENSE FOG BASED ON VISIBILITY REPORTS FROM
SHELDON/SPENCER AREAS. SHELDON AWOS ALSO REPORTING DRIZZLE...BUT
CALL TO SHERIFF IN THAT AREA REVEALED ONLY SPOTTY FOG AND NO ICING.
HAVE MADE MINOR ADJUSTMENTS TO SOME HOURLY TEMPERATURES THROUGH THE
EVENING...BUT OVERALL LOWS SEEM REASONABLE AND SEE NO REASON FOR ANY
MAJOR CHANGES THERE AT THIS TIME. UPDATED GRIDS HAVE BEEN SENT.
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
MAIN AVIATION CONCERN THIS PERIOD IS RESIDUAL LOW LEVEL MOISTURE
FROM MELTING SNOW...MAINLY IN SOUTHEAST PARTS OF THE AREA WHERE WEAK
WINDS AND MINIMAL SKY COVER ARE EXPECTED THROUGH THE EARLY MORNING.
HAVE ALREADY SEEN SPOTTY IFR-LIFR VISIBILITY/CEILINGS IN PARTS OF
NORTHWEST IOWA AND WITH FAVORABLE DRAINAGE WIND OUT OF THE MISSOURI
VALLEY INTO KSUX AIRPORT COULD BRING SIMILAR CONDITIONS TO THAT SITE
THROUGH SUNRISE. LIGHT SOUTHERLY WINDS WILL INCREASE A BIT AHEAD OF
BOUNDARY SET TO PUSH THROUGH THE REGION TUESDAY AFTERNOON/EVENING.
WINDS WILL INCREASE FURTHER BEHIND BOUNDARY...AND MODELS APPEAR TO
HANG ON TO TOO COOL SURFACE LAYER TEMPS AND DO NOT ALLOW FOR THE
BETTER MIXING THAT PROGGED SURFACE READINGS WOULD ALLOW...SO PUT IN
SOME WIND GUSTS DURING THE AFTERNOON EXCEEDING 25 KNOTS AROUND
KHON...AND CLOSE TO THRESHOLD FOR KFSD/KSUX A BIT LATER INTO THE
AFTERNOON. STRONG WINDS REMAIN JUST OFF THE SURFACE THROUGH THE
EVENING...AND WITH VERY SHALLOW INVERSION WILL HANG ONTO THE GUSTY
WINDS INTO EVENING.
&&
.PREV DISCUSSION.../ISSUED AT 343 PM CST/
MULTIPLE PLAYERS IN TODAY/S FORECAST FOR TONIGHT INTO TOMORROW.
CURRENTLY...MOSTLY CLEAR SKIES ACROSS THE AREA WITH A FEW HIGH
CLOUDS ACROSS CENTRAL SOUTH DAKOTA. THE SUNSHINE HAS PROMOTED SNOW
MELT...BUT WITH WEAK WINDS AND STRONG INVERSION...MOISTURE REMAINS
IN THE NEAR SURFACE LAYER. COULD SEE FOG DEVELOP OVERNIGHT
TONIGHT...BUT TRICKY TO PIN POINT WHERE EXACTLY. HRRR CONTINUES TO
SUGGEST THAT PATCHY FOG WILL BE POSSIBLY ACROSS THE NORTH...WHILE
NAM FOCUSES ON THE SOUTH AND EAST. HAVE SIDED CLOSER TO NAM...BUT
WITH WEAK WINDS...COULD GET RADIATIONAL FOG NEARLY ANYWHERE CLEAR
SKIES REMAIN FOR A FEW HOURS. AS MENTIONED IN THE MORNING
DISCUSSION...AMPLIFYING WAVE MOVING ACROSS THE AREA LATE TONIGHT
WITH UPPER LEVEL DIV Q INCREASING AFTER 06Z MAINLY ACROSS THE
NORTHERN HALF OF THE FORECAST AREA. WITH FAIRLY DRY AIR THROUGH THE
MID LEVELS OF THE ATMOSPHERE...AM NOT EXPECTING ANY PRECIPITATION
AND DROPPED MENTION OF SPRINKLES/FLURRIES FROM THE FORECAST. IF FOG
DEVELOPS IN THE SOUTHEAST...WILL NEED TO KEEP AN EYE ON DRIZZLE
POTENTIAL WITH WEAK LIFT IN THE LOW LEVELS OF THE ATMOSPHERE.
COLD FRONT IS POISED TO MOVE THROUGH THE AREA ON TUESDAY. SOUTHERLY
WINDS WILL BECOME WEST AND SOMEWHAT GUSTY BEHIND THE FRONT WITH
20-30 KNOTS OF FLOW AT 925 HPA. NOT MUCH IN THE WAY OF COLD AIR
ADVECTION BEHIND THE FRONT...AND WITH ONLY MEAGER PRESSURE RISES AND
STRONG INVERSION REMAINING ALOFT...WILL STRUGGLE TO GET A LOT OF THE
MOMENTUM DOWN THE SURFACE. STRONGEST WINDS WILL LIKELY BE ACROSS
THE NORTHERN EDGE OF THE FORECAST AREA WITH STRONGEST GRADIENT WINDS
THERE...BUT STILL LOOK TO REMAIN BELOW ADVISORY CRITERIA.
UPPER LEVEL TROUGH IS EXPECTED TO DIG ACROSS THE DESERT SOUTHWEST
MID WEEK...WHICH PUSHES THE RIDGE AXIS OVER THE FORECAST AREA ON
WEDNESDAY. EXPECT ANOTHER RELATIVELY MILD DAY WITH MOSTLY SUNNY
SKIES AND ABOVE NORMAL TEMPERATURES. EXPECT HIGHS TO REACH JUST
ABOVE FREEZING IN SOUTHWEST MINNESOTA AND ADJACENT AREAS...NUDGING
INTO THE UPPER 30S IN NORTHWEST IOWA. THE WARMEST READINGS WILL BE
FOUND IN SOUTH CENTRAL SOUTH DAKOTA WITH THE MID OR UPPER 40S IN
AREAS WHERE MUCH OF THE SNOWPACK HAS MELTED.
FOR THURSDAY...A CUT OFF LOW IS EXPECTED TO FORM IN THE SOUTHWEST
PLAINS AND TRACK NORTHEAST INTO THE NORTHERN GREAT LAKES EARLY
SATURDAY. SOME MODEL DIFFERENCES STILL EXIST...WITH THE ECMWF AND
GEM STILL FOLLOWING A SLOWER AND SLIGHTLY MORE SOUTHERLY TRACK. ALL
MODELS DO CLIP OUR SOUTHEASTERN COUNTIES AS THE SURFACE LOW TRACKS
INTO IOWA THURSDAY EVENING. TEMPERATURES WILL BE PARTICULARLY TRICKY
WITH READINGS EXPECTED TO RISE UP ABOVE FREEZING BY THE AFTERNOON.
WITH VERY WARM LOW LEVELS...EXPECT PRECIPITATION TO BE ENTIRELY
LIQUID FOR THIS SYSTEM...BUT WITH SURFACE READINGS POTENTIALLY BELOW
FREEZING IN THE MORNING AND AGAIN THURSDAY NIGHT...FREEZING RAIN
WILL ALSO BE POSSIBLE. BUT GIVEN THAT THESE TEMPERATURES WILL ONLY
BE A DEGREE OR TWO BELOW FREEZING...ICE ACCUMULATION DOES NOT LOOK
TO BE SIGNIFICANT. BUT WILL STILL CONTINUE TO MONITOR FOR ANY
CHANGES IN THIS OUTLOOK.
TEMPERATURES ON FRIDAY WILL LIKELY BE SOMEWHAT STEADY OR BEGIN TO
FALL IN THE AFTERNOON AS COOLER TEMPERATURES BEGIN TO FILTER INTO
THE AREA BEHIND THIS SYSTEM. THE BROAD POSITIVELY TILTED TROUGH
DIGGING ACROSS THE SOUTHWEST PUSHES INTO THE WESTERN PLAINS FRIDAY
EVENING...BRINGING THE NEXT POTENTIAL FOR WET WEATHER TO REGION
FRIDAY NIGHT AND SATURDAY. AGAIN...THE ECMWF IS A BIT SLOWER AND
SHOWS MORE OF A CLOSED UPPER LEVEL FEATURE. A SLIGHT CHANCE FOR SOME
LIGHT SNOW OR FLURRIES WILL BE POSSIBLE AHEAD OF THE MAIN WAVE ON
FRIDAY. THE DETAILS ARE STILL QUITE UNCERTAIN AT THIS POINT...BUT
THE GFS APPEARS TO TAKE THE BEST DYNAMICS WEST AND NORTH OF THE
FORECAST AREA...WHILE THE ECMWF HAS A BIT MORE ORGANIZATION WITH A
DECENT BAND OF MID LEVEL FRONTOGENESIS MOVING THROUGH THE FORECAST
AREA. WILL KEEP MENTION OF POPS AS A HIGH CHANCE FOR SOME LIGHT
SNOWFALL FRIDAY NIGHT AND SATURDAY. PRELIMINARY AMOUNTS LOOK LIKE A
FEW INCHES WOULD BE POSSIBLE ACROSS THE CWA.
THE LOW EXITS THE AREA SATURDAY NIGHT WITH A STRONGER SHOT OF COLD
AIR ADVECTION ARRIVING IN ITS WAKE. TEMPERATURES WILL BE MUCH COOLER
FOR THE START OF NEXT WEEK WITH HIGHS MAINLY IN THE TEENS AND LOWS
AROUND ZERO.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1158 AM CST TUE JAN 8 2013
.AVIATION...
/18Z TAFS/
CONCERNS...ONGOING LOW CIGS/VSBY AND THUNDER POTENTIAL.
INITIAL MASS OF LIGHT RAIN ASSOCIATED WITH LARGE UPPER LEVEL STORM
SYSTEM OVER NORTHERN MEXICO HAS MOVED INTO N TEXAS THIS
MORNING...BRINGING WIDESPREAD MVFR/AREAS OF IFR TO ALL SITES. AS
MOISTURE INFLOW AND LIFT INCREASE AHEAD OF THIS SYSTEM LATER
TODAY/TONIGHT...EXPECT WIDESPREAD RAIN AND IFR CONDITIONS TO
DEVELOP AND PERSIST THROUGH AT LEAST MIDDAY WED. LIMITED
INSTABILITY EXISTS ALOFT...INCREASING TO THE S AND E OF THE
METROPLEX TAF SITES. GIVEN THIS...EXPECT OCCASIONAL THUNDER AT ALL
TAF SITES THROUGH TONIGHT. SURFACE WINDS SHOULD CONTINUE TO BACK
TO A NE-N DIRECTION TONIGHT AND INCREASE AS SURFACE LOW DEVELOPS
OVER S TEXAS.
66
&&
.UPDATE...
CURRENT FORECAST IS IN GOOD SHAPE AND ONLY MADE SOME MINOR CHANGES
TO THE SKY/POP GRIDS TO ACCOUNT FOR CURRENT OBSERVATIONS. CURRENT
ANALYSIS OF AVAILABLE 12Z GUIDANCE CONTINUES TO SHOW THAT
WIDESPREAD HEAVY RAINFALL IS LIKELY THROUGH WEDNESDAY. INITIAL
ACTIVITY HAS BEEN SOMEWHAT SCATTERED AS BROAD ISENTROPIC ASCENT
OVERSPREADS THE AREA. LATEST RAP SOUNDINGS FROM ACROSS NORTH TEXAS
INDICATE ABOUT 100-200J/KG OF ELEVATED INSTABILITY WHICH HAS BEEN
SUFFICIENT FOR ISOLATED THUNDERSTORMS CAPABLE OF PRODUCING SMALL
HAIL. AS DEEPER LARGE SCALE FORCING OVERSPREADS CENTRAL AND NORTH
TEXAS TONIGHT...A WELL DEFINED WARM CONVEYOR BELT WILL BECOME
ESTABLISHED AND AREAL COVERAGE OF PRECIPITATION IS EXPECTED TO
INCREASE. HEAVIEST RAINS STILL EXPECTED OVERNIGHT TONIGHT INTO
EARLY WEDNESDAY...SO NO CHANGES NEEDED ATTM TO THE FLASH FLOOD
WATCH. THE THREAT FOR SEVERE WEATHER STILL APPEARS FAIRLY LOW AND
SHOULD BE CONFINED TO THE SOUTHEAST COUNTIES LATE TONIGHT INTO
WEDNESDAY.
DUNN
&&
.PREV DISCUSSION... /ISSUED 427 AM CST TUE JAN 8 2013/
MODEL GUIDANCE IS IN GOOD AGREEMENT AND NOW OFFERS A REASONABLE
TRACK FEATURING MORE OF A SMOOTH PENDULUM SWING OF THE UPPER LOW
THROUGH NORTHERN MEXICO TONIGHT BEFORE EJECTING NORTHEAST AND OVER
NORTH CENTRAL TEXAS WEDNESDAY EVENING. THE MODELS HAVE BACKED OFF
THE SLOWER/WOBBLY TRACK THAT TOOK THE LOW WELL WEST OF THE CWA.
THIS MEANS THE SYSTEM WILL BE IN AND OUT MORE QUICKLY...AND
TIMING FOR THE HEAVIEST RAINFALL AND MOST ROBUST CONVECTION NOW
LOOKS LIKE TONIGHT AND WEDNESDAY MORNING. THIS ALSO MEANS THE WARM
SECTOR WILL HAVE LESS TIME TO PENETRATE THE CWA WITH THE SEVERE
THREAT RELEGATED TO THE FAR SE ZONES BETWEEN 3 AM AND 9 AM WED.
ISENTROPIC LIFT HAS BEGUN ACROSS NORTH TEXAS AND CLOUDS WILL
CONTINUE TO THICKEN AND LOWER THROUGH THE DAY. SHOWERS AND AREAS
OF DRIZZLE HAVE ALREADY DEVELOPED ACROSS CENTRAL TEXAS. MODEL
SOUNDINGS REVEAL MUCAPE VALUES OF 100 J/KG NORTH TO 500 J/KG SOUTH
FOR PARCELS NEAR 800MB. THIS MEANS A FEW THUNDERSTORMS WILL
DEVELOP ONCE THE ISENTROPIC LIFT BEGINS ON THE 325K SURFACE
WHICH SHOULD OCCUR AFTER 9AM. SHOWERS/STORMS WILL BECOME NUMEROUS
DURING THE DAY AND SPREAD N/NE. IN THE MEANTIME A DEVELOPING
INVERTED SURFACE TROUGH AND LOW CENTER IN SOUTH TEXAS WILL CAUSE
WINDS TO BACK TO THE NORTHEAST. COLD ADVECTION...CLOUDS AND RAIN
WILL KEEP HIGHS IN THE UPPER 40S WEST TO LOW 50S EAST.
ISENTROPIC LIFT INTENSIFIES SUBSTANTIALLY TONIGHT AS LOW LEVEL
WIND FIELDS INCREASE AND BACK TO THE SOUTHEAST. MOISTURE FLUX AND
THETA-E ADVECTION VALUES ARE VERY HIGH. CONSIDERING THE WARM
CONVEYOR BELT WILL BE TAPPING INTO UNSEASONABLY HIGH PRECIPITABLE
WATER VALUES OF ALMOST 2 INCHES IN THE GULF...THIS WILL ALLOW A
WIDESPREAD AREA OF RAIN TO DEVELOP TONIGHT AND PERSIST INTO
WEDNESDAY MORNING ACROSS NORTH TEXAS IN THE COLD SECTOR. WHILE
RAINFALL RATES WILL LIKELY NOT EXCEED AN INCH PER HOUR...THE
CONTINUOUS RAINS SHOULD HELP GENERATE EXCESSIVE RUNOFF. HEAVY RAIN
EVENTS IN THE COLD SEASON TEND TO PRODUCE MORE RUNOFF THAN IN THE
WARM SEASON. MOST VEGETATION IS DORMANT AND THEREFORE IT DOES NOT
TAKE MUCH OF THE RAIN WATER OUT OF THE SOILS. WE ARE OUTLOOKED IN
SLIGHT RISK FOR EXCESSIVE RAINFALL BY HPC AND HAVE ISSUED A FLASH
FLOOD WATCH FOR AREAS WHERE WE EXPECT 2 TO 4 INCHES OF RAIN. THE
METROPLEX IS ON THE EDGE OR JUST NORTHWEST OF THE HEAVY RAIN AXIS
BUT WE BROUGHT THE WATCH INTO TARRANT/DALLAS/COLLIN COUNTIES
BECAUSE THE URBANIZATION IS MORE SENSITIVE TO HEAVY RAINFALL.
CONCERNING THE SEVERE WEATHER THREAT...A LINE OF STORMS SHOULD
FORM IN SOUTH CENTRAL TEXAS THIS EVENING AND MOVE RATHER SLOWLY
TO THE E/NE INTO OUR FAR SOUTH/SOUTHEAST ZONES AFTER 3 AM.
ALTHOUGH THE WARM SECTOR DOES MAKE IT INTO THE SOUTHEAST ZONES
AHEAD OF THE LINE...IT IS AT THE COOLEST TIME OF THE DAY. THIS
WILL LIKELY LIMIT SURFACE BASED CAPE TO LESS THAN 100 J/KG IF
ANYTHING AT ALL. BECAUSE SHEAR WILL BE HIGH...WE WILL HAVE TO
MONITOR THIS CLOSELY...BUT AT THIS TIME THE SEVERE WEATHER THREAT
LOOKS MORE CONDITIONAL THAN PREVIOUS FORECASTS WHICH HAD THE LINE
MOVING IN DURING THE WARMER AFTERNOON HOURS.
PASSAGE OF THE SURFACE TROUGH WILL BE SUCCEEDED BY DRY SLOT ALOFT
WHICH SHOULD END MOST OF THE RAIN FROM WEST TO EAST DURING THE DAY
WEDNESDAY. A FEW ELEVATED SHOWERS WILL REMAIN POSSIBLE WEDNESDAY
EVENING BUT HAVE LOWERED POPS DUE TO THE FASTER TIMING. SOME WRAP
AROUND CLOUDS WILL AFFECT THE NW ZONES THURSDAY...BUT OTHERWISE
GENERALLY FAIR WEATHER WITH WARMER TEMPS DUE TO SW WINDS. FRIDAY
WILL BE SUNNY AND WARMER WITH HIGHS NEAR 70. THE NEXT FRONT WILL
ARRIVE SATURDAY AND BRING A SLIGHT CHANCE OF CONVECTION OVER THE
EASTERN HALF OF THE AREA. TEMPS WILL COOL INTO THE 30S FOR LOWS
SAT NIGHT...WITH THE UPPER LEVEL PATTERN FAVORABLE FOR SEVERAL
DAYS OF COLD ADVECTION INTO NEXT WEEK. HIGH TEMPS WILL BE CHILLY
SUNDAY INTO MID WEEK...GENERALLY IN THE LOW-MID 40S. GFS HAS
BACKED OFF ON PRECIPITATION SUNDAY WHICH IS WHAT THE OTHER MODELS
WERE FORECASTING...HOWEVER THERE IS A LITTLE MORE EVIDENCE THAT WE
WILL CONTEND WITH POSSIBLE WINTRY PRECIPITATION FOR THE MIDDLE OF
NEXT WEEK WHEN THE UPPER LEVEL PATTERN BECOMES MORE FAVORABLE.
TR.92
&&
.CLIMATE...
IN THE DALLAS/FORT WORTH METROPLEX...24-HOUR RAINFALL (MIDDAY
TODAY TO MIDDAY WEDNESDAY) MAY REACH 3 INCHES. WHEN WAS THE LAST
TIME DFW AIRPORT SAW THAT MUCH PRECIPITATION IN A 24 HOUR PERIOD?
APRIL 8, 2012 (EASTER SUNDAY) - 2.23
MARCH 19-20, 2012 - 4.04
JANUARY 24-25, 2012 - 4.27
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 51 47 56 46 60 / 100 100 100 50 10
WACO, TX 52 49 57 45 64 / 100 100 100 30 10
PARIS, TX 52 47 57 51 60 / 90 100 100 80 10
DENTON, TX 50 45 54 45 59 / 100 100 90 60 10
MCKINNEY, TX 51 47 56 47 59 / 100 100 100 60 10
DALLAS, TX 51 47 56 46 60 / 100 100 100 50 10
TERRELL, TX 52 49 57 50 61 / 100 100 100 60 10
CORSICANA, TX 53 51 58 49 63 / 100 100 100 40 10
TEMPLE, TX 53 49 58 45 65 / 100 100 100 30 10
MINERAL WELLS, TX 48 44 54 42 60 / 90 100 80 50 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH FROM 6 PM CST THIS EVENING THROUGH WEDNESDAY
AFTERNOON FOR TXZ094-095-104>107-118>123-133>135-145>148-158>162-
174-175.
&&
$$
/
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1108 AM CST TUE JAN 8 2013
.UPDATE...
CURRENT FORECAST IS IN GOOD SHAPE AND ONLY MADE SOME MINOR CHANGES
TO THE SKY/POP GRIDS TO ACCOUNT FOR CURRENT OBSERVATIONS. CURRENT
ANALYSIS OF AVAILABLE 12Z GUIDANCE CONTINUES TO SHOW THAT
WIDESPREAD HEAVY RAINFALL IS LIKELY THROUGH WEDNESDAY. INITIAL
ACTIVITY HAS BEEN SOMEWHAT SCATTERED AS BROAD ISENTROPIC ASCENT
OVERSPREADS THE AREA. LATEST RAP SOUNDINGS FROM ACROSS NORTH TEXAS
INDICATE ABOUT 100-200J/KG OF ELEVATED INSTABILITY WHICH HAS BEEN
SUFFICIENT FOR ISOLATED THUNDERSTORMS CAPABLE OF PRODUCING SMALL
HAIL. AS DEEPER LARGE SCALE FORCING OVERSPREADS CENTRAL AND NORTH
TEXAS TONIGHT...A WELL DEFINED WARM CONVEYOR BELT WILL BECOME
ESTABLISHED AND AREAL COVERAGE OF PRECIPITATION IS EXPECTED TO
INCREASE. HEAVIEST RAINS STILL EXPECTED OVERNIGHT TONIGHT INTO
EARLY WEDNESDAY...SO NO CHANGES NEEDED ATTM TO THE FLASH FLOOD
WATCH. THE THREAT FOR SEVERE WEATHER STILL APPEARS FAIRLY LOW AND
SHOULD BE CONFINED TO THE SOUTHEAST COUNTIES LATE TONIGHT INTO
WEDNESDAY.
DUNN
&&
.AVIATION...
/12Z TAFS/
CONCERNS...RAIN WITH DETERIORATING CIGS/VSBY...THUNDER POTENTIAL.
CIGS/VSBY...
AT 12Z TAF ISSUANCE TIME...SCATTERED SHOWERS HAVE ALREADY REACHED
AREAS NORTH OF THE I-20 CORRIDOR. AS UPGLIDE INTENSIFIES FURTHER
THIS MORNING...THE ACTIVITY WILL INCREASE IN INTENSITY AND AREAL
COVERAGE. THE RESULTING TOP-DOWN SATURATION WILL RAPIDLY LOWER
CEILINGS...WHICH SHOULD FALL INTO THE IFR CATEGORY BY EARLY
AFTERNOON. VISIBILITY WILL DETERIORATE IN TANDEM BUT WILL REMAIN
VARIABLE WITH INTERMITTENT PRECIPITATION. IFR CONDITIONS WILL
PREVAIL THROUGHOUT THE REMAINDER OF THE EVENT...POTENTIALLY
IMPROVING LATE WEDNESDAY.
THUNDER...
ALTHOUGH INITIAL CONVECTION HAS BEEN LOW-TOPPED SHOWERS...
ENHANCEMENT ACROSS THE HILL COUNTRY IS INDICATIVE OF INCREASING
INSTABILITY THAT WILL SPREAD NORTHWARD TODAY IN WARM ADVECTION
REGIME. TIMING IN TAFS IS BASED ON EARLIER ARRIVAL/IMPACTS AT WACO
THIS MORNING...THEN AFTERNOON THUNDER POTENTIAL AT METRO
TERMINALS.
25
&&
.PREV DISCUSSION... /ISSUED 427 AM CST TUE JAN 8 2013/
MODEL GUIDANCE IS IN GOOD AGREEMENT AND NOW OFFERS A REASONABLE
TRACK FEATURING MORE OF A SMOOTH PENDULUM SWING OF THE UPPER LOW
THROUGH NORTHERN MEXICO TONIGHT BEFORE EJECTING NORTHEAST AND OVER
NORTH CENTRAL TEXAS WEDNESDAY EVENING. THE MODELS HAVE BACKED OFF
THE SLOWER/WOBBLY TRACK THAT TOOK THE LOW WELL WEST OF THE CWA.
THIS MEANS THE SYSTEM WILL BE IN AND OUT MORE QUICKLY...AND
TIMING FOR THE HEAVIEST RAINFALL AND MOST ROBUST CONVECTION NOW
LOOKS LIKE TONIGHT AND WEDNESDAY MORNING. THIS ALSO MEANS THE WARM
SECTOR WILL HAVE LESS TIME TO PENETRATE THE CWA WITH THE SEVERE
THREAT RELEGATED TO THE FAR SE ZONES BETWEEN 3 AM AND 9 AM WED.
ISENTROPIC LIFT HAS BEGUN ACROSS NORTH TEXAS AND CLOUDS WILL
CONTINUE TO THICKEN AND LOWER THROUGH THE DAY. SHOWERS AND AREAS
OF DRIZZLE HAVE ALREADY DEVELOPED ACROSS CENTRAL TEXAS. MODEL
SOUNDINGS REVEAL MUCAPE VALUES OF 100 J/KG NORTH TO 500 J/KG SOUTH
FOR PARCELS NEAR 800MB. THIS MEANS A FEW THUNDERSTORMS WILL
DEVELOP ONCE THE ISENTROPIC LIFT BEGINS ON THE 325K SURFACE
WHICH SHOULD OCCUR AFTER 9AM. SHOWERS/STORMS WILL BECOME NUMEROUS
DURING THE DAY AND SPREAD N/NE. IN THE MEANTIME A DEVELOPING
INVERTED SURFACE TROUGH AND LOW CENTER IN SOUTH TEXAS WILL CAUSE
WINDS TO BACK TO THE NORTHEAST. COLD ADVECTION...CLOUDS AND RAIN
WILL KEEP HIGHS IN THE UPPER 40S WEST TO LOW 50S EAST.
ISENTROPIC LIFT INTENSIFIES SUBSTANTIALLY TONIGHT AS LOW LEVEL
WIND FIELDS INCREASE AND BACK TO THE SOUTHEAST. MOISTURE FLUX AND
THETA-E ADVECTION VALUES ARE VERY HIGH. CONSIDERING THE WARM
CONVEYOR BELT WILL BE TAPPING INTO UNSEASONABLY HIGH PRECIPITABLE
WATER VALUES OF ALMOST 2 INCHES IN THE GULF...THIS WILL ALLOW A
WIDESPREAD AREA OF RAIN TO DEVELOP TONIGHT AND PERSIST INTO
WEDNESDAY MORNING ACROSS NORTH TEXAS IN THE COLD SECTOR. WHILE
RAINFALL RATES WILL LIKELY NOT EXCEED AN INCH PER HOUR...THE
CONTINUOUS RAINS SHOULD HELP GENERATE EXCESSIVE RUNOFF. HEAVY RAIN
EVENTS IN THE COLD SEASON TEND TO PRODUCE MORE RUNOFF THAN IN THE
WARM SEASON. MOST VEGETATION IS DORMANT AND THEREFORE IT DOES NOT
TAKE MUCH OF THE RAIN WATER OUT OF THE SOILS. WE ARE OUTLOOKED IN
SLIGHT RISK FOR EXCESSIVE RAINFALL BY HPC AND HAVE ISSUED A FLASH
FLOOD WATCH FOR AREAS WHERE WE EXPECT 2 TO 4 INCHES OF RAIN. THE
METROPLEX IS ON THE EDGE OR JUST NORTHWEST OF THE HEAVY RAIN AXIS
BUT WE BROUGHT THE WATCH INTO TARRANT/DALLAS/COLLIN COUNTIES
BECAUSE THE URBANIZATION IS MORE SENSITIVE TO HEAVY RAINFALL.
CONCERNING THE SEVERE WEATHER THREAT...A LINE OF STORMS SHOULD
FORM IN SOUTH CENTRAL TEXAS THIS EVENING AND MOVE RATHER SLOWLY
TO THE E/NE INTO OUR FAR SOUTH/SOUTHEAST ZONES AFTER 3 AM.
