Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/08/12
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
850 PM MST FRI DEC 7 2012
.UPDATE...CURRENT RADAR AND CAMS SHOW LIGHT SNOW SHOWERS
CONTINUING IN THE MOUNTAINS AND A LOT OF VIRGA ON THE EASTERN
PLAINS. CANT RULE OUT A LITTLE OF THIS VIRGA REACHING THE GROUND
JUST TO THE EAST OF DENVER IN THE NEXT COUPLE HOURS...THEN
INCREASING DOWNSLOPE COMPONENT SHOULD TAKE CARE OF THAT OVERNIGHT.
SO FAR...WIND SPEEDS HAVE REMAINED RATHER LOW AND ARE NOT
INCREASING. HOWEVER...WINDS WILL INCREASE SIGNIFICANTLY LATER
TONIGHT INTO SATURDAY MORNING AS NEXT UPPER LEVEL SPEED MAX
ADVANCES TOWARD SOUTHERN WYOMING. NOT ENTIRELY CONFIDENT WE WILL
REACH HIGH WIND CRITERIA DUE TO MOISTURE AND SNOWFALL IN THE HIGH
COUNTRY WHICH ACTS AGAINST MOUNTAIN WAVE DEVELOPMENT...BUT
CERTAINLY WONT DROP A WARNING AT THIS POINT WITH 50-65 KT
MOUNTAIN TOP FLOW.
WITH REGARD TO SNOW HIGHLIGHTS IN THE HIGH COUNTRY...WILL ISSUE AN
ADVISORY FOR ZONE 31 WHERE WE ARE EXPECTING ADVISORY CRITERIA SNOW
AS WELL AS CONSIDERABLE BLOWING/DRIFTING SNOW. ON THE FRONT RANGE
MOUNTAINS...WE ALREADY HAVE A HIGH WIND WARNING OUT. WE WILL
LIKELY SEE ADVISORY CRITERIA SNOWFALL THERE AS WELL STARTING
TOMORROW AFTERNOON AND CONTINUING THROUGH SATURDAY NIGHT. THE
MOST LIKELY SCENARIO IS TO LATER REPLACE THE HIGH WIND WARNING
WITH AN ADVISORY OR WINTER STORM WARNING DEPENDING ON THE STRENGTH
OF WINDS AND INTENSITY OF SNOW.
ON THE PLAINS...STILL LOOKING AT HIGHEST CHANCE OF SNOW IN/NEAR
THE FRONT RANGE FOOTHILLS SATURDAY NIGHT IN THE WAKE OF FRONTAL
PASSAGE.
&&
.AVIATION...WINDS ARE TRANSITIONING AROUND TO SOUTH/SOUTHWESTERLY
AND WILL REMAIN THERE OVERNIGHT. THIS WOULD KEEP ANY THREAT OF
FLURRIES TO THE NORTHEAST OF KDEN. CEILINGS COULD LOWER A LITTLE
WITH ILS LANDING POSSIBLE THROUGH 06Z...THEN SHOULD INCREASE
AGAIN WITH DEEPER SOUTH/SOUTHWEST FLOW. NO CHANGES TO REST OF
FORECAST.
&&
.PREV DISCUSSION... /ISSUED 352 PM MST FRI DEC 7 2012/
SHORT TERM...SNOW STILL ONGOING ACROSS MOUNTAINS...WITH SOME
ENHANCEMENT SHOWING UP ON RADAR ALONG THE CONTINENTAL DIVIDE.
LATEST WATER VAPOR INDICATE SOME SORT OF WAVE MOVING ACROSS
WYOMING WHICH MAY BE HELPING WITH THE SNOWFALL. ACROSS
PLAINS...SURGE MOVED ACROSS AREA WITH NORTHEAST WINDS UP TO THE
FOOTHILLS. LATEST RUC CROSS SECTIONS CONTINUE TO SHOW GOOD
MOISTURE ACROSS THE MOUNTAINS THROUGH TONIGHT AND OROGRAPHICS
SHOULD HELP TO KEEP SOME SNOW GOING THOUGH THERE APPEARS FROM
UPSTREAM OBSERVATIONS AND SATELLITE OF A BREAK IN THE MOISTURE. SO
THERE MAY BE SOME DECREASE IN THE SNOW AND WILL MAINTAIN THE
CHANCE POPS. WINDS TO INCREASE TONIGHT AHEAD OF AN APPROACHING
SYSTEM. LATEST MODELS CONTINUE TO SHOW THE DEVELOPMENT OF A DECENT
MOUNTAIN WAVE AND MOUNTAIN TOP INVERSION AFTER MIDNIGHT...WITH RUC
CROSS SECTIONS INDICATING 40 KTS OF CROSS MOUNTAIN FLOW BY 08Z.
LATEST NAM CROSS SECTIONS INDICATING EVEN STRONGER CROSS MOUNTAIN
FLOW OVERNIGHT AND INTO MUCH OF SATURDAY...AROUND 45 KTS AT
MOUNTAIN TOP AT 09Z TO A WHOPPING 75 KTS FROM 15Z TO ROUGHLY 21Z.
THESE VALUES LOOK A BIT OVERDONE...BUT MODELS ARE STILL SIMILAR IN
SHOWING HIGH WIND POTENTIAL FOR THE MOUNTAINS AS WELL AS THE
FOOTHILLS...THOUGH THE SHEAR MAY NOT IDEAL AND INVERSION MAY BE
BREAKING UP AS PATTERN TRANSITIONS FROM A CHINOOK PATTERN
OVERNIGHT TO A BORA PATTERN BY SATURDAY AFTERNOON WHEN THE MID
LEVEL ASCENT INCREASES. BEST TIME FOR THE HIGH WINDS THREAT WILL
BE 09Z TO 21Z SATURDAY. WILL ISSUE A HIGH WIND WARNING FOR THE
MOUNTAINS AND FOOTHILLS FROM 06Z FRIDAY THROUGH 00Z SUNDAY...OR
BASICALLY ALL OF SATURDAY. SHOULD SEE GUSTS OF AT LEAST 75 MPH
DURING THIS TIME FRAME. SHOULD ALSO SEE SNOW INCREASE AROUND 18Z
SATURDAY ACROSS THE MOUNTAINS AS THE JET SAGS INTO THE STATE AND
LIFT INCREASES WITH UP TO 4 INCHES POSSIBLE BY THE EVENING. WINDS
WILL ALSO CREATE BLOWING SNOW...MAINLY DURING THE AFTERNOON.
ACROSS PLAINS...CLOUDS TO GRADUALLY INCREASE THIS EVENING AS WINDS
SHIFT TO A DRAINAGE PATTERN. WINDS MAY GET A BIT GUSTY NEAR THE
FOOTHILLS OVERNIGHT AS DOWNSLOPE WINDS DEVELOP. ON
SATURDAY...MODELS CONTINUE TO SNOW CANADIAN FRONT MOVING ACROSS
THE AREA DURING THE AFTERNOON...WITH NORTHEAST UPSLOPE WINDS
HOLDING OFF UNTIL THE EVENING. GFS SHOWS SOME PRECIP ALONG THE
NORTHEAST CORNER LATE IN THE AFTERNOON. FOR NOW WILL KEEP THINGS
DRY THROUGH THE AFTERNOON. COLDER AIR TO MOVING INTO THE AREA
AFTER 00Z.
LONG TERM...A SWIFT RIVER OF MOIST PACIFIC AIR ROUNDING THE
SOUTH SIDE OF A BROAD UPPER LEVEL TROUGH IS FORECAST TO BECOME
POSITIONED OVER NORTHERN COLORADO SATURDAY NIGHT. MODELS SHOW A
110-130KT WEST- EAST ORIENTED JET AT THE CORE OF THIS FLOW OVER
THE COLORADO FRONT RANGE MTNS FOR MOST OF SATURDAY NIGHT. HOWEVER
THROUGH THE NIGHT MODELS SHOW THE UPPER TROUGH DIGGING SOUTHWARD
TOWARD THE FOUR CORNERS WITH THE MEAN FLOW ALOFT BECOMING
PROGRESSIVELY MORE NORTHERLY IN DIRECTION AND SPEEDS DECREASING
SUBSTANTIALLY SUNDAY MORNING WITH THE BACK SIDE OF TROUGH SHIFTING
EASTWARD. CROSS SECTIONS INDICATE CROSS BARRIER WINDS OVERNIGHT ON
THE ORDER OF 45- 55KTS AT MTN TIME LEVEL. THE STRONG WINDS WILL
LIKELY COMBINE WITH SNOWFALL AND LIGHT TO MODERATE ACCUMULATIONS
TO PRODUCE AREAS OF BLOWING SNOW IN THE HIGH
COUNTRY...PARTICULARLY ON THE HIGH MTN PASSES AND UP AROUND THE
EISENHOWER TUNNEL OVERNIGHT. MAY BECOME NECESSARY TO HOIST A
WINTER WEATHER ADVISORY FOR SNOW AND BLOWING SNOW FOR THE MTN AND
FTHLS ZONES SHOULD THE NEXT MODEL RUN INDICATE A SIMILAR SETUP. AT
LOWER ELEVATIONS EAST OF THE MTNS...CANADIAN COLD FRONT DROPS
SOUTH ACROSS THE NORTHEAST PLAINS OF COLORADO EARLY SATURDAY AS
PER LATEST MODEL GUIDANCE FOLLOWED BY 6-9 HOURS OF NORTH-
NORTHEAST SFC-700 MB FLOW. SNOW CHANCES AND AMOUNTS EAST OF THE
MTNS LOOKING LESS IMPRESSIVE WITH THE 12Z AND 18Z MODEL RUNS.
MODEL SNOW GRIDS CONFINE THE BULK OF SNOW ACCUMULATION RIGHT UP
AGAINST THE FRONT RANGE FOOTHILLS AND OVER THE PALMER DIVIDE.
MODELS BARELY SHOW ANY SNOW ACCUMULATION EAST OF I-25 OR NORTH OF
U.S. HIGHWAY 6 FOR THIS STORM SYSTEM. OVERALL MODELS HAVE BEEN ALL
OVER THE PLACE WITH SNOW TOTALS AND COVERAGE...BUT ONE MODEL...THE
NAM...HAS CONSISTENTLY SHOWED LITTLE IF ANY SNOW EAST OF THE MTNS.
FOR THIS FCST PACKAGE LARGELY RELIED ON THE SREF TO LOAD QPF AND
SNOW AMTS IN THE FORECAST GRIDS.
LOOKING AHEAD TO SUNDAY...SHOULD SEE SNOWFALL DIMINISHING FORM NORTH
TO SOUTH IN THE MTNS AND NEARBY PLAINS THROUGH THE DAY...WITH LITTLE
ADDITIONAL ACCUMULATION ANTICIPATED. MAIN CONCERN ON SUNDAY WILL BE
THE MUCH BELOW AVERAGE TEMPERATURES AND BITTER WIND CHILLS WITH
NORTHERLY WINDS OF 10-25 MPH. DO NOT EXPECTED TO SEE DAYTIME
TEMPERATURES CLIMBING ABOVE THE UPPER 20S ANYWHERE IN THE FORECAST
AREA. WITH CLEARING SKIES OVERNIGHT...GOOD BET WE/LL SEE THE COLDEST
TEMPERATURES DO THE WINTER SEASON THUS FAR...WITH MTN VALLEYS
MERCURY READINGS WELL BELOW ZERO BY MORNING.
FOR MONDAY...ANOTHER SYSTEM RACES OUT OF THE PACIFIC NORTHWEST AND
ACROSS COLORADO BRINGING ANOTHER SHOT OF SNOW AND WIND TO THE MTNS
AND HIGH VALLEYS. COULD SEE A BIT OF LIGHT SNOW DURING THE
AFTERNOON/EVENING ON THE NORTHEAST PLAINS WITH ANTICYCLONIC UPSLOPE
FLOW FOR A TIME. NEW ACCUMULATIONS SHOULD BE LIGHT AND CONFINED TO
AREAS ABOVE TIMBERLINE AND NORTHWEST FACING MTN SLOPES.
LATER IN THE WEEK...SHOULD SEE A GRADUAL RETURN TO WARMER AND DRIER
CONDITIONS.
AVIATION...EASTERLY WINDS TO GRADUALLY DECREASE AND SWITCH TO
DRAINAGE DURING THE EVENING. SPEEDS OF AROUND 10 KTS TO PREVAIL
THOUGH SOME GUSTS TO 25 KTS POSSIBLE AT BJC AS DOWNSLOPE FLOW
DEVELOPS. WINDS TO SHIFT TO THE NORTHWEST BY 18Z THEN NORTH AROUND
21Z AS FRONT MOVES ACROSS AREA. COULD SEE SOME GUSTS TO 25 KTS
WITH FRONTAL PASSAGE. VFR CONDITIONS TO PREVAIL WITH A GRADUAL
INCREASE IN MID AND HIGH LEVEL MOISTURE. CEILINGS OF AROUND 6000
FEET COULD DEVELOP AFTER 21Z WITH POTENTIAL FOR ILS IMPACTS.
PRECIPITATION SHOULD HOLD OFF UNTIL THE EVENING WHEN THE COLDER
AIR MOVES OVER THE AREA.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL 5 PM MST SATURDAY FOR COZ033>036.
WINTER WEATHER ADVISORY FROM 8 AM SATURDAY TO 5 AM MST SUNDAY
FOR COZ031.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....BAKER
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
345 PM MST THU DEC 6 2012
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 345 PM MST THU DEC 6 2012
DENDRITIC LAYER IS DRYING OUT ACROSS THE NORTHERN CWA THIS AFTERNOON
WITH MOST AREAS NORTH OF HIGHWAY 50 SEEING MAINLY CLOUDS AT MOUNTAIN
TOP LEVEL AND SOME ISOLATED OROGRAPHIC SHOWERS. DOWN SOUTH...MOIST
UNSTABLE FLOW CONTINUES TO PROGRESS SLOWLY SOUTHWARD ACROSS THE SAN
JUANS. WEB CAMS AROUND TEX AND ALONG THE RED MOUNTAIN PASS INDICATED
THE CONVECTION WAS AIDING THE DENDRITIC GROWTH WITH BIG FLAKES
COMING DOWN. WARM LOW LEVEL ROAD TEMPERATURES HOWEVER HAVE NOT BEEN
FAVORABLE FOR THE SNOW TO ACCUMULATE BELOW 9000 FEET. SNOTEL DATA
NOT MUCH HELP IN THIS WARM AIRMASS BUT SWE HAS BEEN INCREASING
ACROSS THE HIGHER LOCATIONS BY A FEW TENTHS. THERE SHOULD BE A
DECREASING TREND THROUGH THE EVENING AS THE MOISTURE PLUME CONTINUES
TO BE FORCED SOUTHWARD AND THE CONVECTIVE ELEMENT WANES.
12Z U/A ANALYSIS CONTINUED TO SHOW TWO MAIN VORTICES OVER
NOAM ...ONE ACROSS THE GULF AND LANDMASS OF AK AND THE OTHER
CENTERED NORTH OF HUDSON BAY. THESE TWO FEATURES WILL BEGIN TO
INTERACT MORE DIRECTLY OVER THE NEXT 24 TO 48 HOURS AND PULL BOTH
MOISTURE AND VERY COLD AIR INTO THE WESTERN CONUS AND BRING THE MUCH
ANTICIPATED PATTERN CHANGE.
DARKENING IN WATER VAPOR IMAGERY ACROSS WESTERN WASHINGTON THIS
AFTERNOON INDICATES THE PUSH OF THE BRANCH OF THE POLAR JET MAX
INTO THE WEST. THIS BROAD CYCLONIC JET WILL PUSH ACROSS THE
NORTHERN ROCKIES INTO THE PLAINS BEGINNING TONIGHT AND SLOWLY SAG
TOWARD THE NORTHERN COLORADO BORDER THROUGH TOMORROW NIGHT. 305K
MOISTURE TRANSPORT VECTORS SHOWS A CONTINUAL FEED OF PACIFIC
MOISTURE BEING PULLED ALONG WITH THIS JET DIRECTED AT NORTHERN
UTAH AND COLORADO WELL INTO THE WEEKEND. WHAT WILL BE LACKING WITH
THIS MOISTURE TONIGHT WILL BE LARGE SCALE ASCENT. 1.5 PVU PRESSURE
PLOTS SHOW THE LEAD PIECE OF ENERGY FROM THE DECAYING WESTERN LOW
TRANSLATING ACROSS ACROSS THE NORTHERN ROCKIES. HOWEVER THIS WAVE
WILL CONTRIBUTE AN INCREASE TO THE WESTERLY MID LEVEL FLOW OVER
NORTHERN UTAH AND COLORADO AND PUSH IN COLDER AIR ALOFT. WITH THE
THE LACK OF STRONG DYNAMICS AND A SURFACE FOCUS...THE NORTHERN AND
CENTRAL HIGH COUNTRY LOOK FAVORED FOR PERIODIC OROGRAPHIC SNOW
SHOWERS THROUGH SATURDAY MORNING. THE SOUTHERN MOUNTAIN WILL BE ON
THE OUTSIDE LOOKING IN DURING THIS TIME. DENDRITIC SATURATION
LOOKS TO TAKE PLACE ACROSS THE NORTHERN MOUNTAINS AFTER MIDNIGHT
AND SPREAD SOUTHWARD TOWARD THE I-70 CORRIDOR BY TOMORROW
AFTERNOON. H7 TEMPS WILL BE COOLING TO THE -6 TO -10 BY MID
MORNING ON FRIDAY SO SOME SNOWFALL MAY MAKE IT DOWN THE SBS AND
HDN AREAS FOR A DUSTING OF SNOW. THE MAIN FOCUS HOWEVER WILL BE
OVER THE FLAT TOPS...PARK AND GORE RANGES WHERE GENERALLY 2 TO 3
INCHES IS EXPECTED BY TOMORROW EVENING...WITH LOCALLY HIGHER
AMOUNTS POSSIBLE ON NORTHWEST FACING SLOPES.
LARGE SCALE ASCENT WILL INCREASE OVER THE NORTH FRIDAY NIGHT AS
THE RR OF THE UPPER JET MOVES OVER SOUTHERN WYOMING AND THE NEXT
UPSTREAM WAVE PUSHES INTO THE NW WYOMING. MOIST WESTERLY
OROGRAPHICS ARE STILL IN PLACE SO SNOW SHOWERS ACROSS THE NORTHERN
COLORADO MOUNTAINS STILL A GOOD BET AND RAISED POPS. THESE WILL
ONLY INCREASE THROUGH THE DAY AS THE COLD FRONT FROM THE NORTH
APPROACHES. TEMPERATURES WILL BE A BIT COOLER THE NEXT WITH LESS
CLOUD COVER TONIGHT AND COOLER AIR ARRIVING FRIDAY NIGHT. HIGHS
TOMORROW WILL BEGIN A DONN WARD TREND BY A FEW DEGREES BUT STILL
REMAIN ABOVE EARLY DECEMBER NORMALS.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 345 PM MST THU DEC 6 2012
MODELS REMAIN CONSISTENT IN SHOWING A CHANGE TO COLDER AND POSSIBLY
UNSETTLED WEATHER FOR ERN UT/WRN CO...BEGINNING THIS WEEKEND AND
CONTINUING THROUGH MUCH OF NEXT WEEK. GFS AND ECMWF ENSEMBLES
INDICATE THE DEVELOPMENT OF A LARGE TROUGH ACROSS MUCH OF THE CONUS
WHILE AN UPPER RIDGE AMPLIFIES IN THE NERN PACIFIC OCEAN. THE
CHALLENGE REMAINS THE TRACK OF THE PERIODIC SHORTWAVES THAT TOP THE
RIDGE AND DROP INTO THE WESTERN AND CENTRAL USA.
SATURDAY-SUNDAY: THE FIRST OF THESE SHORTWAVES DROPS OUT OF THE GULF
OF AK AND SWINGS ACROSS THE NORTHERN ROCKIES ON SATURDAY...
EVENTUALLY DEVELOPING A SURFACE LOW OVER THE DAKOTAS. THE TRAILING
COLD FRONT LOOKS TO DROP INTO THE NORTH DURING THE DAY ON
SATURDAY....THEN SWEEP ACROSS THE REMAINDER OF THE FORECAST AREA SAT
NIGHT AS THE UPPER JET DIGS A POSITIVE-TILTED TROUGH SOUTH ACROSS
THE AREA. AS DESCRIBED IN LAST NIGHT/S DISCUSSION...DYNAMIC AND
FRONTAL FORCING COMBINED WITH OROGRAPHIC LIFT PROVIDED BY STRONG
WESTERLIES AND A MOISTENING AND LOWERING DENDRITIC SNOW GROWTH
REGION WILL BRING MEASURABLE SNOW TO THE NORTHERN MOUNTAIN BY
SATURDAY AFTERNOON. STRONG GUSTY WEST WINDS WILL CREATE AREAS OF
BLOWING SNOW SAT AFTERNOON. SNOW THEN SPREADS INTO THE CENTRAL AND
SOUTHERN MOUNTAINS SAT NIGHT...WITH FLOW SHIFTING TO THE NW AND N.
COLDER AIR BEHIND THE FRONT WILL QUICKLY DROP SNOW LEVELS TO VALLEY
FLOORS. NW-N FLOW SHOULD KEEP SOME SNOW SNOW SHOWERS OVER THE CO
MTNS ON SUNDAY WHILE DRYING AND SUBSIDENCE MOVE INTO ERN UT AND NW
CO BEHIND THE UPPER TROUGH.
A BIT SURPRISED AT THE PAUCITY OF SNOWFALL GENERATED BY THE 12Z NAM
AND PREFERRED THE GFS/ECMWF WHICH TRACKED THE DIGGING TROUGH SAT
NIGHT A LITTLE FARTHER WEST. BUT BECAUSE OF THIS...UNCERTAINTY
PERSISTS. INITIAL ESTIMATES FOR SNOW ACCUMS FOR SAT-SUNDAY MORNING
LOOK TO BE 5-10 INCHES FOR THE NRN CO MTNS AND THE CENTRAL MTNS NEAR
THE DIVIDE. LESSER AMOUNTS ELSEWHERE THOUGH AREAS TO WATCH ARE THE
NORTH SIDES OF GRAND MESA AND THE SAN JUANS IN THE NW-N FLOW. ERN
UT...HOWEVER...LOOKS TO RECEIVE THE LEAST.
COLDER TEMPS ARRIVE BEHIND THE FRONT WITH HIGH TEMPS SUNDAY PERHAPS
15-20 DEGREES COLDER THAN THE HIGH TEMPS ON FRIDAY. OVERNIGHT LOWS
IN THE SINGLE DIGITS AND TEENS ARE EXPECTED SUNDAY NIGHT AREA-WIDE.
ISSUED A SPECIAL WEATHER STATEMENT EARLIER THIS AFTERNOON TO ADDRESS
THE UPCOMING CHANGE TO COLDER WEATHER AND POSSIBILITY OF SIGNIFICANT
SNOWFALL.
MONDAY-THURSDAY: COOL NORTHWESTERLY FLOW EXPECTED THROUGH MIDWEEK.
ANOTHER SHORTWAVE DIVES THROUGH THE REGION ABOUT MONDAY NIGHT. GFS
BRINGS A THIRD INTO THE GREAT BASIN TOWARD THU...BUT THE 12Z ECMWF
DEVELOPS THIS INTO A CLOSED LOW ALONG THE WEST COAST. WITH MODEL
INCONSISTENCIES NEXT WEEK...USED THE CONSENSUS MODEL FOR A RATHER
BROAD BRUSH AND VARYING CHANCE OF PRECIPITATION FOR MAINLY THE MTNS
NEXT WEEK.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 345 PM MST THU DEC 6 2012
VFR CONDITIONS ARE IN PLACE ACROSS THE MAJORITY OF THE TERMINAL
SITES THIS AFTERNOON...WITH A FEW LOWER CLOUDS HANGING IN NEAR THE
KASE TERMINAL LATE THIS AFTERNOON IN THE UPVALLEY FLOW. EXPECT
CONDITIONS TO IMPROVE HERE AS LOCAL WEB CAMS BEGINNING TO SHOW
MORE SUNSHINE. THE BULK OF TH PRECIPITATION REMAINS OVER THE
SOUTHERN MOUNTAINS WHERE MOUNTAIN OBSCURATIONS MAY REACH LOWER
PASSES AND HIGH VALLEY REGIONS. UP NORTH WHERE DRIER AIR HAS
INVADED MOST CLOUDS ARE ROOTED THE MOUNTAIN TOPS. CONDITIONS
SHOULD IMPROVE ACROSS THE SOUTH THROUGH THE EVENING AS MOISTURE
AND LIFT MOVES SOUTHWARD. UP NORTH INCREASING MOIST WESTERLY FLOW
SHOULD WILL LEAD TO LOWER CLOUD AND SNOW SHOWER FORMATION OVER THE
HIGH COUNTRY WITH MOUNTAIN OBSCURATION AND MVFR CONDITIONS
PERSISTING THROUGH THE EARLY AFTERNOON HOURS. MOST TAF SITE
HOWEVER LOOK TO PREVAIL AND VFR CONDITIONS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...15
LONG TERM...JAD
AVIATION...15
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
303 PM MST THU DEC 6 2012
.SHORT TERM...MID LEVEL SHORT WAVE MOVING INTO CENTRAL PLAINS WITH
DRYING AND SUBSIDENCE OVERTAKING CFWA. SNOW SHOWERS ACROSS
MOUNTAINS HAVE BEEN ON THE DECREASE BUT STILL DECENT OROGRAPHICS
FOR SOME LIGHT SNOW HUGGING CONTINENTAL DIVIDE AS SHOWN BE WEB
CAMS. ALSO SOME SHOWERS ACROSS PARK COUNTY. MODEL CROSS SECTIONS
SHOW A DECREASE IN MOISTURE THROUGH THE EVENING...SO TREND OF
DECREASING SNOW STILL LOOKING REASONABLE. FLOW ALOFT INCREASES
AFTER MIDNIGHT WITH RUC CROSS SECTIONS SHOWING CROSS MOUNTAIN FLOW
INCREASING TO 40 KTS AT MOUNTAIN TOP BY 08Z. FORECAST SOUNDINGS
SHOWING MOUNTAIN TOP INVERSION DEVELOPING AFTER 06Z WITH POTENTIAL
FOR A MOUNTAIN WAVE. WITH INCREASING MID LEVEL SUBSIDENCE
EXPECTED...SHOULD SEE WINDS INCREASE AFTER MIDNIGHT...ESPECIALLY
ACROSS MOUNTAINS AND NORTHERN FOOTHILLS BUT SHOULD STAY BELOW HIGH
WIND CRITERIA. ON FRIDAY... MODERATE WESTERLY FLOW ALOFT TO
CONTINUE. WINDS TO REMAIN GUSTY ACROSS THE MOUNTAINS AND ALONG
FOOTHILLS...WITH A SLIGHT DECREASE BY THE AFTERNOON. MODEL CROSS
SECTIONS SHOW MOISTURE INCREASING DURING THE MORNING ALONG WITH
SOME INCREASE IN MID LEVEL QG ASCENT. WITH FAVORABLE OROGRAPHICS
EXPECTED ACROSS MOUNTAINS...SHOULD SEE SNOW CHANCES INCREASE BY
THE AFTERNOON. ANY ACCUMULATIONS EXPECTED TO BE LIGHT AND
CONFINED THE THE WEST FACING SLOPES. ACROSS PLAINS...DRY
CONDITIONS TO PREVAIL WITH A GRADUAL INCREASE IN CLOUD COVER.
TEMPERATURE AND THICKNESS GUIDANCE SHOWING LITTLE CHANGE FROM
TODAY`S READINGS...PERHAPS A FEW DEGREES WARMER ACROSS PLAINS.
.LONG TERM...TO START OFF...THERE`S A POSSIBILITY OF STRONG IF NOT
HIGH WINDS IN THE MTNS AND FRONT RANGE FOOTHILLS FRIDAY NIGHT AND
SATURDAY MORNING. MODELS SHOW A +120KT POLAR JET ROUNDING THE
SOUTH SIDE OF POTENT UPPER LEVEL TROUGH TRANSLATES SOUTHWARD OVER
THE FORECAST AREA LATE ON FRIDAY. THE CORE OF THIS JET IS PROGGED
TO PASS OVER THE FRONT RANGE BETWEEN 06Z-12Z/SATURDAY. AT THE
SAME TIME...AS THE MTN LAYER GROWS INCREASINGLY STABLE AND CROSS
SECTIONS SHOW A HIGH AMPLITUDE MTN WAVE FORMING OVER THE FRONT
RANGE WITH A CROSS BARRIER WIND COMPONENT OF 60-75 KTS WITHIN THE
700-550 MB LAYER. MAY BE NECESSARY TO ISSUE A HIGH WIND WATCH FOR
THE RIDGES AND EAST SLOPES OF MTN ZONES 33..34 AND FOOTHILL ZONES
35 AND 36 SHOULD THE NEXT MODEL RUN CONTINUE TO INDICATE WINDS OF
THIS MAGNITUDE. ATTENTION NEXT TURNS TO THE APPROACHING TROUGH/S
IMPACT ON THE FORECAST AREA THIS WEEKEND. STARTING WITH SATURDAY...
STG AND GUSTY WEST-NORTHWEST WINDS IN THE MTNS AND FTHLS SHOULD
EASE WITH THE JET CONTINUING TO MIGRATE SOUTH. AN POCKET OF
MODERATE QG ASCENT COUPLED WITH UPSLOPE FORCING SHOULD BEGIN TO
CRANK OUT SNOW IN THE NRN MTN RANGES BY EARLY AFTERNOON ON
SATURDAY...IF NOT SOONER. THROUGH THE DAY SHOW SEE THIS SNOW FIELD
SPREADING SOUTHWARD AS COLD AIR SPILLS IN FROM WYOMING. ON THE
PLAINS...CONDITIONS LOOK DRY IN THE MORNING WITH LIGHT DOWNSLOPE
FLOW. HOWEVER BY LATE IN THE DAY COULD SEE A FEW SHOWERS DRIFTING
OFF THE NRN FRONT RANGE AND OVER PORTIONS OF THE I-25 URBAN
CORRIDOR. TEMPERATURES STILL LOOK TOO WARM FOR ANYTHING BUT
RAIN...ALTHOUGH RIDGE UP AGAINST THE FOOTHILLS AND NEAR THE WY
BORDER...COULD SEE A RAIN/SNOW MIX BEFORE SUNSET. THEN
OVERNIGHT...FORCING FOR ASCENT INCREASES AS THE CORE OF THE UPPER
TROUGH MAKES ITS WAY OVER SRN WY/NRN COLORADO. A MAJORITY OF THE
MODELS ALSO SHOW A STRONG COLD FRONT DROP SOUTH ACROSS THE PLAINS
DURING THE ERLY EVENING HOURS. THIS SETS IN PLAY AT LEAST 9 HRS OF
ANTICYCLONIC UPSLOPE FLOW FOR AREAS ROUGHLY EAST OF THE
CONTINENTAL DIVIDE. BEST OROGRAPHIC LIFT OCCURS FM 06Z TO
15Z/SUNDAY. THIS IS THE PERIOD WHEN MODELS GENERATE THE BULK OF
PCPN/SNOWFALL FOR THE FORECAST AREA. SNOW TOTALS...STILL
TENTATIVE...VARY FROM 3-9 INCHES IN THE HIGH COUNTRY...TO A TRACE
UP TO 5 INCHES ON THE PLAINS. MAY SEE A BIT MORE FOR THE PALMER
DIVIDE WHERE N-NELY BNDRY FLOW WOULD FAVOR MORE SNOW FORMATION.
ON SUNDAY...MODELS SHOW THE TROUGH DROPPING SOUTH-SOUTHEAST WHICH
PULLS INCREASINGLY COLDER AIR DOWN FOR WYOMING THROUGH THE DAY.
SUNDAY APPEARS TO BE THE COLDEST DAY FOR THE NEXT SEVERAL DAYS
WITH HIGHS ON SUNDAY AS MUCH AS 15-25F BELOW AVERAGE...WITH
COLDEST DAYTIME TEMPERATURES EAST OF THE MTNS. BY SUNDAY NIGHT
UNDER CLEARING SKIES EVERYWHERE WILL BE IN THE GRIPS OF THE VERY
COLD AIRMASS. WILL LIKELY SEE SUBZERO READINGS IN THE MTN VALLEYS
AND POSSIBLY NEAR ZERO LOWS IN LOW AREAS ON THE PLAINS.
MONDAY STILLS LOOKS COLD WITH TEMPS SEVERAL DEGREES BELOW
AVERAGE. THROUGH THE DAY COULD SEE SKIES QUICKLY CLOUDING UP AGAIN
AS ANOTHER CLIPPER RACES SOUTH OUT OF THE MONTANA ROCKIES. COULD
SEE SNOW DEVELOPING IN THE NRN MTNS BY THE AFTERNOON AND POSSIBLY
ON THE PLAINS BY EVENING. WITH SO MUCH OCCURRING TO THIS POINT
WILL STOP FOR NOW.
&&
.AVIATION...SOUTHEAST WINDS TO WEAKEN ACROSS THE AREA AND BECOME
SOUTHERLY AS DRAINAGE FLOW DEVELOPS. THE DIRECTION WILL BE MORE
WESTERLY AT BJC AS DOWNSLOPE PREVAILS. SPEEDS OF AROUND 8 KTS TO
PREVAIL...THOUGH SOME GUSTS TO 20 KTS WILL BE POSSIBLE AT BJC
BETWEEN 08Z AND 16Z. BY 18Z WINDS TO BECOME NORTHWESTERLY AND
SHOULD CONTINUE THROUGH THE AFTERNOON. VFR TO PREVAIL WITH A
GRADUAL INCREASE IN MID AND HIGH LEVEL MOISTURE. CEILINGS TO
REMAIN UNLIMITED.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BAKER
LONG TERM....D-L
AVIATION...BAKER
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1045 AM MST THU DEC 6 2012
.UPDATE...
ISSUED AT 829 AM MST THU DEC 6 2012
HAVE ADJUSTED POPS UPWARD ACROSS THE SOUTHERN MOUNTAINS AND VALLEY
LOCATIONS LOOKING AT THE LATEST RADAR...SATELLITE AND WEB CAM
TRENDS. NEWEST NAM MODEL IS ALSO TRENDING THIS WAY SHOWING THE
MOISTURE TAP SEEN IN THE GOES DERIVED IMAGERY NOSING ACROSS THE 4
CORNERS REGION ALONG WITH SOME JET DYNAMICS. EPV FIELDS AND RADAR
PICS ALSO SHOW THIS AREA IS MORE CONVECTIVE IN NATURE SO SOME
QUICK BURSTS OF SNOWFALL MAY OCCUR AT THE HIGHER ELEVATIONS.
FARTHER NORTH...MOIST WESTERLY FLOW WILL CONTINUE TO BRING
SNOWFALL TO THE NORTHERN AND CENTRAL MOUNTAINS AND ADJACENT HIGHER
VALLEYS THIS MORNING...BUT THE DENDRITIC LAYER LOOKS TO BE DRYING
OUT THROUGH THE AFTERNOON. WILL CONTINUE TO MONITOR TRENDS FOR
ADDITIONAL UPDATES.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 409 AM MST THU DEC 6 2012
SHORT-TERM MODELS ARE STILL HAVING A TOUGH TIME DECIDING WHAT THEY
WANT TO DO IN TERMS OF THE DISTURBANCE MOVING THROUGH EARLY THIS
MORNING THROUGH THE AFTERNOON. THE NAM AND RAP ARE THE LEAST
IMPRESSIVE WITH THIS SYSTEM WITH FAR LESS SNOW AMOUNTS THAN THE
GFS. DESPITE THE DIFFERENCE IN SNOW AMTS BETWEEN MODELS...THE
CONSISTENT THING IS THAT 700MB TEMPS ARE AROUND -3C IN THE NORTHERN
MTNS WITH -1C IN THE CENTRAL MTNS. THIS PUTS SNOW LEVELS AT AROUND
7 OR 8 KFT. 700MB WINDS ARE BETWEEN 5 AND 10 KTS...FAR LESS THAN
THEY WERE 24 HRS AGO. THIS DOES NOT FAVOR STRONG UPSLOPE FLOW OR
STRONG OROGRAPHIC EVENT. THE BULK OF THE PRECIP LOOKS TO OCCUR WITH
THE UPPER LEVEL JET STREAK THAT IS SET TO MOVE THROUGH THIS MORNING
BETWEEN 09Z AND 15Z ACCORDING TO TIME HEIGHTS. CURRENT OBSERVATIONS
AS OF 09Z SHOW SOME LIGHT SNOW FALLING OVER MT WERNER NEAR SBS AND
SOME BRIEF LIGHT SNOW IN THE ASPEN AREA THIS PAST EVENING. LIGHT
RAIN JUST STARTED IN CRAIG AS WELL. SATELLITE TRENDS SHOW THE
GREATEST ENHANCEMENT AND COLDEST CLOUD TOPS MOVING ACROSS NE UTAH
AND NW COLORADO AS OF 09Z...WHICH INDICATES THE CURRENT POSITION OF
THE JET STREAK. THE TREND OVER THE LAST FEW HOURS HAS BEEN A BRIEF
ENHANCEMENT AND QUICK DROP OFF ON IR SATELLITE. SNOTEL OBSERVATIONS
IN THE MOUNTAINS DO NOT INDICATE THAT MUCH HAS FALLEN YET BUT LOOKS
LIKE THE BEST FORCING AND CHANCE FOR SHOWERS ARRIVE WITH THE JET
STREAK BETWEEN 09Z AND 15Z...WITH A PEAK AROUND 12Z OR SUNRISE. THE
NAM IS MUCH WEAKER AND PRODUCES MUCH LESS PRECIP. THE 00Z NAM
FAVORED THE CENTRAL MTNS BUT AS SOON AS THE 06Z RUN CAME IN...THE
FOCUS SHIFTED BACK TO THE NORTHERN MTNS. THE 00Z GFS SHOWED MORE
WIDESPREAD PRECIP AFFECTING THE NORTHERN AND CENTRAL MTNS AND SEEMED
6 HRS FASTER THAN THE NAM. TEMPERATURES ARE GENERALLY ABOVE
FREEZING FOR MOST OF THE NORTHERN AND CENTRAL VALLEYS.
WITH THE TREND OF THE LAST FEW SYSTEMS WEAKENING AS THEY APPROACH
AND GRADUAL WEAKENING BY THE MODELS WITH THIS DISTURBANCE...LEANED
TOWARDS LESSER AMTS THAN PREVIOUSLY THOUGHT. ROUGHLY 2 TO 4 INCHES
OF SNOW IS EXPECTED OVER THE NORTHERN AND CENTRAL CO MTNS WITH THE
FLATTOPS SEEING THE BEST ACCUMS AT 3 TO 5 INCHES. SAN JUANS MAY SEE
AN INCH OR TWO BUT THE FOCUS LOOKS TO BE MORE OVER THE NORTHERN AND
CENTRAL MTNS WHERE THE JET STREAK ON SATELLITE LOOKS TO TRACK OVER.
TEMPERATURES STAY TOO MILD AND FORCING AND OROGRAPHICS APPEAR TOO
WEAK TO WARRANT ANY HIGHLIGHTS AS AMTS LOOK TO STAY BELOW ADVISORY
CRITERIA. LOWER VALLEYS WILL SEE A SLIGHT CHANCE OF RAIN SHOWERS
WITH SOME HIGHER NORTHERN VALLEYS MIXING IN AT TIMES WITH SNOW AS
THE JET STREAK MOVES THROUGH. HOWEVER LITTLE ACCUMULATION IS
EXPECTED FOR VALLEYS WITH GROUND BEING TOO WARM.
THE REST OF THE AFTERNOON INTO THE EVENING WILL SEE PERIODS OF
OROGRAPHIC SNOW SHOWERS LIMITED TO THE HIGHER TERRAIN ALONG THE
DIVIDE AS A MOIST WESTERLY FLOW REMAINS...ALBEIT WEAK. ANY SNOW
WILL BE FAIRLY LIGHT THOUGH WITH LITTLE ADDITIONAL ACCUMULATIONS.
THE REST OF THE FORECAST AREA WILL SEE PERIODS OF SUN AND CLOUDS AS
WE GRADUALLY DRY OUT FROM THE WEST. SOME MOISTURE WILL LINGER
ACROSS THE NORTHERN CO MTNS FRIDAY FOR SOME LIGHT OROGRAPHIC SNOW
SHOWERS THERE. THE BIG STORY HERE WILL BE THE MUCH COLDER
TEMPERATURES FELT AS A COLDER AIR MASS FILTERS IN. MORE ON THIS
PATTERN CHANGE BELOW.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 409 AM MST THU DEC 6 2012
A BROAD OPEN TROUGH WILL PERSIST OVER THE NORTHWESTERN U.S. FRIDAY
NIGHT WITH MOISTURE ENTRAINED IN NORTHWESTERLIES CONTINUING TO
BRING PERIODS OF LIGHT SNOW TO THE NORTHERN MOUNTAINS. AS ALLUDED
TO ABOVE AND MENTIONED IN THE PREVIOUS DISCUSSION...A PATTERN
CHANGE BEGINS THIS WEEKEND WHICH WILL FEATURE HIGH PRESSURE OVER
THE EASTERN PACIFIC AND A BROAD TROUGH OVER THE CENTRAL U.S.
THIS SHIFT FIRST BECOMES APPARENT EARLY SATURDAY AS THE POLAR JET
DIGS SOUTHWARD ACROSS THE PACIFIC NORTHWEST DRIVING A COLD FRONT
INTO NORTHERN COLORADO. QG FORCING COMBINED WITH OROGRAPHIC LIFT
PROVIDED BY STRONG WESTERLIES AND AN INCREASINGLY SATURATED
DENDRITIC GROWTH REGION WILL BRING MEASURABLE SNOW TO THE NORTHERN
MOUNTAINS...MAINLY DURING THE AFTERNOON. AS THE FRONT AND THE
UPPER LEVEL FORCING CONTINUES TO SWEEP SOUTHWARD SATURDAY NIGHT
INTO SUNDAY MORNING SNOW WILL CONTINUE TO SPREAD SOUTH. COLDER AIR
MOVING IN BEHIND THE FRONT WILL BRING SNOW LEVELS TO VALLEY
BOTTOMS. AS THE TROUGH AXIS SHIFTS EAST OF THE DIVIDE AROUND
MIDDAY SNOW WILL DECREASE OVER THE MOUNTAINS. TENTATIVE SNOW
ACCUMULATIONS FOR THE NORTHERN AND CENTRAL COLORADO MOUNTAINS LOOK
TO BE ON THE ORDER OF 4 TO 8 INCHES WITH LOCALLY HIGHER AMOUNTS.
COMBINED WITH SOME BLOWING SNOW...THERE IS A POSSIBILITY FOR
WINTER WEATHER ADVISORIES THIS WEEKEND. LESSER ACCUMULATIONS ARE
EXPECTED IN THE SOUTHERN MOUNTAINS.
MOISTURE IN THE NORTHWESTERLIES WILL BEGIN TO BRING SNOW TO THE
REGION AGAIN MONDAY WITH THE GFS ABOUT 6 HOURS FASTER THAN THE
ECMWF WITH THE ONSET OF PRECIPITATION. BOTH MODELS MENTIONED
GENERATE PERSISTENT QPF OVER THE NORTHERN AND CENTRAL MOUNTAINS
THROUGH WEDNESDAY EVENING WITH A DISCERNIBLE SHORTWAVE MOVING
ACROSS THE REGION TUESDAY AFTERNOON. DIFFICULT TO PIN DOWN
ACCUMULATIONS THIS FAR OUT...BUT MODERATE ACCUMULATIONS SEEM
LIKELY AT THIS POINT. HOWEVER...APPEARS THE SOUTHERN MOUNTAINS
WILL REMAIN ON THE OUTSIDE LOOKING IN WITH RESPECT TO ANY
APPRECIABLE SNOWFALL. APPEARS WEDNESDAY WILL BE BETWEEN SYSTEMS
WITH YET ANOTHER SYSTEM POISED TO MOVE THROUGH THE AREA DURING THE
NIGHT.
UNSEASONABLY MILD TEMPERATURES WILL COME TO AN END THIS WEEKEND AS
7H TEMPS COOL TO NEAR -18 DEGS C ACROSS THE NORTH IN THE WAKE OF
THE FRONT SUNDAY MORNING. AS A RESULT...TEMPERATURES WILL DIP TO 5
TO 10 DEGREES BELOW NORMAL SUNDAY BEFORE GRADUALLY RECOVERING TO
NEAR NORMAL BY MIDWEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1044 AM MST THU DEC 6 2012
MOIST WESTERLY FLOW BRINGING MIXED PRECIPITATION TO THE REGION
LATE THIS MORNING WITH SNOW IN THE HIGH COUNTRY AND RAIN AT THE
LOWER ELEVATIONS...EXCEPT GUNNISON AREA WHERE SNOW HAS BEEN THE
PREDOMINATE P-TYPE. MANY MOUNTAINS AND HIGH PASSES IN COLORAO
REMAIN OBSCURED AS THE JET AND FAVORABLE DYNAMICS MOVE OVERHEAD.
HOWEVER MOST FLIGHT TERMINALS OUTSIDE KASE ARE AT VFR LEVELS AND
THIS TREND SHOULD CONTINUE THE NEXT 24 HOURS. AT KASE LOWER CIGS
AND SOME PASSING SHOWERS WILL CONTINUE THROUGH 06/20Z THEN AS
DRIER AIR MOVES IN ALOFT...IMPROVEMENT IS EXPECTED. CLEARING WILL
CONTINUE SOUTHWARD THROUGH THE EVENING AND MOUNTAIN OBSCURATIONS
SHOULD CLEAR. LATE ARRIVING MOISTURE OVERNIGHT WILL AGAIN BRING IN
LOWERING CLOUD HEIGHTS TO THE NORTHERN AND CENTRAL MOUNTAINS WHERE
OBSCURATIONS WILL ONCE AGAIN BE POSSIBLE WITH LIGHT SNOW MOVING
THROUGH AS WELL.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
UPDATE...15
SHORT TERM...MDA
LONG TERM...NL
AVIATION...15
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
829 AM MST THU DEC 6 2012
.UPDATE...
ISSUED AT 829 AM MST THU DEC 6 2012
HAVE ADJUSTED POPS UPWARD ACROSS THE SOUTHERN MOUNTAINS AND VALLEY
LOCATIONS LOOKING AT THE LATEST RADAR...SATELLITE AND WEB CAM
TRENDS. NEWEST NAM MODEL IS ALSO TRENDING THIS WAY SHOWING THE
MOISTURE TAP SEEN IN THE GOES DERIVED IMAGERY NOSING ACROSS THE 4
CORNERS REGION ALONG WITH SOME JET DYNAMICS. EPV FIELDS AND RADAR
PICS ALSO SHOW THIS AREA IS MORE CONVECTIVE IN NATURE SO SOME
QUICK BURSTS OF SNOWFALL MAY OCCUR AT THE HIGHER ELEVATIONS.
FARTHER NORTH...MOIST WESTERLY FLOW WILL CONTINUE TO BRING
SNOWFALL TO THE NORTHERN AND CENTRAL MOUNTAINS AND ADJACENT HIGHER
VALLEYS THIS MORNING...BUT THE DENDRITIC LAYER LOOKS TO BE DRYING
OUT THROUGH THE AFTERNOON. WILL CONTINUE TO MONITOR TRENDS FOR
ADDITIONAL UPDATES.
&&
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 409 AM MST THU DEC 6 2012
SHORT-TERM MODELS ARE STILL HAVING A TOUGH TIME DECIDING WHAT THEY
WANT TO DO IN TERMS OF THE DISTURBANCE MOVING THROUGH EARLY THIS
MORNING THROUGH THE AFTERNOON. THE NAM AND RAP ARE THE LEAST
IMPRESSIVE WITH THIS SYSTEM WITH FAR LESS SNOW AMOUNTS THAN THE
GFS. DESPITE THE DIFFERENCE IN SNOW AMTS BETWEEN MODELS...THE
CONSISTENT THING IS THAT 700MB TEMPS ARE AROUND -3C IN THE NORTHERN
MTNS WITH -1C IN THE CENTRAL MTNS. THIS PUTS SNOW LEVELS AT AROUND
7 OR 8 KFT. 700MB WINDS ARE BETWEEN 5 AND 10 KTS...FAR LESS THAN
THEY WERE 24 HRS AGO. THIS DOES NOT FAVOR STRONG UPSLOPE FLOW OR
STRONG OROGRAPHIC EVENT. THE BULK OF THE PRECIP LOOKS TO OCCUR WITH
THE UPPER LEVEL JET STREAK THAT IS SET TO MOVE THROUGH THIS MORNING
BETWEEN 09Z AND 15Z ACCORDING TO TIME HEIGHTS. CURRENT OBSERVATIONS
AS OF 09Z SHOW SOME LIGHT SNOW FALLING OVER MT WERNER NEAR SBS AND
SOME BRIEF LIGHT SNOW IN THE ASPEN AREA THIS PAST EVENING. LIGHT
RAIN JUST STARTED IN CRAIG AS WELL. SATELLITE TRENDS SHOW THE
GREATEST ENHANCEMENT AND COLDEST CLOUD TOPS MOVING ACROSS NE UTAH
AND NW COLORADO AS OF 09Z...WHICH INDICATES THE CURRENT POSITION OF
THE JET STREAK. THE TREND OVER THE LAST FEW HOURS HAS BEEN A BRIEF
ENHANCEMENT AND QUICK DROP OFF ON IR SATELLITE. SNOTEL OBSERVATIONS
IN THE MOUNTAINS DO NOT INDICATE THAT MUCH HAS FALLEN YET BUT LOOKS
LIKE THE BEST FORCING AND CHANCE FOR SHOWERS ARRIVE WITH THE JET
STREAK BETWEEN 09Z AND 15Z...WITH A PEAK AROUND 12Z OR SUNRISE. THE
NAM IS MUCH WEAKER AND PRODUCES MUCH LESS PRECIP. THE 00Z NAM
FAVORED THE CENTRAL MTNS BUT AS SOON AS THE 06Z RUN CAME IN...THE
FOCUS SHIFTED BACK TO THE NORTHERN MTNS. THE 00Z GFS SHOWED MORE
WIDESPREAD PRECIP AFFECTING THE NORTHERN AND CENTRAL MTNS AND SEEMED
6 HRS FASTER THAN THE NAM. TEMPERATURES ARE GENERALLY ABOVE
FREEZING FOR MOST OF THE NORTHERN AND CENTRAL VALLEYS.
WITH THE TREND OF THE LAST FEW SYSTEMS WEAKENING AS THEY APPROACH
AND GRADUAL WEAKENING BY THE MODELS WITH THIS DISTURBANCE...LEANED
TOWARDS LESSER AMTS THAN PREVIOUSLY THOUGHT. ROUGHLY 2 TO 4 INCHES
OF SNOW IS EXPECTED OVER THE NORTHERN AND CENTRAL CO MTNS WITH THE
FLATTOPS SEEING THE BEST ACCUMS AT 3 TO 5 INCHES. SAN JUANS MAY SEE
AN INCH OR TWO BUT THE FOCUS LOOKS TO BE MORE OVER THE NORTHERN AND
CENTRAL MTNS WHERE THE JET STREAK ON SATELLITE LOOKS TO TRACK OVER.
TEMPERATURES STAY TOO MILD AND FORCING AND OROGRAPHICS APPEAR TOO
WEAK TO WARRANT ANY HIGHLIGHTS AS AMTS LOOK TO STAY BELOW ADVISORY
CRITERIA. LOWER VALLEYS WILL SEE A SLIGHT CHANCE OF RAIN SHOWERS
WITH SOME HIGHER NORTHERN VALLEYS MIXING IN AT TIMES WITH SNOW AS
THE JET STREAK MOVES THROUGH. HOWEVER LITTLE ACCUMULATION IS
EXPECTED FOR VALLEYS WITH GROUND BEING TOO WARM.
THE REST OF THE AFTERNOON INTO THE EVENING WILL SEE PERIODS OF
OROGRAPHIC SNOW SHOWERS LIMITED TO THE HIGHER TERRAIN ALONG THE
DIVIDE AS A MOIST WESTERLY FLOW REMAINS...ALBEIT WEAK. ANY SNOW
WILL BE FAIRLY LIGHT THOUGH WITH LITTLE ADDITIONAL ACCUMULATIONS.
THE REST OF THE FORECAST AREA WILL SEE PERIODS OF SUN AND CLOUDS AS
WE GRADUALLY DRY OUT FROM THE WEST. SOME MOISTURE WILL LINGER
ACROSS THE NORTHERN CO MTNS FRIDAY FOR SOME LIGHT OROGRAPHIC SNOW
SHOWERS THERE. THE BIG STORY HERE WILL BE THE MUCH COLDER
TEMPERATURES FELT AS A COLDER AIR MASS FILTERS IN. MORE ON THIS
PATTERN CHANGE BELOW.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 409 AM MST THU DEC 6 2012
A BROAD OPEN TROUGH WILL PERSIST OVER THE NORTHWESTERN U.S. FRIDAY
NIGHT WITH MOISTURE ENTRAINED IN NORTHWESTERLIES CONTINUING TO
BRING PERIODS OF LIGHT SNOW TO THE NORTHERN MOUNTAINS. AS ALLUDED
TO ABOVE AND MENTIONED IN THE PREVIOUS DISCUSSION...A PATTERN
CHANGE BEGINS THIS WEEKEND WHICH WILL FEATURE HIGH PRESSURE OVER
THE EASTERN PACIFIC AND A BROAD TROUGH OVER THE CENTRAL U.S.
THIS SHIFT FIRST BECOMES APPARENT EARLY SATURDAY AS THE POLAR JET
DIGS SOUTHWARD ACROSS THE PACIFIC NORTHWEST DRIVING A COLD FRONT
INTO NORTHERN COLORADO. QG FORCING COMBINED WITH OROGRAPHIC LIFT
PROVIDED BY STRONG WESTERLIES AND AN INCREASINGLY SATURATED
DENDRITIC GROWTH REGION WILL BRING MEASURABLE SNOW TO THE NORTHERN
MOUNTAINS...MAINLY DURING THE AFTERNOON. AS THE FRONT AND THE
UPPER LEVEL FORCING CONTINUES TO SWEEP SOUTHWARD SATURDAY NIGHT
INTO SUNDAY MORNING SNOW WILL CONTINUE TO SPREAD SOUTH. COLDER AIR
MOVING IN BEHIND THE FRONT WILL BRING SNOW LEVELS TO VALLEY
BOTTOMS. AS THE TROUGH AXIS SHIFTS EAST OF THE DIVIDE AROUND
MIDDAY SNOW WILL DECREASE OVER THE MOUNTAINS. TENTATIVE SNOW
ACCUMULATIONS FOR THE NORTHERN AND CENTRAL COLORADO MOUNTAINS LOOK
TO BE ON THE ORDER OF 4 TO 8 INCHES WITH LOCALLY HIGHER AMOUNTS.
COMBINED WITH SOME BLOWING SNOW...THERE IS A POSSIBILITY FOR
WINTER WEATHER ADVISORIES THIS WEEKEND. LESSER ACCUMULATIONS ARE
EXPECTED IN THE SOUTHERN MOUNTAINS.
MOISTURE IN THE NORTHWESTERLIES WILL BEGIN TO BRING SNOW TO THE
REGION AGAIN MONDAY WITH THE GFS ABOUT 6 HOURS FASTER THAN THE
ECMWF WITH THE ONSET OF PRECIPITATION. BOTH MODELS MENTIONED
GENERATE PERSISTENT QPF OVER THE NORTHERN AND CENTRAL MOUNTAINS
THROUGH WEDNESDAY EVENING WITH A DISCERNIBLE SHORTWAVE MOVING
ACROSS THE REGION TUESDAY AFTERNOON. DIFFICULT TO PIN DOWN
ACCUMULATIONS THIS FAR OUT...BUT MODERATE ACCUMULATIONS SEEM
LIKELY AT THIS POINT. HOWEVER...APPEARS THE SOUTHERN MOUNTAINS
WILL REMAIN ON THE OUTSIDE LOOKING IN WITH RESPECT TO ANY
APPRECIABLE SNOWFALL. APPEARS WEDNESDAY WILL BE BETWEEN SYSTEMS
WITH YET ANOTHER SYSTEM POISED TO MOVE THROUGH THE AREA DURING THE
NIGHT.
UNSEASONABLY MILD TEMPERATURES WILL COME TO AN END THIS WEEKEND AS
7H TEMPS COOL TO NEAR -18 DEGS C ACROSS THE NORTH IN THE WAKE OF
THE FRONT SUNDAY MORNING. AS A RESULT...TEMPERATURES WILL DIP TO 5
TO 10 DEGREES BELOW NORMAL SUNDAY BEFORE GRADUALLY RECOVERING TO
NEAR NORMAL BY MIDWEEK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 409 AM MST THU DEC 6 2012
VFR CONDITIONS CONTINUE AT MOST TAF SITES WITH OVERCAST SKIES AND
LOWERING CLOUD HEIGHTS. AS THE DISTURBANCE CURRENTLY OVER NE
UTAH AND NW COLORADO MOVES THROUGH...CIGS AND VIS WILL DROP WITH
MVFR CONDITIONS FOR KCAG...KHDN...AND KSBS UNDER LIGHT SHOWERS.
SOME IFR CONDITIONS MAY OCCUR UNDER HEAVIER SNOW/RAIN SHOWERS OVER
THE NORTHERN AND CENTRAL COLORADO MOUNTAINS UNTIL 15Z. THIS
INCLUDES KASE AND KEGE. SHOWERS WILL LINGER THROUGH 18Z WITH MVFR
CONDITIONS BEFORE IMPROVING TO VFR AS DRIER AIR MOVES IN FROM THE
WEST. SHOWERS WILL BE CONFINED TO HIGHER MOUNTAIN SITES AFTER 18Z
TODAY THROUGH FRIDAY MORNING ALONG THE DIVIDE...INCLUDING KASE...