ALTHOUGH THE WARM SECTOR DOES MAKE IT INTO THE SOUTHEAST ZONES
AHEAD OF THE LINE...IT IS AT THE COOLEST TIME OF THE DAY. THIS
WILL LIKELY LIMIT SURFACE BASED CAPE TO LESS THAN 100 J/KG IF
ANYTHING AT ALL. BECAUSE SHEAR WILL BE HIGH...WE WILL HAVE TO
MONITOR THIS CLOSELY...BUT AT THIS TIME THE SEVERE WEATHER THREAT
LOOKS MORE CONDITIONAL THAN PREVIOUS FORECASTS WHICH HAD THE LINE
MOVING IN DURING THE WARMER AFTERNOON HOURS.
PASSAGE OF THE SURFACE TROUGH WILL BE SUCCEEDED BY DRY SLOT ALOFT
WHICH SHOULD END MOST OF THE RAIN FROM WEST TO EAST DURING THE DAY
WEDNESDAY. A FEW ELEVATED SHOWERS WILL REMAIN POSSIBLE WEDNESDAY
EVENING BUT HAVE LOWERED POPS DUE TO THE FASTER TIMING. SOME WRAP
AROUND CLOUDS WILL AFFECT THE NW ZONES THURSDAY...BUT OTHERWISE
GENERALLY FAIR WEATHER WITH WARMER TEMPS DUE TO SW WINDS. FRIDAY
WILL BE SUNNY AND WARMER WITH HIGHS NEAR 70. THE NEXT FRONT WILL
ARRIVE SATURDAY AND BRING A SLIGHT CHANCE OF CONVECTION OVER THE
EASTERN HALF OF THE AREA. TEMPS WILL COOL INTO THE 30S FOR LOWS
SAT NIGHT...WITH THE UPPER LEVEL PATTERN FAVORABLE FOR SEVERAL
DAYS OF COLD ADVECTION INTO NEXT WEEK. HIGH TEMPS WILL BE CHILLY
SUNDAY INTO MID WEEK...GENERALLY IN THE LOW-MID 40S. GFS HAS
BACKED OFF ON PRECIPITATION SUNDAY WHICH IS WHAT THE OTHER MODELS
WERE FORECASTING...HOWEVER THERE IS A LITTLE MORE EVIDENCE THAT WE
WILL CONTEND WITH POSSIBLE WINTRY PRECIPITATION FOR THE MIDDLE OF
NEXT WEEK WHEN THE UPPER LEVEL PATTERN BECOMES MORE FAVORABLE.
TR.92
&&
.CLIMATE...
IN THE DALLAS/FORT WORTH METROPLEX...24-HOUR RAINFALL (MIDDAY
TODAY TO MIDDAY WEDNESDAY) MAY REACH 3 INCHES. WHEN WAS THE LAST
TIME DFW AIRPORT SAW THAT MUCH PRECIPITATION IN A 24 HOUR PERIOD?
APRIL 8, 2012 (EASTER SUNDAY) - 2.23
MARCH 19-20, 2012 - 4.04
JANUARY 24-25, 2012 - 4.27
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 51 47 56 46 60 / 100 100 100 50 10
WACO, TX 52 49 57 45 64 / 100 100 100 30 10
PARIS, TX 52 47 57 51 60 / 90 100 100 80 10
DENTON, TX 50 45 54 45 59 / 100 100 90 60 10
MCKINNEY, TX 51 47 56 47 59 / 100 100 100 60 10
DALLAS, TX 51 47 56 46 60 / 100 100 100 50 10
TERRELL, TX 52 49 57 50 61 / 100 100 100 60 10
CORSICANA, TX 53 51 58 49 63 / 100 100 100 40 10
TEMPLE, TX 53 49 58 45 65 / 100 100 100 30 10
MINERAL WELLS, TX 48 44 54 42 60 / 90 100 80 50 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH FROM 6 PM CST THIS EVENING THROUGH WEDNESDAY
AFTERNOON FOR TXZ094-095-104>107-118>123-133>135-145>148-158>162-
174-175.
&&
$$
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1032 PM MST WED JAN 9 2013
.AVIATION...
VFR CONDITIONS ARE EXPECTED AT KCOS AND KPUB THROUGH 06Z SATURDAY.
WINDS WILL REMAIN LIGHT AND VARIABLE OVERNIGHT AND THROUGH MUCH OF
THURSDAY MORNING.
KALS WILL LIKELY SEE SCT001 WITH ISOLATED BKN001 SKIES EARLY
THURSDAY MORNING WITH ONLY LOCAL IFR/LIFR CIGS POSSIBLE FROM 09Z
TO 15Z. -PJC
&&
.PREV DISCUSSION... /ISSUED 958 PM MST WED JAN 9 2013/
UPDATE...
UPDATED THE GRIDS TO LOWER TEMPERATURES IN THE SAN LUIS VALLEY AS
SKIES WILL REMAIN CLEAR FOR THE NEXT FEW HOURS. CLEAR SKIES AND
SNOW COVER WILL ALLOW TEMPERATURES TO FALL TO NEAR -20F BEFORE
HIGH CLOUDS MOVE OVERHEAD EARLY FRIDAY MORNING. -PJC
PREV DISCUSSION... /ISSUED 247 PM MST WED JAN 9 2013/
SHORT TERM...
(TONIGHT AND TOMORROW)
.MAIN SHORT TERM CONCERN IS THE CHANCE OF RAIN AND FREEZING RAIN
ACROSS THE FAR SE PLAINS...
CURRENT WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS INDICATING WEAK
MAINLY WESTERLY FLOW ALOFT ACROSS THE AREA WITH A LARGE UPPER LOW
STILL SPINNING ACROSS NORTHEASTERN MEXICO JUST SOUTH AND WEST OF DEL
RIO TEXAS AT THIS TIME. WATER VAPOR IMAGERY INDICATING MID AND UPPER
LEVEL MOISTURE ASSOCIATED WITH THIS SYSTEM SPREADING NORTH INTO
EASTERN NEW MEXICO AND WESTERN TEXAS...WITH MID AND UPPER LEVEL
MOISTURE ALSO SPREADING INTO THE GREAT BASIN REGION AHEAD OF A
DEVELOPING STORM SYSTEM MOVING ONSHORE ACROSS THE PAC NW COAST AT
THIS TIME. WITH THE LIGHT WINDS...TEMPERATURES HAVE STRUGGLED TO
WARM WITH READINGS IN THE MID 40S TO LOWER 50S ACROSS THE LOWER
ELEVATIONS AND 20S AND 30S ACROSS THE HIGHER ELEVATIONS. TEMPS IN
THE SAN LUIS VALLEY CONTINUE TO LAG BEHIND WITH READINGS MAINLY IN
THE TEENS AND 20S...WITH THE COLDEST READINGS IN THE CENTRAL
PORTIONS OF THE VALLEY.
TONIGHT...MODELS STILL DIFFER ON LOCATION OF EJECTING LOW WITH THE
12Z GFS AND EC THE FURTHEST NORTH AND WEST WITH THE LOW NORTH OF
ABILENE TEXAS AT 12Z THU...WHERE AS THE HIGHER RES NAM AND RAP KEEP
THE LOW FURTHER SOUTH AND EAST. THE FURTHER NORTH SOLUTIONS OF THE
EC AND ESPECIALLY THE GFS ARE INDICATING STRONGER MID LEVEL WAA
ACROSS THE WESTERN TX AND OKLAHOMA PANHANDLE THROUGH EASTERN
COLORADO AND WESTERN KANSAS AND ARE PRINTING OUT MORE QPF ACROSS THE
FAR SOUTHEAST PLAINS AS A RESULT. THE HIGHER RES MODELS KEEP THE
BEST LIFT AND WAA FURTHER EAST ACROSS WESTERN AND CENTRAL KANSAS
WHICH IS ALSO SUPPORTED BY LOCAL HIGH RES WRF MODEL. WITH THAT
SAID...HAVE KEPT CURRENT FORECAST TRENDED TOWARDS THE HIGHER RES
MODELS KEEPING SILENT POPS THROUGH 06Z WITH CHANCE POPS ACROSS
EASTERN PORTIONS OF BACA AND PROWERS COUNTIES AND SLIGHT POPS
FURTHER NORTH AND WEST INTO KIOWA AND WESTERN PROWERS AND BACA
COUNTIES THEREAFTER. SOUNDINGS INDICATING MAINLY LIGHT RAIN ACROSS
BACA COUNTY THOUGH DO INDICATE A BRIEF PERIOD OF LIGHT FREEZING RAIN
POSSIBLE ACROSS PROWERS AND KIOWA COUNTIES...WITH LATER SHIFTS
NEEDING TO MONITOR LATEST MODELS AND TRENDS. ELSEWHERE...WEAK
WESTERLY FLOW THIS EVENING BECOMES MORE SOUTHWEST AND SLOWLY
INCREASES OVERNIGHT AS EASTERN PACIFIC SYSTEM CONTINUES TO MOVE
ONSHORE ACROSS THE WEST COAST. MAINLY CLEAR SKIES WEST OF THE PLAINS
WILL HELP COOL TEMPS ONCE AGAIN IN THE SAN LUIS VALLEY...WITH THE
WARMEST READINGS EXPECTED ACROSS THE HIGHER TERRAIN ALONG AND WEST
OF THE I-25 CORRIDOR WHERE LEE TROUGHING DEVELOPS OVERNIGHT.
TOMORROW...SOUTHWEST FLOW ALOFT CONTINUES TO INCREASE THROUGH THE
DAY AS THE WEST COAST SYSTEM TRANSLATES INTO THE GREAT BASIN.
MOISTURE PROGGED TO INCREASE FROM WEST TO EAST AND WITH INCREASING
OROGRAPHICS COULD SEE SOME LIGHT SNOW DEVELOPING ACROSS THE HIGHER
TERRAIN OF THE SOUTHWEST MTS BY THE LATE AFTERNOON. LEE TROUGHING
STRENGTHENS ACROSS THE I-25 CORRIDOR WITH BREEZY SOUTH TO SOUTHWEST
WINDS DEVELOPING ACROSS THE PLAINS BOOSTING TEMPS INTO THE LOWER TO
MID 50S. INCREASING CLOUDS AND SLIGHT COOLING ALOFT WILL LEAD TO
SLIGHTLY COOLER TEMPS ACROSS THE HIGHER TERRAIN AND HIGH VALLEYS.
LONG TERM...
(THURSDAY NIGHT THROUGH WEDNESDAY)
.HIGH IMPACT WEATHER TO AFFECT PORTIONS OF SOUTH CENTRAL AND
SOUTHEAST COLORADO THURSDAY NIGHT THROUGH FRIDAY...WITH A TURN
TOWARDS MUCH COLDER TEMPERATURES THROUGH THE WEEKEND INTO EARLY NEXT
WEEK...
A CLOSED UPPER LOW CARVES OUT ACROSS THE GREAT BASIN THURSDAY NIGHT
SENDING STRONG SOUTHWEST FLOW...WITH 110-120+ KT UPPER JET ACROSS
COLORADO BY 12Z FRIDAY. MOISTURE DEEPENS ALONG THE CONTINENTAL
DIVIDE THURSDAY EVENING...WITH SNOW RAMPING UP ALONG THE
OROGRAPHICALLY FAVORED EASTERN SAN JUAN MOUNTAINS. COMBINED WITH
MTN TOP WINDS OF 50-60 KTS...HAZARDOUS CONDITIONS WILL BE POSSIBLE
DUE TO WHITE OUT CONDITIONS IN BLOWING SNOW ACROSS ZONE 68...WHICH
INCLUDES THE WOLF CREEK PASS. HAVE UPGRADED THE WINTER STORM WATCH
TO A BLIZZARD WATCH FOR THIS ZONE. SNOW SHOULD SPREAD NORTH AND
EASTWARD AFTER MIDNIGHT THROUGH THE MORNING HOURS...WITH THE
HEAVIEST SNOW EXPECTED TO FALL BEFORE 18Z WHEN BEST FORCING MOVES
THROUGH. WINDS THEN SHIFT MORE FROM THE WEST TO NORTHWEST FRIDAY
AFTERNOON...WITH THE FOCUS FOR SNOW SHIFTING INTO THE EASTERN
SAWATCH AND WESTERN MOSQUITO RANGES DURING THE AFTERNOON. OVERALL
SNOWFALL AMOUNTS FOR THE BRUNT OF THE EVENT...THURS
NIGHT/FRI...SHOULD RANGE FROM 8 TO 17 INCHES ACROSS THE EASTERN SAN
JUAN MOUNTAINS...WITH AROUND 5 TO 10 INCHES WITH LOCALLY UP TO A
FOOT FOR THE LA GARITAS...EASTERN SAWATCH AND WESTERN MOSQUITO
RANGES. THINK THAT THESE LATTER AREAS WILL EVENTUALLY NEED A WINTER
WEATHER ADVISORY...BUT SINCE SNOW AMOUNTS HAVE BEEN CONSISTENTLY
COMING UP SHORT OF WARNING NUMBERS (12" OR MORE IN GREATER THAN 12
HOURS)...NO WATCHES WILL BE ISSUED AT THIS POINT.
AS THE UPPER JET TRANSLATES ACROSS THE AREA THURSDAY NIGHT THROUGH
FRIDAY...A BORA COLD FRONT WILL MOVE FROM WEST TO EAST ACROSS THE
REGION. HIGHER PEAKS SHOULD START BLOWING FIRST AS MTN TOP WINDS
INCREASE TO AROUND 50-60 KTS. THERE IS QUITE A BIT OF FORWARD SHEAR
WITH THIS SYSTEM...SO THIS DOESN`T APPEAR TO BE A MTN WAVE EVENT.
HOWEVER AS THE NORTH-SOUTH ORIENTED COLD FRONT CROSSES THE
MOUNTAINS...IT COULD BRING A PERIOD OF STRONG GUSTY WINDS INTO THE
ADJACENT LOWER ELEVATIONS OF THE SAN LUIS VALLEY AND THE I-25
CORRIDOR EARLY FRIDAY MORNING AS COLD DENSE AIR SPILLS OVER THE
MOUNTAINS. SFC PRESSURE GRADIENT IS IMPRESSIVE FRIDAY MORNING AS
THE SURFACE LOW DEEPENS ACROSS NORTHEAST COLORADO WHICH SHOULD ALSO
AID IN MIXING STRONG WINDS ALOFT TO THE SURFACE ACROSS THE REMAINDER
OF THE SOUTHEAST PLAINS. ALREADY HAVE A HIGH WIND WATCH OUT AND PLAN TO
MAINTAIN IT. DID BUMP UP THE START TIME OF THE HIGH WIND WATCH TO
MIDNIGHT ACROSS THE SOUTHEAST MTS AS WINDS ALOFT WILL BE INCREASING
AFTER MIDNIGHT...THOUGH THINK STRONGER GUSTS WILL STAY ACROSS THE
HIGHER ELEVATIONS UNTIL FRIDAY MORNING WHEN THE FRONT MOVES THROUGH. WINDS
MAY COME UP JUST SHY OF HIGH WIND CRITERIA ACROSS CENTER PORTIONS OF
THE SAN LUIS VALLEY...BUT VALLEY EDGES...PARTICULARLY ON THE WESTERN
SIDE COULD SEE A PERIOD OF HIGH WINDS FRIDAY MORNING.
BROAD TROFFING REMAINS ACROSS THE GREAT BASIN AND ROCKIES REGION
THROUGH EARLY NEXT WEEK AS ENERGY CONTINUES TO DROP SOUTHWARD OUT OF
CANADA. THIS WILL KEEP VERY COLD AND GENERALLY UNSETTLED CONDITIONS
ACROSS THE REGION THROUGH EARLY NEXT WEEK. TEMPERATURES WILL DROP
OFF CONSIDERABLY ACROSS THE PLAINS...WITH HIGHS STRUGGLING TO REACH
THE 30S BY THE MIDDLE OF NEXT WEEK. MEANWHILE...THE MOUNTAINS AND
VALLEYS WILL BE DROPPING INTO THE NEGATIVE DIGITS AT NIGHT...WITH
KALS LIKELY TO HIT -30 OR BELOW AS A NEW BATCH OF COLD AIR GETS
ENTRENCHED IN THE VALLEY. NEXT WAVE OF ENERGY LIFTS OUT OF THE MEAN
TROF ACROSS SOUTHERN PORTIONS OF THE AREA SAT NIGHT...AND WITH
SHALLOW UPSLOPE AND COLD AIR...WE COULD SEE SOME ADDITIONAL LIGHT
SNOW ACROSS THE MOUNTAINS AND ADJACENT PLAINS...BUT EACH SUCCESSIVE
MODEL RUN HAS BEEN DRIER...SO WILL LEAVE THE SILENT POPS ACROSS THE
PLAINS...WITH GENERALLY ISOLATED TO LOW END SCATTERED POPS ACROSS
THE MOUNTAINS. SAME THING HAPPENS FOR MONDAY NIGHT AS ANOTHER WAVE
OF ENERGY DROPPING INTO THE BASE OF THE TROF CLOSES OFF AN UPPER LOW
ACROSS THE DESSERT SOUTHWEST AND LEADING SHORTWAVE ENERGY EJECTS TO
THE NORTHEAST ACROSS THE AREA. ONCE AGAIN...IF IT OCCURS...ANY
SNOWFALL ACCUMULATIONS APPEAR TO REMAIN LIGHT. GFS AND ECMWF ORPHAN THE
UPPER LOW ACROSS EXTREME SOUTHERN AZ/NRN OLD MEXICO THROUGH
WEDNESDAY WHICH IS TOO FAR SOUTH TO BRING ANY PRECIPITATION TO THE
AREA THROUGH WEDNESDAY. TEMPERATURES SHOULD SLOWLY MODERATE SOME
INTO THE MIDDLE OF NEXT WEEK. -KT
AVIATION...
VFR CONDITIONS TO PREVAIL AT KCOS AND KPUB THROUGH THE NEXT 24
HOURS WITH GENERALLY LIGHT WINDS THROUGH TONIGHT. BREEZY SOUTH TO
SOUTHWEST WINDS OF 15-20KTS ARE EXPECTED TO DEVELOP AFT 18Z THU.
KALS HAD STRONG RADIATIONAL COOLING AND SCT001 TO LOCALLY BKN001
ACROSS THE VALLEY FLOOR LATE LAST NIGHT AND EARLY THIS MORNING...BUT
VIS DID NOT DROP BELOW MFVR. WOULD THINK THE SAME FOR TONIGHT...AS
TEMPS DID NOT WARM AS MUCH AS EXPECTED. AT ANY RATE...VFR CONDITIONS
EXPECTED THROUGH 06Z THU...WITH LOCAL IFR AND LIFR CIGS THEN
POSSIBLE THROUGH 16Z. VFR AGAIN AFT 16Z THU. -MW
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM FRIDAY MORNING THROUGH FRIDAY AFTERNOON FOR
COZ069>071-083>089-093>099.
HIGH WIND WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY
AFTERNOON FOR COZ072>082.
BLIZZARD WATCH FROM THURSDAY EVENING THROUGH FRIDAY AFTERNOON
FOR COZ068.
&&
$$
81/10
AREA FORECAST DISCUSSION
NWS PUEBLO CO
958 PM MST WED JAN 9 2013
.UPDATE...
UPDATED THE GRIDS TO LOWER TEMPERATURES IN THE SAN LUIS VALLEY AS
SKIES WILL REMAIN CLEAR FOR THE NEXT FEW HOURS. CLEAR SKIES AND
SNOW COVER WILL ALLOW TEMPERATURES TO FALL TO NEAR -20F BEFORE
HIGH CLOUDS MOVE OVERHEAD EARLY FRIDAY MORNING. -PJC
&&
.PREV DISCUSSION... /ISSUED 247 PM MST WED JAN 9 2013/
SHORT TERM...
(TONIGHT AND TOMORROW)
..MAIN SHORT TERM CONCERN IS THE CHANCE OF RAIN AND FREEZING RAIN
ACROSS THE FAR SE PLAINS...
CURRENT WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS INDICATING WEAK
MAINLY WESTERLY FLOW ALOFT ACROSS THE AREA WITH A LARGE UPPER LOW
STILL SPINNING ACROSS NORTHEASTERN MEXICO JUST SOUTH AND WEST OF DEL
RIO TEXAS AT THIS TIME. WATER VAPOR IMAGERY INDICATING MID AND UPPER
LEVEL MOISTURE ASSOCIATED WITH THIS SYSTEM SPREADING NORTH INTO
EASTERN NEW MEXICO AND WESTERN TEXAS...WITH MID AND UPPER LEVEL
MOISTURE ALSO SPREADING INTO THE GREAT BASIN REGION AHEAD OF A
DEVELOPING STORM SYSTEM MOVING ONSHORE ACROSS THE PAC NW COAST AT
THIS TIME. WITH THE LIGHT WINDS...TEMPERATURES HAVE STRUGGLED TO
WARM WITH READINGS IN THE MID 40S TO LOWER 50S ACROSS THE LOWER
ELEVATIONS AND 20S AND 30S ACROSS THE HIGHER ELEVATIONS. TEMPS IN
THE SAN LUIS VALLEY CONTINUE TO LAG BEHIND WITH READINGS MAINLY IN
THE TEENS AND 20S...WITH THE COLDEST READINGS IN THE CENTRAL
PORTIONS OF THE VALLEY.
TONIGHT...MODELS STILL DIFFER ON LOCATION OF EJECTING LOW WITH THE
12Z GFS AND EC THE FURTHEST NORTH AND WEST WITH THE LOW NORTH OF
ABILENE TEXAS AT 12Z THU...WHERE AS THE HIGHER RES NAM AND RAP KEEP
THE LOW FURTHER SOUTH AND EAST. THE FURTHER NORTH SOLUTIONS OF THE
EC AND ESPECIALLY THE GFS ARE INDICATING STRONGER MID LEVEL WAA
ACROSS THE WESTERN TX AND OKLAHOMA PANHANDLE THROUGH EASTERN
COLORADO AND WESTERN KANSAS AND ARE PRINTING OUT MORE QPF ACROSS THE
FAR SOUTHEAST PLAINS AS A RESULT. THE HIGHER RES MODELS KEEP THE
BEST LIFT AND WAA FURTHER EAST ACROSS WESTERN AND CENTRAL KANSAS
WHICH IS ALSO SUPPORTED BY LOCAL HIGH RES WRF MODEL. WITH THAT
SAID...HAVE KEPT CURRENT FORECAST TRENDED TOWARDS THE HIGHER RES
MODELS KEEPING SILENT POPS THROUGH 06Z WITH CHANCE POPS ACROSS
EASTERN PORTIONS OF BACA AND PROWERS COUNTIES AND SLIGHT POPS
FURTHER NORTH AND WEST INTO KIOWA AND WESTERN PROWERS AND BACA
COUNTIES THEREAFTER. SOUNDINGS INDICATING MAINLY LIGHT RAIN ACROSS
BACA COUNTY THOUGH DO INDICATE A BRIEF PERIOD OF LIGHT FREEZING RAIN
POSSIBLE ACROSS PROWERS AND KIOWA COUNTIES...WITH LATER SHIFTS
NEEDING TO MONITOR LATEST MODELS AND TRENDS. ELSEWHERE...WEAK
WESTERLY FLOW THIS EVENING BECOMES MORE SOUTHWEST AND SLOWLY
INCREASES OVERNIGHT AS EASTERN PACIFIC SYSTEM CONTINUES TO MOVE
ONSHORE ACROSS THE WEST COAST. MAINLY CLEAR SKIES WEST OF THE PLAINS
WILL HELP COOL TEMPS ONCE AGAIN IN THE SAN LUIS VALLEY...WITH THE
WARMEST READINGS EXPECTED ACROSS THE HIGHER TERRAIN ALONG AND WEST
OF THE I-25 CORRIDOR WHERE LEE TROUGHING DEVELOPS OVERNIGHT.
TOMORROW...SOUTHWEST FLOW ALOFT CONTINUES TO INCREASE THROUGH THE
DAY AS THE WEST COAST SYSTEM TRANSLATES INTO THE GREAT BASIN.
MOISTURE PROGGED TO INCREASE FROM WEST TO EAST AND WITH INCREASING
OROGRAPHICS COULD SEE SOME LIGHT SNOW DEVELOPING ACROSS THE HIGHER
TERRAIN OF THE SOUTHWEST MTS BY THE LATE AFTERNOON. LEE TROUGHING
STRENGTHENS ACROSS THE I-25 CORRIDOR WITH BREEZY SOUTH TO SOUTHWEST
WINDS DEVELOPING ACROSS THE PLAINS BOOSTING TEMPS INTO THE LOWER TO
MID 50S. INCREASING CLOUDS AND SLIGHT COOLING ALOFT WILL LEAD TO
SLIGHTLY COOLER TEMPS ACROSS THE HIGHER TERRAIN AND HIGH VALLEYS.
LONG TERM...
(THURSDAY NIGHT THROUGH WEDNESDAY)
..HIGH IMPACT WEATHER TO AFFECT PORTIONS OF SOUTH CENTRAL AND
SOUTHEAST COLORADO THURSDAY NIGHT THROUGH FRIDAY...WITH A TURN
TOWARDS MUCH COLDER TEMPERATURES THROUGH THE WEEKEND INTO EARLY NEXT
WEEK...
A CLOSED UPPER LOW CARVES OUT ACROSS THE GREAT BASIN THURSDAY NIGHT
SENDING STRONG SOUTHWEST FLOW...WITH 110-120+ KT UPPER JET ACROSS
COLORADO BY 12Z FRIDAY. MOISTURE DEEPENS ALONG THE CONTINENTAL
DIVIDE THURSDAY EVENING...WITH SNOW RAMPING UP ALONG THE
OROGRAPHICALLY FAVORED EASTERN SAN JUAN MOUNTAINS. COMBINED WITH
MTN TOP WINDS OF 50-60 KTS...HAZARDOUS CONDITIONS WILL BE POSSIBLE
DUE TO WHITE OUT CONDITIONS IN BLOWING SNOW ACROSS ZONE 68...WHICH
INCLUDES THE WOLF CREEK PASS. HAVE UPGRADED THE WINTER STORM WATCH
TO A BLIZZARD WATCH FOR THIS ZONE. SNOW SHOULD SPREAD NORTH AND
EASTWARD AFTER MIDNIGHT THROUGH THE MORNING HOURS...WITH THE
HEAVIEST SNOW EXPECTED TO FALL BEFORE 18Z WHEN BEST FORCING MOVES
THROUGH. WINDS THEN SHIFT MORE FROM THE WEST TO NORTHWEST FRIDAY
AFTERNOON...WITH THE FOCUS FOR SNOW SHIFTING INTO THE EASTERN
SAWATCH AND WESTERN MOSQUITO RANGES DURING THE AFTERNOON. OVERALL
SNOWFALL AMOUNTS FOR THE BRUNT OF THE EVENT...THURS
NIGHT/FRI...SHOULD RANGE FROM 8 TO 17 INCHES ACROSS THE EASTERN SAN
JUAN MOUNTAINS...WITH AROUND 5 TO 10 INCHES WITH LOCALLY UP TO A
FOOT FOR THE LA GARITAS...EASTERN SAWATCH AND WESTERN MOSQUITO
RANGES. THINK THAT THESE LATTER AREAS WILL EVENTUALLY NEED A WINTER
WEATHER ADVISORY...BUT SINCE SNOW AMOUNTS HAVE BEEN CONSISTENTLY
COMING UP SHORT OF WARNING NUMBERS (12" OR MORE IN GREATER THAN 12
HOURS)...NO WATCHES WILL BE ISSUED AT THIS POINT.
AS THE UPPER JET TRANSLATES ACROSS THE AREA THURSDAY NIGHT THROUGH
FRIDAY...A BORA COLD FRONT WILL MOVE FROM WEST TO EAST ACROSS THE
REGION. HIGHER PEAKS SHOULD START BLOWING FIRST AS MTN TOP WINDS
INCREASE TO AROUND 50-60 KTS. THERE IS QUITE A BIT OF FORWARD SHEAR
WITH THIS SYSTEM...SO THIS DOESN`T APPEAR TO BE A MTN WAVE EVENT.