KEGE...AND KSBS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
UPDATE...15
SHORT TERM...MDA
LONG TERM...NL
AVIATION...MDA
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
410 AM MST THU DEC 6 2012
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 409 AM MST THU DEC 6 2012
SHORT-TERM MODELS ARE STILL HAVING A TOUGH TIME DECIDING WHAT THEY
WANT TO DO IN TERMS OF THE DISTURBANCE MOVING THROUGH EARLY THIS
MORNING THROUGH THE AFTERNOON. THE NAM AND RAP ARE THE LEAST
IMPRESSIVE WITH THIS SYSTEM WITH FAR LESS SNOW AMOUNTS THAN THE
GFS. DESPITE THE DIFFERENCE IN SNOW AMTS BETWEEN MODELS...THE
CONSISTENT THING IS THAT 700MB TEMPS ARE AROUND -3C IN THE NORTHERN
MTNS WITH -1C IN THE CENTRAL MTNS. THIS PUTS SNOW LEVELS AT AROUND
7 OR 8 KFT. 700MB WINDS ARE BETWEEN 5 AND 10 KTS...FAR LESS THAN
THEY WERE 24 HRS AGO. THIS DOES NOT FAVOR STRONG UPSLOPE FLOW OR
STRONG OROGRAPHIC EVENT. THE BULK OF THE PRECIP LOOKS TO OCCUR WITH
THE UPPER LEVEL JET STREAK THAT IS SET TO MOVE THROUGH THIS MORNING
BETWEEN 09Z AND 15Z ACCORDING TO TIME HEIGHTS. CURRENT OBSERVATIONS
AS OF 09Z SHOW SOME LIGHT SNOW FALLING OVER MT WERNER NEAR SBS AND
SOME BRIEF LIGHT SNOW IN THE ASPEN AREA THIS PAST EVENING. LIGHT
RAIN JUST STARTED IN CRAIG AS WELL. SATELLITE TRENDS SHOW THE
GREATEST ENHANCEMENT AND COLDEST CLOUD TOPS MOVING ACROSS NE UTAH
AND NW COLORADO AS OF 09Z...WHICH INDICATES THE CURRENT POSITION OF
THE JET STREAK. THE TREND OVER THE LAST FEW HOURS HAS BEEN A BRIEF
ENHANCEMENT AND QUICK DROP OFF ON IR SATELLITE. SNOTEL OBSERVATIONS
IN THE MOUNTAINS DO NOT INDICATE THAT MUCH HAS FALLEN YET BUT LOOKS
LIKE THE BEST FORCING AND CHANCE FOR SHOWERS ARRIVE WITH THE JET
STREAK BETWEEN 09Z AND 15Z...WITH A PEAK AROUND 12Z OR SUNRISE. THE
NAM IS MUCH WEAKER AND PRODUCES MUCH LESS PRECIP. THE 00Z NAM
FAVORED THE CENTRAL MTNS BUT AS SOON AS THE 06Z RUN CAME IN...THE
FOCUS SHIFTED BACK TO THE NORTHERN MTNS. THE 00Z GFS SHOWED MORE
WIDESPREAD PRECIP AFFECTING THE NORTHERN AND CENTRAL MTNS AND SEEMED
6 HRS FASTER THAN THE NAM. TEMPERATURES ARE GENERALLY ABOVE
FREEZING FOR MOST OF THE NORTHERN AND CENTRAL VALLEYS.
WITH THE TREND OF THE LAST FEW SYSTEMS WEAKENING AS THEY APPROACH
AND GRADUAL WEAKENING BY THE MODELS WITH THIS DISTURBANCE...LEANED
TOWARDS LESSER AMTS THAN PREVIOUSLY THOUGHT. ROUGHLY 2 TO 4 INCHES
OF SNOW IS EXPECTED OVER THE NORTHERN AND CENTRAL CO MTNS WITH THE
FLATTOPS SEEING THE BEST ACCUMS AT 3 TO 5 INCHES. SAN JUANS MAY SEE
AN INCH OR TWO BUT THE FOCUS LOOKS TO BE MORE OVER THE NORTHERN AND
CENTRAL MTNS WHERE THE JET STREAK ON SATELLITE LOOKS TO TRACK OVER.
TEMPERATURES STAY TOO MILD AND FORCING AND OROGRAPHICS APPEAR TOO
WEAK TO WARRANT ANY HIGHLIGHTS AS AMTS LOOK TO STAY BELOW ADVISORY
CRITERIA. LOWER VALLEYS WILL SEE A SLIGHT CHANCE OF RAIN SHOWERS
WITH SOME HIGHER NORTHERN VALLEYS MIXING IN AT TIMES WITH SNOW AS
THE JET STREAK MOVES THROUGH. HOWEVER LITTLE ACCUMULATION IS
EXPECTED FOR VALLEYS WITH GROUND BEING TOO WARM.
THE REST OF THE AFTERNOON INTO THE EVENING WILL SEE PERIODS OF
OROGRAPHIC SNOW SHOWERS LIMITED TO THE HIGHER TERRAIN ALONG THE
DIVIDE AS A MOIST WESTERLY FLOW REMAINS...ALBEIT WEAK. ANY SNOW
WILL BE FAIRLY LIGHT THOUGH WITH LITTLE ADDITIONAL ACCUMULATIONS.
THE REST OF THE FORECAST AREA WILL SEE PERIODS OF SUN AND CLOUDS AS
WE GRADUALLY DRY OUT FROM THE WEST. SOME MOISTURE WILL LINGER
ACROSS THE NORTHERN CO MTNS FRIDAY FOR SOME LIGHT OROGRAPHIC SNOW
SHOWERS THERE. THE BIG STORY HERE WILL BE THE MUCH COLDER
TEMPERATURES FELT AS A COLDER AIR MASS FILTERS IN. MORE ON THIS
PATTERN CHANGE BELOW.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 409 AM MST THU DEC 6 2012
A BROAD OPEN TROUGH WILL PERSIST OVER THE NORTHWESTERN U.S. FRIDAY
NIGHT WITH MOISTURE ENTRAINED IN NORTHWESTERLIES CONTINUING TO
BRING PERIODS OF LIGHT SNOW TO THE NORTHERN MOUNTAINS. AS ALLUDED
TO ABOVE AND MENTIONED IN THE PREVIOUS DISCUSSION...A PATTERN
CHANGE BEGINS THIS WEEKEND WHICH WILL FEATURE HIGH PRESSURE OVER
THE EASTERN PACIFIC AND A BROAD TROUGH OVER THE CENTRAL U.S.
THIS SHIFT FIRST BECOMES APPARENT EARLY SATURDAY AS THE POLAR JET
DIGS SOUTHWARD ACROSS THE PACIFIC NORTHWEST DRIVING A COLD FRONT
INTO NORTHERN COLORADO. QG FORCING COMBINED WITH OROGRAPHIC LIFT
PROVIDED BY STRONG WESTERLIES AND AN INCREASINGLY SATURATED
DENDRITIC GROWTH REGION WILL BRING MEASURABLE SNOW TO THE NORTHERN
MOUNTAINS...MAINLY DURING THE AFTERNOON. AS THE FRONT AND THE
UPPER LEVEL FORCING CONTINUES TO SWEEP SOUTHWARD SATURDAY NIGHT
INTO SUNDAY MORNING SNOW WILL CONTINUE TO SPREAD SOUTH. COLDER AIR
MOVING IN BEHIND THE FRONT WILL BRING SNOW LEVELS TO VALLEY
BOTTOMS. AS THE TROUGH AXIS SHIFTS EAST OF THE DIVIDE AROUND
MIDDAY SNOW WILL DECREASE OVER THE MOUNTAINS. TENTATIVE SNOW
ACCUMULATIONS FOR THE NORTHERN AND CENTRAL COLORADO MOUNTAINS LOOK
TO BE ON THE ORDER OF 4 TO 8 INCHES WITH LOCALLY HIGHER AMOUNTS.
COMBINED WITH SOME BLOWING SNOW...THERE IS A POSSIBILITY FOR
WINTER WEATHER ADVISORIES THIS WEEKEND. LESSER ACCUMULATIONS ARE
EXPECTED IN THE SOUTHERN MOUNTAINS.
MOISTURE IN THE NORTHWESTERLIES WILL BEGIN TO BRING SNOW TO THE
REGION AGAIN MONDAY WITH THE GFS ABOUT 6 HOURS FASTER THAN THE
ECMWF WITH THE ONSET OF PRECIPITATION. BOTH MODELS MENTIONED
GENERATE PERSISTENT QPF OVER THE NORTHERN AND CENTRAL MOUNTAINS
THROUGH WEDNESDAY EVENING WITH A DISCERNIBLE SHORTWAVE MOVING
ACROSS THE REGION TUESDAY AFTERNOON. DIFFICULT TO PIN DOWN
ACCUMULATIONS THIS FAR OUT...BUT MODERATE ACCUMULATIONS SEEM
LIKELY AT THIS POINT. HOWEVER...APPEARS THE SOUTHERN MOUNTAINS
WILL REMAIN ON THE OUTSIDE LOOKING IN WITH RESPECT TO ANY
APPRECIABLE SNOWFALL. APPEARS WEDNESDAY WILL BE BETWEEN SYSTEMS
WITH YET ANOTHER SYSTEM POISED TO MOVE THROUGH THE AREA DURING THE
NIGHT.
UNSEASONABLY MILD TEMPERATURES WILL COME TO AN END THIS WEEKEND AS
7H TEMPS COOL TO NEAR -18 DEGS C ACROSS THE NORTH IN THE WAKE OF
THE FRONT SUNDAY MORNING. AS A RESULT...TEMPERATURES WILL DIP TO 5
TO 10 DEGREES BELOW NORMAL SUNDAY BEFORE GRADUALLY RECOVERING TO
NEAR NORMAL BY MIDWEEK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 409 AM MST THU DEC 6 2012
VFR CONDITIONS CONTINUE AT MOST TAF SITES WITH OVERCAST SKIES AND
LOWERING CLOUD HEIGHTS. AS THE DISTURBANCE CURRENTLY OVER NE
UTAH AND NW COLORADO MOVES THROUGH...CIGS AND VIS WILL DROP WITH
MVFR CONDITIONS FOR KCAG...KHDN...AND KSBS UNDER LIGHT SHOWERS.
SOME IFR CONDITIONS MAY OCCUR UNDER HEAVIER SNOW/RAIN SHOWERS OVER
THE NORTHERN AND CENTRAL COLORADO MOUNTAINS UNTIL 15Z. THIS
INCLUDES KASE AND KEGE. SHOWERS WILL LINGER THROUGH 18Z WITH MVFR
CONDITIONS BEFORE IMPROVING TO VFR AS DRIER AIR MOVES IN FROM THE
WEST. SHOWERS WILL BE CONFINED TO HIGHER MOUNTAIN SITES AFTER 18Z
TODAY THROUGH FRIDAY MORNING ALONG THE DIVIDE...INCLUDING KASE...
KEGE...AND KSBS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...MDA
LONG TERM...NL
AVIATION...MDA
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
300 AM EST THU DEC 6 2012
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS THE TROUGH FRACTURE
UNDERWAY LAST NIGHT HAS COMPLETED WITH THE MAIN LONG WAVE TROUGH NOW
EJECTING EASTWARD FROM THE NEW ENGLAND/MID ATLANTIC COAST...AND THE
SHORTWAVE ENERGY LEFT BEHIND TRANSLATING EASTWARD OVER THE GULF OF
MEXICO. THIS SHORTWAVE IS CURRENTLY VERY IMPRESSIVE IN APPEARANCE
WITH A WELL-DEFINED SPIN OFF THE MS DELTA AND STRONG SYNOPTIC LIFT
SUPPORTING FAIRLY VIGOROUS CONVECTION ON ITS EASTERN SIDE. THE
GLOBAL MODELS UNDER-ESTIMATED THE SHARPNESS OF THIS TROUGH IN
PREVIOUS RUNS. IN FACT...THE HEIGHT FALLS WERE SIGNIFICANT ENOUGH TO
OUR WEST ON WEDNESDAY...THAT IT ACTED TO HOLD THE RIDGE IN PLACE
LONGER THAN WAS EXPECTED OVER THE PENINSULA. THE 06/00Z KTBW
SOUNDING PROFILE SHOWED THIS EFFECT WITH A STUBBORN SUBSIDENCE
INVERSION STILL IN PLACE AROUND 800MB. TIME IS NOW UP FOR THIS RIDGE
EITHER WAY AS HEIGHT FALLS HAVE COMMENCED. ELSEWHERE ACROSS THE
CONUS... NORTHERN STREAM FLOW IS RATHER UNAMPLIFIED ONCE THE TROUGH
EXITS THE NORTHEASTERN STATES. THIS FAST ZONAL FLOW WILL HOLD FOR A
COUPLE MORE DAYS BEFORE THE NEXT SIGNIFICANT AMPLIFICATION TO THE
PATTERN OCCURS OVER THE UPCOMING WEEKEND.
AT THE SURFACE...SURFACE RIDGE TO OUR NORTH CONTINUES TO WEAKEN AND
IS BECOMING RATHER ILL-DEFINED EARLY THIS MORNING. FORECAST AREA IS
NOW WITHIN A WEAK GRADIENT BETWEEN AN INVERTED SURFACE TROUGH JUST
OFF THE FLORIDA EAST COAST...AND A PROBABLE WEAK SURFACE
LOW/REFLECTION OVER THE NORTH-CENTRAL GULF UNDERNEATH THE PARENT
SHORTWAVE. NOT A WHOLE LOT OF ACTION CURRENTLY ON REGIONAL RADARS
BESIDES A FEW CONVECTIVE CELLS OVER THE GULF STREAM ASSOCIATED WITH
THE LOW LEVEL FOCUS OF THE SURFACE TROUGH.
&&
.SHORT TERM (TODAY - SATURDAY)...
TODAY...SHORTWAVE WILL MIGRATE TOWARD...AND ARRIVE OVER OUR FORECAST
AREA. HOWEVER...GLOBAL GUIDANCE SHOWS THE CURRENT POTENCY OF THIS
SHORTWAVE WILL NOT LAST AS A GRADUAL SHEARING OUT OF THE ENERGY IS
EXPECTED DURING THE NEXT 24 HOURS. EVEN SO...SYNOPTIC SUPPORT FOR
LIFT WILL BE SUFFICIENT ENOUGH FOR WIDELY SCT TO SCT SHOWERS AND
POSSIBLY A RUMBLE OF THUNDER. THE PATH OF THE SHORTWAVE DELIVERS THE
BEST QG FORCING TO THE SOUTHERN HALF OF THE FORECAST AREA THIS
MORNING THROUGH MID AFTERNOON BEFORE THIS FOCUS/LIFT BEGINS TO EXIT
TO OUR EAST. THE APPROACH OF THE SHORTWAVE WILL ALSO ACT TO SHARPEN
THE INVERTED SURFACE TROUGH ALONG/JUST OFF THE FL EAST COAST. THIS
SHARPENING TROUGH SHOULD ACT TO FOCUS MORE ORGANIZED SHOWER ACTIVITY
ALONG THE EAST COAST...SOME OF WHICH WILL MIGRATE BACK WEST AND
NORTHWEST TOWARD US. ALL OF THIS SUGGESTS THE BEST SHOWER CHANCES
(35-45%) WILL EXIST SOUTH OF THE I-4 CORRIDOR. FURTHER NORTH THE
ACTIVITY IS EXPECTED TO BE MORE WIDELY SCT IN NATURE...SO WENT WITH
A GENERAL (20-30%) POP FOR THESE ZONES. DID ADD MENTION OF ISOLATED
THUNDER FOR THE SOUTHERN COASTAL WATERS AND ALSO DOWN TOWARD
LEE/CHARLOTTE COUNTIES WHERE SHOWALTER INDICES ARE AROUND ZERO.
LOCAL AND NATIONAL HIRES CONVECTIVE ALLOWING GUIDANCE ALSO SHOW THE
BEST UPDRAFT POTENTIAL OVER THESE SOUTHERN ZONES.
TONIGHT/FRIDAY...SHORTWAVE ENERGY MOVES EAST OF THE AREA WITH WEAK
SUPPRESSION ATTEMPTING TO BUILD OVERHEAD IN ITS WAKE. BEST SHOWER
CHANCES DURING THE PERIOD WILL EXIST ALONG THE FLORIDA EAST COAST
WHERE THE CONTINUED LOW LEVEL FOCUS FROM THE SURFACE TROUGH WILL
REMAIN IN PLACE. THERE ARE SOME INDICATIONS THAT THIS TROUGH AXIS
WILL RETROGRADE WESTWARD A BIT DURING THE DAY...AND IF THIS OCCURS
WE COULD SEE A FEW ISOLATED SHOWERS RE-DEVELOPING ACROSS OUR
INTERIOR ZONES FRIDAY AFTERNOON. OTHER THAN THE FEW ISOLATED
SHOWERS...FRIDAY`S MAIN FORECAST LOOKS TO BE A MIX OF SUN AND CLOUDS
AND ABOVE NORMAL TEMPERATURES. 850MB TEMPS OF 12-13C SHOULD YIELD
HIGH TEMPS IN THE UPPER 70S TO NEAR 80 WITH EVEN A MODEST AMOUNT OF
SOLAR INSOLATION.
SATURDAY...SIMILAR CONDITIONS TO FRIDAY ANTICIPATED FOR THE FIRST
HALF OF THE WEEKEND. SURFACE RIDGE AXIS WILL BE ALIGNED TO THE NORTH
OF THE I-10 CORRIDOR WITH A WEAK INVERTED TROUGH/WEAKNESS IN THE
RIDGE OVER THE CENTRAL/SOUTHERN FL PENINSULA. SHOULD BE JUST ENOUGH
FOCUS ALONG THIS TROUGH AND ENOUGH DIURNAL INSTABILITY TO SUPPORT
ISOLATED SHOWERS...BUT OTHERWISE THE FORECAST WILL SHOW A MIX OF SUN
AND CLOUDS AND TEMPS BETWEEN 79-83. THE LOCAL GRADIENT WILL BE WEAK
AND POSSIBLY ALLOW A FEEBLE SEA-BREEZE NEAR THE COAST IN THE
AFTERNOON. ANY SEABREEZE WOULD KEEP HIGH TEMPS ALONG THE IMMEDIATE
COAST DOWN A FEW DEGREES AS AIR MOVES ONSHORE FROM THE NOW
RELATIVELY COOLER SHELF WATERS.
&&
.LONG TERM (SUNDAY - NEXT WEDNESDAY)...
MODELS CONTINUE TO STRUGGLE WITH THE NEXT COLD FRONTAL BOUNDARY
FORECAST TO REACH THE FLORIDA PANHANDLE ON MONDAY. BEFORE THAT...WE
SHOULD BE IN A RELATIVELY BENIGN ENVIRONMENT ALTHOUGH SUFFICIENT
MOISTURE WILL EXIST FOR A SLIGHT CHANCE OF SHOWERS BOTH SUNDAY AND
MONDAY.
THERE IS LITTLE DOUBT THAT THE COLD FRONT WILL BE RUNNING OUT OF
STEAM AS IT MOVES INTO FLORIDA. THE BOUNDARY WILL ALREADY HAVE
BECOME PARALLEL WITH THE MID-LEVEL FLOW MONDAY NIGHT AS A TROUGH
DEEPENS OUT WEST ALLOWING HEIGHTS TO RISE OVER THE EAST ON TUESDAY.
THE GFS PUSHES THE FRONT SOUTH OF THE AREA BY TUESDAY EVENING WHILE
THE ECMWF HOLDS UP ACROSS THE TAMPA BAY AREA. THE CANADIAN MODEL
SHOWS THE FRONT ALREADY STATIONARY ACROSS NORTH FLORIDA TUESDAY
EVENING. ONE THING TO NOTE IS THAT THE CURRENT 00Z GFS IS NEARLY
IDENTICAL IN TIMING TO THE 12Z ECMWF. THIS IS ALSO VERY CLOSE TO
WHERE THE PREVIOUS FORECAST WAS. WITH THIS IN MIND...BLENDED THE 12Z
ECMWF AND 00Z GFS WHICH ALLOWS THE FRONT TO COME THROUGH THE REGION
ON TUESDAY...BUT WOULD NOT BE SURPRISED IF WE NEED TO BACK THE FRONT
UP A BIT FOR THE NEXT FORECAST CYCLE.
AS MENTIONED YESTERDAY...MODELS THEN SIGNAL A POTENTIAL OVER-RUNNING
EVENT WHICH WILL BRING MORE CLOUDS AND CONTINUED RAIN CHANCES EVEN
AFTER THE FRONT GOES BY.
&&
.AVIATION...
PATCHY MORNING FOG COULD BRING BRIEF PERIODS OF MVFR PERHAPS IFR
CONDITIONS TO PGD. OTHERWISE LOOK FOR A FEW SHOWERS TODAY BUT
COVERAGE TOO LOW FOR MORE THAN VCSH. BETTER INSTABILITY OVER SOUTH
FLORIDA WARRANTS VCTS FOR FMY AND RSW.
&&
.MARINE...
EASTERLY FLOW BELOW HEADLINE CRITERIA WILL CONTINUE ACROSS THE
MARINE ZONES OF THE EASTERN GULF OF MEXICO THROUGH FRIDAY MORNING.
THE LOCAL GRADIENT IS EXPECTED TO THEN WEAKEN FURTHER BY LATER
FRIDAY AND INTO THE UPCOMING WEEKEND. THIS WEAK GRADIENT WILL KEEP
WINDS AND SEAS LOW. WINDS WILL THEN INCREASE OUT OF THE SOUTH EARLY
NEXT WEEK AHEAD OF AN APPROACHING COLD FRONT.
&&
.FIRE WEATHER...
RELATIVE HUMIDITY WILL REMAIN WELL ABOVE CRITICAL LEVELS THROUGH THE
UPCOMING WEEKEND. MAIN FIRE WEATHER CONCERN WILL BE LOWER DISPERSION
INDICES THE NEXT COUPLE OF DAYS. THE LOWER LDSI VALUES WILL BE THE
RESULT IN LESS MIXING TODAY AND THEN A WEAKENING OF THE OVERALL WIND
FIELDS DURING FRIDAY AND SATURDAY. OTHERWISE NO SIGNIFICANT FIRE
WEATHER CONCERNS ARE ANTICIPATED.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 77 61 79 63 / 30 10 10 0
FMY 79 61 81 64 / 40 10 20 10
GIF 77 56 81 62 / 40 10 20 10
SRQ 76 58 78 61 / 30 10 10 0
BKV 77 54 80 56 / 30 10 10 0
SPG 75 63 78 64 / 30 10 10 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS DES MOINES IA
315 PM CST THU DEC 6 2012
.SHORT TERM /TONIGHT/...
WEAK SHORTWAVE WILL CONTINUE TO PUSH EAST OF THE FORECAST AREA LATE
THIS AFTERNOON INTO THE EARLY EVENING WHILE A SECOND SHORTWAVE WILL
MOVE ACROSS SOUTHERN IOWA/NORTHERN MISSOURI THROUGH 09Z FRIDAY.
WEAK BOUNDARY ASSOCIATED WITH THE FIRST SHORTWAVE LOOKS TO BE INTO
NORTHERN MISSOURI AND FAR SOUTHEAST IOWA BY 00Z FRIDAY. SLIGHTLY
BETTER FORCING WITH THE SECOND VORT MAX LOOKS TO BE CONFINED TO
SOUTHEAST IOWA. THIS IS EVIDENT ALONG THE 295K TO 305K ISENTROPIC
SURFACE WHICH COINCIDES TO THE WEAK THETA-E ADVECTION AOA 700MB.
BUFR SOUNDINGS SATURATED ABOVE 700MB SO PRECIP WILL BE HIGH BASED
THIS EVENING. THE HI-RES MODELS RUNS OF THE NMM/ARW WRF AND HRRR ARE
IN GOOD AGREEMENT WITH SOME LIGHT PRECIP OVER THE SOUTH THROUGH 09Z
FRIDAY AND INCREASED POPS TO LIKELIES THROUGH 06Z IN THIS AREA.
THE WRF SIMULATED GOES-R PRODUCTS ARE DEPICTING A CLEAR SLOT MOVING
INTO CENTRAL IOWA FROM WEST TO EAST LATE TONIGHT INTO THE OVERNIGHT
HOURS AND SOMEWHAT AGREE THERE SHOULD BE A BRIEF PERIOD OF CLEAR
SKIES B/T 03-09Z. HOWEVER...THE SIMULATED PRODUCTS DO NOT HAVE A
GOOD HANDLE ON CURRENT SATELLITE TRENDS WRT TO HIGHER CLOUDS IN
NORTHWEST IOWA. SO DID NOT GO COMPLETELY CLEAR IN THE NORTH WITH
ANOTHER WAVE MOVING INTO NORTHERN IOWA FRIDAY. LEANED TOWARD THE
COOLER NAM12 FOR LOWS TONIGHT IN NORTHERN IOWA AND THE NISH
VALLEY...THEN CLOSER TO THE GFS ACROSS THE SOUTHEAST.
.LONG TERM /FRIDAY THROUGH THURSDAY/...
MORE WRINKLES FOR THE WEEKEND EVENT...THOUGH SOME CONSENSUS
BEGINNING TO SHOW UP REGARDING PREFERRED SOLUTION AND FORECAST.
FIRST OF ALL THE SYSTEM ON FRIDAY APPEARS TO BE GRAZING THE FAR
NORTH WITH SOME LIGHT SNOW AS MORE OF THE FORCING IN THE PAST TWO
RUNS WILL OCCUR OVER SOUTHERN MINNESOTA...WITH JUST SOME LIGHT
PRECIPITATION REACHING THE FAR NORTHERN COUNTIES OF THE FORECAST
AREA AS THE SYSTEM PASSES TO THE EAST. THIS WILL LIMIT ANY SNOWFALL
ACCUMULATIONS TO AN INCH OR LESS WITH THE FIRST WAVE DROPPING EAST
SOUTHEAST WITH TIME TOMORROW. ONE OF THE WRINKLES IN THE UPCOMING
FORECAST HAS BEEN A SHIFT TO LESS COLD AIR ARRIVING IN THE NEXT 48
HOURS AHEAD OF THE LATE WEEKEND WAVES. THIS WILL MODERATE BOTH
HIGHS AND LOWS...RESULTING IN A SLIGHTLY LONGER CHANGEOVER FROM
LIQUID TO FROZEN PRECIPITATION ON SUNDAY. THIS IS MAINLY DUE TO THE
LACK OF UPPER LEVEL ENERGY PHASING WHICH KEEPS THE NORTHERN STREAM
SHORT WAVE STRONGER AND THE COLD AIR FROM DRIVING SOUTH BEHIND THE
SYSTEM FAST ENOUGH TO INTERACT WITH THE SOUTHERN STREAM. THUS...WITH
LITTLE COLD AIR ADVECTION IN THE OFFING UNTIL THE STORM PASSES TO
THE EAST SUNDAY EVENING...THERE WILL BE LITTLE AMPLIFICATION OF THE
ENTIRE SYSTEM AND LESSER AMOUNTS OF FORCING...QPF...AND SNOWFALL
PRODUCTION OVER THE FORECAST AREA. NEVER THE LESS...SOME
ACCUMULATION IS EXPECTED AS THE TIMING OVER THE NORTH FAVORS A
QUICKER CHANGEOVER COMPARED TO THE SOUTH. WITH CONTINUED UNCERTAINTY
IN BOTH TIMING AND AREAL COVERAGE OF PRECIPITATION OVER THE RANGE OF
MODEL SOLUTIONS... HAVE OPTED TO LEAN TOWARD A MANUAL BLEND OF THE
EURO/NAM/GEM WITH LESS EMPHASIS ON THE GFS WHICH HAS DONE A COMPLETE
REVERSAL SINCE YESTERDAY. THE ONLY TREND IN THE MODELS NOW IS LITTLE
TO NO PHASING OF THE NORTHERN AND SOUTHERN STREAMS AND SLIGHTLY
WARMER TEMPS AS PREVIOUSLY MENTIONED. THUS...SOME LIGHT SNOW WITH A
POTENTIAL FOR A BRIEF PERIOD OF HEAVIER RAIN OR SNOW SATURDAY NIGHT
LATE NORTHEAST IS EXPECTED AS THE SYSTEM ROLLS ON THROUGH. SUNDAY
FOR THE MOST PART WILL EXPERIENCE FALLING TEMPERATURES WITH LESS
INTENSE PRECIPITATION. LIGHT ACCUMULATIONS OF SNOW WILL OCCUR BOTH
SATURDAY NIGHT AND SUNDAY OVER THE FORECAST AREA AND AMOUNTS WILL
RANGE FROM NEAR ONE HALF INCH IN THE SOUTH TO NEARLY 1.5 TO 2 INCHES
IN THE NORTHEAST. THOUGH THE COLD AIR FINALLY ARRIVES BY SUNDAY
NIGHT AND MONDAY...SOME MODERATION IS ALREADY EXPECTED TO OCCUR BY
TUESDAY THROUGH THURSDAY WHEN HIGHS REACH THE 30S TO LOWER 40S OVER
THE REGION SO WHAT SNOW DOES FALL THIS WEEKEND WILL SLOWLY DISAPPEAR
TOWARD NEXT THURSDAY. LITTLE TO NO PRECIPITATION WILL OCCUR AFTER
THE STORM SUNDAY...SO THE BALANCE OF THE EXTENDED FORECAST LOOKS
DRY.
&&
.AVIATION...06/18Z
WEAK BOUNDARY WILL CONTINUE TO MOVE SOUTHEAST THIS AFTERNOON AND
BRING A FEW SCATTERED LIGHT SHOWERS WITH IT. HOWEVER...CONDITIONS
WILL REMAIN VFR THROUGH THE ENTIRE TAF PERIOD. ONLY CONCERN IS WIND
SHIFT TO THE NORTHWEST WITH THE COLD FRONT THIS AFTERNOON AND THEN
MORE TOWARDS THE NORTHEAST OVERNIGHT AS SURFACE HIGH PRESSURE MOVES
INTO THE STATE.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/AVIATION...PODRAZIK
LONG TERM...REV
AREA FORECAST DISCUSSION
NWS GOODLAND KS
446 PM MST FRI DEC 7 2012
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 144 PM MST FRI DEC 7 2012
LATEST SATELLITE IMAGERY DEPICTS AN UPPER LEVEL TROUGH AXIS
EXTENDING FROM SOUTHEASTERN COLORADO NORTHEAST INTO NORTHERN MINNESOTA.
BEHIND THE TROUGH AXIS RUC ANALYSIS PLACES A SHORT WAVE TROUGH OVER
THE NE/SD LINE. AT THE SURFACE A PRE-FRONTAL TROUGH WAS MOVING
SOUTHEAST THROUGH THE PLAINS. SUBSIDENCE BEHIND THE SHORT WAVE TROUGH
AND TROUGH AXIS HAS LEAD TO CLEARING SKIES BEHIND THE SURFACE
FEATURE.
LATE THIS EVENING A WEAK SHORT WAVE TROUGH WILL DEVELOP OVER EASTERN
COLORADO AND PROGRESS ACROSS THE WESTERN HALF OF THE TRI-STATE
AREA. SREF/NAM ISENTROPIC ANALYSIS INDICATES LIFT AHEAD OF THE
SHORT WAVE TROUGH AROUND 700MB WHERE POINT SOUNDINGS ALSO SATURATE.
THE DRAWBACK IS A DRY LAYER BELOW THIS WHICH WILL LIMIT HOW MUCH
SNOW WILL REACH THE GROUND. THE MCCOOK AND NORTON AREA HAD A
SIMILAR SETUP THIS MORNING...WITH THE MCCOOK AIRPORT REPORTING
DRIZZLE. WITH THIS IN MIND WILL PLACE A MENTION OF FLURRIES AHEAD
OF THE SHORT WAVE TROUGH. THE FLURRIES WILL GENERALLY MOVE FROM
SOUTHWEST TO NORTHEAST DURING THE NIGHT OVER THE WESTERN HALF OF THE
AREA.
SATURDAY THE SHORT WAVE TROUGH WILL CONTINUE TO MOVE ACROSS THE AREA
DURING THE MORNING. HAVE THE FLURRIES CHANGING TO DRIZZLE
DURING THE LATE MORNING AS SURFACE TEMPERATURES WARM INTO THE LOWER
30S. THE ISENTROPIC LIFT AHEAD OF THE TROUGH WILL EXIT THE AREA BY
EARLY AFTERNOON. SOUTH WINDS WILL BE BREEZY DURING THE AFTERNOON AS
25KT 850MB WINDS MIX TO THE GROUND AND THE SURFACE PRESSURE GRADIENT
TIGHTENS. THE BREEZY WINDS WILL HELP WARM TEMPERATURES AHEAD OF THE
NEXT COLD FRONT...WHICH WILL MOVE INTO THE AREA DURING THE MID TO
LATE AFTERNOON. LIFTING AND MOISTURE WILL BE BEST ALONG AND SHORTLY
BEHIND THE FRONT. HOWEVER MODELS SHOW A FAIRLY DEEP DRY LAYER AS
THE FRONT MOVES THROUGH...WHICH MAY LIMIT THE AMOUNT OF RAIN THAT
REACHES THE GROUND. MODELS SHOW RAPID PRESSURE RISE BEHIND THE COLD
FRONT...WHICH WILL CAUSE WINDS TO STRENGTHEN BEHIND THE FRONT.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 247 PM MST
FRI DEC 7 2012
THE COLD FRONT WILL CONTINUE TO PUSH ACROSS THE FORECAST AREA
SATURDAY NIGHT. THE FAVORED AREA OF PRECIPITATION WILL INITIALLY BE
ACROSS THE NORTHERN SECTIONS OF THE FORECAST AREA IN THE VICINITY
OF THE FRONT WITH LIGHT RAIN CHANGING QUICKLY OVER TO LIGHT SNOW
AROUND SUNSET. A SLIGHT CHANCE OF LIGHT SNOW WILL SPREAD ACROSS THE
FORECAST AREA WITH THE FRONT...WITH THE BEST CHANCE OF
PRECIPITATION REMAINING ALONG THE NORTHERN TIER OF COUNTIES WHERE
THE SYNOPTIC SCALE LIFT REMAINS GREATER AS A SERIES OF SHORT WAVES
SHEAR OUT ACROSS THE PLAINS AHEAD OF THE MAIN UPPER TROUGH. THE
POSSIBILITY OF PRECIPITATION DECREASES THROUGH THE REMAINDER OF
SATURDAY NIGHT AND SUNDAY MORNING...WITH LIGHT SNOW ENDING BY MID
DAY ON SUNDAY. WITH THE STEEP PRESSURE GRADIENT REMAINING OVER THE
CENTRAL HIGH PLAINS REGION...EXPECT NORTH WINDS OF 20-30 MPH WILL
BE COMMON DURING THE DAY ON SUNDAY.
THE PRIMARY DEEP UPPER TROUGH SWEEPS QUICKLY THROUGH THE REGION
SUNDAY NIGHT WITH A COLD AREA OF HIGH PRESSURE MOVING IN BEHIND
THE FRONT. OVERNIGHT LOW TEMPERATURES WILL DROP INTO THE SINGLE
DIGITS AS SKIES ALSO BEGIN TO CLEAR OUT AND WINDS SLACKEN SUNDAY
NIGHT.
A SERIES OF OPEN WAVES WILL MOVE THROUGH THE UPPER FLOW NEXT
WEEK. ALTHOUGH THE PATTERN REMAINS ACTIVE...NO ADDITIONAL
PRECIPITATION IS EXPECTED THROUGH NEXT WEEK. COLDER TEMPERATURES
WILL CONTINUE INTO THE BEGINNING OF NEXT WEEK WITH A GRADUAL
WARMING BRINGING TEMPERATURES BACK TO NEAR AVERAGE FOR THIS TIME
OF YEAR THROUGH THE MIDDLE AND END OF NEXT WEEK.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 441 PM MST FRI DEC 7 2012
DESPITE STAYING IN THE VFR CATEGORY THROUGH THE WHOLE
PERIOD...THERE WILL BE VARIABLE AND CHANGING CONDITIONS DURING THE
WHOLE TIME. VARIABLE LOW TO MID LEVEL CLOUD COVER WILL BE IN
PLACE. THERE IS A POSSIBILITY...ESPECIALLY AT KMCK...THE FLURRIES
COULD OCCUR TONIGHT AND DRIZZLE TOMORROW. HOWEVER...THE SPOTTY AND
UNCERTAIN NATURE OF THIS IS TOO LOW TO PUT IN EITHER TAF AT THIS
TIME. EVEN IF SOMETHING WOULD HAPPEN TO OCCUR AT EITHER SITE DO
NOT EXPECT ANY SIGNIFICANT REDUCTIONS IN VISIBILITY.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JTL
LONG TERM...LOCKHART
AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
1233 PM CST THU DEC 6 2012
.UPDATE...
CLOUDS CONTINUE TO DECREASE FROM THE COAST INLAND ACRS LOWER SE TX
AND SW LA. ADJUSTED SKY GRIDS ACCORDINGLY AND ALSO BUMPED UP AFTN
HIGHS IN THIS AREA WITH ONLY MINOR TWEAKS ELSEWHERE. ADJUSTED
HOURLY TEMPS/DEWPOINTS TO REFLECT THESE CHANGES ALONG WITH RECENT
OBSERVATIONS. UPDATED PRODUCTS OUT SHORTLY. 24
&&
.PREV DISCUSSION... /ISSUED 1141 AM CST THU DEC 6 2012/
AVIATION...
STLT IS INDICATING CLDS LIFTING ALONG THE COAST AND THIS
PATTERN WILL SPREAD INLAND AT LEAST OVER THE NEXT SEVERAL
HOURS BEFORE CLOUDS START TO REDEVELOP DURING THE EVENING
HOURS WITH FOG DEVELOPING TOWARDS MIDNIGHT.
PREV DISCUSSION... /ISSUED 1115 AM CST THU DEC 6 2012/
UPDATE...
LOW CLOUDS HANGING ON ACRS LA AND E TX THIS MORNING AS MOISTURE
REMAINS TRAPPED BELOW DRIER AIR ALOFT. KLCH AND KSHV 12Z SOUNDINGS
SHOWS THIS MOISTURE CONFINED MAINLY BELOW 900 TO 850 MB. RECENT
SATELLITE TRENDS SHOW SOME CLEARING NR THE COAST AS WELL AS A FEW
BREAKS OVER SE TX AND S CNTL LA. FCST SOUNDINGS SHOW CLOUDS
LINGERING THROUGHOUT MUCH OF THE DAY...BUT A FEW LOCATIONS COULD
BECOME PARTLY CLOUDY DURING THE AFTN GIVEN THE AFOREMENTIONED
SATELLITE TRENDS AND POTENTIAL FOR DRIER AIR MIXING DOWN HELPING
TO ERODE THE CLOUD LAYER. WENT A LITTLE MORE PESSIMISTIC WITH THIS
MORNINGS UPDATE...KEEPING CLOUDS HANGING ON ACRS MUCH OF THE AREA
UNTIL LATE THIS AFTN. THIS IN TURN HAS ALSO AFFECTED TEMPERATURES
TODAY...WITH 11 AM TEMPS STILL IN THE UPPER 50S TO LOWER 60S ACRS
THE AREA. WENT AHEAD AND LOWERED MAX TEMPS A FEW DEGREES...AND
THINK UNLESS AREAS BEGIN TO SEE SOME SUN SOON...MAX TEMPS WILL
REMAIN BELOW 70. WILL CONTINUE TO MONITOR TRENDS THROUGH EARLY
AFTN AND UPDATE IF NEEDED. 24
PREV DISCUSSION... /ISSUED 558 AM CST THU DEC 6 2012/
AVIATION...RUC WAS USED DUE TO INHERITED HOLES IN THE LOW CLOUD
DECK AND NEEDED CLOSER SPACIAL AND TEMPORAL COVERAGE. HOLE CLOSED
IN AT LCH AFTER MIDNIGHT. IFR CONDITIONS ABOUND WITH SOME LIFR
OVER THE EASTERN TERMINALS AEX, ARA, AND LFT. RUC AND NAM ARE
RATHER SLOW ON IMPROVEMENT. WHERE PREVIOUS HOLE EXISTED AROUND
LCH, CHOSE TO IMPROVE TO VFR BY MID-DAY. SINCE RADIATION WILL GET
A BETTER FOOTHOLD TNITE, BROUGHT CONDITIONS DOWN HARD TO VLIFR
AFTER MIDNIGHT IN DENSE FOG AT FOR LCH.
ARA WITH LIFR SHOULD GRADUALLY IMPROVE TO MVFR THIS AFTERNOON ONLY
TO CRUMP DOWN TO VLIFR IN DENSE FOG SHORTLY BEYOND MIDNIGHT. LIFR
SHOULD RULE THE REMAINING TERMINALS LATE TNITE, THAT BEING LFT,
AEX, AND BPT. THIS IS A VERY PERSISTENT PATTERN WITH TRAPPED
MOISTURE IN THE LOW LEVELS UNDER AN INVERSION.
SWEENEY
PREV DISCUSSION... /ISSUED 418 AM CST THU DEC 6 2012/
SYNOPSIS...
AN ATLANTIC DOME OF HIGH PRESSURE WILL BUILD WESTWARD THROUGH
GEORGIA...WASHING OUT THE SHALLOW LOW LOCATED JUST OFFSHORE HOUMA
BY FRIDAY.
FURTHER WEST...A LEESIDE LOW IS FORMING ACROSS THE TEXAS PANHANDLE.
DISCUSSION...
FOR THIS MORNING...DRY MEXICAN AIR IS RIDING IN ON A LOW-LEVEL
SOUTHWESTERLY AIR STREAM ACROSS SOUTHEAST TEXAS. THE OVERRIDING
DRY AIR IS TRAPPING MOISTURE NEAR THE SURFACE. PATCHY DENSE FOG IS
POSSIBLE NEAR DAWN.
OTHERWISE...SKIES WILL BECOME PARTLY CLOUDY...FROM WEST TO EAST.
THE AFTERNOON TEMPERATURES WILL BE RUNNING FROM 5 DEGREES ABOVE
NORMAL AT THE COAST...TO AROUND 10 DEGREES ACROSS THE PINEY HILLS.
FOR TONIGHT...FOG WILL BE RETURNING. OTHERWISE...THE OVERNIGHT
MINIMUMS WILL BE RUNNING FROM 10 TO 15 DEGREES ABOVE NORMAL.
OUTLOOK...
A STRONG CANADIAN FRONT WILL TRAVEL THROUGH THE FORECAST AREA
DURING THE OVERNIGHT HOURS ON SUNDAY.
NUMEROUS SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THIS SYSTEM.
THE FORECAST ENVIRONMENT WITHIN THE WARM SECTOR WEDGE (AS
DEPICTED BY THE GFS MODEL IS AS FOLLOWS)...
SIGNIFICANT LIFT...MESO-SYNOPTIC LIFT (ASSOCIATED THE ENTRANCE
REGION OF A SOUTHWESTERLY JET STREAK) WILL PHASE IN WITH THE
FRONTAL LIFT.
ADEQUATE MOISTURE...PRECIPITABLE WATER WILL BE NEAR 1.5 INCHES.
THE 1000-500 MB MEAN RELATIVE HUMIDITY WILL BE NEAR 80 PERCENT.
MARGINAL INSTABILITY AND MARGINAL SHEAR...CURRENTLY THE LIMITING
FACTOR FOR LONG-LIVED ORGANIZED THUNDERSTORMS.
21
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 68 54 73 58 / 10 10 10 10
KBPT 72 55 74 61 / 10 10 10 10
KAEX 66 53 72 57 / 10 10 10 10
KLFT 69 56 74 58 / 10 10 10 10
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
TX...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
1141 AM CST THU DEC 6 2012
.AVIATION...
STLT IS INDICATING CLDS LIFTING ALONG THE COAST AND THIS
PATTERN WILL SPREAD INLAND AT LEAST OVER THE NEXT SEVERAL
HOURS BEFORE CLOUDS START TO REDEVELOP DURING THE EVENING
HOURS WITH FOG DEVELOPING TOWARDS MIDNIGHT.
&&
.PREV DISCUSSION... /ISSUED 1115 AM CST THU DEC 6 2012/
UPDATE...
LOW CLOUDS HANGING ON ACRS LA AND E TX THIS MORNING AS MOISTURE
REMAINS TRAPPED BELOW DRIER AIR ALOFT. KLCH AND KSHV 12Z SOUNDINGS
SHOWS THIS MOISTURE CONFINED MAINLY BELOW 900 TO 850 MB. RECENT
SATELLITE TRENDS SHOW SOME CLEARING NR THE COAST AS WELL AS A FEW
BREAKS OVER SE TX AND S CNTL LA. FCST SOUNDINGS SHOW CLOUDS
LINGERING THROUGHOUT MUCH OF THE DAY...BUT A FEW LOCATIONS COULD
BECOME PARTLY CLOUDY DURING THE AFTN GIVEN THE AFOREMENTIONED
SATELLITE TRENDS AND POTENTIAL FOR DRIER AIR MIXING DOWN HELPING
TO ERODE THE CLOUD LAYER. WENT A LITTLE MORE PESSIMISTIC WITH THIS
MORNINGS UPDATE...KEEPING CLOUDS HANGING ON ACRS MUCH OF THE AREA
UNTIL LATE THIS AFTN. THIS IN TURN HAS ALSO AFFECTED TEMPERATURES
TODAY...WITH 11 AM TEMPS STILL IN THE UPPER 50S TO LOWER 60S ACRS
THE AREA. WENT AHEAD AND LOWERED MAX TEMPS A FEW DEGREES...AND
THINK UNLESS AREAS BEGIN TO SEE SOME SUN SOON...MAX TEMPS WILL
REMAIN BELOW 70. WILL CONTINUE TO MONITOR TRENDS THROUGH EARLY
AFTN AND UPDATE IF NEEDED. 24
PREV DISCUSSION... /ISSUED 558 AM CST THU DEC 6 2012/
AVIATION...RUC WAS USED DUE TO INHERITED HOLES IN THE LOW CLOUD
DECK AND NEEDED CLOSER SPACIAL AND TEMPORAL COVERAGE. HOLE CLOSED
IN AT LCH AFTER MIDNIGHT. IFR CONDITIONS ABOUND WITH SOME LIFR
OVER THE EASTERN TERMINALS AEX, ARA, AND LFT. RUC AND NAM ARE
RATHER SLOW ON IMPROVEMENT. WHERE PREVIOUS HOLE EXISTED AROUND
LCH, CHOSE TO IMPROVE TO VFR BY MID-DAY. SINCE RADIATION WILL GET
A BETTER FOOTHOLD TNITE, BROUGHT CONDITIONS DOWN HARD TO VLIFR
AFTER MIDNIGHT IN DENSE FOG AT FOR LCH.
ARA WITH LIFR SHOULD GRADUALLY IMPROVE TO MVFR THIS AFTERNOON ONLY
TO CRUMP DOWN TO VLIFR IN DENSE FOG SHORTLY BEYOND MIDNIGHT. LIFR
SHOULD RULE THE REMAINING TERMINALS LATE TNITE, THAT BEING LFT,
AEX, AND BPT. THIS IS A VERY PERSISTENT PATTERN WITH TRAPPED
MOISTURE IN THE LOW LEVELS UNDER AN INVERSION.
SWEENEY
PREV DISCUSSION... /ISSUED 418 AM CST THU DEC 6 2012/
SYNOPSIS...
AN ATLANTIC DOME OF HIGH PRESSURE WILL BUILD WESTWARD THROUGH
GEORGIA...WASHING OUT THE SHALLOW LOW LOCATED JUST OFFSHORE HOUMA
BY FRIDAY.
FURTHER WEST...A LEESIDE LOW IS FORMING ACROSS THE TEXAS PANHANDLE.
DISCUSSION...
FOR THIS MORNING...DRY MEXICAN AIR IS RIDING IN ON A LOW-LEVEL
SOUTHWESTERLY AIR STREAM ACROSS SOUTHEAST TEXAS. THE OVERRIDING
DRY AIR IS TRAPPING MOISTURE NEAR THE SURFACE. PATCHY DENSE FOG IS
POSSIBLE NEAR DAWN.
OTHERWISE...SKIES WILL BECOME PARTLY CLOUDY...FROM WEST TO EAST.
THE AFTERNOON TEMPERATURES WILL BE RUNNING FROM 5 DEGREES ABOVE
NORMAL AT THE COAST...TO AROUND 10 DEGREES ACROSS THE PINEY HILLS.
FOR TONIGHT...FOG WILL BE RETURNING. OTHERWISE...THE OVERNIGHT
MINIMUMS WILL BE RUNNING FROM 10 TO 15 DEGREES ABOVE NORMAL.
OUTLOOK...
A STRONG CANADIAN FRONT WILL TRAVEL THROUGH THE FORECAST AREA
DURING THE OVERNIGHT HOURS ON SUNDAY.
NUMEROUS SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THIS SYSTEM.
THE FORECAST ENVIRONMENT WITHIN THE WARM SECTOR WEDGE (AS
DEPICTED BY THE GFS MODEL IS AS FOLLOWS)...
SIGNIFICANT LIFT...MESO-SYNOPTIC LIFT (ASSOCIATED THE ENTRANCE
REGION OF A SOUTHWESTERLY JET STREAK) WILL PHASE IN WITH THE
FRONTAL LIFT.
ADEQUATE MOISTURE...PRECIPITABLE WATER WILL BE NEAR 1.5 INCHES.
THE 1000-500 MB MEAN RELATIVE HUMIDITY WILL BE NEAR 80 PERCENT.
MARGINAL INSTABILITY AND MARGINAL SHEAR...CURRENTLY THE LIMITING
FACTOR FOR LONG-LIVED ORGANIZED THUNDERSTORMS.
21
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 54 74 59 77 61 / 10 10 10 20 10
KBPT 55 74 61 76 63 / 10 10 10 20 10
KAEX 53 73 57 77 59 / 10 10 10 20 10
KLFT 56 74 58 76 60 / 10 10 10 20 10
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
TX...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
1115 AM CST THU DEC 6 2012
.UPDATE...
LOW CLOUDS HANGING ON ACRS LA AND E TX THIS MORNING AS MOISTURE
REMAINS TRAPPED BELOW DRIER AIR ALOFT. KLCH AND KSHV 12Z SOUNDINGS
SHOWS THIS MOISTURE CONFINED MAINLY BELOW 900 TO 850 MB. RECENT
SATELLITE TRENDS SHOW SOME CLEARING NR THE COAST AS WELL AS A FEW
BREAKS OVER SE TX AND S CNTL LA. FCST SOUNDINGS SHOW CLOUDS
LINGERING THROUGHOUT MUCH OF THE DAY...BUT A FEW LOCATIONS COULD
BECOME PARTLY CLOUDY DURING THE AFTN GIVEN THE AFOREMENTIONED
SATELLITE TRENDS AND POTENTIAL FOR DRIER AIR MIXING DOWN HELPING
TO ERODE THE CLOUD LAYER. WENT A LITTLE MORE PESSIMISTIC WITH THIS
MORNINGS UPDATE...KEEPING CLOUDS HANGING ON ACRS MUCH OF THE AREA
UNTIL LATE THIS AFTN. THIS IN TURN HAS ALSO AFFECTED TEMPERATURES
TODAY...WITH 11 AM TEMPS STILL IN THE UPPER 50S TO LOWER 60S ACRS
THE AREA. WENT AHEAD AND LOWERED MAX TEMPS A FEW DEGREES...AND
THINK UNLESS AREAS BEGIN TO SEE SOME SUN SOON...MAX TEMPS WILL
REMAIN BELOW 70. WILL CONTINUE TO MONITOR TRENDS THROUGH EARLY
AFTN AND UPDATE IF NEEDED. 24
&&
.PREV DISCUSSION... /ISSUED 558 AM CST THU DEC 6 2012/
AVIATION...RUC WAS USED DUE TO INHERITED HOLES IN THE LOW CLOUD
DECK AND NEEDED CLOSER SPACIAL AND TEMPORAL COVERAGE. HOLE CLOSED
IN AT LCH AFTER MIDNIGHT. IFR CONDITIONS ABOUND WITH SOME LIFR
OVER THE EASTERN TERMINALS AEX, ARA, AND LFT. RUC AND NAM ARE
RATHER SLOW ON IMPROVEMENT. WHERE PREVIOUS HOLE EXISTED AROUND
LCH, CHOSE TO IMPROVE TO VFR BY MID-DAY. SINCE RADIATION WILL GET
A BETTER FOOTHOLD TNITE, BROUGHT CONDITIONS DOWN HARD TO VLIFR
AFTER MIDNIGHT IN DENSE FOG AT FOR LCH.
ARA WITH LIFR SHOULD GRADUALLY IMPROVE TO MVFR THIS AFTERNOON ONLY
TO CRUMP DOWN TO VLIFR IN DENSE FOG SHORTLY BEYOND MIDNIGHT. LIFR
SHOULD RULE THE REMAINING TERMINALS LATE TNITE, THAT BEING LFT,
AEX, AND BPT. THIS IS A VERY PERSISTENT PATTERN WITH TRAPPED
MOISTURE IN THE LOW LEVELS UNDER AN INVERSION.
SWEENEY
PREV DISCUSSION... /ISSUED 418 AM CST THU DEC 6 2012/
SYNOPSIS...
AN ATLANTIC DOME OF HIGH PRESSURE WILL BUILD WESTWARD THROUGH
GEORGIA...WASHING OUT THE SHALLOW LOW LOCATED JUST OFFSHORE HOUMA
BY FRIDAY.
FURTHER WEST...A LEESIDE LOW IS FORMING ACROSS THE TEXAS PANHANDLE.
DISCUSSION...
FOR THIS MORNING...DRY MEXICAN AIR IS RIDING IN ON A LOW-LEVEL
SOUTHWESTERLY AIR STREAM ACROSS SOUTHEAST TEXAS. THE OVERRIDING
DRY AIR IS TRAPPING MOISTURE NEAR THE SURFACE. PATCHY DENSE FOG IS
POSSIBLE NEAR DAWN.
OTHERWISE...SKIES WILL BECOME PARTLY CLOUDY...FROM WEST TO EAST.
THE AFTERNOON TEMPERATURES WILL BE RUNNING FROM 5 DEGREES ABOVE
NORMAL AT THE COAST...TO AROUND 10 DEGREES ACROSS THE PINEY HILLS.
FOR TONIGHT...FOG WILL BE RETURNING. OTHERWISE...THE OVERNIGHT
MINIMUMS WILL BE RUNNING FROM 10 TO 15 DEGREES ABOVE NORMAL.
OUTLOOK...
A STRONG CANADIAN FRONT WILL TRAVEL THROUGH THE FORECAST AREA
DURING THE OVERNIGHT HOURS ON SUNDAY.
NUMEROUS SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THIS SYSTEM.
THE FORECAST ENVIRONMENT WITHIN THE WARM SECTOR WEDGE (AS
DEPICTED BY THE GFS MODEL IS AS FOLLOWS)...
SIGNIFICANT LIFT...MESO-SYNOPTIC LIFT (ASSOCIATED THE ENTRANCE
REGION OF A SOUTHWESTERLY JET STREAK) WILL PHASE IN WITH THE
FRONTAL LIFT.
ADEQUATE MOISTURE...PRECIPITABLE WATER WILL BE NEAR 1.5 INCHES.
THE 1000-500 MB MEAN RELATIVE HUMIDITY WILL BE NEAR 80 PERCENT.
MARGINAL INSTABILITY AND MARGINAL SHEAR...CURRENTLY THE LIMITING
FACTOR FOR LONG-LIVED ORGANIZED THUNDERSTORMS.
21
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 65 54 73 58 / 10 10 10 10
KBPT 65 55 74 61 / 10 10 10 10
KAEX 64 53 73 57 / 10 10 10 10
KLFT 65 56 74 58 / 10 10 10 10
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
TX...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
558 AM CST THU DEC 6 2012
.AVIATION...RUC WAS USED DUE TO INHERITED HOLES IN THE LOW CLOUD
DECK AND NEEDED CLOSER SPACIAL AND TEMPORAL COVERAGE. HOLE CLOSED
IN AT LCH AFTER MIDNIGHT. IFR CONDITIONS ABOUND WITH SOME LIFR
OVER THE EASTERN TERMINALS AEX, ARA, AND LFT. RUC AND NAM ARE
RATHER SLOW ON IMPROVEMENT. WHERE PREVIOUS HOLE EXISTED AROUND
LCH, CHOSE TO IMPROVE TO VFR BY MID-DAY. SINCE RADIATION WILL GET
A BETTER FOOTHOLD TNITE, BROUGHT CONDITIONS DOWN HARD TO VLIFR
AFTER MIDNIGHT IN DENSE FOG AT FOR LCH.
ARA WITH LIFR SHOULD GRADUALLY IMPROVE TO MVFR THIS AFTERNOON ONLY
TO CRUMP DOWN TO VLIFR IN DENSE FOG SHORTLY BEYOND MIDNIGHT. LIFR
SHOULD RULE THE REMAINING TERMINALS LATE TNITE, THAT BEING LFT,
AEX, AND BPT. THIS IS A VERY PERSISTENT PATTERN WITH TRAPPED
MOISTURE IN THE LOW LEVELS UNDER AN INVERSION.
SWEENEY
&&
.PREV DISCUSSION... /ISSUED 418 AM CST THU DEC 6 2012/
SYNOPSIS...
AN ATLANTIC DOME OF HIGH PRESSURE WILL BUILD WESTWARD THROUGH
GEORGIA...WASHING OUT THE SHALLOW LOW LOCATED JUST OFFSHORE HOUMA
BY FRIDAY.
FURTHER WEST...A LEESIDE LOW IS FORMING ACROSS THE TEXAS PANHANDLE.
DISCUSSION...
FOR THIS MORNING...DRY MEXICAN AIR IS RIDING IN ON A LOW-LEVEL
SOUTHWESTERLY AIR STREAM ACROSS SOUTHEAST TEXAS. THE OVERRIDING
DRY AIR IS TRAPPING MOISTURE NEAR THE SURFACE. PATCHY DENSE FOG IS
POSSIBLE NEAR DAWN.
OTHERWISE...SKIES WILL BECOME PARTLY CLOUDY...FROM WEST TO EAST.
THE AFTERNOON TEMPERATURES WILL BE RUNNING FROM 5 DEGREES ABOVE
NORMAL AT THE COAST...TO AROUND 10 DEGREES ACROSS THE PINEY HILLS.
FOR TONIGHT...FOG WILL BE RETURNING. OTHERWISE...THE OVERNIGHT
MINIMUMS WILL BE RUNNING FROM 10 TO 15 DEGREES ABOVE NORMAL.
OUTLOOK...
A STRONG CANADIAN FRONT WILL TRAVEL THROUGH THE FORECAST AREA
DURING THE OVERNIGHT HOURS ON SUNDAY.
NUMEROUS SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THIS SYSTEM.
THE FORECAST ENVIRONMENT WITHIN THE WARM SECTOR WEDGE (AS
DEPICTED BY THE GFS MODEL IS AS FOLLOWS)...
SIGNIFICANT LIFT...MESO-SYNOPTIC LIFT (ASSOCIATED THE ENTRANCE
REGION OF A SOUTHWESTERLY JET STREAK) WILL PHASE IN WITH THE
FRONTAL LIFT.