HOWEVER AS THE NORTH-SOUTH ORIENTED COLD FRONT CROSSES THE
MOUNTAINS...IT COULD BRING A PERIOD OF STRONG GUSTY WINDS INTO THE
ADJACENT LOWER ELEVATIONS OF THE SAN LUIS VALLEY AND THE I-25
CORRIDOR EARLY FRIDAY MORNING AS COLD DENSE AIR SPILLS OVER THE
MOUNTAINS. SFC PRESSURE GRADIENT IS IMPRESSIVE FRIDAY MORNING AS
THE SURFACE LOW DEEPENS ACROSS NORTHEAST COLORADO WHICH SHOULD ALSO
AID IN MIXING STRONG WINDS ALOFT TO THE SURFACE ACROSS THE REMAINDER
OF THE SOUTHEAST PLAINS. ALREADY HAVE A HIGH WIND WATCH OUT AND PLAN TO
MAINTAIN IT. DID BUMP UP THE START TIME OF THE HIGH WIND WATCH TO
MIDNIGHT ACROSS THE SOUTHEAST MTS AS WINDS ALOFT WILL BE INCREASING
AFTER MIDNIGHT...THOUGH THINK STRONGER GUSTS WILL STAY ACROSS THE
HIGHER ELEVATIONS UNTIL FRIDAY MORNING WHEN THE FRONT MOVES THROUGH. WINDS
MAY COME UP JUST SHY OF HIGH WIND CRITERIA ACROSS CENTER PORTIONS OF
THE SAN LUIS VALLEY...BUT VALLEY EDGES...PARTICULARLY ON THE WESTERN
SIDE COULD SEE A PERIOD OF HIGH WINDS FRIDAY MORNING.
BROAD TROFFING REMAINS ACROSS THE GREAT BASIN AND ROCKIES REGION
THROUGH EARLY NEXT WEEK AS ENERGY CONTINUES TO DROP SOUTHWARD OUT OF
CANADA. THIS WILL KEEP VERY COLD AND GENERALLY UNSETTLED CONDITIONS
ACROSS THE REGION THROUGH EARLY NEXT WEEK. TEMPERATURES WILL DROP
OFF CONSIDERABLY ACROSS THE PLAINS...WITH HIGHS STRUGGLING TO REACH
THE 30S BY THE MIDDLE OF NEXT WEEK. MEANWHILE...THE MOUNTAINS AND
VALLEYS WILL BE DROPPING INTO THE NEGATIVE DIGITS AT NIGHT...WITH
KALS LIKELY TO HIT -30 OR BELOW AS A NEW BATCH OF COLD AIR GETS
ENTRENCHED IN THE VALLEY. NEXT WAVE OF ENERGY LIFTS OUT OF THE MEAN
TROF ACROSS SOUTHERN PORTIONS OF THE AREA SAT NIGHT...AND WITH
SHALLOW UPSLOPE AND COLD AIR...WE COULD SEE SOME ADDITIONAL LIGHT
SNOW ACROSS THE MOUNTAINS AND ADJACENT PLAINS...BUT EACH SUCCESSIVE
MODEL RUN HAS BEEN DRIER...SO WILL LEAVE THE SILENT POPS ACROSS THE
PLAINS...WITH GENERALLY ISOLATED TO LOW END SCATTERED POPS ACROSS
THE MOUNTAINS. SAME THING HAPPENS FOR MONDAY NIGHT AS ANOTHER WAVE
OF ENERGY DROPPING INTO THE BASE OF THE TROF CLOSES OFF AN UPPER LOW
ACROSS THE DESSERT SOUTHWEST AND LEADING SHORTWAVE ENERGY EJECTS TO
THE NORTHEAST ACROSS THE AREA. ONCE AGAIN...IF IT OCCURS...ANY
SNOWFALL ACCUMULATIONS APPEAR TO REMAIN LIGHT. GFS AND ECMWF ORPHAN THE
UPPER LOW ACROSS EXTREME SOUTHERN AZ/NRN OLD MEXICO THROUGH
WEDNESDAY WHICH IS TOO FAR SOUTH TO BRING ANY PRECIPITATION TO THE
AREA THROUGH WEDNESDAY. TEMPERATURES SHOULD SLOWLY MODERATE SOME
INTO THE MIDDLE OF NEXT WEEK. -KT
AVIATION...
VFR CONDITIONS TO PREVAIL AT KCOS AND KPUB THROUGH THE NEXT 24
HOURS WITH GENERALLY LIGHT WINDS THROUGH TONIGHT. BREEZY SOUTH TO
SOUTHWEST WINDS OF 15-20KTS ARE EXPECTED TO DEVELOP AFT 18Z THU.
KALS HAD STRONG RADIATIONAL COOLING AND SCT001 TO LOCALLY BKN001
ACROSS THE VALLEY FLOOR LATE LAST NIGHT AND EARLY THIS MORNING...BUT
VIS DID NOT DROP BELOW MFVR. WOULD THINK THE SAME FOR TONIGHT...AS
TEMPS DID NOT WARM AS MUCH AS EXPECTED. AT ANY RATE...VFR CONDITIONS
EXPECTED THROUGH 06Z THU...WITH LOCAL IFR AND LIFR CIGS THEN
POSSIBLE THROUGH 16Z. VFR AGAIN AFT 16Z THU. -MW
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM FRIDAY MORNING THROUGH FRIDAY AFTERNOON FOR
COZ069>071-083>089-093>099.
HIGH WIND WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY
AFTERNOON FOR COZ072>082.
BLIZZARD WATCH FROM THURSDAY EVENING THROUGH FRIDAY AFTERNOON
FOR COZ068.
&&
$$
81/10
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1227 AM EST THU JAN 10 2013
...Updated Aviation Discussion...
.Forecast Update...
Issued 1105 PM EST Wed Jan 9 2013
After consulting with JKL, have gone ahead and upgraded to a Dense
Fog Advisory for our eastern edge for the rest of the night.
Issued 1019 PM EST Wed Jan 9 2013
Social media communications and surface obs show that the fog in the
Blue Grass has become thicker and more dense in spots, so have
introduced patchy dense fog (in addition to the patchy fog already
in the forecast) to our eastern counties. Also went ahead and put
out a SPS for patchy dense fog primarily from Carlisle to Liberty.
Issued at 842 PM EST Wed Jan 9 2013
A few ASOS locations as well as a couple of public reports have
shown that patchy fog has developed across southern and eastern
portions of the CWA. The HRRR actually shows this as well, at least
along the eastern edge of the CWA. Surface analysis shows a
corridor of lower dew point depressions reaching northeastward from
middle Tennessee into eastern Kentucky. Of course we`ve been
concerned with the incoming rain maker, but first, surface high
pressure is still sprawled across the region from the
mid-Mississippi Valley to the Carolinas, keeping winds light. So,
have added patchy fog to the forecast roughly along and southeast of
a Bowling Green-Lexington line. Will let the fog dissipate as rain
moves in and northeast breezes begin to pick up a little later
tonight.
Have also decided to throw in some patchy fog from northern Dubois
County to northern Washington County IN. Dew point depressions are
tightening there and those areas have the added factor of melting
snowcover. A few locations in the Wabash Valley have already
reported some light fog.
In addition, have adjusted the temperatures a bit, especially in the
usual cool spots.
A dense cirrus shield has overspread the region so we have increased
cloud cover to overcast for the rest of the night.
&&
.Short Term (Tonight through Thursday Night)...
Issued at 320 PM EST Wed Jan 9 2013
The weak tail end of a cold front passing mostly over southern
Indiana, northern KY, and locations northeast was located just south
of the Ohio River as of 1945Z. To the southeast of the front, a
thick deck of mid level clouds exists. However, this deck is making
steady progress eastward. Expect skies to go only partly cloudy for
a good portion of this evening before thick, low clouds start to
creep back in from the south after midnight.
After midnight a warm front will approach from the south as part of
a strengthening low pressure system over the OK/TX region. As this
weather system moves northeast to the western Great Lakes by Friday
morning, it will bring us 2 notable rounds of showers/isld storms
late tonight through Friday morning. The first round of elevated
showers/isld storms will come just after midnight tonight and
through tomorrow afternoon as the warm front lifts north through the
area. 6Z/12Z models have been slower with the arrival of these
rains so trended POPs back in time accordingly. We should see a
broad area of light rains slowly move north through the area for
much of Thurs. Any t-storms would likely be elevated north of the
warm front. However, some of the higher res model data suggests a
few scattered cellular structures during the late afternoon/evening
hours Thurs. Still these cells should be of little to no
consequence as morning clouds/rains will rob most areas of heating/
instability. The best chance for any scattered t-storms redeveloping
late Thurs afternoon/evening in the warm sector would be over south
central KY. Total QPF from this first wave of rainfall would be
under a half inch over most locations with areas along and west of
I-65 receiving the most rainfall.
The second wave of rains/isld t-storms will be late Thurs night into
Friday morning with the passage of a cold front. Before then, we
may continue to see scattered rains across the area Thurs evening.
The cold front looks to bring a solid line of rains with embedded
thunder through the area as it will be accompanied by a strong LLJ
(60-70 kts @ h85) and upper level jet support as the potent upper
trough passes just to our northwest. Friday morning would be our
best chance to see some strong to possibly marginally severe storms
due to such a strong LLJ passing through the area. A decent low
level inversion should keep most of the strongest winds aloft.
Still would not be surprise to see 35-50 mph winds mixing down
inside and outside of convection Friday morning. Small hail may
also be possible, but gusty winds and brief heavy rainfall would be
the main threats if any from storms Friday morning.
As far as temps go, they will be tricky over the next 36 hrs as
multiple frontal boundaries push through the area. Lows tonight
will range from the lower 30s over southern Indiana to mid and upper
40s over south central KY as a left over boundary stalls over the
region. Tomorrow expect highs ranging from the upper 40s north to
mid 60s south as we get a warm surge during the afternoon hours.
Thurs night, we`ll likely see a decrease in temps during the evening
hours with lows being reached just after midnight. A warm surge
will occur just ahead of cold front passage Friday morning allowing
temps to warm near dawn. Lows Thurs night should be in the upper
40s to around 60.
.Long Term (Friday through Wednesday)...
Issued at 305 PM EST Wed Jan 9 2013
...Wet and Unsettled Pattern Will Continue...
A building ridge off the Atlantic Coast and a digging western trough
will put the lower half of the Mississippi River Valley and the
entire Ohio River Valley under strong southwest flow aloft. This
will pump in plenty of moisture via an atmospheric river from the
Gulf, and set the stage for a very wet and active long term period.
The cold front associated with our first low pressure system
Thursday night will be entering our western forecast area around
daybreak Friday. Guidance continues to indicate instability will
decrease Thursday night into Friday morning, with some elevated
instability remaining. With the frontal passage at a diurnally
unfavorable time of day, the scenario projected by guidance is
reasonable. So, surfaced-based severe weather is looking less
likely. Surface-based instability will increase a bit through the
day Friday, as high temperatures warm well above normal into the low
and mid 60s. However, shear and large-scale forcing will decrease.
So, will continue with small hail and isolated strong wind gusts
being the main threats.
As this system departs Friday, it will leave behind a stalled
frontal boundary to our northwest that will not move much through
the weekend. Multiple shortwaves will ride over this boundary in
southwest flow aloft, with the first wave of rainfall expected
Saturday afternoon into Sunday. This band of rain should set up
across our northwestern forecast area for the overnight hours. The
rain will diminish a bit Sunday. However, another wave is expected
Sunday afternoon and evening, with yet another wave Sunday night
into Monday. With each wave, the southwest-northeast oriented
rainfall band will slowly track southeast.
Very warm temperatures and near record PWAT for this time
of year will be ushered in from the Gulf, with very high sub-cloud
layer relative humidity and warm cloud depth values in the 10-12Kft
range expected. This sets the stage for high precipitation
efficiency. Area average accumulations of 2-3 inches will be common
from Friday night through the day Monday, with locally higher
amounts possible. With this rain falling on wet ground provided by
the Wednesday and Thursday night/Friday systems, there could be some
areal flooding and rising rivers. Please see the hydrology section
below for more details on river impacts.
The surface front will sag southeast Sunday night, with some cooler
air filtering into our northern forecast area. Probabilistic and
plume data depict a small chance of some mixed precip on the back
side of the system. So, could see some mixed precip late Sunday
night through Monday morning before the system/deep moisture
departs. At this time, do not believe this will cause much of an
impact given the warm ground of late. Will monitor the thermal
profile and deep moisture over the next few model cycles.
As for temperatures, highs Saturday will reach the mid and upper
60s, with a cooling trend expected into Monday as the front slowly
pushes southeast. Highs Monday will range from the mid 30s in the
northwest to around 50 in the southeast. Low temperatures will show
a similar trend, with 40s and 50s Saturday night giving way to 20s
and 30s Monday night.
Guidance differs on the arrival of the next system, but ensemble
data suggests another round of precip Tuesday through Tuesday night.
With the surface boundary projected to be southeast of the forecast
area, cooler air in place across the forecast area, and steady
northeast surface winds, we could see another mixed precip event.
Confidence is not high on the overall thermal profile and placement
of precip, given the differences in model solutions, but ensemble
probabilities suggest a chance of mixed precip. Will continue to
monitor run-to-run model solutions for this system as well. It does
appear the system will exit the area Wednesday, with dry conditions
to follow. High temperatures Tuesday appear to range from mid 30s to
mid 40s, with highs a couple degrees cooler Wednesday. Overnight
lows will trend cooler as well, with generally mid 20s to low 30s
possible by Wednesday night.
&&
.Aviation (06Z TAF Issuance)...
Issued at 1225 AM EST Thu Jan 10 2013
Expect a steady deterioration in ceilings and visibilities from
south to north as a warm front sharpens over Tennessee and lifts
north into Kentucky. The rain shield associated with the front will
lift into BWG over the next couple hours, and into SDF and LEX by
mid-morning.
One complicating factor in LEX is the near-term potential for fog,
as the surface ridge has yet to lose its grip. While visibilities
have really tanked in some of the valley locations, and fog has been
more widespread in east-central Kentucky, believe that there will be
just enough of an easterly wind to close the window on fog there.
Therefore will keep MVFR visibilities until the lower cloud deck
moves in just before daybreak.
Biggest challenge with the rain is just how much conditions will
deteriorate. In general, NAM MOS is much more bullish with IFR
conditions, while GFS MOS barely brings in MVFR. Best chance of IFR
ceilings is in BWG, as we have already seen conditions deteriorate
at BNA and other locations across Tennessee. Will take ceilings down
quickly from 09-12Z, and hold in IFR for much of the day. Diurnal
timing will make it difficult for SDF and LEX to really tank as
advertised by the usually pessimistic NAM. Have generally followed
the timing of the GFS LAMP, but split the difference in conditions
with a few hours of fuel-alternate MVFR.
Warm front will lift north and west of the area, allowing ceilings
to improve and precip to transition to a more intermittent and
showery character late in the day. VFR ceilings in the warm sector
Thursday evening, with just VCSH to handle the precip and SSE winds
kicking up just over 10 kt.
&&
.Hydrology...
A series of winter storms are forecast to move across the Ohio
Valley starting early Thursday morning. The first wave is expected
to deliver up to an inch of rainfall. However, soils are not frozen
and still fairly dry, especially in western Kentucky, so little
runoff is expected.
The more important storm system is expected this weekend when a
series of waves along with copious amounts of moisture will make for
a couple of wet days. Over the entire 3 days, areas should average
between 2 and 3 inches of rain with the heavier amounts over
southern Kentucky. This rain will cause streams to rise and some
near bankfull crests could occur. However, since the rain will be
spread out over several days and current streamflows are not
elevated, any flooding that may occur should be minor. The best
chance for flooding will be in the western portion of the Green
River Basin.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...DENSE FOG ADVISORY UNTIL 8 AM EST THIS MORNING FOR KYZ049-
055>057-066-067.
$$
Update...........13
Short Term.......AMS
Long Term........MJP
Aviation.........RAS
Hydrology........CMC
AREA FORECAST DISCUSSION...corr to initials
NWS LOUISVILLE KY
1105 PM EST WED JAN 09 2013
.Forecast Update...
Issued 1105 PM EST Wed Jan 9 2013
After consulting with JKL, have gone ahead and upgraded to a Dense
Fog Advisory for our eastern edge for the rest of the night.
Issued 1019 PM EST Wed Jan 9 2013
Social media communications and surface obs show that the fog in the
Blue Grass has become thicker and more dense in spots, so have
introduced patchy dense fog (in addition to the patchy fog already
in the forecast) to our eastern counties. Also went ahead and put
out a SPS for patchy dense fog primarily from Carlisle to Liberty.
Issued at 842 PM EST Wed Jan 9 2013
A few ASOS locations as well as a couple of public reports have
shown that patchy fog has developed across southern and eastern
portions of the CWA. The HRRR actually shows this as well, at least
along the eastern edge of the CWA. Surface analysis shows a
corridor of lower dew point depressions reaching northeastward from
middle Tennessee into eastern Kentucky. Of course we`ve been
concerned with the incoming rain maker, but first, surface high
pressure is still sprawled across the region from the
mid-Mississippi Valley to the Carolinas, keeping winds light. So,
have added patchy fog to the forecast roughly along and southeast of
a Bowling Green-Lexington line. Will let the fog dissipate as rain
moves in and northeast breezes begin to pick up a little later
tonight.
Have also decided to throw in some patchy fog from northern Dubois
County to northern Washington County IN. Dew point depressions are
tightening there and those areas have the added factor of melting
snowcover. A few locations in the Wabash Valley have already
reported some light fog.
In addition, have adjusted the temperatures a bit, especially in the
usual cool spots.
A dense cirrus shield has overspread the region so we have increased
cloud cover to overcast for the rest of the night.
&&
.Short Term (Tonight through Thursday Night)...
Issued at 320 PM EST Wed Jan 9 2013
The weak tail end of a cold front passing mostly over southern
Indiana, northern KY, and locations northeast was located just south
of the Ohio River as of 1945Z. To the southeast of the front, a
thick deck of mid level clouds exists. However, this deck is making
steady progress eastward. Expect skies to go only partly cloudy for
a good portion of this evening before thick, low clouds start to
creep back in from the south after midnight.
After midnight a warm front will approach from the south as part of
a strengthening low pressure system over the OK/TX region. As this
weather system moves northeast to the western Great Lakes by Friday
morning, it will bring us 2 notable rounds of showers/isld storms
late tonight through Friday morning. The first round of elevated
showers/isld storms will come just after midnight tonight and
through tomorrow afternoon as the warm front lifts north through the
area. 6Z/12Z models have been slower with the arrival of these
rains so trended POPs back in time accordingly. We should see a
broad area of light rains slowly move north through the area for
much of Thurs. Any t-storms would likely be elevated north of the
warm front. However, some of the higher res model data suggests a
few scattered cellular structures during the late afternoon/evening
hours Thurs. Still these cells should be of little to no
consequence as morning clouds/rains will rob most areas of heating/
instability. The best chance for any scattered t-storms redeveloping
late Thurs afternoon/evening in the warm sector would be over south
central KY. Total QPF from this first wave of rainfall would be
under a half inch over most locations with areas along and west of
I-65 receiving the most rainfall.
The second wave of rains/isld t-storms will be late Thurs night into
Friday morning with the passage of a cold front. Before then, we
may continue to see scattered rains across the area Thurs evening.
The cold front looks to bring a solid line of rains with embedded
thunder through the area as it will be accompanied by a strong LLJ
(60-70 kts @ h85) and upper level jet support as the potent upper
trough passes just to our northwest. Friday morning would be our
best chance to see some strong to possibly marginally severe storms
due to such a strong LLJ passing through the area. A decent low
level inversion should keep most of the strongest winds aloft.
Still would not be surprise to see 35-50 mph winds mixing down
inside and outside of convection Friday morning. Small hail may
also be possible, but gusty winds and brief heavy rainfall would be
the main threats if any from storms Friday morning.
As far as temps go, they will be tricky over the next 36 hrs as
multiple frontal boundaries push through the area. Lows tonight
will range from the lower 30s over southern Indiana to mid and upper
40s over south central KY as a left over boundary stalls over the
region. Tomorrow expect highs ranging from the upper 40s north to
mid 60s south as we get a warm surge during the afternoon hours.
Thurs night, we`ll likely see a decrease in temps during the evening
hours with lows being reached just after midnight. A warm surge
will occur just ahead of cold front passage Friday morning allowing
temps to warm near dawn. Lows Thurs night should be in the upper
40s to around 60.
.Long Term (Friday through Wednesday)...
Issued at 305 PM EST Wed Jan 9 2013
...Wet and Unsettled Pattern Will Continue...
A building ridge off the Atlantic Coast and a digging western trough
will put the lower half of the Mississippi River Valley and the
entire Ohio River Valley under strong southwest flow aloft. This
will pump in plenty of moisture via an atmospheric river from the
Gulf, and set the stage for a very wet and active long term period.
The cold front associated with our first low pressure system
Thursday night will be entering our western forecast area around
daybreak Friday. Guidance continues to indicate instability will
decrease Thursday night into Friday morning, with some elevated
instability remaining. With the frontal passage at a diurnally
unfavorable time of day, the scenario projected by guidance is
reasonable. So, surfaced-based severe weather is looking less
likely. Surface-based instability will increase a bit through the
day Friday, as high temperatures warm well above normal into the low
and mid 60s. However, shear and large-scale forcing will decrease.
So, will continue with small hail and isolated strong wind gusts
being the main threats.
As this system departs Friday, it will leave behind a stalled
frontal boundary to our northwest that will not move much through
the weekend. Multiple shortwaves will ride over this boundary in
southwest flow aloft, with the first wave of rainfall expected
Saturday afternoon into Sunday. This band of rain should set up
across our northwestern forecast area for the overnight hours. The
rain will diminish a bit Sunday. However, another wave is expected
Sunday afternoon and evening, with yet another wave Sunday night
into Monday. With each wave, the southwest-northeast oriented
rainfall band will slowly track southeast.
Very warm temperatures and near record PWAT for this time
of year will be ushered in from the Gulf, with very high sub-cloud
layer relative humidity and warm cloud depth values in the 10-12Kft
range expected. This sets the stage for high precipitation
efficiency. Area average accumulations of 2-3 inches will be common
from Friday night through the day Monday, with locally higher
amounts possible. With this rain falling on wet ground provided by
the Wednesday and Thursday night/Friday systems, there could be some
areal flooding and rising rivers. Please see the hydrology section
below for more details on river impacts.
The surface front will sag southeast Sunday night, with some cooler
air filtering into our northern forecast area. Probabilistic and
plume data depict a small chance of some mixed precip on the back
side of the system. So, could see some mixed precip late Sunday
night through Monday morning before the system/deep moisture
departs. At this time, do not believe this will cause much of an
impact given the warm ground of late. Will monitor the thermal
profile and deep moisture over the next few model cycles.
As for temperatures, highs Saturday will reach the mid and upper
60s, with a cooling trend expected into Monday as the front slowly
pushes southeast. Highs Monday will range from the mid 30s in the
northwest to around 50 in the southeast. Low temperatures will show
a similar trend, with 40s and 50s Saturday night giving way to 20s
and 30s Monday night.
Guidance differs on the arrival of the next system, but ensemble
data suggests another round of precip Tuesday through Tuesday night.
With the surface boundary projected to be southeast of the forecast
area, cooler air in place across the forecast area, and steady
northeast surface winds, we could see another mixed precip event.
Confidence is not high on the overall thermal profile and placement
of precip, given the differences in model solutions, but ensemble
probabilities suggest a chance of mixed precip. Will continue to
monitor run-to-run model solutions for this system as well. It does
appear the system will exit the area Wednesday, with dry conditions
to follow. High temperatures Tuesday appear to range from mid 30s to
mid 40s, with highs a couple degrees cooler Wednesday. Overnight
lows will trend cooler as well, with generally mid 20s to low 30s
possible by Wednesday night.
&&
.Aviation (00Z TAF Issuance)...
Issued at 630 PM EST Wed Jan 9 2013
Flying conditions will deteriorate significantly during this TAF
period. A weakening upper level disturbance moving from Texas to
Missouri will pull a large area of rain northeastward along with
it. Rain will move into the BWG area after midnight tonight and
make it to the northern TAF sites by morning. The rain will then
continue through midday with low ceilings and MVFR visibilities
(possibly IFR at BWG).
During the afternoon hours a warm front will pass from south to
north across Kentucky, which will allow the rain to become more
scattered and will allow ceilings to rise a bit, though probably
stay MVFR.
Winds will gradually shift from northeast tonight to the east
tomorrow morning and to the southeast tomorrow afternoon as the warm
front approaches and passes on through.
&&
.Hydrology...
A series of winter storms are forecast to move across the Ohio
Valley starting early Thursday morning. The first wave is expected
to deliver up to an inch of rainfall. However, soils are not frozen
and still fairly dry, especially in western Kentucky, so little
runoff is expected.
The more important storm system is expected this weekend when a
series of waves along with copious amounts of moisture will make for
a couple of wet days. Over the entire 3 days, areas should average
between 2 and 3 inches of rain with the heavier amounts over
southern Kentucky. This rain will cause streams to rise and some
near bankfull crests could occur. However, since the rain will be
spread out over several days and current streamflows are not
elevated, any flooding that may occur should be minor. The best
chance for flooding will be in the western portion of the Green
River Basin.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...DENSE FOG ADVISORY UNTIL 8 AM EST THURSDAY FOR KYZ049-055>057-
066-067.
$$
Update...........13
Short Term.......AMS
Long Term........MJP
Aviation.........13
Hydrology........CMC
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
927 PM MST WED JAN 9 2013
.SHORT TERM...VALID FOR THU AND FRI...
WINDS AT THE LIVINGSTON WIND DOT SITE WERE MEETING ADVISORY
CRITERIA SINCE JUST AFTER 02Z. MSAS SHOWED A SURFACE LOW NW OF
HARLOWTON WHICH WAS ENHANCING THE PRESSURE GRADIENT LOCALLY OVER
THE KLVM AREA. THE RAP PICKED UP ON THE SURFACE LOW AND MOVED IT
SE OVER THE NEXT FEW HOURS...SO WOULD EXPECT THE WINDS TO DECREASE
IN THE KLVM AREA.
GIVEN 03Z TEMPERATURES IN THE 40S OVER MOST OF THE AREA AND
EXTENSIVE CLOUD COVER STREAMING OVER THE AREA ON IR IMAGERY...HAVE
RAISED OVERNIGHT LOWS.
NEW WRF CAME IN WITH SOME CHANGES FROM IT/S PREVIOUS RUN...WHILE
NEW GFS WAS LOOKING SIMILAR TO IT/S PREVIOUS RUN. NEW WRF WAS SLOWER
WITH EASTWARD MOVEMENT OF UPPER LOW THU NIGHT AND STILL BROUGHT COLD
FRONT THROUGH THE AREA LATE THU AFTERNOON THROUGH THU EVENING. NEW
RUN WAS SLOWER WITH COLDER AIR ASSOCIATED WITH THE LOW AS WELL.
PRECIPITATION WAS SLOW TO MOVE INTO THE AREA ON BOTH MODELS...AND
THE POPS OVER THE WESTERN ZONES MAY BE A BIT OVERDONE THU MORNING.
WILL LET NEXT SHIFT EVALUATE THIS MORE CLOSELY. ALSO NEW WRF KEPT
THE PRECIPITATION BULLSEYE...THAT WAS OVER THE SE ZONES...SE OF
THE AREA FRI AFTERNOON. OTHERWISE WRF QPF AMOUNTS OVER THE
FORECAST AREA WERE SIMILAR TO THE PREVIOUS RUN. NOTED NEW MET
GUIDANCE LOWERED SNOW AMOUNTS THU NIGHT AND RAISED THEM FOR
FRI/FRI NIGHT...LIKELY DUE TO SLOWER SYSTEM MOVEMENT. WRF
CONTINUED TO SHOW HIGHER QPF AMOUNTS THAN GFS. GFS STILL SHOWED
LATE THU NIGHT THROUGH FRI AS BEST TIME FOR ACCUMULATING SNOW FROM
KBIL W. SO...SOME CHANGES MAY BE NEEDED TO SLOW PRECIPITATION
TIMING FOR THU. NO STRONG REASONS SEEN TO CHANGE ANY SNOW
AMOUNTS.
GIVEN THE HIGHER TEMPERATURES EXPECTED TONIGHT AND THE SLOWER
ADVANCEMENT OF THE PRECIPITATION...HAVE RAISED HIGHS ON THU.
ARTHUR
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
THE EXTENDED FORECAST PERIOD BEGINS SATURDAY NIGHT...AS THE LAST
REMNANTS OF THE APPROACHING WINTER STORM SYSTEM IS EXITING THE
REGION TO THE EAST. LITTLE ADDITIONAL ACCUMULATIONS ARE
ANTICIPATED AT THIS TIME. FOLLOWING THIS SYSTEM IT APPEARS
NORTHWEST FLOW ALOFT WILL REMAIN IN CONTROL ACROSS THE
REGION...AND COMBINED WITH EXTENSIVE SNOW COVER...EXPECT
TEMPERATURES TO REMAIN ON THE COOL SIDE. HIGHS WILL ONLY CLIMB TO
TEENS AND LOW 20S BY MONDAY...AND BACK ABOVE FREEZING IN SOME
AREAS WEDNESDAY. THIS IS WELL BELOW CURRENT GUIDANCE...BUT CANNOT
SEE MUCH WARMER TEMPERATURE BECOMING REALITY WITH THE SNOW COVER
EXPECTED...AND POTENTIAL FOR SEVERAL REINFORCING WAVES OF COLD AIR
AND PRECIP ACROSS THE REGION THROUGH THE BEGINNING OF THE WORK
WEEK.
AS MENTIONED...TIMING REMAINS UNCERTAIN WITH REGARD TO REINFORCING
WAVES INTO THE REGION...SO HAVE CONTINUED WITH INHERITED SLIGHT
CHANCE TO CHANCE POPS THROUGH THE REMAINDER OF THE PERIOD.
INDICATIONS AT THIS TIME ARE FOR WAVES THROUGH THE REGION LATE
MONDAY AND LATE TUESDAY AT THIS TIME.
ALSO OF INTEREST IS A RETURN OF INCREASED WIND ACROSS THE WESTERN
AREAS...MAINLY WEST OF KBIL...INCLUDING KLVM BY SUNDAY NIGHT. ALTHOUGH
WINDS ARE NOT EXPECTED TO APPROACH SEVERE CRITERIA...BLOWING SNOW
WILL BE POSSIBLE. HAVE INCLUDED BLOWING SNOW ACROSS THOSE WESTERN
AREAS SUNDAY NIGHT THROUGH MONDAY NIGHT. WINDS WILL REMAIN BREEZY
THROUGH THE REMAINDER EXPECT WINDS TO TAPER OFF TUESDAY
NIGHT...AND SNOW TO BE CRUSTING OVER BY TUESDAY. AAG
&&
.AVIATION...
STRONG SOUTHWEST WINDS WILL BE LIKELY IN THE KLVM AREA AND ALONG
FAVORED LOCATIONS OVER THE FOOTHILLS UNTIL 0900UTC. OTHERWISE
EXPECT INCREASING CLOUDS AND LOWERING CEILINGS DURING THE DAY ON
THURSDAY OVER WESTERN AREAS IN THE MORNING SHIFTING EAST BY
AFTERNOON. SNOWFALL WILL BECOME WIDESPREAD FROM WEST TO EAST FROM
THURSDAY AFTERNOON INTO FRIDAY EVENING. BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
THU FRI SAT SUN MON TUE WED
-----------------------------------------------------------
BIL 034/038 007/008 903/013 002/018 001/020 013/027 020/034
07/O ++/S 61/B 11/B 11/N 32/S 22/J
LVM 032/034 002/010 906/012 901/016 000/016 008/025 013/028
2+/O +9/S 51/B 11/B 22/J 32/S 22/J
HDN 030/037 008/009 904/013 903/017 003/019 011/026 018/032
06/S ++/S 62/S 11/B 11/B 33/S 22/J
MLS 025/035 005/007 908/008 906/013 902/016 007/022 015/029
04/S ++/S 83/S 11/B 11/E 23/S 22/J
4BQ 026/038 008/009 905/010 904/016 902/017 007/022 015/030
03/S ++/S 93/S 11/B 11/E 23/S 22/J
BHK 021/036 003/005 908/004 905/012 903/013 002/018 011/027
03/S ++/S 93/S 11/B 11/E 23/S 22/J
SHR 029/039 006/009 903/011 904/018 901/018 009/025 017/033
03/O ++/S 72/S 11/B 11/B 23/S 32/J
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WARNING IN EFFECT FROM NOON THURSDAY TO 6 AM MST
SATURDAY FOR ZONES 28-29-34-35-38>42-56-57-63>68.
WINTER STORM WATCH IN EFFECT FROM THURSDAY EVENING THROUGH
SATURDAY AFTERNOON FOR ZONES 30>33-36-37-58.
WY...WINTER STORM WATCH IN EFFECT FROM THURSDAY EVENING THROUGH
SATURDAY AFTERNOON FOR ZONES 98-99.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1151 PM CST WED JAN 9 2013
.UPDATE...FOR 06Z TAFS
&&
.AVIATION...
A WARM FRONT WELL SOUTH OF THE REGION AT 06Z WILL STENGTHEN AND
MOVE NORTH DURING THIS PERIOD AS LOW PRESSURE MOVES FROM TX TOWARD
MID MS VALLEY. LOW CLOUDS AND SOME FOG EXPECTED AT ALL 3 TAF SITES
FOR REST OF TONIGHT AND MUCH OF THURSDAY. IN ADDITION...AREAS OF
LIGHT TO MODERATE RAIN WILL IMPACT MAINLY KBNA AND KCKV THE REST
OF TONIGHT AND INTO EARLY THURSDAY AHEAD OF THE WARM FRONT. WINDS
WILL INCREASE AND BECOME GUSTY THURSDAY AFTERNOON/NIGHT AS
SIGNIFICANT SFC PRESSURE FALLS OCCUR TO OUR NORTHWEST.
&&
.PREV DISCUSSION... /ISSUED 1006 PM CST WED JAN 9 2013/
UPDATE...CURRENT FORECAST FOR MIDDLE TENNESSEE IS HOLDING UP WELL
FOR THE MOST PART. RAIN CONTINUES TO PROPAGATE NORTHWARD WHILE
WEAKENING. LATEST HRRR SHOWS MAINLY LIGHT PRECIPITATION CONTINUING
OVERNIGHT. GIVEN THE CURRENT RADAR TREND, WILL UPDATE THE FORECAST
SHORTLY TO REMOVE THE SLIGHT CHANCE OF THUNDER WE HAVE RUNNING IN
THE OVERNIGHT PERIOD. BUT NO OTHER CHANGES ARE PLANNED AT THIS
TIME.
PREV DISCUSSION... /ISSUED 614 PM CST WED JAN 9 2013/
UPDATE...FOR 00Z AVIATION FORECAST
AVIATION...
THIS 24 HOUR PERIOD WILL BE DOMINATED BY PLENTY OF MOISTURE THANKS
TO STRONG H5 LOW REMAINING WELL TO OUR WEST. THE LOW HAS BEEN OVER
THE TX BIG BEND LATELY BUT SHOULD START MOVING NORTHEAST TOWARD
OKLAHOMA OVERNIGHT AND THURSDAY.
EXTENSIVE CLOUDS WILL CONTINUE ACROSS THE REGION THROUGH AT LEAST
00Z FRIDAY...WITH WIDESPREAD MVRF/IFR CONDITIONS AND POCKETS OF
LIFR. VSBYS WILL FREQUENTLY BE 4SM OR LESS IN FOG AND LIGHT
RAIN...ESPECIALLY LATE TONIGHT THROUGH MID MORNING THURSDAY.
EXPECT AREAS OF RAIN TO DRIFT NORTHWARD OVERNIGHT AND THURSDAY
MORNING...WITH SCATTERED TO NUMEROUS SHOWERS DEVELOPING THURSDAY
AFTERNOON.
LIGHT NORTHEAST SFC WINDS THIS EVENING WILL GRADUALLY BECOME MORE
EASTERLY OVERNIGHT AS SFC HIGH PRESSURE MOVES EASTWARD ACROSS THE
OH VALLEY...ALLOWING WARM FRONT TO MOVE NORTHWARD. BY THURSDAY
AFTERNOON...THE WARM FRONT WILL MOVE NORTH OF MIDDLE TN AND WINDS
WILL BECOME MORE SOUTHEASTERLY/GUSTY IN RESPONSE TO FALLING
PRESSURES ACROSS THE MIDWEST U.S.
PREV DISCUSSION... /ISSUED 517 PM CST WED JAN 9 2013/
UPDATE...ALREADY GETTING SEVERAL REPORTS OF FOG FROM AROUND THE
AREA VIA TWITTER AND NWSCHAT. GIVEN THAT THE AIR IS ALREADY
MOIST, AND WON`T GET ANY LESS MOIST, BELIEVE FOG MAY BECOME MORE
OF A PROBLEM DEEPER INTO THE EVENING. WINDS WILL PICK UP AFTER
MIDNIGHT, SO THE FOG SHOULD BECOME LESS PERVASIVE THEN.
PREV DISCUSSION... /ISSUED 322 PM CST WED JAN 9 2013/
DISCUSSION...
BUSY FORECAST OVER THE NEXT WEEK WITH RAIN CHANCES NEARLY EVERY
PERIOD...NEAR RECORD HIGH TEMPERATURES...HEAVY RAINFALL AND
POSSIBLE FLOOD IMPACTS...AND POTENTIAL FOR EVEN SOME WINTER
WEATHER EARLY NEXT WEEK.
RADAR THIS AFTERNOON SHOWS RAIN HAS MOSTLY DIMINISHED ACROSS THE
CWA EXCEPT OVER THE FAR SOUTH AND SOUTHEAST. HOWEVER...RAIN
CONTINUES TO DEVELOP ACROSS NORTHERN MS/AL TO THE NORTH OF A WARM
FRONT LOCATED ACROSS CENTRAL MS/AL. AS THE FRONT LIFTS NORTHWARD
TONIGHT...SHOWERS AND EVEN A FEW THUNDERSTORMS WILL CONTINUE TO
DEVELOP ALONG AND NORTH OF THE BOUNDARY AND SPREAD ACROSS THE MID
STATE. BEST RAIN CHANCES WILL BE IN WESTERN HALF OF FORECAST AREA
WHERE VERTICAL MOTION WILL BE STRONGER...AND CATEGORICAL POPS
APPEAR WARRANTED AFTER MIDNIGHT. MUCH WARMER TEMPERATURES ARE ALSO
ANTICIPATED TONIGHT DUE TO THE CONTINUED WAA WITH LOWS IN THE
UPPER 40S AND 50S.
SHOWERS AND STORMS WILL TEND TO DIMINISH FROM SOUTH TO NORTH DURING
THE DAY ON THURSDAY AS ACTIVITY FOCUSES MORE TO THE WEST CLOSER TO
UPPER LEVEL LOW TRACK. HOWEVER...CONVECTION WILL SPREAD BACK EAST
INTO THE MID STATE THURSDAY NIGHT AS WEAKENING UPPER LOW PASSES
OFF TO OUR NORTH...WITH HIGHEST POPS IN OUR NORTHWEST ZONES.
STRONG DEEP LAYER SHEAR AND VERY WEAK INSTABILITY COULD PROMPT A
FEW STRONG STORMS OVER OUR WEST AND NORTHWEST THURSDAY NIGHT...BUT
NO SEVERE WEATHER IS EXPECTED AT THIS TIME. PRECIP WILL DIMINISH
FROM WEST TO EAST ON FRIDAY...WITH PARTLY CLOUDY SKIES POSSIBLE BY
AFTERNOON. THIS WILL ALLOW FOR POTENTIAL RECORD HIGH TEMPERATURES
WITH HIGHS IN THE UPPER 60S AND LOW 70S. RECORDS FOR FRIDAY ARE 72
DEGREES AT NASHVILLE IN 1890...AND 64 DEGREES AT CROSSVILLE IN
1960...AND CURRENT FORECAST TIES OR BEATS THE RECORDS AT BOTH
LOCATIONS.
A HIGHER IMPACT EVENT IS FORECAST TO BEGIN ON SATURDAY AND
CONTINUE THROUGH WEDNESDAY OF NEXT WEEK AS A LARGE AND POWERFUL
UPPER TROUGH DIGS ACROSS THE WESTERN CONUS...WITH SEVERAL
SHORTWAVES IN THE SOUTHWESTERLY FLOW ALOFT OVER THE EASTERN PART
OF THE COUNTRY BRINGING US NUMEROUS ROUNDS OF RAIN AND SOME
THUNDERSTORMS. INITIAL SHORTWAVE TROUGH WILL CROSS THE REGION LATE
SATURDAY INTO SATURDAY NIGHT...FORCING A COLD FRONT SOUTHEAST INTO
THE MID STATE ON SUNDAY. ALL MODEL GUIDANCE INDICATES AN AXIS OF
HEAVY RAINFALL WILL SET UP ALONG THE BOUNDARY AS STRONG MOISTURE
TRANSPORT FROM THE GULF OF MEXICO WITH PWATS AS HIGH AS 1.75
INCHES INTERACTS WITH THE FRONT. SUCH A STRONG POSITIVE MOISTURE
ANOMALY...NEARLY ONE QUARTER INCH OVER THE CLIMATOLOGICAL MAXIMUM
PWAT FOR JANUARY...COMBINED WITH FRONTAL BOUNDARY FOCUS RAISES
EYEBROWS ON HEAVY RAINFALL POSSIBILITY AND POTENTIAL FOR FLOODING.
HOWEVER...REMAINS DIFFICULT TO DISCERN AT THIS EXTENDED FORECAST
RANGE EXACTLY WHERE FRONT WILL END UP...AND WHERE ANY POSSIBLE
FLOOD IMPACTS WOULD OCCUR. FOR NOW WILL JUST SHOW LIKELY TO
CATEGORICAL POPS IN THE SATURDAY THROUGH MONDAY TIME
FRAME...CHANCE TO LIKELY POPS TUESDAY INTO WEDNESDAY BEFORE PRECIP
ENDS...AND REISSUE ESF TO HIGHLIGHT HEAVY RAINFALL AND FLOOD
POTENTIAL. CURRENTLY APPEARS THAT SOME PORTION OF THE MID STATE
COULD RECEIVE SEVERAL INCHES OF RAIN DURING THIS TIME PERIOD.
IN ADDITION...12Z GFS/ECMWF RUNS SUGGEST FRONT WILL MOVE FAR
ENOUGH SOUTHEAST TO ALLOW FOR SIGNIFICANT CAA OVER FAR NORTHWEST
ZONES...WITH TEMPERATURES COLD ENOUGH FOR POSSIBLE WINTER
PRECIPITATION. FORECAST SOUNDINGS SUGGEST MARGINAL CONDITIONS FOR
FREEZING RAIN OR SLEET BOTH MONDAY AND TUESDAY MORNINGS...BUT THIS
IS HIGHLY UNCERTAIN AT THIS RANGE AND VERY DEPENDENT ON FRONTAL
POSITION AND TEMPERATURES. FOR NOW WILL LEAVE FORECAST AS ALL
RAIN DUE TO THE UNCERTAINTY AND KEPT TEMPERATURES NEAR MEX MOS
VALUES.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
49
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1006 PM CST WED JAN 9 2013
.UPDATE...CURRENT FORECAST FOR MIDDLE TENNESSEE IS HOLDING UP WELL
FOR THE MOST PART. RAIN CONTINUES TO PROPAGATE NORTHWARD WHILE
WEAKENING. LATEST HRRR SHOWS MAINLY LIGHT PRECIPITATION CONTINUING
OVERNIGHT. GIVEN THE CURRENT RADAR TREND, WILL UPDATE THE FORECAST
SHORTLY TO REMOVE THE SLIGHT CHANCE OF THUNDER WE HAVE RUNNING IN
THE OVERNIGHT PERIOD. BUT NO OTHER CHANGES ARE PLANNED AT THIS
TIME.
&&
.PREV DISCUSSION... /ISSUED 614 PM CST WED JAN 9 2013/
UPDATE...FOR 00Z AVIATION FORECAST
AVIATION...
THIS 24 HOUR PERIOD WILL BE DOMINATED BY PLENTY OF MOISTURE THANKS
TO STRONG H5 LOW REMAINING WELL TO OUR WEST. THE LOW HAS BEEN OVER
THE TX BIG BEND LATELY BUT SHOULD START MOVING NORTHEAST TOWARD
OKLAHOMA OVERNIGHT AND THURSDAY.
EXTENSIVE CLOUDS WILL CONTINUE ACROSS THE REGION THROUGH AT LEAST
00Z FRIDAY...WITH WIDESPREAD MVRF/IFR CONDITIONS AND POCKETS OF
LIFR. VSBYS WILL FREQUENTLY BE 4SM OR LESS IN FOG AND LIGHT
RAIN...ESPECIALLY LATE TONIGHT THROUGH MID MORNING THURSDAY.
EXPECT AREAS OF RAIN TO DRIFT NORTHWARD OVERNIGHT AND THURSDAY
MORNING...WITH SCATTERED TO NUMEROUS SHOWERS DEVELOPING THURSDAY
AFTERNOON.
LIGHT NORTHEAST SFC WINDS THIS EVENING WILL GRADUALLY BECOME MORE
EASTERLY OVERNIGHT AS SFC HIGH PRESSURE MOVES EASTWARD ACROSS THE
OH VALLEY...ALLOWING WARM FRONT TO MOVE NORTHWARD. BY THURSDAY
AFTERNOON...THE WARM FRONT WILL MOVE NORTH OF MIDDLE TN AND WINDS
WILL BECOME MORE SOUTHEASTERLY/GUSTY IN RESPONSE TO FALLING
PRESSURES ACROSS THE MIDWEST U.S.
PREV DISCUSSION... /ISSUED 517 PM CST WED JAN 9 2013/
UPDATE...ALREADY GETTING SEVERAL REPORTS OF FOG FROM AROUND THE
AREA VIA TWITTER AND NWSCHAT. GIVEN THAT THE AIR IS ALREADY
MOIST, AND WON`T GET ANY LESS MOIST, BELIEVE FOG MAY BECOME MORE
OF A PROBLEM DEEPER INTO THE EVENING. WINDS WILL PICK UP AFTER
MIDNIGHT, SO THE FOG SHOULD BECOME LESS PERVASIVE THEN.
PREV DISCUSSION... /ISSUED 322 PM CST WED JAN 9 2013/
DISCUSSION...
BUSY FORECAST OVER THE NEXT WEEK WITH RAIN CHANCES NEARLY EVERY
PERIOD...NEAR RECORD HIGH TEMPERATURES...HEAVY RAINFALL AND
POSSIBLE FLOOD IMPACTS...AND POTENTIAL FOR EVEN SOME WINTER
WEATHER EARLY NEXT WEEK.
RADAR THIS AFTERNOON SHOWS RAIN HAS MOSTLY DIMINISHED ACROSS THE
CWA EXCEPT OVER THE FAR SOUTH AND SOUTHEAST. HOWEVER...RAIN
CONTINUES TO DEVELOP ACROSS NORTHERN MS/AL TO THE NORTH OF A WARM
FRONT LOCATED ACROSS CENTRAL MS/AL. AS THE FRONT LIFTS NORTHWARD
TONIGHT...SHOWERS AND EVEN A FEW THUNDERSTORMS WILL CONTINUE TO
DEVELOP ALONG AND NORTH OF THE BOUNDARY AND SPREAD ACROSS THE MID
STATE. BEST RAIN CHANCES WILL BE IN WESTERN HALF OF FORECAST AREA
WHERE VERTICAL MOTION WILL BE STRONGER...AND CATEGORICAL POPS
APPEAR WARRANTED AFTER MIDNIGHT. MUCH WARMER TEMPERATURES ARE ALSO
ANTICIPATED TONIGHT DUE TO THE CONTINUED WAA WITH LOWS IN THE
UPPER 40S AND 50S.
SHOWERS AND STORMS WILL TEND TO DIMINISH FROM SOUTH TO NORTH DURING
THE DAY ON THURSDAY AS ACTIVITY FOCUSES MORE TO THE WEST CLOSER TO
UPPER LEVEL LOW TRACK. HOWEVER...CONVECTION WILL SPREAD BACK EAST
INTO THE MID STATE THURSDAY NIGHT AS WEAKENING UPPER LOW PASSES
OFF TO OUR NORTH...WITH HIGHEST POPS IN OUR NORTHWEST ZONES.
STRONG DEEP LAYER SHEAR AND VERY WEAK INSTABILITY COULD PROMPT A
FEW STRONG STORMS OVER OUR WEST AND NORTHWEST THURSDAY NIGHT...BUT
NO SEVERE WEATHER IS EXPECTED AT THIS TIME. PRECIP WILL DIMINISH
FROM WEST TO EAST ON FRIDAY...WITH PARTLY CLOUDY SKIES POSSIBLE BY
AFTERNOON. THIS WILL ALLOW FOR POTENTIAL RECORD HIGH TEMPERATURES
WITH HIGHS IN THE UPPER 60S AND LOW 70S. RECORDS FOR FRIDAY ARE 72
DEGREES AT NASHVILLE IN 1890...AND 64 DEGREES AT CROSSVILLE IN
1960...AND CURRENT FORECAST TIES OR BEATS THE RECORDS AT BOTH
LOCATIONS.
A HIGHER IMPACT EVENT IS FORECAST TO BEGIN ON SATURDAY AND
CONTINUE THROUGH WEDNESDAY OF NEXT WEEK AS A LARGE AND POWERFUL
UPPER TROUGH DIGS ACROSS THE WESTERN CONUS...WITH SEVERAL
SHORTWAVES IN THE SOUTHWESTERLY FLOW ALOFT OVER THE EASTERN PART
OF THE COUNTRY BRINGING US NUMEROUS ROUNDS OF RAIN AND SOME
THUNDERSTORMS. INITIAL SHORTWAVE TROUGH WILL CROSS THE REGION LATE
SATURDAY INTO SATURDAY NIGHT...FORCING A COLD FRONT SOUTHEAST INTO
THE MID STATE ON SUNDAY. ALL MODEL GUIDANCE INDICATES AN AXIS OF
HEAVY RAINFALL WILL SET UP ALONG THE BOUNDARY AS STRONG MOISTURE
TRANSPORT FROM THE GULF OF MEXICO WITH PWATS AS HIGH AS 1.75
INCHES INTERACTS WITH THE FRONT. SUCH A STRONG POSITIVE MOISTURE
ANOMALY...NEARLY ONE QUARTER INCH OVER THE CLIMATOLOGICAL MAXIMUM
PWAT FOR JANUARY...COMBINED WITH FRONTAL BOUNDARY FOCUS RAISES
EYEBROWS ON HEAVY RAINFALL POSSIBILITY AND POTENTIAL FOR FLOODING.
HOWEVER...REMAINS DIFFICULT TO DISCERN AT THIS EXTENDED FORECAST
RANGE EXACTLY WHERE FRONT WILL END UP...AND WHERE ANY POSSIBLE
FLOOD IMPACTS WOULD OCCUR. FOR NOW WILL JUST SHOW LIKELY TO
CATEGORICAL POPS IN THE SATURDAY THROUGH MONDAY TIME
FRAME...CHANCE TO LIKELY POPS TUESDAY INTO WEDNESDAY BEFORE PRECIP
ENDS...AND REISSUE ESF TO HIGHLIGHT HEAVY RAINFALL AND FLOOD
POTENTIAL. CURRENTLY APPEARS THAT SOME PORTION OF THE MID STATE
COULD RECEIVE SEVERAL INCHES OF RAIN DURING THIS TIME PERIOD.
IN ADDITION...12Z GFS/ECMWF RUNS SUGGEST FRONT WILL MOVE FAR
ENOUGH SOUTHEAST TO ALLOW FOR SIGNIFICANT CAA OVER FAR NORTHWEST
ZONES...WITH TEMPERATURES COLD ENOUGH FOR POSSIBLE WINTER
PRECIPITATION. FORECAST SOUNDINGS SUGGEST MARGINAL CONDITIONS FOR
FREEZING RAIN OR SLEET BOTH MONDAY AND TUESDAY MORNINGS...BUT THIS
IS HIGHLY UNCERTAIN AT THIS RANGE AND VERY DEPENDENT ON FRONTAL
POSITION AND TEMPERATURES. FOR NOW WILL LEAVE FORECAST AS ALL
RAIN DUE TO THE UNCERTAINTY AND KEPT TEMPERATURES NEAR MEX MOS
VALUES.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
ROSE
FORECAST DISCREPANCIES STILL SHOW UP FOR SATURDAY WITH NAM AND GFS
MODELS BRINGING A WET INSIDE SLIDER OVER THE BAY AREA SATURDAY
AFTERNOON BRINGING A ROUND OF COLD RAIN SHOWERS. THE ECMWF IS DRY
AND REMAINS THE MODEL OF CHOICE...SO FORECAST REMAINS DRY. GFS AND
PREVIOUS NAM RUNS QUICKLY BRING ANOTHER SYSTEM BY 12Z SUNDAY THAT
THE ECMWF DOESN`T SHOW. WILL NEED TO MONITOR TRENDS TO COVER
WEEKEND FORECAST PROPERLY ONCE WE GET THROUGH THIS INITIAL SHOT OF
COLD AND UNSETTLED AIR. EXPECTED LONGWAVE PATTERN SUPPORTS THE
DRIER ECMWF SOLUTION. HIGHER CONFIDENCE FOR DRYING AND WARMING
TREND SUNDAY INTO EARLY NEXT WEEK AS HIGH PRESSURE BUILDS.
&&
.AVIATION...AS OF 3:45 AM PST THURSDAY...CHALLENGIG FORECAST TODAY
WITH SCATTERED SHOWERS IMPACTING A TERMINAL ONE HOUR FOLLOWED BY
FEW/SCT SKIES FOR ANOTHER HOUR. TAFS MOSTLY HAVE VCSH WITH BKN/OVC
BY LATER THIS MORNING SWITCHING BACK TO FEW/SKC AFTER 03Z THIS
EVENING. LOW TO MODERATE CONFIDENCE.
VICINITY OF KSFO...LOOK FOR VFR THROUGH THE DAY ALONG WITH
POSSIBLE SHOWERS THROUGH 03Z THIS EVENING. WESTERLY WINDS COULD
GUST UP TO 20 KT THROUGH THE DAY. MODERATE CONFIDENCE.
KSFO BRIDGE APPROACH...SIMILAR TO KSFO.
MONTEREY BAY AREA TERMINALS...VFR THROUGH THE DAY TODAY WITH
WESTERLY GUSTS OF 15 TO 20 KT BY AFTERNOON. POSSIBLE SHOWERS
THROUGH 03Z. MODERATE CONFIDENCE.
&&
.MARINE...AS OF 3:45 AM PST THURSDAY...ISOLATED THUNDERSTORMS AND
AREAS OF SMALL HAIL ARE FORECAST FOR TODAY AS AN UNSTABLE AIRMASS
REMAINS OVER THE AREA. SOME THUNDERSTORMS COULD HAVE BRIEF
ROTATION.
A KING TIDE WILL COINCIDE WITH LARGE NORTHERLY SWELLS ENTERING THE
WATERS OVER THE NEXT FEW DAYS. A KING TIDE WILL BE PRESENT TODAY
AND CONTINUE THROUGH FRIDAY...WITH LOCALIZED FLOODING POSSIBLE
ACROSS LOW LYING AREAS NEAR THE COASTLINE. THESE HIGH TIDES WILL
BE PRESENT EACH MORNING BEGINNING TODAY AND CONTINUING INTO
FRIDAY. THE LOW TIDE WILL BE PRESENT EACH AFTERNOON/EARLY EVENING.
FOR DETAILED INFORMATION ON THE KING TIDE FOR A SPECIFIC AREA
ALONG THE COAST...PLEASE SEE WWW.CALIFORNIAKINGTIDES.ORG.
IN ADDITION...NORTHERLY SWELLS WILL CONTINUE TO BUILD TODAY. COMBINED
SEAS MAINLY BETWEEN 13 AND 16 FEET WITH A PERIOD OF 13 SECONDS
WILL BE PRESENT THURSDAY AFTERNOON INTO FRIDAY MORNING. THESE
SWELLS IN COMBINATION WITH THE KING TIDE MAY CAUSE ADDITION MINOR
COASTAL FLOODING. SWELLS WILL BEGIN TO SLOWLY SUBSIDE FRIDAY
AFTERNOON INTO THE WEEKEND.