ADEQUATE MOISTURE...PRECIPITABLE WATER WILL BE NEAR 1.5 INCHES.
THE 1000-500 MB MEAN RELATIVE HUMIDITY WILL BE NEAR 80 PERCENT.
MARGINAL INSTABILITY AND MARGINAL SHEAR...CURRENTLY THE LIMITING
FACTOR FOR LONG-LIVED ORGANIZED THUNDERSTORMS.
21
&&
.PRELIMINARY POINT TEMPS/POPS...
KLCH 71 54 74 59 77 / 10 10 10 10 20
KBPT 72 55 74 61 76 / 10 10 10 10 20
KAEX 70 53 73 57 77 / 10 10 10 10 20
KLFT 71 56 74 58 76 / 10 10 10 10 20
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...NONE.
TX...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR THE FOLLOWING
ZONES: HARDIN...JEFFERSON...NORTHERN JASPER...NORTHERN
NEWTON...ORANGE...SOUTHERN JASPER...SOUTHERN NEWTON...TYLER.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DULUTH MN
1142 AM CST THU DEC 6 2012
.AVIATION...MAINLY MVFR-IFR CIGS ACROSS FORECAST AREA. THESE
CONDITIONS WILL REMAIN THROUGH 00Z-02Z ACROSS TAFS SITES AS THE
STRATUS IS STREAMING ACROSS THE REGION FROM THE NORTHWEST AND
EXTENDS BACK THE EASTERN DAKOTAS. AN AREA OF HIGH PRESSURE WILL
BUILD INTO THE FORECAST TONIGHT PUSHING THE CLOUDS OUT AND BRINGING
VFR CONDTIONS TO ALL TAF SITES BY 06Z.
&&
.PREV DISCUSSION... /ISSUED 945 AM CST THU DEC 6 2012/
UPDATE...
MADE SOME MINOR UPDATES TO FORECAST THROUGH TONIGHT. FIRST...THE
PCPN BAND IN THE EASTERN FA HAS BEEN MOVING QUICKER THAN THE
CURRENT FORECAST...SO LOWERED CHANCES FOR THE REST OF THE MORNING.
ALL PCPN SHOULD EXIT EAST OF THE FA BY NOON. THEN...ADJUSTED
TEMPERATURES THROUGH THE DAY TO REFLECT THAT TEMPERATURES MAY HOLD
STEADY OR SLIGHT RISE FOR A LITTLE BIT THIS MORNING...BUT THEN
FALL THROUGH THE REST OF THE DAY AS THE WNW WIND USHERS IN COLDER
AIR FROM CANADA.
PREV DISCUSSION... /ISSUED 551 AM CST THU DEC 6 2012/
AVIATION...12Z TAFS
AN AREA OF LIGHT RAIN...POSSIBLY MIXED WITH SOME SLEET...WAS
MOVING THROUGH NORTHWEST WISCONSIN...AND SHOULD END AT THE KHYR
TAF BETWEEN 14-15Z...AND EXIT NORTHWEST WISCONSIN BY LATE MORNING.
TEMPERATURES WERE ABOVE FREEZING...BUT GROUND TEMPERATURES WERE
AROUND FREEZING IN SPOTS. AN AREA OF MVFR CEILINGS WERE MOVING
QUICKLY SOUTHEAST...AND SHOULD AFFECT ALL TAF SITES TODAY. THERE
REMAINS QUESTIONS ON HOW LONG THEY WILL STICK AROUND THOUGH. THE
LATEST RAP SUGGESTS THEY WILL DIMINISH IN SPOTS MID TO LATE
AFTERNOON...BUT CONFIDENCE IN THIS IS LOW.
VWP`S INDICATE LLWS WILL REMAIN A PROBLEM UNTIL 15-16Z.
PREV DISCUSSION... /ISSUED 321 AM CST THU DEC 6 2012/
SHORT TERM...WEAKENING OCCLUDED FRONT IS PUSHING TOWARDS WRN CWA
WITH AREA OF WARM ADVECTION SPREADING LIGHT PRECIP ACROSS NE MN
ZONES. LIMITED EVAPORATIONAL COOLING IS OCCURRING AT SFC SINCE
PRECIP IS SO LIGHT. PTYPES HAVE BEEN MAINLY RAIN/SLEET/SNOW AT
THIS POINT. MAIN AXIS OF MORE SIGNIFICANT RADAR RETURNS IS
COLLOCATED WITH 70H THETAE AXIS THIS AXIS WILL SHIFT TO A KGNA TO
KDLH TO KMSP LINE BY 12Z. BRISK SOUTHERLY WINDS PUSHING SFC TEMPS
INTO LOW 40S OVER SWRN CWA AND PARTS OF NW WISC.
TODAY...AXIS OF WARM ADVECTION WILL MOVE QUICKLY ACROSS ERN CWA
WITH PRECIP ENDING IN NE MN BY MID MORNING. SECONDARY COLD FRONT
WITH AREA OF LOWER CLOUDS WILL PUSH ACROSS NE MN LATER THIS MORNING.
NAM12 COND PRESS DEFICITS HAVE A GOOD HANDLE ON THIS WITH AREA OF
LOW CLOUDS ALREADY IN SRN MANITOBA.
TONIGHT/TOMORROW...SFC HIGH WILL BUILD IN GRADUALLY FROM MANITOBA.
AS THIS IS OCCURRING...A SHORTWAVE TROF WILL PUSH INTO SRN
MINNESOTA FRIDAY. MID LVL FRONTOGENESIS IS FORECAST TO INCREASE
OVER CTRL/SRN MINNESOTA. INCREASING CLOUDS WILL DEVELOP OVER SRN
TIER OF CWA WITH SLIGHT CHC OF SNOW BY LATE FRIDAY.
EXTENDED...FRIDAY NIGHT THROUGH WEDNESDAY.
THIS PERIOD IS SHAPING UP TO BE AN ACTIVE ONE...WITH A COUPLE
DIFFERENT SYSTEMS BRINGING THE POTENTIAL FOR ACCUMULATING SNOW TO
THE NORTHLAND.
A WEAK SHORTWAVE WILL SLIDE THROUGH/NEAR THE NORTHLAND FRIDAY INTO
FRIDAY NIGHT...AND MAY CAUSE SOME LIGHT SNOW OVER THE SOUTHEASTERN
PORTION OF THE REGION...MAINLY NORTHWEST WISCONSIN. ANY SNOWFALL
FRIDAY NIGHT SHOULD BE LIGHT. HIGH PRESSURE THEN BRIEFLY BUILDS INTO
THE REGION LATE FRIDAY NIGHT AND MOVES THROUGH SATURDAY. SATURDAY
SHOULD BE DRY FOR MUCH OF THE AREA.
A STRONGER SHORTWAVE AND SURFACE LOW OR INVERTED TROUGH WILL AFFECT
THE NORTHLAND SATURDAY NIGHT INTO SUNDAY BRINGING THE POTENTIAL FOR
SNOW ACCUMULATIONS. THE MODELS ARE IN GENERAL AGREEMENT...BUT DO
SHOW SOME DIFFERENCES AS EXPECTED THIS FAR OUT. WE LEANED MORE
TOWARD THE ECMWF FOR MUCH OF THE DETAILS AT THIS TIME. SNOW SHOULD
DEVELOP SATURDAY NIGHT OVER MUCH OF THE CWA...MOST LIKELY OVER THE
WESTERN TWO THIRDS...WITH SNOW LIKELY ON SUNDAY ALL AREAS. 850MB
TEMPS LOOK WARMER THAN YESTERDAY`S RUN...BUT STILL COLD ENOUGH FOR
SOME LAKE ENHANCED SNOW FROM ABOUT TWO HARBORS ON NORTH. THE TWIN
PORTS COULD GET INTO SOME LAKE ENHANCED SNOW AS WELL IF WINDS ARE A
BIT MORE NORTH OF EAST THAN CURRENTLY FORECAST. WE`RE NOT READY TO
COMMIT TO SPECIFIC SNOW AMOUNTS AT THIS TIME...BUT THE THREAT FOR
SOME PLOWABLE SNOWFALL IS BECOMING MORE LIKELY.
THE SNOW SHOULD DIMINISH FOR MOST AREAS SUNDAY NIGHT...BUT AS WINDS
SWING AROUND TO THE NORTHWEST...A PERIOD OF LAKE EFFECT SNOW WILL BE
POSSIBLE IN THE SNOWBELT OF ASHLAND AND IRON COUNTIES. THIS SNOW
COULD BE HEAVY FOR A PERIOD. WINDS WILL BACK MONDAY...WITH LES
DIMINISHING IN THE AFTERNOON.
ANOTHER SHORTWAVE WILL BRING SOME LIGHT SNOW MONDAY NIGHT/TUESDAY TO
PORTIONS OF THE REGION. BOTH THE GFS AND ECMWF SHOW A STRONGER
SYSTEM NEXT WEDNESDAY...BUT DIFFER QUITE A BIT ON PLACEMENT OF THE
LOW. THIS SYSTEM WILL BEAR WATCHING AS THE ECMWF SHOWS A TIGHT
THERMAL GRADIENT ACROSS THE NORTHLAND...WHICH COULD LEAD TO SOME
SIGNIFICANT SNOWFALL IF IT VERIFIES.
TEMPERATURES WILL START OUT SATURDAY A COUPLE DEGREES ABOVE
NORMAL...THEN DROP QUITE A BIT BELOW NORMAL MONDAY BEHIND THE
DEPARTING SYSTEM THAT SHOULD BRING SNOW TO THE REGION. TEMPS WILL
THEN REMAIN A BIT BELOW NORMAL TUESDAY/WEDNESDAY.
&&
.POINT TEMPS/POPS...
DLH 39 18 26 16 / 0 0 0 10
INL 35 10 19 7 / 0 0 0 10
BRD 36 19 28 17 / 0 0 10 10
HYR 40 20 30 18 / 10 0 10 30
ASX 41 23 30 22 / 10 0 0 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 9 PM CST THIS EVENING FOR LSZ121-
140>143-146>148.
&&
$$
SHORT TERM...GROCHOCINSKI
LONG TERM....STEWART
AVIATION...STEWART
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
945 AM CST THU DEC 6 2012
.UPDATE...
MADE SOME MINOR UPDATES TO FORECAST THROUGH TONIGHT. FIRST...THE
PCPN BAND IN THE EASTERN FA HAS BEEN MOVING QUICKER THAN THE
CURRENT FORECAST...SO LOWERED CHANCES FOR THE REST OF THE MORNING.
ALL PCPN SHOULD EXIT EAST OF THE FA BY NOON. THEN...ADJUSTED
TEMPERATURES THROUGH THE DAY TO REFLECT THAT TEMPERATURES MAY HOLD
STEADY OR SLIGHT RISE FOR A LITTLE BIT THIS MORNING...BUT THEN
FALL THROUGH THE REST OF THE DAY AS THE WNW WIND USHERS IN COLDER
AIR FROM CANADA.
&&
.PREV DISCUSSION... /ISSUED 551 AM CST THU DEC 6 2012/
AVIATION...12Z TAFS
AN AREA OF LIGHT RAIN...POSSIBLY MIXED WITH SOME SLEET...WAS
MOVING THROUGH NORTHWEST WISCONSIN...AND SHOULD END AT THE KHYR
TAF BETWEEN 14-15Z...AND EXIT NORTHWEST WISCONSIN BY LATE MORNING.
TEMPERATURES WERE ABOVE FREEZING...BUT GROUND TEMPERATURES WERE
AROUND FREEZING IN SPOTS. AN AREA OF MVFR CEILINGS WERE MOVING
QUICKLY SOUTHEAST...AND SHOULD AFFECT ALL TAF SITES TODAY. THERE
REMAINS QUESTIONS ON HOW LONG THEY WILL STICK AROUND THOUGH. THE
LATEST RAP SUGGESTS THEY WILL DIMINISH IN SPOTS MID TO LATE
AFTERNOON...BUT CONFIDENCE IN THIS IS LOW.
VWP`S INDICATE LLWS WILL REMAIN A PROBLEM UNTIL 15-16Z.
PREV DISCUSSION... /ISSUED 321 AM CST THU DEC 6 2012/
SHORT TERM...WEAKENING OCCLUDED FRONT IS PUSHING TOWARDS WRN CWA
WITH AREA OF WARM ADVECTION SPREADING LIGHT PRECIP ACROSS NE MN
ZONES. LIMITED EVAPORATIONAL COOLING IS OCCURRING AT SFC SINCE
PRECIP IS SO LIGHT. PTYPES HAVE BEEN MAINLY RAIN/SLEET/SNOW AT
THIS POINT. MAIN AXIS OF MORE SIGNIFICANT RADAR RETURNS IS
COLLOCATED WITH 70H THETAE AXIS THIS AXIS WILL SHIFT TO A KGNA TO
KDLH TO KMSP LINE BY 12Z. BRISK SOUTHERLY WINDS PUSHING SFC TEMPS
INTO LOW 40S OVER SWRN CWA AND PARTS OF NW WISC.
TODAY...AXIS OF WARM ADVECTION WILL MOVE QUICKLY ACROSS ERN CWA
WITH PRECIP ENDING IN NE MN BY MID MORNING. SECONDARY COLD FRONT
WITH AREA OF LOWER CLOUDS WILL PUSH ACROSS NE MN LATER THIS MORNING.
NAM12 COND PRESS DEFICITS HAVE A GOOD HANDLE ON THIS WITH AREA OF
LOW CLOUDS ALREADY IN SRN MANITOBA.
TONIGHT/TOMORROW...SFC HIGH WILL BUILD IN GRADUALLY FROM MANITOBA.
AS THIS IS OCCURRING...A SHORTWAVE TROF WILL PUSH INTO SRN
MINNESOTA FRIDAY. MID LVL FRONTOGENESIS IS FORECAST TO INCREASE
OVER CTRL/SRN MINNESOTA. INCREASING CLOUDS WILL DEVELOP OVER SRN
TIER OF CWA WITH SLIGHT CHC OF SNOW BY LATE FRIDAY.
EXTENDED...FRIDAY NIGHT THROUGH WEDNESDAY.
THIS PERIOD IS SHAPING UP TO BE AN ACTIVE ONE...WITH A COUPLE
DIFFERENT SYSTEMS BRINGING THE POTENTIAL FOR ACCUMULATING SNOW TO
THE NORTHLAND.
A WEAK SHORTWAVE WILL SLIDE THROUGH/NEAR THE NORTHLAND FRIDAY INTO
FRIDAY NIGHT...AND MAY CAUSE SOME LIGHT SNOW OVER THE SOUTHEASTERN
PORTION OF THE REGION...MAINLY NORTHWEST WISCONSIN. ANY SNOWFALL
FRIDAY NIGHT SHOULD BE LIGHT. HIGH PRESSURE THEN BRIEFLY BUILDS INTO
THE REGION LATE FRIDAY NIGHT AND MOVES THROUGH SATURDAY. SATURDAY
SHOULD BE DRY FOR MUCH OF THE AREA.
A STRONGER SHORTWAVE AND SURFACE LOW OR INVERTED TROUGH WILL AFFECT
THE NORTHLAND SATURDAY NIGHT INTO SUNDAY BRINGING THE POTENTIAL FOR
SNOW ACCUMULATIONS. THE MODELS ARE IN GENERAL AGREEMENT...BUT DO
SHOW SOME DIFFERENCES AS EXPECTED THIS FAR OUT. WE LEANED MORE
TOWARD THE ECMWF FOR MUCH OF THE DETAILS AT THIS TIME. SNOW SHOULD
DEVELOP SATURDAY NIGHT OVER MUCH OF THE CWA...MOST LIKELY OVER THE
WESTERN TWO THIRDS...WITH SNOW LIKELY ON SUNDAY ALL AREAS. 850MB
TEMPS LOOK WARMER THAN YESTERDAY`S RUN...BUT STILL COLD ENOUGH FOR
SOME LAKE ENHANCED SNOW FROM ABOUT TWO HARBORS ON NORTH. THE TWIN
PORTS COULD GET INTO SOME LAKE ENHANCED SNOW AS WELL IF WINDS ARE A
BIT MORE NORTH OF EAST THAN CURRENTLY FORECAST. WE`RE NOT READY TO
COMMIT TO SPECIFIC SNOW AMOUNTS AT THIS TIME...BUT THE THREAT FOR
SOME PLOWABLE SNOWFALL IS BECOMING MORE LIKELY.
THE SNOW SHOULD DIMINISH FOR MOST AREAS SUNDAY NIGHT...BUT AS WINDS
SWING AROUND TO THE NORTHWEST...A PERIOD OF LAKE EFFECT SNOW WILL BE
POSSIBLE IN THE SNOWBELT OF ASHLAND AND IRON COUNTIES. THIS SNOW
COULD BE HEAVY FOR A PERIOD. WINDS WILL BACK MONDAY...WITH LES
DIMINISHING IN THE AFTERNOON.
ANOTHER SHORTWAVE WILL BRING SOME LIGHT SNOW MONDAY NIGHT/TUESDAY TO
PORTIONS OF THE REGION. BOTH THE GFS AND ECMWF SHOW A STRONGER
SYSTEM NEXT WEDNESDAY...BUT DIFFER QUITE A BIT ON PLACEMENT OF THE
LOW. THIS SYSTEM WILL BEAR WATCHING AS THE ECMWF SHOWS A TIGHT
THERMAL GRADIENT ACROSS THE NORTHLAND...WHICH COULD LEAD TO SOME
SIGNIFICANT SNOWFALL IF IT VERIFIES.
TEMPERATURES WILL START OUT SATURDAY A COUPLE DEGREES ABOVE
NORMAL...THEN DROP QUITE A BIT BELOW NORMAL MONDAY BEHIND THE
DEPARTING SYSTEM THAT SHOULD BRING SNOW TO THE REGION. TEMPS WILL
THEN REMAIN A BIT BELOW NORMAL TUESDAY/WEDNESDAY.
&&
.POINT TEMPS/POPS...
DLH 39 18 26 16 / 0 0 10 10
INL 35 10 19 7 / 0 0 10 10
BRD 36 19 28 17 / 0 0 20 10
HYR 40 20 30 18 / 10 0 10 30
ASX 41 23 30 22 / 10 0 10 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 9 PM CST THIS EVENING FOR LSZ121-
140>143-146>148.
&&
$$
SHORT TERM...GROCHOCINSKI
LONG TERM....STEWART
AREA FORECAST DISCUSSION
NWS DULUTH MN
551 AM CST THU DEC 6 2012
.AVIATION...12Z TAFS
AN AREA OF LIGHT RAIN...POSSIBLY MIXED WITH SOME SLEET...WAS
MOVING THROUGH NORTHWEST WISCONSIN...AND SHOULD END AT THE KHYR
TAF BETWEEN 14-15Z...AND EXIT NORTHWEST WISCONSIN BY LATE MORNING.
TEMPERATURES WERE ABOVE FREEZING...BUT GROUND TEMPERATURES WERE
AROUND FREEZING IN SPOTS. AN AREA OF MVFR CEILINGS WERE MOVING
QUICKLY SOUTHEAST...AND SHOULD AFFECT ALL TAF SITES TODAY. THERE
REMAINS QUESTIONS ON HOW LONG THEY WILL STICK AROUND THOUGH. THE
LATEST RAP SUGGESTS THEY WILL DIMINISH IN SPOTS MID TO LATE
AFTERNOON...BUT CONFIDENCE IN THIS IS LOW.
VWP`S INDICATE LLWS WILL REMAIN A PROBLEM UNTIL 15-16Z.
&&
.PREV DISCUSSION... /ISSUED 321 AM CST THU DEC 6 2012/
SHORT TERM...WEAKENING OCCLUDED FRONT IS PUSHING TOWARDS WRN CWA
WITH AREA OF WARM ADVECTION SPREADING LIGHT PRECIP ACROSS NE MN
ZONES. LIMITED EVAPORATIONAL COOLING IS OCCURRING AT SFC SINCE
PRECIP IS SO LIGHT. PTYPES HAVE BEEN MAINLY RAIN/SLEET/SNOW AT
THIS POINT. MAIN AXIS OF MORE SIGNIFICANT RADAR RETURNS IS
COLLOCATED WITH 70H THETAE AXIS THIS AXIS WILL SHIFT TO A KGNA TO
KDLH TO KMSP LINE BY 12Z. BRISK SOUTHERLY WINDS PUSHING SFC TEMPS
INTO LOW 40S OVER SWRN CWA AND PARTS OF NW WISC.
TODAY...AXIS OF WARM ADVECTION WILL MOVE QUICKLY ACROSS ERN CWA
WITH PRECIP ENDING IN NE MN BY MID MORNING. SECONDARY COLD FRONT
WITH AREA OF LOWER CLOUDS WILL PUSH ACROSS NE MN LATER THIS MORNING.
NAM12 COND PRESS DEFICITS HAVE A GOOD HANDLE ON THIS WITH AREA OF
LOW CLOUDS ALREADY IN SRN MANITOBA.
TONIGHT/TOMORROW...SFC HIGH WILL BUILD IN GRADUALLY FROM MANITOBA.
AS THIS IS OCCURRING...A SHORTWAVE TROF WILL PUSH INTO SRN
MINNESOTA FRIDAY. MID LVL FRONTOGENESIS IS FORECAST TO INCREASE
OVER CTRL/SRN MINNESOTA. INCREASING CLOUDS WILL DEVELOP OVER SRN
TIER OF CWA WITH SLIGHT CHC OF SNOW BY LATE FRIDAY.
EXTENDED...FRIDAY NIGHT THROUGH WEDNESDAY.
THIS PERIOD IS SHAPING UP TO BE AN ACTIVE ONE...WITH A COUPLE
DIFFERENT SYSTEMS BRINGING THE POTENTIAL FOR ACCUMULATING SNOW TO
THE NORTHLAND.
A WEAK SHORTWAVE WILL SLIDE THROUGH/NEAR THE NORTHLAND FRIDAY INTO
FRIDAY NIGHT...AND MAY CAUSE SOME LIGHT SNOW OVER THE SOUTHEASTERN
PORTION OF THE REGION...MAINLY NORTHWEST WISCONSIN. ANY SNOWFALL
FRIDAY NIGHT SHOULD BE LIGHT. HIGH PRESSURE THEN BRIEFLY BUILDS INTO
THE REGION LATE FRIDAY NIGHT AND MOVES THROUGH SATURDAY. SATURDAY
SHOULD BE DRY FOR MUCH OF THE AREA.
A STRONGER SHORTWAVE AND SURFACE LOW OR INVERTED TROUGH WILL AFFECT
THE NORTHLAND SATURDAY NIGHT INTO SUNDAY BRINGING THE POTENTIAL FOR
SNOW ACCUMULATIONS. THE MODELS ARE IN GENERAL AGREEMENT...BUT DO
SHOW SOME DIFFERENCES AS EXPECTED THIS FAR OUT. WE LEANED MORE
TOWARD THE ECMWF FOR MUCH OF THE DETAILS AT THIS TIME. SNOW SHOULD
DEVELOP SATURDAY NIGHT OVER MUCH OF THE CWA...MOST LIKELY OVER THE
WESTERN TWO THIRDS...WITH SNOW LIKELY ON SUNDAY ALL AREAS. 850MB
TEMPS LOOK WARMER THAN YESTERDAY`S RUN...BUT STILL COLD ENOUGH FOR
SOME LAKE ENHANCED SNOW FROM ABOUT TWO HARBORS ON NORTH. THE TWIN
PORTS COULD GET INTO SOME LAKE ENHANCED SNOW AS WELL IF WINDS ARE A
BIT MORE NORTH OF EAST THAN CURRENTLY FORECAST. WE`RE NOT READY TO
COMMIT TO SPECIFIC SNOW AMOUNTS AT THIS TIME...BUT THE THREAT FOR
SOME PLOWABLE SNOWFALL IS BECOMING MORE LIKELY.
THE SNOW SHOULD DIMINISH FOR MOST AREAS SUNDAY NIGHT...BUT AS WINDS
SWING AROUND TO THE NORTHWEST...A PERIOD OF LAKE EFFECT SNOW WILL BE
POSSIBLE IN THE SNOWBELT OF ASHLAND AND IRON COUNTIES. THIS SNOW
COULD BE HEAVY FOR A PERIOD. WINDS WILL BACK MONDAY...WITH LES
DIMINISHING IN THE AFTERNOON.
ANOTHER SHORTWAVE WILL BRING SOME LIGHT SNOW MONDAY NIGHT/TUESDAY TO
PORTIONS OF THE REGION. BOTH THE GFS AND ECMWF SHOW A STRONGER
SYSTEM NEXT WEDNESDAY...BUT DIFFER QUITE A BIT ON PLACEMENT OF THE
LOW. THIS SYSTEM WILL BEAR WATCHING AS THE ECMWF SHOWS A TIGHT
THERMAL GRADIENT ACROSS THE NORTHLAND...WHICH COULD LEAD TO SOME
SIGNIFICANT SNOWFALL IF IT VERIFIES.
TEMPERATURES WILL START OUT SATURDAY A COUPLE DEGREES ABOVE
NORMAL...THEN DROP QUITE A BIT BELOW NORMAL MONDAY BEHIND THE
DEPARTING SYSTEM THAT SHOULD BRING SNOW TO THE REGION. TEMPS WILL
THEN REMAIN A BIT BELOW NORMAL TUESDAY/WEDNESDAY.
&&
.POINT TEMPS/POPS...
DLH 37 21 26 16 / 10 0 10 10
INL 35 14 19 7 / 10 10 10 10
BRD 37 22 28 17 / 10 0 20 10
HYR 40 23 30 18 / 40 10 10 30
ASX 40 25 30 22 / 30 10 10 20
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 9 PM CST THIS EVENING FOR LSZ121-
140>143-146>148.
&&
$$
SHORT TERM...CANNON
LONG TERM....MELDE
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS BISMARCK ND
111 AM CST THU DEC 6 2012
.DISCUSSION...
SECONDARY COLD FRONT ADVECTING FROM NORTH TO SOUTH ACROSS NORTH
DAKOTA EARLY THIS THURSDAY MORNING. STRONG PRESSURE RISES ACROSS
THE NORTH HAS RESULTING IN WIND GUSTS UP TO 35KTS AT VARIOUS
OBSERVING SITES ACROSS THE NORTHWEST AND NORTH CENTRAL THE PAST
FEW HOURS. COULD BE EVEN STRONGER IF THE CENTER OF THE PRESSURE
RISE BUBBLE WAS FARTHER SOUTH...WITH BRANDON MANITOBA REPORTING A
WIND GUST OF 42KTS THE PAST HOUR. EXPECT THE WINDS TO TAPER OFF AS
THE PRESSURE RISE BUBBLE ADVECTS FARTHER TO THE EAST. WITH THE
INCREASE IN WINDS TEMPERATURES HAVE JUMPED SEVERAL DEGREES...BUT
DO COOL AS THE WINDS SLOWLY DECREASE. OVERALL WILL MAINTAIN
FORECAST LOWS PRETTY MUCH AS WAS INHERITED...WITH THE MAIN UPDATE
REGARDING TEMPERATURES ADJUSTING THE HOURLY TREND.
ALONG AND BEHIND THE COLD FRONT LOW STRATUS IS SURGING ACROSS
NORTHERN NORTH DAKOTA...ADVECTING SOUTH AND EAST ACROSS THE STATE.
INCREASED SKY COVER USING THE 05Z RAP AS A STARTING POINT. BOTH
THE RAP AND 12Z NAM MAINTAIN SOME SORT OF LOW STRATUS THROUGH 15Z
FROM NORTHWEST INTO MY SOUTH CENTRAL.
&&
.AVIATION...
STRATUS WRAPPING AROUND LOW MOVING SOUTH AND EAST THROUGH THE
FORECAST AREA IS ON A TRAJECTORY TO MISS AERODROMES OF SOUTHWEST
NORTH DAKOTA. MVFR CIGS CAN BE EXPECTED NOW THROUGH 15Z FOR KMOT
AND KISN...AND KBIS AND KJMS AFTER 09Z UNTIL 15Z.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...NH
AVIATION...HW/NH
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
907 PM EST FRI DEC 7 2012
.SYNOPSIS...
THE WEATHER PATTERN WILL REMAIN UNSETTLED THROUGH THE WEEKEND AS
WAVES OF LOW PRESSURE AND ASSOCIATED FRONTAL SYSTEMS MOVE ACROSS
THE GREAT LAKES AND THE OHIO VALLEY REGION. TEMPERATURES WILL
REMAIN ABOVE NORMAL THROUGH THE WEEKEND FOLLOWED BY MUCH COLDER
TEMPERATURES BY EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
LARGE AREA OF RAIN CONTINUES TO PROGRESS EASTWARD TONIGHT. UPDATE
WAS TO GRADUALLY DECREASE THE CHANCES OF RAIN AS IT EXITS THE
REGION THIS LATE EVENING AND LINGER A BAND OVER NORTHERN KY AND
SOUTHERN OH THROUGH EARLY TOMORROW. TWO DISTINCT BANDS OF
RAIN ARE NOTED. THE ONE EXTENDING NORTHEAST FROM RICHMOND IN TO
METRO DAYTON AND NORTH OF COLUMBUS APPEARS TO BE MORE IN TACT THAN
THE ONE SOUTH OF CHILLICOTHE. THE SOUTHERN AREA IS DEEMED A FOCUS
FOR FUTURE GENESIS OF RAIN OVERNIGHT AND EARLY TOMORROW. THE
NORTHERN ONE IS BEING PROGGED TO END IN THE NEXT FEW HOURS AS THE
SURFACE LOW TRACKS THROUGH THE REGION AND WINDS SHIFT WEST LATER
TONIGHT. UNTIL THIS HAPPENS...TEMPERATURES WILL BE NEAR STEADY-
STATE AND MAY CONTINUE TO SEE A SLIGHT RISE IN THE SOUTHEAST.
KEPT THE MENTION OF AREAS OF FOG FOR EVERYONE AS THE EXTREMELY
MOIST AIRMASS WILL REMAIN RIPE FOR LOW CLOUD DEVELOPMENT WHICH
COULD BE A SURFACE DECK IN SOME SPOTS.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
MODELS ARE IN FAIRLY DECENT AGREEMENT IN TERMS OF PLACEMENT...MOVEMENT
AND TIMING OF MAJOR SYNOPTIC SCALE SYSTEMS THROUGH THE SHORT TERM.
HAVE TAKEN A BLEND OF THE NAM...GFS AND ECMWF.
WAVE OF LOW PRESSURE WILL PUSH OFF TO THE NORTHEAST ON SATURDAY.
THIS WILL ALLOW A COLD FRONT TO SAG SOUTHEAST INTO THE REGION.
MODELS SUGGEST THAT THE BEST CHANCE OF PCPN ON SATURDAY WILL BE
ALONG AND AHEAD OF THE FRONT. THUS...HAVE LIKELY POPS GOING FOR
THE ERN/SRN LOCATIONS...MAINLY FOR THE FIRST PART OF THE DAY.
FOR SATURDAY NIGHT...IT LOOKS LIKE THE NRN LOCATIONS WILL HAVE A
RESPITE IN THE PCPN AS COLD FRONTAL SETTLES SOUTH OF THE OHIO
RIVER BEFORE MOVING BACK AS A WARM FRONT ON SUNDAY.
FOR SUNDAY INTO SUNDAY NIGHT...A MORE SIGNIFICANT S/WV IS EXPECTED
TO MOVE FROM THE CENTRAL PLAINS INTO THE GREAT LAKES. THIS
SCENARIO WILL PERTURB A WAVE OF LOW PRESSURE OVER THE MID MS VLY.
THIS PROCESS WILL PUSH OLD FRONTAL BOUNDARY NORTH THROUGH THE
REGION ON SUNDAY. RETURN MOISTURE AND A MODEST LOW LEVEL JET WILL
INCREASE SHOWERS FROM SOUTH TO NORTH DURING THE DAY. THERE SHOULD
BE ENOUGH INSTABILITY TO MENTION THUNDER. THE SFC LOW WILL DEEPEN
AS TI MOVE NE SUNDAY NIGHT...DRAGGING A COLD FRONT SE INTO THE
REGION. LARGE SCALE FRONTAL CONVERGENCE AND UPPER SUPPORT WILL
RESULT IN WIDESPREAD SHOWERS AND EMBEDDED THUNDERSTORMS.
THERE HAS BEEN SOME CONCERN ON HOW MUCH RAIN THE REGION WILL
RECEIVE THROUGH MONDAY DUE TO THE CUMULATIVE EFFECTS OF THE
WEATHER SYSTEMS MOVING THROUGH THE GREAT LAKES AND OHIO VALLEY. IT
APPEARS THAT AN ADDITIONAL 1 TO 2 INCHES ARE EXPECTED TONIGHT
THROUGH MONDAY WITH THE HEAVIEST AMOUNTS OCCURRING ALONG AND SE OF
I-71. GIVEN THAT NOVEMBER WAS DRY AND RIVER/STREAMS ARE STILL
FAIRLY LOW...BELIEVE THAT THE ADDITIONAL RAINFALL WILL NOT LEAD TO
ANY SUBSTANTIAL FLOODING ISSUES...ESPECIALLY WHEN IT COMES TO MAIN
STEM RIVERS. ANY POTENTIAL FLOODING WOULD LIKELY BE MESOSCALE
DRIVEN SUNDAY AFTERNOON AND NIGHT WHICH COULD LEAD TO MINOR ISSUES
IF THE SAME LOCATIONS RECEIVE ROUNDS OF MODERATE TO LOCALLY HEAVY
RAINFALL.
AS FOR TEMPERATURES...HAVE GENERALLY USED A NON-DIURNAL APPROACH
THROUGH THE PERIOD WITH A BLEND OF THE 2 M RAW NAM...GFS AND ECMWF.
IT WILL BE ABOVE NORMAL THROUGH THE WEEKEND WITH HIGHS IN THE 50S
TO THE LOWER 60S.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
A WET WEATHER PERIOD WILL COME TO AN END MONDAY...LEADING TO DRY
CONDITIONS AND INCREASING TEMPERATURES THROUGH THE REST OF THE WEEK.
THE OVERALL MODEL TREND IN THE PAST 24 HOURS HAS BEEN FOR A SLIGHTLY
EARLIER COLD FRONTAL PASSAGE ON MONDAY MORNING. THE TIMING
DIFFERENCES ARE STILL QUITE SMALL BETWEEN THE VARIOUS MODELS...SO
CONFIDENCE IN THE MONDAY FORECAST IS FAIRLY HIGH. BY 12Z...THE FRONT
WILL BE CLOSE TO CLEARING THE CWA...SO ANY THREAT FOR THUNDER WILL
BE LIMITED TO THE FIRST FEW HOURS AFTER DAYBREAK IN THE FAR
SOUTHEAST CORNER. TEMPERATURES WILL FALL THROUGH THE DAY...THANKS TO
THE COLD ADVECTION BEHIND THE FRONT...THOUGH TEMPS IN THE NORTHWEST
MAY END UP STEADY BY AFTERNOON (BEFORE THE TYPICAL DIURNAL
TEMPERATURE DROPS BEGIN).
THE FORECAST COMPLICATION FOR THIS WEATHER SYSTEM REMAINS WITH THE
BACK SIDE SHORTWAVE ON MONDAY NIGHT INTO TUESDAY. THE MID LEVEL
TROUGH THAT WILL FOLLOW THE COLD FRONT (AND ITS ATTACHED SURFACE LOW
MOVING THROUGH THE LOWER GREAT LAKES) HAS BEEN MODELED WITH A FEW
SUBTLE DIFFERENCES...PRESENTING SOME CHALLENGES IN THE PRECIPITATION
FORECAST ON THE BACK SIDE OF THE FRONT. THIS SECONDARY TROUGH AXIS
(AS OPPOSED TO THE ONE DRIVING THE SURFACE LOW) HAS CONSISTENTLY
BEEN DEPICTED WITH A GREATER SHARPNESS ON THE ECMWF (HIGHER
AMPLITUDE AND SHORTER WAVELENGTH). THE GFS DEPICTION IS MUCH
BROADER...AND DOES NOT ALLOW FOR ADDITIONAL SURFACE LOW PRESSURE
DEVELOPMENT OVER THE SOUTHERN APPALACHIANS LIKE THE ECMWF.
TEMPERATURES MONDAY NIGHT ARE CERTAINLY COLD ENOUGH TO SUPPORT
SNOW...SO IF THE ECMWF SOLUTION WERE TO VERIFY...SOME LIGHT
ACCUMULATIONS WOULD BE POSSIBLE.
THE LONGWAVE PATTERN WILL FLIP FROM TROUGH TO RIDGE OVER THE EASTERN
CONUS BY THE MIDDLE OF THE WEEK. THE LARGE SCALE PATTERN HAS BEEN
STABLE IN THE VARIOUS SOLUTIONS...AND THOUGH THE GFSE MEMBERS SHOW
SOME SPREAD IN THE NUMBERS...THE PATTERN IS IDENTICAL IN ALMOST ALL
CASES. THIS LEADS TO INCREASING CONFIDENCE IN DRY WEATHER WITH
SURFACE HIGH PRESSURE NOSING IN FROM THE SOUTH...AND BECOMING FIRMLY
ESTABLISHED OVER THE EASTERN CONUS BY THURSDAY. THIS WILL ALLOW FOR
SOUTHWESTERLY FLOW TO INCREASE TEMPERATURES OVER THE OHIO
VALLEY...GOING ABOVE NORMAL BY THE END OF THE WEEK.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
LARGE AREA OF RAIN MOVING ENE THROUGH OHIO WILL CONTINUE TO
PROGRESS THAT DIRECTION THIS EVEING. A DRY WEDGE WORKING INTO
METRO CINCINNATI MAY SPELL THE END OF PRECIPITATION FOR A WHILE IN
THIS LOCATION...AND THE HRRR IS SHOWING THAT THIS LULL WILL LAST
FOR A COUPLE OF HOURS. WINDS WILL SHIFT MORE SOUTHWEST AS THE
SURFACE LOW IS LOCATED IN SRN LERI TOWARDS DAYBREAK. ALL MODELS
COME IN GOOD AGREEMENT THAT THE PRECIP CHANCES AT THE TAF SITES
BEYOND 12Z ARE DIMINISHING SIGNIFICANTLY. AS WEST WINDS BRING IN
SOME DRIER AIR IN THE LATE MORNING...CIGS WILL LIFT AS VSBYS
BECOME VFR.
FOG...POTENTIALLY DENSE...WILL REMAIN IN THE FORECAST BUT I WAS
NOT CONFIDENT THAT THERE IS ENOUGH COLD AIR AROUND TO HAVE IT AS
THE PREVAILING WEATHER GROUP. I TOOK A 4 HOUR TEMPO GROUP IN THE
PREDAWN HOURS FOR DAY/ILN/CMH/LCK TO ACCOUNT FOR THE POTENTIAL FOR
DENSE FOG.
OUTLOOK...MVFR/IFR CIGS AND VSBYS POSSIBLE SATURDAY NIGHT INTO
MONDAY. A THUNDERSTORM IS POSSIBLE LATE SUNDAY AFTERNOON INTO
SUNDAY NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HICKMAN
NEAR TERM...FRANKS
SHORT TERM...HICKMAN
LONG TERM...HATZOS
AVIATION...FRANKS
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
651 PM EST FRI DEC 7 2012
.SYNOPSIS...
THE WEATHER PATTERN WILL REMAIN UNSETTLED THROUGH THE WEEKEND AS
WAVES OF LOW PRESSURE AND ASSOCIATED FRONTAL SYSTEMS MOVE ACROSS
THE GREAT LAKES AND THE OHIO VALLEY REGION. TEMPERATURES WILL
REMAIN ABOVE NORMAL THROUGH THE WEEKEND FOLLOWED BY MUCH COLDER
TEMPERATURES BY EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
LOCAL AND MOSAIC RADAR CONTINUE TO SHOW RAIN ACROSS THE REGION.
THIS PCPN WAS THE RESULT OF A MOIST AIRMASS IN PLACE COUPLED WITH
LOW LEVEL JET FORCING AND WEAK EMBEDDED DISTURBANCES WITHIN THE
WEST/SOUTHWEST FLOW ALOFT. FOR TONIGHT...A WEAK AREA OF LOW
PRESSURE IS FORECAST TO RIPPLE ALONG A FRONTAL BOUNDARY NEAR OUR
NORTHWEST...BEING PERTURBED BY A LITTLE STRONGER S/WV PUSHES ACRS
THE GREAT LAKES. HAVE GONE WITH MAINLY CATEGORICAL POPS THIS
EVENING...ALTHOUGH THE LATEST HRRR SUGGESTS THAT WIDESPREAD PCPN
MAY BRIEFLY TAPER LATE THIS EVENING/EARLY MORNING BEFORE THE WAVE
OF LOW PRESSURE ARRIVES AND BRINGS ANOTHER ROUND OF RAIN. WILL
CONTINUE TO MONITOR FOR POTENTIAL SHORT TERM ENHANCEMENT. THE
OTHER WEATHER ISSUE TONIGHT WILL BE FOG POTENTIAL. DENSE FOG
FORMED LAST NIGHT ACRS THE WHITEWATER AND MIAMI RIVER VALLEYS AS
WELL AS INTO CENTRAL OHIO. THIS COULD HAPPEN AGAIN ANYWHERE ACRS
THE AREA TONIGHT IF PCPN TAPERS OFF LONG ENOUGH AND WINDS STAY
RELATIVELY LIGHT. DUE TO UNCERTAINTY...HAVE PLACED AREAS OF FOG IN
THE FORECAST AND UPDATED THE HWO PRODUCT FOR POTENTIAL DENSE FOG
OVERNIGHT IF CONDITIONS COME TOGETHER. TEMPERATURES TONIGHT WILL
EITHER REMAIN STEADY STATE OR SLOWLY RISE AHEAD OF THE APPROACHING
LOW PRESSURE WAVE.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
MODELS ARE IN FAIRLY DECENT AGREEMENT IN TERMS OF PLACEMENT...MOVEMENT
AND TIMING OF MAJOR SYNOPTIC SCALE SYSTEMS THROUGH THE SHORT TERM.
HAVE TAKEN A BLEND OF THE NAM...GFS AND ECMWF.
WAVE OF LOW PRESSURE WILL PUSH OFF TO THE NORTHEAST ON SATURDAY.
THIS WILL ALLOW A COLD FRONT TO SAG SOUTHEAST INTO THE REGION.
MODELS SUGGEST THAT THE BEST CHANCE OF PCPN ON SATURDAY WILL BE
ALONG AND AHEAD OF THE FRONT. THUS...HAVE LIKELY POPS GOING FOR
THE ERN/SRN LOCATIONS...MAINLY FOR THE FIRST PART OF THE DAY.
FOR SATURDAY NIGHT...IT LOOKS LIKE THE NRN LOCATIONS WILL HAVE A
RESPITE IN THE PCPN AS COLD FRONTAL SETTLES SOUTH OF THE OHIO
RIVER BEFORE MOVING BACK AS A WARM FRONT ON SUNDAY.
FOR SUNDAY INTO SUNDAY NIGHT...A MORE SIGNIFICANT S/WV IS EXPECTED
TO MOVE FROM THE CENTRAL PLAINS INTO THE GREAT LAKES. THIS
SCENARIO WILL PERTURB A WAVE OF LOW PRESSURE OVER THE MID MS VLY.
THIS PROCESS WILL PUSH OLD FRONTAL BOUNDARY NORTH THROUGH THE
REGION ON SUNDAY. RETURN MOISTURE AND A MODEST LOW LEVEL JET WILL
INCREASE SHOWERS FROM SOUTH TO NORTH DURING THE DAY. THERE SHOULD
BE ENOUGH INSTABILITY TO MENTION THUNDER. THE SFC LOW WILL DEEPEN
AS TI MOVE NE SUNDAY NIGHT...DRAGGING A COLD FRONT SE INTO THE
REGION. LARGE SCALE FRONTAL CONVERGENCE AND UPPER SUPPORT WILL
RESULT IN WIDESPREAD SHOWERS AND EMBEDDED THUNDERSTORMS.
THERE HAS BEEN SOME CONCERN ON HOW MUCH RAIN THE REGION WILL
RECEIVE THROUGH MONDAY DUE TO THE CUMULATIVE EFFECTS OF THE
WEATHER SYSTEMS MOVING THROUGH THE GREAT LAKES AND OHIO VALLEY. IT
APPEARS THAT AN ADDITIONAL 1 TO 2 INCHES ARE EXPECTED TONIGHT
THROUGH MONDAY WITH THE HEAVIEST AMOUNTS OCCURRING ALONG AND SE OF
I-71. GIVEN THAT NOVEMBER WAS DRY AND RIVER/STREAMS ARE STILL
FAIRLY LOW...BELIEVE THAT THE ADDITIONAL RAINFALL WILL NOT LEAD TO
ANY SUBSTANTIAL FLOODING ISSUES...ESPECIALLY WHEN IT COMES TO MAIN
STEM RIVERS. ANY POTENTIAL FLOODING WOULD LIKELY BE MESOSCALE
DRIVEN SUNDAY AFTERNOON AND NIGHT WHICH COULD LEAD TO MINOR ISSUES
IF THE SAME LOCATIONS RECEIVE ROUNDS OF MODERATE TO LOCALLY HEAVY
RAINFALL.
AS FOR TEMPERATURES...HAVE GENERALLY USED A NON-DIURNAL APPROACH
THROUGH THE PERIOD WITH A BLEND OF THE 2 M RAW NAM...GFS AND ECMWF.
IT WILL BE ABOVE NORMAL THROUGH THE WEEKEND WITH HIGHS IN THE 50S
TO THE LOWER 60S.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
A WET WEATHER PERIOD WILL COME TO AN END MONDAY...LEADING TO DRY
CONDITIONS AND INCREASING TEMPERATURES THROUGH THE REST OF THE WEEK.
THE OVERALL MODEL TREND IN THE PAST 24 HOURS HAS BEEN FOR A SLIGHTLY
EARLIER COLD FRONTAL PASSAGE ON MONDAY MORNING. THE TIMING
DIFFERENCES ARE STILL QUITE SMALL BETWEEN THE VARIOUS MODELS...SO
CONFIDENCE IN THE MONDAY FORECAST IS FAIRLY HIGH. BY 12Z...THE FRONT
WILL BE CLOSE TO CLEARING THE CWA...SO ANY THREAT FOR THUNDER WILL
BE LIMITED TO THE FIRST FEW HOURS AFTER DAYBREAK IN THE FAR
SOUTHEAST CORNER. TEMPERATURES WILL FALL THROUGH THE DAY...THANKS TO
THE COLD ADVECTION BEHIND THE FRONT...THOUGH TEMPS IN THE NORTHWEST
MAY END UP STEADY BY AFTERNOON (BEFORE THE TYPICAL DIURNAL
TEMPERATURE DROPS BEGIN).
THE FORECAST COMPLICATION FOR THIS WEATHER SYSTEM REMAINS WITH THE
BACK SIDE SHORTWAVE ON MONDAY NIGHT INTO TUESDAY. THE MID LEVEL
TROUGH THAT WILL FOLLOW THE COLD FRONT (AND ITS ATTACHED SURFACE LOW
MOVING THROUGH THE LOWER GREAT LAKES) HAS BEEN MODELED WITH A FEW
SUBTLE DIFFERENCES...PRESENTING SOME CHALLENGES IN THE PRECIPITATION
FORECAST ON THE BACK SIDE OF THE FRONT. THIS SECONDARY TROUGH AXIS
(AS OPPOSED TO THE ONE DRIVING THE SURFACE LOW) HAS CONSISTENTLY
BEEN DEPICTED WITH A GREATER SHARPNESS ON THE ECMWF (HIGHER
AMPLITUDE AND SHORTER WAVELENGTH). THE GFS DEPICTION IS MUCH
BROADER...AND DOES NOT ALLOW FOR ADDITIONAL SURFACE LOW PRESSURE
DEVELOPMENT OVER THE SOUTHERN APPALACHIANS LIKE THE ECMWF.
TEMPERATURES MONDAY NIGHT ARE CERTAINLY COLD ENOUGH TO SUPPORT
SNOW...SO IF THE ECMWF SOLUTION WERE TO VERIFY...SOME LIGHT
ACCUMULATIONS WOULD BE POSSIBLE.
THE LONGWAVE PATTERN WILL FLIP FROM TROUGH TO RIDGE OVER THE EASTERN
CONUS BY THE MIDDLE OF THE WEEK. THE LARGE SCALE PATTERN HAS BEEN
STABLE IN THE VARIOUS SOLUTIONS...AND THOUGH THE GFSE MEMBERS SHOW
SOME SPREAD IN THE NUMBERS...THE PATTERN IS IDENTICAL IN ALMOST ALL
CASES. THIS LEADS TO INCREASING CONFIDENCE IN DRY WEATHER WITH
SURFACE HIGH PRESSURE NOSING IN FROM THE SOUTH...AND BECOMING FIRMLY
ESTABLISHED OVER THE EASTERN CONUS BY THURSDAY. THIS WILL ALLOW FOR
SOUTHWESTERLY FLOW TO INCREASE TEMPERATURES OVER THE OHIO
VALLEY...GOING ABOVE NORMAL BY THE END OF THE WEEK.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
LARGE AREA OF RAIN MOVING ENE THROUGH OHIO WILL CONTINUE TO
PROGRESS THAT DIRECTION THIS EVEING. A DRY WEDGE WORKING INTO
METRO CINCINNATI MAY SPELL THE END OF PRECIPITATION FOR A WHILE IN
THIS LOCATION...AND THE HRRR IS SHOWING THAT THIS LULL WILL LAST
FOR A COUPLE OF HOURS. WINDS WILL SHIFT MORE SOUTHWEST AS THE
SURFACE LOW IS LOCATED IN SRN LERI TOWARDS DAYBREAK. ALL MODELS
COME IN GOOD AGREEMENT THAT THE PRECIP CHANCES AT THE TAF SITES
BEYOND 12Z ARE DIMINISHING SIGNIFICANTLY. AS WEST WINDS BRING IN
SOME DRIER AIR IN THE LATE MORNING...CIGS WILL LIFT AS VSBYS
BECOME VFR.
FOG...POTENTIALLY DENSE...WILL REMAIN IN THE FORECAST BUT I WAS
NOT CONFIDENT THAT THERE IS ENOUGH COLD AIR AROUND TO HAVE IT AS
THE PREVAILING WEATHER GROUP. I TOOK A 4 HOUR TEMPO GROUP IN THE
PREDAWN HOURS FOR DAY/ILN/CMH/LCK TO ACCOUNT FOR THE POTENTIAL FOR
DENSE FOG.
OUTLOOK...MVFR/IFR CIGS AND VSBYS POSSIBLE SATURDAY NIGHT INTO
MONDAY. A THUNDERSTORM IS POSSIBLE LATE SUNDAY AFTERNOON INTO
SUNDAY NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HICKMAN
NEAR TERM...HICKMAN
SHORT TERM...HICKMAN
LONG TERM...HATZOS
AVIATION...FRANKS
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
425 AM EST THU DEC 6 2012
.SYNOPSIS...
HIGH PRESSURE WILL RETURN OVER THE AREA TODAY AND FRIDAY. EXPECT
THIS HIGH TO BECOME CENTERED OFF THE EAST COAST WHICH WILL RESULT IN
A STRONG SOUTHERLY FLOW OF WARM AND MOIST AIR OVER THE WEEKEND. A
COLD FRONT WITH MORE ACTIVE WEATHER WILL ARRIVE ON MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 425 AM EST THURSDAY...CLOUDS CONTINUE TO PROGRESS SLOWLY
NORTHWARD ACROSS THE FORECAST AREA EARLY THIS MORNING. ONLY THE
NORTHEAST MOST FRINGE OF THE FA IS CLEAR ATTM...AND THOSE LOCATIONS
WILL SEE CLOUD COVER INVADE OVER THE NEXT 1 TO 2 HOURS. THE GSP
WSR-88D IS SHOWING SOME VERY LIGHT RETURNS OVER THE UPSTATE AND NE
GA ATTM. LOCAL OBSERVATIONS HAVE NOT REPORTED ANY PRECIPITATION...SO
WHAT IS FALLING IS LIKELY TO BE SPOTTY AND LIGHT. CLOUD BASES ARE
FAIRLY HIGH AND I/D IMAGINE THE DROPLET DIAMETERS WILL BE SMALL THIS
MORNING. SO A LOT OF WHAT LITTLE IS FALLING IS LIKELY TO EVAPORATE
BEFORE HITTING THE GROUND. STILL...I/VE ADDED SPRINKLES ACROSS THE
UPSTATE AND NE GA FOR SEVERAL HOURS THIS MORNING TO ACCOUNT FOR A
LITTLE LIGHT PCPN.
PREVIOUS DISCUSSION...
COLD AIR DAMMING CONTINUES TO ESTABLISH ITSELF OVER THE FORECAST
AREA EARLY THIS MORNING. THE LLVL AIRMASS IS QUITE DRY AND THE CLOUD
BASES ARE RANGING FROM ABOUT 8000 FEET OVER THE NRN ZONES TO AROUND
3000 FEET OVER THE SOUTHWEST MOST PART OF THE FORECAST AREA. THIS
MAKES SENSE OWING TO THE SLOPING NATURE OF LLVL RIDGE. LLVL WARM
ADVECTION IS WEAK THROUGHOUT THE DAY OVER THE REGION...BUT
OROGRAPHIC ASCENT SHOULD BE SUFFICIENT TO KEEP PATCHY LIGHT RAN AND
DRIZZLE FALLING OVER THE MTNS. THIS IS ESPECIALLY TRUE AS THE
ATMOSPHERE IS SATURATED TO OVER 10KFT ON MODEL SOUNDINGS OVER THE
MTNS TODAY. NOT LOOKING FOR LARGE DIURNAL RANGES WITH THE CLOUD
COVER TODAY. IN FACT...LOW LEVEL COLD ADVECTION MAY ACTUALLY LOWER
TEMPERATURES THROUGH THE MORNING HOURS BEFORE THERE IS SOME RECOVERY
IN THE AFTN.
OVERNIGHT THE LLVL FLOW STRENGTHENS A LITTLE OVER THE CAD BNDRY AS
THE H8 RIDGE MOVES A LITTLE FURTHER OFF THE COAST. NAM CROSS
SECTIONS SHOW GOOD LLVL UVV/S DEVELOPING ALONG THE BLUE RIDGE
MOUNTAINS STARTING AROUND MIDNIGHT. THE SREF POPS ALONG THE
ESCARPMENT INCREASE INTO THE CATEGORICAL RANGE AND THE POPS ARE ALSO
HIGH ON THE NAM. THE GFS PCPN FIELDS DON/T MAKE A LOT OF SENSE AS IT
HAS MOST OF THE PCPN FALLING OUT ACROSS THE PIEDMONT OVER THE HEART
OF THE CAD BNDRY. THEREFORE...I FOLLOWED THE NAM/SREF CLOSELY
OVERNIGHT. WHILE QPF WON/T BE HIGH...THERE WILL ALMOST CERTAINLY BE
RAIN/DRIZZLE ALONG THE BLUE RIDGE AND ADJACENT FOOTHILLS AREAS LATER
TONIGHT AND I/VE INCREASED POPS INTO THE HIGH CHANCE TO LOW LIKELY
RANGE OVER THESE AREAS. NEAR THE TN LINE DOWNSLOPE FLOW WILL KEEP
CONDITIONS DRY. I ALSO WOULD EXPECT LITTLE IN THE WAY OF PCPN ACROSS
THE PIEDMONT WHERE LLVL OMEGA IS ALSO QUITE WEAK.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 230 AM THURSDAY...FRIDAY...SFC HIGH PRESSURE WILL CONTINUE TO
RIDGE SW ACROSS THE FORECAST AREA...RESULTING IN LIGHT NE SFC WINDS.
FORECAST SOUNDINGS INDICATE THAT TEMPERATURE AND DEWPOINT PROFILES
WILL REMAIN NEARLY MATCHED FROM H950 TO H750 ACROSS THE REGION. 295K
SW WINDS SHOULD RESULT IN ISENTROPIC LIFT TO STRENGTHEN AND LIFT
NORTHWARD THROUGH MID DAY FRIDAY. THE COMBINATION OF THE MOISTURE
AND LOW LIFT SHOULD SUPPORT -RA OR SPRINKLES ACROSS THE
CWA...ESPECIALLY NEAR THE EAST FACING SLOPES OF THE MTNS. LIGHT QPF
IS FEATURED IN THE NAM...GFS...AND ECMWF DURING THE MORNING. IN
ADDITION...THE SREF PLUMES INDICATE LIGHT RAINFALL TO OCCUR DURING
THE MORNING ISENTROPIC LIFT. I WILL INCREASE POP WELL INTO THE CHC
RANGE ACROSS THE EAST FACING SLOPES AND ADJACENT FOOTHILLS...WITH
SCHC ELSEWHERE. THE LLVL LIFT APPEARS TO WEAKEN DURING THE AFTERNOON
HOURS...HOWEVER...WEAK SYNOPTIC SCALE FORCING INCREASES WITH THE
APPROACH OF A MID LEVEL TROF...SUPPORTING SCHC POPS EAST OF THE MTNS
WITH MTN CHC. GIVEN THE THICK CLOUD COVER...NE SFC WIND...AND
PERIODS OF -RA...FRI TEMPS MAY ONLY WARM 3 TO 5 DEGREES OVER VALUES
EXPECTED FOR TODAY.
FRIDAY NIGHT THROUGH SATURDAY NIGHT...SFC RIDGING ACROSS THE CWA
WILL GRADUALLY WEAKEN AND ISENTROPIC LIFT WILL DISSIPATE. FORECAST
SOUNDINGS INDICATE THAT LLVL CLOUD COVER WILL GRADUALLY THIN WITH
THE LOSS OF LIFT. HOWEVER...WINDS WILL LIKELY SHIFT TO THE
SOUTH-SOUTHWEST AS THE HIGH WEAKENS AND LOW PRESSURE DEVELOPS OVER
THE MID MISSISSIPPI VALLEY. LLVL THICKNESSES AND TEMPERATURE
PROFILES WILL REMAIN VERY MILD THROUGH THE PERIOD...SUPPORTING MIN
TEMPS SATURDAY AND SUNDAY AROUND 10 DEGREES ABOVE NORMAL. HIGHS ON
SATURDAY MAY RANGE FROM 10 TO 15 DEGREES ABOVE NORMAL...ESPECIALLY
IF CLOUDS BREAK. POPS WILL REMAIN LIMITED GIVEN THE LACK OF
FORCING...HOWEVER...SCT MTN -RA IS POSSIBLE UNDER BROAD MID LEVEL
CYCLONIC FLOW.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 230 AM THURSDAY...THE MEDIUM RANGE MODELS ARE IN GOOD
AGREEMENT ON THE PROGRESSION OF THE COLD FRONT AND EXPANSION OF HIGH
PRESSURE BEHIND THE FRONT IN MID WEEK. STARTING AT 12Z SUNDAY...
HIGH PRESSURE CENTERED GENERALLY NEAR BERMUDA WITH GOOD FETCH OF
SOUTHERLY FLOW AND SHORTWAVE PROGRESSING ACROSS NORTHERN PLAINS. A
BIT MORE FAVORABLE FOR CONVECTION IN THE NC MOUNTAINS AND BROUGHT
POPS UP TO VERY LOW CHANCE SUNDAY AFTERNOON NEAR LAKE TOXAWAY OVER
THE CULLOWHEE AREA. GFS CAPE FOR SUNDAY AFTERNOON IS QUITE LOW IN
THE 20 TO 40 JOULES AND ECMWF IS HIGHER IN THE 100 TO 300 RANGE.
THE FRONT IS WELL DEFINED LATE SUNDAY NIGHT AND MOVING EAST. THE GFS
CONTINUES TO BE SLIGHTLY MORE PROGRESSIVE IN MOVING THE FRONT EAST
ACROSS THE AREA WITH THE NEW ECMWF LAGGING THE PRECIP BACK...FROM
MID ALABAMA TO FAR EAST TENNESSEE AT 00Z TUESDAY. CAPES ARE RATHER
LOW AND WIND SHEAR CONTINUES TO BE UP FOR MONDAY AFTERNOON. GFS
CAPES MONDAY AFTERNOON BEST ALONG AND EAST OF I-77 WITH 100 TO 200
AND 850MB WIND AROUND 40KTS AND 700MB WIND 65KTS NEAR CHARLOTTE. NEW
ECMWF CAPES AROUND 200 JUST EAST OF CHARLOTTE MONDAY AFTERNOON. THE
CANADIAN MODEL HAS FRONTAL PRECIP STRAIGHT UP THE APPALACHIAN CHAIN
AT 00Z TUESDAY. AFTER USING GFS CAPE ONLY SHOWED A LITTLE THUNDER IN
THE CHARLOTTE AREA MONDAY AFTERNOON. AT THIS POINT...THAT SEEMS TO
BE THE PLACE TO WATCH BUT ALL COULD CHANGE AS THAT IS STILL DAY 5 OF
THE FORECAST.
AS THE FRONT MOVES EAST LATE MONDAY NIGHT INTO EARLY TUESDAY...VERY
BRIEF WRAP AROUND MOISTURE LINGERS IN THE NC MOUNTAINS. THAT ONLY
LASTS 3 TO 6 HOURS AND LONGEST ON THE ECMWF WHERE IT HANGS ON TO MID
DAY TUESDAY. SURFACE HIGH CENTERED OVER NC EARLY WEDNESDAY AS THE
NEXT SIGNIFICANT SHORTWAVE CROSSES TEXAS AND OKLAHOMA MOVING EAST.
THIS GENERATES A SIGNIFICANT GULF OF MEXICO LOW PRESSURE WEDNESDAY
NIGHT ON THE GFS AND MOVES IT NORTHEAST FROM MISS DELTA REGION. THE
ECMWF IS MUCH LESS ROBUST. THE GFS AND ECMWF HAS LIGHT PRECIP MOVING
UP OVER NE GA AND UPSTATE AT 12Z THURSDAY OF NEXT WEEK. KEPT POPS
BELOW SLIGHT AT THE END OF DAY 7 AND FUTURE SHIFTS WILL EVALUATE.
&&
.AVIATION /10Z THURSDAY THROUGH MONDAY/...
AT KCLT...WINDS WILL BE OUT OF THE NE THROUGH THE VALID PERIOD OF
THE TAF. SPEEDS WILL INCREASE TO AROUND 10 KTS LATE TONIGHT. A CIG
UP AROUND 8KFT SHOULD MOVE IN FROM THE WEST HERE SHORTLY. SOME OF
THE MODELS HAVE MVFR CIGS DEVELOPING AROUND 12 UTC AS A SECONDARY
COLD FRONT COMES THROUGH. THE RUC BUFKIT SOUNDINGS EVEN IMPLY
SOMETHING ON THE BORDER WITH IFR. WHILE THE MOS ISN/T SHOWING
ANYTHING...THERE IS ENUF RAW MODEL OUTPUT WITH MVFR CIGS THAT I/VE
ADDED A 1700 FOOT CIG FROM 11-14 UTC. AFTER THAT THE CIGS SHOULD
RISE AGAIN.
ELSEWHERE...CLOUDS WILL BE MAINTAINED OVER A DOME OF COOL...DRY AIR
AT THE SURFACE. FOR THE REST OF THE NIGHT CIGS SHOULD STAY IN THE
VFR RANGE AT ALL TAF SITES. WINDS WILL BE OUT OF THE NE THROUGH THE
VALID PERIOD OF THE TAFS OVER THE FOOTHILLS AND PIEDMONT AND VERY
LIGHT OUT OF THE SE UP THE FRENCH BROAD VALLEY. CIGS ARE EXPECTED TO
LOWER INTO THE HIGH END OF THE MVFR RANGE BY MID TO LATE MORNING ON
THURSDAY. A FEW SPRINKLES OR LIGHT SHOWERS ARE POSSIBLE OVER THE
UPSTATE TONIGHT AND AT KAVL ON THURSDAY.
OUTLOOK...RESTRICTIVE CIGS ARE EXPECTED LATE THURSDAY NIGHT THROUGH
SATURDAY MORNING. THE REGION WILL MOVE INTO A WARM SECTOR AFTER THAT
WITH GENERALLY FAIR CONDITIONS LATER SATURDAY AND SUNDAY.
HOWEVER...PATCHY FOG AND STRATUS WILL BE POSSIBLE BOTH SUNDAY AND
MONDAY MORNINGS. A STRONG COLD FRONT WILL CROSS THE REGION ON
MONDAY...ACCOMPANIED BY SHOWERS AND THUNDERSTORMS ALONG WITH GUSTY
WINDS.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...MCAVOY
SHORT TERM...NED
LONG TERM...DEO
AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
248 AM EST THU DEC 6 2012
.SYNOPSIS...
HIGH PRESSURE WILL RETURN OVER THE AREA TODAY AND FRIDAY. EXPECT
THIS HIGH TO BECOME CENTERED OFF THE EAST COAST WHICH WILL RESULT IN
A STRONG SOUTHERLY FLOW OF WARM AND MOIST AIR OVER THE WEEKEND. A
COLD FRONT WITH MORE ACTIVE WEATHER WILL ARRIVE ON MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
COLD AIR DAMMING CONTINUES TO ESTABLISH ITSELF OVER THE FORECAST
AREA EARLY THIS MORNING. THE LLVL AIRMASS IS QUITE DRY AND THE CLOUD
BASES ARE RANGING FROM ABOUT 8000 FEET OVER THE NRN ZONES TO AROUND
3000 FEET OVER THE SOUTHWEST MOST PART OF THE FORECAST AREA. THIS
MAKES SENSE OWING TO THE SLOPING NATURE OF LLVL RIDGE. LLVL WARM
ADVECTION IS WEAK THROUGHOUT THE DAY OVER THE REGION...BUT
OROGRAPHIC ASCENT SHOULD BE SUFFICIENT TO KEEP PATCHY LIGHT RAN AND
DRIZZLE FALLING OVER THE MTNS. THIS IS ESPECIALLY TRUE AS THE
ATMOSPHERE IS SATURATED TO OVER 10KFT ON MODEL SOUNDINGS OVER THE
MTNS TODAY. NOT LOOKING FOR LARGE DIURNAL RANGES WITH THE CLOUD
COVER TODAY. IN FACT...LOW LEVEL COLD ADVECTION MAY ACTUALLY LOWER
TEMPERATURES THROUGH THE MORNING HOURS BEFORE THERE IS SOME RECOVERY
IN THE AFTN.
OVERNIGHT THE LLVL FLOW STRENGTHENS A LITTLE OVER THE CAD BNDRY AS
THE H8 RIDGE MOVES A LITTLE FURTHER OFF THE COAST. NAM CROSS
SECTIONS SHOW GOOD LLVL UVV/S DEVELOPING ALONG THE BLUE RIDGE
MOUNTAINS STARTING AROUND MIDNIGHT. THE SREF POPS ALONG THE
ESCARPMENT INCREASE INTO THE CATEGORICAL RANGE AND THE POPS ARE ALSO
HIGH ON THE NAM. THE GFS PCPN FIELDS DON/T MAKE A LOT OF SENSE AS IT
HAS MOST OF THE PCPN FALLING OUT ACROSS THE PIEDMONT OVER THE HEART
OF THE CAD BNDRY. THEREFORE...I FOLLOWED THE NAM/SREF CLOSELY
OVERNIGHT. WHILE QPF WON/T BE HIGH...THERE WILL ALMOST CERTAINLY BE
RAIN/DRIZZLE ALONG THE BLUE RIDGE AND ADJACENT FOOTHILLS AREAS LATER
TONIGHT AND I/VE INCREASED POPS INTO THE HIGH CHANCE TO LOW LIKELY
RANGE OVER THESE AREAS. NEAR THE TN LINE DOWNSLOPE FLOW WILL KEEP
CONDITIONS DRY. I ALSO WOULD EXPECT LITTLE IN THE WAY OF PCPN ACROSS
THE PIEDMONT WHERE LLVL OMEGA IS ALSO QUITE WEAK.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 230 AM THURSDAY...FRIDAY...SFC HIGH PRESSURE WILL CONTINUE TO
RIDGE SW ACROSS THE FORECAST AREA...RESULTING IN LIGHT NE SFC WINDS.
FORECAST SOUNDINGS INDICATE THAT TEMPERATURE AND DEWPOINT PROFILES
WILL REMAIN NEARLY MATCHED FROM H950 TO H750 ACROSS THE REGION. 295K
SW WINDS SHOULD RESULT IN ISENTROPIC LIFT TO STRENGTHEN AND LIFT
NORTHWARD THROUGH MID DAY FRIDAY. THE COMBINATION OF THE MOISTURE
AND LOW LIFT SHOULD SUPPORT -RA OR SPRINKLES ACROSS THE
CWA...ESPECIALLY NEAR THE EAST FACING SLOPES OF THE MTNS. LIGHT QPF
IS FEATURED IN THE NAM...GFS...AND ECMWF DURING THE MORNING. IN
ADDITION...THE SREF PLUMES INDICATE LIGHT RAINFALL TO OCCUR DURING
THE MORNING ISENTROPIC LIFT. I WILL INCREASE POP WELL INTO THE CHC
RANGE ACROSS THE EAST FACING SLOPES AND ADJACENT FOOTHILLS...WITH
SCHC ELSEWHERE. THE LLVL LIFT APPEARS TO WEAKEN DURING THE AFTERNOON
HOURS...HOWEVER...WEAK SYNOPTIC SCALE FORCING INCREASES WITH THE
APPROACH OF A MID LEVEL TROF...SUPPORTING SCHC POPS EAST OF THE MTNS
WITH MTN CHC. GIVEN THE THICK CLOUD COVER...NE SFC WIND...AND
PERIODS OF -RA...FRI TEMPS MAY ONLY WARM 3 TO 5 DEGREES OVER VALUES
EXPECTED FOR TODAY.
FRIDAY NIGHT THROUGH SATURDAY NIGHT...SFC RIDGING ACROSS THE CWA
WILL GRADUALLY WEAKEN AND ISENTROPIC LIFT WILL DISSIPATE. FORECAST
SOUNDINGS INDICATE THAT LLVL CLOUD COVER WILL GRADUALLY THIN WITH
THE LOSS OF LIFT. HOWEVER...WINDS WILL LIKELY SHIFT TO THE
SOUTH-SOUTHWEST AS THE HIGH WEAKENS AND LOW PRESSURE DEVELOPS OVER
THE MID MISSISSIPPI VALLEY. LLVL THICKNESSES AND TEMPERATURE
PROFILES WILL REMAIN VERY MILD THROUGH THE PERIOD...SUPPORTING MIN
TEMPS SATURDAY AND SUNDAY AROUND 10 DEGREES ABOVE NORMAL. HIGHS ON
SATURDAY MAY RANGE FROM 10 TO 15 DEGREES ABOVE NORMAL...ESPECIALLY
IF CLOUDS BREAK. POPS WILL REMAIN LIMITED GIVEN THE LACK OF
FORCING...HOWEVER...SCT MTN -RA IS POSSIBLE UNDER BROAD MID LEVEL
CYCLONIC FLOW.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 230 AM THURSDAY...THE MEDIUM RANGE MODELS ARE IN GOOD
AGREEMENT ON THE PROGRESSION OF THE COLD FRONT AND EXPANSION OF HIGH
PRESSURE BEHIND THE FRONT IN MID WEEK. STARTING AT 12Z SUNDAY...
HIGH PRESSURE CENTERED GENERALLY NEAR BERMUDA WITH GOOD FETCH OF
SOUTHERLY FLOW AND SHORTWAVE PROGRESSING ACROSS NORTHERN PLAINS. A
BIT MORE FAVORABLE FOR CONVECTION IN THE NC MOUNTAINS AND BROUGHT
POPS UP TO VERY LOW CHANCE SUNDAY AFTERNOON NEAR LAKE TOXAWAY OVER
THE CULLOWHEE AREA. GFS CAPE FOR SUNDAY AFTERNOON IS QUITE LOW IN
THE 20 TO 40 JOULES AND ECMWF IS HIGHER IN THE 100 TO 300 RANGE.
THE FRONT IS WELL DEFINED LATE SUNDAY NIGHT AND MOVING EAST. THE GFS
CONTINUES TO BE SLIGHTLY MORE PROGRESSIVE IN MOVING THE FRONT EAST
ACROSS THE AREA WITH THE NEW ECMWF LAGGING THE PRECIP BACK...FROM
MID ALABAMA TO FAR EAST TENNESSEE AT 00Z TUESDAY. CAPES ARE RATHER
LOW AND WIND SHEAR CONTINUES TO BE UP FOR MONDAY AFTERNOON. GFS
CAPES MONDAY AFTERNOON BEST ALONG AND EAST OF I-77 WITH 100 TO 200
AND 850MB WIND AROUND 40KTS AND 700MB WIND 65KTS NEAR CHARLOTTE. NEW
ECMWF CAPES AROUND 200 JUST EAST OF CHARLOTTE MONDAY AFTERNOON. THE
CANADIAN MODEL HAS FRONTAL PRECIP STRAIGHT UP THE APPALACHIAN CHAIN
AT 00Z TUESDAY. AFTER USING GFS CAPE ONLY SHOWED A LITTLE THUNDER IN
THE CHARLOTTE AREA MONDAY AFTERNOON. AT THIS POINT...THAT SEEMS TO
BE THE PLACE TO WATCH BUT ALL COULD CHANGE AS THAT IS STILL DAY 5 OF
THE FORECAST.
AS THE FRONT MOVES EAST LATE MONDAY NIGHT INTO EARLY TUESDAY...VERY
BRIEF WRAP AROUND MOISTURE LINGERS IN THE NC MOUNTAINS. THAT ONLY
LASTS 3 TO 6 HOURS AND LONGEST ON THE ECMWF WHERE IT HANGS ON TO MID
DAY TUESDAY. SURFACE HIGH CENTERED OVER NC EARLY WEDNESDAY AS THE
NEXT SIGNIFICANT SHORTWAVE CROSSES TEXAS AND OKLAHOMA MOVING EAST.
THIS GENERATES A SIGNIFICANT GULF OF MEXICO LOW PRESSURE WEDNESDAY
NIGHT ON THE GFS AND MOVES IT NORTHEAST FROM MISS DELTA REGION. THE
ECMWF IS MUCH LESS ROBUST. THE GFS AND ECMWF HAS LIGHT PRECIP MOVING
UP OVER NE GA AND UPSTATE AT 12Z THURSDAY OF NEXT WEEK. KEPT POPS
BELOW SLIGHT AT THE END OF DAY 7 AND FUTURE SHIFTS WILL EVALUATE.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
AT KCLT...WINDS WILL BE OUT OF THE NE THROUGH THE VALID PERIOD OF
THE TAF. SPEEDS WILL INCREASE TO AROUND 10 KTS LATE TONIGHT. A CIG
UP AROUND 8KFT SHOULD MOVE IN FROM THE WEST HERE SHORTLY. SOME OF
THE MODELS HAVE MVFR CIGS DEVELOPING AROUND 12 UTC AS A SECONDARY
COLD FRONT COMES THROUGH. THE RUC BUFKIT SOUNDINGS EVEN IMPLY
SOMETHING ON THE BORDER WITH IFR. WHILE THE MOS ISN/T SHOWING
ANYTHING...THERE IS ENUF RAW MODEL OUTPUT WITH MVFR CIGS THAT I/VE
ADDED A 1700 FOOT CIG FROM 11-14 UTC. AFTER THAT THE CIGS SHOULD
RISE AGAIN.
ELSEWHERE...CLOUDS WILL BE MAINTAINED OVER A DOME OF COOL...DRY AIR
AT THE SURFACE. FOR THE REST OF THE NIGHT CIGS SHOULD STAY IN THE
VFR RANGE AT ALL TAF SITES. WINDS WILL BE OUT OF THE NE THROUGH THE
VALID PERIOD OF THE TAFS OVER THE FOOTHILLS AND PIEDMONT AND VERY
LIGHT OUT OF THE SE UP THE FRENCH BROAD VALLEY. CIGS ARE EXPECTED TO
LOWER INTO THE HIGH END OF THE MVFR RANGE BY MID TO LATE MORNING ON
THURSDAY. A FEW SPRINKLES OR LIGHT SHOWERS ARE POSSIBLE OVER THE
UPSTATE TONIGHT AND AT KAVL ON THURSDAY.
OUTLOOK...RESTRICTIVE CIGS ARE EXPECTED LATE THURSDAY NIGHT THROUGH
SATURDAY MORNING. THE REGION WILL MOVE INTO A WARM SECTOR AFTER THAT
WITH GENERALLY FAIR CONDITIONS LATER SATURDAY AND SUNDAY.
HOWEVER...PATCHY FOG AND STRATUS WILL BE POSSIBLE BOTH SUNDAY AND
MONDAY MORNINGS. A STRONG COLD FRONT WILL CROSS THE REGION ON
MONDAY...ACCOMPANIED BY SHOWERS AND THUNDERSTORMS ALONG WITH GUSTY
WINDS.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...MCAVOY
SHORT TERM...NED
LONG TERM...DEO
AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1242 AM EST THU DEC 6 2012
.SYNOPSIS...
A COLD FRONT WILL REACH THE SOUTH CAROLINA COAST THIS EVENING. HIGH
PRESSURE WILL RETURN OVER THE AREA FOR THURSDAY AND FRIDAY. EXPECT
THIS HIGH TO BECOME CENTERED OFF THE EAST COAST WHICH WILL RESULT IN
A STRONG SOUTHERLY FLOW OF WARM AND MOIST AIR OVER THE WEEKEND.
ANOTHER COLD FRONT WILL APPROACH THE REGION EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
AS OF 1240 AM EST THURSDAY...CLOUDS HAVE MOVED A LITTLE FARTHER
NORTH THAN EXPECTED AND THE SKY GRIDS HAVE BEEN UPDATED TO REFLECT
THIS. A FEW LIGHT SHOWERS ARE MOVING INTO NE GA...BUT I THINK THE
SLIGHT CHANCE POPS OUT THAT WAY WILL HANDLE THIS FOR NOW.
1000 PM UPDATE...SHOWERS HAVE DIMINISHED IN COVERAGE ACROSS THE SC
PIEDMONT DURING THE PAST COUPLE OF HOURS AS THE FRONT CONTINUES TO
PUSH SOUTH OF THE AREA. WEAK ISENTROPIC LIFT ASSOCIATED WITH COLD
AIR DAMMING OVERNIGHT WILL PRODUCE LOW LEVEL CLOUDS ACROSS MUCH OF
OUR CWA EXCEPT NORTHERN NC MOUNTAINS WHERE SOME CLEARING IS EXPECTED
AS DRY AIRMASS MOVES IN FROM THE NORTH.
AT 230 PM... FOR THE REMAINDER OF THE AFTERNOON... SHOWERS AND
POSSIBLY AN ISOLATED THUNDERSTORM OR TWO WILL ADVANCE ACROSS THE
PIEDMONT AS THE LEADING EDGE OF THE FRONTAL BOUNDARY SINKS SLOWLY
SOUTHWARD THROUGH THE SOUTH CAROLINA ZONES. RAP INDICATES SURFACE
DEWPOINTS CLOSE TO 60 DEGREES WILL POOL IN THE UPSTATE DUE TO
CONVERGENCE IN THE FRONTAL ZONE. THIS IS THE AREA WITH CAPES IN THE
150 TO 300 J/KG RANGE. THUS... ANY THUNDER THAT DOES OCCUR IS MOST
LIKELY ACROSS THE SOUTHERN PIEDMONT OF NORTH CAROLINA AND THE
UPSTATE OF SOUTH CAROLINA THROUGH EARLY EVENING. OTHERWISE... DRIER
AIR WILL SPREAD INTO THE NORTHERN ZONES AND PARTIAL CLEARING WILL
OCCUR THERE TONIGHT.
500 MB FLOW ACROSS THE CWA DURING THE NEAR TERM PART OF THE FORECAST
WILL BE PRIMARILY FROM THE WEST. THE TROUGH ALOFT MOVING ACROSS THE
GULF OF MEXICO TONIGHT AND THURSDAY WILL NOT BE A MAJOR PLAYER IN
OUR WEATHER. A STRONG SHORT WAVE TROUGH MOVING THROUGH NEW ENGLAND
AND EASTERN CANADA WILL BE THE MAIN FEATURE PUSHING THE COLD FRONT
SOUTH OF THE AREA THIS EVENING. SURFACE HIGH BEHIND THE FRONT WILL
BE OVER THE GREAT LAKES THIS EVENING MOVING TO A POSITION OVER THE
MID-ATLANTIC STATES AND NEW ENGLAND THURSDAY AFTERNOON. THE COLD AIR
DAMMING PATTERN THAT DEVELOPS WILL RESULT IN A NORTHEAST WIND AND
TEMPERATURES TOMORROW THAT ARE MUCH CLOSER TO NORMAL THAN THE
TEMPERATURES OF RECENT DAYS. BY THE END OF THE PERIOD... THE HIGH
CENTER IS ALREADY SHOWING SIGNS OF DRIFTING OFFSHORE... BUT THE
SOUTHWESTERN NOSE OF THE HIGH WILL CONTINUE TO EXTEND SOUTHWESTWARD
INT THE CWA DURING EARLY EVENING THURSDAY. THE FRONTAL ZONE TO OUR
SOUTH WILL NEVER QUITE CLEAR THE FAR WESTERN ZONES AND THE AIR MASS
CHANGE THERE WILL BE LESS NOTICEABLE THAN EAST OF THE MOUNTAINS.
QUITE A BIT OF FRONTAL ZONE MOISTURE WILL REMAIN OVER THE AREA...
BUT NORTHERN ZONES WILL HAVE A PERIOD OF NEARLY CLOUD FREE SKIES
BEFORE CLOUDS RETURN DURING THURSDAY AS ISENTROPIC LIFT DEVELOPS
OVER THE SOUTHWESTERN PERIPHERY OF THE OFFHSORE HIGH.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY/...
AS OF 145 PM WEDNESDAY...SFC RIDGING...NOSED SSWWD INTO THE CWFA...
WILL LINGER THRU THURSDAY NIGHT. FORCING FOR ANY PCPN WILL BE IN THE
FORM OF WEAK UPGLIDE/UPSLOPE...RESULTING IN SCATTERED LIGHT
RAIN/SHOWER/DRIZZLE POSSIBILITIES...MAINLY ACRS THE MTNS/FTHLS.
MOUNTAIN MIN TEMPS SHOULD EXPERIENCE A NEGATIVE VALLEY TO RIDGETOP
LAPSE RATE...AND AT THIS JUNCTURE...WE ARE EXPECTING EVEN THE
COLDEST NC MTN VALLEYS TO REMAIN JUST ABOVE FREEZING. LLVL WAA FLOW
REGIME IS PROGGED TO LINGER ATOP WEAKENING SFC RIDGE ON FRIDAY.
SHORT RANGE MODELS CONTINUE TO ADVERTISE SPOTTY RESPONSE AND WOULD
EXPECT THE PROSPECT FOR ANYTHING MORE THAN FILTERED OR DIM SUNSHINE
DEVELOPMENT TO BE LOW. NONETHELESS...TEMPERATURES SHOULD MODERATE
SOME FROM THURSDAY/S CHILLY READINGS...WITH A MOS BLEND SUPPORTING
ABOUT A 5 DEG F BUMP. A DEEPER/QUICKENING WSW FLOW WILL DEVELOP ATOP
THE SE CONUS ON SATURDAY ERODING THE LINGERING COOL WEDGE AND
CONTRIBUTING TO TEMPERATURES WARMING TO 10 DEG F ABOVE CLIMO. A
FRONTAL BNDRY IS PROGGED TO MAKE A PUSH TOWARD THE MTNS LATE IN THE
DAY BUT SHOULD STALL WELL NW OF THE AREA. PLUME OF WEAK INSTABILITY
AHEAD OF THIS FEATURE COMBINED WITH TERRAIN LIFT COULD BE ENOUGH TO
TRIGGER A FEW MTN SHOWERS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 230 PM WEDNESDAY...MODELS HAVE CONVERGED ON THE TIMING OF A
COLD FROPA ON MONDAY...AS A LOW PRES SYSTEM TRACKS FROM THE SOUTHERN
PLAINS TO THE GREAT LAKES OVER THE WEEKEND. BEFORE THE FRONT
ARRIVES...PERSISTENT DEEP SWLY FLOW WILL CONTINUE ACRS THE FA. MOS
SEEMS OVERDONE ON POPS THRU SUNDAY NIGHT...AS THE ONLY FORCING FOR
PRECIP WILL BE UPSLOPE IN THE SW NC MTNS. I AM UNDERCUTTING THE
GUIDANCE ON POPS SATURDAY NIGHT THRU SUNDAY NIGHT.
THE LATEST MODEL CONSENSUS HAS THE FRONT CROSSING THE CWFA FROM WEST
TO EAST DURING THE DAY ON MONDAY. A FAIRLY GOOD MOISTURE PLUME WILL
ACCOMPANY THE FRONT WITH STRONG UPPER LEVEL DIVERGENCE. SO POPS ARE
RAMPED UP TO LIKELY IN THE MTNS AND HIGH-END CHC EAST. THIS WOULD BE
A MORE FAVORABLE TIME OF DAY FOR INSTBY. WITH THAT SAID...THE MODELS
ARE STILL MEAGER ON SBCAPE...WITH THE GFS AND ECMWF HAVING 100-200
J/KG AHEAD OF THE FRONT. SHEAR DOES LOOK GOOD THO...WITH SWLY 0-6KM
BULK SHEAR 50-60 KTS IN THE PIEDMONT AND EVEN GREATER TO THE WEST.
THE GFS FCST SNDG SHOWS SOME DIRECTIONAL SHEAR AS WELL WITH 0-3KM
HELICITY IN THE 150-250 M2/S2 RANGE. SO EVEN A LITTLE INSTBY COULD
BE ENUF FOR A HIGH-SHEAR/LOW-CAPE SEVERE EVENT. USING THE GFS CAPE
AS A GUIDE...DID ADD SOME MENTION OF THUNDER FOR MONDAY.
MONDAY NIGHT INTO TUESDAY...AS THE LOW WRAPS UP OVR THE EASTERN
GREAT LAKES...NWLY LLVL FLOW WILL USHER IN COLD AIR ACRS THE AREA.
GUIDANCE SEEMS TO INDICATE THAT THE COLD AIR WILL CHASE THE
MOISTURE...SUCH THAT VERY LITTLE IF ANY SNOW WILL FOLLOW BEHIND THE
FROPA. I GRADUALLY RAMP POPS DOWN INTO TUESDAY...WITH SNOW LEVELS
POSSIBLY FALLING TO 3500 FT BEFORE DAYBREAK TUESDAY. NO SIGNIFICANT
ACCUMS ARE EXPECTED. TUESDAY WILL BE COOLER WITH TEMPS NEAR OR
SLIGHTLY BELOW NORMAL. DRY HIGH PRES BUILDS IN FOR WEDNESDAY.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
AT KCLT...WINDS WILL BE OUT OF THE NE THROUGH THE VALID PERIOD OF
THE TAF. SPEEDS WILL INCREASE TO AROUND 10 KTS LATE TONIGHT. A CIG
UP AROUND 8KFT SHOULD MOVE IN FROM THE WEST HERE SHORTLY. SOME OF
THE MODELS HAVE MVFR CIGS DEVELOPING AROUND 12 UTC AS A SECONDARY
COLD FRONT COMES THROUGH. THE RUC BUFKIT SOUNDINGS EVEN IMPLY
SOMETHING ON THE BORDER WITH IFR. WHILE THE MOS ISN/T SHOWING
ANYTHING...THERE IS ENUF RAW MODEL OUTPUT WITH MVFR CIGS THAT I/VE
ADDED A 1700 FOOT CIG FROM 11-14 UTC. AFTER THAT THE CIGS SHOULD
RISE AGAIN.
ELSEWHERE...CLOUDS WILL BE MAINTAINED OVER A DOME OF COOL...DRY AIR
AT THE SURFACE. FOR THE REST OF THE NIGHT CIGS SHOULD STAY IN THE
VFR RANGE AT ALL TAF SITES. WINDS WILL BE OUT OF THE NE THROUGH THE
VALID PERIOD OF THE TAFS OVER THE FOOTHILLS AND PIEDMONT AND VERY
LIGHT OUT OF THE SE UP THE FRENCH BROAD VALLEY. CIGS ARE EXPECTED TO
LOWER INTO THE HIGH END OF THE MVFR RANGE BY MID TO LATE MORNING ON
THURSDAY. A FEW SPRINKLES OR LIGHT SHOWERS ARE POSSIBLE OVER THE
UPSTATE TONIGHT AND AT KAVL ON THURSDAY.
OUTLOOK...RESTRICTIVE CIGS ARE EXPECTED LATE THURSDAY NIGHT THROUGH
SATURDAY MORNING. THE REGION WILL MOVE INTO A WARM SECTOR AFTER THAT
WITH GENERALLY FAIR CONDITIONS LATER SATURDAY AND SUNDAY.
HOWEVER...PATCHY FOG AND STRATUS WILL BE POSSIBLE BOTH SUNDAY AND
MONDAY MORNINGS. A STRONG COLD FRONT WILL CROSS THE REGION ON
MONDAY...ACCOMPANIED BY SHOWERS AND THUNDERSTORMS ALONG WITH GUSTY
WINDS.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...MCAVOY
SHORT TERM...CSH
LONG TERM...ARK
AVIATION...MCAVOY
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
805 PM CST FRI DEC 7 2012
.DISCUSSION...
ACTIVE FORECAST IN THE SHORT TERM. WENT AHEAD AND ALLOWED THE WINTER
WEATHER ADVISORY EXPIRE ACROSS THE AREA WITH ONLY MINOR ADDITIONAL
ACCUMULATIONS EXPECTED THROUGH THE EVENING. ATMOSPHERE IS EXPECTED
TO GRADUALLY DRY FROM ALOFT RESULTING IN DENDRITIC LAYER BEING CUT
OFF BRINGING AN END TO THE SNOW. LOW LEVEL SATURATION IS EXPECTED TO
REMAIN ACROSS THE AREA AND FOG HAS STARTED TO DEVELOP IN THE
STAGNANT AIR IN CENTRAL SOUTH DAKOTA. ADDED PATCHY FOG THIS EVENING
ACROSS THE WESTERN CWA THIS EVENING...BUT AS SOUTHERLY FLOW STARTS
TO INCREASE EARLY SATURDAY MORNING...THIS MAY LIMIT THE AREAL
COVERAGE WEST OF THE JAMES. FURTHER TO THE EAST...MUCH GREATER
POTENTIAL FOR FOG AS STRATUS BUILDS DOWN FROM ALOFT IN LIGHT
EASTERLY FLOW. RAP HAS DEVELOPED FAIRLY LARGE AREA ALONG AND EAST OF
I-29 OF FOG...AND MAY HAVE TO INCREASE WORDING AND NIGHT CREW MAY
NEED TO CONSIDER DENSE FOG ADVISORY. UPDATE POSTED.
&&
.AVIATION.../FOR THE 00Z TAF ISSUANCE/
WIDESPREAD IFR TO MVFR CEILINGS AND VISIBILITIES WILL PERSIST ACROSS
THE REGION THROUGH 00Z SUNDAY. LIGHT SNOW MAINLY ALONG AND EAST OF
I29 WILL GRADUALLY END DURING THE NIGHT...WITH ANOTHER ROUND OF SNOW
SPREADING IN FROM THE WEST AFTER 18Z SATURDAY.
&&
.PREV DISCUSSION.../ISSUED AT 333 PM CST/
SHORT WAVE ENERGY...WELL DELINEATED BY THE MID AND UPPER QG FORCING
MOVING ACROSS OUR NORTHERN ZONES...WILL EXIT OUR FORECAST AREA THIS
EVENING. LIGHT SNOW WILL LINGER THIS EVENING THROUGHOUT OUR EASTERN
ZONES AS THIS WAVE EXISTS. HOWEVER THE MESOSCALE DYNAMICS HAVE
LARGELY DISSIPATED. THEREFORE ONLY BROAD LIFT REMAINS...AND AN
ATMOSPHERE WHICH IS DRYING OUT ALOFT. THE WILD CARD TONIGHT IS CLOUD
COVER. MODEL HUMIDITY TIME SECTIONS STRONGLY SUGGEST THAT STRATUS
WILL LINGER IN OUR FORECAST AREA. AND IN AREAS WHERE IT WOULD HAPPEN
TO CLEAR OUT SOMEWHAT THIS EVENING...THE STRATUS IS LIKELY TO OOZE
BACK DOWN FROM THE NORTH. THEREFORE KEPT SKY COVER EITHER CLOUDY OR
MOSTLY CLOUDY WHICH SHOULD HOLD THE LOWS UP RELATIVELY SPEAKING. IF
PARTS OF THE FORECAST AREA WOULD HAPPEN TO CLEAR OUT...THEN LOWS
WILL CERTAINLY BE COLDER THAN FORECAST...ESPECIALLY OVER AREAS OF
NEW SNOW COVER. SOMETHING TO WATCH FOR. /MJF
RELATIVELY CONSISTENT FORECAST FROM THE MODELS FOR TOMORROW LEADS TO
SLIGHTLY ABOVE NORMAL CONFIDENCE. A WARM FRONT IN THE 800-650MB
LAYER WILL MOVE INTO THE AREA LATE SATURDAY MORNING...THEN MOVE INTO
THE EASTERN CWA BY TOMORROW EVENING. WHILE INSTABILITY IS NOT
IMPRESSIVE...THERE APPEARS TO BE ENOUGH TO SUPPORT A RELATIVELY FAST
MOVING BAND OF SNOWFALL DEVELOPMENT AS IT PASSES. EXPECT ABOUT AN
INCH OF POTENTIAL AS IT PASSES. WARMER AIR WILL SURGE NORTHWARD
DURING THE DAY AS LOW PRESSURE WRAPS UP TO THE NORTH AND WEST SO
WILL AIM FOR NEAR 40 ALONG THE MISSOURI RIVER VALLEY WITH LOWER 30S
IN THE FAR NORTHERN CWA. WITH THIS WARMER AIR SOME LIGHT RAIN WILL
BE POSSIBLE IN PARTS OF NORTHWEST IOWA BUT OVERALL THE MODELS ARE A
LITTLE COLDER THAN YESTERDAY WHICH SUPPORTS MORE SNOW VERSUS RAIN.
SATURDAY NIGHT INTO SUNDAY WILL SEE AN ARCTIC AIR MASS SURGE SOUTH
BEHIND THE EXITING LOW PRESSURE. UPPER LEVEL SUPPORT AS WELL AS A
LITTLE WEAK THETA E ADVECTION AND MID LEVEL FRONTAL FORCING WILL
ALLOW FOR THE CONTINUED THREAT FOR LIGHT SNOW SATURDAY NIGHT INTO
SUNDAY MORNING...MAINLY IN THE EASTERN CWA. AMOUNTS WILL BE LIMITED
SO NOT EXPECTING ANY HEADLINES AT THIS TIME. THE ONLY HEADLINER
POTENTIAL WILL BE WIND ADVISORY AS A STRONG PRESSURE GRADIENT AND 40
KNOT 925MB WIND COMBINE TO BRING THE POTENTIAL FOR 30 TO 40 MPH
WINDS ON SUNDAY. WHEN COMBINED WITH THE VERY COLD TEMPERATURES WIND
CHILLS OF ZERO TO TEN BELOW WILL BE LIKELY.
CLEARING SKIES AND A WEAK SHORT LIVED RIDGE OF HIGH PRESSURE WILL
MOVE THROUGH ON SUNDAY NIGHT...WITH SOUTHERLY FLOW DEVELOPING DURING
THE DAY MONDAY. LOWS AROUND ZERO MUCH OF THE AREA WITH 5 TO 10
ABOVE IN LOCATIONS WITH LITTLE OR NO SNOW COVER. HIGHS ON MONDAY
WILL MAINLY BE IN THE 20S SO A LITTLE BIT IN THE COLD SIDE.
IN THE LATTER PERIODS(TUE/FRI)...WEST NORTHWEST FLOW ALOFT WILL
GRADUALLY TRANSITION TO SOUTHWEST FLOW ALOFT. THIS WILL KEEP
TEMPERATURES AT OR BELOW NORMAL THROUGH THE PERIOD WITH LITTLE IN
THE WAY OF PRECIPITATION CHANCES. AT THIS TIME IT APPEARS THAT A JET
STREAK WILL MOVE THROUGH THE REGION BRINGING A SLIGHT WARM UP
TUESDAY INTO WEDNESDAY THEN COLDER AIR WILL AGAIN FILTER SOUTHWARD.
GENERALLY HIGHS IN THE 30S TUESDAY AND WEDNESDAY...A FEW 40S SOUTH
ON WEDNESDAY...THEN BACK INTO THE 20S THURSDAY AND FRIDAY.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
MN...NONE.
NE...NONE.
SD...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1219 PM CST THU DEC 6 2012
.AVIATION...
CONCERNS INCLUDE IFR/MVFR TRENDS WITH CIGS/VSBYS AFTER MIDNIGHT
INTO FRIDAY MORNING.
MORNING FG/BR AND CIGS RETREATING BACK EAST ONCE AGAIN AS WARM AIR
ABOVE THE INVERSION AND WITHIN THE EML IS NOW MIXING DOWN. SOUTH
WINDS 10-15 KTS WILL BE THE RULE...THOUGH WILL SETTLE DOWN
AT/BELOW 10 KTS OVERNIGHT.
VFR THROUGH MIDNIGHT. AFTERWARD...MOIST BOUNDARY LAYER AND MODEST
30-40 KT LLJ SHOULD RESULT IN MAINLY STRATUS...THOUGH WHERE WINDS
DROP OFF...SOME OCCASIONAL VSBY FALLS INTO MVFR OR IFR CATEGORIES
WILL BE POSSIBLE. SIMILAR TIMING IS EXPECTED FRIDAY WITH CLOUDS/PATCHY
FOG DISPERSING BEFORE MIDDAY. MADE ONLY MINOR TWEAKS TO THE PREVIOUS
FORECAST AFTER MIDNIGHT TONIGHT.
05/
&&
.UPDATE...
NO UPDATE PLANNED.
CURRENT FORECAST THROUGH SATURDAY IS ON TRACK. THE FOG HAS ENDED
FOR THE DAY. CLOUDY SKIES OVER THE EASTERN CWA WILL BREAK APART
DURING THE AFTERNOON AND ALLOW TEMPERATURES TO WARM TO FORECAST
HIGHS. STILL EXPECT SOME FOG REDEVELOPMENT LATE TONIGHT THROUGH MID
FRIDAY MORNING.
A STRONG COLD FRONT IS EXPECTED TO PUSH THROUGH THE CWA ON SUNDAY.
THERE WILL BE AN OPPORTUNITY FOR RAIN AND THUNDERSTORMS SUNDAY
MORNING THROUGH EVENING ALONG AND AHEAD OF THE FRONT. THE AIR MASS
BEHIND THIS FRONT IS FROM NORTHWEST AND WESTERN CANADIAN WITH
SOME NORTHEAST PACIFIC AIR MERGING WITH IT. IT WILL BE MUCH
COLDER ON MONDAY WITH A GOOD FREEZE EXPECTED ON TUESDAY MORNING.
NEW MODELS HAVE ROLLED IN AND WILL RE-EVALUATE THE POTENTIAL FOR
MORE OR LESS RAINFALL AND COLDER TEMPERATURES AREAWIDE... AND ALSO
THE POTENTIAL FOR BRIEF WINTER WEATHER OVER THE NORTHWEST
COUNTIES ON LATE SUNDAY NIGHT. 75
&&
.PREV DISCUSSION... /ISSUED 356 AM CST THU DEC 6 2012/
WARM AIR ADVECTION ACROSS THE REGION THIS MORNING IS BRINGING
INCREASING DEWPOINTS...LOW STRATUS...AND FOG TO A GOOD PORTION OF
NORTH AND CENTRAL TEXAS. VISIBILITIES WITHIN FOGGY AREAS HAVE
VARIED THROUGH THE NIGHT BUT SEVERAL SITES HAVE REPORTED DENSE
FOG. HOWEVER...SOME SITES THAT PREVIOUSLY REPORTED DENSE FOG HAVE
NOW IMPROVED VISIBILITIES. THE CURRENT DENSE FOG ADVISORY THAT IS
IN EFFECT FOR THE SOUTHEASTERN COUNTIES WILL REMAIN AS IS FOR NOW
BUT ADJUSTMENTS TO THE AREA MAY BE NEEDED BEFORE THE 10 AM
EXPIRATION.
MOST GUIDANCE TONIGHT IS HAVING A HARD TIME WITH THE CLOUDS BUT
THE RAP MODEL AND LAMP MOS GUIDANCE HAVE RECENTLY PICKED UP ON THE
TRENDS. HOWEVER...BOTH OF THESE MODELS SCATTER THE CLOUDS OUT BY
MIDDAY. THE 00Z RUN OF THE 4 KM WRF IS THE ONLY MODEL HOLDING THE
CLOUDS IN OVER THE EASTERN HALF OF THE REGION FOR MUCH OF THE DAY.
WITH DEEP SOUTHERLY FLOW CONTINUING TODAY... WILL SIDE WITH THE
00Z 4 KM WRF AND KEEP MOSTLY CLOUDY CONDITIONS OVER THE EASTERN
HALF OF THE REGION THROUGH MID AFTERNOON. DUE TO THE CLOUD
COVER...HAVE LOWERED HIGH TEMPERATURES OVER THE EASTERN HALF INTO
THE 60S TODAY. THE LATEST RUNS OF THE RAP MODEL ARE ALSO SHOWING
COOL TEMPERATURES OVER THE EASTERN COUNTIES THIS AFTERNOON...BUT
FELT THE RAP/S TEMPERATURES WERE TOO LOW.
STRATUS WILL RETURN AGAIN TONIGHT AND SOME PATCHY FOG WILL ALSO BE
POSSIBLE...MAINLY OVER THE SOUTHEASTERN COUNTIES. THE WINDS
TONIGHT WILL BE SLIGHTLY STRONGER AS A SURFACE LOW MOVES CLOSER
FROM THE NORTHWEST. THEREFORE THE CHANCES FOR DENSE FOG AND/OR
WIDESPREAD FOG ARE LOWER. WITH THE STRONGER WINDS...STRATUS IS
MORE LIKELY BUT WILL CONTINUE TO ASSESS THE FOG POTENTIAL AND
ESPECIALLY THE WIND SPEEDS FOR TONIGHT.
A COLD FRONT THAT IS CURRENTLY MOVING DOWN THE PLAINS AND INTO
NEBRASKA THIS MORNING WILL SLIDE INTO NORTH TEXAS LATE TONIGHT.
THIS FRONT WILL STALL ACROSS THE NORTHWESTERN COUNTIES ON FRIDAY
AND THEN RETREAT NORTH ON SATURDAY AS A STRONG UPPER LEVEL
TROUGH DIVES DOWN THE ROCKIES AND INDUCES LEE-SIDE CYCLOGENESIS.
THE GFS CONTINUES TO BE AGGRESSIVE WITH PUSHING THE FRONT DEEPER
IN OUR AREA THAN THE OTHER MODELS SUGGEST. CURRENT TEMPERATURES
BEHIND THE FRONT ARE IN THE 40S AND THIS AIR WILL CONTINUE TO
MODIFY AS THE FRONT MOVES FARTHER SOUTH. DUE TO THE MODIFIED
NATURE OF THE AIR AND THE ZONAL UPPER LEVEL FLOW PATTERN...DO NOT
THINK THE FRONT WILL MAKE IT MUCH FARTHER THAN THE NORTHWESTERN
COUNTIES.
MOISTURE ADVECTION WILL CONTINUE AHEAD OF THIS FIRST FRONT ON
FRIDAY AND SATURDAY. DEWPOINTS WILL EVENTUALLY REACH THE 60S BY
SATURDAY AND THUS OVERNIGHT LOWS WILL ALSO QUICKLY WARM THIS
WEEKEND. A WEAK ELONGATED SHORTWAVE WILL MOVE OVER THE REGION
FRIDAY NIGHT/SATURDAY MORNING. FORECAST MODELS INDICATE THE LOW
LEVEL MOISTURE DEPTH WILL HAVE INCREASED TO BETWEEN 5-8 KFT BY
THEN AND THE CAP WILL BE WEAKENED ENOUGH FOR SOME AREAS OF LIGHT
RAIN OR SHOWERS TO DEVELOP OVER ROUGHLY THE EASTERN HALF OF THE
REGION. HAVE INTRODUCED 20 POPS FRIDAY NIGHT THROUGH SATURDAY
MORNING ANTICIPATING SCATTERED LIGHT RAIN ACTIVITY OR LIGHT
SHOWERS.
ON SUNDAY...THE UPPER LEVEL TROUGH THAT WAS PREVIOUSLY MENTIONED
OVER THE ROCKIES WILL SWING INTO THE SOUTHERN PLAINS...SENDING A
STRONG CANADIAN COLD FRONT ACROSS THE REGION. THE ECMWF CONTINUES
TO BE THE SLOWEST WITH THE FRONT AND UPPER LEVEL TROUGH WHILE THE
GFS AND NAM ARE THE FASTEST. BOTH THE GFS AND ECMWF HAVE SHOWN
GOOD RUN-TO-RUN CONSISTENCY WITH THEIR RESPECTIVE TIMINGS...THUS
IT IS DIFFICULT TO DETERMINE WHICH ONE IS MORE ACCURATE. BUT
EITHER WAY THE FRONT WILL ARRIVE ON SUNDAY AND OPTED TO SLOW THE
ARRIVAL OF THE FRONT BACK A FEW HOURS. THE EXACT TIMING OF THE
FRONT WILL HAVE MORE OF AN IMPACT ON HIGH TEMPS FOR THE DAY THAN
ANY OTHER PART OF THE FORECAST. THE MOISTURE PROFILES STILL LOOK
PRETTY MEAGER ALONG AND AHEAD OF THE FRONT AND KEPT LOW POPS
ACROSS THE REGION...BUT DID INCREASE POPS TO 40 PERCENT IN THE
SOUTHEAST WHERE THE MOISTURE PROFILES LOOK THE BEST. PRECIPITATION
SHOULD QUICKLY END SUNDAY NIGHT BUT NOW THE ECMWF IS SUGGESTING
SOME LIGHT SNOW MIGHT BE POSSIBLE OVER THE NORTHERN COUNTIES
SUNDAY NIGHT. THE ECMWF TEMPERATURE PROFILE IS MUCH COLDER TONIGHT
THAT LAST NIGHT/S RUN AND THIS WILL BE SOMETHING THAT NEEDS TO BE
CLOSELY WATCHED. PREVIOUSLY...FORECAST SOUNDINGS SHOWED THE
ATMOSPHERE QUICKLY DRYING OUT BEHIND THE FRONT...BUT NOW THE GFS
IS SHOWING A LITTLE INCREASE IN MID AND LOW LEVEL MOISTURE SUNDAY
NIGHT. WILL NOT MENTION ANY WINTER PRECIPITATION AT THIS TIME AND
CONTINUE TO ASSESS WITH UPCOMING MODEL RUNS. TEMPERATURES ON
MONDAY WILL REACH THE 40S BUT SOME LOCATIONS NEAR THE RED RIVER
WILL STRUGGLE TO GET INTO THE 40S. MONDAY NIGHT WILL BE A COLD
NIGHT WITH OVERNIGHT LOWS IN THE 20S ACROSS THE REGION.
THE CANADIAN FRONT WILL PUSH DEEP INTO THE GULF OF MEXICO AND THE
UPPER LEVEL TROUGH WILL SWING TO THE EAST COAST BY TUESDAY. ALL
THE MODELS HAVE ANOTHER PIECE OF UPPER LEVEL ENERGY DIVING DOWN
THE ROCKIES AND INTO THE PLAINS BY THE MIDDLE OF NEXT
WEEK...HOWEVER THEIR TRACKS AND TIMING OF THIS SECOND PIECE OF
ENERGY DIFFER CONSIDERABLY. THE GFS IS QUICK TO RETURN MOISTURE
BACK TO THE REGION AHEAD OF THE NEXT TROUGH AND BRINGS ABUNDANT
RAINFALL TO PARTS OF THE REGION. WITH SUNDAYS FRONT PUSHING DEEP
ACROSS THE GULF OF MEXICO...THIS SHOULD PREVENT ANY CHANCE OF LOW
LEVEL MOISTURE QUICKLY RETURNING TO NORTH AND CENTRAL TEXAS AND
WILL KEEP THE FORECAST DRY THROUGH THE END OF THE PERIOD.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 74 52 71 57 76 / 0 5 10 10 10
WACO, TX 74 52 74 60 79 / 0 5 10 10 10
PARIS, TX 65 50 70 56 72 / 0 5 10 10 10
DENTON, TX 73 49 70 53 75 / 0 5 10 10 10
MCKINNEY, TX 70 50 70 56 74 / 0 5 10 10 10
DALLAS, TX 73 54 71 58 77 / 0 5 10 10 10
TERRELL, TX 67 52 70 58 75 / 0 5 10 10 10
CORSICANA, TX 68 54 73 60 77 / 0 5 10 10 10
TEMPLE, TX 74 53 74 61 78 / 0 5 10 10 10
MINERAL WELLS, TX 77 47 70 52 78 / 0 5 10 10 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
05/75
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1143 AM CST THU DEC 6 2012
.UPDATE...
NO UPDATE PLANNED.
CURRENT FORECAST THROUGH SATURDAY IS ON TRACK. THE FOG HAS ENDED
FOR THE DAY. CLOUDY SKIES OVER THE EASTERN CWA WILL BREAK APART
DURING THE AFTERNOON AND ALLOW TEMPERATURES TO WARM TO FORECAST
HIGHS. STILL EXPECT SOME FOG REDEVELOPMENT LATE TONIGHT THROUGH MID
FRIDAY MORNING.
A STRONG COLD FRONT IS EXPECTED TO PUSH THROUGH THE CWA ON SUNDAY.
THERE WILL BE AN OPPORTUNITY FOR RAIN AND THUNDERSTORMS SUNDAY
MORNING THROUGH EVENING ALONG AND AHEAD OF THE FRONT. THE AIR MASS
BEHIND THIS FRONT IS FROM NORTHWEST AND WESTERN CANADIAN WITH
SOME NORTHEAST PACIFIC AIR MERGING WITH IT. IT WILL BE MUCH
COLDER ON MONDAY WITH A GOOD FREEZE EXPECTED ON TUESDAY MORNING.
NEW MODELS HAVE ROLLED IN AND WILL RE-EVALUATE THE POTENTIAL FOR
MORE OR LESS RAINFALL AND COLDER TEMPERATURES AREAWIDE... AND ALSO
THE POTENTIAL FOR BRIEF WINTER WEATHER OVER THE NORTHWEST
COUNTIES ON LATE SUNDAY NIGHT. 75
&&
.AVIATION...
CIGS AROUND 300 FEET WILL PREVAIL THROUGH THE EARLY MORNING HOURS
BUT SHOULD SLOWLY LIFT TO THE IFR CATEGORY BY/AROUND 16Z/10AM.
VSBY WILL GENERALLY BE NEAR 3-5SM THROUGH 15Z...BUT LOWER VSBY IS
POSSIBLE EARLY THIS MORNING. THE INVERSION SHOULD BREAK AROUND 17Z
TO 18Z AND THE IFR CIGS SHOULD SCATTER QUICKLY AROUND THIS TIME.
VFR WILL PREVAIL THIS AFTERNOON AND EVENING...BUT ANOTHER ROUND OF
CIGS LOOKS PROBABLE LATE TONIGHT. WILL SHOW MVFR CIGS MOVING INTO
TAF SITES AROUND 9Z. THESE CLOUDS MAY BE LOWER IF THE NAM
VERIFIES...BUT SINCE MOISTURE ADVECTION IS WEAKER TONIGHT AND
BOUNDARY LAYER WILL BE WARMER...THEY WILL LIKELY BE HIGHER BASED
THAN THIS MORNING. OTHERWISE SOUTH WINDS WILL PREVAIL AT 10-15 KT
TODAY. TR.92
&&
.PREV DISCUSSION... /ISSUED 356 AM CST THU DEC 6 2012/
WARM AIR ADVECTION ACROSS THE REGION THIS MORNING IS BRINGING
INCREASING DEWPOINTS...LOW STRATUS...AND FOG TO A GOOD PORTION OF
NORTH AND CENTRAL TEXAS. VISIBILITIES WITHIN FOGGY AREAS HAVE
VARIED THROUGH THE NIGHT BUT SEVERAL SITES HAVE REPORTED DENSE
FOG. HOWEVER...SOME SITES THAT PREVIOUSLY REPORTED DENSE FOG HAVE
NOW IMPROVED VISIBILITIES. THE CURRENT DENSE FOG ADVISORY THAT IS
IN EFFECT FOR THE SOUTHEASTERN COUNTIES WILL REMAIN AS IS FOR NOW
BUT ADJUSTMENTS TO THE AREA MAY BE NEEDED BEFORE THE 10 AM
EXPIRATION.
MOST GUIDANCE TONIGHT IS HAVING A HARD TIME WITH THE CLOUDS BUT
THE RAP MODEL AND LAMP MOS GUIDANCE HAVE RECENTLY PICKED UP ON THE
TRENDS. HOWEVER...BOTH OF THESE MODELS SCATTER THE CLOUDS OUT BY
MIDDAY. THE 00Z RUN OF THE 4 KM WRF IS THE ONLY MODEL HOLDING THE
CLOUDS IN OVER THE EASTERN HALF OF THE REGION FOR MUCH OF THE DAY.
WITH DEEP SOUTHERLY FLOW CONTINUING TODAY... WILL SIDE WITH THE
00Z 4 KM WRF AND KEEP MOSTLY CLOUDY CONDITIONS OVER THE EASTERN
HALF OF THE REGION THROUGH MID AFTERNOON. DUE TO THE CLOUD
COVER...HAVE LOWERED HIGH TEMPERATURES OVER THE EASTERN HALF INTO
THE 60S TODAY. THE LATEST RUNS OF THE RAP MODEL ARE ALSO SHOWING
COOL TEMPERATURES OVER THE EASTERN COUNTIES THIS AFTERNOON...BUT
FELT THE RAP/S TEMPERATURES WERE TOO LOW.
STRATUS WILL RETURN AGAIN TONIGHT AND SOME PATCHY FOG WILL ALSO BE
POSSIBLE...MAINLY OVER THE SOUTHEASTERN COUNTIES. THE WINDS
TONIGHT WILL BE SLIGHTLY STRONGER AS A SURFACE LOW MOVES CLOSER
FROM THE NORTHWEST. THEREFORE THE CHANCES FOR DENSE FOG AND/OR
WIDESPREAD FOG ARE LOWER. WITH THE STRONGER WINDS...STRATUS IS
MORE LIKELY BUT WILL CONTINUE TO ASSESS THE FOG POTENTIAL AND
ESPECIALLY THE WIND SPEEDS FOR TONIGHT.
A COLD FRONT THAT IS CURRENTLY MOVING DOWN THE PLAINS AND INTO
NEBRASKA THIS MORNING WILL SLIDE INTO NORTH TEXAS LATE TONIGHT.
THIS FRONT WILL STALL ACROSS THE NORTHWESTERN COUNTIES ON FRIDAY
AND THEN RETREAT NORTH ON SATURDAY AS A STRONG UPPER LEVEL
TROUGH DIVES DOWN THE ROCKIES AND INDUCES LEE-SIDE CYCLOGENESIS.
THE GFS CONTINUES TO BE AGGRESSIVE WITH PUSHING THE FRONT DEEPER
IN OUR AREA THAN THE OTHER MODELS SUGGEST. CURRENT TEMPERATURES
BEHIND THE FRONT ARE IN THE 40S AND THIS AIR WILL CONTINUE TO
MODIFY AS THE FRONT MOVES FARTHER SOUTH. DUE TO THE MODIFIED
NATURE OF THE AIR AND THE ZONAL UPPER LEVEL FLOW PATTERN...DO NOT
THINK THE FRONT WILL MAKE IT MUCH FARTHER THAN THE NORTHWESTERN
COUNTIES.
MOISTURE ADVECTION WILL CONTINUE AHEAD OF THIS FIRST FRONT ON
FRIDAY AND SATURDAY. DEWPOINTS WILL EVENTUALLY REACH THE 60S BY
SATURDAY AND THUS OVERNIGHT LOWS WILL ALSO QUICKLY WARM THIS
WEEKEND. A WEAK ELONGATED SHORTWAVE WILL MOVE OVER THE REGION
FRIDAY NIGHT/SATURDAY MORNING. FORECAST MODELS INDICATE THE LOW
LEVEL MOISTURE DEPTH WILL HAVE INCREASED TO BETWEEN 5-8 KFT BY
THEN AND THE CAP WILL BE WEAKENED ENOUGH FOR SOME AREAS OF LIGHT
RAIN OR SHOWERS TO DEVELOP OVER ROUGHLY THE EASTERN HALF OF THE
REGION. HAVE INTRODUCED 20 POPS FRIDAY NIGHT THROUGH SATURDAY
MORNING ANTICIPATING SCATTERED LIGHT RAIN ACTIVITY OR LIGHT
SHOWERS.