PLEASE CONTINUE TO MONITOR THE FORECAST FOR THE LATEST INFORMATION
ON BOTH KING TIDE AND THE LARGE NORTHERLY SWELLS.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.TDAY...WINTER WEATHER ADVISORY...SANTA LUCIA MTNS AND LP FOREST
WINTER WEATHER ADVISORY...SANTA CRUZ MTNS
SCA...PT ARENA TO PT REYES 0-10 NM
SCA...PT REYES TO PIGEON PT 0-10 NM
SCA...PIGEON PT TO PT PINOS 0-10 NM
SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
SCA...PT ARENA TO PIGEON PT 10-60 NM
SCA...PIGEON PT TO PT PIEDRAS BLANCAS 10-60 NM
SCA...ROUGH BAR ADVISORY FOR SF BAR
&&
$$
PUBLIC FORECAST: RWW
AVIATION/MARINE: BELL
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AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
957 AM CST THU JAN 10 2013
.UPDATE...
AN UPDATE HAS BEEN DONE TO REFLECT CURRENT TRENDS.
12Z SOUNDING SHOWS THE DRY AIR OVER THE AREA IS CONSIDERABLE. SAID
DRY AIR IS HAVING THE EXPECTED IMPACT ON PRECIPITATION GENERATION
AND OVERALL TIMING INTO THE AREA. WHERE IT IS RAINING ON THE
LEADING EDGE IT IS FALLING OUT OF MID LEVEL CLOUDS AROUND 10KFT
AGL AND IS LIKELY MORE SPRINKLES THAN RAIN.
TOP DOWN SATURATION IS NON-LINEAR BY NATURE AND NOT HANDLED BY THE
MODELS. EACH SITUATION IS DIFFERENT AND THE SATURATION CAN OCCUR
FASTER/SLOWER THAN EXPECTED.
A COMBINATION OF RAP TRENDS USING CONDENSATION PRESSURE
DEFICITS/FORCING ALONG WITH THE HEAVY RAIN TOOL SUGGEST SPRINKLES
OR VERY LIGHT RAIN MAY REACH A KGGI TO KGBG LINE BY MID DAY WITH
THE BETTER RAIN JUST GETTING INTO THE EXTREME SOUTH.
DURING THE AFTERNOON HOURS A MORE SIGNIFICANT SLUG OF MOISTURE
BEGINS MOVING TOWARD THE AREA.
BY MID AFTERNOON SPRINKLES OR VERY LIGHT RAIN SHOULD BE AS FAR
NORTH AS A KALO/KOLZ TO ROUGHLY KRPJ LINE. THE IMMEDIATE HWY 20
CORRIDOR FROM DUBUQUE EAST SHOULD STILL BE DRY BUT WITH RAIN
ENCROACHING ON THE AREA.
IF THE RAP TRENDS ARE CORRECT...SATURATION IS RAPIDLY ACHIEVED
ACROSS THE NORTHERN CWFA DURING THE LATE AFTERNOON HOURS. RAIN
SHOULD BE FALLING ACROSS THE ENTIRE AREA DURING THE EVENING COMMUTE.
THE DRY AIR WILL ALSO RESULT IN EVAPORATIVE COOLING WHICH MAY
SUPPRESS TEMPERATURES DURING THE DAY. LIKE YESTERDAY...THE HIGH
FOR THE VERIFYING PERIOD WILL LIKELY OCCUR IN THE 6-8 PM TIME
FRAME. THE HIGH FOR THE CLIMATE DAY OF JAN 10TH WILL LIKELY OCCUR
BETWEEN 8 PM AND MIDNIGHT. ..08..
&&
.PREV DISCUSSION... /ISSUED 600 AM CST THU JAN 10 2013/
AVIATION...
VFR CONDITIONS WILL CONTINUE TO BE SEEN THROUGH 15Z THEN BANDS OF
LIGHT TO MODERATE RAIN WILL ARRIVE AT THE TERMINALS FROM NORTH
TO SOUTH FROM 16Z TO 22Z... AS A STORM SYSTEM APPROACHES FROM THE
SOUTHERN PLAINS. CONDITIONS TO DETERIORATE TO IFR AND POSSIBLY
LIFR WITHIN 2 TO 3 HRS OF THE RAIN STARTING. EXPECT WIDESPREAD
IFR TO LIFR CONDITIONS TONIGHT WITH PERIODS OF RAIN AND
DRIZZLE... WITH POSSIBLY VLIFR CONDITIONS IN DENSE FOG DEPENDING
ON THE TRACK OF THE SFC LOW. WINDS WILL MAINLY BE OUT OF THE E/SE
AT 4-12 KTS FOR MUCH OF THE TAF CYCLE... BUT BEGIN TO TURN MORE
S/SWLY TOWARD 12Z FRI IN WAKE OF PASSING SYSTEM.
PREV DISCUSSION... /ISSUED 337 AM CST THU JAN 10 2013/
SYNOPSIS...
CLOSED UPPER LOW WAS LOCATED OVER WEST TX AND HAS RECENTLY BEGUN
LIFTING NORTH IN RESPONSE TO ENERGY MOVING ONSHORE WEST COAST.
RAIN SHIELD ATTENDANT TO TX LOW ALSO LIFTING NORTH WITH TWO MAIN
AREAS... ONE OVER KS/OK/NW TX JUST NORTH OF MAIN CIRCULATION IN
ZONE OF STRONG ELEVATED MOISTURE TRANSPORT... AND THE OTHER MORE
LINEAR EXTENDING FROM TX/LA GULF COAST TO JUST S/E OF ST LOUIS
IN A SECONDARY BRANCH OF MOISTURE ADVECTION AND INCREASINGLY
DIFFLUENT FLOW ALOFT. 00Z RAOBS TO OUR SOUTH SHOW SIGNIFICANT
AMOUNTS OF MOISTURE WITH PRECIPITABLE WATER VALUES AT KOUN...
KLZK...KFWD AND KJAN RANGING FROM NEARLY 1.25 INCHES TO 1.4 INCHES
WHICH IS AROUND 250 TO NEARLY 350 PERCENT OF NORMAL.
SHORT TERM...TODAY AND TONIGHT...
MAIN FOCUS WITH INCOMING RAIN AND AMOUNTS... AND TEMPS. SHORT RANGE
MODELS IN PRETTY GOOD AGREEMENT ON CLOSED TX LOW LIFTING NEGATIVELY
TILTED THROUGH THE MID MISSISSIPPI VALLEY TONIGHT...PASSING NEAR TO
JUST SOUTH OF CWA. RAIN WILL OVERSPREAD THE CWA FROM SOUTH TO NORTH
TODAY AND INITIALLY BE MAINLY LIGHT. RAIN INTENSITY TO INCREASE
LATER TODAY (MAINLY SOUTH) AND ESPECIALLY THIS EVE TO JUST BEYOND
06Z WITH MAIN BOUT OF FORCING. BY THIS TIME... SIGNIFICANT MOISTURE
WILL BE IN PLACE WITH GEFS DEPICTING PRECIPITABLE WATER VALUES AT
LEAST 4 TO 5 STANDARD DEVIATIONS ABOVE NORMAL AND GENERALLY RANGING
FROM 1 TO 1.25 INCHES. THUS... SYSTEM WILL BE VERY WET WITH
WIDESPREAD 0.3 TO 0.75 INCH RAIN AMOUNTS THROUGH 12Z... WITH SOME
AREAS OF 1-1.5 INCHES ESPECIALLY JUST NW OF MAIN CENTER OF CIRCULATION
WITH ALONG AND S/E OF KIOW-KFEP LINE MOST LIKELY PORTION OF CWA TO
SEE SOME OF THESE HIGHER AMOUNTS FROM THE LOOKS OF THINGS ATTIM.
RAIN TAPER OFF IN INTENSITY AND AMOUNTS OVERNIGHT BUT ABUNDANT LOW
LEVEL MOISTURE AND LIFT SUPPORTIVE OF LIGHT RAIN AND DRIZZLE. SOME
AREAS OF FOG ALSO LIKELY TONIGHT AS SFC LOW MOVES ACROSS THE CWA.
AS FOR TEMPS... MANY AREAS LIKELY WILL SEE DAILY HIGHS OCCUR LATER
THIS EVE AS TEMPS CONTINUE TO CLIMB THROUGH ADVECTIVE PROCESSES.
WITH E/SE WINDS... CLOUDS AND RAIN OVERSPREADING AREA TODAY I STAYED
TOWARD THE COOLER SIDE OF GUIDANCE FOR TEMPS. I ALLOWED FOR A LITTLE
DROP OFF EARLY THIS EVE BEFORE TEMPS RISE. MCCLURE
LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY...
WARM SECTOR OF THE SURFACE CYCLONE PASSING WELL TO THE NORTHWEST
WILL SWEEP THROUGH THE AREA FRIDAY...RESULTING IN A POTENTIAL FOR
RECORD HIGH TEMPERATURES. TRAILING COLD FRONT WILL BRING MUCH COLDER
WEATHER THAT WILL PREVAIL THROUGH WEEKEND INTO NEXT WEEK. AN UPPER
LEVEL SYSTEM IS STILL ON TRACK TO BRING THE POTENTIAL FOR LIGHT SNOW
ACROSS MAINLY THE SOUTHEAST SATURDAY NIGHT INTO EARLY SUNDAY.
CHALLENGE FOR FRIDAY WILL BE WHETHER THE DEVELOPING SOUTHERLY WINDS
AND WARM ADVECTION CAN BREAK THROUGH THE MOIST LOW LEVEL INVERSION
AND STRATUS UNDER THE STRONGER ELEVATED WARM ADVECTION AND INFLUX OF
MUCH DRIER AIR ABOVE 900 MB. MODEL FORECAST SOUNDINGS OFFER A WIDE
RANGE OF SOLUTIONS...WITH THE NAM MOST PESSIMISTIC SUGGESTING LOW CLOUDS
AND POSSIBLE FOG HANGING ON THROUGH THE DAY WITH MUCH COOLER
TEMPERATURES...LIKELY DUE TO THE MODEL/S OVERDONE DEPICTION OF
LINGERING SNOW COVER. FOR NOW...WILL GO WITH A COMPROMISE CLOSER TO
A BLEND OF GFS AND ECMWF LOW LEVEL THERMAL FIELDS. THIS WOULD RESULT
IN AT LEAST PARTIAL CLEARING OF STRATUS INTO THE FAR SOUTH DURING
THE AFTERNOON ON 10 TO 15 KT SOUTHERLY SURFACE WINDS. FURTHER
NORTH...THE STRATUS WILL TAKE LONGER TO CLEAR IN THE SLIGHTLY WEAKER
SOUTH WINDS OVER THE COLDER GROUND AND PATCHES OF SNOW. THIS IMPACT
WILL BE GREATEST NORTH OF THE HIGHWAY 30 CORRIDOR WHERE AT LEAST
PATCHES OF OLD SNOW AND ICE SHOULD REMAIN. WILL GO WITH A MENTION OF
FOG AND DRIZZLE THERE FOR MUCH OF THE DAY...WHILE ANY FOG/HAZE OVER
THE CENTRAL AND SOUTH SHOULD DROP BELOW THRESHOLDS FOR MENTION IN
THE PUBLIC FORECAST BY LATE MORNING. OVERALL CONFIDENCE REMAINS
BELOW AVERAGE IN THE POTENTIAL FOR CLEARING AND THE DEPTH OF
MIXING...OVER ESPECIALLY THE CENTRAL AND NORTH AND WILL KEEP HIGHS
LIMITED TO THE MID 40S TO AROUND 50 NORTH OF I-80...WHILE THE FAR
SOUTH HAS A GOOD POTENTIAL TO BREAKOUT AND WARM INTO THE MID AND
UPPER 50S. THIS MAY THREATEN RECORD HIGHS SET LAST YEAR...ESPECIALLY
AT BRL. THESE ARE LISTED IN THE CLIMATE SECTION BELOW.
WILL CONTINUE WITH SLIGHTLY FASTER TIMING SHOWN BY NON-GFS MODEL
CONSENSUS...SWEEPING THE COLD FRONT THROUGH THE FORECAST AREA
FRIDAY NIGHT AND EXITING TO THE EAST BY SUNRISE SATURDAY. THIS
WILL RESULT IN CONTINUED NON-DIURNAL TEMPERATURE TRENDS FRIDAY NIGHT
INTO SATURDAY...WHERE TEMPERATURES SHOULD START FROM THE 30S NW TO
UPPER 40S SE EARLY...DROPPING TO THE 20S AND 30S BY LATE SATURDAY
AFTERNOON WITH COLD ADVECTION ON BRISK WEST WINDS. WITH VERY LITTLE
LOW OR MID LEVEL MOISTURE...NO PRECIPITATION IS EXPECTED WITH THE
FROPA OR IN THE SUBSIDENCE THAT FOLLOWS SATURDAY.
SATURDAY NIGHT...THE UPPER TROUGH AXIS REMAINS WELL TO THE WEST
KEEPING A FAST SW FLOW ALOFT OVER THE AREA. AN EMBEDDED SHORTWAVE
AND RIGHT ENTRANCE REGION TO A STRONG UPPER JET MOVING THROUGH THE
UPPER GREAT LAKES WILL SEND A WAVE OF LIFT OVER THE SOUTHEAST THIRD
OF THE FORECAST AREA. WHILE MOISTURE WILL BE LIMITED...CHANCE POPS
FOR LIGHT SNOW ARE JUSTIFIED FOR ESPECIALLY W CENTRAL IL. THE GFS
AND ECMWF THERMAL FIELDS WOULD SUPPORT A POSSIBILITY FOR MIXED
PRECIPITATION AT THE ONSET...WHICH WILL BE LEFT FOR CONSIDERATION IN
LATER FORECASTS. OTHERWISE...COLD ADVECTION WILL CONTINUE
WITH TEMPERATURES DROPPING INTO THE TEENS BY SUNDAY MORNING OVER THE
AREA.
SUNDAY THROUGH WEDNESDAY...COLD HIGH PRESSURE WILL RESULT IN BELOW
NORMAL TEMPERATURES SUNDAY AND MONDAY. A DEVELOPING UPPER LOW OVER
THE HUDSON BAY REGION WILL THEN PLACE A CYCLONIC NW FLOW OVERHEAD
TUE THROUGH WED. THE ACTIVE STORM TRACK STAYING NORTH OF THE
AREA...ALONG WITH GRADUAL MODERATION OF TEMPERATURES
ALOFT...SUGGESTS A PERIOD OF DRY WEATHER WITH SLIGHTLY WARMER
TEMPERATURES BY MID WEEK.
SHEETS
CLIMATE...
RECORD HIGHS FOR JANUARY 11...
MOLINE.........56 IN 2012
CEDAR RAPIDS...53 IN 2012
DUBUQUE........52 IN 2012
BURLINGTON.....55 IN 2012
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BISMARCK ND
548 AM CST THU JAN 10 2013
.DISCUSSION...
QUICK UPDATE FOR MORNING WIND AND TEMPERATURE TRENDS. AS OF 1145
UTC...THE SOUTH CENTRAL HAS SEEN SOUTHERLY WINDS INCREASE OVER THE
PAST ONE TO TWO HOURS WITH GUSTS OF 20 TO 30 KTS OBSERVED. THIS IS
MIXING DOWN TEMPERATURES FROM THE INVERSION WITH 37 DEGREES
OBSERVED AT THE NWS OFFICE AT THE AIRPORT...37 AT LINTON AND 36 AT
OAKES. BLENDED THE LATEST HRRR RUNS FOR WINDS THROUGH 18 UTC WHICH
ARE CAPTURING THIS MIXING AND BLENDED TO THE WARMEST TEMPERATURE
GUIDANCE TODAY...WHICH IS THE 00 UTC ECMWF. THUS...HAVE RAISED
HIGHS INTO LOW TO MID 40S FOR THE I-94 CORRIDOR IN LIGHT OF THE
CURRENT MIXED TEMPERATURES PRIOR TO INSOLATION.
&&
.AVIATION...
AT 545 AM CST THURSDAY...LOW PRESSURE WAS OVER SOUTHERN
SASKATCHEWAN WITH A COLD FRONT EXTENDING SOUTHWEST INTO NORTHWEST
MONTANA. A BROAD AREA OF VFR CONDITIONS EXTENDED ACROSS WEST AND
CENTRAL NORTH DAKOTA. AS THE SURFACE COLD FRONT ACROSS NORTHERN
MONTANA APPROACHES WESTERN NORTH DAKOTA AFTER 21Z/3 PM CST
THURSDAY...MVFR CONDITIONS WILL DEVELOP FROM KMOT TO KISN TO KDIK
TO KBIS...AND EVENTUALLY KJMS AFTER 00Z. A SIGNIFICANT WINTER
STORM WILL BRING MULTIPLE HAZARDS TO AVIATION ACROSS WEST AND
CENTRAL NORTH DAKOTA AFTER 06Z/FRIDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH SATURDAY MORNING
FOR NDZ001>005-009>013-017>023-025-031>037-040>048-050-051.
&&
$$
UPDATE...AYD
AVIATION...WAA
AREA FORECAST DISCUSSION
NWS MEDFORD OR
348 AM PST THU JAN 10 2013
.SHORT TERM...AN UPPER TROUGH WILL REMAIN OVER THE REGION TODAY
WHILE A COUPLE SHORTWAVES MOVE THROUGH THE AREA BRINGING SCATTERED
TO WIDESPREAD SHOWERS INTO THE AREA. THE UPPER TROUGH GRADUALLY
SHIFTS EASTWARD TONIGHT AND FRIDAY WITH A RIDGE OFFSHORE NUDGING
INTO THE AREA FRIDAY AND SATURDAY. HOWEVER ADDITIONAL SHORTWAVE
DISTURBANCES WILL BRING THE POTENTIAL FOR MORE PRECIPITATION
THROUGH SATURDAY NIGHT.
A LARGE BATCH OF SHOWERS IS VISIBLE ON SATELLITE AND MOVING INTO
WESTERN PORTIONS OF THE AREA THIS MORNING. SNOW LEVELS ARE AROUND
1000 FEET THIS MORNING. LIGHT ACCUMULATIONS IN SHOWERS ARE
EXPECTED IN WEST SIDE VALLEYS AS WELL AS THE MOUNTAINS THIS
MORNING. ALSO A SECOND SHORTWAVE IS VISIBLE JUST OFF ASTORIA AND IS
EXPECTED TO MOVE INTO NORTHERN PORTIONS OF THE CWA IN THE MID TO
LATE MORNING.
THE RUC MODEL SEEMS TO HAVE THE BEST HANDLE ON THE TRACK OF THE
SHORTWAVES AND PRECIPITATION. IT SHOWS SHOWERS INCREASING EARLY
THIS MORNING FROM THE CASCADES WEST. THE SECOND SHORTWAVE HAS A
WEAK SURFACE LOW ASSOCIATED WITH IT. THIS LOW IS FORECAST TO TRACK
SOUTH-SOUTHEAST MOVING INLAND AND INTO DOUGLAS COUNTY IN THE LATE
MORNING...THEN TRACKING EAST OF THE CASCADES IN THE AFTERNOON. AS
THIS FEATURE MOVES INLAND...EXPECT ADDITIONAL SHOWERS FROM THE
CASCADES WEST TO CONTINUE INTO THE AFTERNOON AS WELL AS SHOWERS
INCREASING EAST OF THE CASCADES DURING THE AFTERNOON. HAVE
EXTENDED THE WINTER WEATHER ADVISORIES THROUGH NOON DUE TO THE
EXPECTED CONTINUATION OF SHOWERS WITH THIS SECOND DISTURBANCE.
ALTHOUGH SHOWERS WILL CONTINUE THROUGH THE AFTERNOON...SNOW LEVELS
WILL RISE SLIGHTLY AND DAYTIME WARMING IS EXPECTED TO ALLOW LITTLE
ADDITIONAL SNOW IN THE VALLEYS. HIGHER TERRAIN WILL CONTINUE TO
SEE LIGHT ADDITIONAL SNOW ACCUMULATIONS THOUGH. THE RUC MODEL
INDICATES A POTENTIAL FOR SOME LIGHT TO MODERATE SNOW
ACCUMULATIONS OVER THE SOUTHERN OREGON CASCADES AND INTO NORTHERN
KLAMATH COUNTY. IF SNOW SHOWERS BECOME WIDESPREAD...MAY NEED TO ADD
OR EXTEND THE WINTER WEATHER ADVISORIES FOR THESE AREAS.
CURRENTLY...CONFIDENCE IN LOW IN THE HOW WIDESPREAD AND HEAVY
AFTERNOON SHOWERS WILL BE.
AREAS OF LIGHT SHOWERS ARE EXPECTED TO LINGER IN TO THE EVENING. OF
NOTE IS THE RUC SHOWS SHOWERS DECREASING FROM NORTH TO SOUTH OVER
THE AREA DURING THE EVENING.
THE UPPER TROUGH GRADUALLY SHIFTS EAST THURSDAY NIGHT AND FRIDAY.
HOWEVER ADDITIONAL DISTURBANCES ON THE BACKSIDE OF THE TROUGH ARE
FORECAST TO BRING ADDITIONAL LIGHT SHOWERS...ESPECIALLY FROM THE
CASCADES WEST THURSDAY NIGHT AND FRIDAY. THEN MODELS SHOW A
BRIEF BREAK IN THE PATTERN FRIDAY EVENING AS A RIDGE OFFSHORE
NUDGES INTO THE PACNW COAST.
ON SATURDAY...MODELS HAVE SHOWN VARIABILITY WITH A COUPLE SHORTWAVES
MOVING DOWN FROM THE NORTH AROUND THE RIDGE. THE GFS AND NAM ARE
STRONGER WITH THESE DISTURBANCES THAN THE ECMWF...ESPECIALLY WITH
THE SECOND SHORTWAVE SATURDAY EVENING AND NIGHT. BEHIND THESE
DISTURBANCES EXPECT NORTHERLY FLOW TO BRING VERY COLD TEMPERATURES
SUNDAY MORNING...ESPECIALLY EAST OF THE CASCADES. COLD
TEMPERATURES ARE FORECAST TO CONTINUE INTO MONDAY.
&&
.AVIATION...A VERY COLD AND SHOWERY AIR MASS WILL PERSIST
WITH A SERIES OF DISTURBANCES THROUGH FRIDAY. THIS WILL RESULT IN
PERIODS OF SNOW SHOWERS...MOST NUMEROUS IN SOUTHWEST OREGON.
THUNDERSTORMS ARE POSSIBLE ALONG THE COAST TONIGHT INTO THIS
MORNING. ADDITIONALLY...FREQUENT MOUNTAIN OBSCURATIONS WITH
VISIBILITY REDUCED IN SNOW SHOWERS CAN BE EXPECTED THROUGH TODAY.
SKY CONDITION TODAY WILL BE VARIABLE DUE TO THE SHOWERY NATURE OF
THE WEATHER...INCLUDING IFR DURING MORE INTENSE SNOW SHOWERS BUT
PREDOMINANTLY MVFR CEILINGS. SNOW SHOWERS WILL BE MORE NUMEROUS AT
NORTHWEST FACING SLOPES SUCH AS PARTS OF THE UMPQUA DIVIDE AND
SISKIYOU SUMMIT. THE FREEZING LEVEL WILL REMAIN BETWEEN 1000 AND
2000 FT MSL THROUGH FRIDAY. SK
&&
.PREV EXTENDED DISCUSSION... /ISSUED 245 PM PST WED JAN 9 2013/
.EXTENDED TERM...SUNDAY MORNING THROUGH WEDNESDAY NIGHT...
.THE LONG TERM FORECAST IS RATHER QUIET...ONCE THE WEEKEND SYSTEM
MAKES ITS EXIT OUT OF THE AREA. THE SHORTWAVE THAT IS EXPECTED TO
TRAVERSE THE NORTHERLY FLOW OVER THE REGION SATURDAY NIGHT AND
SUNDAY MORNING WILL EXIT TO THE SOUTH BY SUNDAY NIGHT...AND WITH IT
SO WILL PRECIPITATION CHANCES. WHAT PRECIPITATION THAT DOES FALL
DURING THE DAY SUNDAY WILL BE RELATIVELY LIGHT...AND WITH SNOW
LEVELS REMAINING ABOVE 2500 TO 3000 FEET...ANY IMPACTS WILL BE
CONFINED TO HIGHER ELEVATIONS.
ONCE THE SHORTWAVE FULLY EXITS THE AREA...HIGH AMPLITUDE TOWARDS THE
WEST COAST. THIS WILL PLACE THE FORECAST AREA UNDER THE EASTERN
PERIPHERY OF THE RIDGE AND UNDER NORTHERLY FLOW...BUT THE MAIN BELT
OF WESTERLIES WILL KEEP ANY SHORTWAVES WELL TO THE EAST THROUGHOUT
THE REST OF THE TERM. WITH THE CLEARER SKIES...THE USUAL SUSPECTS
WILL ARISE. THE FIRST IS THE THERMAL TROUGH...WHICH WILL PRODUCE
GUSTY WINDS ALONG RIDGE LINES ABOVE 5000 FEET. THE SECOND WILL BE
PERSISTENT MORNING FOG IN THE VALLEYS. LOW TEMPERATURES WILL STILL
HOVER AT OR BELOW FREEZING WITHIN MANY OF THE VALLEYS...SO FREEZING
FOG MAY BECOME AN ISSUE...AS ROADS AND OTHER SURFACES COULD BECOME
SLICK. OTHERWISE...EXPECT CLEARER SKIES...WITH TEMPERATURES RISING
TO NEAR OR EVEN SLIGHTLY ABOVE SEASONAL NORMALS BY MIDWEEK. -BPN
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR ORZ027-028.
FROST ADVISORY UNTIL 8 AM PST THIS MORNING FOR ORZ021-022.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY ABOVE 1000 FEET FOR
FOR ORZ021-022.
FREEZE WARNING UNTIL 8 AM PST THIS MORNING FOR ORZ021-022.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY ABOVE 1000 FEET FOR
FOR ORZ023.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR ORZ025.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR ORZ024-026.
CA...WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR
CAZ081>083.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY ABOVE
1500 FEET FOR FOR CAZ080.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS FROM 1 PM THIS
AFTERNOON TO 7 AM PST FRIDAY FOR PZZ350-356.
HAZARDOUS SEAS WARNING FROM 1 PM THIS AFTERNOON TO 4 AM PST
FRIDAY FOR PZZ350-356.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 PM PST THIS
AFTERNOON FOR PZZ350-356.
SMALL CRAFT ADVISORY FOR WINDS UNTIL 7 AM PST FRIDAY FOR
PZZ370-376.
HAZARDOUS SEAS WARNING FROM 10 AM THIS MORNING TO 4 AM PST
FRIDAY FOR PZZ370-376.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 AM PST THIS
MORNING FOR PZZ370-376.
$$
CC
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
936 AM EST THU JAN 10 2013
.DISCUSSION...STARTING OUT GENERALLY DRY ACROSS THE REGION THIS
MORNING IN SPITE OF A VERY MOIST AIRMASS FROM MIDDLE TN EASTWARD
INTO MAINLY THE SW HALF OF EAST TN. THE 12Z OHX SOUNDING HAD
PRECIPITABLE WATER (PW) VALUE OF JUST OVER 1.35 INCHES (300 PERCENT
OF NORMAL). 12Z RNK SOUNDING MUCH DRIER WITH LESS THAN 1/2 INCH PW.
12Z UPPER PLOTS SHOW A LIGHT SOUTHERLY FLOW AT 850 MB LEVEL...SO A
BIT OF DOWNSLOPING IS LIKELY AFFECTING PARTS OF NE TN AND SW VA.
ANOTHER FACTOR FOR LACK OF RAIN THIS MORNING IN OUR AREA MAY BE THE
STRONG CONVECTION ALREADY OCCURRING OVER THE LOWER MS VALLEY REGION.
LATEST RUC MODEL RUN AND SREF ARE ONLY SHOWING SOME SCATTERED AREAS
OF RAIN DEVELOPING OVER OUR WRN MOST COUNTIES LATER TODAY. THUS...
PLAN TO DO A MID MORNING UPDATE TO LOWER RAIN CHANCES.
MAX TEMP FORECAST IS PROBABLY ON TRACK...ALTHO WARM FRONT IS STILL
TO OUR SOUTH. 14Z TEMPS WERE VERY MILD AND ALREADY ABOVE SEASONAL
HIGHS FOR MID JANUARY...SO ANY BREAKS OF SUNSHINE OR DOWNSLOPING
SHOULD SEND HIGHS INTO THE UPPER 50S TO MID 60S.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 65 54 68 57 72 / 60 60 60 30 30
KNOXVILLE MCGHEE TYSON AIRPORT, TN 63 50 67 55 71 / 50 50 60 30 30
OAK RIDGE, TN 63 50 66 55 71 / 60 50 60 20 30
TRI CITIES AIRPORT, TN 62 43 63 49 69 / 30 30 40 20 20
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
TG
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1157 AM CST THU JAN 10 2013
.DISCUSSION...