ON SUNDAY...THE UPPER LEVEL TROUGH THAT WAS PREVIOUSLY MENTIONED
OVER THE ROCKIES WILL SWING INTO THE SOUTHERN PLAINS...SENDING A
STRONG CANADIAN COLD FRONT ACROSS THE REGION. THE ECMWF CONTINUES
TO BE THE SLOWEST WITH THE FRONT AND UPPER LEVEL TROUGH WHILE THE
GFS AND NAM ARE THE FASTEST. BOTH THE GFS AND ECMWF HAVE SHOWN
GOOD RUN-TO-RUN CONSISTENCY WITH THEIR RESPECTIVE TIMINGS...THUS
IT IS DIFFICULT TO DETERMINE WHICH ONE IS MORE ACCURATE. BUT
EITHER WAY THE FRONT WILL ARRIVE ON SUNDAY AND OPTED TO SLOW THE
ARRIVAL OF THE FRONT BACK A FEW HOURS. THE EXACT TIMING OF THE
FRONT WILL HAVE MORE OF AN IMPACT ON HIGH TEMPS FOR THE DAY THAN
ANY OTHER PART OF THE FORECAST. THE MOISTURE PROFILES STILL LOOK
PRETTY MEAGER ALONG AND AHEAD OF THE FRONT AND KEPT LOW POPS
ACROSS THE REGION...BUT DID INCREASE POPS TO 40 PERCENT IN THE
SOUTHEAST WHERE THE MOISTURE PROFILES LOOK THE BEST. PRECIPITATION
SHOULD QUICKLY END SUNDAY NIGHT BUT NOW THE ECMWF IS SUGGESTING
SOME LIGHT SNOW MIGHT BE POSSIBLE OVER THE NORTHERN COUNTIES
SUNDAY NIGHT. THE ECMWF TEMPERATURE PROFILE IS MUCH COLDER TONIGHT
THAT LAST NIGHT/S RUN AND THIS WILL BE SOMETHING THAT NEEDS TO BE
CLOSELY WATCHED. PREVIOUSLY...FORECAST SOUNDINGS SHOWED THE
ATMOSPHERE QUICKLY DRYING OUT BEHIND THE FRONT...BUT NOW THE GFS
IS SHOWING A LITTLE INCREASE IN MID AND LOW LEVEL MOISTURE SUNDAY
NIGHT. WILL NOT MENTION ANY WINTER PRECIPITATION AT THIS TIME AND
CONTINUE TO ASSESS WITH UPCOMING MODEL RUNS. TEMPERATURES ON
MONDAY WILL REACH THE 40S BUT SOME LOCATIONS NEAR THE RED RIVER
WILL STRUGGLE TO GET INTO THE 40S. MONDAY NIGHT WILL BE A COLD
NIGHT WITH OVERNIGHT LOWS IN THE 20S ACROSS THE REGION.
THE CANADIAN FRONT WILL PUSH DEEP INTO THE GULF OF MEXICO AND THE
UPPER LEVEL TROUGH WILL SWING TO THE EAST COAST BY TUESDAY. ALL
THE MODELS HAVE ANOTHER PIECE OF UPPER LEVEL ENERGY DIVING DOWN
THE ROCKIES AND INTO THE PLAINS BY THE MIDDLE OF NEXT
WEEK...HOWEVER THEIR TRACKS AND TIMING OF THIS SECOND PIECE OF
ENERGY DIFFER CONSIDERABLY. THE GFS IS QUICK TO RETURN MOISTURE
BACK TO THE REGION AHEAD OF THE NEXT TROUGH AND BRINGS ABUNDANT
RAINFALL TO PARTS OF THE REGION. WITH SUNDAYS FRONT PUSHING DEEP
ACROSS THE GULF OF MEXICO...THIS SHOULD PREVENT ANY CHANCE OF LOW
LEVEL MOISTURE QUICKLY RETURNING TO NORTH AND CENTRAL TEXAS AND
WILL KEEP THE FORECAST DRY THROUGH THE END OF THE PERIOD.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 74 52 71 57 76 / 0 5 10 10 10
WACO, TX 74 52 74 60 79 / 0 5 10 10 10
PARIS, TX 65 50 70 56 72 / 0 5 10 10 10
DENTON, TX 73 49 70 53 75 / 0 5 10 10 10
MCKINNEY, TX 70 50 70 56 74 / 0 5 10 10 10
DALLAS, TX 73 54 71 58 77 / 0 5 10 10 10
TERRELL, TX 67 52 70 58 75 / 0 5 10 10 10
CORSICANA, TX 68 54 73 60 77 / 0 5 10 10 10
TEMPLE, TX 74 53 74 61 78 / 0 5 10 10 10
MINERAL WELLS, TX 77 47 70 52 78 / 0 5 10 10 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/75
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
535 AM CST THU DEC 6 2012
.AVIATION...
CIGS AROUND 300 FEET WILL PREVAIL THROUGH THE EARLY MORNING HOURS
BUT SHOULD SLOWLY LIFT TO THE IFR CATEGORY BY/AROUND 16Z/10AM.
VSBY WILL GENERALLY BE NEAR 3-5SM THROUGH 15Z...BUT LOWER VSBY IS
POSSIBLE EARLY THIS MORNING. THE INVERSION SHOULD BREAK AROUND 17Z
TO 18Z AND THE IFR CIGS SHOULD SCATTER QUICKLY AROUND THIS TIME.
VFR WILL PREVAIL THIS AFTERNOON AND EVENING...BUT ANOTHER ROUND OF
CIGS LOOKS PROBABLE LATE TONIGHT. WILL SHOW MVFR CIGS MOVING INTO
TAF SITES AROUND 9Z. THESE CLOUDS MAY BE LOWER IF THE NAM
VERIFIES...BUT SINCE MOISTURE ADVECTION IS WEAKER TONIGHT AND
BOUNDARY LAYER WILL BE WARMER...THEY WILL LIKELY BE HIGHER BASED
THAN THIS MORNING. OTHERWISE SOUTH WINDS WILL PREVAIL AT 10-15 KT
TODAY. TR.92
&&
.PREV DISCUSSION... /ISSUED 356 AM CST THU DEC 6 2012/
WARM AIR ADVECTION ACROSS THE REGION THIS MORNING IS BRINGING
INCREASING DEWPOINTS...LOW STRATUS...AND FOG TO A GOOD PORTION OF
NORTH AND CENTRAL TEXAS. VISIBILITIES WITHIN FOGGY AREAS HAVE
VARIED THROUGH THE NIGHT BUT SEVERAL SITES HAVE REPORTED DENSE
FOG. HOWEVER...SOME SITES THAT PREVIOUSLY REPORTED DENSE FOG HAVE
NOW IMPROVED VISIBILITIES. THE CURRENT DENSE FOG ADVISORY THAT IS
IN EFFECT FOR THE SOUTHEASTERN COUNTIES WILL REMAIN AS IS FOR NOW
BUT ADJUSTMENTS TO THE AREA MAY BE NEEDED BEFORE THE 10 AM
EXPIRATION.
MOST GUIDANCE TONIGHT IS HAVING A HARD TIME WITH THE CLOUDS BUT
THE RAP MODEL AND LAMP MOS GUIDANCE HAVE RECENTLY PICKED UP ON THE
TRENDS. HOWEVER...BOTH OF THESE MODELS SCATTER THE CLOUDS OUT BY
MIDDAY. THE 00Z RUN OF THE 4 KM WRF IS THE ONLY MODEL HOLDING THE
CLOUDS IN OVER THE EASTERN HALF OF THE REGION FOR MUCH OF THE DAY.
WITH DEEP SOUTHERLY FLOW CONTINUING TODAY... WILL SIDE WITH THE
00Z 4 KM WRF AND KEEP MOSTLY CLOUDY CONDITIONS OVER THE EASTERN
HALF OF THE REGION THROUGH MID AFTERNOON. DUE TO THE CLOUD
COVER...HAVE LOWERED HIGH TEMPERATURES OVER THE EASTERN HALF INTO
THE 60S TODAY. THE LATEST RUNS OF THE RAP MODEL ARE ALSO SHOWING
COOL TEMPERATURES OVER THE EASTERN COUNTIES THIS AFTERNOON...BUT
FELT THE RAP/S TEMPERATURES WERE TOO LOW.
STRATUS WILL RETURN AGAIN TONIGHT AND SOME PATCHY FOG WILL ALSO BE
POSSIBLE...MAINLY OVER THE SOUTHEASTERN COUNTIES. THE WINDS
TONIGHT WILL BE SLIGHTLY STRONGER AS A SURFACE LOW MOVES CLOSER
FROM THE NORTHWEST. THEREFORE THE CHANCES FOR DENSE FOG AND/OR
WIDESPREAD FOG ARE LOWER. WITH THE STRONGER WINDS...STRATUS IS
MORE LIKELY BUT WILL CONTINUE TO ASSESS THE FOG POTENTIAL AND
ESPECIALLY THE WIND SPEEDS FOR TONIGHT.
A COLD FRONT THAT IS CURRENTLY MOVING DOWN THE PLAINS AND INTO
NEBRASKA THIS MORNING WILL SLIDE INTO NORTH TEXAS LATE TONIGHT.
THIS FRONT WILL STALL ACROSS THE NORTHWESTERN COUNTIES ON FRIDAY
AND THEN RETREAT NORTH ON SATURDAY AS A STRONG UPPER LEVEL
TROUGH DIVES DOWN THE ROCKIES AND INDUCES LEE-SIDE CYCLOGENESIS.
THE GFS CONTINUES TO BE AGGRESSIVE WITH PUSHING THE FRONT DEEPER
IN OUR AREA THAN THE OTHER MODELS SUGGEST. CURRENT TEMPERATURES
BEHIND THE FRONT ARE IN THE 40S AND THIS AIR WILL CONTINUE TO
MODIFY AS THE FRONT MOVES FARTHER SOUTH. DUE TO THE MODIFIED
NATURE OF THE AIR AND THE ZONAL UPPER LEVEL FLOW PATTERN...DO NOT
THINK THE FRONT WILL MAKE IT MUCH FARTHER THAN THE NORTHWESTERN
COUNTIES.
MOISTURE ADVECTION WILL CONTINUE AHEAD OF THIS FIRST FRONT ON
FRIDAY AND SATURDAY. DEWPOINTS WILL EVENTUALLY REACH THE 60S BY
SATURDAY AND THUS OVERNIGHT LOWS WILL ALSO QUICKLY WARM THIS
WEEKEND. A WEAK ELONGATED SHORTWAVE WILL MOVE OVER THE REGION
FRIDAY NIGHT/SATURDAY MORNING. FORECAST MODELS INDICATE THE LOW
LEVEL MOISTURE DEPTH WILL HAVE INCREASED TO BETWEEN 5-8 KFT BY
THEN AND THE CAP WILL BE WEAKENED ENOUGH FOR SOME AREAS OF LIGHT
RAIN OR SHOWERS TO DEVELOP OVER ROUGHLY THE EASTERN HALF OF THE
REGION. HAVE INTRODUCED 20 POPS FRIDAY NIGHT THROUGH SATURDAY
MORNING ANTICIPATING SCATTERED LIGHT RAIN ACTIVITY OR LIGHT
SHOWERS.
ON SUNDAY...THE UPPER LEVEL TROUGH THAT WAS PREVIOUSLY MENTIONED
OVER THE ROCKIES WILL SWING INTO THE SOUTHERN PLAINS...SENDING A
STRONG CANADIAN COLD FRONT ACROSS THE REGION. THE ECMWF CONTINUES
TO BE THE SLOWEST WITH THE FRONT AND UPPER LEVEL TROUGH WHILE THE
GFS AND NAM ARE THE FASTEST. BOTH THE GFS AND ECMWF HAVE SHOWN
GOOD RUN-TO-RUN CONSISTENCY WITH THEIR RESPECTIVE TIMINGS...THUS
IT IS DIFFICULT TO DETERMINE WHICH ONE IS MORE ACCURATE. BUT
EITHER WAY THE FRONT WILL ARRIVE ON SUNDAY AND OPTED TO SLOW THE
ARRIVAL OF THE FRONT BACK A FEW HOURS. THE EXACT TIMING OF THE
FRONT WILL HAVE MORE OF AN IMPACT ON HIGH TEMPS FOR THE DAY THAN
ANY OTHER PART OF THE FORECAST. THE MOISTURE PROFILES STILL LOOK
PRETTY MEAGER ALONG AND AHEAD OF THE FRONT AND KEPT LOW POPS
ACROSS THE REGION...BUT DID INCREASE POPS TO 40 PERCENT IN THE
SOUTHEAST WHERE THE MOISTURE PROFILES LOOK THE BEST. PRECIPITATION
SHOULD QUICKLY END SUNDAY NIGHT BUT NOW THE ECMWF IS SUGGESTING
SOME LIGHT SNOW MIGHT BE POSSIBLE OVER THE NORTHERN COUNTIES
SUNDAY NIGHT. THE ECMWF TEMPERATURE PROFILE IS MUCH COLDER TONIGHT
THAT LAST NIGHT/S RUN AND THIS WILL BE SOMETHING THAT NEEDS TO BE
CLOSELY WATCHED. PREVIOUSLY...FORECAST SOUNDINGS SHOWED THE
ATMOSPHERE QUICKLY DRYING OUT BEHIND THE FRONT...BUT NOW THE GFS
IS SHOWING A LITTLE INCREASE IN MID AND LOW LEVEL MOISTURE SUNDAY
NIGHT. WILL NOT MENTION ANY WINTER PRECIPITATION AT THIS TIME AND
CONTINUE TO ASSESS WITH UPCOMING MODEL RUNS. TEMPERATURES ON
MONDAY WILL REACH THE 40S BUT SOME LOCATIONS NEAR THE RED RIVER
WILL STRUGGLE TO GET INTO THE 40S. MONDAY NIGHT WILL BE A COLD
NIGHT WITH OVERNIGHT LOWS IN THE 20S ACROSS THE REGION.
THE CANADIAN FRONT WILL PUSH DEEP INTO THE GULF OF MEXICO AND THE
UPPER LEVEL TROUGH WILL SWING TO THE EAST COAST BY TUESDAY. ALL
THE MODELS HAVE ANOTHER PIECE OF UPPER LEVEL ENERGY DIVING DOWN
THE ROCKIES AND INTO THE PLAINS BY THE MIDDLE OF NEXT
WEEK...HOWEVER THEIR TRACKS AND TIMING OF THIS SECOND PIECE OF
ENERGY DIFFER CONSIDERABLY. THE GFS IS QUICK TO RETURN MOISTURE
BACK TO THE REGION AHEAD OF THE NEXT TROUGH AND BRINGS ABUNDANT
RAINFALL TO PARTS OF THE REGION. WITH SUNDAYS FRONT PUSHING DEEP
ACROSS THE GULF OF MEXICO...THIS SHOULD PREVENT ANY CHANCE OF LOW
LEVEL MOISTURE QUICKLY RETURNING TO NORTH AND CENTRAL TEXAS AND
WILL KEEP THE FORECAST DRY THROUGH THE END OF THE PERIOD.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 74 52 71 57 76 / 0 5 10 20 20
WACO, TX 74 52 74 60 79 / 5 5 10 20 20
PARIS, TX 65 50 70 56 72 / 0 5 10 20 20
DENTON, TX 73 49 70 53 75 / 0 5 10 10 10
MCKINNEY, TX 70 50 70 56 74 / 0 5 10 20 20
DALLAS, TX 73 54 71 58 77 / 0 5 10 20 20
TERRELL, TX 67 52 70 58 75 / 0 5 10 20 20
CORSICANA, TX 68 54 73 60 77 / 5 5 10 20 20
TEMPLE, TX 74 53 74 61 78 / 5 5 10 20 20
MINERAL WELLS, TX 77 47 70 52 78 / 0 5 10 10 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
515 AM CST THU DEC 6 2012
.UPDATE...
DENSE FOG FORMED IN SOME OF THE SOUTHEASTERN COUNTIES THIS MORNING
ALONG AN INITIAL SURGE OF MOISTURE THAT IS SPREADING NORTH ACROSS
THE REGION. HOWEVER...VISIBILITIES HAVE NOW IMPROVED TO ONE MILE
OR GREATER ACROSS THE ADVISORY AREA AND THE ADVISORY HAS BEEN
CANCELLED. A FEW ISOLATED AREAS OF DENSE FOG WILL STILL BE
POSSIBLE ACROSS ALL OF NORTH AND CENTRAL TEXAS THROUGH 8 OR 9 AM
BUT MOST LOCATIONS SHOULD REMAIN ABOVE 1/4 MILE.
82/JLD
&&
.PREV DISCUSSION... /ISSUED 356 AM CST THU DEC 6 2012/
WARM AIR ADVECTION ACROSS THE REGION THIS MORNING IS BRINGING
INCREASING DEWPOINTS...LOW STRATUS...AND FOG TO A GOOD PORTION OF
NORTH AND CENTRAL TEXAS. VISIBILITIES WITHIN FOGGY AREAS HAVE
VARIED THROUGH THE NIGHT BUT SEVERAL SITES HAVE REPORTED DENSE
FOG. HOWEVER...SOME SITES THAT PREVIOUSLY REPORTED DENSE FOG HAVE
NOW IMPROVED VISIBILITIES. THE CURRENT DENSE FOG ADVISORY THAT IS
IN EFFECT FOR THE SOUTHEASTERN COUNTIES WILL REMAIN AS IS FOR NOW
BUT ADJUSTMENTS TO THE AREA MAY BE NEEDED BEFORE THE 10 AM
EXPIRATION.
MOST GUIDANCE TONIGHT IS HAVING A HARD TIME WITH THE CLOUDS BUT
THE RAP MODEL AND LAMP MOS GUIDANCE HAVE RECENTLY PICKED UP ON THE
TRENDS. HOWEVER...BOTH OF THESE MODELS SCATTER THE CLOUDS OUT BY
MIDDAY. THE 00Z RUN OF THE 4 KM WRF IS THE ONLY MODEL HOLDING THE
CLOUDS IN OVER THE EASTERN HALF OF THE REGION FOR MUCH OF THE DAY.
WITH DEEP SOUTHERLY FLOW CONTINUING TODAY... WILL SIDE WITH THE
00Z 4 KM WRF AND KEEP MOSTLY CLOUDY CONDITIONS OVER THE EASTERN
HALF OF THE REGION THROUGH MID AFTERNOON. DUE TO THE CLOUD
COVER...HAVE LOWERED HIGH TEMPERATURES OVER THE EASTERN HALF INTO
THE 60S TODAY. THE LATEST RUNS OF THE RAP MODEL ARE ALSO SHOWING
COOL TEMPERATURES OVER THE EASTERN COUNTIES THIS AFTERNOON...BUT
FELT THE RAP/S TEMPERATURES WERE TOO LOW.
STRATUS WILL RETURN AGAIN TONIGHT AND SOME PATCHY FOG WILL ALSO BE
POSSIBLE...MAINLY OVER THE SOUTHEASTERN COUNTIES. THE WINDS
TONIGHT WILL BE SLIGHTLY STRONGER AS A SURFACE LOW MOVES CLOSER
FROM THE NORTHWEST. THEREFORE THE CHANCES FOR DENSE FOG AND/OR
WIDESPREAD FOG ARE LOWER. WITH THE STRONGER WINDS...STRATUS IS
MORE LIKELY BUT WILL CONTINUE TO ASSESS THE FOG POTENTIAL AND
ESPECIALLY THE WIND SPEEDS FOR TONIGHT.
A COLD FRONT THAT IS CURRENTLY MOVING DOWN THE PLAINS AND INTO
NEBRASKA THIS MORNING WILL SLIDE INTO NORTH TEXAS LATE TONIGHT.
THIS FRONT WILL STALL ACROSS THE NORTHWESTERN COUNTIES ON FRIDAY
AND THEN RETREAT NORTH ON SATURDAY AS A STRONG UPPER LEVEL
TROUGH DIVES DOWN THE ROCKIES AND INDUCES LEE-SIDE CYCLOGENESIS.
THE GFS CONTINUES TO BE AGGRESSIVE WITH PUSHING THE FRONT DEEPER
IN OUR AREA THAN THE OTHER MODELS SUGGEST. CURRENT TEMPERATURES
BEHIND THE FRONT ARE IN THE 40S AND THIS AIR WILL CONTINUE TO
MODIFY AS THE FRONT MOVES FARTHER SOUTH. DUE TO THE MODIFIED
NATURE OF THE AIR AND THE ZONAL UPPER LEVEL FLOW PATTERN...DO NOT
THINK THE FRONT WILL MAKE IT MUCH FARTHER THAN THE NORTHWESTERN
COUNTIES.
MOISTURE ADVECTION WILL CONTINUE AHEAD OF THIS FIRST FRONT ON
FRIDAY AND SATURDAY. DEWPOINTS WILL EVENTUALLY REACH THE 60S BY
SATURDAY AND THUS OVERNIGHT LOWS WILL ALSO QUICKLY WARM THIS
WEEKEND. A WEAK ELONGATED SHORTWAVE WILL MOVE OVER THE REGION
FRIDAY NIGHT/SATURDAY MORNING. FORECAST MODELS INDICATE THE LOW
LEVEL MOISTURE DEPTH WILL HAVE INCREASED TO BETWEEN 5-8 KFT BY
THEN AND THE CAP WILL BE WEAKENED ENOUGH FOR SOME AREAS OF LIGHT
RAIN OR SHOWERS TO DEVELOP OVER ROUGHLY THE EASTERN HALF OF THE
REGION. HAVE INTRODUCED 20 POPS FRIDAY NIGHT THROUGH SATURDAY
MORNING ANTICIPATING SCATTERED LIGHT RAIN ACTIVITY OR LIGHT
SHOWERS.
ON SUNDAY...THE UPPER LEVEL TROUGH THAT WAS PREVIOUSLY MENTIONED
OVER THE ROCKIES WILL SWING INTO THE SOUTHERN PLAINS...SENDING A
STRONG CANADIAN COLD FRONT ACROSS THE REGION. THE ECMWF CONTINUES
TO BE THE SLOWEST WITH THE FRONT AND UPPER LEVEL TROUGH WHILE THE
GFS AND NAM ARE THE FASTEST. BOTH THE GFS AND ECMWF HAVE SHOWN
GOOD RUN-TO-RUN CONSISTENCY WITH THEIR RESPECTIVE TIMINGS...THUS
IT IS DIFFICULT TO DETERMINE WHICH ONE IS MORE ACCURATE. BUT
EITHER WAY THE FRONT WILL ARRIVE ON SUNDAY AND OPTED TO SLOW THE
ARRIVAL OF THE FRONT BACK A FEW HOURS. THE EXACT TIMING OF THE
FRONT WILL HAVE MORE OF AN IMPACT ON HIGH TEMPS FOR THE DAY THAN
ANY OTHER PART OF THE FORECAST. THE MOISTURE PROFILES STILL LOOK
PRETTY MEAGER ALONG AND AHEAD OF THE FRONT AND KEPT LOW POPS
ACROSS THE REGION...BUT DID INCREASE POPS TO 40 PERCENT IN THE
SOUTHEAST WHERE THE MOISTURE PROFILES LOOK THE BEST. PRECIPITATION
SHOULD QUICKLY END SUNDAY NIGHT BUT NOW THE ECMWF IS SUGGESTING
SOME LIGHT SNOW MIGHT BE POSSIBLE OVER THE NORTHERN COUNTIES
SUNDAY NIGHT. THE ECMWF TEMPERATURE PROFILE IS MUCH COLDER TONIGHT
THAT LAST NIGHT/S RUN AND THIS WILL BE SOMETHING THAT NEEDS TO BE
CLOSELY WATCHED. PREVIOUSLY...FORECAST SOUNDINGS SHOWED THE
ATMOSPHERE QUICKLY DRYING OUT BEHIND THE FRONT...BUT NOW THE GFS
IS SHOWING A LITTLE INCREASE IN MID AND LOW LEVEL MOISTURE SUNDAY
NIGHT. WILL NOT MENTION ANY WINTER PRECIPITATION AT THIS TIME AND
CONTINUE TO ASSESS WITH UPCOMING MODEL RUNS. TEMPERATURES ON
MONDAY WILL REACH THE 40S BUT SOME LOCATIONS NEAR THE RED RIVER
WILL STRUGGLE TO GET INTO THE 40S. MONDAY NIGHT WILL BE A COLD
NIGHT WITH OVERNIGHT LOWS IN THE 20S ACROSS THE REGION.
THE CANADIAN FRONT WILL PUSH DEEP INTO THE GULF OF MEXICO AND THE
UPPER LEVEL TROUGH WILL SWING TO THE EAST COAST BY TUESDAY. ALL
THE MODELS HAVE ANOTHER PIECE OF UPPER LEVEL ENERGY DIVING DOWN
THE ROCKIES AND INTO THE PLAINS BY THE MIDDLE OF NEXT
WEEK...HOWEVER THEIR TRACKS AND TIMING OF THIS SECOND PIECE OF
ENERGY DIFFER CONSIDERABLY. THE GFS IS QUICK TO RETURN MOISTURE
BACK TO THE REGION AHEAD OF THE NEXT TROUGH AND BRINGS ABUNDANT
RAINFALL TO PARTS OF THE REGION. WITH SUNDAYS FRONT PUSHING DEEP
ACROSS THE GULF OF MEXICO...THIS SHOULD PREVENT ANY CHANCE OF LOW
LEVEL MOISTURE QUICKLY RETURNING TO NORTH AND CENTRAL TEXAS AND
WILL KEEP THE FORECAST DRY THROUGH THE END OF THE PERIOD.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 74 52 71 57 76 / 0 5 10 20 20
WACO, TX 74 52 74 60 79 / 5 5 10 20 20
PARIS, TX 65 50 70 56 72 / 0 5 10 20 20
DENTON, TX 73 49 70 53 75 / 0 5 10 10 10
MCKINNEY, TX 70 50 70 56 74 / 0 5 10 20 20
DALLAS, TX 73 54 71 58 77 / 0 5 10 20 20
TERRELL, TX 67 52 70 58 75 / 0 5 10 20 20
CORSICANA, TX 68 54 73 60 77 / 5 5 10 20 20
TEMPLE, TX 74 53 74 61 78 / 5 5 10 20 20
MINERAL WELLS, TX 77 47 70 52 78 / 0 5 10 10 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR TXZ121-
122-134-135-146>148-160>162-174-175.
&&
$$
92/82
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
356 AM CST THU DEC 6 2012
.DISCUSSION...
WARM AIR ADVECTION ACROSS THE REGION THIS MORNING IS BRINGING
INCREASING DEWPOINTS...LOW STRATUS...AND FOG TO A GOOD PORTION OF
NORTH AND CENTRAL TEXAS. VISIBILITIES WITHIN FOGGY AREAS HAVE
VARIED THROUGH THE NIGHT BUT SEVERAL SITES HAVE REPORTED DENSE
FOG. HOWEVER...SOME SITES THAT PREVIOUSLY REPORTED DENSE FOG HAVE
NOW IMPROVED VISIBILITIES. THE CURRENT DENSE FOG ADVISORY THAT IS
IN EFFECT FOR THE SOUTHEASTERN COUNTIES WILL REMAIN AS IS FOR NOW
BUT ADJUSTMENTS TO THE AREA MAY BE NEEDED BEFORE THE 10 AM
EXPIRATION.
MOST GUIDANCE TONIGHT IS HAVING A HARD TIME WITH THE CLOUDS BUT
THE RAP MODEL AND LAMP MOS GUIDANCE HAVE RECENTLY PICKED UP ON THE
TRENDS. HOWEVER...BOTH OF THESE MODELS SCATTER THE CLOUDS OUT BY
MIDDAY. THE 00Z RUN OF THE 4 KM WRF IS THE ONLY MODEL HOLDING THE
CLOUDS IN OVER THE EASTERN HALF OF THE REGION FOR MUCH OF THE DAY.
WITH DEEP SOUTHERLY FLOW CONTINUING TODAY... WILL SIDE WITH THE
00Z 4 KM WRF AND KEEP MOSTLY CLOUDY CONDITIONS OVER THE EASTERN
HALF OF THE REGION THROUGH MID AFTERNOON. DUE TO THE CLOUD
COVER...HAVE LOWERED HIGH TEMPERATURES OVER THE EASTERN HALF INTO
THE 60S TODAY. THE LATEST RUNS OF THE RAP MODEL ARE ALSO SHOWING
COOL TEMPERATURES OVER THE EASTERN COUNTIES THIS AFTERNOON...BUT
FELT THE RAP/S TEMPERATURES WERE TOO LOW.
STRATUS WILL RETURN AGAIN TONIGHT AND SOME PATCHY FOG WILL ALSO BE
POSSIBLE...MAINLY OVER THE SOUTHEASTERN COUNTIES. THE WINDS
TONIGHT WILL BE SLIGHTLY STRONGER AS A SURFACE LOW MOVES CLOSER
FROM THE NORTHWEST. THEREFORE THE CHANCES FOR DENSE FOG AND/OR
WIDESPREAD FOG ARE LOWER. WITH THE STRONGER WINDS...STRATUS IS
MORE LIKELY BUT WILL CONTINUE TO ASSESS THE FOG POTENTIAL AND
ESPECIALLY THE WIND SPEEDS FOR TONIGHT.
A COLD FRONT THAT IS CURRENTLY MOVING DOWN THE PLAINS AND INTO
NEBRASKA THIS MORNING WILL SLIDE INTO NORTH TEXAS LATE TONIGHT.
THIS FRONT WILL STALL ACROSS THE NORTHWESTERN COUNTIES ON FRIDAY
AND THEN RETREAT NORTH ON SATURDAY AS A STRONG UPPER LEVEL
TROUGH DIVES DOWN THE ROCKIES AND INDUCES LEE-SIDE CYCLOGENESIS.
THE GFS CONTINUES TO BE AGGRESSIVE WITH PUSHING THE FRONT DEEPER
IN OUR AREA THAN THE OTHER MODELS SUGGEST. CURRENT TEMPERATURES
BEHIND THE FRONT ARE IN THE 40S AND THIS AIR WILL CONTINUE TO
MODIFY AS THE FRONT MOVES FARTHER SOUTH. DUE TO THE MODIFIED
NATURE OF THE AIR AND THE ZONAL UPPER LEVEL FLOW PATTERN...DO NOT
THINK THE FRONT WILL MAKE IT MUCH FARTHER THAN THE NORTHWESTERN
COUNTIES.
MOISTURE ADVECTION WILL CONTINUE AHEAD OF THIS FIRST FRONT ON
FRIDAY AND SATURDAY. DEWPOINTS WILL EVENTUALLY REACH THE 60S BY
SATURDAY AND THUS OVERNIGHT LOWS WILL ALSO QUICKLY WARM THIS
WEEKEND. A WEAK ELONGATED SHORTWAVE WILL MOVE OVER THE REGION
FRIDAY NIGHT/SATURDAY MORNING. FORECAST MODELS INDICATE THE LOW
LEVEL MOISTURE DEPTH WILL HAVE INCREASED TO BETWEEN 5-8 KFT BY
THEN AND THE CAP WILL BE WEAKENED ENOUGH FOR SOME AREAS OF LIGHT
RAIN OR SHOWERS TO DEVELOP OVER ROUGHLY THE EASTERN HALF OF THE
REGION. HAVE INTRODUCED 20 POPS FRIDAY NIGHT THROUGH SATURDAY
MORNING ANTICIPATING SCATTERED LIGHT RAIN ACTIVITY OR LIGHT
SHOWERS.
ON SUNDAY...THE UPPER LEVEL TROUGH THAT WAS PREVIOUSLY MENTIONED
OVER THE ROCKIES WILL SWING INTO THE SOUTHERN PLAINS...SENDING A
STRONG CANADIAN COLD FRONT ACROSS THE REGION. THE ECMWF CONTINUES
TO BE THE SLOWEST WITH THE FRONT AND UPPER LEVEL TROUGH WHILE THE
GFS AND NAM ARE THE FASTEST. BOTH THE GFS AND ECMWF HAVE SHOWN
GOOD RUN-TO-RUN CONSISTENCY WITH THEIR RESPECTIVE TIMINGS...THUS
IT IS DIFFICULT TO DETERMINE WHICH ONE IS MORE ACCURATE. BUT
EITHER WAY THE FRONT WILL ARRIVE ON SUNDAY AND OPTED TO SLOW THE
ARRIVAL OF THE FRONT BACK A FEW HOURS. THE EXACT TIMING OF THE
FRONT WILL HAVE MORE OF AN IMPACT ON HIGH TEMPS FOR THE DAY THAN
ANY OTHER PART OF THE FORECAST. THE MOISTURE PROFILES STILL LOOK
PRETTY MEAGER ALONG AND AHEAD OF THE FRONT AND KEPT LOW POPS
ACROSS THE REGION...BUT DID INCREASE POPS TO 40 PERCENT IN THE
SOUTHEAST WHERE THE MOISTURE PROFILES LOOK THE BEST. PRECIPITATION
SHOULD QUICKLY END SUNDAY NIGHT BUT NOW THE ECMWF IS SUGGESTING
SOME LIGHT SNOW MIGHT BE POSSIBLE OVER THE NORTHERN COUNTIES
SUNDAY NIGHT. THE ECMWF TEMPERATURE PROFILE IS MUCH COLDER TONIGHT
THAT LAST NIGHT/S RUN AND THIS WILL BE SOMETHING THAT NEEDS TO BE
CLOSELY WATCHED. PREVIOUSLY...FORECAST SOUNDINGS SHOWED THE
ATMOSPHERE QUICKLY DRYING OUT BEHIND THE FRONT...BUT NOW THE GFS
IS SHOWING A LITTLE INCREASE IN MID AND LOW LEVEL MOISTURE SUNDAY
NIGHT. WILL NOT MENTION ANY WINTER PRECIPITATION AT THIS TIME AND
CONTINUE TO ASSESS WITH UPCOMING MODEL RUNS. TEMPERATURES ON
MONDAY WILL REACH THE 40S BUT SOME LOCATIONS NEAR THE RED RIVER
WILL STRUGGLE TO GET INTO THE 40S. MONDAY NIGHT WILL BE A COLD
NIGHT WITH OVERNIGHT LOWS IN THE 20S ACROSS THE REGION.
THE CANADIAN FRONT WILL PUSH DEEP INTO THE GULF OF MEXICO AND THE
UPPER LEVEL TROUGH WILL SWING TO THE EAST COAST BY TUESDAY. ALL
THE MODELS HAVE ANOTHER PIECE OF UPPER LEVEL ENERGY DIVING DOWN
THE ROCKIES AND INTO THE PLAINS BY THE MIDDLE OF NEXT
WEEK...HOWEVER THEIR TRACKS AND TIMING OF THIS SECOND PIECE OF
ENERGY DIFFER CONSIDERABLY. THE GFS IS QUICK TO RETURN MOISTURE
BACK TO THE REGION AHEAD OF THE NEXT TROUGH AND BRINGS ABUNDANT
RAINFALL TO PARTS OF THE REGION. WITH SUNDAYS FRONT PUSHING DEEP
ACROSS THE GULF OF MEXICO...THIS SHOULD PREVENT ANY CHANCE OF LOW
LEVEL MOISTURE QUICKLY RETURNING TO NORTH AND CENTRAL TEXAS AND
WILL KEEP THE FORECAST DRY THROUGH THE END OF THE PERIOD.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 74 50 71 57 75 / 0 5 10 5 10
WACO, TX 72 52 73 60 76 / 0 5 10 5 10
PARIS, TX 70 52 72 55 72 / 0 5 10 20 10
DENTON, TX 73 48 71 54 75 / 0 5 10 10 10
MCKINNEY, TX 71 51 71 56 75 / 0 5 10 10 10
DALLAS, TX 73 51 71 58 75 / 0 5 10 10 10
TERRELL, TX 73 53 74 60 77 / 0 5 10 10 10
CORSICANA, TX 74 53 76 61 77 / 0 5 10 10 10
TEMPLE, TX 73 53 76 61 77 / 0 5 10 5 10
MINERAL WELLS, TX 76 46 75 51 76 / 0 5 10 5 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR TXZ121-122-
134-135-146>148-160>162-174-175.
&&
$$
92/82
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
122 AM CST THU DEC 6 2012
.UPDATE...
AREAS OF FOG HAVE DEVELOPED ACROSS SE TX TONIGHT. AT TIMES...
PATCHY AREAS HAVE BECOME DENSE. THE LATEST RUC FORECAST SHOWS
DEWPOINT DEPRESSIONS WILL BECOME 2 DEGREES OR LESS THROUGH
SUNRISE. ALSO NOTED THAT THE HIGHER LEVEL CLOUDINESS WAS MOVING
EAST AND SOUTHEAST OF THE AREA. THE THINKING HERE IS THAT AS IT
DOES SO...MORE WIDESPREAD FOG AND AREAS OF DENSE FOG WILL DEVELOP.
WITH THAT IN MIND...ISSUING A DENSE FOG ADVISORY THROUGH 10 AM.
40
&&
.PREV DISCUSSION... /ISSUED 854 PM CST WED DEC 5 2012/
DISCUSSION...
AREAS OF FOG DEVELOPING ACROSS W/SW PARTS OF THE REGION...WHERE
SKIES HAVE CLEARED OUT. OVC CLOUD DECK PERSISTS GENERALLY ALONG
& E OF THE I-45 CORRIDOR. MODELS VARY WHETHER THESE SCATTER OUT OR
HANG TIGHT AND FCST CONFIDENCE IS LOW. ONE THING I AM CONFIDENT
ABOUT THOUGH IS THAT FOG WILL QUICKLY DEVELOP WHERE THERE ARE ANY
BREAKS WITH THE T/TD SPREAD IS CURRENTLY ONLY A FEW DEGREES. WOULD
NOT BE SURPRISED TO SEE A DENSE FOG ADVSY FOR PARTS OF THE AREA.
GOING TO LOOK AT THE 9PM OBS AND MAY START OUT WITH ONE ACROSS SW
PARTS SHORTLY...
FCST IS IN GOOD SHAPE. FOR THE UPDATE...JUST TWEAKED GRIDS TO
MATCH CURRENT TRENDS AND ADVERTISE AN EARLIER START TO THE FOG. 47
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 57 78 62 79 62 / 10 10 10 20 10
HOUSTON (IAH) 57 78 63 79 63 / 10 10 10 20 10
GALVESTON (GLS) 62 75 65 76 65 / 10 10 10 20 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR THE
FOLLOWING ZONES: AUSTIN...BRAZORIA...BRAZOS...BURLESON...
CHAMBERS...COLORADO...FORT BEND...GALVESTON...GRIMES...
HARRIS...HOUSTON...JACKSON...LIBERTY...MADISON...
MATAGORDA...MONTGOMERY...POLK...SAN JACINTO...TRINITY...
WALKER...WALLER...WASHINGTON...WHARTON.
GM...NONE.
&&
$$
DISCUSSION...40
AVIATION/MARINE...38
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
243 PM CST THU DEC 6 2012
.SHORT TERM...
TONIGHT - CONFIDENCE...MEDIUM
RUC/WATER VAPOR COMBO SHOWS DECENT JET MAX RACING NORTHEAST FROM IOWA
INTO WISCONSIN. RUC SHOWS A COUPLE DIFFERENT VORT CENTERS...ONE IN
CENTRAL WI AND ANOTHER IN WESTERN IOWA. SURFACE/850 TROUGHS EXIT TO
THE EAST. MODELS ALL LINGER A BIT OF QPF IN THE FAR SOUTHEAST SO
WILL KEEP SOME SMALL POPS THERE. STILL QUITE A BIT OF MID CLOUDS
UPSTREAM SO THINK CLOUDY/MOSTLY CLOUDY MUCH OF THE NIGHT.
FRIDAY - CONFIDENCE...MEDIUM
GENTLE COLD ADVECTION WITH BROAD RIDGE OF HIGH PRESSURE ACROSS THE
AREA. WITH A BRISK WSW UPPER FLOW EXPECT TO SEE A SOME MID CLOUDS
AROUND. BUFKIT/RH PROGS AND MOS IMPLY THIS. 925 TEMPS HANG AROUND 0.
LIGHT NE WIND REGIME.
.FRIDAY NIGHT AND SATURDAY...FORECAST CONFIDENCE MEDIUM
GFS EUROPEAN AND NAM MODELS IN GOOD AGREEMENT THAT A WEAK SURFACE
COLD FRONT MOVES ACROSS THE AREA FRIDAY NIGHT ASSOCIATED WITH
SURFACE LOW PRESSURE NORTH OF THE GREAT LAKES. MODELS DEPICT THIS
DRY FRONTAL PASSAGE DEVELOPING SOME PRECIPITATION AS IT MOVES INTO
ILLINOIS SATURDAY...SO SLIGHT CHANCE OF RAIN SNOW MIX OVER EXTREME
SOUTHEAST WISCONSIN EARLY SATURDAY POSSIBLE. LIGHT NORTH WINDS
EARLY SATURDAY BECOME EAST IN THE AFTERNOON. EASTERLY WINDS OFF OF
LAKE MICHIGAN WHICH IS IN THE LOWER 40S SHOULD KEEP HIGH
TEMPERATURES IN THE 40S.
.SATURDAY NIGHT THROUGH SUNDAY NIGHT...FORECAST CONFIDENCE HIGH FOR
PRECIPITATION...MEDIUM FOR PRECIPITATION TYPE
THIS IS THE BEST TIME FOR SIGNIFICANT PRECIPITATION. MOSTLY RAIN IN
THE EXTREME SOUTHEAST BECOMING A RAIN AND SNOW MIX AROUND MADISON
AND FARTHER NORTHWEST INRO CENTRAL WISCONSIN. A COMPLEX MULTIPLE
SURFACE LOW CENTERED OVER MINNESOTA TO WESTERN ILLINOIS SATURDAY
NIGHT WILL MOVE ACROSS WISCONSIN SUNDAY AHEAD OF A STRONG MID
LEVEL SHORTWAVE TROUGH.
RELATIVELY WARM SOUTHEASTERLY WINDS SATURDAY NIGHT WILL BECOME
SOUTHERLY BY SUNDAY MORNING. THE FORECAST CHALLENGE IS DETERMINGING
THE TIMING AND LOCATION OF A RAIN SNOW BOUNDARY WHICH WILL MOVE
NORTHWARD SUNDAY ACROSS SOUTHEASTERN WISCONSIN...BRINGING RAIN TO
SOUTHEAST WISCONSIN CHANGING TO RAIN SNOW MIX IN SOUTH CENTRAL
WISCONSIN. TOTAL PRECIPITATION AMOUNTS OF ONE-QUARTER TO ONE-HALF
INCH ARE EXPECTED FROM SATURDAY NIGHT TROUGH SUNDAY NIGHT WITH
HEAVIEST PRECIPITAION RATES EXPECTED EARLY SUNDAY. AS THE SUFACE
LOW MOVES ACROSS THE AREA SUNDAY AFTERNOON WINDS WILL BECOME
NORTHERLY AND SURFACE TEMPERATURES ABOVE FREEZING ACROSS THE
COUNTY WARNING AREA SUNDAY WILL DROP BELOW FREEZING OVERNIGHT AS
THE PRECIPITATION MOVES EASWARD AND ENDS SUNDAY NIGHT. NO SNOW
ACCUMULATION EXPECTED IN SOUTHEAST WISCONSIN...SOME MINOR
ACCUMULATIONS POSSIBLE LATE SUNDAY NORTHWEST OF MADISON.
.LONG TERM...
.MONDAY THROUGH THURSDAY...FORECAST CONFIDENCE...MEDIUM
NORTHWEST WINDS MONDAY WILL KEEP HIGH TEMPERATURES AROUND
FREEZING CLOSE TO LAKE MICHIGAN TO UPPER 20S INLAND AS SURFACE
HIGH PRESSURE BUILDS OVER THE REGION MONDAY AND MONDAY NIGHT.
SURFACE HIGH PRESSURE SOUTHEAST OF THE REGION WITH THE JET STREAM
NORTH ALONG THE CANADIAN BORDER KEEPS UPPER DISTURBANCES NORTH OF
THE AREA TUESDAY THROUGH THURSDAY.
LITTLE CHANCE OF PRECIPITATION MIDWEEK WITH SEASONABLE
TEMPERATURES.
&&
.AVIATION/00Z TAFS/...
MID DECK CONTINUES TO STREAM ACROSS SRN WI WITH UPPER JET MAX AND
SHORTWAVE TROUGH SWINGING THROUGH. PRECIP REPORTS SPOTTY AT BEST
WITH DRY LOW LEVELS. MODELS TEND TO DRY THE PRECIP UP AS IT MAKES
A MORE EASTWARD TREK FURTHER THROUGH SRN WI.
&&
.MARINE...WILL TRIM OFF THE SRN PORTION OF THE SCA AS WINDS HAVE
EASED UP. HOWEVER STILL QUITE GUSTY AROUND SHEBOYGAN SO WILL LET
THAT PORTION RIDE FOR NOW.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR LMZ643.
&&
$$
TONIGHT/FRIDAY AND AVIATION/MARINE...COLLAR
FRIDAY NIGHT THROUGH THURSDAY...SLB
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1047 PM CST WED DEC 5 2012
.SHORT TERM...TONIGHT AND THURSDAY
728 PM CST WED DEC 5 2012
UPDATE CONCERN IS ON PRECIPITATION CHANCES FOR LATE TONIGHT INTO
THURSDAY MORNING AS WELL AS ANY NEED FOR AN ADVISORY ACROSS TAYLOR
AND CLARK COUNTIES.
01Z WATER VAPOR LOOP SHOWED A SHORTWAVE TROUGH CROSSING SOUTHERN
SASKATCHEWAN INTO EASTERN MONTANA. AHEAD OF THIS SHORTWAVE
TROUGH...A LARGE PLUME OF MOISTURE ON WATER VAPOR ENCOMPASSED MUCH
OF THE NORTHERN PLAINS INTO THE FORECAST AREA. THIS PLUME WAS
NOTED ON IR AND SURFACE OBSERVATIONS AS A CIRROSTRATUS DECK. ALSO
AHEAD OF THE SHORTWAVE WAS A 30-40 KT JET AT 850MB AND 925MB
EXTENDING FROM KANSAS AND MISSOURI INTO SOUTHERN MINNESOTA PER
RADAR VWP AND PROFILER DATA. SOUTHEAST 10-20 KT WERE OCCURRING AT
THE SURFACE FROM ST LOUIS TO SIOUX FALLS SOUTH DAKOTA...BETWEEN
HIGH PRESSURE IN LOWER MICHIGAN AND A COLD FRONT IN THE CENTRAL
DAKOTAS...HELPING TO TRANSPORT HIGHER DEWPOINTS BACK TO THE
NORTHWEST. THE DEWPOINTS AT DES MOINES AND SIOUX FALLS HAVE CLIMBED
NEARLY 12F IN THE PAST 12 HOURS...REACHING 31F AND 26F
RESPECTIVELY. DESPITE THE INCREASED SURFACE MOISTURE...00Z
SOUNDINGS FROM ABR...MPX...DVN AND OAX DEPICT PLENTY OF DRY AIR
BELOW 650MB. THE AFOREMENTIONED LOW LEVEL JET HAS TRANSPORTED
WARMER AIR ALOFT INTO THE NORTHERN PLAINS...WITH A WARM NOSE OF 8C
AT 890 MB AT MPX AND 11C AT 837MB AT ABR. WET-BULBING OF THE MPX
SOUNDING RESULTS IN NEARLY THE ENTIRE SOUNDING AT OR BELOW FREEZING.
AS THE NIGHT PROGRESSES...MORE AND MORE MOISTURE ADVECTS INTO
MINNESOTA FROM EASTERN MISSOURI. MEANWHILE...ISENTROPIC LIFT
INCREASES ON THE 285-305K SURFACES...OR 900-600MB...AS THE
SHORTWAVE TROUGH IN EASTERN MONTANA AND SASKATCHEWAN SHIFTS EAST
INTO NORTH DAKOTA AND MANITOBA. IT WILL TAKE SOME TIME FOR THIS
ISENTROPIC LIFT TO DEVELOP PRECIPITATION...GIVEN ALL OF THE DRY
AIR PRESENT ON 00Z SOUNDINGS. HOWEVER...EXTREMELY GOOD MODEL
AGREEMENT EXISTS THAT AROUND 09Z...A NORTHEAST TO SOUTHWEST
ORIENTED BAND OF PRECIPITATION WILL FORM ACROSS MUCH OF CENTRAL
MINNESOTA JUST AHEAD OF THE COLD FRONT PUSHING EAST. IT IS EVEN
POSSIBLE SOME WARM ADVECTION PRECIPITATION DEVELOPS FARTHER EAST-
NORTHEAST OF THIS BAND ACROSS NORTH CENTRAL WISCONSIN...THOUGH
CONFIDENCE BASED ON MODEL CONSENSUS IS GREATER BACK IN MINNESOTA.
FROM 09-15Z...THE BAND PUSHES EAST...AFFECTING THE NORTHWEST THIRD
OR SO OF THE FORECAST AREA...WITH THE GREATEST CHANCE OF SEEING
PRECIPITATION IN THE 12-15Z TIME PERIOD. THE PRECIPITATION THEN
LOOKS TO DIMINISH PRETTY QUICKLY AS THE LOW LEVEL JET/ISENTROPIC
LIFT FORCING WEAKENS AND THE SHORTWAVE TROUGH LIFTS NORTHEAST. BY
18Z...IT IS POSSIBLE ALL PRECIPITATION WILL HAVE DISSIPATED.
OVERALL PRECIPITATION LOOKS LIGHT...UPWARDS OF ONE TENTH OF AN
INCH...LIMITED BY THE DRY LOWER LEVELS.
PRECIPITATION TYPE IS DEFINITELY A CONCERN...GIVEN THE WET-BULBING
POTENTIAL WHILE WARM ADVECTION IS TAKING PLACE SIMULTANEOUSLY.
MOST LOCATIONS SOUTH AND WEST OF I-94 WILL HAVE A DEEP...WARM AND MOIST
ENOUGH LOW LEVELS TO KEEP THE TYPE AS RAIN. TO THE NORTH OF
I-94...SURFACE TEMPERATURES MAY FLUCTUATE NEAR FREEZING FROM THE
ONSET THROUGH ABOUT 14Z BEFORE FINALLY WARMING AS WINDS TURN
SOUTHWESTERLY. MEANWHILE...THE WARM LAYER ALOFT...WARM ADVECTION
AND WET-BULBING WILL CAUSE PRECIPITATION TO FLUCTUATE BETWEEN
LIQUID...SLEET AND SNOW...DEPENDING ON PRECIPITATION RATE.
CONSIDERED THE IDEA OF ISSUING A WINTER WEATHER ADVISORY FOR
TAYLOR AND CLARK COUNTIES...BUT IF THE 05.22Z/05.23Z RAP RUNS ARE
CORRECT...THE PRECIPITATION MAY BE DELAYED ENOUGH (14-15Z) THAT
THE BULK OF THE PRECIPITATION ENDS UP AS RAIN. WILL KEEP THE
ADVISORY IDEA AS A POSSIBILITY GOING FORWARD...THOUGH.
.LONG TERM...SATURDAY THROUGH WEDNESDAY
355 PM CST WED DEC 5 2012
ON SATURDAY...THE 05.12Z MODELS ARE IN GOOD AGREEMENT THAT WE WILL
SEE QUITE A BIT OF SUBSIDENCE IN THE WAKE OF THE SHORT WAVE. AS A
RESULT...TOOK OUT THE MENTION OF SNOW FOR THIS DAY.
FROM LATE SATURDAY NIGHT INTO MONDAY...THE MODELS CONTINUE TO
STRUGGLE WITH THIS TIME PERIOD. MUCH OF THIS HAS TO DEAL WHETHER
THERE WILL BE ANY PHASING OF THE NORTHERN AND SOUTHERN STREAM
SYSTEMS. BOTH THE GEM AND ECMWF SUGGEST THAT THESE WAVES WILL NOT
PHASE...AND THE AREA WILL SEE SOME SNOW AS AN INVERTED TROUGH
MOVES NORTHEAST ACROSS THE AREA. MEANWHILE THE OPERATIONAL GFS
CONTINUES TO SHOW THAT THESE TWO SYSTEMS WILL PHASE. THIS RESULT
IN A MUCH STRONGER AND FURTHER NORTHWEST TRACK. IF THIS SCENARIO
DOES OCCUR...THERE COULD BE A BAND OF HEAVY SNOW ACROSS THE AREA.
HOWEVER THE GFS ENSEMBLE FAMILY ALSO SHOW A WIDE VARIETY OF
SOLUTIONS. ONLY 3 OF 12 WOULD SUPPORT THE OPERATIONAL GFS.
MEANWHILE THE REMAINDER EITHER SHOW THAT THE THE SOUTHERN STREAM
SYSTEM WILL BE WELL TO OUR SOUTHEAST...AND WE EITHER GET A LIGHT
DUSTING FROM THE NORTHERN STREAM OR SNOW AT ALL. AS A
RESULT...THERE IS MUCH LOWER CONFIDENCE IN THIS TIME PERIOD THAN
ONE MIGHT EXPECT BY JUST LOOKING AT THE OPERATIONAL MODELS.
&&
.AVIATION...THROUGH 06Z FRIDAY
1047 PM CST WED DEC 5 2012
SOUTHEAST WINDS REMAINED STRONG DURING THE EVENING...ESPECIALLY AT
KRST...DUE TO A TIGHT PRESSURE GRADIENT BETWEEN HIGH PRESSURE
OVER LAKE HURON AND A COLD FRONT OVER EASTERN SOUTH DAKOTA. THESE
WINDS LOOK TO STAY NEARLY STEADY STATE THROUGH 12Z AS THE COLD
FRONT APPROACHES...WHILE ALOFT SOUTHWEST SPEEDS OF 50-55 KT AT
2000 FT ARE EXPECTED. THESE WINDS WILL ALSO MAINTAIN A FEED OF DRY
AIR IN AT THE LOW LEVELS OF THE TROPOSPHERE AHEAD OF THE FRONT.
AROUND 12Z...THE COLD FRONT SHOULD BE APPROACHING MINNEAPOLIS AND
ALBERTA LEA. A BAND OF RAIN STILL LOOKS TO DEVELOP IN THE 09-12Z
TIME PERIOD AHEAD OF THE FRONT...SHIFTING EAST INTO KRST AROUND
13Z AND POSSIBLY AFFECTING KLSE AROUND 15Z. THE APPROACH OF THE
FRONT WILL ALSO ALLOW BOTH THE WINDS AND LOW LEVEL WIND SHEAR TO
DIMINISH. FRONTAL PASSAGE SHOULD OCCUR AROUND 18Z AT KRST AND 21Z
AT KLSE. SUBSIDENCE ASSOCIATED WITH A DRY SLOT IN THE WAKE OF THE
FRONT IS EXPECTED TO CAUSE THE CLOUDS TO BREAK UP...ALONG WITH A
SHIFT OF WINDS TO THE WEST OR EVEN NORTHWEST WITH SPEEDS AROUND 10
KT. PLAN ON WINDS TO DIMINISH THURSDAY NIGHT AS HIGH PRESSURE
BUILDS IN FROM THE PLAINS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
355 PM CST WED DEC 5 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...BOYNE
AVIATION...AJ
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1002 PM MST FRI DEC 7 2012
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 144 PM MST FRI DEC 7 2012
LATEST SATELLITE IMAGERY DEPICTS AN UPPER LEVEL TROUGH AXIS
EXTENDING FROM SOUTHEASTERN COLORADO NORTHEAST INTO NORTHERN MINNESOTA.
BEHIND THE TROUGH AXIS RUC ANALYSIS PLACES A SHORT WAVE TROUGH OVER
THE NE/SD LINE. AT THE SURFACE A PRE-FRONTAL TROUGH WAS MOVING
SOUTHEAST THROUGH THE PLAINS. SUBSIDENCE BEHIND THE SHORT WAVE TROUGH
AND TROUGH AXIS HAS LEAD TO CLEARING SKIES BEHIND THE SURFACE
FEATURE.
LATE THIS EVENING A WEAK SHORT WAVE TROUGH WILL DEVELOP OVER EASTERN
COLORADO AND PROGRESS ACROSS THE WESTERN HALF OF THE TRI-STATE
AREA. SREF/NAM ISENTROPIC ANALYSIS INDICATES LIFT AHEAD OF THE
SHORT WAVE TROUGH AROUND 700MB WHERE POINT SOUNDINGS ALSO SATURATE.
THE DRAWBACK IS A DRY LAYER BELOW THIS WHICH WILL LIMIT HOW MUCH
SNOW WILL REACH THE GROUND. THE MCCOOK AND NORTON AREA HAD A
SIMILAR SETUP THIS MORNING...WITH THE MCCOOK AIRPORT REPORTING
DRIZZLE. WITH THIS IN MIND WILL PLACE A MENTION OF FLURRIES AHEAD
OF THE SHORT WAVE TROUGH. THE FLURRIES WILL GENERALLY MOVE FROM
SOUTHWEST TO NORTHEAST DURING THE NIGHT OVER THE WESTERN HALF OF THE
AREA.
SATURDAY THE SHORT WAVE TROUGH WILL CONTINUE TO MOVE ACROSS THE AREA
DURING THE MORNING. HAVE THE FLURRIES CHANGING TO DRIZZLE
DURING THE LATE MORNING AS SURFACE TEMPERATURES WARM INTO THE LOWER
30S. THE ISENTROPIC LIFT AHEAD OF THE TROUGH WILL EXIT THE AREA BY
EARLY AFTERNOON. SOUTH WINDS WILL BE BREEZY DURING THE AFTERNOON AS
25KT 850MB WINDS MIX TO THE GROUND AND THE SURFACE PRESSURE GRADIENT
TIGHTENS. THE BREEZY WINDS WILL HELP WARM TEMPERATURES AHEAD OF THE
NEXT COLD FRONT...WHICH WILL MOVE INTO THE AREA DURING THE MID TO
LATE AFTERNOON. LIFTING AND MOISTURE WILL BE BEST ALONG AND SHORTLY
BEHIND THE FRONT. HOWEVER MODELS SHOW A FAIRLY DEEP DRY LAYER AS
THE FRONT MOVES THROUGH...WHICH MAY LIMIT THE AMOUNT OF RAIN THAT
REACHES THE GROUND. MODELS SHOW RAPID PRESSURE RISE BEHIND THE COLD
FRONT...WHICH WILL CAUSE WINDS TO STRENGTHEN BEHIND THE FRONT.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 247 PM MST
FRI DEC 7 2012
THE COLD FRONT WILL CONTINUE TO PUSH ACROSS THE FORECAST AREA
SATURDAY NIGHT. THE FAVORED AREA OF PRECIPITATION WILL INITIALLY BE
ACROSS THE NORTHERN SECTIONS OF THE FORECAST AREA IN THE VICINITY
OF THE FRONT WITH LIGHT RAIN CHANGING QUICKLY OVER TO LIGHT SNOW
AROUND SUNSET. A SLIGHT CHANCE OF LIGHT SNOW WILL SPREAD ACROSS THE
FORECAST AREA WITH THE FRONT...WITH THE BEST CHANCE OF
PRECIPITATION REMAINING ALONG THE NORTHERN TIER OF COUNTIES WHERE
THE SYNOPTIC SCALE LIFT REMAINS GREATER AS A SERIES OF SHORT WAVES
SHEAR OUT ACROSS THE PLAINS AHEAD OF THE MAIN UPPER TROUGH. THE
POSSIBILITY OF PRECIPITATION DECREASES THROUGH THE REMAINDER OF
SATURDAY NIGHT AND SUNDAY MORNING...WITH LIGHT SNOW ENDING BY MID
DAY ON SUNDAY. WITH THE STEEP PRESSURE GRADIENT REMAINING OVER THE
CENTRAL HIGH PLAINS REGION...EXPECT NORTH WINDS OF 20-30 MPH WILL
BE COMMON DURING THE DAY ON SUNDAY.
THE PRIMARY DEEP UPPER TROUGH SWEEPS QUICKLY THROUGH THE REGION
SUNDAY NIGHT WITH A COLD AREA OF HIGH PRESSURE MOVING IN BEHIND
THE FRONT. OVERNIGHT LOW TEMPERATURES WILL DROP INTO THE SINGLE
DIGITS AS SKIES ALSO BEGIN TO CLEAR OUT AND WINDS SLACKEN SUNDAY
NIGHT.
A SERIES OF OPEN WAVES WILL MOVE THROUGH THE UPPER FLOW NEXT
WEEK. ALTHOUGH THE PATTERN REMAINS ACTIVE...NO ADDITIONAL
PRECIPITATION IS EXPECTED THROUGH NEXT WEEK. COLDER TEMPERATURES
WILL CONTINUE INTO THE BEGINNING OF NEXT WEEK WITH A GRADUAL
WARMING BRINGING TEMPERATURES BACK TO NEAR AVERAGE FOR THIS TIME
OF YEAR THROUGH THE MIDDLE AND END OF NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 958 PM MST FRI DEC 7 2012
VARIABLE AND CHANGING WINDS/CEILINGS EXPECTED THROUGH THE PERIOD.
AFTER STARTING OUT LIGHT AND VARIABLE...WINDS WILL SHIFT TO THE
SOUTH AND INCREASE/BECOME DURING THE MID AND LATE MORNING HOURS.
WINDS WILL DECREASE RIGHT BEFORE A STRONG COLD FRONT MOVES THROUGH
THE AREA IN THE 03Z TO 06Z TIME FRAME. STRONG AND GUSTY WINDS ARE
EXPECTED THEN. IT IS POSSIBLE THAT RIGHT BEHIND THE FRONT CEILINGS
WILL BECOME MVFR OR LOWER TO JUST ABOVE MVFR. ANY LOW CEILING OR
VERY LIGHT PRECIPITATION IS NOT EXPECTED TO LAST VERY LONG OR
CAUSE ANY SIGNIFICANT VISIBILITY RESTRICTION.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JTL
LONG TERM...LOCKHART
AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
452 AM EST SAT DEC 8 2012
.SYNOPSIS...
A SERIES OF LOW PRESSURE CENTERS MOVING NORTHEASTWARD ALONG A
STALLED FRONT WILL CONTINUE TO PROVIDE THE UPPER OHIO VALLEY WITH
MILD TEMPERATURES AND PERIODS OF RAIN INTO MONDAY. EXPECT A COOL
DOWN TO SEASONABLE TEMPERATURES TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
RECENT SURFACE AND RADAR DATA SHOW THE BATCH OF RAIN HAS BEGUN TO
EXIT EAST PAST THE MOUNTAINS. SURFACE WINDS HAVE SLIGHTLY
INCREASED TO 5 KTS...AND THIS HAS HELPED VISIBILITIES IN FOG
IMPROVE OVER MUCH OF THE UPPER OHIO VALLEY. SO ONLY CONTINUED
MENTION OF PATCHY FOG THROUGH DAYBREAK NORTH.
WITH RECENT RAP MODEL OUTPUT CONTINUING TO SHOW ANOTHER SURGE OF
RAIN MOVING ACROSS THE UPPER OHIO VALLEY DURING TODAY...HAVE CONTINUED
MENTION OF RAIN. HOWEVER ONCE THE LOW PRESSURE CENTER FROM OHIO
PASSES NORTHEASTWARD THROUGH LAKE ERIE MIDDAY...RAIN WILL DECREASE
IN COVERAGE WEST TO EAST THIS AFTERNOON...LEAVING DRY CONDITIONS
FOR MUCH OF TONIGHT.
PER BLEND OF RECENT GFS AND NAM MOS ALONG WITH GFS LAMP AND RAP
MODEL OUTPUT...FORECASTED TEMPERATURES TO CLIMB TO HIGHS THIS
AFTERNOON AT LEAST 15 DEGREES WARMER THAN NORMAL. POST SYSTEM
NORTHERLY WINDS TONIGHT WILL PROMOTE LOWS MORE THAN 10 DEGREES
COOLER THAN THIS OVERNIGHT BUT STILL ABOUT 10 DEGREES ABOVE
NORMAL.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY/...
CONCUR WITH RECENT SREF MODEL OUTPUT WITH DETAILS FROM NAM AND
WRF-NMM MODELS THAT THERE WILL BE ANOTHER SURGE OF RAIN SPREADING
NORTHEASTWARD ACROSS THE UPPER OHIO VALLEY DAYTIME SUNDAY AND
SUNDAY NIGHT. THIS RAIN SURGE WILL BE ASSOCIATED WITH A LOW
PRESSURE CENTER MOVING NORTHEASTWARD FROM MISSOURI.
ONCE THE LOW PRESSURE CENTER PASSES NORTHEASTWARD THROUGH LAKE
ERIE MONDAY MORNING...THE RAIN WILL TAPER TO SHOWERS. COLDER
POSTFRONTAL AIR WILL CAN CAUSE TEMPERATURES TO FALL MONDAY
AFTERNOON. LINGERING SHOWERS MONDAY NIGHT CAN TURN TO LIGHT SNOW
SHOWERS BEFORE ENDING LATE. TUESDAY SHOULD CONTINUE TO BE MAINLY
CLOUDY DUE TO ENSUING COLD POOL.
FORECASTED TEMPERATURES TO BE CONSIDERABLY WARMER THAN NORMAL
SUNDAY INTO MONDAY MORNING...THEN COOL DOWN TO SEASONABLE VALUES
MONDAY NIGHT AND TUESDAY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
GFSE/ECMWF AGREE THAT HIGH PRESSURE WILL BUILD OVER THE AREA FROM
THE SOUTHWEST TUESDAY NIGHT AND WEDNESDAY. THAT FEATURE...ALONG
WITH A DEEP LAYER OF DRY AIR...WILL KEEP THE FORECAST DRY THROUGH
FRIDAY.
TEMPS THROUGH THE MID-WEEK WILL BE NEAR SEASONAL VALUES IN
THE COOLER AIR MASS BEHIND THE FRONT. READINGS ARE EXPECTED TO
MODERATE TO AROUND 5 DEGREES ABOVE NORMAL BY THE END OF THE WEEK
AS FLOW ALOFT BECOMES MORE SOUTHWESTERLY.
&&
.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
RAIN AND FOG WILL PREVAIL TONIGHT AT ALL TERMINALS WITH IFR CONDITIONS.
WINDS WILL BE MAINLY FROM THE SOUTH/SOUTHEAST AT LESS THAN 5 KTS.
AS FRONTAL BOUNDARY SLOWLY PUSHES SOUTHEAST SATURDAY AFTERNOON...IFR
CEILINGS BEGINNING AT WESTERN TERMINALS WILL LIFT TO MVFR CONDITIONS
THROUGH THE EVENING.
.OUTLOOK.../SUNDAY THROUGH WEDNESDAY/...
NEXT LOW PRESSURE SYSTEM WILL CAUSE RESTRICTIONS THROUGH TUESDAY
BEFORE COLD FRONT MOVES OUT OF THE REGION AND VFR CONDITIONS FINALLY
RETURN.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
138 AM EST SAT DEC 8 2012
.SYNOPSIS...
A STATIONARY FRONT WILL BE THE FOCUS FOR PERIODIC RAIN ACROSS THE
UPPER OHIO VALLEY INTO MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
PER RECENT SURFACE AND RADAR DATA HAVE CONTINUED MENTION OF RAIN
AND PATCHY FOG ACROSS THE UPPER OHIO VALLEY UNTIL EARLY MORNING.
FORECASTED TEMPERATURES TO BE NEARLY STEADY THE REST OF TONIGHT.
BLEND OF RECENT RAP NAM AND WRF-NMM SHOW THAT HAS THE LOW
PRESSURE CENTER FROM INDIANA PASSES NORTHEASTWARD THROUGH
NORTHWESTERN PENNSYLVANIA DURING MIDDAY...RAIN WILL DECREASE IN
COVERAGE WEST TO EAST THIS AFTERNOON. CONCUR WITH CONSENSUS OF
SREF MODEL MEMBERS THAT THERE CAN EVEN BE A DRY BREAK EARLY
TONIGHT.
THEN EXPECT A SURGE OF RAIN TO SPREAD NORTHEASTWARD INTO THE UPPER
OHIO VALLEY LATE TONIGHT...AHEAD OF THE NEXT LOW PRESSURE CENTER
TRAVELING EASTWARD ALONG THE STATIONARY FRONT SITUATED NEAR THE
MASON-DIXON LINE.
PER BLEND OF RECENT GFS AND NAM MOS ALONG WITH GFS LAMP AND RAP
MODEL OUTPUT...FORECASTED TEMPERATURES TO CLIMB TO HIGHS THIS
AFTERNOON AT LEAST 15 DEGREES WARMER THAN NORMAL. POST SYSTEM
NORTHERLY WINDS TONIGHT WILL PROMOTE LOWS MORE THAN 10 DEGREES
COOLER THAN THIS OVERNIGHT BUT STILL ABOUT 10 DEGREES ABOVE
NORMAL.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
A SMALL BUBBLE OF HIGH PRESSURE IS FORECAST TO BUILD OVER THE
REGION FROM THE EASTERN GREAT LAKES SATURDAY NIGHT...RESULTING IN
A GENERALLY DRY FORECAST...WITH EXCEPTION FOR ISOLATED SHOWERS
WHICH MAY STILL BE POSSIBLE MAINLY ACROSS THE RIDGES.
BY SUNDAY...THE NEXT...AND STRONGER SHORTWAVE IS PROJECTED TO BRING
THE FRONT NORTHWARD AND SPREAD MORE RAIN ACROSS THE REGION FROM
SOUTH TO NORTH.
THEREAFTER...THE AREA WILL REMAIN IN THE WARM SECTOR OF A GREAT
LAKES LOW PRES SYSTEM WITH OCCASIONAL RAIN AND QUITE MILD
TEMPERATURES.
ON MONDAY...THAT SYSTEMS COLD FRONT WILL TRAVERSE THE REGION
ACCOMPANIED BY RAIN AND FALLING AFTERNOON TEMPERATURES.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
MODELS ARE IN GENL AGREEMENT IN DEPICTIONS OF COLD FRONT PUSHING
SOUTHEAST OF THE AREA MONDAY NIGHT...WITH COLD AIR ADVECTION
CONTINUING THROUGH TUESDAY. THE ECMWF IS SLIGHTLY SLOWER WITH THE
FRONT AND THE FORECAST IS A BLEND OF THE ECMWF WITH THE FASTER
GFS/NAM AT THE START.
AS COLDER AIR FILTERS IN BEHIND THE FRONT...THE GFS AND ECMWF
THICKNESS REDUCTION SUPPORTS SNOW SHOWERS BEFORE PRECIPITATION
COMES TO AN END EARLY ON TUESDAY.
GFSE/ECMWF ALSO AGREE THAT HIGH PRESSURE WILL BUILD OVER THE AREA
FROM THE SOUTHWEST TUESDAY NIGHT AND WEDNESDAY. THAT FEATURE...ALONG
WITH A DEEP LAYER OF DRY AIR...WILL KEEP THE FORECAST DRY THROUGH
FRIDAY. TEMPS THROUGH THE MID-WEEK WILL BE NEAR SEASONAL VALUES IN
THE COOLER AIR MASS BEHIND THE FRONT. READINGS ARE EXPECTED TO
MODERATE TO AROUND 5 DEGREES ABOVE NORMAL BY THE END OF THE WEEK
AS FLOW ALOFT BECOMES MORE SOUTHWESTERLY.
&&
.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
RAIN AND FOG WILL PREVAIL TONIGHT AT ALL TERMINALS WITH IFR CONDITIONS.
WINDS WILL BE MAINLY FROM THE SOUTH/SOUTHEAST AT LESS THAN 5 KTS.
AS FRONTAL BOUNDARY SLOWLY PUSHES SOUTHEAST SATURDAY AFTERNOON...IFR
CEILINGS BEGINNING AT WESTERN TERMINALS WILL LIFT TO MVFR CONDITIONS
THROUGH THE EVENING.
.OUTLOOK.../SUNDAY THROUGH WEDNESDAY/...
NEXT LOW PRESSURE SYSTEM WILL CAUSE RESTRICTIONS THROUGH TUESDAY
BEFORE COLD FRONT MOVES OUT OF THE REGION AND VFR CONDITIONS FINALLY
RETURN.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
349 AM EST SAT DEC 8 2012
.SYNOPSIS...
WARMING SOUTHWEST FLOW WILL BE FEATURED ACROSS THE REGION THIS
WEEKEND. SHOWER CHANCES ARE EXPECTED TO INCREASE BY MONDAY OUT AHEAD
OF AN APPROACHING COLD FRONT. HIGH PRESSURE MOVE BACKS IN FOR MID
WEEK WITH COOLER TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM SAT...DENSE FOG BEING OBSERVED ACROSS PARTS OF THE
CWFA...MAINLY THE NC FOOTHILLS...BUT ALSO AT SOME SITES IN THE LOWER
SC PIEDMONT. CONDITIONS HAVE BEEN SOMEWHAT STABLE FOR A COUPLE OF
HOURS NOW AND SOME SITES HAVE ALREADY SEEN DENSE FOG DEVELOP AND
THEN THIN OUT. THIS IS BELIEVED TO HAVE HAPPENED DUE TO SETTLING OF
FOG DROPLETS AS THE TOP OF THE FOG LAYER IS KEPT WARMER BY HIGHER
CLOUDS PASSING OVERHEAD. SOME DRYING WAS INDICATED ON RAP LOW LEVEL
RH AND PROG SOUNDINGS AND THIS COULD HAVE ALSO CONTRIBUTED.
NONETHELESS...A DENSE FOG ADVISORY HAS BEEN ISSUED FOR THE NC
FOOTHILLS AREA WHERE VISIBILITIES HAVE REMAINED LOW IN A CONTIGUOUS
AREA. RAPID IMPROVEMENT IS EXPECTED AFTER SUNRISE.
WEAK HIGH PRESSURE REMAINS OVER THE SOUTH ATLANTIC COAST THROUGH THE
PERIOD...MAINTAINING SOUTHWESTERLY LOW TO MID LEVEL FLOW ACROSS THE
CWFA. MOISTURE IN TERMS OF 850MB DEWPOINTS AND 850-700MB RH
INCREASES AS A RESULT. ISENTROPIC VERTICAL MOTION IS GENERALLY
NEUTRAL WITH ONLY GRADUAL INCREASES IN 850MB TEMPS NOTED. THE FLOW
IS SOMEWHAT UPSLOPING BUT THE SOUTHWEST ORIENTATION IS ONLY LIKELY
TO PRODUCE POPS OVER OUR SOUTHWEST MTNS. THIS LOOKS TO BE THE BEST
AVAILABLE FORCING DURING THE DAY SATURDAY. THE GFS POP EVOLUTION
SEEMED TO BEST REFLECT THAT SO I BASED TRENDS ON IT DURING THAT
TIME. HIGHEST POPS LOOK TO BE AFTER 00Z SUN AS POCKET OF MIDLEVEL Q
VECTOR CONVERGENCE MOVES NORTHWARD ACROSS THE CWFA WHILE MOISTURE
CONTINUES TO STREAM IN.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 245 AM SATURDAY...THE MAIN FOCUS FOR THE SHORT RANGE WILL BE
THE PASSAGE OF A COLD FRONT LATE IN THE PERIOD. FOR SUNDAY AND
SUNDAY NIGHT...WE WILL CONTINUE TO HAVE TO DEAL WITH THE UNCERTAIN
BEGINNINGS OF PRE-FRONTAL SHOWER ACTIVITY. LOW LEVEL FORCING AND
MOISTURE LOOK ADEQUATE AS THEY HAVE FOR THE LAST FEW MODEL RUNS...
AND THE GFS/NAM SHOW A WEAK UPPER WAVE MOVING OVERHEAD IN THE
STRENGTHENING SW FLOW ALOFT. THAT SHOULD BE ENOUGH TO JUSTIFY
CARRYING A LOW END 20-30 PRECIP CHANCE TO ACCOUNT FOR SOME SCATTERED
LIGHT SHOWER ACTIVITY AND TO MATCH THE FCST FROM NEIGHBORING
OFFICES. DO NOT EXPECT THIS TO AMOUNT TO MUCH. TEMPS SUNDAY ARE
STILL A BIT PROBLEMATIC...ALTHO WE ARE LESS LIKELY TO BE BOTHERED
WITH ANY LINGERING COOL POOL AND WARM ADVECTION SHOULD ALLOW FOR
U60S/L70S OUTSIDE THE MTNS IN SPITE OF CLOUD COVER. EXPECT SUNDAY
NIGHT TO BE QUITE MILD FOR DECEMBER.
WHICH BRINGS US TO MONDAY. THERE HAS BEEN DISAGREEMENT AMONG MODEL
SOLUTIONS AS TO THE TIMING OF THE FRONTAL PASSAGE EVER SINCE THIS
EVENT CAME ONTO THE HORIZON...BUT NOW THE OPERATIONAL RUNS SEEM TO
BE IN BETTER AGREEMENT WITH A FOCUS ON LATE MONDAY OR EARLY TUESDAY
MORNING. THE MODELS SHOW AN EXCELLENT SWATH OF FORCING AND DEEP
MOISTURE APPROACHING FROM THE WEST EARLY MONDAY. THE PROBLEM IS THAT
THIS THING MAY BE WEAKENING THE WHOLE WAY AS IT MOVES IN...AS THE
MAIN SHORT WAVE LIFTS PAST TO THE NW AND THE BEST UPPER DIVERGENCE
DOES THE SAME. LOW LEVEL FORCING SHOULD CARRY A PRECIP BAND INTO THE
NC MTNS BY THE AFTERNOON...SO A LIKELY POP IS STILL WARRANTED AS IN
THE RECENT MOSGUIDE. HAVE EXTENDED THE LOW END LIKELY EAST ACROSS
THE FOOTHILLS AND PIEDMONT LATE IN THE DAY ON THE STRENGTH OF THE
LOW LEVEL FORCING. THE BIG QUESTION IS THE SEVERE WEATHER POTENTIAL.
CONFIDENCE IS GREATER IN THE POTENTIAL FOR STRONG SHEAR AS A LOW
LEVEL JET MOVES NE AHEAD OF THE FRONT ON MONDAY. IF THE GFS IS
CORRECT...THE PIEDMONT OF THE CAROLINAS WILL SEE ENOUGH BUOYANCY
THAT WE WILL HAVE TO WORRY ABOUT WIND DAMAGE AND PERHAPS AN ISOLATED
BRIEF TORNADO IF THE CONVECTIVE MODE IS LINEAR. THAT REMAINS A BIG
IF. THE NAM LIMITS THE POTENTIAL TO NE GEORGIA AND UPSTATE SC S AND
E OF I-85. THE ECMWF IS NOT IMPRESSED. WILL NOT TALK THIS UP IN THE
HWO JUST YET...BUT WILL KEEP IT SIMMERING ON A BACK BURNER. WILL
HOWEVER CONTINUE TO MENTION SOME THUNDER MONDAY AFTERNOON AND
EVENING OVER THE EASTERN ZONES. PRECIP CHANCES GRADUALLY DIMINISH
MONDAY NIGHT AS THE FRONT WEAKENS E OF THE FCST AREA.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AT 230 AM EST SATURDAY...A BROAD AND FAIRLY DEEP TROUGH WILL BE OVER
THE CENTER OF NORTH AMERICA ON TUESDAY. THIS TROUGH DEAMPLIFIES ON
WEDNESDAY...WHILE ANOTHER TROUGH AMPLIFIES ALONG THE WEST COAST. A
FAST MOVING SHORTWAVE OVER TEXAS WEDNESDAY AFTERNOON WILL REACH OUR
REGION THURSDAY WITH SURFACE LOW PRESSURE GENERATED IN THE GULF
BEING PULLED ACROSS FLORIDA TO THE CAROLINA COAST. THE GFS IS A BIT
FASTER WITH THIS SHORTWAVE THAN THE ECMWF.
WITH THE FASTER PROGRESSION OF THE GFS...ALL PRECIP HAD ENDED OVER
THE WESTERN CAROLINAS BY 12Z TUESDAY. HIGH PRESSURE CENTERED OVER
THE TENNESSEE AND OHIO VALLEYS THROUGH MID WEEK PROVIDING DRY
WEATHER FOR OUR REGION AS THE FRONT LINGERS OVER FLORIDA. THE
CURRENT GFS RUN HAS THE 500MB SHORTWAVE REACHING GEORGIA AT 12Z
THURSDAY WITH SOME RAIN SPREADING OVER NE GA AND THE UPSTATE. ALL
PRECIP IS WELL EAST OF I-77 BY 00Z FRIDAY. THE GFS HAS THE CHARLOTTE
AREA GETTING NEAR A HALF INCH OF RAIN AND EVEN MORE NEAR MARSHVILLE.
SURFACE HIGH CENTERED OVER THE CAROLINAS AND VIRGINIA FOR FRIDAY ON
THE GFS. THE NEXT SYSTEM WILL BE CROSSING TENNESSEE BY 12Z SATURDAY.
THE NEW ECMWF HAS THE COLD FRONT CROSSING OUR AREA AT 12Z TUESDAY
WITH THE RAIN GRADUALLY ENDING EAST OF CHARLOTTE AROUND SUNSET. THE
HIGH IS ALIGNED ROUGHLY THE SAME ON WEDNESDAY AS ON THE GFS WITH THE
FRONT LINGERING ACROSS FLORIDA. THE SHARP 500MB SHORTWAVE WILL BE
OVER THE MISSISSIPPI RIVER 00Z THURSDAY AND OVER WESTERN GEORGIA AT
12Z THURSDAY AND DEEPER THAN THE GFS AT THAT TIME. THE BIG
DIFFERENCE IN THE PRECIP SHIELD IS THAT LITTLE IF ANY PRECIP REACHES
OUR PIEDMONT AS THE SHORTWAVE PASSES ON THURSDAY ACCORDING TO THE
ECMWF. THE NEXT SYSTEM WILL BE CROSSING TENNESSEE BY 12Z SATURDAY AS
WELL BUT SOME PRECIP REACHING THE WESTERN MOUNTAINS EARLY SATURDAY.
TEMPERATURES NEAR NORMAL THROUGH THE MEDIUM RANGE.
&&
.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
09Z KCLT UPDATE...CURRENT CIG LIKELY TO PERSIST TO A COUPLE OF HOURS
AFTER SUNRISE. LATEST MESOSCALE MODEL SOUNDINGS INDICATE THE
SATURATED LAYER REMAINING UNCHANGED IN THICKNESS. WEAK SOUTHWESTERLY
FLOW COULD ADVECT IN SOMEWHAT DRIER AIR FROM THE SOUTHWEST /PER SFC
OBS/ BUT THE FLOW WILL BE SLOW TO GET GOING GIVEN THE LOW CIGS AND
SLOW HEATING. HAVE PUSHED BACK THE DISSIPATION OF THE CIG TO 15Z AND
IF ANYTHING THIS WILL PROBABLY HAVE TO BE DELAYED FURTHER...BUT WILL
MONITOR SKY COVER TRENDS AROUND THE REGION AND TRY TO INCREASE
CONFIDENCE IN DISSIPATION FOR THE 12Z ISSUANCE.
AT KCLT AND ELSEWHERE...AVIATION FORECAST CONTINUES TO BE QUITE
TRICKY. IFR TO LIFR CIGS OBSERVED ATTM ACROSS MUCH OF THE FCST
AREA...PRIMARILY OVER THE ERN PIEDMONT. 1000-850MB LAYER DRIES A BIT
OVER THAT AREA OVER THE NEXT FEW HOURS WHICH COULD EITHER HELP
EVAPORATE FOG...OR PROMOTE CLEARING ABOVE THE FOG LAYER WHICH WOULD
ALLOW IT TO BECOME MORE DENSE. CIRRUS MOVING ACROSS THE REGION WILL
LIMIT CLOUD TOP COOLING WHICH IS ANOTHER LIMITING FACTOR FOR FOG/LOW
STRATUS DEVELOPMENT. AN EXAMINATION OF MODEL SOUNDINGS SHOWS THE SFC
SATURATED LAYER BECOMING THINNER WITH TIME TONIGHT. THIS DOES NOT
NECESSARILY MEAN OPERATIONAL CONDITIONS WILL IMPROVE AT AFFECTED
AIRPORTS BUT IT IMPLIES LESS PERSISTENT RESTRICTIONS. HAVE GENERALLY
MAINTAINED PRESENT CONDITIONS UNTIL JUST AFTER SUNRISE...WITH SOME
SLIGHT IMPROVEMENT LATE AS THE DRYING OCCURS ALOFT. ONCE THE
OVERNIGHT FOG/STRATUS LIFT IN THE MORNING SOME VFR CLOUDS WILL
REMAIN IN PLACE THROUGH THE DAY. GUIDANCE HINTS AT SOME
REDEVELOPMENT OF RESTRICTIONS NEAR THE END OF THE PERIOD...AFTER 00Z
SUN...BUT CONFIDENCE CURRENTLY LOW SO DO NOT WANT TO INCLUDE IN TAFS
YET.
OUTLOOK...VFR CONDITIONS ARE EXPECTED OVERALL THRU THE WEEKEND...BUT
PATCHY FOG AND STRATUS WILL BE POSSIBLE BOTH SUNDAY AND MONDAY
MORNINGS. A STRONG COLD FRONT WILL CROSS THE REGION MONDAY OR MONDAY
NIGHT...ACCOMPANIED BY SHOWERS AND THUNDERSTORMS ALONG WITH GUSTY
WINDS.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...DENSE FOG ADVISORY UNTIL 8 AM EST THIS MORNING FOR NCZ035-036-
056-068-069-501>510.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...WIMBERLEY
SHORT TERM...PM
LONG TERM...DEO
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
319 AM EST SAT DEC 8 2012
.SYNOPSIS...
WARMING SOUTHWEST FLOW WILL BE FEATURED ACROSS THE REGION THIS
WEEKEND. SHOWER CHANCES ARE EXPECTED TO INCREASE BY MONDAY OUT AHEAD
OF AN APPROACHING COLD FRONT. HIGH PRESSURE MOVE BACKS IN FOR MID
WEEK WITH COOLER TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM SAT...DENSE FOG BEING OBSERVED ACROSS PARTS OF THE
CWFA...MAINLY THE NC FOOTHILLS...BUT ALSO AT SOME SITES IN THE LOWER
SC PIEDMONT. CONDITIONS HAVE BEEN SOMEWHAT STABLE FOR A COUPLE OF
HOURS NOW AND SOME SITES HAVE ALREADY SEEN DENSE FOG DEVELOP AND
THEN THIN OUT. THIS IS BELIEVED TO HAVE HAPPENED DUE TO SETTLING OF
FOG DROPLETS AS THE TOP OF THE FOG LAYER IS KEPT WARMER BY HIGHER
CLOUDS PASSING OVERHEAD. SOME DRYING WAS INDICATED ON RAP LOW LEVEL
RH AND PROG SOUNDINGS AND THIS COULD HAVE ALSO CONTRIBUTED.
NONETHELESS...A DENSE FOG ADVISORY HAS BEEN ISSUED FOR THE NC
FOOTHILLS AREA WHERE VISIBILITIES HAVE REMAINED LOW IN A CONTIGUOUS
AREA. RAPID IMPROVEMENT IS EXPECTED AFTER SUNRISE.
WEAK HIGH PRESSURE REMAINS OVER THE SOUTH ATLANTIC COAST THROUGH THE
PERIOD...MAINTAINING SOUTHWESTERLY LOW TO MID LEVEL FLOW ACROSS THE
CWFA. MOISTURE IN TERMS OF 850MB DEWPOINTS AND 850-700MB RH
INCREASES AS A RESULT. ISENTROPIC VERTICAL MOTION IS GENERALLY
NEUTRAL WITH ONLY GRADUAL INCREASES IN 850MB TEMPS NOTED. THE FLOW
IS SOMEWHAT UPSLOPING BUT THE SOUTHWEST ORIENTATION IS ONLY LIKELY
TO PRODUCE POPS OVER OUR SOUTHWEST MTNS. THIS LOOKS TO BE THE BEST
AVAILABLE FORCING DURING THE DAY SATURDAY. THE GFS POP EVOLUTION
SEEMED TO BEST REFLECT THAT SO I BASED TRENDS ON IT DURING THAT
TIME. HIGHEST POPS LOOK TO BE AFTER 00Z SUN AS POCKET OF MIDLEVEL Q
VECTOR CONVERGENCE MOVES NORTHWARD ACROSS THE CWFA WHILE MOISTURE
CONTINUES TO STREAM IN.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 245 AM SATURDAY...THE MAIN FOCUS FOR THE SHORT RANGE WILL BE
THE PASSAGE OF A COLD FRONT LATE IN THE PERIOD. FOR SUNDAY AND
SUNDAY NIGHT...WE WILL CONTINUE TO HAVE TO DEAL WITH THE UNCERTAIN
BEGINNINGS OF PRE-FRONTAL SHOWER ACTIVITY. LOW LEVEL FORCING AND
MOISTURE LOOK ADEQUATE AS THEY HAVE FOR THE LAST FEW MODEL RUNS...
AND THE GFS/NAM SHOW A WEAK UPPER WAVE MOVING OVERHEAD IN THE
STRENGTHENING SW FLOW ALOFT. THAT SHOULD BE ENOUGH TO JUSTIFY
CARRYING A LOW END 20-30 PRECIP CHANCE TO ACCOUNT FOR SOME SCATTERED
LIGHT SHOWER ACTIVITY AND TO MATCH THE FCST FROM NEIGHBORING
OFFICES. DO NOT EXPECT THIS TO AMOUNT TO MUCH. TEMPS SUNDAY ARE
STILL A BIT PROBLEMATIC...ALTHO WE ARE LESS LIKELY TO BE BOTHERED
WITH ANY LINGERING COOL POOL AND WARM ADVECTION SHOULD ALLOW FOR
U60S/L70S OUTSIDE THE MTNS IN SPITE OF CLOUD COVER. EXPECT SUNDAY
NIGHT TO BE QUITE MILD FOR DECEMBER.
WHICH BRINGS US TO MONDAY. THERE HAS BEEN DISAGREEMENT AMONG MODEL
SOLUTIONS AS TO THE TIMING OF THE FRONTAL PASSAGE EVER SINCE THIS
EVENT CAME ONTO THE HORIZON...BUT NOW THE OPERATIONAL RUNS SEEM TO
BE IN BETTER AGREEMENT WITH A FOCUS ON LATE MONDAY OR EARLY TUESDAY
MORNING. THE MODELS SHOW AN EXCELLENT SWATH OF FORCING AND DEEP
MOISTURE APPROACHING FROM THE WEST EARLY MONDAY. THE PROBLEM IS THAT
THIS THING MAY BE WEAKENING THE WHOLE WAY AS IT MOVES IN...AS THE
MAIN SHORT WAVE LIFTS PAST TO THE NW AND THE BEST UPPER DIVERGENCE
DOES THE SAME. LOW LEVEL FORCING SHOULD CARRY A PRECIP BAND INTO THE
NC MTNS BY THE AFTERNOON...SO A LIKELY POP IS STILL WARRANTED AS IN
THE RECENT MOSGUIDE. HAVE EXTENDED THE LOW END LIKELY EAST ACROSS
THE FOOTHILLS AND PIEDMONT LATE IN THE DAY ON THE STRENGTH OF THE
LOW LEVEL FORCING. THE BIG QUESTION IS THE SEVERE WEATHER POTENTIAL.
CONFIDENCE IS GREATER IN THE POTENTIAL FOR STRONG SHEAR AS A LOW
LEVEL JET MOVES NE AHEAD OF THE FRONT ON MONDAY. IF THE GFS IS
CORRECT...THE PIEDMONT OF THE CAROLINAS WILL SEE ENOUGH BUOYANCY
THAT WE WILL HAVE TO WORRY ABOUT WIND DAMAGE AND PERHAPS AN ISOLATED
BRIEF TORNADO IF THE CONVECTIVE MODE IS LINEAR. THAT REMAINS A BIG
IF. THE NAM LIMITS THE POTENTIAL TO NE GEORGIA AND UPSTATE SC S AND
E OF I-85. THE ECMWF IS NOT IMPRESSED. WILL NOT TALK THIS UP IN THE
HWO JUST YET...BUT WILL KEEP IT SIMMERING ON A BACK BURNER. WILL
HOWEVER CONTINUE TO MENTION SOME THUNDER MONDAY AFTERNOON AND
EVENING OVER THE EASTERN ZONES. PRECIP CHANCES GRADUALLY DIMINISH
MONDAY NIGHT AS THE FRONT WEAKENS E OF THE FCST AREA.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AT 230 AM EST SATURDAY...A BROAD AND FAIRLY DEEP TROUGH WILL BE OVER
THE CENTER OF NORTH AMERICA ON TUESDAY. THIS TROUGH DEAMPLIFIES ON
WEDNESDAY...WHILE ANOTHER TROUGH AMPLIFIES ALONG THE WEST COAST. A
FAST MOVING SHORTWAVE OVER TEXAS WEDNESDAY AFTERNOON WILL REACH OUR
REGION THURSDAY WITH SURFACE LOW PRESSURE GENERATED IN THE GULF
BEING PULLED ACROSS FLORIDA TO THE CAROLINA COAST. THE GFS IS A BIT
FASTER WITH THIS SHORTWAVE THAN THE ECMWF.
WITH THE FASTER PROGRESSION OF THE GFS...ALL PRECIP HAD ENDED OVER
THE WESTERN CAROLINAS BY 12Z TUESDAY. HIGH PRESSURE CENTERED OVER
THE TENNESSEE AND OHIO VALLEYS THROUGH MID WEEK PROVIDING DRY
WEATHER FOR OUR REGION AS THE FRONT LINGERS OVER FLORIDA. THE
CURRENT GFS RUN HAS THE 500MB SHORTWAVE REACHING GEORGIA AT 12Z
THURSDAY WITH SOME RAIN SPREADING OVER NE GA AND THE UPSTATE. ALL
PRECIP IS WELL EAST OF I-77 BY 00Z FRIDAY. THE GFS HAS THE CHARLOTTE
AREA GETTING NEAR A HALF INCH OF RAIN AND EVEN MORE NEAR MARSHVILLE.
SURFACE HIGH CENTERED OVER THE CAROLINAS AND VIRGINIA FOR FRIDAY ON
THE GFS. THE NEXT SYSTEM WILL BE CROSSING TENNESSEE BY 12Z SATURDAY.
THE NEW ECMWF HAS THE COLD FRONT CROSSING OUR AREA AT 12Z TUESDAY
WITH THE RAIN GRADUALLY ENDING EAST OF CHARLOTTE AROUND SUNSET. THE
HIGH IS ALIGNED ROUGHLY THE SAME ON WEDNESDAY AS ON THE GFS WITH THE
FRONT LINGERING ACROSS FLORIDA. THE SHARP 500MB SHORTWAVE WILL BE
OVER THE MISSISSIPPI RIVER 00Z THURSDAY AND OVER WESTERN GEORGIA AT
12Z THURSDAY AND DEEPER THAN THE GFS AT THAT TIME. THE BIG
DIFFERENCE IN THE PRECIP SHIELD IS THAT LITTLE IF ANY PRECIP REACHES
OUR PIEDMONT AS THE SHORTWAVE PASSES ON THURSDAY ACCORDING TO THE
ECMWF. THE NEXT SYSTEM WILL BE CROSSING TENNESSEE BY 12Z SATURDAY AS
WELL BUT SOME PRECIP REACHING THE WESTERN MOUNTAINS EARLY SATURDAY.
TEMPERATURES NEAR NORMAL THROUGH THE MEDIUM RANGE.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT AND ELSEWHERE...AVIATION FORECAST CONTINUES TO BE QUITE
TRICKY. IFR TO LIFR CIGS OBSERVED ATTM ACROSS MUCH OF THE FCST
AREA...PRIMARILY OVER THE ERN PIEDMONT. 1000-850MB LAYER DRIES A BIT
OVER THAT AREA OVER THE NEXT FEW HOURS WHICH COULD EITHER HELP
EVAPORATE FOG...OR PROMOTE CLEARING ABOVE THE FOG LAYER WHICH WOULD
ALLOW IT TO BECOME MORE DENSE. CIRRUS MOVING ACROSS THE REGION WILL
LIMIT CLOUD TOP COOLING WHICH IS ANOTHER LIMITING FACTOR FOR FOG/LOW
STRATUS DEVELOPMENT. AN EXAMINATION OF MODEL SOUNDINGS SHOWS THE SFC
SATURATED LAYER BECOMING THINNER WITH TIME TONIGHT. THIS DOES NOT
NECESSARILY MEAN OPERATIONAL CONDITIONS WILL IMPROVE AT AFFECTED
AIRPORTS BUT IT IMPLIES LESS PERSISTENT RESTRICTIONS. HAVE GENERALLY
MAINTAINED PRESENT CONDITIONS UNTIL JUST AFTER SUNRISE...WITH SOME
SLIGHT IMPROVEMENT LATE AS THE DRYING OCCURS ALOFT. ONCE THE
OVERNIGHT FOG/STRATUS LIFT IN THE MORNING SOME VFR CLOUDS WILL
REMAIN IN PLACE THROUGH THE DAY. GUIDANCE HINTS AT SOME
REDEVELOPMENT OF RESTRICTIONS NEAR THE END OF THE PERIOD...AFTER 00Z
SUN...BUT CONFIDENCE CURRENTLY LOW SO DO NOT WANT TO INCLUDE IN TAFS
YET.
OUTLOOK...VFR CONDITIONS ARE EXPECTED OVERALL THRU THE WEEKEND...BUT
PATCHY FOG AND STRATUS WILL BE POSSIBLE BOTH SUNDAY AND MONDAY
MORNINGS. A STRONG COLD FRONT WILL CROSS THE REGION MONDAY OR MONDAY
NIGHT...ACCOMPANIED BY SHOWERS AND THUNDERSTORMS ALONG WITH GUSTY
WINDS.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...DENSE FOG ADVISORY UNTIL 8 AM EST THIS MORNING FOR NCZ035-036-
056-068-069-501>510.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...WIMBERLEY
SHORT TERM...PM
LONG TERM...DEO
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1035 PM CST FRI DEC 7 2012
.DISCUSSION.../ISSUED AT 85 PM CST/
ACTIVE FORECAST IN THE SHORT TERM. WENT AHEAD AND ALLOWED THE WINTER
WEATHER ADVISORY EXPIRE ACROSS THE AREA WITH ONLY MINOR ADDITIONAL
ACCUMULATIONS EXPECTED THROUGH THE EVENING. ATMOSPHERE IS EXPECTED
TO GRADUALLY DRY FROM ALOFT RESULTING IN DENDRITIC LAYER BEING CUT
OFF BRINGING AN END TO THE SNOW. LOW LEVEL SATURATION IS EXPECTED TO
REMAIN ACROSS THE AREA AND FOG HAS STARTED TO DEVELOP IN THE
STAGNANT AIR IN CENTRAL SOUTH DAKOTA. ADDED PATCHY FOG THIS EVENING
ACROSS THE WESTERN CWA THIS EVENING...BUT AS SOUTHERLY FLOW STARTS
TO INCREASE EARLY SATURDAY MORNING...THIS MAY LIMIT THE AREAL
COVERAGE WEST OF THE JAMES. FURTHER TO THE EAST...MUCH GREATER
POTENTIAL FOR FOG AS STRATUS BUILDS DOWN FROM ALOFT IN LIGHT
EASTERLY FLOW. RAP HAS DEVELOPED FAIRLY LARGE AREA ALONG AND EAST OF
I-29 OF FOG...AND MAY HAVE TO INCREASE WORDING AND NIGHT CREW MAY
NEED TO CONSIDER DENSE FOG ADVISORY. UPDATE POSTED.
&&
.AVIATION.../FOR THE 06Z TAF ISSUANCE/
WIDESPREAD IFR TO MVFR CEILINGS AND VISIBILITIES WILL PERSIST ACROSS
THE REGION THROUGH 06Z SUNDAY. SNOW WILL SPREAD IN FROM THE WEST
SATURDAY AFTERNOON AND EVENING AHEAD OF A LOW PRESSURE SYSTEM. THE
BEST CHANCE FOR SNOW ALONG WITH IFR CONDITIONS WILL BE NORTH OF 90
SATURDAY AFTERNOON AND EVENING.
&&
.PREV DISCUSSION.../ISSUED AT 333 PM CST/
SHORT WAVE ENERGY...WELL DELINEATED BY THE MID AND UPPER QG FORCING
MOVING ACROSS OUR NORTHERN ZONES...WILL EXIT OUR FORECAST AREA THIS
EVENING. LIGHT SNOW WILL LINGER THIS EVENING THROUGHOUT OUR EASTERN
ZONES AS THIS WAVE EXISTS. HOWEVER THE MESOSCALE DYNAMICS HAVE
LARGELY DISSIPATED. THEREFORE ONLY BROAD LIFT REMAINS...AND AN
ATMOSPHERE WHICH IS DRYING OUT ALOFT. THE WILD CARD TONIGHT IS CLOUD
COVER. MODEL HUMIDITY TIME SECTIONS STRONGLY SUGGEST THAT STRATUS
WILL LINGER IN OUR FORECAST AREA. AND IN AREAS WHERE IT WOULD HAPPEN
TO CLEAR OUT SOMEWHAT THIS EVENING...THE STRATUS IS LIKELY TO OOZE
BACK DOWN FROM THE NORTH. THEREFORE KEPT SKY COVER EITHER CLOUDY OR
MOSTLY CLOUDY WHICH SHOULD HOLD THE LOWS UP RELATIVELY SPEAKING. IF
PARTS OF THE FORECAST AREA WOULD HAPPEN TO CLEAR OUT...THEN LOWS
WILL CERTAINLY BE COLDER THAN FORECAST...ESPECIALLY OVER AREAS OF
NEW SNOW COVER. SOMETHING TO WATCH FOR. /MJF
RELATIVELY CONSISTENT FORECAST FROM THE MODELS FOR TOMORROW LEADS TO
SLIGHTLY ABOVE NORMAL CONFIDENCE. A WARM FRONT IN THE 800-650MB
LAYER WILL MOVE INTO THE AREA LATE SATURDAY MORNING...THEN MOVE INTO
THE EASTERN CWA BY TOMORROW EVENING. WHILE INSTABILITY IS NOT
IMPRESSIVE...THERE APPEARS TO BE ENOUGH TO SUPPORT A RELATIVELY FAST
MOVING BAND OF SNOWFALL DEVELOPMENT AS IT PASSES. EXPECT ABOUT AN
INCH OF POTENTIAL AS IT PASSES. WARMER AIR WILL SURGE NORTHWARD
DURING THE DAY AS LOW PRESSURE WRAPS UP TO THE NORTH AND WEST SO
WILL AIM FOR NEAR 40 ALONG THE MISSOURI RIVER VALLEY WITH LOWER 30S
IN THE FAR NORTHERN CWA. WITH THIS WARMER AIR SOME LIGHT RAIN WILL
BE POSSIBLE IN PARTS OF NORTHWEST IOWA BUT OVERALL THE MODELS ARE A
LITTLE COLDER THAN YESTERDAY WHICH SUPPORTS MORE SNOW VERSUS RAIN.
SATURDAY NIGHT INTO SUNDAY WILL SEE AN ARCTIC AIR MASS SURGE SOUTH
BEHIND THE EXITING LOW PRESSURE. UPPER LEVEL SUPPORT AS WELL AS A
LITTLE WEAK THETA E ADVECTION AND MID LEVEL FRONTAL FORCING WILL
ALLOW FOR THE CONTINUED THREAT FOR LIGHT SNOW SATURDAY NIGHT INTO
SUNDAY MORNING...MAINLY IN THE EASTERN CWA. AMOUNTS WILL BE LIMITED
SO NOT EXPECTING ANY HEADLINES AT THIS TIME. THE ONLY HEADLINER
POTENTIAL WILL BE WIND ADVISORY AS A STRONG PRESSURE GRADIENT AND 40
KNOT 925MB WIND COMBINE TO BRING THE POTENTIAL FOR 30 TO 40 MPH
WINDS ON SUNDAY. WHEN COMBINED WITH THE VERY COLD TEMPERATURES WIND
CHILLS OF ZERO TO TEN BELOW WILL BE LIKELY.
CLEARING SKIES AND A WEAK SHORT LIVED RIDGE OF HIGH PRESSURE WILL
MOVE THROUGH ON SUNDAY NIGHT...WITH SOUTHERLY FLOW DEVELOPING DURING
THE DAY MONDAY. LOWS AROUND ZERO MUCH OF THE AREA WITH 5 TO 10
ABOVE IN LOCATIONS WITH LITTLE OR NO SNOW COVER. HIGHS ON MONDAY
WILL MAINLY BE IN THE 20S SO A LITTLE BIT IN THE COLD SIDE.
IN THE LATTER PERIODS(TUE/FRI)...WEST NORTHWEST FLOW ALOFT WILL
GRADUALLY TRANSITION TO SOUTHWEST FLOW ALOFT. THIS WILL KEEP
TEMPERATURES AT OR BELOW NORMAL THROUGH THE PERIOD WITH LITTLE IN
THE WAY OF PRECIPITATION CHANCES. AT THIS TIME IT APPEARS THAT A JET
STREAK WILL MOVE THROUGH THE REGION BRINGING A SLIGHT WARM UP
TUESDAY INTO WEDNESDAY THEN COLDER AIR WILL AGAIN FILTER SOUTHWARD.
GENERALLY HIGHS IN THE 30S TUESDAY AND WEDNESDAY...A FEW 40S SOUTH
ON WEDNESDAY...THEN BACK INTO THE 20S THURSDAY AND FRIDAY.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
MN...NONE.
NE...NONE.
SD...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS LUBBOCK TX
1141 PM CST FRI DEC 7 2012
.UPDATE...
06Z AVIATION DISCUSSION BELOW. QUICK UPDATE THIS NIGHT TO ACCOUNT
FOR INCREASINGLY MOIST UPSLOPE CONDITIONS UNFOLDING ACROSS OUR
NERN COUNTIES BEHIND A SAGGING COLD FRONT. VISBYS ARE ALREADY AOB
5SM IN SWRN OKLAHOMA WHERE DEWPOINT DEPRESSIONS HAVE QUICKLY
NARROWED. RAP AND THE HRRR APPEAR CREDIBLE IN THIS COLD FRONT
DIPPING SWWD TO NEAR A TULIA TO GUTHRIE LINE BY 12Z...SO HAVE
UPDATED FOR MENTION OF AREAS OF FOG EAST OF THIS LINE ALONG WITH
STRATUS. CONTINUED RADIATIONAL COOLING IN ADVANCE OF HIGHER
DEWPOINTS BEHIND THE FRONT MAY FAVOR WIDESPREAD FOG AND PERHAPS
NECESSITATE A DENSE FOG ADVISORY IN THE COMING HOURS. WILL
MONITOR THIS SCENARIO CLOSELY.
&&
.AVIATION...
VFR AT LBB WITH MVFR CONDITIONS LIKELY DEVELOPING AT CDS AROUND
10Z. FRONTAL BOUNDARY HAS RECENTLY EDGED SOUTHWEST NEAR CDS AHEAD
OF MOIST E-NELY WINDS AND LIGHT FOG. SHORT-TERM MODELS SUGGEST
WIDESPREAD DENSE FOG AND LIFR STRATUS AT CDS AROUND 09Z...BUT AM
HEDGING MORE CONSERVATIVELY WITH MVFR VIS BEING PREDOMINANT WITH
TEMPO LIFR IN DENSE FOG. THIS FRONT SHOULD STALL SHORT OF LBB BY
12Z KEEPING VFR CONDITIONS INTACT...BUT WILL HAVE A HARD TIME
RETREATING. THIS SETUP FAVORS KEEPING CDS SUB-VFR THROUGH EARLY
AFTN UNDER STRATUS AND LIGHT SELY WINDS.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 29 65 26 39 14 / 0 0 0 10 30
TULIA 33 64 29 41 17 / 0 0 0 10 20
PLAINVIEW 33 65 29 42 19 / 0 0 0 10 20
LEVELLAND 30 68 32 45 19 / 0 0 0 10 30
LUBBOCK 31 68 33 45 20 / 0 0 0 10 20
DENVER CITY 35 69 35 48 21 / 0 0 0 10 20
BROWNFIELD 35 70 34 47 21 / 0 0 0 10 20
CHILDRESS 35 64 34 47 24 / 0 0 0 10 20
SPUR 36 68 38 48 22 / 0 0 0 0 20
ASPERMONT 37 72 38 52 26 / 0 0 0 0 10
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
93
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
533 AM EST SAT DEC 8 2012
.SYNOPSIS...
A SERIES OF LOW PRESSURE CENTERS MOVING NORTHEASTWARD ALONG A
STALLED FRONT WILL CONTINUE TO PROVIDE THE UPPER OHIO VALLEY WITH
MILD TEMPERATURES AND PERIODS OF RAIN INTO MONDAY. EXPECT A COOL
DOWN TO SEASONABLE TEMPERATURES TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
RECENT SURFACE AND RADAR DATA SHOW THE BATCH OF RAIN WILL HAVE EXITED
EAST PAST THE MOUNTAINS BY 7 AM. ANY LINGERING LOW VISIBILITY IN FOG
PATCHES NORTH WILL HAVE DISSIPATED BY THEN ALSO AS SURFACE WINDS
HAVE SLIGHTLY INCREASED TO 5 KTS.
RECENT RAP MODEL OUTPUT CONTINUES TO SHOW ANOTHER BATCH OF RAIN
SHOWERS CAN PASS EASTWARD ACROSS THE THE UPPER OHIO VALLEY DURING
TODAY. SO HAVE MENTIONED SCATTERED SHOWERS. HOWEVER ONCE THE LOW
PRESSURE CENTER FROM OHIO PASSES NORTHEASTWARD THROUGH LAKE ERIE
MIDDAY...RAIN SHOWERS WILL DECREASE IN COVERAGE WEST TO EAST THIS
AFTERNOON...LEAVING DRY CONDITIONS FOR MUCH OF TONIGHT.
PER BLEND OF RECENT GFS AND NAM MOS ALONG WITH GFS LAMP AND RAP
MODEL OUTPUT...FORECASTED TEMPERATURES TO CLIMB TO HIGHS THIS
AFTERNOON AT LEAST 15 DEGREES WARMER THAN NORMAL. POST SYSTEM
NORTHERLY WINDS TONIGHT WILL PROMOTE LOWS MORE THAN 10 DEGREES
COOLER THAN LAST NIGHT...BUT STILL ABOUT 10 DEGREES ABOVE NORMAL.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY/...
CONCUR WITH RECENT SREF MODEL OUTPUT WITH DETAILS FROM NAM AND
WRF-NMM MODELS THAT THERE WILL BE ANOTHER SURGE OF RAIN SPREADING
NORTHEASTWARD ACROSS THE UPPER OHIO VALLEY DAYTIME SUNDAY AND
SUNDAY NIGHT. THIS RAIN SURGE WILL BE ASSOCIATED WITH A LOW
PRESSURE CENTER MOVING NORTHEASTWARD FROM MISSOURI.
ONCE THE LOW PRESSURE CENTER PASSES NORTHEASTWARD THROUGH LAKE
ERIE MONDAY MORNING...THE RAIN WILL TAPER TO SHOWERS. COLDER
POSTFRONTAL AIR WILL CAN CAUSE TEMPERATURES TO FALL MONDAY
AFTERNOON. LINGERING SHOWERS MONDAY NIGHT CAN TURN TO LIGHT SNOW
SHOWERS BEFORE ENDING LATE. TUESDAY SHOULD CONTINUE TO BE MAINLY
CLOUDY DUE TO ENSUING COLD POOL.
FORECASTED TEMPERATURES TO BE CONSIDERABLY WARMER THAN NORMAL
SUNDAY INTO MONDAY MORNING...THEN COOL DOWN TO SEASONABLE VALUES
MONDAY NIGHT AND TUESDAY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
GFSE/ECMWF AGREE THAT HIGH PRESSURE WILL BUILD OVER THE AREA FROM
THE SOUTHWEST TUESDAY NIGHT AND WEDNESDAY. THAT FEATURE...ALONG
WITH A DEEP LAYER OF DRY AIR...WILL KEEP THE FORECAST DRY THROUGH
FRIDAY.
TEMPS THROUGH THE MID-WEEK WILL BE NEAR SEASONAL VALUES IN
THE COOLER AIR MASS BEHIND THE FRONT. READINGS ARE EXPECTED TO
MODERATE TO AROUND 5 DEGREES ABOVE NORMAL BY THE END OF THE WEEK
AS FLOW ALOFT BECOMES MORE SOUTHWESTERLY.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
WITH A BREAK IN PRECIPITATION AND WINDS PICKING UP FROM THE
SW...CEILINGS HAVE CLIMBED FROM LIFR/IFR AT MOST LOCATIONS TO MVFR.
CONSIDERING UPSTREAM OBSERVATIONS...APPEARS THAT EVEN IF RAIN
MOVES BACK INTO THE AREA DURING THE LATE MORNING AND EARLY
AFTERNOON HOURS...THERE IS A GOOD CHANCE THAT CONDITIONS WILL NOT
DROP BACK TO IFR LEVELS. EXPECT THAT SHOWERS WILL BE MORE
SCATTERED IN COVERAGE TODAY THAN YESTERDAY...WITH THE BEST CHANCE
TO THE SOUTH AND EAST OF PITTSBURGH.
THE REGION MAY GO COMPLETELY DRY TONIGHT...ALTHOUGH MVFR CIGS
WILL REMAIN. NEXT ROUND OF SHOWERS SHOULD HOLD OFF UNTIL
SUNDAY...ALTHOUGH THIS RAIN WILL BE INCLUDED IN THE 30 HOUR
PITTSBURGH TAF.
.OUTLOOK.../SUNDAY THROUGH WEDNESDAY/...
NEXT LOW PRESSURE SYSTEM WILL CAUSE RESTRICTIONS THROUGH TUESDAY
BEFORE COLD FRONT MOVES OUT OF THE REGION AND VFR CONDITIONS FINALLY
RETURN.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BILLINGS MT
324 AM MST SAT DEC 8 2012
.SHORT TERM...VALID FOR TDY AND SUN...
DYNAMIC SHORTWAVE CURRENTLY PUSHING WEST TO EAST THROUGH CENTRAL
MONTANA...WITH DIFFLUENT SIGNATURE OVER OUR SW MTNS...AND AS A
RESULT A HEALTHY SNOW BAND EXISTS NEAR LIVINGSTON...PINE CREEK
AND BIG TIMBER AS WELL AS OVER THE BEARTOOTH ABSAROKAS AS OF 10Z.
FORCING FROM THIS WAVE AND PACIFIC COLD FRONT WILL SLIDE EASTWARD
EARLY THIS MORNING GIVING A BRIEF PERIOD OF SNOW SHOWERS DESPITE
THE DOWNSLOPE WINDS. MORE WIDESPREAD PCPN WILL BE ASSOCIATED WITH
MOIST NW FLOW/TROWAL FROM LATER THIS MORNING INTO THIS EVENING.
THIS CLEARLY SEEN ON SATELLITE IMAGERY DROPPING THRU NORTH CENTRAL
MONTANA...WITH RAP ANALYSIS SHOWING N-NE MID LEVEL FLOW NEAR CUT
BANK AND HAVRE. PACIFIC COLD FRONT HAS PUSHED THROUGH LIVINGSTON
AND JUDITH GAP BUT CANADIAN FRONT IS STILL TO OUR NORTH BETWEEN
CUT BANK AND GREAT FALLS.
FORECAST IS ON TRACK WITH COMBINATION OF SNOW/NW WINDS/BLSN/WIND
CHILLS SET TO IMPACT OUR EASTERN AREAS THIS AFTERNOON AND
EVENING...AND IN FACT THIS IS WHERE STRONGEST WINDS AND DEEPEST
ASCENT WITH TROWAL WILL BE LOCATED. SO NO CHANGES TO ADVISORY IN
THESE AREAS. UPSLOPE FLOW AND GUSTY NW WINDS WILL ALSO FAVOR THE
BIG HORN MOUNTAINS AND WILL ADD THEM TO THE ADVISORY AS WELL...
THOUGH DENDRITIC LAYER STARTS TO BECOME TOO SHALLOW THIS EVENING
PER COLD MID LEVEL TEMPS TO NEAR -20C. OTHER AREA OF INTEREST IS
JUDITH GAP WHICH SHOULD RECEIVE 1-2 INCHES OF SNOW MAINLY THIS
MORNING INTO THE AFTERNOON...ALONG WITH STRONG NW WINDS ONCE COLD
ADVECTION KICKS IN...AND LIKELY SOME BLOWING SNOW AND POOR TRAVEL
CONDITIONS ON HIGHWAY 191.