ISSUED 1040 AM CST THU JAN 10 2013
FORECAST GENERALLY ON TRACK TODAY AND JUST A FEW MINOR ADJUSTMENTS
WITH INCREASING WIND SPEEDS A BIT AND LIMIT THUNDERSTORM CHANCES
TO AREAS SOUTH OF I-72 THIS AFTERNOON.
SCATTERED LIGHT RAIN SHOWERS HAVE SPREAD NORTHWARD INTO CENTRAL
IL BY LATE MORNING WITH HEAVIER SHOWERS OVER SOUTHERN IL FROM I-64
SOUTH AND EAST OF I-57 AND LIFTING NORTHWARD. LATE MORNING
SURFACE MAP SHOWS 1011 MB LOW PRESSURE ALONG THE WESTERN RED RIVER
VALLEY ON THE OK/TX BORDER WHILE 557 DM 500 MB LOW NEAR THAT LOCATION.
QUICKER HRRR MODEL HANDLING QPF FIELDS BETTER THIS MORNING THAN
SLOWER NAM AND RAP MODELS SO LEANED ON THIS MODEL FOR FORECAST
INTO THIS EVENING. RAIN SHOWERS TO BECOME MORE WIDESPREAD THIS
AFTERNOON AND EVENING AND HEAVIEST RAINFALL TO OCCUR SE OF I-55
WITH ISOLATED THUNDERSTORMS POSSIBLE. RAINFALL AMOUNTS TODAY AND
THU TO RANGE FROM 1-1.25 INCHES WITH LOCALLY 1.25-1.5 INCHES SW OF
SPRINGFIELD AND SE OF I-70. LITTLE WABASH RIVER AT CLAY CITY
FORECAST TO RISE ABOVE THE 16 FOOT FLOOD STAGE FRIDAY AFTERNOON.
MODELS EJECT STRONG CUTOFF NEGATIVE TITLED UPPER LEVEL LOW NE INTO
WEST CENTRAL MO BY MIDNIGHT TONIGHT AND NORTHWEST IL BY DAWN FRI.
IMPRESSIVE PRECIPITATABLE WATER VALUES OF 1.25-1.50 INCHES SPREAD
INTO CENTRAL/SE IL BY THIS EVENING AIDED BY 35-50 KT SSW 850 MB
JET WITH HIGHEST PRECIP VALUES IN SE IL. TEMPS CURRENTLY IN THE
MID 30S TO LOWER 40S WITH COOLEST READINGS NEAR 35F AT GALESBURG
AND MACOMB WHERE LINGERING 1-2 INCH SNOW PACK. HIGHS TO REACH THE
MID 40S NORTH AND LOWER 50S SE IL. TEMPS TO SLOWLY RISE TONIGHT AS
WARM FRONT LIFTS NORTHWARD TO BETWEEN 50-55F BY SUNRISE FRIDAY.
07
&&
.AVIATION...
ISSUED 1155 AM CST THU JAN 10 2013
VFR CONDITIONS AT NOON ACROSS THE CENTRAL IL TERMINAL AIRPORTS
WILL QUICKLY DETERIORATE DURING THE AFTERNOON WITH IFR VSBYS AND
CEILINGS GRADUALLY SETTING IN WITH DEVELOPING LIGHT TO MODERATE
RAIN SHOWERS. COULD BE ISOLATED THUNDERSTORMS LATER THIS AFTERNOON
AND EVENING WITH BEST CHANCES ALONG AND SOUTH OF I-72 BUT TOO
ISOLATED IN NATURE TO PIN POINT IN TAFS AT THIS TIME. RAIN SHOWERS
SHOULD DIMINISH FROM SW TO NE DURING BETWEEN 08Z-11Z OVERNIGHT
WITH IFR CEILINGS AND VSBYS LINGERING WITH LOW CLOUDS AND FOG.
HAVE CEILINGS AND VSBYS GRADUALLY LIFTING TO MVFR BY LATE FRI
MORNING WITH BMI AND CMI LATEST TO OCCUR NEAR OR AFTER 16Z. ESE
WINDS 10-15 KTS TO TURN SE AFTER 21Z THIS AFTERNOON AND
EVENING...THEN TURN SSW DURING OVERNIGHT AS WARM FRONT LIFTS
NORTHWARD ACROSS CENTRAL IL.
557 DM 500 MB CUTOFF LOW ALONG THE RED RIVER ON THE TX/OK BORDER
AND 1011 MB SURFACE LOW NEARBY TO EJECT NE INTO WEST CENTRAL MO BY
06Z/MIDNIGHT TONIGHT...INTO CENTRAL/NW IL BY 12Z/6 AM FRI AND NEAR
SE LOWER MI AND OHIO BORDER BY 18Z/NOON FRI. IFR CONDITIONS
CURRENTLY OVER MUCH OF MO AND SOUTHERN IL TO SPREAD NE ACROSS
CENTRAL IL DURING EARLY/MID AFTEROON AND LINGER THROUGH EARLY FRI
MORNING THEN LIFT TO MVFR BETWEEN 14Z-16Z FRIDAY. VSBYS COULD GET
BELOW 1 MILE AT TIMES TONIGHT AND CELINGS BELOW 500 FT (LIFR) AT
PIA AND BMI WHERE FOG MORE WIDESPREAD WITH THE RAIN SHOWERS.
07
&&
.PREV DISCUSSION...
ISSUED 312 AM CST THU JAN 10 2013
THE UPPER LOW THAT WE HAVE BEEN TRACKING THE LAST FEW DAYS HAS
MADE SOME GOOD PROGRESS OVER THE LAST SEVERAL HOURS...AND WAS
CENTERED IN CENTRAL TEXAS AT 3 AM PER WATER VAPOR IMAGERY. LARGE
AREA OF RAIN HAS BEGUN SPREADING NORTHWARD ACROSS SOUTHERN MISSOURI
AND KENTUCKY. FORECAST CONCERNS INVOLVING THIS FEATURE INCLUDE
HEAVY RAIN POTENTIAL...AS WELL AS ABNORMALLY MILD WEATHER OVER THE
NEXT 24-36 HOURS. THIS WEEKEND...THE POTENTIAL FOR WINTRY MIXTURE
IS A CONCERN FOR SATURDAY NIGHT AND EARLY SUNDAY.
SHORT TERM...TODAY THROUGH FRIDAY NIGHT...
RAIN WILL CONTINUE TO SPREAD NORTHWARD TODAY AS THE UPPER LOW
LIFTS INTO KANSAS. LATEST MODEL GUIDANCE SUGGESTS AREAS NORTH OF
I-74 MAY HOLD OFF ON THE RAIN UNTIL AROUND MIDDAY...BUT WILL
CONTINUE WITH CATEGORICAL POPS EVERYWHERE THIS AFTERNOON AND MUCH
OF TONIGHT. MOST OF THE MODELS CONTINUE TO SHOW THE LOW SHEARING
OUT INTO AN OPEN WAVE AS IT LIFTS TOWARD NORTHERN ILLINOIS... AND
PRECIPITATION SHOULD RAPIDLY TAPER OFF FROM WEST TO EAST AFTER
MIDNIGHT. DRY WEATHER IS EXPECTED ON FRIDAY AND FRIDAY NIGHT.
HAVE MAINTAINED THE NON-DIURNAL TEMPERATURE TRENDS TONIGHT AND
FRIDAY NIGHT...AND THE UNSEASONABLY MILD HIGHS ON FRIDAY. HAVE
GONE WITH HIGHS NEAR 60 IN MOST AREAS...WITH LOWER 60S SOUTH OF
I-70. TEMPERATURES WILL BE APPROACHING RECORDS IN MANY AREAS.
LONG TERM...SATURDAY THROUGH WEDNESDAY...
FOCUS TURNS TOWARD DEEP LONG WAVE TROUGHING OVER THE ROCKIES
EARLY THIS WEEKEND...RESULTING IN RIDGING ALONG THE EAST COAST.
THE COLD FRONT WHICH WILL CROSS THE AREA EARLY ON SATURDAY WILL
BECOME HUNG UP ALONG THE OHIO RIVER BY SATURDAY EVENING...AS IT
BECOMES PARALLEL TO THE UPPER FLOW. WAVES OF LOW PRESSURE RIDING
NORTHEAST ALONG THE FRONT WILL SPREAD PRECIPITATION BACK NORTHWARD
SATURDAY EVENING ACROSS MOST OF THE CWA...LINGERING MUCH OF THE
NIGHT. STILL AM CONCERNED ABOUT POTENTIAL FOR FREEZING RAIN OR
SLEET. LATEST MODEL GUIDANCE HAS SHIFTED THE AXIS OF CONCERN A BIT
FURTHER EAST...WITH A WARM NOSE OF 850 MB TEMPERATURES OF 5 TO 7
DEGREES CELSIUS FROM ABOUT CHAMPAIGN AND DANVILLE SOUTHWEST
THROUGH TAYLORVILLE ESPECIALLY AFTER MIDNIGHT. AREAS ALONG AND
WEST OF I-55 WILL TREND MORE TOWARD SNOW DURING THE EVENING...
WITH SOME POTENTIAL FOR A COUPLE INCHES OF ACCUMULATION. THE
SOUTHEAST CWA IS EXPECTED TO REMAIN WARM ENOUGH FOR RAIN SATURDAY
NIGHT AND SUNDAY.
THE FRONT WILL REMAIN HUNG FOR A FEW DAYS...BUT IS EXPECTED TO SAG
FAR ENOUGH SOUTH THAT PRECIPITATION CHANCES SHOULD BE SOUTH OF OUR
AREA FROM MONDAY ONWARD. HOWEVER...THE LATEST ECMWF HINTS THAT
SOME LOW POPS MAY NEED TO BE ADDED IN THE FAR SOUTHEAST CWA MONDAY
AND MONDAY NIGHT. WILL CONTINUE TO MONITOR THIS POTENTIAL.
HYDROLOGY...
HAVE SOME CONCERNS REGARDING HEAVY RAIN POTENTIAL OVER THE NEXT
COUPLE DAYS. HIGH PRECIPITABLE WATER VALUES OF AROUND 1.5 INCHES
OBSERVED ON THE EVENING UPPER AIR SOUNDING FROM LITTLE ROCK... AND
NAM/GFS MODELS SHOW THIS ADVECTING NORTHEAST INTO ILLINOIS THIS
AFTERNOON...PERSISTING THROUGH ABOUT MIDNIGHT. PER CLIMATOLOGY...
SUCH VALUES IN THIS AREA IN JANUARY ARE ABOUT OFF THE CHARTS.
CURRENTLY AM FORECASTING A WIDESPREAD INCH OF RAIN OVER THE AREA
THROUGH FRIDAY MORNING...WITH SOME LOCALLY HIGHER AMOUNTS. WITH
THE COLDER AIR THAT HAD BEEN PRESENT THE LAST SEVERAL DAYS...THE
GROUND IS SOMEWHAT FROZEN AND SOME RUNOFF IS LIKELY. MOST OF THE
SNOW IS PRETTY MUCH GONE NOW EXCEPT IN THE NORTHWEST AND SOUTHEAST
CORNERS OF THE CWA...SO SNOW MELT SHOULD NOT BE MUCH OF A PROBLEM.
MOST RIVERS HAVE BEEN RUNNING RATHER LOW AND SHOULD BE ABLE TO
TAKE ON THIS RUNOFF...BUT SOME MINOR FLOODING IS POSSIBLE ALONG
THE LITTLE WABASH RIVER. HOWEVER...WITH THE FRONT HANGING UP NEAR
THE OHIO RIVER SATURDAY EVENING...ANOTHER ROUND OF HEAVIER RAIN IS
POSSIBLE SOUTH OF I-70 THIS WEEKEND.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1044 AM CST THU JAN 10 2013
.DISCUSSION...
ISSUED 1040 AM CST THU JAN 10 2013
FORECAST GENERALLY ON TRACK TODAY AND JUST A FEW MINOR ADJUSTMENTS
WITH INCREASING WIND SPEEDS A BIT AND LIMIT THUNDERSTORM CHANCES
TO AREAS SOUTH OF I-72 THIS AFTERNOON.
SCATTERED LIGHT RAIN SHOWERS HAVE SPREAD NORTHWARD INTO CENTRAL
IL BY LATE MORNING WITH HEAVIER SHOWERS OVER SOUTHERN IL FROM I-64
SOUTH AND EAST OF I-57 AND LIFTING NORTHWARD. LATE MORNING
SURFACE MAP SHOWS 1011 MB LOW PRESSURE ALONG THE WESTERN RED RIVER
VALLEY ON THE OK/TX BORDER WHILE 557 DM 500 MB LOW NEAR THAT LOCATION.
QUICKER HRRR MODEL HANDLING QPF FIELDS BETTER THIS MORNING THAN
SLOWER NAM AND RAP MODELS SO LEANED ON THIS MODEL FOR FORECAST
INTO THIS EVENING. RAIN SHOWERS TO BECOME MORE WIDESPREAD THIS
AFTERNOON AND EVENING AND HEAVIEST RAINFALL TO OCCUR SE OF I-55
WITH ISOLATED THUNDERSTORMS POSSIBLE. RAINFALL AMOUNTS TODAY AND
THU TO RANGE FROM 1-1.25 INCHES WITH LOCALLY 1.25-1.5 INCHES SW OF
SPRINGFIELD AND SE OF I-70. LITTLE WABASH RIVER AT CLAY CITY
FORECAST TO RISE ABOVE THE 16 FOOT FLOOD STAGE FRIDAY AFTERNOON.
MODELS EJECT STRONG CUTOFF NEGATIVE TITLED UPPER LEVEL LOW NE INTO
WEST CENTRAL MO BY MIDNIGHT TONIGHT AND NORTHWEST IL BY DAWN FRI.
IMPRESSIVE PRECIPITATABLE WATER VALUES OF 1.25-1.50 INCHES SPREAD
INTO CENTRAL/SE IL BY THIS EVENING AIDED BY 35-50 KT SSW 850 MB
JET WITH HIGHEST PRECIP VALUES IN SE IL. TEMPS CURRENTLY IN THE
MID 30S TO LOWER 40S WITH COOLEST READINGS NEAR 35F AT GALESBURG
AND MACOMB WHERE LINGERING 1-2 INCH SNOW PACK. HIGHS TO REACH THE
MID 40S NORTH AND LOWER 50S SE IL. TEMPS TO SLOWLY RISE TONIGHT AS
WARM FRONT LIFTS NORTHWARD TO BETWEEN 50-55F BY SUNRISE FRIDAY.
07
&&
.AVIATION...
ISSUED 557 AM CST THU JAN 10 2013...FOR THE 12Z TAFS
RAIN WILL OVERSPREAD THE AREA FROM THE SOUTH AS LOW PRESSURE IN
EASTERN TEXAS LIFTS NORTH INTO THE PLAINS. BASED ON FORECAST
SOUNDINGS AND UPSTREAM OBSERVATIONS...WE EXPECT VFR CONDITIONS
WILL QUICKLY DROP TO IFR AFTER RAIN STARTS. CIGS WILL DIP BELOW 1K
FT WITH VIS MOST LIKELY IN THE MVFR RANGE DURING RAIN.
RAIN WILL BE SCATTERED DURING THE DAY...BUT IFR CONDITIONS ARE
GENERALLY EXPECTED TO CONTINUE DURING BREAKS IN THE RAIN. RAIN
WILL BECOME MORE STEADY TONIGHT AS THE WARM FRONT LIFTS NORTH
THROUGH ILLINOIS AND THE SURFACE LOW LIFTS NORTH THROUGH MISSOURI
AND IOWA. RAINFALL SHOULD DIMINISH AFTER MIDNIGHT...WITH RAIN
ENDING IN MOST AREAS BY SUNRISE ON FRIDAY. PREVAILING CONDITIONS
MAY DIP TO LIFR OR VLIFR THIS EVENING AND OVERNIGHT DUE TO LOW
CEILINGS. FOG WILL BE POSSIBLE AS WELL...BUT WIDESPREAD DENSE FOG
IS NOT EXPECTED AT THIS POINT.
WINDS WILL BE SOUTHEAST AND INCREASE TO 12-15KT TODAY...THEN SHIFT
TO THE SOUTHWEST AFTER THE WARM FRONT PASSES TONIGHT.
SHIMON
&&
.PREV DISCUSSION...
ISSUED 312 AM CST THU JAN 10 2013
THE UPPER LOW THAT WE HAVE BEEN TRACKING THE LAST FEW DAYS HAS
MADE SOME GOOD PROGRESS OVER THE LAST SEVERAL HOURS...AND WAS
CENTERED IN CENTRAL TEXAS AT 3 AM PER WATER VAPOR IMAGERY. LARGE
AREA OF RAIN HAS BEGUN SPREADING NORTHWARD ACROSS SOUTHERN MISSOURI
AND KENTUCKY. FORECAST CONCERNS INVOLVING THIS FEATURE INCLUDE
HEAVY RAIN POTENTIAL...AS WELL AS ABNORMALLY MILD WEATHER OVER THE
NEXT 24-36 HOURS. THIS WEEKEND...THE POTENTIAL FOR WINTRY MIXTURE
IS A CONCERN FOR SATURDAY NIGHT AND EARLY SUNDAY.
SHORT TERM...TODAY THROUGH FRIDAY NIGHT...
RAIN WILL CONTINUE TO SPREAD NORTHWARD TODAY AS THE UPPER LOW
LIFTS INTO KANSAS. LATEST MODEL GUIDANCE SUGGESTS AREAS NORTH OF
I-74 MAY HOLD OFF ON THE RAIN UNTIL AROUND MIDDAY...BUT WILL
CONTINUE WITH CATEGORICAL POPS EVERYWHERE THIS AFTERNOON AND MUCH
OF TONIGHT. MOST OF THE MODELS CONTINUE TO SHOW THE LOW SHEARING
OUT INTO AN OPEN WAVE AS IT LIFTS TOWARD NORTHERN ILLINOIS... AND
PRECIPITATION SHOULD RAPIDLY TAPER OFF FROM WEST TO EAST AFTER
MIDNIGHT. DRY WEATHER IS EXPECTED ON FRIDAY AND FRIDAY NIGHT.
HAVE MAINTAINED THE NON-DIURNAL TEMPERATURE TRENDS TONIGHT AND
FRIDAY NIGHT...AND THE UNSEASONABLY MILD HIGHS ON FRIDAY. HAVE
GONE WITH HIGHS NEAR 60 IN MOST AREAS...WITH LOWER 60S SOUTH OF
I-70. TEMPERATURES WILL BE APPROACHING RECORDS IN MANY AREAS.
LONG TERM...SATURDAY THROUGH WEDNESDAY...
FOCUS TURNS TOWARD DEEP LONG WAVE TROUGHING OVER THE ROCKIES
EARLY THIS WEEKEND...RESULTING IN RIDGING ALONG THE EAST COAST.
THE COLD FRONT WHICH WILL CROSS THE AREA EARLY ON SATURDAY WILL
BECOME HUNG UP ALONG THE OHIO RIVER BY SATURDAY EVENING...AS IT
BECOMES PARALLEL TO THE UPPER FLOW. WAVES OF LOW PRESSURE RIDING
NORTHEAST ALONG THE FRONT WILL SPREAD PRECIPITATION BACK NORTHWARD
SATURDAY EVENING ACROSS MOST OF THE CWA...LINGERING MUCH OF THE
NIGHT. STILL AM CONCERNED ABOUT POTENTIAL FOR FREEZING RAIN OR
SLEET. LATEST MODEL GUIDANCE HAS SHIFTED THE AXIS OF CONCERN A BIT
FURTHER EAST...WITH A WARM NOSE OF 850 MB TEMPERATURES OF 5 TO 7
DEGREES CELSIUS FROM ABOUT CHAMPAIGN AND DANVILLE SOUTHWEST
THROUGH TAYLORVILLE ESPECIALLY AFTER MIDNIGHT. AREAS ALONG AND
WEST OF I-55 WILL TREND MORE TOWARD SNOW DURING THE EVENING...
WITH SOME POTENTIAL FOR A COUPLE INCHES OF ACCUMULATION. THE
SOUTHEAST CWA IS EXPECTED TO REMAIN WARM ENOUGH FOR RAIN SATURDAY
NIGHT AND SUNDAY.
THE FRONT WILL REMAIN HUNG FOR A FEW DAYS...BUT IS EXPECTED TO SAG
FAR ENOUGH SOUTH THAT PRECIPITATION CHANCES SHOULD BE SOUTH OF OUR
AREA FROM MONDAY ONWARD. HOWEVER...THE LATEST ECMWF HINTS THAT
SOME LOW POPS MAY NEED TO BE ADDED IN THE FAR SOUTHEAST CWA MONDAY
AND MONDAY NIGHT. WILL CONTINUE TO MONITOR THIS POTENTIAL.
HYDROLOGY...
HAVE SOME CONCERNS REGARDING HEAVY RAIN POTENTIAL OVER THE NEXT
COUPLE DAYS. HIGH PRECIPITABLE WATER VALUES OF AROUND 1.5 INCHES
OBSERVED ON THE EVENING UPPER AIR SOUNDING FROM LITTLE ROCK... AND
NAM/GFS MODELS SHOW THIS ADVECTING NORTHEAST INTO ILLINOIS THIS
AFTERNOON...PERSISTING THROUGH ABOUT MIDNIGHT. PER CLIMATOLOGY...
SUCH VALUES IN THIS AREA IN JANUARY ARE ABOUT OFF THE CHARTS.
CURRENTLY AM FORECASTING A WIDESPREAD INCH OF RAIN OVER THE AREA
THROUGH FRIDAY MORNING...WITH SOME LOCALLY HIGHER AMOUNTS. WITH
THE COLDER AIR THAT HAD BEEN PRESENT THE LAST SEVERAL DAYS...THE
GROUND IS SOMEWHAT FROZEN AND SOME RUNOFF IS LIKELY. MOST OF THE
SNOW IS PRETTY MUCH GONE NOW EXCEPT IN THE NORTHWEST AND SOUTHEAST
CORNERS OF THE CWA...SO SNOW MELT SHOULD NOT BE MUCH OF A PROBLEM.
MOST RIVERS HAVE BEEN RUNNING RATHER LOW AND SHOULD BE ABLE TO
TAKE ON THIS RUNOFF...BUT SOME MINOR FLOODING IS POSSIBLE ALONG
THE LITTLE WABASH RIVER. HOWEVER...WITH THE FRONT HANGING UP NEAR
THE OHIO RIVER SATURDAY EVENING...ANOTHER ROUND OF HEAVIER RAIN IS
POSSIBLE SOUTH OF I-70 THIS WEEKEND.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION...CORRECTED RECORD HIGHS FOR FRIDAY
NWS QUAD CITIES IA IL
319 PM CST THU JAN 10 2013
.SYNOPSIS...
12Z UA ANALYSIS HAS THE CUT OFF LOW IN WEST TEXAS WITH A 850MB
WARM FRONT RUNNING FROM CENTRAL OKLAHOMA INTO SOUTHEAST KANSAS. A
VERY SHARP 850MB MOISTURE GRADIENT RAN FROM NORTHWEST MISSOURI
INTO THE OHIO VALLEY. RADAR TRENDS THROUGH THE MORNING AND
AFTERNOON SHOW PLENTY OF VIRGA FROM NORTHERN IOWA INTO NORTHERN
ILLINOIS WITH SFC RAIN FROM SOUTHERN IOWA INTO CENTRAL ILLINOIS.
18Z SFC ANALYSIS HAS THE LOW IN SOUTHWEST OKLAHOMA WITH A
DEVELOPING BOUNDARY FROM CENTRAL OKLAHOMA TO NEAR KMEM. DEW POINTS
WERE IN THE 20S ACROSS THE GREAT LAKES WITH 30S AND 40S FROM THE
CENTRAL PLAINS INTO THE OHIO VALLEY. DEW POINTS IN THE 50S WERE IN
THE LOWER MISSISSIPPI VALLEY.
&&
.SHORT TERM...LATE THIS AFTERNOON AND TONIGHT
THE MOISTURE SURGE COMING UP FROM THE SOUTH IS STARTING TO WIN
OVER THE DRY AIR. SPOTTY RAIN OR DRIZZLE IS NOW OVER ROUGHLY THE
SOUTHERN HALF OF THE CWFA WITH SPRINKLES OR VERY SPOTTY RAIN
DEVELOPING OVER THE NORTHERN HALF.
RAP TRENDS INDICATE THAT A VERY RAPID TOP DOWN SATURATION WILL
OCCUR LATE THIS AFTERNOON. SO BY THE EVENING COMMUTE THERE SHOULD
BE FAIRLY WIDESPREAD VERY LIGHT RAIN OR DRIZZLE OCCURRING ACROSS
THE AREA.
TEMPERATURES WILL SLOWLY CLIMB LATE THIS AFTERNOON AS MOISTURE
CONTINUES TO SURGE INTO THE AREA. HIGH TEMPERATURES FOR THE
VERIFYING PERIOD WILL LIKELY OCCUR IN THE 6-8 PM TIME FRAME.
LIKEWISE...OVERNIGHT LOWS WILL LIKELY OCCUR IN THE 7-8 PM TIME
FRAME FOLLOWED BY STEADY OR SLOWLY RISING TEMPERATURES.
TONIGHT...STRONG FORCING MOVES ACROSS THE AREA DURING THE EVENING
WITH A FULLY SATURATED ATMOSPHERE. THE HEAVY RAIN TOOL SUGGESTS
THE EVENING HOURS WILL LIKELY ACCOUNT FOR MUCH OF THE RAINFALL
FROM THIS EVENT. AFTER MIDNIGHT...WIDESPREAD DRIZZLE WILL BE SEEN
BUT ANOTHER ROUND OF FORCING WILL LIKELY ALLOW SOME ADDITIONAL
RAIN TO OCCUR.
ANOTHER CONCERN TONIGHT IS FOG. THERE IS STILL A RESPECTABLE SNOW
FIELD OVER ROUGHLY THE NORTHERN THIRD OF THE CWFA. ADVECTING
MOISTURE INTO THE AREA ALONG WITH RAIN SHOULD ALLOW PATCHY OR SOME
AREAS OF FOG TO DEVELOP LATE THIS EVENING AS WINDS DIMINISH. AFTER
MIDNIGHT WINDS DROP OFF ACROSS THE NORTHWEST THIRD TO 40 PERCENT
OF THE CWFA WITH THE PASSAGE OF THE SFC LOW. AT THIS TIME THE RISK
FOR DENSE FOG WILL BE THE GREATEST.
THEREFORE...WILL ISSUE A DENSE FOG ADVISORY FOR THE MAIN SNOW
FIELD AND WHERE WINDS ARE PROGGED TO BE LIGHT. IT IS HIGHLY LIKELY
THAT THE DENSE FOG ADVISORY MAY HAVE TO BE EXPANDED DURING THE
EVENING OR OVERNIGHT HOURS. ..08..
.LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY...
HIGH TEMPERATURES FOR FRIDAY ARE A LARGE QUESTION MARK THIS
FORECAST. THE MAIN COMPLICATING FACTOR IS IN HOW QUICKLY THE LOW
CLOUDS CLEAR FROM SOUTH TO NORTH WITH THE ASSOCIATED CLEARING OF THE
FOG AND DRIZZLE. MODELS HAVE BEEN STRUGGLING WITH THIS ISSUE...WITH
MANY OF THEM KEEPING A TRAPPED LOWER LAYER OF LOW CLOUDS AND FOG
WITH A STRONG ELEVATED MIXED LAYER OVER THE TOP OF IT.