SATELLITE IMAGERY SHOWS MOISTURE/COLD TOPS EXTENDING NORTHWARD
INTO THE CANADIAN ROCKIES...AND WILL NEED TO MONITOR ITS IMPACTS
AS THE SYSTEM EVOLVES SOUTHWARD. MODELS SHOWING BOUNDARY LAYER
CONVERGENCE SETTING UP LATE TODAY/THIS EVENING ONCE SFC RIDGE
BUILDS INTO OUR EASTERN PLAINS...SO WITH A CONTINUED FEED OF
MOISTURE FROM THE NORTH AND A TEMP PROFILE FAVORABLE FOR DENDRITIC
SNOW GROWTH FEEL THAT OUR WESTERN FOOTHILLS AND PARK COUNTY MAY
RECEIVE A LONGER DURATION AND GREATER SNOWFALL THAN PREVIOUSLY
THOUGHT. FOR NOW HAVE RAISED POPS AND GIVEN LIVINGSTON/PINE
CREEK/RED LODGE AREAS UP TO ABOUT 2 INCHES OF SNOW. WIND WILL BE
MUCH LESS OF AN ISSUE IN THESE AREAS HOWEVER.
AS FOR BILLINGS...SOME MORNING SNOW SHOWERS ALONG PACIFIC FRONT
WILL GIVE WAY TO A PERIOD OF SNOW FROM LATE MORNING THROUGH MOST
OF THE AFTERNOON ONCE WINDS SHIFT NORTH AND WE SEE IMPACTS FROM
TROWAL. SOME DOWNSLOPING OFF THE BULL MTNS COULD BE A FACTOR...BUT
THINK SOMEWHERE NEAR AN INCH OF SNOW IS IN STORE FOR THE CITY...
PERHAPS A BIT MORE IF A CONVERGENT BAND DEVELOPS...ALONG WITH A
GUSTY NORTH WIND. WILL FEEL LIKE WINTER TODAY.
SYSTEM WILL WIND DOWN TONIGHT...WITH A COLD NIGHT IN STORE AS
CANADIAN SURFACE RIDGE BUILDS IN. CURRENT TEMPS IN SOUTHERN
ALBERTA ARE IN THE SINGLE DIGITS/MID TEENS SO WILL PROBABLY SEE
TEMPS PUSH THESE LEVELS BY LATE AFTERNOON PER POST FRONTAL
ADVECTION. IF SKIES CLEAR OUT TONIGHT...WITH LIGHT WINDS AND A
LITTLE FRESH SNOW COVER...LOWS IN THE SINGLE DIGITS OR NEAR ZERO
ARE A GOOD BET. BILLINGS SHOULD SEE ITS COLDEST TEMP YET OF THE
SEASON...SO FAR THE 6 ABOVE ON NOVEMBER 11TH STILL STANDS...AND
BELOW ZERO IS NOT OUT OF THE QUESTION.
SUNDAY WILL BE DRY/CHILLY UNDER THE INFLUENCE OF SFC RIDGE AND
POOR MIXING. KLONDIKE CHINOOK WILL COMMENCE OUT WEST BY
AFTERNOON...AND DOWNSLOPE GRADIENTS REALLY TIGHTEN UP SUNDAY
NIGHT. THIS WILL LEAD TO WIND CONCERNS ALONG THE FOOTHILLS AND
ALSO NEAR BIG TIMBER AND HARLOWTON...WHICH WILL ALSO BE FAVORED
UNDER NW FLOW ALOFT.
JKL
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
THE EXTENDED FORECAST CONTINUES TO REMAIN IN GOOD SHAPE...SO MADE
ONLY MINOR CHANGES...MOSTLY TO INCREASE POPS LATE WEDNESDAY INTO
EARLY THURSDAY AND TO TWEAK WINDS THROUGH THE EXTENDED. THE MAIN
THEME FOR MONDAY THROUGH WEDNESDAY OF NEXT WEEK CONTINUES TO BE
WINDY AND UNSETTLED WEATHER. ON MONDAY...MOIST NORTHWESTERLY FLOW
AND AN EMBEDDED SHORTWAVE WILL BRING SNOW SHOWERS TO MUCH OF THE
FORECAST AREA. PRESSURE FALLS AHEAD OF A SURFACE LOW WILL BRING
GUSTY WESTERLY WINDS ON MONDAY AS WELL. THESE DOWNSLOPE WINDS WILL
KEEP HIGH TEMPS IN THE 30S MONDAY...AND MAY WORK AGAINST SOME OF
THE LIFT ASSOCIATED WITH THE SHORTWAVE AND UPPER LEVEL DYNAMICS.
TUESDAY WILL BRING A BRIEF BREAK IN THE UNSETTLED WEATHER WITH
RIDGING ALOFT. HOWEVER...WINDS WILL INCREASE ON TUESDAY AFTERNOON
ACROSS THE WEST IN RESPONSE A TIGHTENING PRESSURE GRADIENT AND
PRESSURE FALLS NORTH OF THE FORECAST AREA.
BOTH THE ECMWF AND THE GFS ARE CONTINUING TO COME INTO AGREEMENT
REGARDING A PUSH OF COLD AIR INTO THE FORECAST AREA FROM THE
NORTH ON WEDNESDAY AFTERNOON AND OVERNIGHT. MODELS ARE CONSISTENT
WITH DEVELOPING SOME SNOWFALL ALONG THE FRONTOGENESIS ZONE
WEDNESDAY NIGHT AND THURSDAY. TWEAKED TEMPERATURES UPWARDS JUST A
BIT THURSDAY AS MODELS CONTINUE TO TREND TEMPS UP EVER SO
SLIGHTLY.
WEAK RIDGING BUILDS INTO THE REGION FRIDAY...KEEPING MUCH OF THE
REGION DRY...WITH HIGH TEMPS REBOUNDING INTO THE UPPER 20S TO MID
30S. THERE ARE SOME NOTABLE DIFFERENCES IN HOW THE MODELS HANDLE
THE FRIDAY NIGHT TO SATURDAY NIGHT TIMEFRAME...THUS CONFIDENCE IN
THE FORECAST DURING THIS PERIOD IS SOMEWHAT LOW. WOULD LIKE TO SEE
SOME BETTER AGREEMENT BEFORE MAKING SUBSTANTIAL CHANGES TO THE END
OF THE EXTENDED. FOR NOW...KEPT THE FRIDAY NIGHT TO SATURDAY NIGHT
TIMEFRAME MAINLY DRY WITH SEASONAL TEMPERATURES. STC
&&
.AVIATION...
A STORM SYSTEM WILL MOVE THROUGH THE REGION TODAY...ACCOMPANIED BY
A STRONG COLD FRONT. EXPECT CONDITIONS TO DETERIORATE THROUGH THE
MORNING ACROSS MUCH OF THE REGION WITH MVFR/IFR AND LOCALIZED
LIFR/VLIFR CONDITIONS IN SNOW AND LOW CEILINGS LIKELY INTO THIS
EVENING. WINDS WILL SWITCH TO A NW DIRECTION BY MID DAY AT ALL TAF
SITES AND BECOME VERY GUSTY. THE STRONG WINDS WILL INCREASE THE
LIKELIHOOD OF REDUCED VISIBILITY DUE TO BLOWING SNOW. CONDITIONS
WILL IMPROVE TONIGHT AS THE STORM SYSTEM MOVES EAST OF THE REGION
AND WINDS BEGIN TO SUBSIDE. STC
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 028 005/024 020/034 021/037 025/034 015/023 010/032
7/S 30/B 25/S 21/N 14/S 32/S 11/B
LVM 024 000/022 018/031 018/033 025/033 014/026 011/030
6/S 20/N 35/S 31/N 34/S 43/S 11/N
HDN 027 002/025 011/034 018/035 020/039 012/024 008/031
9/S 40/B 35/S 21/B 13/S 32/S 11/B
MLS 025 901/018 011/033 019/034 023/029 010/019 006/027
9/S 60/B 14/S 21/B 13/S 21/E 11/B
4BQ 028 001/020 010/031 017/033 018/034 013/024 006/031
9/S 91/E 15/S 21/B 12/S 32/S 11/B
BHK 025 902/013 008/032 018/032 019/028 010/018 006/027
9/S 80/E 13/S 21/B 12/S 21/E 11/B
SHR 030 003/021 011/032 015/033 017/036 011/024 005/028
8/S 60/B 24/S 31/B 12/S 33/S 11/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY IN EFFECT FROM NOON TODAY TO 6 AM MST
SUNDAY FOR ZONES 31>33-36>38-58.
WINTER WEATHER ADVISORY IN EFFECT UNTIL MIDNIGHT MST TONIGHT
FOR ZONE 63.
WY...WINTER WEATHER ADVISORY IN EFFECT FROM NOON TODAY TO 6 AM MST
SUNDAY FOR ZONE 99.
WINTER WEATHER ADVISORY IN EFFECT UNTIL 6 AM MST SUNDAY FOR
ZONE 98.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
624 AM CST SAT DEC 8 2012
.UPDATE...
.DISCUSSION...
A NEW FORECAST IS IN PLACE...MAINLY AFFECTING NORTHERN NEBRASKA.
THE RAP MODEL...WHICH HAS BEEN PERFORMING WELL WITH THIS
SYSTEM...SUGGESTS THE SFC LOW WILL TRACK ALONG THE SD-NEB BORDER
LATE THIS AFTN AND THIS EVENING. THIS IS ABOUT 100 MILES OR SO
FARTHER SOUTH THAN THE ENSEMBLE FCST.
IT ALSO CARRIES THE PV15 CENTER FARTHER SOUTH. ENHANCED
ADVECTIONS OF TEMPERATURE AND MOISTURE SHOW A MARKED STRENGTHENING
OF 700 MB FRONTOGENESIS NEAR THE SFC LOW LATE THIS AFTN AND THIS
EVENING. THUS...AS INDICATED BY THE MODEL...GREATER POPS AND QPF
ARE WARRANTED FOR NRN NEB WITH A RAIN CHANGEOVER TO SNOW WITH THE
PASSAGE OF A PACIFIC FRONT EARLY THIS EVENING FOLLOWED BY ARCTIC
AIR MOVING IN AROUND 06Z OR LATER.
POPS ARE HELD AT 40 PERCENT GIVEN THE UNCERTAINTIES OF THIS
RAPID CHANGE IN THE MODEL AND THE MIXED PCPN WOULD PERHAPS YEILD
AN INCH OR TWO OF SNOW. THE REST OF THE FCST IS ON TRACK.
&&
.PREV DISCUSSION... /ISSUED 533 AM CST SAT DEC 8 2012/
UPDATE...
AVIATION...
MVFR CIGS ARE EXPECTED IN SOME AREAS TODAY AND TONIGHT.
THE RUC MODEL...WHICH HAS BEEN PERFORMING WELL...SHOWS THE
MVFR/LOCAL IFR CIGS ACROSS NCNTL NEB LIFTING NORTH THIS AFTERNOON
WITH MVFR CIGS FILLING IN AGAIN TONIGHT AS AN ARCTIC FRONT MOVES
INTO WRN/NCNTL NEB.
MEANWHILE A WARM FRONT DEVELOPING ACROSS SRN NEB THIS MORNING WILL
LIFT NORTH DURING THE DAY TODAY PRODUCING ISOLATED RAIN AND SNOW
SHOWERS AND LOCAL MVFR CIGS. ADDITIONAL SCATTERED SNOW SHOWERS/MVFR
CIGS ARE EXPECTED TONIGHT ALONG AND BEHIND THE ARCTIC FRONT.
WINDS ALONG AND BEHIND THE FRONT WILL INCREASE TO 32025G35KT TONIGHT.
PREV DISCUSSION... /ISSUED 400 AM CST SAT DEC 8 2012/
SYNOPSIS...
EVENING HAND ANALYSIS OF THE H5 LEVEL REVEALS A BROAD LONGWAVE
TROUGH ENCOMPASSING MUCH OF THE CONTIGUOUS 48...WITH RIDGING OFF
BOTH THE WESTERN AND EASTERN COASTS. SEVERAL SHORTWAVES ARE SEEN
MOVING THROUGH THE BROAD TROUGH...WITH ONE NOW EAST OF THE UPPER
MISSISSIPPI VALLEY...AND THE NEXT APPROACHING THE NORTHERN/CENTRAL
HIGH PLAINS FROM THE WEST. AT THE SURFACE...AN AREA OF LOW PRESSURE
IS STARTING TO DEEPEN OVER CENTRAL MONTANA WITH HIGH PRESSURE
LOCATED OVER THE MISSOURI VALLEY. WHILE WINDS ARE FAIRLY LIGHT AND
VARIABLE AT THIS HOUR ACROSS THE CWA...FURTHER WEST ACROSS THE HIGH
PLAINS...SURFACE WINDS ARE STARTING TO TAKE ON A MORE SOUTHERLY
COMPONENT. TEMPERATURES EARLY THIS AM RANGE FROM A CHILLY 13
DEGREES FAHRENHEIT AT KLBF...TO AS WARM AS 30 AT KONL WHERE STRATUS
IS LOCKED IN PLACE.
DISCUSSION...
SHORT TERM...TONIGHT THROUGH 12Z TUESDAY. MAIN FORECAST CONCERNS
OVER THE NEXT 72 HOURS INVOLVES THE THREAT OF LIGHT SNOW...A RETURN
OF COLD TEMPERATURES...AND THE POTENTIAL OF ADVISORY CRITERIA WIND
SPEEDS.
MODELS CONTINUE TO SHOW GOOD AGREEMENT IN THE NEAR TERM IN WHICH THE
WESTERN SHORTWAVE TROUGH AND ASSOCIATED SURFACE LOW DEEPEN AND EJECT
EAST ACROSS THE NORTHERN PLAINS...DRAGGING A STRONG COLD FRONT
THROUGH THE CWA LATE TODAY/OVERNIGHT TONIGHT. THE STRONGEST OMEGA
CONTINUES TO BE SUGGESTED WELL NORTH OF THE CWA...IN CLOSE VICINITY
TO THE TROUGH AXIS...HOWEVER MOST NEAR TERM MODEL SOLUTIONS GENERATE
LIGHT QPF AHEAD OF A MID-LEVEL FGEN BAND WHERE WEAK THERMAL
ADVECTION AND A BRIEF PERIOD OF UPGLIDE MAY BE SUFFICIENT ENOUGH TO
SQUEEZE OUT A HUNDREDTH OR TWO OF AN INCH OF PRECIPITATION THIS
AFTERNOON. THE BETTER DYNAMICS FOR PRECIPITATION PRODUCTION ARRIVES
WITH THE MID LEVEL FRONTOGENETIC BAND LATE THIS
AFTERNOON/EVENING...HOWEVER FORECAST PROXIMITY SOUNDINGS FROM ACROSS
THE CWA SUGGEST THE LOWER LEVELS OF THE ATMOSPHERE WILL QUICKLY DRY
OUT AS STRONG COLD/DRY AIR ADVECTION SPILLS IN BEHIND THE PASSING
BOUNDARY. THE ENSEMBLES...AND DETERMINISTIC SOLUTIONS ALL HAVE
CONVERGED THAT AT MOST LESS THAN .05 OF AN INCH OF QPF WOULD BE
GENERATED...SO ONLY LOOKING FOR A DUSTING TO POSSIBLY A HALF OF AN
INCH ACROSS THE SANDHILLS AND POINTS SOUTHEAST WHERE ADDITIONAL LIFT
MAY BE GENERATED WITHIN THE VICINITY OF THE RIGHT ENTRANCE OF A
PASSING UPPER JET. ACROSS NORTHERN NEBRASKA...THE NEAR TERM
CONSENSUS IS SUGGESTING A PERIOD OF POSSIBLE WRAP AROUND AS THE
SURFACE LOW ADVANCES INTO WEST CENTRAL MINNESOTA...THE POTENTIAL OF
SLIGHTLY HEAVIER SNOW ACCUMULATION EXIST...BUT LESS THAN AN INCH
WOULD BE EXPECT AT BEST WITH THE SNOW FALLING OVERNIGHT TONIGHT.
THE SHORTWAVE QUICKLY ADVANCES EAST OVERNIGHT BRINGING AN END TO
PRECIPITATION CHANCES FOR THE FORESEEABLE FUTURE AS AN OVERALL LACK
OF KINEMATIC FORCING IS SUGGESTED IN THE SHORT AND LONG TERM
SOLUTIONS.
STRONG COLD AIR ADVECTION AND MODEST LOW LEVEL PRESSURE RISES WILL
FOLLOW THE SURFACE BOUNDARY PASSAGE OVERNIGHT TONIGHT. THE
PRESSURE RISES WILL HELP TIGHTEN THE SURFACE GRADIENT AND ALLOW FOR
GUSTY CONDITIONS EARLY ON SUNDAY. THE MODELS HAVE SHOWN A SLIGHT
NORTHWARD TREND IN THE TRACK OF THE SURFACE LOW...NOW ACROSS WEST
CENTRAL MINNESOTA. THIS TRACK FAVORS SLIGHTLY WEAKER SURFACE WINDS
THAN PREVIOUSLY ANTICIPATED. SO WILL KEEP WIND SPEEDS BELOW
ADVISORY CRITERIA...ESPECIALLY SINCE THE STRONGEST PRESSURE RISES
ARE EXPECTED DURING THE EARLY MORNING HOURS...DIURNALLY UNFAVORABLE
FOR ADVISORY CRITERIA WIND. BUT...WIDESPREAD SUB ZERO WIND CHILLS
WILL BE POSSIBLE...WITH THE POTENTIAL OF SOME OF THE LOWEST READINGS
APPROACHING MINUS TEN OR COLDER AS H9 TEMPERATURES FALL AS COLD AS
MINUS 12C ACROSS OUR NORTHERN ZONES. HIGHS ON SUNDAY WILL BE
CHILLY...WITH READINGS RANGING FROM THE UPPER TEENS ACROSS THE
NORTH...TO THE UPPER 20S ACROSS THE FAR SOUTHWEST. WE WILL NEED TO
WATCH LOW TEMPERATURES FOR MONDAY MORNING...AS ANY SNOWFALL WOULD
ALLOW READINGS TO PLUMMET...TO POSSIBLY BELOW 0F. WILL KEEP
FORECAST VALUES IN THE SINGLE DIGITS FOR NOW...AS WIDESPREAD
ACCUMULATING SNOW IS NOT ANTICIPATED. TEMPERATURES BEGIN TO MODERATE
SLOWLY MONDAY AFTERNOON AS WEAK WAA INFILTRATES FROM THE WEST IN
ADVANCE OF THE NEXT SHORTWAVE TROUGH.
LONG TERM...12Z TUESDAY AND BEYOND. THE NEXT WAVE PASSES THROUGH
EARLY TUESDAY...HOWEVER MOISTURE REMAINS IN QUESTION...AND KINEMATIC
FORCING REMAINS SOMEWHAT WEAK AND TO THE SOUTH...THUS CONFIDENCE IS
TOO LOW TO INTRODUCE POPS INTO THE FORECAST. OTHERWISE SHORTWAVE
RIDGING AND WAA TAKE HOLD THROUGH THE END OF NEXT WEEK...WITH
TEMPERATURES REMAINING NEAR TO SLIGHTLY ABOVE SEASONAL NORMS. THE
NEXT SIGNIFICANT TROUGH IS SHOWN TO ARRIVE ACROSS THE WEST LATE NEXT
WEEK...BUT WITH THIS EVENINGS MODEL RUNS...PRECIPITATION CHANCES
LOOK TO REMAIN WELL TO THE SOUTH AND WEST OF THE CWA.
AVIATION...
MVFR/LOCAL IFR CIGS ARE EXPECTED IN SOME AREAS TODAY AND TONIGHT.
THE RUC MODEL...WHICH HAS BEEN PERFORMING WELL...SHOWS THE MVFR/IFR
CIGS ACROSS NCNTL NEB LIFTING NORTH THIS AFTERNOON WITH MVFR CIGS
FILLING IN AGAIN AS AN ARCTIC FRONT MOVES INTO WRN/NCNTL NEB TONIGHT.
MEANWHILE A WARM FRONT DEVELOPING ACROSS SRN NEB THIS MORNING WILL
LIFT NORTH DURING THE DAY TODAY PRODUCING ISOLATED RAIN AND SNOW
SHOWERS AND LOCAL MVFR CIGS. ADDITIONAL SCATTERED SNOW SHOWERS/MVFR
CIGS ARE EXPECTED TONIGHT ALONG AND BEHIND THE ARCTIC FRONT.
WINDS ALONG AND BEHIND THE FRONT WILL INCREASE TO 32025G35KT TONIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
533 AM CST SAT DEC 8 2012
.UPDATE...
.AVIATION...
MVFR CIGS ARE EXPECTED IN SOME AREAS TODAY AND TONIGHT.
THE RUC MODEL...WHICH HAS BEEN PERFORMING WELL...SHOWS THE
MVFR/LOCAL IFR CIGS ACROSS NCNTL NEB LIFTING NORTH THIS AFTERNOON
WITH MVFR CIGS FILLING IN AGAIN TONIGHT AS AN ARCTIC FRONT MOVES
INTO WRN/NCNTL NEB.
MEANWHILE A WARM FRONT DEVELOPING ACROSS SRN NEB THIS MORNING WILL
LIFT NORTH DURING THE DAY TODAY PRODUCING ISOLATED RAIN AND SNOW
SHOWERS AND LOCAL MVFR CIGS. ADDITIONAL SCATTERED SNOW SHOWERS/MVFR
CIGS ARE EXPECTED TONIGHT ALONG AND BEHIND THE ARCTIC FRONT.
WINDS ALONG AND BEHIND THE FRONT WILL INCREASE TO 32025G35KT TONIGHT.
&&
.PREV DISCUSSION... /ISSUED 400 AM CST SAT DEC 8 2012/
SYNOPSIS...
EVENING HAND ANALYSIS OF THE H5 LEVEL REVEALS A BROAD LONGWAVE
TROUGH ENCOMPASSING MUCH OF THE CONTIGUOUS 48...WITH RIDGING OFF
BOTH THE WESTERN AND EASTERN COASTS. SEVERAL SHORTWAVES ARE SEEN
MOVING THROUGH THE BROAD TROUGH...WITH ONE NOW EAST OF THE UPPER
MISSISSIPPI VALLEY...AND THE NEXT APPROACHING THE NORTHERN/CENTRAL
HIGH PLAINS FROM THE WEST. AT THE SURFACE...AN AREA OF LOW PRESSURE
IS STARTING TO DEEPEN OVER CENTRAL MONTANA WITH HIGH PRESSURE
LOCATED OVER THE MISSOURI VALLEY. WHILE WINDS ARE FAIRLY LIGHT AND
VARIABLE AT THIS HOUR ACROSS THE CWA...FURTHER WEST ACROSS THE HIGH
PLAINS...SURFACE WINDS ARE STARTING TO TAKE ON A MORE SOUTHERLY
COMPONENT. TEMPERATURES EARLY THIS AM RANGE FROM A CHILLY 13
DEGREES FAHRENHEIT AT KLBF...TO AS WARM AS 30 AT KONL WHERE STRATUS
IS LOCKED IN PLACE.
DISCUSSION...
SHORT TERM...TONIGHT THROUGH 12Z TUESDAY. MAIN FORECAST CONCERNS
OVER THE NEXT 72 HOURS INVOLVES THE THREAT OF LIGHT SNOW...A RETURN
OF COLD TEMPERATURES...AND THE POTENTIAL OF ADVISORY CRITERIA WIND
SPEEDS.
MODELS CONTINUE TO SHOW GOOD AGREEMENT IN THE NEAR TERM IN WHICH THE
WESTERN SHORTWAVE TROUGH AND ASSOCIATED SURFACE LOW DEEPEN AND EJECT
EAST ACROSS THE NORTHERN PLAINS...DRAGGING A STRONG COLD FRONT
THROUGH THE CWA LATE TODAY/OVERNIGHT TONIGHT. THE STRONGEST OMEGA
CONTINUES TO BE SUGGESTED WELL NORTH OF THE CWA...IN CLOSE VICINITY
TO THE TROUGH AXIS...HOWEVER MOST NEAR TERM MODEL SOLUTIONS GENERATE
LIGHT QPF AHEAD OF A MID-LEVEL FGEN BAND WHERE WEAK THERMAL
ADVECTION AND A BRIEF PERIOD OF UPGLIDE MAY BE SUFFICIENT ENOUGH TO
SQUEEZE OUT A HUNDREDTH OR TWO OF AN INCH OF PRECIPITATION THIS
AFTERNOON. THE BETTER DYNAMICS FOR PRECIPITATION PRODUCTION ARRIVES
WITH THE MID LEVEL FRONTOGENETIC BAND LATE THIS
AFTERNOON/EVENING...HOWEVER FORECAST PROXIMITY SOUNDINGS FROM ACROSS
THE CWA SUGGEST THE LOWER LEVELS OF THE ATMOSPHERE WILL QUICKLY DRY
OUT AS STRONG COLD/DRY AIR ADVECTION SPILLS IN BEHIND THE PASSING
BOUNDARY. THE ENSEMBLES...AND DETERMINISTIC SOLUTIONS ALL HAVE
CONVERGED THAT AT MOST LESS THAN .05 OF AN INCH OF QPF WOULD BE
GENERATED...SO ONLY LOOKING FOR A DUSTING TO POSSIBLY A HALF OF AN
INCH ACROSS THE SANDHILLS AND POINTS SOUTHEAST WHERE ADDITIONAL LIFT
MAY BE GENERATED WITHIN THE VICINITY OF THE RIGHT ENTRANCE OF A
PASSING UPPER JET. ACROSS NORTHERN NEBRASKA...THE NEAR TERM
CONSENSUS IS SUGGESTING A PERIOD OF POSSIBLE WRAP AROUND AS THE
SURFACE LOW ADVANCES INTO WEST CENTRAL MINNESOTA...THE POTENTIAL OF
SLIGHTLY HEAVIER SNOW ACCUMULATION EXIST...BUT LESS THAN AN INCH
WOULD BE EXPECT AT BEST WITH THE SNOW FALLING OVERNIGHT TONIGHT.
THE SHORTWAVE QUICKLY ADVANCES EAST OVERNIGHT BRINGING AN END TO
PRECIPITATION CHANCES FOR THE FORESEEABLE FUTURE AS AN OVERALL LACK
OF KINEMATIC FORCING IS SUGGESTED IN THE SHORT AND LONG TERM
SOLUTIONS.
STRONG COLD AIR ADVECTION AND MODEST LOW LEVEL PRESSURE RISES WILL
FOLLOW THE SURFACE BOUNDARY PASSAGE OVERNIGHT TONIGHT. THE
PRESSURE RISES WILL HELP TIGHTEN THE SURFACE GRADIENT AND ALLOW FOR
GUSTY CONDITIONS EARLY ON SUNDAY. THE MODELS HAVE SHOWN A SLIGHT
NORTHWARD TREND IN THE TRACK OF THE SURFACE LOW...NOW ACROSS WEST
CENTRAL MINNESOTA. THIS TRACK FAVORS SLIGHTLY WEAKER SURFACE WINDS
THAN PREVIOUSLY ANTICIPATED. SO WILL KEEP WIND SPEEDS BELOW
ADVISORY CRITERIA...ESPECIALLY SINCE THE STRONGEST PRESSURE RISES
ARE EXPECTED DURING THE EARLY MORNING HOURS...DIURNALLY UNFAVORABLE
FOR ADVISORY CRITERIA WIND. BUT...WIDESPREAD SUB ZERO WIND CHILLS
WILL BE POSSIBLE...WITH THE POTENTIAL OF SOME OF THE LOWEST READINGS
APPROACHING MINUS TEN OR COLDER AS H9 TEMPERATURES FALL AS COLD AS
MINUS 12C ACROSS OUR NORTHERN ZONES. HIGHS ON SUNDAY WILL BE
CHILLY...WITH READINGS RANGING FROM THE UPPER TEENS ACROSS THE
NORTH...TO THE UPPER 20S ACROSS THE FAR SOUTHWEST. WE WILL NEED TO
WATCH LOW TEMPERATURES FOR MONDAY MORNING...AS ANY SNOWFALL WOULD
ALLOW READINGS TO PLUMMET...TO POSSIBLY BELOW 0F. WILL KEEP
FORECAST VALUES IN THE SINGLE DIGITS FOR NOW...AS WIDESPREAD
ACCUMULATING SNOW IS NOT ANTICIPATED. TEMPERATURES BEGIN TO MODERATE
SLOWLY MONDAY AFTERNOON AS WEAK WAA INFILTRATES FROM THE WEST IN
ADVANCE OF THE NEXT SHORTWAVE TROUGH.
LONG TERM...12Z TUESDAY AND BEYOND. THE NEXT WAVE PASSES THROUGH
EARLY TUESDAY...HOWEVER MOISTURE REMAINS IN QUESTION...AND KINEMATIC
FORCING REMAINS SOMEWHAT WEAK AND TO THE SOUTH...THUS CONFIDENCE IS
TOO LOW TO INTRODUCE POPS INTO THE FORECAST. OTHERWISE SHORTWAVE
RIDGING AND WAA TAKE HOLD THROUGH THE END OF NEXT WEEK...WITH
TEMPERATURES REMAINING NEAR TO SLIGHTLY ABOVE SEASONAL NORMS. THE
NEXT SIGNIFICANT TROUGH IS SHOWN TO ARRIVE ACROSS THE WEST LATE NEXT
WEEK...BUT WITH THIS EVENINGS MODEL RUNS...PRECIPITATION CHANCES
LOOK TO REMAIN WELL TO THE SOUTH AND WEST OF THE CWA.
AVIATION...
MVFR/LOCAL IFR CIGS ARE EXPECTED IN SOME AREAS TODAY AND TONIGHT.
THE RUC MODEL...WHICH HAS BEEN PERFORMING WELL...SHOWS THE MVFR/IFR
CIGS ACROSS NCNTL NEB LIFTING NORTH THIS AFTERNOON WITH MVFR CIGS
FILLING IN AGAIN AS AN ARCTIC FRONT MOVES INTO WRN/NCNTL NEB TONIGHT.
MEANWHILE A WARM FRONT DEVELOPING ACROSS SRN NEB THIS MORNING WILL
LIFT NORTH DURING THE DAY TODAY PRODUCING ISOLATED RAIN AND SNOW
SHOWERS AND LOCAL MVFR CIGS. ADDITIONAL SCATTERED SNOW SHOWERS/MVFR
CIGS ARE EXPECTED TONIGHT ALONG AND BEHIND THE ARCTIC FRONT.
WINDS ALONG AND BEHIND THE FRONT WILL INCREASE TO 32025G35KT TONIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
400 AM CST SAT DEC 8 2012
.SYNOPSIS...
EVENING HAND ANALYSIS OF THE H5 LEVEL REVEALS A BROAD LONGWAVE
TROUGH ENCOMPASSING MUCH OF THE CONTIGUOUS 48...WITH RIDGING OFF
BOTH THE WESTERN AND EASTERN COASTS. SEVERAL SHORTWAVES ARE SEEN
MOVING THROUGH THE BROAD TROUGH...WITH ONE NOW EAST OF THE UPPER
MISSISSIPPI VALLEY...AND THE NEXT APPROACHING THE NORTHERN/CENTRAL
HIGH PLAINS FROM THE WEST. AT THE SURFACE...AN AREA OF LOW PRESSURE
IS STARTING TO DEEPEN OVER CENTRAL MONTANA WITH HIGH PRESSURE
LOCATED OVER THE MISSOURI VALLEY. WHILE WINDS ARE FAIRLY LIGHT AND
VARIABLE AT THIS HOUR ACROSS THE CWA...FURTHER WEST ACROSS THE HIGH
PLAINS...SURFACE WINDS ARE STARTING TO TAKE ON A MORE SOUTHERLY
COMPONENT. TEMPERATURES EARLY THIS AM RANGE FROM A CHILLY 13
DEGREES FAHRENHEIT AT KLBF...TO AS WARM AS 30 AT KONL WHERE STRATUS
IS LOCKED IN PLACE.
&&
.DISCUSSION...
SHORT TERM...TONIGHT THROUGH 12Z TUESDAY. MAIN FORECAST CONCERNS
OVER THE NEXT 72 HOURS INVOLVES THE THREAT OF LIGHT SNOW...A RETURN
OF COLD TEMPERATURES...AND THE POTENTIAL OF ADVISORY CRITERIA WIND
SPEEDS.
MODELS CONTINUE TO SHOW GOOD AGREEMENT IN THE NEAR TERM IN WHICH THE
WESTERN SHORTWAVE TROUGH AND ASSOCIATED SURFACE LOW DEEPEN AND EJECT
EAST ACROSS THE NORTHERN PLAINS...DRAGGING A STRONG COLD FRONT
THROUGH THE CWA LATE TODAY/OVERNIGHT TONIGHT. THE STRONGEST OMEGA
CONTINUES TO BE SUGGESTED WELL NORTH OF THE CWA...IN CLOSE VICINITY
TO THE TROUGH AXIS...HOWEVER MOST NEAR TERM MODEL SOLUTIONS GENERATE
LIGHT QPF AHEAD OF A MID-LEVEL FGEN BAND WHERE WEAK THERMAL
ADVECTION AND A BRIEF PERIOD OF UPGLIDE MAY BE SUFFICIENT ENOUGH TO
SQUEEZE OUT A HUNDREDTH OR TWO OF AN INCH OF PRECIPITATION THIS
AFTERNOON. THE BETTER DYNAMICS FOR PRECIPITATION PRODUCTION ARRIVES
WITH THE MID LEVEL FRONTOGENETIC BAND LATE THIS
AFTERNOON/EVENING...HOWEVER FORECAST PROXIMITY SOUNDINGS FROM ACROSS
THE CWA SUGGEST THE LOWER LEVELS OF THE ATMOSPHERE WILL QUICKLY DRY
OUT AS STRONG COLD/DRY AIR ADVECTION SPILLS IN BEHIND THE PASSING
BOUNDARY. THE ENSEMBLES...AND DETERMINISTIC SOLUTIONS ALL HAVE
CONVERGED THAT AT MOST LESS THAN .05 OF AN INCH OF QPF WOULD BE
GENERATED...SO ONLY LOOKING FOR A DUSTING TO POSSIBLY A HALF OF AN
INCH ACROSS THE SANDHILLS AND POINTS SOUTHEAST WHERE ADDITIONAL LIFT
MAY BE GENERATED WITHIN THE VICINITY OF THE RIGHT ENTRANCE OF A
PASSING UPPER JET. ACROSS NORTHERN NEBRASKA...THE NEAR TERM
CONSENSUS IS SUGGESTING A PERIOD OF POSSIBLE WRAP AROUND AS THE
SURFACE LOW ADVANCES INTO WEST CENTRAL MINNESOTA...THE POTENTIAL OF
SLIGHTLY HEAVIER SNOW ACCUMULATION EXIST...BUT LESS THAN AN INCH
WOULD BE EXPECT AT BEST WITH THE SNOW FALLING OVERNIGHT TONIGHT.
THE SHORTWAVE QUICKLY ADVANCES EAST OVERNIGHT BRINGING AN END TO
PRECIPITATION CHANCES FOR THE FORESEEABLE FUTURE AS AN OVERALL LACK
OF KINEMATIC FORCING IS SUGGESTED IN THE SHORT AND LONG TERM
SOLUTIONS.
STRONG COLD AIR ADVECTION AND MODEST LOW LEVEL PRESSURE RISES WILL
FOLLOW THE SURFACE BOUNDARY PASSAGE OVERNIGHT TONIGHT. THE
PRESSURE RISES WILL HELP TIGHTEN THE SURFACE GRADIENT AND ALLOW FOR
GUSTY CONDITIONS EARLY ON SUNDAY. THE MODELS HAVE SHOWN A SLIGHT
NORTHWARD TREND IN THE TRACK OF THE SURFACE LOW...NOW ACROSS WEST
CENTRAL MINNESOTA. THIS TRACK FAVORS SLIGHTLY WEAKER SURFACE WINDS
THAN PREVIOUSLY ANTICIPATED. SO WILL KEEP WIND SPEEDS BELOW
ADVISORY CRITERIA...ESPECIALLY SINCE THE STRONGEST PRESSURE RISES
ARE EXPECTED DURING THE EARLY MORNING HOURS...DIURNALLY UNFAVORABLE
FOR ADVISORY CRITERIA WIND. BUT...WIDESPREAD SUB ZERO WIND CHILLS
WILL BE POSSIBLE...WITH THE POTENTIAL OF SOME OF THE LOWEST READINGS
APPROACHING MINUS TEN OR COLDER AS H9 TEMPERATURES FALL AS COLD AS
MINUS 12C ACROSS OUR NORTHERN ZONES. HIGHS ON SUNDAY WILL BE
CHILLY...WITH READINGS RANGING FROM THE UPPER TEENS ACROSS THE
NORTH...TO THE UPPER 20S ACROSS THE FAR SOUTHWEST. WE WILL NEED TO
WATCH LOW TEMPERATURES FOR MONDAY MORNING...AS ANY SNOWFALL WOULD
ALLOW READINGS TO PLUMMET...TO POSSIBLY BELOW 0F. WILL KEEP
FORECAST VALUES IN THE SINGLE DIGITS FOR NOW...AS WIDESPREAD
ACCUMULATING SNOW IS NOT ANTICIPATED. TEMPERATURES BEGIN TO MODERATE
SLOWLY MONDAY AFTERNOON AS WEAK WAA INFILTRATES FROM THE WEST IN
ADVANCE OF THE NEXT SHORTWAVE TROUGH.
LONG TERM...12Z TUESDAY AND BEYOND. THE NEXT WAVE PASSES THROUGH
EARLY TUESDAY...HOWEVER MOISTURE REMAINS IN QUESTION...AND KINEMATIC
FORCING REMAINS SOMEWHAT WEAK AND TO THE SOUTH...THUS CONFIDENCE IS
TOO LOW TO INTRODUCE POPS INTO THE FORECAST. OTHERWISE SHORTWAVE
RIDGING AND WAA TAKE HOLD THROUGH THE END OF NEXT WEEK...WITH
TEMPERATURES REMAINING NEAR TO SLIGHTLY ABOVE SEASONAL NORMS. THE
NEXT SIGNIFICANT TROUGH IS SHOWN TO ARRIVE ACROSS THE WEST LATE NEXT
WEEK...BUT WITH THIS EVENINGS MODEL RUNS...PRECIPITATION CHANCES
LOOK TO REMAIN WELL TO THE SOUTH AND WEST OF THE CWA.
&&
.AVIATION...
MVFR/LOCAL IFR CIGS ARE EXPECTED IN SOME AREAS TODAY AND TONIGHT.
THE RUC MODEL...WHICH HAS BEEN PERFORMING WELL...SHOWS THE MVFR/IFR
CIGS ACROSS NCNTL NEB LIFTING NORTH THIS AFTERNOON WITH MVFR CIGS
FILLING IN AGAIN AS AN ARCTIC FRONT MOVES INTO WRN/NCNTL NEB TONIGHT.
MEANWHILE A WARM FRONT DEVELOPING ACROSS SRN NEB THIS MORNING WILL
LIFT NORTH DURING THE DAY TODAY PRODUCING ISOLATED RAIN AND SNOW
SHOWERS AND LOCAL MVFR CIGS. ADDITIONAL SCATTERED SNOW SHOWERS/MVFR
CIGS ARE EXPECTED TONIGHT ALONG AND BEHIND THE ARCTIC FRONT.
WINDS ALONG AND BEHIND THE FRONT WILL INCREASE TO 32025G35KT TONIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...JACOBS
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
801 AM EST SAT DEC 8 2012
.SYNOPSIS...
WARMING SOUTHWEST FLOW WILL BE FEATURED ACROSS THE REGION THIS
WEEKEND. SHOWER CHANCES ARE EXPECTED TO INCREASE BY MONDAY OUT AHEAD
OF AN APPROACHING COLD FRONT. HIGH PRESSURE MOVE BACKS IN FOR MID
WEEK WITH COOLER TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 745 AM...SEVERAL METARS ACRS THE NC FOOTHILLS AND NW PIEDMONT
WERE STILL REPORTING VSBY OF 1/4 OR LESS. THE 12Z GSO SNDG SHOWS
STRONG INVERSION ABOVE THE FOG/STRATUS LAYER...WHILE IR SATELLITE
SHOWS PLENTY OF THICK CIRRUS STREAMING ACRS THE AREA. SO I THINK THE
FOG WILL BE A BIT SLOW TO LIFT...AND HENCE HAVE EXTENDED THE DENSE
FOG ADV UNTIL 10 AM. OTHERWISE...NO CHANGES.
630 AM UPDATE...06Z NAM INDICATING SOMEWHAT MORE UNSTABLE ATMOSPHERE
THIS AFTERNOON...PARTICULARLY IN THE MTNS WHERE MUCAPE VALUES NEAR
300 J/KG ARE SEEN ON PROG SOUNDINGS. FORCING STILL NOT ALL THAT
IMPRESSIVE AND HAVE MAINTAINED SLIGHT CHANCE TO LOW CHANCE POPS.
TSTM CHANCES STILL LOW ENOUGH THAT NO MENTION NEEDED IN FCST.
AS OF 300 AM SAT...DENSE FOG BEING OBSERVED ACROSS PARTS OF THE
CWFA...MAINLY THE NC FOOTHILLS...BUT ALSO AT SOME SITES IN THE LOWER
SC PIEDMONT. CONDITIONS HAVE BEEN SOMEWHAT STABLE FOR A COUPLE OF
HOURS NOW AND SOME SITES HAVE ALREADY SEEN DENSE FOG DEVELOP AND
THEN THIN OUT. THIS IS BELIEVED TO HAVE HAPPENED DUE TO SETTLING OF
FOG DROPLETS AS THE TOP OF THE FOG LAYER IS KEPT WARMER BY HIGHER
CLOUDS PASSING OVERHEAD. SOME DRYING WAS INDICATED ON RAP LOW LEVEL
RH AND PROG SOUNDINGS AND THIS COULD HAVE ALSO CONTRIBUTED.
NONETHELESS...A DENSE FOG ADVISORY HAS BEEN ISSUED FOR THE NC
FOOTHILLS AREA WHERE VISIBILITIES HAVE REMAINED LOW IN A CONTIGUOUS
AREA. RAPID IMPROVEMENT IS EXPECTED AFTER SUNRISE.
WEAK HIGH PRESSURE REMAINS OVER THE SOUTH ATLANTIC COAST THROUGH THE
PERIOD...MAINTAINING SOUTHWESTERLY LOW TO MID LEVEL FLOW ACROSS THE
CWFA. MOISTURE IN TERMS OF 850MB DEWPOINTS AND 850-700MB RH
INCREASES AS A RESULT. ISENTROPIC VERTICAL MOTION IS GENERALLY
NEUTRAL WITH ONLY GRADUAL INCREASES IN 850MB TEMPS NOTED. THE FLOW
IS SOMEWHAT UPSLOPING BUT THE SOUTHWEST ORIENTATION IS ONLY LIKELY
TO PRODUCE POPS OVER OUR SOUTHWEST MTNS. THIS LOOKS TO BE THE BEST
AVAILABLE FORCING DURING THE DAY SATURDAY. THE GFS POP EVOLUTION
SEEMED TO BEST REFLECT THAT SO I BASED TRENDS ON IT DURING THAT
TIME. HIGHEST POPS LOOK TO BE AFTER 00Z SUN AS POCKET OF MIDLEVEL Q
VECTOR CONVERGENCE MOVES NORTHWARD ACROSS THE CWFA WHILE MOISTURE
CONTINUES TO STREAM IN.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 245 AM SATURDAY...THE MAIN FOCUS FOR THE SHORT RANGE WILL BE
THE PASSAGE OF A COLD FRONT LATE IN THE PERIOD. FOR SUNDAY AND
SUNDAY NIGHT...WE WILL CONTINUE TO HAVE TO DEAL WITH THE UNCERTAIN
BEGINNINGS OF PRE-FRONTAL SHOWER ACTIVITY. LOW LEVEL FORCING AND
MOISTURE LOOK ADEQUATE AS THEY HAVE FOR THE LAST FEW MODEL RUNS...
AND THE GFS/NAM SHOW A WEAK UPPER WAVE MOVING OVERHEAD IN THE
STRENGTHENING SW FLOW ALOFT. THAT SHOULD BE ENOUGH TO JUSTIFY
CARRYING A LOW END 20-30 PRECIP CHANCE TO ACCOUNT FOR SOME SCATTERED
LIGHT SHOWER ACTIVITY AND TO MATCH THE FCST FROM NEIGHBORING
OFFICES. DO NOT EXPECT THIS TO AMOUNT TO MUCH. TEMPS SUNDAY ARE
STILL A BIT PROBLEMATIC...ALTHO WE ARE LESS LIKELY TO BE BOTHERED
WITH ANY LINGERING COOL POOL AND WARM ADVECTION SHOULD ALLOW FOR
U60S/L70S OUTSIDE THE MTNS IN SPITE OF CLOUD COVER. EXPECT SUNDAY
NIGHT TO BE QUITE MILD FOR DECEMBER.
WHICH BRINGS US TO MONDAY. THERE HAS BEEN DISAGREEMENT AMONG MODEL
SOLUTIONS AS TO THE TIMING OF THE FRONTAL PASSAGE EVER SINCE THIS
EVENT CAME ONTO THE HORIZON...BUT NOW THE OPERATIONAL RUNS SEEM TO
BE IN BETTER AGREEMENT WITH A FOCUS ON LATE MONDAY OR EARLY TUESDAY
MORNING. THE MODELS SHOW AN EXCELLENT SWATH OF FORCING AND DEEP
MOISTURE APPROACHING FROM THE WEST EARLY MONDAY. THE PROBLEM IS THAT
THIS THING MAY BE WEAKENING THE WHOLE WAY AS IT MOVES IN...AS THE
MAIN SHORT WAVE LIFTS PAST TO THE NW AND THE BEST UPPER DIVERGENCE
DOES THE SAME. LOW LEVEL FORCING SHOULD CARRY A PRECIP BAND INTO THE
NC MTNS BY THE AFTERNOON...SO A LIKELY POP IS STILL WARRANTED AS IN
THE RECENT MOSGUIDE. HAVE EXTENDED THE LOW END LIKELY EAST ACROSS
THE FOOTHILLS AND PIEDMONT LATE IN THE DAY ON THE STRENGTH OF THE
LOW LEVEL FORCING. THE BIG QUESTION IS THE SEVERE WEATHER POTENTIAL.
CONFIDENCE IS GREATER IN THE POTENTIAL FOR STRONG SHEAR AS A LOW
LEVEL JET MOVES NE AHEAD OF THE FRONT ON MONDAY. IF THE GFS IS
CORRECT...THE PIEDMONT OF THE CAROLINAS WILL SEE ENOUGH BUOYANCY
THAT WE WILL HAVE TO WORRY ABOUT WIND DAMAGE AND PERHAPS AN ISOLATED
BRIEF TORNADO IF THE CONVECTIVE MODE IS LINEAR. THAT REMAINS A BIG
IF. THE NAM LIMITS THE POTENTIAL TO NE GEORGIA AND UPSTATE SC S AND
E OF I-85. THE ECMWF IS NOT IMPRESSED. WILL NOT TALK THIS UP IN THE
HWO JUST YET...BUT WILL KEEP IT SIMMERING ON A BACK BURNER. WILL
HOWEVER CONTINUE TO MENTION SOME THUNDER MONDAY AFTERNOON AND
EVENING OVER THE EASTERN ZONES. PRECIP CHANCES GRADUALLY DIMINISH
MONDAY NIGHT AS THE FRONT WEAKENS E OF THE FCST AREA.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AT 230 AM EST SATURDAY...A BROAD AND FAIRLY DEEP TROUGH WILL BE OVER
THE CENTER OF NORTH AMERICA ON TUESDAY. THIS TROUGH DEAMPLIFIES ON
WEDNESDAY...WHILE ANOTHER TROUGH AMPLIFIES ALONG THE WEST COAST. A
FAST MOVING SHORTWAVE OVER TEXAS WEDNESDAY AFTERNOON WILL REACH OUR
REGION THURSDAY WITH SURFACE LOW PRESSURE GENERATED IN THE GULF
BEING PULLED ACROSS FLORIDA TO THE CAROLINA COAST. THE GFS IS A BIT
FASTER WITH THIS SHORTWAVE THAN THE ECMWF.
WITH THE FASTER PROGRESSION OF THE GFS...ALL PRECIP HAD ENDED OVER
THE WESTERN CAROLINAS BY 12Z TUESDAY. HIGH PRESSURE CENTERED OVER
THE TENNESSEE AND OHIO VALLEYS THROUGH MID WEEK PROVIDING DRY
WEATHER FOR OUR REGION AS THE FRONT LINGERS OVER FLORIDA. THE
CURRENT GFS RUN HAS THE 500MB SHORTWAVE REACHING GEORGIA AT 12Z
THURSDAY WITH SOME RAIN SPREADING OVER NE GA AND THE UPSTATE. ALL
PRECIP IS WELL EAST OF I-77 BY 00Z FRIDAY. THE GFS HAS THE CHARLOTTE
AREA GETTING NEAR A HALF INCH OF RAIN AND EVEN MORE NEAR MARSHVILLE.
SURFACE HIGH CENTERED OVER THE CAROLINAS AND VIRGINIA FOR FRIDAY ON
THE GFS. THE NEXT SYSTEM WILL BE CROSSING TENNESSEE BY 12Z SATURDAY.
THE NEW ECMWF HAS THE COLD FRONT CROSSING OUR AREA AT 12Z TUESDAY
WITH THE RAIN GRADUALLY ENDING EAST OF CHARLOTTE AROUND SUNSET. THE
HIGH IS ALIGNED ROUGHLY THE SAME ON WEDNESDAY AS ON THE GFS WITH THE
FRONT LINGERING ACROSS FLORIDA. THE SHARP 500MB SHORTWAVE WILL BE
OVER THE MISSISSIPPI RIVER 00Z THURSDAY AND OVER WESTERN GEORGIA AT
12Z THURSDAY AND DEEPER THAN THE GFS AT THAT TIME. THE BIG
DIFFERENCE IN THE PRECIP SHIELD IS THAT LITTLE IF ANY PRECIP REACHES
OUR PIEDMONT AS THE SHORTWAVE PASSES ON THURSDAY ACCORDING TO THE
ECMWF. THE NEXT SYSTEM WILL BE CROSSING TENNESSEE BY 12Z SATURDAY AS
WELL BUT SOME PRECIP REACHING THE WESTERN MOUNTAINS EARLY SATURDAY.
TEMPERATURES NEAR NORMAL THROUGH THE MEDIUM RANGE.
&&
.AVIATION /13Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...LIFR CIGS AND MVFR VSBY SHOULD PERSIST FOR AN HOUR OR TWO
AFTER SUNRISE UNTIL DIURNAL HEATING CAN BEGIN THE EVAPORATION
PROCESS. THE LIGHT FOG SHOULD QUICKLY DISSIPATE BUT IT WILL LIKELY
TAKE A COUPLE OF HOURS FOR THE LOW CIG TO BREAK UP OR LIFT. MOISTURE
WILL STILL BE PRESENT AT A HIGHER LEVEL...SO A VFR CIG WILL HOLD ON
FOR MOST OF THE DAY...WITH POSSIBLE BREAKS IN THE AFTERNOON.
GUIDANCE INDICATES SOME FOG POTENTIAL FOR LATE TONIGHT/EARLY SUNDAY
GIVEN HIGH SURFACE RH VALUES. AT THIS TIME...WILL MENTION MVFR VSBY
NEAR THE END OF THE PERIOD. SFC HIGH PRESSURE ALONG THE COAST WILL
MAINTAIN SOUTHWEST WINDS THROUGH THE PERIOD...LESS THAN 10KT.
ELSEWHERE...LIFR TO IFR CIGS SEEN ACROSS PARTS OF THE AREA WITH
BREAKS IN LOW CLOUDS EVIDENT ON SFC OBS. THE CIGS ARE EXPECTED TO
SEE SOME IMPROVEMENT IN THE FIRST COUPLE OF HOURS AFTER SUNRISE.
DENSE FOG OCCURRING OVER THE NC FOOTHILLS WILL SLOWLY ERODE...WITH
RESTRICTIONS LIKELY DISAPPEARING BY MID MORNING. SLIGHT CHANCE FOR
PRECIP OVER THE MTNS TODAY...WITH CHANCES INCREASING OVERNIGHT...BUT
ACCUMULATION FROM ANY SHOWERS THAT FORM WILL BE VERY LIGHT AND
OPERATIONAL IMPACTS WILL BE VERY MINOR. GUIDANCE HINTS AT
POSSIBILITY OF FOG DEVELOPING BY 06Z SUN ACROSS MUCH OF THE AREA.
CONFIDENCE LOW AS TO JUST HOW DENSE IT WOULD BE...SO HAVE KEPT ONLY
MVFR MENTION IN TAFS.
OUTLOOK...VFR CONDITIONS ARE EXPECTED OVERALL THRU THE WEEKEND...BUT
PATCHY FOG AND STRATUS WILL BE POSSIBLE BOTH SUNDAY AND MONDAY
MORNINGS. A STRONG COLD FRONT WILL CROSS THE REGION MONDAY OR MONDAY
NIGHT...ACCOMPANIED BY SHOWERS AND THUNDERSTORMS ALONG WITH GUSTY
WINDS.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR NCZ035-036-
056-068-069-501>510.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...ARK/WIMBERLEY
SHORT TERM...PM
LONG TERM...DEO
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
651 AM EST SAT DEC 8 2012
.SYNOPSIS...
WARMING SOUTHWEST FLOW WILL BE FEATURED ACROSS THE REGION THIS
WEEKEND. SHOWER CHANCES ARE EXPECTED TO INCREASE BY MONDAY OUT AHEAD
OF AN APPROACHING COLD FRONT. HIGH PRESSURE MOVE BACKS IN FOR MID
WEEK WITH COOLER TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
630 AM UPDATE...06Z NAM INDICATING SOMEWHAT MORE UNSTABLE ATMOSPHERE
THIS AFTERNOON...PARTICULARLY IN THE MTNS WHERE MUCAPE VALUES NEAR
300 J/KG ARE SEEN ON PROG SOUNDINGS. FORCING STILL NOT ALL THAT
IMPRESSIVE AND HAVE MAINTAINED SLIGHT CHANCE TO LOW CHANCE POPS.
TSTM CHANCES STILL LOW ENOUGH THAT NO MENTION NEEDED IN FCST.
AS OF 300 AM SAT...DENSE FOG BEING OBSERVED ACROSS PARTS OF THE
CWFA...MAINLY THE NC FOOTHILLS...BUT ALSO AT SOME SITES IN THE LOWER
SC PIEDMONT. CONDITIONS HAVE BEEN SOMEWHAT STABLE FOR A COUPLE OF
HOURS NOW AND SOME SITES HAVE ALREADY SEEN DENSE FOG DEVELOP AND
THEN THIN OUT. THIS IS BELIEVED TO HAVE HAPPENED DUE TO SETTLING OF
FOG DROPLETS AS THE TOP OF THE FOG LAYER IS KEPT WARMER BY HIGHER
CLOUDS PASSING OVERHEAD. SOME DRYING WAS INDICATED ON RAP LOW LEVEL
RH AND PROG SOUNDINGS AND THIS COULD HAVE ALSO CONTRIBUTED.
NONETHELESS...A DENSE FOG ADVISORY HAS BEEN ISSUED FOR THE NC
FOOTHILLS AREA WHERE VISIBILITIES HAVE REMAINED LOW IN A CONTIGUOUS
AREA. RAPID IMPROVEMENT IS EXPECTED AFTER SUNRISE.
WEAK HIGH PRESSURE REMAINS OVER THE SOUTH ATLANTIC COAST THROUGH THE
PERIOD...MAINTAINING SOUTHWESTERLY LOW TO MID LEVEL FLOW ACROSS THE
CWFA. MOISTURE IN TERMS OF 850MB DEWPOINTS AND 850-700MB RH
INCREASES AS A RESULT. ISENTROPIC VERTICAL MOTION IS GENERALLY
NEUTRAL WITH ONLY GRADUAL INCREASES IN 850MB TEMPS NOTED. THE FLOW
IS SOMEWHAT UPSLOPING BUT THE SOUTHWEST ORIENTATION IS ONLY LIKELY
TO PRODUCE POPS OVER OUR SOUTHWEST MTNS. THIS LOOKS TO BE THE BEST
AVAILABLE FORCING DURING THE DAY SATURDAY. THE GFS POP EVOLUTION
SEEMED TO BEST REFLECT THAT SO I BASED TRENDS ON IT DURING THAT
TIME. HIGHEST POPS LOOK TO BE AFTER 00Z SUN AS POCKET OF MIDLEVEL Q
VECTOR CONVERGENCE MOVES NORTHWARD ACROSS THE CWFA WHILE MOISTURE
CONTINUES TO STREAM IN.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 245 AM SATURDAY...THE MAIN FOCUS FOR THE SHORT RANGE WILL BE
THE PASSAGE OF A COLD FRONT LATE IN THE PERIOD. FOR SUNDAY AND
SUNDAY NIGHT...WE WILL CONTINUE TO HAVE TO DEAL WITH THE UNCERTAIN
BEGINNINGS OF PRE-FRONTAL SHOWER ACTIVITY. LOW LEVEL FORCING AND
MOISTURE LOOK ADEQUATE AS THEY HAVE FOR THE LAST FEW MODEL RUNS...
AND THE GFS/NAM SHOW A WEAK UPPER WAVE MOVING OVERHEAD IN THE
STRENGTHENING SW FLOW ALOFT. THAT SHOULD BE ENOUGH TO JUSTIFY
CARRYING A LOW END 20-30 PRECIP CHANCE TO ACCOUNT FOR SOME SCATTERED
LIGHT SHOWER ACTIVITY AND TO MATCH THE FCST FROM NEIGHBORING
OFFICES. DO NOT EXPECT THIS TO AMOUNT TO MUCH. TEMPS SUNDAY ARE
STILL A BIT PROBLEMATIC...ALTHO WE ARE LESS LIKELY TO BE BOTHERED
WITH ANY LINGERING COOL POOL AND WARM ADVECTION SHOULD ALLOW FOR
U60S/L70S OUTSIDE THE MTNS IN SPITE OF CLOUD COVER. EXPECT SUNDAY
NIGHT TO BE QUITE MILD FOR DECEMBER.