HOWEVER...THEY ALSO DEPICT STRONG SURFACE WINDS...WHICH DOES NOT
MATCH WELL WITH A TRAPPED LOW LEVEL INVERSION. A LOOK AT THE MODEL
INITIALIZATION SHOWS THAT NAM12 MODEL SNOW DEPTH INITIALIZATION IS
FAR TOO FAR SOUTH...WITH 1 INCH OR MORE OF SNOW DEPTH INTO NORTHERN
MISSOURI. GEM AND RUC ARE CLOSER TO REALITY. GFS MODEL SNOW DEPTH
INITIALIZATION MAY NOT BE ANY BETTER THAN THE NAM12...BUT CANNOT
CHECK ON THAT AT THIS TIME. THUS...HAVE DECIDED TO DEFINITELY ALLOW
THE CLOUDS TO CLEAR OUT OF THE SNOW FREE AREAS ACROSS THE SOUTHERN
HALF TO TWO THIRDS OF THE FORECAST AREA...ALLOWING HIGH TEMPS TO GET
INTO THE MID TO UPPER 50S IN THE AFTERNOON. HOWEVER THE NORTH IS A
WHOLE SEPARATE CAN OF WORMS...WITH THE LOW CLOUDS FOG AND DRIZZLE
HANGING ON INTO THE AFTERNOON AND KEEPING TEMPERATURES IN THE 40S TO
NEAR 50 FOR THE MOST PART. THIS MAKES A LARGE RANGE ACROSS THE
FORECAST AREA IN MAX TEMPS...AND STILL LEAVES US WITH A LARGE BUST
POTENTIAL FOR THIS FORECAST. WITH THIS EXTRAORDINARY WARMTH...THE
RECORD HIGH TEMPERATURE FOR BURLINGTON IS AT RISK...AND WE WILL BE
CLOSE AT OTHER LOCATIONS. FOR REFERENCE...HAVE INCLUDED RECORD HIGHS FOR
FRIDAY BELOW.
OF COURSE...THIS IS NOT THE ONLY CONCERN THIS FORECAST. FRIDAY
NIGHT WILL BE MILD WITH TEMPERATURES REMAINING UP. IN
FACT...LOCATIONS ACROSS THE NORTH THAT DO NOT GET INTO THE SUNSHINE
WILL SLOWLY RISE INTO THE EVENING HOURS AND WILL REACH THEIR HIGH
TEMPERATURES IN THE LATE EVENING TO AROUND MIDNIGHT. THE STRONG
COLD FRONT COMES THROUGH EARLY SATURDAY MORNING AND TEMPERATURES
BEGIN TO FALL...WITH ONLY MINIMAL DIURNAL RISE IN THE AFTERNOON.
SATURDAY NIGHT AND SUNDAY THERE IS A WEAK SHORTWAVE THAT MOVES ALONG
A BAROCLINIC ZONE DRAPED FROM TEXAS UP THE OHIO RIVER VALLEY..WHICH
SHOULD PRODUCE A NICE BAND OF SNOW FOR AREAS NORTHWEST OF THE LOW
TRACK. THE TRICK IS WHETHER THIS SYSTEM WILL SHIFT FAR ENOUGH
NORTHWEST TO BRING SOME ACCUMULATING SNOWS TO THE FORECAST AREA
SATURDAY NIGHT AND EARLY SUNDAY. FOR NOW IT APPEARS THAT THE
SOUTHEAST PORTIONS OF THE AREA WILL GET SOME LIGHT SNOW
ACCUMULATIONS...BUT THE NORTHWEST EDGE OF THIS SNOW BAND WILL BE
FAIRLY SHARP...AND THE QUAD CITIES IS PROBABLY ONLY LOOKING SOME
PRETTY MINOR ACCUMULATIONS...DUSTING TO A HALF INCH PERHAPS.
BEHIND THIS SYSTEM WE ARE LOOKING AT GETTING SOME VERY COLD
TEMPERATURES INTO THE AREA...WITH 850MB TEMPS DROPPING TO AROUND
-10C BY MONDAY MORNING. AS LONG AS WE CLEAR OFF...TEMPERATURES WILL
DROP INTO THE TEENS. TEMPERATURES SHOULD SLOWLY MODERATE INTO
WEDNESDAY. ANOTHER LONGWAVE TROUGH IS EXPECTED TO MOVE THROUGH THE
AREA WEDNESDAY...BUT IT IS TOO DRY TO BRING MORE THAN A FRESH SHOT
OF COLDER AIR FOR THURSDAY.
LE
&&
.AVIATION...
VSBYS AND CIGS HAVE COLLAPSED A LITTLE SOONER THAN FORECAST AT
KBRL. A SIMILAR SITUATION WILL OCCUR OVER THE NEXT SEVERAL HOURS
AT KCID/KMLI/KDBQ. LIFR TO VLIFR CONDITIONS WILL BE OCCUR AFT
00Z/11. THE PROBABILITY OF BELOW MINIMUM CONDITIONS AT KCID/KDBQ
HAS INCREASED FROM SEVERAL HOURS AGO. DENSE FOG WITH POTENTIAL
ZERO/ZERO CONDITIONS IS NOW A THREAT FOR KCID/KDBQ. ..08..
&&
.CLIMATE...
CORRECTED THESE RECORD HIGHS.
RECORD HIGHS FOR JANUARY 11...
MOLINE.........56 IN 2012
CEDAR RAPIDS...53 IN 2012
DUBUQUE........52 IN 2012
BURLINGTON.....55 IN 2012
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...DENSE FOG ADVISORY FROM 2 AM TO 10 AM CST FRIDAY FOR BENTON-
BUCHANAN-DELAWARE-DUBUQUE-IOWA-JACKSON-JOHNSON-JONES-LINN.
IL...DENSE FOG ADVISORY FROM 2 AM TO 10 AM CST FRIDAY FOR CARROLL-JO
DAVIESS-STEPHENSON.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1221 PM CST THU JAN 10 2013
.UPDATE...
THE DRY AIR IS STILL WINNING FOR NOW. HOWEVER...BASED ON SFC OBS
AND IMPLIED RADAR THE LEADING EDGE OF PRECIPITATION REACHING THE
GROUND APPEARS TO BE ALIGNED WITH CONDENSATION PRESSURE DEFICITS
BELOW 50 IN THE 1000-850MB LAYER AND PWAT OF 1.10 PER RAP TRENDS.
ASSUMING THAT THIS TREND WILL CONTINUE...THEN THE LEADING EDGE OF
THE PRECIPITATION WOULD BE NO FURTHER NORTH THAN THE HWY 30
CORRIDOR BY MID AFTERNOON. THE RAP TRENDS HAVE BEEN FAIRLY
CONSISTENT IN INDICATING THAT A SIGNIFICANT SURGE OF MOISTURE FROM
MID TO LATE AFTERNOON WILL RESULT IN RAPID TOP DOWN SATURATION
WITH PRECIPITATION OCCURRING ACROSS THE ENTIRE CWFA BY THE EVENING
COMMUTE. AN UPDATE REFLECTING THESE TRENDS WILL BE AVAILABLE
SHORTLY. ..08..
&&
.PREV DISCUSSION... /ISSUED 1135 AM CST THU JAN 10 2013/
AVIATION...
THE INITIALLY DRY ATMOSPHERE WILL SATURATE THROUGH 00Z/11 ALLOWING
PRECIPITATION TO DEVELOP. THIS SATURATION WILL RESULT IN VFR
CONDITIONS RAPIDLY DETERIORATING TO IFR WITH LIFR OR VLIFR
CONDITIONS DVLPG AFT 00Z/11. THE MOISTURE SURGING INTO THE AREA
OVER A SNOW FIELD DOES BRING THE POSSIBILITY OF BELOW MINIMUMS
DEVELOPING AT KCID/KDBQ. AN INVERSION IS EXPECTED TO TRAP MOISTURE
FOR MUCH OF THE DAYLIGHT HOURS AFT 12Z/11 WHICH SHOULD RESULT IN
LIFR CONDITIONS CONTINUING. ..08..
PREV DISCUSSION... /ISSUED 957 AM CST THU JAN 10 2013/
UPDATE...
AN UPDATE HAS BEEN DONE TO REFLECT CURRENT TRENDS.
12Z SOUNDING SHOWS THE DRY AIR OVER THE AREA IS CONSIDERABLE. SAID
DRY AIR IS HAVING THE EXPECTED IMPACT ON PRECIPITATION GENERATION
AND OVERALL TIMING INTO THE AREA. WHERE IT IS RAINING ON THE
LEADING EDGE IT IS FALLING OUT OF MID LEVEL CLOUDS AROUND 10KFT
AGL AND IS LIKELY MORE SPRINKLES THAN RAIN.
TOP DOWN SATURATION IS NON-LINEAR BY NATURE AND NOT HANDLED BY THE
MODELS. EACH SITUATION IS DIFFERENT AND THE SATURATION CAN OCCUR
FASTER/SLOWER THAN EXPECTED.
A COMBINATION OF RAP TRENDS USING CONDENSATION PRESSURE
DEFICITS/FORCING ALONG WITH THE HEAVY RAIN TOOL SUGGEST SPRINKLES
OR VERY LIGHT RAIN MAY REACH A KGGI TO KGBG LINE BY MID DAY WITH
THE BETTER RAIN JUST GETTING INTO THE EXTREME SOUTH.
DURING THE AFTERNOON HOURS A MORE SIGNIFICANT SLUG OF MOISTURE
BEGINS MOVING TOWARD THE AREA.
BY MID AFTERNOON SPRINKLES OR VERY LIGHT RAIN SHOULD BE AS FAR
NORTH AS A KALO/KOLZ TO ROUGHLY KRPJ LINE. THE IMMEDIATE HWY 20
CORRIDOR FROM DUBUQUE EAST SHOULD STILL BE DRY BUT WITH RAIN
ENCROACHING ON THE AREA.
IF THE RAP TRENDS ARE CORRECT...SATURATION IS RAPIDLY ACHIEVED
ACROSS THE NORTHERN CWFA DURING THE LATE AFTERNOON HOURS. RAIN
SHOULD BE FALLING ACROSS THE ENTIRE AREA DURING THE EVENING COMMUTE.
THE DRY AIR WILL ALSO RESULT IN EVAPORATIVE COOLING WHICH MAY
SUPPRESS TEMPERATURES DURING THE DAY. LIKE YESTERDAY...THE HIGH
FOR THE VERIFYING PERIOD WILL LIKELY OCCUR IN THE 6-8 PM TIME
FRAME. THE HIGH FOR THE CLIMATE DAY OF JAN 10TH WILL LIKELY OCCUR
BETWEEN 8 PM AND MIDNIGHT. ..08..
PREV DISCUSSION... /ISSUED 337 AM CST THU JAN 10 2013/
SYNOPSIS...
CLOSED UPPER LOW WAS LOCATED OVER WEST TX AND HAS RECENTLY BEGUN
LIFTING NORTH IN RESPONSE TO ENERGY MOVING ONSHORE WEST COAST.
RAIN SHIELD ATTENDANT TO TX LOW ALSO LIFTING NORTH WITH TWO MAIN
AREAS... ONE OVER KS/OK/NW TX JUST NORTH OF MAIN CIRCULATION IN
ZONE OF STRONG ELEVATED MOISTURE TRANSPORT... AND THE OTHER MORE
LINEAR EXTENDING FROM TX/LA GULF COAST TO JUST S/E OF ST LOUIS
IN A SECONDARY BRANCH OF MOISTURE ADVECTION AND INCREASINGLY
DIFFLUENT FLOW ALOFT. 00Z RAOBS TO OUR SOUTH SHOW SIGNIFICANT
AMOUNTS OF MOISTURE WITH PRECIPITABLE WATER VALUES AT KOUN...
KLZK...KFWD AND KJAN RANGING FROM NEARLY 1.25 INCHES TO 1.4 INCHES
WHICH IS AROUND 250 TO NEARLY 350 PERCENT OF NORMAL.
SHORT TERM...TODAY AND TONIGHT...
MAIN FOCUS WITH INCOMING RAIN AND AMOUNTS... AND TEMPS. SHORT RANGE
MODELS IN PRETTY GOOD AGREEMENT ON CLOSED TX LOW LIFTING NEGATIVELY
TILTED THROUGH THE MID MISSISSIPPI VALLEY TONIGHT...PASSING NEAR TO
JUST SOUTH OF CWA. RAIN WILL OVERSPREAD THE CWA FROM SOUTH TO NORTH
TODAY AND INITIALLY BE MAINLY LIGHT. RAIN INTENSITY TO INCREASE
LATER TODAY (MAINLY SOUTH) AND ESPECIALLY THIS EVE TO JUST BEYOND
06Z WITH MAIN BOUT OF FORCING. BY THIS TIME... SIGNIFICANT MOISTURE
WILL BE IN PLACE WITH GEFS DEPICTING PRECIPITABLE WATER VALUES AT
LEAST 4 TO 5 STANDARD DEVIATIONS ABOVE NORMAL AND GENERALLY RANGING
FROM 1 TO 1.25 INCHES. THUS... SYSTEM WILL BE VERY WET WITH
WIDESPREAD 0.3 TO 0.75 INCH RAIN AMOUNTS THROUGH 12Z... WITH SOME
AREAS OF 1-1.5 INCHES ESPECIALLY JUST NW OF MAIN CENTER OF CIRCULATION
WITH ALONG AND S/E OF KIOW-KFEP LINE MOST LIKELY PORTION OF CWA TO
SEE SOME OF THESE HIGHER AMOUNTS FROM THE LOOKS OF THINGS ATTIM.
RAIN TAPER OFF IN INTENSITY AND AMOUNTS OVERNIGHT BUT ABUNDANT LOW
LEVEL MOISTURE AND LIFT SUPPORTIVE OF LIGHT RAIN AND DRIZZLE. SOME
AREAS OF FOG ALSO LIKELY TONIGHT AS SFC LOW MOVES ACROSS THE CWA.
AS FOR TEMPS... MANY AREAS LIKELY WILL SEE DAILY HIGHS OCCUR LATER
THIS EVE AS TEMPS CONTINUE TO CLIMB THROUGH ADVECTIVE PROCESSES.
WITH E/SE WINDS... CLOUDS AND RAIN OVERSPREADING AREA TODAY I STAYED
TOWARD THE COOLER SIDE OF GUIDANCE FOR TEMPS. I ALLOWED FOR A LITTLE
DROP OFF EARLY THIS EVE BEFORE TEMPS RISE. MCCLURE
LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY...
WARM SECTOR OF THE SURFACE CYCLONE PASSING WELL TO THE NORTHWEST
WILL SWEEP THROUGH THE AREA FRIDAY...RESULTING IN A POTENTIAL FOR
RECORD HIGH TEMPERATURES. TRAILING COLD FRONT WILL BRING MUCH COLDER
WEATHER THAT WILL PREVAIL THROUGH WEEKEND INTO NEXT WEEK. AN UPPER
LEVEL SYSTEM IS STILL ON TRACK TO BRING THE POTENTIAL FOR LIGHT SNOW
ACROSS MAINLY THE SOUTHEAST SATURDAY NIGHT INTO EARLY SUNDAY.
CHALLENGE FOR FRIDAY WILL BE WHETHER THE DEVELOPING SOUTHERLY WINDS
AND WARM ADVECTION CAN BREAK THROUGH THE MOIST LOW LEVEL INVERSION
AND STRATUS UNDER THE STRONGER ELEVATED WARM ADVECTION AND INFLUX OF
MUCH DRIER AIR ABOVE 900 MB. MODEL FORECAST SOUNDINGS OFFER A WIDE
RANGE OF SOLUTIONS...WITH THE NAM MOST PESSIMISTIC SUGGESTING LOW CLOUDS
AND POSSIBLE FOG HANGING ON THROUGH THE DAY WITH MUCH COOLER
TEMPERATURES...LIKELY DUE TO THE MODEL/S OVERDONE DEPICTION OF
LINGERING SNOW COVER. FOR NOW...WILL GO WITH A COMPROMISE CLOSER TO
A BLEND OF GFS AND ECMWF LOW LEVEL THERMAL FIELDS. THIS WOULD RESULT
IN AT LEAST PARTIAL CLEARING OF STRATUS INTO THE FAR SOUTH DURING
THE AFTERNOON ON 10 TO 15 KT SOUTHERLY SURFACE WINDS. FURTHER
NORTH...THE STRATUS WILL TAKE LONGER TO CLEAR IN THE SLIGHTLY WEAKER
SOUTH WINDS OVER THE COLDER GROUND AND PATCHES OF SNOW. THIS IMPACT
WILL BE GREATEST NORTH OF THE HIGHWAY 30 CORRIDOR WHERE AT LEAST
PATCHES OF OLD SNOW AND ICE SHOULD REMAIN. WILL GO WITH A MENTION OF
FOG AND DRIZZLE THERE FOR MUCH OF THE DAY...WHILE ANY FOG/HAZE OVER
THE CENTRAL AND SOUTH SHOULD DROP BELOW THRESHOLDS FOR MENTION IN
THE PUBLIC FORECAST BY LATE MORNING. OVERALL CONFIDENCE REMAINS
BELOW AVERAGE IN THE POTENTIAL FOR CLEARING AND THE DEPTH OF
MIXING...OVER ESPECIALLY THE CENTRAL AND NORTH AND WILL KEEP HIGHS
LIMITED TO THE MID 40S TO AROUND 50 NORTH OF I-80...WHILE THE FAR
SOUTH HAS A GOOD POTENTIAL TO BREAKOUT AND WARM INTO THE MID AND
UPPER 50S. THIS MAY THREATEN RECORD HIGHS SET LAST YEAR...ESPECIALLY
AT BRL. THESE ARE LISTED IN THE CLIMATE SECTION BELOW.
WILL CONTINUE WITH SLIGHTLY FASTER TIMING SHOWN BY NON-GFS MODEL
CONSENSUS...SWEEPING THE COLD FRONT THROUGH THE FORECAST AREA
FRIDAY NIGHT AND EXITING TO THE EAST BY SUNRISE SATURDAY. THIS
WILL RESULT IN CONTINUED NON-DIURNAL TEMPERATURE TRENDS FRIDAY NIGHT
INTO SATURDAY...WHERE TEMPERATURES SHOULD START FROM THE 30S NW TO
UPPER 40S SE EARLY...DROPPING TO THE 20S AND 30S BY LATE SATURDAY
AFTERNOON WITH COLD ADVECTION ON BRISK WEST WINDS. WITH VERY LITTLE
LOW OR MID LEVEL MOISTURE...NO PRECIPITATION IS EXPECTED WITH THE
FROPA OR IN THE SUBSIDENCE THAT FOLLOWS SATURDAY.
SATURDAY NIGHT...THE UPPER TROUGH AXIS REMAINS WELL TO THE WEST
KEEPING A FAST SW FLOW ALOFT OVER THE AREA. AN EMBEDDED SHORTWAVE
AND RIGHT ENTRANCE REGION TO A STRONG UPPER JET MOVING THROUGH THE
UPPER GREAT LAKES WILL SEND A WAVE OF LIFT OVER THE SOUTHEAST THIRD
OF THE FORECAST AREA. WHILE MOISTURE WILL BE LIMITED...CHANCE POPS
FOR LIGHT SNOW ARE JUSTIFIED FOR ESPECIALLY W CENTRAL IL. THE GFS
AND ECMWF THERMAL FIELDS WOULD SUPPORT A POSSIBILITY FOR MIXED
PRECIPITATION AT THE ONSET...WHICH WILL BE LEFT FOR CONSIDERATION IN
LATER FORECASTS. OTHERWISE...COLD ADVECTION WILL CONTINUE
WITH TEMPERATURES DROPPING INTO THE TEENS BY SUNDAY MORNING OVER THE
AREA.
SUNDAY THROUGH WEDNESDAY...COLD HIGH PRESSURE WILL RESULT IN BELOW
NORMAL TEMPERATURES SUNDAY AND MONDAY. A DEVELOPING UPPER LOW OVER
THE HUDSON BAY REGION WILL THEN PLACE A CYCLONIC NW FLOW OVERHEAD
TUE THROUGH WED. THE ACTIVE STORM TRACK STAYING NORTH OF THE
AREA...ALONG WITH GRADUAL MODERATION OF TEMPERATURES
ALOFT...SUGGESTS A PERIOD OF DRY WEATHER WITH SLIGHTLY WARMER
TEMPERATURES BY MID WEEK.
SHEETS
CLIMATE...
RECORD HIGHS FOR JANUARY 11...
MOLINE.........56 IN 2012
CEDAR RAPIDS...53 IN 2012
DUBUQUE........52 IN 2012
BURLINGTON.....55 IN 2012
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1135 AM CST THU JAN 10 2013
.AVIATION...
THE INITIALLY DRY ATMOSPHERE WILL SATURATE THROUGH 00Z/11 ALLOWING
PRECIPITATION TO DEVELOP. THIS SATURATION WILL RESULT IN VFR
CONDITIONS RAPIDLY DETERIORATING TO IFR WITH LIFR OR VLIFR
CONDITIONS DVLPG AFT 00Z/11. THE MOISTURE SURGING INTO THE AREA
OVER A SNOW FIELD DOES BRING THE POSSIBILITY OF BELOW MINIMUMS
DEVELOPING AT KCID/KDBQ. AN INVERSION IS EXPECTED TO TRAP MOISTURE
FOR MUCH OF THE DAYLIGHT HOURS AFT 12Z/11 WHICH SHOULD RESULT IN
LIFR CONDITIONS CONTINUING. ..08..
&&
.PREV DISCUSSION... /ISSUED 957 AM CST THU JAN 10 2013/
UPDATE...
AN UPDATE HAS BEEN DONE TO REFLECT CURRENT TRENDS.
12Z SOUNDING SHOWS THE DRY AIR OVER THE AREA IS CONSIDERABLE. SAID
DRY AIR IS HAVING THE EXPECTED IMPACT ON PRECIPITATION GENERATION
AND OVERALL TIMING INTO THE AREA. WHERE IT IS RAINING ON THE
LEADING EDGE IT IS FALLING OUT OF MID LEVEL CLOUDS AROUND 10KFT
AGL AND IS LIKELY MORE SPRINKLES THAN RAIN.
TOP DOWN SATURATION IS NON-LINEAR BY NATURE AND NOT HANDLED BY THE
MODELS. EACH SITUATION IS DIFFERENT AND THE SATURATION CAN OCCUR
FASTER/SLOWER THAN EXPECTED.
A COMBINATION OF RAP TRENDS USING CONDENSATION PRESSURE
DEFICITS/FORCING ALONG WITH THE HEAVY RAIN TOOL SUGGEST SPRINKLES
OR VERY LIGHT RAIN MAY REACH A KGGI TO KGBG LINE BY MID DAY WITH
THE BETTER RAIN JUST GETTING INTO THE EXTREME SOUTH.
DURING THE AFTERNOON HOURS A MORE SIGNIFICANT SLUG OF MOISTURE
BEGINS MOVING TOWARD THE AREA.
BY MID AFTERNOON SPRINKLES OR VERY LIGHT RAIN SHOULD BE AS FAR
NORTH AS A KALO/KOLZ TO ROUGHLY KRPJ LINE. THE IMMEDIATE HWY 20
CORRIDOR FROM DUBUQUE EAST SHOULD STILL BE DRY BUT WITH RAIN
ENCROACHING ON THE AREA.
IF THE RAP TRENDS ARE CORRECT...SATURATION IS RAPIDLY ACHIEVED
ACROSS THE NORTHERN CWFA DURING THE LATE AFTERNOON HOURS. RAIN
SHOULD BE FALLING ACROSS THE ENTIRE AREA DURING THE EVENING COMMUTE.
THE DRY AIR WILL ALSO RESULT IN EVAPORATIVE COOLING WHICH MAY
SUPPRESS TEMPERATURES DURING THE DAY. LIKE YESTERDAY...THE HIGH
FOR THE VERIFYING PERIOD WILL LIKELY OCCUR IN THE 6-8 PM TIME
FRAME. THE HIGH FOR THE CLIMATE DAY OF JAN 10TH WILL LIKELY OCCUR
BETWEEN 8 PM AND MIDNIGHT. ..08..
PREV DISCUSSION... /ISSUED 337 AM CST THU JAN 10 2013/
SYNOPSIS...
CLOSED UPPER LOW WAS LOCATED OVER WEST TX AND HAS RECENTLY BEGUN
LIFTING NORTH IN RESPONSE TO ENERGY MOVING ONSHORE WEST COAST.
RAIN SHIELD ATTENDANT TO TX LOW ALSO LIFTING NORTH WITH TWO MAIN
AREAS... ONE OVER KS/OK/NW TX JUST NORTH OF MAIN CIRCULATION IN
ZONE OF STRONG ELEVATED MOISTURE TRANSPORT... AND THE OTHER MORE
LINEAR EXTENDING FROM TX/LA GULF COAST TO JUST S/E OF ST LOUIS
IN A SECONDARY BRANCH OF MOISTURE ADVECTION AND INCREASINGLY
DIFFLUENT FLOW ALOFT. 00Z RAOBS TO OUR SOUTH SHOW SIGNIFICANT
AMOUNTS OF MOISTURE WITH PRECIPITABLE WATER VALUES AT KOUN...
KLZK...KFWD AND KJAN RANGING FROM NEARLY 1.25 INCHES TO 1.4 INCHES
WHICH IS AROUND 250 TO NEARLY 350 PERCENT OF NORMAL.
SHORT TERM...TODAY AND TONIGHT...
MAIN FOCUS WITH INCOMING RAIN AND AMOUNTS... AND TEMPS. SHORT RANGE
MODELS IN PRETTY GOOD AGREEMENT ON CLOSED TX LOW LIFTING NEGATIVELY
TILTED THROUGH THE MID MISSISSIPPI VALLEY TONIGHT...PASSING NEAR TO
JUST SOUTH OF CWA. RAIN WILL OVERSPREAD THE CWA FROM SOUTH TO NORTH
TODAY AND INITIALLY BE MAINLY LIGHT. RAIN INTENSITY TO INCREASE
LATER TODAY (MAINLY SOUTH) AND ESPECIALLY THIS EVE TO JUST BEYOND
06Z WITH MAIN BOUT OF FORCING. BY THIS TIME... SIGNIFICANT MOISTURE
WILL BE IN PLACE WITH GEFS DEPICTING PRECIPITABLE WATER VALUES AT
LEAST 4 TO 5 STANDARD DEVIATIONS ABOVE NORMAL AND GENERALLY RANGING
FROM 1 TO 1.25 INCHES. THUS... SYSTEM WILL BE VERY WET WITH
WIDESPREAD 0.3 TO 0.75 INCH RAIN AMOUNTS THROUGH 12Z... WITH SOME
AREAS OF 1-1.5 INCHES ESPECIALLY JUST NW OF MAIN CENTER OF CIRCULATION
WITH ALONG AND S/E OF KIOW-KFEP LINE MOST LIKELY PORTION OF CWA TO
SEE SOME OF THESE HIGHER AMOUNTS FROM THE LOOKS OF THINGS ATTIM.
RAIN TAPER OFF IN INTENSITY AND AMOUNTS OVERNIGHT BUT ABUNDANT LOW
LEVEL MOISTURE AND LIFT SUPPORTIVE OF LIGHT RAIN AND DRIZZLE. SOME
AREAS OF FOG ALSO LIKELY TONIGHT AS SFC LOW MOVES ACROSS THE CWA.
AS FOR TEMPS... MANY AREAS LIKELY WILL SEE DAILY HIGHS OCCUR LATER
THIS EVE AS TEMPS CONTINUE TO CLIMB THROUGH ADVECTIVE PROCESSES.
WITH E/SE WINDS... CLOUDS AND RAIN OVERSPREADING AREA TODAY I STAYED
TOWARD THE COOLER SIDE OF GUIDANCE FOR TEMPS. I ALLOWED FOR A LITTLE
DROP OFF EARLY THIS EVE BEFORE TEMPS RISE. MCCLURE
LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY...
WARM SECTOR OF THE SURFACE CYCLONE PASSING WELL TO THE NORTHWEST
WILL SWEEP THROUGH THE AREA FRIDAY...RESULTING IN A POTENTIAL FOR
RECORD HIGH TEMPERATURES. TRAILING COLD FRONT WILL BRING MUCH COLDER
WEATHER THAT WILL PREVAIL THROUGH WEEKEND INTO NEXT WEEK. AN UPPER
LEVEL SYSTEM IS STILL ON TRACK TO BRING THE POTENTIAL FOR LIGHT SNOW
ACROSS MAINLY THE SOUTHEAST SATURDAY NIGHT INTO EARLY SUNDAY.
CHALLENGE FOR FRIDAY WILL BE WHETHER THE DEVELOPING SOUTHERLY WINDS
AND WARM ADVECTION CAN BREAK THROUGH THE MOIST LOW LEVEL INVERSION
AND STRATUS UNDER THE STRONGER ELEVATED WARM ADVECTION AND INFLUX OF
MUCH DRIER AIR ABOVE 900 MB. MODEL FORECAST SOUNDINGS OFFER A WIDE
RANGE OF SOLUTIONS...WITH THE NAM MOST PESSIMISTIC SUGGESTING LOW CLOUDS
AND POSSIBLE FOG HANGING ON THROUGH THE DAY WITH MUCH COOLER
TEMPERATURES...LIKELY DUE TO THE MODEL/S OVERDONE DEPICTION OF
LINGERING SNOW COVER. FOR NOW...WILL GO WITH A COMPROMISE CLOSER TO
A BLEND OF GFS AND ECMWF LOW LEVEL THERMAL FIELDS. THIS WOULD RESULT
IN AT LEAST PARTIAL CLEARING OF STRATUS INTO THE FAR SOUTH DURING
THE AFTERNOON ON 10 TO 15 KT SOUTHERLY SURFACE WINDS. FURTHER
NORTH...THE STRATUS WILL TAKE LONGER TO CLEAR IN THE SLIGHTLY WEAKER
SOUTH WINDS OVER THE COLDER GROUND AND PATCHES OF SNOW. THIS IMPACT
WILL BE GREATEST NORTH OF THE HIGHWAY 30 CORRIDOR WHERE AT LEAST
PATCHES OF OLD SNOW AND ICE SHOULD REMAIN. WILL GO WITH A MENTION OF
FOG AND DRIZZLE THERE FOR MUCH OF THE DAY...WHILE ANY FOG/HAZE OVER
THE CENTRAL AND SOUTH SHOULD DROP BELOW THRESHOLDS FOR MENTION IN
THE PUBLIC FORECAST BY LATE MORNING. OVERALL CONFIDENCE REMAINS
BELOW AVERAGE IN THE POTENTIAL FOR CLEARING AND THE DEPTH OF
MIXING...OVER ESPECIALLY THE CENTRAL AND NORTH AND WILL KEEP HIGHS
LIMITED TO THE MID 40S TO AROUND 50 NORTH OF I-80...WHILE THE FAR
SOUTH HAS A GOOD POTENTIAL TO BREAKOUT AND WARM INTO THE MID AND
UPPER 50S. THIS MAY THREATEN RECORD HIGHS SET LAST YEAR...ESPECIALLY
AT BRL. THESE ARE LISTED IN THE CLIMATE SECTION BELOW.
WILL CONTINUE WITH SLIGHTLY FASTER TIMING SHOWN BY NON-GFS MODEL
CONSENSUS...SWEEPING THE COLD FRONT THROUGH THE FORECAST AREA
FRIDAY NIGHT AND EXITING TO THE EAST BY SUNRISE SATURDAY. THIS
WILL RESULT IN CONTINUED NON-DIURNAL TEMPERATURE TRENDS FRIDAY NIGHT
INTO SATURDAY...WHERE TEMPERATURES SHOULD START FROM THE 30S NW TO
UPPER 40S SE EARLY...DROPPING TO THE 20S AND 30S BY LATE SATURDAY
AFTERNOON WITH COLD ADVECTION ON BRISK WEST WINDS. WITH VERY LITTLE
LOW OR MID LEVEL MOISTURE...NO PRECIPITATION IS EXPECTED WITH THE
FROPA OR IN THE SUBSIDENCE THAT FOLLOWS SATURDAY.
SATURDAY NIGHT...THE UPPER TROUGH AXIS REMAINS WELL TO THE WEST
KEEPING A FAST SW FLOW ALOFT OVER THE AREA. AN EMBEDDED SHORTWAVE
AND RIGHT ENTRANCE REGION TO A STRONG UPPER JET MOVING THROUGH THE
UPPER GREAT LAKES WILL SEND A WAVE OF LIFT OVER THE SOUTHEAST THIRD
OF THE FORECAST AREA. WHILE MOISTURE WILL BE LIMITED...CHANCE POPS
FOR LIGHT SNOW ARE JUSTIFIED FOR ESPECIALLY W CENTRAL IL. THE GFS
AND ECMWF THERMAL FIELDS WOULD SUPPORT A POSSIBILITY FOR MIXED
PRECIPITATION AT THE ONSET...WHICH WILL BE LEFT FOR CONSIDERATION IN
LATER FORECASTS. OTHERWISE...COLD ADVECTION WILL CONTINUE
WITH TEMPERATURES DROPPING INTO THE TEENS BY SUNDAY MORNING OVER THE
AREA.
SUNDAY THROUGH WEDNESDAY...COLD HIGH PRESSURE WILL RESULT IN BELOW
NORMAL TEMPERATURES SUNDAY AND MONDAY. A DEVELOPING UPPER LOW OVER
THE HUDSON BAY REGION WILL THEN PLACE A CYCLONIC NW FLOW OVERHEAD
TUE THROUGH WED. THE ACTIVE STORM TRACK STAYING NORTH OF THE
AREA...ALONG WITH GRADUAL MODERATION OF TEMPERATURES
ALOFT...SUGGESTS A PERIOD OF DRY WEATHER WITH SLIGHTLY WARMER
TEMPERATURES BY MID WEEK.
SHEETS
CLIMATE...
RECORD HIGHS FOR JANUARY 11...
MOLINE.........56 IN 2012
CEDAR RAPIDS...53 IN 2012
DUBUQUE........52 IN 2012
BURLINGTON.....55 IN 2012
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORMAN OK
108 PM CST THU JAN 10 2013
.UPDATE...
UPDATED AGAIN AS SHOWERS CONTINUE TO FORM NEAR THE CIRCULATION
CENTER. RAP AND LOCAL WRF SHOW THAT THESE SHOWERS WILL PERSIST
THIS AFTERNOON AND LIFT NORTH/NORTHEAST. HAVE INCREASED POPS
SIGNIFICANTLY AND GONE WITH AREAL WORDING NEAR AND NORTH/NORTHEAST
OF CURRENT DEVELOPMENT.
&&
.PREV DISCUSSION... /ISSUED 1242 PM CST THU JAN 10 2013/
UPDATE...
UPDATING THE PACKAGE TO REMOVE SOME OF THE TEMPORAL WORDING AND
TO ACCOUNT FOR CURRENT TRENDS IN PRECIPITATION AND CLOUDS. THE
MAIN BAND OF PRECIPITATION HAD MOVED OUT OF THE AREA... ALTHOUGH
SOME DRIZZLE AND/OR LIGHT RAIN HAS REDEVELOPED NEAR THE UPPER
LOW. SOME DRIER AIR IS ALSO ENTRAINING INTO THE CIRCULATION AND
ALLOWING SOME PARTIAL CLEARING FROM SOUTHEAST INTO CENTRAL
OKLAHOMA.
PREV DISCUSSION... /ISSUED 1139 AM CST THU JAN 10 2013/
AVIATION...
IFR TO BRIEF LIFR DUE TO LOW CIGS AND FOG WILL CONTINUE OVER MANY
OF THE TERMINALS THROUGH THE EARLY AFTERNOON HOURS. CONDITIONS
WILL SLOWLY IMPROVE LATER THIS AFTERNOON AND EARLY THIS
EVENING...BUT SOME TEMPORARY FOG MAY RETURN AROUND 04-07Z LATE
TONIGHT. FLIGHT CONDITIONS WILL IMPROVE AFTER THIS WITH VFR LIKELY
RETURNING TO MOST OF THE TERMINALS BEFORE SUNRISE.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 56 43 66 39 / 50 10 10 10
HOBART OK 53 39 65 34 / 30 10 10 10
WICHITA FALLS TX 59 43 71 38 / 20 10 10 10
GAGE OK 50 38 62 24 / 20 10 10 10
PONCA CITY OK 56 42 67 29 / 30 10 10 10
DURANT OK 61 45 68 50 / 20 10 10 20
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
99/99
AREA FORECAST DISCUSSION
NWS MEDFORD OR
857 AM PST THU JAN 10 2013
.DISCUSSION...CURRENT WATER VAPOR IMAGE SHOWS ANOTHER DISTURBANCE
MOVING TOWARDS THE FORECAST AREA. THIS COULD BE SIGNIFICANT ENOUGH
TO BRING A FEW MODERATE TO HEAVY SHOWERS TO THE AREA THIS MORNING
THROUGH LATE THIS AFTERNOON. SNOW LEVELS WILL AVERAGE AROUND 1500
FEET THIS AFTERNOON...BUT COULD TEMPORALLY LOWER BETWEEN 500 AND
1000 FEET IN LOCATIONS THAT GET CAUGHT UNDER HEAVIER SHOWERS
RESULTING IN TEMPORARY ACCUMULATION OF A TRACE TO HALF INCH IN
THE VALLEYS AND 1 TO 3 INCHES ABOVE 2000 FEET. THIS IS BEING
SUPPORTED BY THE FACT THAT WEBCAMS IN REEDSPORT AND A FEW OTHER
LOCATIONS BELOW 1000 FEET ARE SHOWING MODERATE SNOWFALL WITH SNOW
ACCUMULATING ON GRASSY AREAS AND ROADS.
CURRENT WINTER WEATHER ADVISORIES WEST OF THE CASCADES END AT 1
PM PST AND WE`LL TAKE A CLOSER LOOK AND SEE IF THE ENDING TIME
NEEDS TO BE EXTENDED LATER. -PETRUCELLI
&&
.AVIATION...AVIATION...A VERY COLD AND SHOWERY AIR MASS WILL PERSIST
WITH A SERIES OF DISTURBANCES THROUGH FRIDAY. THIS WILL RESULT IN
PERIODS OF SNOW SHOWERS...MOST NUMEROUS IN SOUTHWEST OREGON.
THUNDERSTORMS ARE POSSIBLE ALONG THE COAST TONIGHT INTO THIS
MORNING. ADDITIONALLY...FREQUENT MOUNTAIN OBSCURATIONS WITH
VISIBILITY REDUCED IN SNOW SHOWERS CAN BE EXPECTED THROUGH TODAY.
SKY CONDITION TODAY WILL BE VARIABLE DUE TO THE SHOWERY NATURE OF
THE WEATHER...INCLUDING IFR DURING MORE INTENSE SNOW SHOWERS BUT
PREDOMINANTLY MVFR CEILINGS. SNOW SHOWERS WILL BE MORE NUMEROUS AT
NORTHWEST FACING SLOPES SUCH AS PARTS OF THE UMPQUA DIVIDE AND
SISKIYOU SUMMIT. THE FREEZING LEVEL WILL REMAIN BETWEEN 1000 AND
2000 FT MSL THROUGH FRIDAY.
&&
.PREV DISCUSSION... /ISSUED 348 AM PST THU JAN 10 2013/
SHORT TERM...AN UPPER TROUGH WILL REMAIN OVER THE REGION TODAY
WHILE A COUPLE SHORTWAVES MOVE THROUGH THE AREA BRINGING SCATTERED
TO WIDESPREAD SHOWERS INTO THE AREA. THE UPPER TROUGH GRADUALLY
SHIFTS EASTWARD TONIGHT AND FRIDAY WITH A RIDGE OFFSHORE NUDGING
INTO THE AREA FRIDAY AND SATURDAY. HOWEVER ADDITIONAL SHORTWAVE
DISTURBANCES WILL BRING THE POTENTIAL FOR MORE PRECIPITATION
THROUGH SATURDAY NIGHT.
A LARGE BATCH OF SHOWERS IS VISIBLE ON SATELLITE AND MOVING INTO
WESTERN PORTIONS OF THE AREA THIS MORNING. SNOW LEVELS ARE AROUND
1000 FEET THIS MORNING. LIGHT ACCUMULATIONS IN SHOWERS ARE
EXPECTED IN WEST SIDE VALLEYS AS WELL AS THE MOUNTAINS THIS
MORNING. ALSO A SECOND SHORTWAVE IS VISIBLE JUST OFF ASTORIA AND IS
EXPECTED TO MOVE INTO NORTHERN PORTIONS OF THE CWA IN THE MID TO
LATE MORNING.
THE RUC MODEL SEEMS TO HAVE THE BEST HANDLE ON THE TRACK OF THE
SHORTWAVES AND PRECIPITATION. IT SHOWS SHOWERS INCREASING EARLY
THIS MORNING FROM THE CASCADES WEST. THE SECOND SHORTWAVE HAS A
WEAK SURFACE LOW ASSOCIATED WITH IT. THIS LOW IS FORECAST TO TRACK
SOUTH-SOUTHEAST MOVING INLAND AND INTO DOUGLAS COUNTY IN THE LATE
MORNING...THEN TRACKING EAST OF THE CASCADES IN THE AFTERNOON. AS
THIS FEATURE MOVES INLAND...EXPECT ADDITIONAL SHOWERS FROM THE
CASCADES WEST TO CONTINUE INTO THE AFTERNOON AS WELL AS SHOWERS
INCREASING EAST OF THE CASCADES DURING THE AFTERNOON. HAVE
EXTENDED THE WINTER WEATHER ADVISORIES THROUGH NOON DUE TO THE
EXPECTED CONTINUATION OF SHOWERS WITH THIS SECOND DISTURBANCE.
ALTHOUGH SHOWERS WILL CONTINUE THROUGH THE AFTERNOON...SNOW LEVELS
WILL RISE SLIGHTLY AND DAYTIME WARMING IS EXPECTED TO ALLOW LITTLE
ADDITIONAL SNOW IN THE VALLEYS. HIGHER TERRAIN WILL CONTINUE TO
SEE LIGHT ADDITIONAL SNOW ACCUMULATIONS THOUGH. THE RUC MODEL
INDICATES A POTENTIAL FOR SOME LIGHT TO MODERATE SNOW
ACCUMULATIONS OVER THE SOUTHERN OREGON CASCADES AND INTO NORTHERN
KLAMATH COUNTY. IF SNOW SHOWERS BECOME WIDESPREAD...MAY NEED TO ADD
OR EXTEND THE WINTER WEATHER ADVISORIES FOR THESE AREAS.
CURRENTLY...CONFIDENCE IN LOW IN THE HOW WIDESPREAD AND HEAVY
AFTERNOON SHOWERS WILL BE.
AREAS OF LIGHT SHOWERS ARE EXPECTED TO LINGER IN TO THE EVENING. OF
NOTE IS THE RUC SHOWS SHOWERS DECREASING FROM NORTH TO SOUTH OVER
THE AREA DURING THE EVENING.
THE UPPER TROUGH GRADUALLY SHIFTS EAST THURSDAY NIGHT AND FRIDAY.
HOWEVER ADDITIONAL DISTURBANCES ON THE BACKSIDE OF THE TROUGH ARE
FORECAST TO BRING ADDITIONAL LIGHT SHOWERS...ESPECIALLY FROM THE
CASCADES WEST THURSDAY NIGHT AND FRIDAY. THEN MODELS SHOW A
BRIEF BREAK IN THE PATTERN FRIDAY EVENING AS A RIDGE OFFSHORE
NUDGES INTO THE PACNW COAST.
ON SATURDAY...MODELS HAVE SHOWN VARIABILITY WITH A COUPLE SHORTWAVES
MOVING DOWN FROM THE NORTH AROUND THE RIDGE. THE GFS AND NAM ARE
STRONGER WITH THESE DISTURBANCES THAN THE ECMWF...ESPECIALLY WITH
THE SECOND SHORTWAVE SATURDAY EVENING AND NIGHT. BEHIND THESE
DISTURBANCES EXPECT NORTHERLY FLOW TO BRING VERY COLD TEMPERATURES
SUNDAY MORNING...ESPECIALLY EAST OF THE CASCADES. COLD
TEMPERATURES ARE FORECAST TO CONTINUE INTO MONDAY.
PREV EXTENDED DISCUSSION... /ISSUED 245 PM PST WED JAN 9 2013/
EXTENDED TERM...SUNDAY MORNING THROUGH WEDNESDAY NIGHT...
THE LONG TERM FORECAST IS RATHER QUIET...ONCE THE WEEKEND SYSTEM
MAKES ITS EXIT OUT OF THE AREA. THE SHORTWAVE THAT IS EXPECTED TO
TRAVERSE THE NORTHERLY FLOW OVER THE REGION SATURDAY NIGHT AND
SUNDAY MORNING WILL EXIT TO THE SOUTH BY SUNDAY NIGHT...AND WITH IT
SO WILL PRECIPITATION CHANCES. WHAT PRECIPITATION THAT DOES FALL
DURING THE DAY SUNDAY WILL BE RELATIVELY LIGHT...AND WITH SNOW
LEVELS REMAINING ABOVE 2500 TO 3000 FEET...ANY IMPACTS WILL BE
CONFINED TO HIGHER ELEVATIONS.
ONCE THE SHORTWAVE FULLY EXITS THE AREA...HIGH AMPLITUDE TOWARDS THE
WEST COAST. THIS WILL PLACE THE FORECAST AREA UNDER THE EASTERN
PERIPHERY OF THE RIDGE AND UNDER NORTHERLY FLOW...BUT THE MAIN BELT
OF WESTERLIES WILL KEEP ANY SHORTWAVES WELL TO THE EAST THROUGHOUT
THE REST OF THE TERM. WITH THE CLEARER SKIES...THE USUAL SUSPECTS
WILL ARISE. THE FIRST IS THE THERMAL TROUGH...WHICH WILL PRODUCE
GUSTY WINDS ALONG RIDGE LINES ABOVE 5000 FEET. THE SECOND WILL BE
PERSISTENT MORNING FOG IN THE VALLEYS. LOW TEMPERATURES WILL STILL
HOVER AT OR BELOW FREEZING WITHIN MANY OF THE VALLEYS...SO FREEZING
FOG MAY BECOME AN ISSUE...AS ROADS AND OTHER SURFACES COULD BECOME
SLICK. OTHERWISE...EXPECT CLEARER SKIES...WITH TEMPERATURES RISING
TO NEAR OR EVEN SLIGHTLY ABOVE SEASONAL NORMALS BY MIDWEEK. -BPN
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR ORZ027-028.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY ABOVE 1000 FEET FOR
FOR ORZ021-022.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY ABOVE 1000 FEET FOR
FOR ORZ023.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR ORZ025.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR ORZ024-026.
CA...WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR CAZ081>083.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY ABOVE 1500 FEET FOR
FOR CAZ080.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS FROM 1 PM THIS AFTERNOON TO 7 AM
PST FRIDAY FOR PZZ350-356.
HAZARDOUS SEAS WARNING FROM 1 PM THIS AFTERNOON TO 4 AM PST
FRIDAY FOR PZZ350-356.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 PM PST THIS
AFTERNOON FOR PZZ350-356.
SMALL CRAFT ADVISORY FOR WINDS UNTIL 7 AM PST FRIDAY FOR
PZZ370-376.
HAZARDOUS SEAS WARNING UNTIL 4 AM PST FRIDAY FOR PZZ370-376.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 AM PST THIS
MORNING FOR PZZ370-376.
$$
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1035 AM CST THU JAN 10 2013
.UPDATE...
HAVE PUSHED BACK PRECIP CHANCES UNTIL 21Z IN THE FAR
SOUTHWEST...AND ABOUT 23Z IN MILWAUKEE AND MADISON. THE
NAM12...GEM...SREF...CRAS SHOW LITTLE TO NO PRECIPITATION BEFORE
21Z. THE HRRR EVEN KEEPS THE FAR SOUTHWEST DRY UNTIL 22Z AND THE
IN HOUSE WRF THROUGH 00Z. AN ENSEMBLE OF HI RES MODELS...SPC
SSEO...EVEN SHOWS PRECIP STAYING SOUTH OF A MADISON TO LAKE
GENEVA LINE THROUGH 00Z AND THEN EVERYONE SEEING PRECIPITATION BY
03Z...WITH THE HEAVIEST PRECIP BETWEEN 03Z AND 09Z. WILL KEEP AN
EYE ON MODELS AND RADAR TRENDS TO SEE IF THE PRECIP ARRIVAL NEEDS
TO BE DELAYED EVEN MORE.
A LARGE TEMPERATURE SPREAD EXISTS ACROSS THE AREA...WITH 37 IN
KENOSHA AND 23 IN LONE ROCK AND 24 IN SHEBOYGAN. NONE OF THE
MODELS ARE DOING A GREAT JOB OF CAPTURING THE COOLER TEMPERATURES
TO THE NORTH AND NORTHWEST. MAY HAVE TO LOWER HIGH TEMPS IN THE
NORTHWEST. HOWEVER...TEMPS IN THE FAR SOUTHEAST MAY NEED TO BE
BUMPED UP ANOTHER DEGREE OR TWO. WILL CONTINUE TO MONITOR TRENDS.
&&
.PREV DISCUSSION... /ISSUED 338 AM CST THU JAN 10 2013/
TODAY AND TONIGHT...FORECAST CONFIDENCE...MEDIUM
KICKER TROUGH MOVING ASHORE ON THE WEST COAST WILL TAKE CLOSED LOW
CURRENTLY OVER SW TEXAS ON WATER VAPOR LOOPS...OPEN IT AND LIFT IT
NORTHEAST ACROSS THE SOUTHERN/CENTRAL PLAINS AS A NEGATIVELY TILTED
WAVE AS UPPER JET BUCKLES NORTHWARD OVER THE CENTRAL U.S./SRN CANADA
IN RESPONSE TO WESTERN TROUGH.
FIRST SURGE OF MID-LEVEL WAA/MOISTURE...ENHANCED BY 500-300MB DIFF
VORT ADVECTION WITH SHEARED VORTICITY IN AXIS OF SHORT WAVE RIDGE TO
THE NORTH OF SOUTHERN PLAINS TROUGH...LIFTS ACROSS SRN WI THIS
AFTERNOON. CONDENSATION PRESSURE DEFICITS OF 100 MB OR MORE ON
FORECAST 280K AND 285K SURFACES UNTIL MID-LATE AFTERNOON SUPPORT
LACK OF MOISTURE BELOW 10K FT ON CROSS SECTIONS AND FORECAST
SOUNDINGS THAT NEEDS TO SATURATE BEFORE ANY PRECIP REACHES THE
GROUND.
SATURATION WILL BE RAPID AROUND/AFTER 21Z. WILL TREND ONSET OF PCPN
FROM SW TO NE WITH LOWER CONDENSATION PRESSURE DEFICITS. PW/S
RAPIDLY JUMPING FROM ABOUT 0.25 INCH LATE MORNING TO A MAX AROUND
1.25 INCHES OVERNIGHT...OR 350-400 PCT OF NORMAL...AS GULF MOISTURE
FLOWS NWD AHEAD OF SURFACE WAVE. MAX FORCING/OMEGA BRINGS HEAVIEST
RAIN TO THE SOUTH AROUND 06Z...AND 09Z TO THE NORTHEAST CWA WITH
SOME TALL...SKINNY ELEVATED CAPE PROFILES ON FORECAST SOUNDINGS. NOT
ENOUGH INSTABILITY TO MENTION THUNDER...BUT A RUMBLE OR TWO NOT OUT
OF THE QUESTION.
SOME MODEL DIFFERENCES WITH SPEED OF 500 MB TROUGH AND TRACK OF VORT
MAX IN BASE OF TROUGH AND THE ASSOCIATED SURFACE WAVE LEADS TO
DIFFERING PLACEMENT OF AXIS OF HEAVIEST PRECIPITATION. WILL USE A
BLEND OF MODEL QPF AMOUNTS WHICH WILL BRING AROUND 1/2 INCH TO
WESTERN PORTIONS OF THE CWA UP TO 3/4 INCH IN THE SOUTHEAST...WITH
LOCALLY HIGHER AMOUNTS CLOSE TO AN INCH WITH THE BRIEF CONVECTIVE
POTENTIAL.
FRIDAY AND SATURDAY...FORECAST CONFIDENCE...MEDIUM
SURFACE LOW WILL BE OVERHEAD FRIDAY MORNING...WITH RAIN CONTINUING
TO WIND DOWN AS THE LOW LIFTS NORTHEAST. KEPT CHANCE FOR RAIN IN THE
MORNING...WITH THINGS TURNING DRY BY EARLY AFTERNOON. MAY BE SOME
DRIZZLE ACROSS THE WESTERN FORECAST AREA LATE AFTERNOON AND EVENING.
TEMPS WILL BE QUITE MILD...WITH EXPECTED HIGHS JUST A FEW DEGREES
BELOW RECORD VALUES.
KEPT MENTION OF FOG FRIDAY AND FRIDAY NIGHT...AS DEWPOINTS WILL BE
IN THE LOW TO MID 40S. TOUGH TO KNOW EXACTLY HOW MUCH FOG THERE WILL
BE IN THE EAST...ALL DEPENDING ON HOW MUCH SNOW IS LEFT BY THEN.
WOULD NOT BE SURPRISED IF THE FOG IS DENSE FOR A WHILE...ESPECIALLY
AREAS FARTHER WEST WHERE THE SNOW IS DEEPER AND WILL HOLD ON LONGER.
A STRONG COLD FRONT WILL MOVE THROUGH THE FORECAST AREA SATURDAY
MORNING. MODELS HAVE BEEN GOING BACK AND FORTH WITH THE TIMING OF
THIS FRONT...SO KIND OF A PAIN FIGURING OUT FRIDAY NIGHT LOWS AND
SATURDAY HIGHS...AS A CHANGE IN FRONT TIMING WILL IMPACT THESE QUITE
A BIT. EITHER WAY THOUGH...WILL EVENTUALLY SEE TEMPS HEAD DOWNWARD
SOMETIME SATURDAY MORNING...LIKELY CONTINUING TO FALL THROUGH THE
AFTERNOON. BREEZY WESTERLY WINDS BEHIND THE FRONT WILL MAKE IT FEEL
EVEN CHILLIER.
KEPT CHANCE FOR SNOW SOUTHEAST SATURDAY NIGHT...AS IT STILL LOOKS
LIKE LIGHT ACCUMULATIONS MAY BRUSH THE AREA. BEST CHANCE LOOKS
MAINLY SOUTHEAST OF A MILWAUKEE TO JANESVILLE LINE. UNLESS THIS
SYSTEM COMES FARTHER NORTH THAN CURRENTLY EXPECTED...WOULD ONLY SEE
MAYBE UP TO AN INCH TOWARD THE ILLINOIS BORDER.
SUNDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE...MEDIUM
ANY LINGERING LIGHT SNOW IS EXPECTED TO WIND DOWN QUICKLY SUNDAY
MORNING. LOOKS DRY THEN THROUGH THE MIDDLE OF NEXT WEEK. TEMPS WILL
BE COLDER EARLY NEXT WEEK...THOUGH NEAR TO JUST A FEW DEGREES BELOW
NORMAL FOR THIS TIME OF THE YEAR. COULD SEE HIGHS WARM TO A FEW
DEGREES ABOVE NORMAL BY MID WEEK.
AVIATION/12Z TAFS/...
WILL KEEP VFR CONDITIONS THROUGH MOST OF THE DAY WITH CLOUDS
THICKENING/LOWERING...THEN CONDITIONS WILL DETERIORATE QUICKLY WITH
SURGE OF DEEPER MOISTURE AND ONSET OF PRECIPITATION BETWEEN 21Z AND
00Z. MODEL SOUNDINGS AND MOS GUIDANCE IN GOOD AGREEMENT THAT IFR
CIGS AND VSBYS WILL SETTLE IN AT ALL TAF SITES BY 03Z FRIDAY AND
STAY DOWN THROUGH THE REMAINDER OF THE FORECAST PERIOD...EVEN UNTIL
18Z FRI AT KMKE. TEMPERATURES WILL BE WARM ENOUGH FOR ALL THE
PRECIPITATION TO BE LIQUID.
MARINE...
SOUTHEAST WINDS STEADILY INCREASE THROUGH THE DAY AS PRESSURE
GRADIENT TIGHTENS BETWEEN DEPARTING HIGH PRESSURE TO THE EAST AND
APPROACHING SURFACE LOW FROM THE SOUTH. WINDS SHIFT SOUTHWEST
DECREASE FOR A TIME FRIDAY AS WEAKENING SURFACE LOW MOVES THROUGH
REGION...THEN SOUTHERLY WINDS INCREASE LATE FRIDAY NIGHT AS
DEEPENING SURFACE LOW MOVES TOWARD REGION FROM THE NORTHERN PLAINS.
WILL ISSUE A SMALL CRAFT ADVISORY FROM LATE THIS AFTERNOON UNTIL 00Z
SATURDAY...THOUGH IT MAY HAVE TO BE EXTENDED IF WAVES TO NOT SUBSIDE
AS EXPECTED BEFORE WINDS INCREASE LATE FRIDAY NIGHT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 6 PM CST FRIDAY
FOR LMZ643>646.
&&
$$
UPDATE...MEB/SM
TODAY/TONIGHT AND AVIATION/MARINE...REM
FRIDAY THROUGH WEDNESDAY...DDV