WHICH BRINGS US TO MONDAY. THERE HAS BEEN DISAGREEMENT AMONG MODEL
SOLUTIONS AS TO THE TIMING OF THE FRONTAL PASSAGE EVER SINCE THIS
EVENT CAME ONTO THE HORIZON...BUT NOW THE OPERATIONAL RUNS SEEM TO
BE IN BETTER AGREEMENT WITH A FOCUS ON LATE MONDAY OR EARLY TUESDAY
MORNING. THE MODELS SHOW AN EXCELLENT SWATH OF FORCING AND DEEP
MOISTURE APPROACHING FROM THE WEST EARLY MONDAY. THE PROBLEM IS THAT
THIS THING MAY BE WEAKENING THE WHOLE WAY AS IT MOVES IN...AS THE
MAIN SHORT WAVE LIFTS PAST TO THE NW AND THE BEST UPPER DIVERGENCE
DOES THE SAME. LOW LEVEL FORCING SHOULD CARRY A PRECIP BAND INTO THE
NC MTNS BY THE AFTERNOON...SO A LIKELY POP IS STILL WARRANTED AS IN
THE RECENT MOSGUIDE. HAVE EXTENDED THE LOW END LIKELY EAST ACROSS
THE FOOTHILLS AND PIEDMONT LATE IN THE DAY ON THE STRENGTH OF THE
LOW LEVEL FORCING. THE BIG QUESTION IS THE SEVERE WEATHER POTENTIAL.
CONFIDENCE IS GREATER IN THE POTENTIAL FOR STRONG SHEAR AS A LOW
LEVEL JET MOVES NE AHEAD OF THE FRONT ON MONDAY. IF THE GFS IS
CORRECT...THE PIEDMONT OF THE CAROLINAS WILL SEE ENOUGH BUOYANCY
THAT WE WILL HAVE TO WORRY ABOUT WIND DAMAGE AND PERHAPS AN ISOLATED
BRIEF TORNADO IF THE CONVECTIVE MODE IS LINEAR. THAT REMAINS A BIG
IF. THE NAM LIMITS THE POTENTIAL TO NE GEORGIA AND UPSTATE SC S AND
E OF I-85. THE ECMWF IS NOT IMPRESSED. WILL NOT TALK THIS UP IN THE
HWO JUST YET...BUT WILL KEEP IT SIMMERING ON A BACK BURNER. WILL
HOWEVER CONTINUE TO MENTION SOME THUNDER MONDAY AFTERNOON AND
EVENING OVER THE EASTERN ZONES. PRECIP CHANCES GRADUALLY DIMINISH
MONDAY NIGHT AS THE FRONT WEAKENS E OF THE FCST AREA.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AT 230 AM EST SATURDAY...A BROAD AND FAIRLY DEEP TROUGH WILL BE OVER
THE CENTER OF NORTH AMERICA ON TUESDAY. THIS TROUGH DEAMPLIFIES ON
WEDNESDAY...WHILE ANOTHER TROUGH AMPLIFIES ALONG THE WEST COAST. A
FAST MOVING SHORTWAVE OVER TEXAS WEDNESDAY AFTERNOON WILL REACH OUR
REGION THURSDAY WITH SURFACE LOW PRESSURE GENERATED IN THE GULF
BEING PULLED ACROSS FLORIDA TO THE CAROLINA COAST. THE GFS IS A BIT
FASTER WITH THIS SHORTWAVE THAN THE ECMWF.
WITH THE FASTER PROGRESSION OF THE GFS...ALL PRECIP HAD ENDED OVER
THE WESTERN CAROLINAS BY 12Z TUESDAY. HIGH PRESSURE CENTERED OVER
THE TENNESSEE AND OHIO VALLEYS THROUGH MID WEEK PROVIDING DRY
WEATHER FOR OUR REGION AS THE FRONT LINGERS OVER FLORIDA. THE
CURRENT GFS RUN HAS THE 500MB SHORTWAVE REACHING GEORGIA AT 12Z
THURSDAY WITH SOME RAIN SPREADING OVER NE GA AND THE UPSTATE. ALL
PRECIP IS WELL EAST OF I-77 BY 00Z FRIDAY. THE GFS HAS THE CHARLOTTE
AREA GETTING NEAR A HALF INCH OF RAIN AND EVEN MORE NEAR MARSHVILLE.
SURFACE HIGH CENTERED OVER THE CAROLINAS AND VIRGINIA FOR FRIDAY ON
THE GFS. THE NEXT SYSTEM WILL BE CROSSING TENNESSEE BY 12Z SATURDAY.
THE NEW ECMWF HAS THE COLD FRONT CROSSING OUR AREA AT 12Z TUESDAY
WITH THE RAIN GRADUALLY ENDING EAST OF CHARLOTTE AROUND SUNSET. THE
HIGH IS ALIGNED ROUGHLY THE SAME ON WEDNESDAY AS ON THE GFS WITH THE
FRONT LINGERING ACROSS FLORIDA. THE SHARP 500MB SHORTWAVE WILL BE
OVER THE MISSISSIPPI RIVER 00Z THURSDAY AND OVER WESTERN GEORGIA AT
12Z THURSDAY AND DEEPER THAN THE GFS AT THAT TIME. THE BIG
DIFFERENCE IN THE PRECIP SHIELD IS THAT LITTLE IF ANY PRECIP REACHES
OUR PIEDMONT AS THE SHORTWAVE PASSES ON THURSDAY ACCORDING TO THE
ECMWF. THE NEXT SYSTEM WILL BE CROSSING TENNESSEE BY 12Z SATURDAY AS
WELL BUT SOME PRECIP REACHING THE WESTERN MOUNTAINS EARLY SATURDAY.
TEMPERATURES NEAR NORMAL THROUGH THE MEDIUM RANGE.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...LIFR CIGS AND MVFR VSBY SHOULD PERSIST FOR AN HOUR OR TWO
AFTER SUNRISE UNTIL DIURNAL HEATING CAN BEGIN THE EVAPORATION
PROCESS. THE LIGHT FOG SHOULD QUICKLY DISSIPATE BUT IT WILL LIKELY
TAKE A COUPLE OF HOURS FOR THE LOW CIG TO BREAK UP OR LIFT. MOISTURE
WILL STILL BE PRESENT AT A HIGHER LEVEL...SO A VFR CIG WILL HOLD ON
FOR MOST OF THE DAY...WITH POSSIBLE BREAKS IN THE AFTERNOON.
GUIDANCE INDICATES SOME FOG POTENTIAL FOR LATE TONIGHT/EARLY SUNDAY
GIVEN HIGH SURFACE RH VALUES. AT THIS TIME...WILL MENTION MVFR VSBY
NEAR THE END OF THE PERIOD. SFC HIGH PRESSURE ALONG THE COAST WILL
MAINTAIN SOUTHWEST WINDS THROUGH THE PERIOD...LESS THAN 10KT.
ELSEWHERE...LIFR TO IFR CIGS SEEN ACROSS PARTS OF THE AREA WITH
BREAKS IN LOW CLOUDS EVIDENT ON SFC OBS. THE CIGS ARE EXPECTED TO
SEE SOME IMPROVEMENT IN THE FIRST COUPLE OF HOURS AFTER SUNRISE.
DENSE FOG OCCURRING OVER THE NC FOOTHILLS WILL SLOWLY ERODE...WITH
RESTRICTIONS LIKELY DISAPPEARING BY MID MORNING. SLIGHT CHANCE FOR
PRECIP OVER THE MTNS TODAY...WITH CHANCES INCREASING OVERNIGHT...BUT
ACCUMULATION FROM ANY SHOWERS THAT FORM WILL BE VERY LIGHT AND
OPERATIONAL IMPACTS WILL BE VERY MINOR. GUIDANCE HINTS AT
POSSIBILITY OF FOG DEVELOPING BY 06Z SUN ACROSS MUCH OF THE AREA.
CONFIDENCE LOW AS TO JUST HOW DENSE IT WOULD BE...SO HAVE KEPT ONLY
MVFR MENTION IN TAFS.
OUTLOOK...VFR CONDITIONS ARE EXPECTED OVERALL THRU THE WEEKEND...BUT
PATCHY FOG AND STRATUS WILL BE POSSIBLE BOTH SUNDAY AND MONDAY
MORNINGS. A STRONG COLD FRONT WILL CROSS THE REGION MONDAY OR MONDAY
NIGHT...ACCOMPANIED BY SHOWERS AND THUNDERSTORMS ALONG WITH GUSTY
WINDS.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...DENSE FOG ADVISORY UNTIL 8 AM EST THIS MORNING FOR NCZ035-036-
056-068-069-501>510.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...WIMBERLEY
SHORT TERM...PM
LONG TERM...DEO
AVIATION...WIMBERLEY
AREA FORECAST DISCUSSION
NWS WICHITA KS
1128 AM CST SAT DEC 8 2012
.UPDATE...
THE FORECAST WAS UPDATED TO INCREASE CLOUD COVER AS THE LATEST
VISIBLE SATELLITE TREND SUPPORTS THE HRRR WITH WIDESPREAD LOW
CEILINGS OVERSPREADING THE AREA TODAY. THIS MAY ALSO IMPACT
HIGH TEMPERATURES...ALTHOUGH UPPER 40S WILL LIKELY BE REACHED EVEN WITH
LIMITED INSOLATION THROUGH THE AFTERNOON HOURS.
MWM
&&
.AVIATION...18Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
TRENDED FLIGHT CATEGORIES DOWN THIS AFTERNOON AND TONIGHT AS LOW
LEVEL ISENTROPIC UPGLIDE WILL SUPPORT WIDESPREAD MVFR/AREAS OF IFR
CIGS THROUGH THE AFTERNOON AND TONIGHT. AS THE COLD FRONT
ARRIVES AFTER 06Z ACROSS CENTRAL KANSAS...CEILINGS WILL BEGIN TO LIFT
WITH MVFR/VFR PREVAILING ONCE AGAIN. WINDS BEHIND THE FRONT WILL
INCREASE TO 20-30 KNOTS WITH LIGHT SNOW DEVELOPING ACROSS PORTIONS
OF CENTRAL KANSAS ON SUNDAY.
MWM
&&
.PREV DISCUSSION... /ISSUED 534 AM CST SAT DEC 8 2012/
AVIATION...12Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
THE MAIN AVIATION FORECAST CONCERN IS MVFR/IFR CONDITIONS IN THE
NEAR TERM...AND GUSTY NORTHWEST WINDS AFTER THE FRONTAL PASSAGE
TONIGHT AND AGAIN MVFR/IFR CONDITIONS BEHIND THE FRONT.
SURFACE HIGH PRESSURE WILL SLIDE OVERHEAD TODAY WITH LIGHT WINDS
BECOMING SOUTHERLY FROM WEST TO EAST. MVFR/IFR CONDITIONS AT KCNU
THIS MORNING ARE EXPECTED TO IMPROVE TO VFR BY LATE MORNING. THE
NEXT POTENT COLD FRONT WILL MOVE ACROSS THE AREA
OVERNIGHT...IMPACTING KRSL/KSLN AROUND 06-07Z...KICT/KHUT AROUND
08-09Z AND KCNU JUST TOWARD THE END OF THE TAF PERIOD. WINDS WILL
BECOME NORTH-NORTHWESTERLY BUT THE STRONGEST WINDS WILL LAG JUST A
BIT BEHIND THE INITIAL WIND SHIFT. SOME LOW CLOUDS ARE ALSO
EXPECTED AS THE FRONT MOVES IN WITH MVFR CONDITIONS FORECASTED AT
KRSL AND KSLN JUST PRIOR TO 12Z SUNDAY MORNING. HAVE LEFT
PRECIPITATION CHANCES OUT AT THIS TIME...WITH LOW CONFIDENCE THIS
MORNING...WILL WAIT UNTIL LATER FORECASTS HAVE A BETTER HANDLE ON
HOW PRECIP WILL IMPACT THE TERMINALS.
BILLINGS
PREV DISCUSSION... /ISSUED 332 AM CST SAT DEC 8 2012/
DISCUSSION...
TODAY:
MAIN CHALLENGE WILL BE IF LOW CLOUDS IN SOUTHEAST KS WILL BREAK
BEFORE RETURNING BACK NORTH LATER TODAY. CLOUDS ARE EXPECTED TO
INCREASE ACROSS MOST OF THE AREA LATER TODAY.
TONIGHT-SUN NIGHT:
MODELS HAVE COME INTO BETTER AGREEMENT...BUT LIMITED MOISTURE AND
POOR PHASING OF DYNAMICS WILL LIKELY PRECLUDE ANY SIGNIFICANT QPF.
BRIEF PERIOD OF ISENTROPIC LIFT MAY LEAD TO SOME LIGHT RAIN THIS
EVENING NEAR LEADING EDGE OF LOW LEVEL MOISTURE. AS 850MB WINDS
VEER...LIFT WILL DECREASE PRIOR TO ARRIVAL OF FRONT. THE FRONT SHOULD
ENTER FAR NORTHWEST SECTIONS OF FORECAST AREA AROUND 06Z AND RACE
SOUTHEAST AND EXIT AREA AROUND 1200 UTC. COMBO OF NEAR ADVISORY
LEVEL WINDS WILL AID COLD AIR ADVECTION RESULTING IN STEADY TO
SLOWLY FALLING TEMPERATURES AT MOST LOCATIONS. PRECIPITATION
CHANCES WILL INCREASE SLIGHTLY THROUGH THE DAY WITH THE
PREDOMINATE WEATHER TYPE EXPECTED TO BE FLURRIES. THIS IS DUE TO
LACK OF INSTABILITY IN SNOW GROWTH ZONE AND INFLUX OF LOW LEVEL
DRY AIR THROUGHOUT THE PERIOD. WILL HANG ONTO FLURRIES UNTIL
MIDNIGHT AS MID LEVEL BAND OF MOISTURE MOVES THROUGH. VERY DRY
AIR AND DIMINISHING WINDS/LACK OF PRECIPITATION WILL LIKELY ALLOW
FOR SINGLE DIGIT LOWS SOUTH ACROSS CENTRAL KS SUN NIGHT.
MON-FRI:
AFTER VERY CHILLY START TO MONDAY...EXPECT A GRADUAL MODERATION OF
THE COLD AIRMASS. SHORTWAVE MOVING THROUGH MIDWEEK WILL LIKELY BE
MOISTURE STARVED AND FRONT WILL COME THROUGH DRY. SLIGHTLY BETTER
CHANCE FOR PRECIPITATION ON FRI AS DECENT SHORTWAVE MOVES OUT OF
SOUTHWEST US WITH APPARENTLY GOOD SURFACE CYCLOGENESIS. -HOWERTON
AVIATION...06Z TAFS KRSL/KSLN/KHUT/KICT/KCNU
AREAS CONTINUING CAUSE FOR CONCERN ARE GENERALLY ALONG & SE OF TURNPIKE
WHERE WIDESPREAD 1,200-1,500FT CIGS PERSIST WHILE IFR DECKS CONTINUE TO
PESTER EXTREME SE KS WHERE VERY CLOSE TO A WEAK SE DRIFTING COLD FRONT.
THE SE PROGRESS OF THE COLD FRONT WILL NEED TO BE WATCHED CLOSELY. FOR
NOW IT APPEARS THE FRONT MIGHT MAKE SUFFICIENT PROGRESS FOR IFR CIGS TO
REMAIN E-S OF KCNU...HOWEVER MVFR VSBYS ARE LIKELY OVER KCNU THROUGH
~15Z. PER SATELLITE IMAGERY KICT REMAINS SITUATED ALONG WRN PERIPHERY
OF "LOW-END" MVFR STRATUS & WITH WEAK HIGH PRESSURE CONTINUING TO DRIFT
E EXPECT THE TERMINAL TO REALIZE VFR STATUS ~09Z BUT THIS TOO WILL NEED
TO BE WATCHED CLOSELY.
ES
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 49 31 39 14 / 10 10 10 10
HUTCHINSON 48 28 37 12 / 10 10 10 10
NEWTON 48 31 37 12 / 10 10 10 10
ELDORADO 49 32 39 14 / 10 10 10 10
WINFIELD-KWLD 50 33 41 14 / 10 10 20 10
RUSSELL 48 27 33 6 / 0 20 10 10
GREAT BEND 48 28 34 7 / 10 10 10 10
SALINA 48 28 35 12 / 10 20 10 10
MCPHERSON 48 29 36 12 / 10 20 10 10
COFFEYVILLE 50 42 45 19 / 10 10 20 10
CHANUTE 50 38 42 15 / 10 10 20 10
IOLA 50 37 42 15 / 10 10 20 10
PARSONS-KPPF 50 40 44 16 / 10 10 20 10
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CARIBOU ME
516 PM EST SAT DEC 8 2012
.SYNOPSIS...
A WEAK WAVE OF LOW PRESSURE WILL CROSS THE REGION THIS EVENING
BEFORE MOVING OUT OVERNIGHT. HIGH PRESSURE WILL CROSS THE REGION
SUNDAY. LOW PRESSURE WILL THEN CROSS THE REGION MONDAY.
&&
.NEAR TERM /THROUGH SUNDAY/...
510 PM UPDATE...
ADDED THE MENTION OF FZRA INTO NORTHERN AND WEST-CENTRAL ZONES
TONIGHT AS THE LATEST RUC AND NAM SOUNDINGS INDICATE SFC
TEMPERATURES FALLING BACK W/WARM FROM 1K TO 4K FT INDICATING THE
POTENTIAL FOR FREEZING PRECIP. RAIN IN THE HOULTON AND MILLINOCKET
REGION BUT COULD VERY WELL SEE FREEZING PRECIP IN THESE AREAS
AFTER 8 PM. COULD NEED A WINTER WEATHER/FREEZING RAIN ADVISORY
TONIGHT. WILL ASSESS THIS FURTHER.
DOWNEAST AND COAST WILL STAY WARM ENOUGH FOR RAIN. HOWEVER, WE
WILL NEED MONITOR THE CENTRAL AREAS SUCH AS SOUTHERN PISCATAQUIS,
CENTRAL PENOBSCOT AND NORTHERN WASHINGTON COUNTIES AS WELL FOR THE
POTENTIAL FOR FZRA LATER TONIGHT.
PREVIOUS DISCUSSION...
A WEAK SYSTEM WILL CONTINUE TO AFFECT THE AREA INTO
TONIGHT. A SHIELD OF PRECIPITATION ASSOCIATED WITH A COASTAL WAVE
OF LOW PRESSURE CONTINUES TO AFFECT AREAS MAINLY SOUTH OF A PATTEN
TO HOULTON LINE. MOST OF THIS PRECIPITATION IS FALLING AS RAIN BUT
SOME SNOW OR SLEET WILL CONTINUE TO BE POSSIBLE ALONG THE NORTHERN
PERIPHERY OF THE PRECIPITATION SHIELD FOR PLACES LIKE MILLINOCKET.
THIS AREA OF RAIN/MIXED PRECIPITATION WILL DEPART FROM WEST TO
EAST THROUGH THE LATE AFTERNOON INTO THIS EVENING. MEANWHILE
ACROSS THE NORTH, PRECIPITATION ASSOCIATED WITH THE PRIMARY LOW
CURRENTLY LOCATED OVER NEW YORK STATE WILL BRUSH THE AREA THIS
EVENING. THIS PRECIPITATION WILL BE GENERALLY LIGHT AND LOOKS TO
FALL AS MAINLY SNOW IN ST JOHN VALLEY WITH A LITTLE RAIN OR PATCHY
FREEZING RAIN POTENTIALLY MIXING IN JUST TO THE SOUTH TOWARD THE
CARIBOU AREA. SINCE ANY FREEZING RAIN THAT OCCURS LOOKS TO BE
LIGHT AND PATCHY AN ADVISORY IS NOT WARRANTED AT THIS TIME. ALSO,
ANY SNOW ACCUMULATION LOOKS TO BE UNDER AN INCH AND CONFINED TO
AREAS MAINLY NORTH OF CARIBOU.
THE TWO LOWS WILL CONSOLIDATE TONIGHT AS THE SYSTEM MOVES EAST INTO
THE MARITIMES AND INTENSIFIES. STEADIER PRECIPITATION WILL TAPER
OFF BUT LINGERING FLURRIES AND SNOW SHOWERS WILL BE POSSIBLE IN THE
NORTH. IN ADDITION, WINDS WILL INCREASE.
SUNDAY WILL BE DRY AND BRIGHT BUT WINDY WITH NW WINDS GUSTING 20 TO
POTENTIALLY AS HIGH AS 30 MPH IN THE NORTH. THESE WINDS WILL ABATE
THROUGH THE AFTERNOON AS HIGH PRESSURE BRIEFLY MOVES IN. HIGHS
WILL RANGE FROM NEAR 30 IN THE NORTH TO AROUND 40 SOUTH.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
COLD ARCTIC LIKE SFC HI PRES OVR E CNTRL QB WILL BRING COLD DRY
CONDITIONS FOR SUN EVE. RIGHT ON THE HEELS OF THIS SYSTEM...LOW
PRES AND A SUPPORTING S/WV FROM THE GREAT LKS WILL BRING
INCREASING CLDNSS W TO E ACROSS THE FA OVRNGT SUN WITH LGT SNFL
FOLLOWING BEFORE THE DAYBREAK HRS ERLY MON MORN.
FOR THIS UPDATE...WE TOOK A SIG BLEND PTN WITH THE 12Z DTMNSTC ECMWF
FOR STORM TRACK ALG WITH HI/LOW TEMPS MON AND MON NGT. THE REASON
FOR GOING THIS DIRECTION IS THAT THE NAO TELECONNECTION PATTERN IS
FCST TO BECOME SIGNIFICANTLY NEGATIVE OVR THE NEXT FEW DAYS...MEANING
THAT BLOCKING NEAR GREENLAND IS NOT LIKELY TO ALLOW THE COLD SFC
HI PRES FROM EXITING LABRADOR DURING THIS UPCOMING EVENT...KEEPING
LLVL COLD AIR WELL ENTRENCHED ACROSS NRN PTNS OF THE FA.
IN DOING THIS WE TREND WITH A FURTHER S TRACK OF THE PRIMARY AND
TRIPLE POINT SECONDARY SFC LOW...MORE TOWARD CNTRL PTNS OF THE FA
RATHER THAN NRN PTNS. THIS FURTHER S TRACK WILL KEEP NRN PTNS OF
THE FA FROM CHGNG TO ALL RN IN THIS EVENT...WITH THE BEST
POTENTIAL OF PL AND FZRA OVR NRN AREAS DURG THE AFTN AND EVE HRS
OF MON. IN FACT...IF TDY`S 12Z ECMWF (SIMILAR TO LAST NGT`S 00Z
ECMWF) RUN IS CORRECT...THEN THE ST JOHN VLY OF XTRM NRN AROOSTOOK
COUNTY COULD RECEIVE ALL SN WITH THIS EVENT...HOWEVER...FOR THIS
UPDATE WE STILL INDICATE A FEW HRS OF MIX HERE VERY LATE MON INTO
ERLY MON EVE. FURTHER S...SNFL WILL NOT LAST AS LONG INTO MON AND
CHGOVR QUICKER TO PL AND FZRA AND THEN PLAIN RN WITH COASTAL AREAS
LEADING THE WAY. PRELIM TOTAL SNFL AND ICE WILL RANGE FROM 1 TO 2
INCHES AND UP TO A TENTH OF AN INCH RESPECTIVELY FOR DOWNEAST AND
CNTRL AREAS AND 2 TO 4 INCHES WITH ARND A TENTH OF AN INCH NRN
AREAS...WITH POSSIBLY A LITTLE MORE SN AND LESS ICE OVR THE ST
JOHN VLY.
MIXED PRECIP SHOULD TRANSITION BACK TO SN SHWRS ACROSS NRN AND
CNTRL PTNS OF THE FA OVRNGT MON. DOWNEAST AREAS WILL HOLD RAIN
LONGEST MON NGT...WITH S FEW MODELS INDICATING A VERY WEAK
TRAILING SFC WV ALG THE COLD FRONT WHICH MAY CONT SIG QPF IN THE
00-06Z TM FRAME. SFC TEMPS...WHICH WILL REACH A MAX LATE IN THE
DAY MON AND ERLY MON EVE WILL SLOWLY DROP OFF LATE MON NGT. WITH
CONTD LLVL COLD ADVCN ON TUE....HI TEMPS WILL ONLY MARGINALLY
RISE FROM ERLY MORN LOWS...WITH SHALLOW BKN-OVC LLVL COLD ADVCN
SC PERHAPS HOLDING ON OVR NRN PTNS OF THE FA.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A RATHER TRANQUIL WEATHER PATTERN CAN BE EXPECTED IN THE LONG TERM.
LOW PRESSURE WILL CONTINUE TO EXIT NORTHEAST OF THE CANADIAN
MARITIMES TUESDAY NIGHT. HIGH PRESSURE WILL BUILD IN BEHIND THE LOW
FOR LATER TUESDAY NIGHT AND REMAIN ACROSS THE REGION THROUGH
THURSDAY. THE HIGH WILL SLIDE TO OUR SOUTHEAST THURSDAY NIGHT AND
FRIDAY. A COLD FRONT WILL THEN APPROACH FROM THE WEST FRIDAY AND
CROSS THE REGION FRIDAY NIGHT. THE FRONT MAY BE ACCOMPANIED BY A FEW
SNOW SHOWERS AS IT CROSSES THE REGION FRIDAY NIGHT. HIGH PRESSURE
WILL BUILD BACK IN FOR SATURDAY. TEMPERATURES THROUGH THE PERIOD
WILL BE CLOSE TO NORMAL FOR THIS TIME OF YEAR.
&&
.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
NEAR TERM: IFR CONDITIONS FOR THE SOUTHERN TERMINALS WILL
CONTINUE THROUGH THIS EVENING DUE TO LOW CLOUDS ALONG WITH AREAS
OF MIST AND FOG. THESE CONDITIONS WILL IMPROVE TO VFR LATE TONIGHT
AS LOW PRESSURE DEPARTS AND NW WINDS INCREASE. LOOK FOR CONDITIONS
TO LOWER TO MVFR IN THE NORTH BY EARLY THIS EVENING WITH A PERIOD
OF IFR LIKELY LATE THIS EVENING IN LIGHT SNOW BEFORE CONDITIONS
IMPROVE OVERNIGHT. SUNDAY WILL BE VFR EVERYWHERE BUT WITH STRONG
AND GUSTY NW WINDS.
SHORT TERM: VFR TO BEGIN WITH SUN EVE THEN CONDITIONS TRANSITIONING
TO IFR LATE SUN NGT IN SN CNTRL AND N AND SN CHGNG TO FZRA AND PL
OVR DOWNEAST AREAS. IFR CONDITIONS CONT MON INTO MON EVE WITH MSLY
RN DOWNEAST SITES AND SN CHG TO PL AND FZRA NRN TAF SITES MON
AFTN...XCPT MIDDAY FOR KHUL. IFR CONDITIONS SHOULD IMPROVE TO MVFR
CONDITIONS NW TO SE ACROSS THE TAF SITES LATE MON NGT AND THEN TO
VFR ALL SITES ON TUE.
&&
.MARINE...
NEAR TERM:
WINDS WILL INCREASE LATER THIS EVENING WITH SCA CONDITIONS
EXPECTED OVERNIGHT THROUGH MUCH OF THE DAY SUNDAY BEFORE WINDS
DIMINISH LATE DAY.
SHORT TERM: INITIALLY NO HDLNS FOR SUN NGT...THEN WINDS AND SEAS
INCREASE TO SCA RANGE FOR MON INTO MON NGT AHEAD AND WITH LOW PRES
TRACKING N OF THE WATERS BEFORE SLOWLY SUBSIDING BLO SCA CONDITIONS
ON TUE BEHIND THE LOW.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 1 AM TO 3 PM EST SUNDAY FOR
ANZ050>052.
&&
$$
NEAR TERM...FITZSIMMONS/HEWITT
SHORT TERM...VJN
LONG TERM...DUDA
AVIATION...FITZSIMMONS/HEWITT
MARINE...FITZSIMMONS/HEWITT/VJN
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
342 PM EST SAT DEC 8 2012
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 340 PM EST SAT DEC 8 2012
HIGH PRESSURE IS CURRENTLY LOCATED IN MANITOBA AND ONTARIO...WITH A
RIDGE STRETCHING SOUTHEAST INTO WESTERN UPPER MI AND WI. LIGHT
NORTHWEST FLOW...WITH RUC ANALYZED H850 OF -10 TO -12C...HAS LED TO
LAKE EFFECT CLOUDS AND LIGHT SNOW SHOWERS THROUGH THIS AFTERNOON IN
THE TRADITIONAL NORTHWEST FLOW LOCATIONS.
UPSTREAM...PV ANOMALY IN SRN SD AND NW NEBRASKA WILL SHIFT ENE
TONIGHT AND INTO MN BY 12Z SUNDAY...WITH THE SURFACE LOW FOLLOWING
SUIT. THIS ANOMALY WILL SHIFT NORTHEAST THROUGH WESTERN UPPER
MICHIGAN THROUGH THE DAY ON SUNDAY AND BE WEAKENING DUE TO INFLUENCE
OF SECOND ANOMALY ENTERING NORTHERN MN AND THE SOUTHERN WAVE
BECOMING MORE DOMINATE AS IT DIVES SOUTHEAST THROUGH THE CENTRAL
ROCKIES DURING THE DAY ON SUNDAY. THIS...COMBINED WITH A
STRENGTHENING JET OVER THE OHIO VALLEY ON SUNDAY...WILL ALLOW A
SECONDARY LOW TO DEVELOP IN THE OHIO VALLEY REGION DURING THE DAY
AND PRODUCE A BROAD AREA OF LOW PRESSURE WHICH TRANSITIONS THE LOW
OVER OUR AREA TO A TROUGH. STILL DIFFERENCES IN THE MODELS...BOTH
RUN-TO-RUN AND BETWEEN MODELS...WITH THE POTENTIAL WEAKENING/SPEED
OF THE PV ANOMALY AND THE LOCATION OF THE ASSOCIATED SURFACE TROUGH
HEADING INTO SUNDAY AFTERNOON/EVENING. LATEST TRENDS IN THE MODELS
ARE FOR A SLOWER MOVEMENT OF THE PV ANOMALY THROUGH UPPER MICHIGAN
ON SUNDAY...WHICH KEEPS THE SURFACE TROUGH AXIS OVER
NORTHERN/CENTRAL WISCONSIN.
TONIGHT...THE HIGH PRESSURE RIDGE EXITING TO THE NORTHEAST WILL
PRODUCE QUIET WEATHER BEFORE THE SYSTEM. UPSTREAM DRYING THIS
AFTERNOON HAS ATE AWAY AT SOME OF THE LAKE EFFECT CLOUDS OVER THE
WEST AND ONCE DAYTIME HEATING IS LOST...EXPECT THE SAME TO OCCUR
OVER THE INTERIOR LOCATIONS THIS EVENING. THIS CLEARING WILL MAKE
FOR TRICKY LOW TEMPERATURES TONIGHT AND FOLLOWED THE PREVIOUS SHIFT
BY TRENDED THEM DOWN A LITTLE MORE AS PWATS 65 PERCENT OF NORMAL
AND THERE ARE LIGHT WINDS. WENT WITH LOWS IN UPPER TEENS...BUT BASED
OFF HOW QUICKLY TEMPS FELL THIS MORNING IN CLEARING AREAS...THAT MAY
NOT BE COLD ENOUGH. OTHERWISE...MID/HIGH LEVEL CLOUDS WILL BE ON THE
INCREASE FROM THE SOUTHWEST WITH THE APPROACHING SYSTEM.
SUNDAY...PRECIPITATION BUILDS IN FROM SOUTHWEST TO NORTHEAST THROUGH
THE DAY. STARTING BETWEEN 12-15Z NEAR KIWD...LATE MORNING OR EARLY
AFTERNOON OVER THE CENTRAL...AND MID/LATE AFTERNOON OVER THE EAST.
WITH THE LATEST SLOWER TRENDS...HAVE DELAYED THE START A COUPLE OF
HOURS FROM THE PREVIOUS SHIFT. PLENTY OF COLD AIR ALOFT...SO EXPECT
PRECIPITATION TO BE AS ALL SNOW. AS FOR FORCING...BEST MID LEVEL WAA
IS FOCUSED OVER THE SOUTH CENTRAL AND NEAR LAKE MICHIGAN THROUGH
THE DAY. THIS LINES UP WITH WEAK FGEN BETWEEN H850-650 OVER THE AREA
FOR THE AFTERNOON...BUT SEEMS TO FOCUS OVER THE SOUTHEAST HALF OF
THE CWA LATE IN THE AFTERNOON. IN ADDITION...BROAD 280-290K
ISENTROPIC ASCENT WILL SPREAD OVER THE CWA DURING THE DAY.
FINALLY...H850 TEMPS AROUND -9C SHOULD FAVOR SOME LAKE ENHANCEMENT
FOR THE KEWEENAW AND ALSO FOR LOCATIONS NEAR LAKE MICHIGAN FAVORED
BY ESE WINDS.
WITH THE SLIGHT DELAY WITH THE SLOWER ARRIVAL OF THE PV ANOMALY AND
SURFACE TROUGH BEING A LITTLE FARTHER SOUTH...BEST PRECIPITATION
STRADDLES THE SHORT/LONG TERM TRANSITION. ALL IN ALL...MODEL QPF
FOR SUNDAY INTO SUNDAY NIGHT WITH THE SYNOPTIC FEATURES IS IN THE
0.25-0.4IN FOR MOST AREAS AND WHEN COMBINED WITH A SNOW RATIO AROUND
13-15 TO 1...WOULD PUT 3 TO 6 INCHES OF SYNOPTIC SNOW OVER THE
AREA THROUGH SUNDAY EVENING. OUTSIDE OF ANY LAKE ENHANCEMENT...THE
HIGHEST AMOUNTS SHOULD LINE UP ALONG THE WISCONSIN BORDER WITH THE
SLIGHT SOUTH SHIFT OF THE SURFACE TROUGH. THE LONG TERM DISCUSSION
WILL COVER THE BULK OF THE HEADLINES...BUT DID DROP THE WATCH OVER
THE WESTERN COUNTIES AND HAVE STARTED A LONGER PERIOD ADVISORY FROM
WEST TO EAST THROUGH THE DAY ON SUNDAY.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 340 PM EST SAT DEC 8 2012
MAIN CONCERN IS WITH SNOWFALL FORECAST FOR THE FIRST 24 HOURS OF THE
LONG TERM.
SUN NIGHT/MON...IN GENERAL...MODELS ARE IN GOOD AGREEMENT...BUT
THERE ARE SUBTLE VARIATIONS AT SMALLER SCALES THAT BECOME MAGNIFIED
IN THE SNOWFALL FORECAST. THE DIFFICULTY AND UNCERTAINTY IS DUE TO
THE FACT THAT THE SYSTEM OVER THE REGION SUN NIGHT WILL BE MERGING
WITH A SRN STREAM SYSTEM OVER THE OHIO VALLEY...PLUS THE FACT THAT
MODELS HAVE A HARD TIME CONSISTENTLY HANDLING THE PV ANOMALIES THAT
WILL DRIVE A GOOD PORTS OF THE SNOWFALL WITH THIS SYSTEM. LATEST
RUNS OF THE GFS/NAM/REGIONAL GEM/REGIONAL WRF ARE NOW IN BETTER
AGREEMENT IN BRINGING THE WEAKENING PRIMARY PV ANOMALY FROM NW WI AT
00Z MON TO CENTRAL UPPER MI AROUND 06Z MON...THEN SHEARING IT OUT
AND PUSHING IT NORTHEAST BY 12Z MON. MEANWHILE...THE SECONDARY PV
ANOMALY WILL ROTATE INTO CENTRAL/SRN WI...FARTHER S THAN PREVIOUS
RUNS OF THE MODELS. THE TIMING/LOCATION OF THE PV ANOMALIES IS
CONSISTENT WITH THE OVERALL TREND OVER THE LAST FEW RUNS OF THE
MODELS IN SLOWING THE SYSTEM DOWN AND MOVING IT FARTHER S. THE
RESULTING SFC TROUGH LOOKS TO STAY TO THE S OF THE CWA OVER
CENTRAL/NRN WI. LOW LEVEL FLOW WILL GENERALLY BE ELY AT 00Z MON WITH
850MB TEMPS AROUND -9C. BY 06Z MON...LOW LEVEL WINDS BACK TO MORE
ENE...THEN TO NNE BY 12Z MON AS 850MB TEMPS FALL TO -11C. SYNOPTIC
SNOWFALL AMOUNTS WILL BE HIGHEST OVER THE SRN HALF OF UPPER MI SUN
NIGHT...BUT THAT SHOULD BE OFFSET SOME BY UPSLOPE FLOW IN SOME NRN
LOCATIONS...PARTICULARLY NCENTRAL UPPER MI AND THE KEWEENAW...THEN
OVER THE WRN U.P. LATER SUN NIGHT. 850MB TEMPS FALL ANOTHER COUPLE
OF DEGREES THROUGH THE DAY MON WHILE FLOW BECOMES INCREASING
ANTICYCLONIC AS THE SFC TROUGH MOVES QUICKLY E AND A RIDGE MOVES
OVER WRN LAKE SUPERIOR BY 00Z TUE. THUS...EXPECT LES FROM NNW WINDS
MON MORNING...DIMINISHING THROUGH MON EVENING. WITH THIS TYPE OF
SYSTEM THERE IS INHERENT UNCERTAINTY THAT WILL PROBABLY NOT BE
RESOLVED UNTIL THE SYSTEM IS ON THE DOORSTEP OF THE CWA...SO
CONFIDENCE IN SNOWFALL AMOUNTS IS STILL SOMEWHAT LIMITED. STORM
TOTAL SNOWFALL AMOUNTS OF 3 TO 6 INCHES IS EXPECTED...WITH SOME
LOCALLY HIGHER AMOUNTS POSSIBLE IN THE HIGHER TERRAIN OF WRN
GOGEBIC/ONTONAGON COUNTIES AND NW MARQUETTE/NE BARAGA COUNTIES.
DECIDED IN COORDINATION WITH SHORT TERM SHIFT TO ISSUE WINTER WX
ADVISORIES OVER THE ENTIRE CWA. COULD SEE SOME LOCATIONS GO SLIGHTLY
ABOVE ADVISORY CRITERIA...BUT NOT CONFIDENT ENOUGH IN THAT TO
JUSTIFY WARNING. ALSO...THE TIME THAT THE HEAVIEST SNOW WILL FALL
/SUN EVENING AND EARLY SUN NIGHT/ IS NOT A HIGH IMPACT TIME TRAVEL
WISE...PLUS THE FACT THAT THE STORM TOTAL WILL OCCUR OVER 24 HOURS
OR MORE. ALSO DECIDED ON THE ADVISORY WITH THE IDEA THAT IT WOULD BE
EASIER TO UPGRADE TO A WARNING IF NEEDED THAN HAVE TO CANCEL
WARNINGS AND ISSUE AN ADVISORY IF THE BORDERLINE WARNING AMOUNTS DO
NOT OCCUR...WHICH WOULD LEAD TO A MISSED EVENT FOR
VERIFICATION...SORT OF THE PATH OF LEAST REGRET.
A VERY WEAK SHORTWAVE TROUGH MOVES ACROSS THE AREA TUE INTO TUE
NIGHT...BRINGING SE FLOW OFF LAKE MICHIGAN FROM 12Z TUE INTO WED.
THIS SHOULD LEAD TO LES OFF LAKE MI INTO ERN UPPER MI...ESPECIALLY
SERN SCHOOLCRAFT COUNTY. INVERSION HEIGHTS SHOULD BE AROUND 10KFT
ACCORDING TO THE NAM/GFS WITH UNIDIRECTIONAL WINDS. THE RESULTING
LES BAND SHOULD BE A LARGER MORE DOMINANT ONE...BUT SHOULD ALSO NOT
STAY IN ONE PLACE TOO LONG AS WINDS STEADILY VEER. EVEN SO...MAY END
UP BEING CLOSE TO ADVISORY AMOUNTS. WINDS WILL BECOME WLY ENOUGH
BEHIND THE TROUGH BY 06Z WED TO BRING LES TO NW UPPER MI...BUT WINDS
QUICKLY BECOME ANTICYCLONIC BY 12Z WED AS A SFC RIDGE MOVES TO WRN
LAKE SUPERIOR...SO LIGHTER SNOW AMOUNTS ARE EXPECTED THERE.
A SLIGHTLY STRONGER SYSTEM WILL MOVE N OF THE AREA THU AND DRAW
WARMER TEMPS IN THE CWA...BUT NO SIGNIFICANT PRECIP IS EXPECTED.
HIGHS IN THE MID TO UPPER 30S SEEMS REASONABLE. PRETTY QUIET AFTER
THAT UNTIL MODELS INDICATE A MUCH STRONGER LOW PRESSURE SYSTEM
MOVING NEARBY ON SAT. MODELS ARE IN GOOD AGREEMENT FOR HOW FAR OUT
THE SYSTEM IS...SO WILL USE CONSENSUS OF MODELS FOR THE FORECAST
PAST TUE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1246 PM EST SAT DEC 8 2012
LINGERING LAKE EFFECT CLOUDS WILL AFFECT ALL THREE SITES THIS
AFTERNOON AND LEAD TO MVFR CONDITIONS. BUT AS A SURFACE HIGH
PRESSURE RIDGE MOVES IN...EXPECT DRIER AIR TO ARRIVE AND WINDS TO
TURN OUT OF THE SOUTHEAST THROUGH THE NIGHT. THIS SHOULD PUSH
CONDITIONS BACK TO VFR.
ATTENTION THEN TURNS TO LOW PRESSURE SYSTEM IN THE DAKOTAS THAT
WILL APPROACH THE AREA ON SUNDAY. MODELS ARE STILL STRUGGLING WITH
THE EXACT DETAILS...BUT LATEST RUNS HAVE SLOWED THE SYSTEM SOME AND
HAVE SHOWN A LATER ARRIVAL /TOWARDS AFTERNOON/ FOR SNOW AT
KCMX/KSAW. AT KIWD...SHOULD SEE THE SNOW START AROUND DAYBREAK AND
THEN REALLY INCREASE IN INTENSITY TOWARDS MID MORNING.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 340 PM EST SAT DEC 8 2012
AN AREA OF LOW PRESSURE MOVING OUT OF SOUTHWEST SOUTH DAKOTA WILL
ENTER MN TOMORROW MORNING AND THEN MERGE WITH A LOW DEVELOPING IN
THE GREAT LAKES TO LEAVE A TROUGH OVER NORTHERN WISCONSIN. THIS
TROUGH WILL INCREASE WINDS OUT OF THE EAST AND THEN NORTHEAST
DIRECTION SUNDAY INTO SUNDAY NIGHT. AT THIS TIME...THINKING WINDS
WILL BE IN THE 20-30KT RANGE...ALTHOUGH THERE COULD BE A FEW GALE
FORCE GUSTS TO 35KTS OVER THE WEST AS THE TROUGH SHARPENS LATE
SUNDAY NIGHT. BEHIND THIS FEATURE...A SERIES OF WEAK RIDGES AND
TROUGHS WILL AFFECT LAKE SUPERIOR DURING THE REST OF THE WORK WEEK
AND KEEP WINDS BELOW 25KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY FROM 3 PM SUNDAY TO 7 AM EST MONDAY FOR
MIZ006-007-013-014-085.
WINTER WEATHER ADVISORY FROM 10 AM EST /9 AM CST/ SUNDAY TO 7 AM
EST /6 AM CST/ MONDAY FOR MIZ001-003-004-010-084.
WINTER WEATHER ADVISORY FROM 1 PM SUNDAY TO 1 PM EST MONDAY FOR
MIZ005.
WINTER WEATHER ADVISORY FROM 7 AM EST /6 AM CST/ SUNDAY TO 5 PM
EST /4 PM CST/ MONDAY FOR MIZ002-009.
WINTER WEATHER ADVISORY FROM 9 AM SUNDAY TO 3 AM CST MONDAY FOR
MIZ011-012.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...TITUS
AVIATION...SRF
MARINE...SRF
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
244 PM CST SAT DEC 8 2012
...MUCH COLDER WITH WINDY CONDITIONS LATE TONIGHT AND SUNDAY...
SYNOPSIS... SURFACE LOW PRESSURE RESIDES ACROSS THE CENTRAL HIGH
PLAINS WITH MAIN LOW FORMING NEAR PINE RIDGE SOUTH DAKOTA. LEADING
EDGE OF COLD FRONT JUST PASSED CHADRON. STEEP LAPSE RATES
ATTRIBUTING TO CONVECTIVE SNOW SHOWERS PANHANDLE INTO NORTH
CENTRAL. MUCH OF RADAR ECHOES NOT REACHING GROUND EFFECTIVELY DUE
TO FAIRLY LARGE TEMPERATURES AND DEWPOINT SPREAD. NEVERTHELESS...
THIS HAS BEEN MOISTENING UP THE ATMOSPHERE FOR UPSTREAM
DEVELOPMENT TO TAKE ADVANTAGE OF FOR LATE AFTERNOON INTO THIS
EVENING.
DISCUSSION...
SHORT TERM...TONIGHT THROUGH TUESDAY. MAIN FORECAST CONCERNS OVER
THE NEXT 36 HOURS INVOLVES THE THREAT OF LIGHT SNOW...A RETURN OF
COLD TEMPERATURES...AND THE POTENTIAL OF ADVISORY CRITERIA WIND
SPEEDS.
MODELS CONTINUE TO SHOW GOOD AGREEMENT IN THE NEAR TERM IN WHICH THE
SHORTWAVE TROUGH CURRENTLY LOCATED FROM CENTRAL SOUTH DAKOTA INTO
EASTERN MONTANA AND ASSOCIATED SURFACE LOW DEEPEN AND EJECT EAST
ACROSS THE NORTHERN PLAINS...DRAGGING A STRONG COLD FRONT THROUGH
THE CWA OVERNIGHT TONIGHT. THE RAP MODEL CONTINUES TO INDICATE THE
SURFACE LOW NEAR AND SOUTH OF I90 TONIGHT WHICH REMAINS FARTHER SOUTH
THAN OTHER SHORT TERM MODELS. AN H3 JET MAX ACROSS NORTHERN
COLORADO AND SOUTHERN NEBRASKA THIS EVENING WILL BE FAVORABLE FOR
ASCENT IN THE LEFT EXIT REGION OF JET ACROSS NORTH CENTRAL
NEBRASKA. AS SUGGESTED BY THE RAP MODEL...REGIONAL GEM AND TO A
LESSER EXTEND THE NAM...BANDED SNOWFALL IS FAVORABLE FROM NEAR
MULLEN THROUGH BASSETT. LOCAL SNOWFALL AMOUNTS NEAR AN INCH
POSSIBLE IN THESE BANDED AREAS. OTHERWISE...LIGHT SNOW ALSO
FORECAST TO DEVELOP AND DROP SOUTH INTO FAR NORTHERN NEBRASKA LATE
TONIGHT INTO SUNDAY MORNING. THIS IS WITHIN SOUTHERN PERIPHERY OF
DEFORMATION ZONE TO BE ACROSS EASTERN SOUTH DAKOTA INTO SOUTH
CENTRAL SOUTH DAKOTA. ANY ASSOCIATED SNOWFALL WOULD REMAIN A HALF
INCH OR LESS. ACROSS THE SOUTHERN HALF OF FORECAST AREA...ANY
LINGERING SNOW OR FLURRIES FROM THIS EVENING SHOULD END SOON
AFTER MIDNIGHT.
STRONG COLD AIR ADVECTION AND LOW LEVEL PRESSURE RISES WILL
FOLLOW THE SURFACE BOUNDARY PASSAGE OVERNIGHT TONIGHT. THE
PRESSURE RISES WILL HELP TIGHTEN THE SURFACE GRADIENT AND ALLOW
FOR GUSTY CONDITIONS LATER TONIGHT INTO SUNDAY. THE MODELS HAVE
SHOWN A SLIGHT SOUTHWARD TREND IN THE TRACK OF THE SURFACE
LOW...NOW ACROSS FAR SOUTHWEST MINNESOTA. THIS TRACK FAVORS
SLIGHTLY STRONGER SURFACE WINDS THAN PREVIOUSLY ANTICIPATED. WILL
KEEP WIND SPEEDS JUST BELOW ADVISORY CRITERIA...ESPECIALLY SINCE
THE STRONGEST PRESSURE RISES ARE EXPECTED DURING THE EARLY MORNING
HOURS...DIURNALLY UNFAVORABLE FOR ADVISORY CRITERIA WIND.
BUT...WIDESPREAD SUB ZERO WIND CHILLS WILL OCCUR...WITH THE
POTENTIAL OF SOME OF THE LOWEST READINGS APPROACHING MINUS TEN OR
COLDER THROUGH SUNDAY MORNING ACROSS OUR NORTHERN ZONES. HIGHS ON
SUNDAY WILL BE COLD...WITH READINGS TRENDED DOWN TO NEAR 15 AT
VALENTINE TO THE MID 20S FAR SOUTH. WE WILL NEED TO WATCH LOW
TEMPERATURES FOR MONDAY MORNING...AS ANY SNOWFALL WOULD ALLOW
READINGS TO PLUMMET...TO POSSIBLY BELOW ZERO. CURRENT FORECAST HAS
LOWS 1 TO 5 ABOVE MOST AREAS...AS WIDESPREAD ACCUMULATING SNOW IS
NOT ANTICIPATED. TEMPERATURES BEGIN TO MODERATE SLOWLY MONDAY
AFTERNOON AS WEAK WAA INFILTRATES FROM THE WEST IN ADVANCE OF THE
NEXT SHORTWAVE TROUGH. HIGHS TO RANGE IN THE 30S. THEN A WESTERLY
DOWNSLOPE TUESDAY TO WARM READINGS TO THE MID 30S TO LOWER 40S.
LONG TERM...TUESDAY NIGHT THROUGH SATURDAY. SHORTWAVE RIDGING AND
WAA TAKE HOLD WEDNESDAY THROUGH THURSDAY...WITH TEMPERATURES SLIGHTLY
ABOVE SEASONAL NORMS WEDNESDAY AND NEAR NORMAL THURSDAY. WILL NEED
TO MONITOR IF A BACK DOOR COLD FRONT DROPS INTO NORTH CENTRAL
NEBRASKA THURSDAY. THE ECMWF AND GEM KEEP COLDER AIR TO THE NORTH
INTO SOUTH DAKOTA...WHILE THE GFS BRINGS IT SOUTH INTO NORTHERN
NEBRASKA. THE NEXT SIGNIFICANT TROUGH IS SHOWN TO REACH THE FOUR
CORNERS REGION 12Z FRIDAY AND TRACK INTO NORTHWEST MISSOURI AS A
NEGATIVELY TILTED CLOSED LOW BY 12Z SATURDAY PER THE ECMWF
SOLUTION. THE GFS ALSO INDICATES A NEGATIVELY TILTED
TROUGH...ALTHOUGH AS AN OPEN WAVE FROM WESTERN SOUTH DAKOTA INTO
NORTHERN NEBRASKA. PRECIPITATION CHANCES NOW BROUGHT INTO EASTERN
NEBRASKA FRIDAY NIGHT INCLUDING FAR EASTERN PORTIONS OF NORTH
CENTRAL NEBRASKA. HIGHS FRIDAY FORECAST TO RANGE IN THE 30S AND
MID 30S TO LOW 40S SATURDAY.
&&
.AVIATION...
A SURFACE LOW OVER SOUTHWEST SOUTH DAKOTA WILL PROGRESS EAST ACROSS
SOUTHERN SOUTH DAKOTA THROUGH THE EVENING...WHICH WILL BRING LOWER
CEILINGS AND CHANCES FOR SNOW TO PORTIONS OF NORTHERN
NEBRASKA...INCLUDING KVTN. THERE WILL BE A CHANCE FOR LIGHT SNOW
THIS AFTERNOON IN THESE AREAS...BUT EXPECT VISIBILITIES TO STAY
ABOVE 5SM UNTIL LATER THIS AFTERNOON THROUGH EARLY EVENING WHEN THE
SNOW COULD INTENSIFY AND BRING VISIBILITIES AND CEILINGS DOWN TO
MVFR AND POSSIBLY IFR FOR A TIME. THE EXPECTED PRECIPITATION TYPE
WILL MAINLY BE SNOW...AND THE PRIMARY AREA THAT COULD SEE
ACCUMULATING SNOW IS LIKELY TO STAY NORTH OF A KAIA TO KTIF TO KBVN
LINE.
IN ADDITION...AS THE SURFACE LOW MOVES EAST...A COLD FRONT WILL
MOVE THROUGH THE STATE SWITCHING WINDS TO THE NORTHWEST. COULD SEE
GUSTY WINDS BETWEEN 30 AND 40 KTS...ESPECIALLY ACROSS THE NORTHERN
PARTS OF NEBRASKA LATE TONIGHT INTO SUNDAY MORNING.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...ROBERG
AVIATION...BROOKS
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
106 PM CST SAT DEC 8 2012
.UPDATE...
ONE MORE UPDATE TO INCREASE PRECIPITATION CHANCES ACROSS NORTHERN
NEBRASKA THIS AFTERNOON. RADAR ECHOES HAVE BEEN PERSISTENT THROUGH
THE MORNING HOURS ACROSS NORTHERN NEBRASKA WHICH HAS MOISTENED THE
COLUMN...WHICH HAS BEEN CONFIRMED BY LAPS SOUNDINGS IN THE AREA.
ALSO...HAVE HAD CONFIRMATION OF SNOW PELLETS FROM AN OBSERVER NEAR
KAIA WITH AREA WEBCAMS SHOWING SOME LIGHT SNOW ON GRASSY SURFACES
IN PARTS OF SHERIDAN COUNTY. LATEST SURFACE ANALYSIS SHOWS THE
SURFACE LOW HAS MIGRATED INTO SOUTHWEST SOUTH DAKOTA. THE RUC IS
SHOWING GOOD MOISTURE CONTINUING TO ADVECT EASTWARD ON THE SOUTH
SIDE OF THE LOW AS IT MOVES STRAIGHT EAST JUST NORTH OF THE SD/NE
BORDER THIS AFTERNOON. THIS...COMBINED WITH DECENT ISENTROPIC LIFT
IN THE LAYER AND WITH RADAR ECHOES EXTENDING INTO CENTRAL WYOMING
HAD THE CONFIDENCE TO INCREASE PRECIPITATION CHANCES THROUGH THE
AFTERNOON. DEWPOINT SPREADS SHOULD KEEP MOST OF THE PRECIPITATION
AS SNOW...ALTHOUGH SOME RAIN COULD MIX IN AREAS SOUTH OF THE
HIGHWAY 2/91 CORRIDOR.
&&
.PREV DISCUSSION... /ISSUED 1156 AM CST SAT DEC 8 2012/
AVIATION...
A SURFACE LOW WILL PASS ACROSS SOUTHERN SOUTH DAKOTA THROUGH
TONIGHT...WHICH WILL BRING LOWER CEILINGS AND CHANCES FOR SNOW TO
PORTIONS OF NORTHERN NEBRASKA...INCLUDING KVTN. THERE WILL
CONTINUE TO BE A CHANCE FOR LIGHT SNOW THIS AFTERNOON IN THESE
AREAS...BUT EXPECT VISIBILITIES TO STAY ABOVE 5SM UNTIL LATER THIS
AFTERNOON THROUGH EARLY EVENING WHEN THE SNOW COULD INTENSIFY AND
BRING VISIBILITIES AND CEILINGS DOWN TO MVFR AND POSSIBLY IFR FOR A
TIME. THE PRIMARY PRECIPITATION AREA IS LIKELY TO STAY NORTH OF A
KAIA TO KTIF TO KBVN LINE WITH THE EXPECTED PRECIPITATION TYPE
BEING SNOW EVEN IF SURFACE TEMPERATURES RISE ABOVE FREEZING.
IN ADDITION...AS THE SURFACE LOW MOVES EAST...A COLD FRONT WILL
MOVE THROUGH THE STATE SWITCHING WINDS TO THE NORTHWEST. COULD SEE
GUSTY WINDS BETWEEN 30 AND 40 KTS...ESPECIALLY ACROSS THE NORTHERN
PARTS OF NEBRASKA LATE TONIGHT INTO SUNDAY MORNING.
PREV DISCUSSION... /ISSUED 1021 AM CST SAT DEC 8 2012/
UPDATE...
MADE AN ADJUSTMENT TO THE FORECAST FOR TODAY TO ADD IN CHANCE FOR
FLURRIES ACROSS NORTHERN NEBRASKA THIS MORNING AS RADAR ECHOES
HAVE EXPANDED THROUGH THE AREA. THERE REMAINS QUITE A BIT OF DRY
AIR IN THE LOW LEVELS THOUGH WITH CEILINGS STILL AT OR ABOVE 5K
FEET EVEN AS THE COLUMN SATURATES FROM TO DOWN. THEREFORE DON/T
EXPECT ANY ACCUMULATING PRECIPITATION YET THIS MORNING. WATER
VAPOR IMAGERY SHOWS THE MID/UPPER LEVEL PV ANOMALY PUSHING INTO
CENTRAL WYOMING WHICH WILL CONTINUE TO MOVE EAST INTO WESTERN
NEBRASKA THIS AFTERNOON. STILL THINK IT LOOKS GOOD FOR THIS TO
CAUSE THE SURFACE LOW /CURRENTLY OVER THE MONTANA/WYOMING/SOUTH
DAKOTA TRIPLE POINT/ TO STRENGTHEN THIS AFTERNOON AS IT MOVES
EAST. NEAR-TERM AND MESOSCALE MODELS DO INDICATE GOOD WARMING
JUST AHEAD OF THE COLD FRONT THIS AFTERNOON. THINK CLOUD COVER MAY
LIMIT THIS WARMING THOUGH...ESPECIALLY OVER NORTHERN NEBRASKA
WHERE CLOUDS SHOULD BE MORE ABUNDANT. SO DID ADJUST HIGHS DOWNWARD
SLIGHTLY IN THESE AREAS.
WILL CONTINUE TO MONITOR RADAR TRENDS INTO THE AFTERNOON AS THE
UPPER LEVEL SHORTWAVE MOVES CLOSER AND MAY NEED TO ADJUST
PRECIPITATION CHANCES UPWARD FOR THE AFTERNOON HOURS ACROSS THE
NORTH.
PREV DISCUSSION... /ISSUED 624 AM CST SAT DEC 8 2012/
UPDATE...
DISCUSSION...
A NEW FORECAST IS IN PLACE...MAINLY AFFECTING NORTHERN NEBRASKA.
THE RAP MODEL...WHICH HAS BEEN PERFORMING WELL WITH THIS
SYSTEM...SUGGESTS THE SFC LOW WILL TRACK ALONG THE SD-NEB BORDER
LATE THIS AFTN AND THIS EVENING. THIS IS ABOUT 100 MILES OR SO
FARTHER SOUTH THAN THE ENSEMBLE FCST.
IT ALSO CARRIES THE PV15 CENTER FARTHER SOUTH. ENHANCED
ADVECTIONS OF TEMPERATURE AND MOISTURE SHOW A MARKED STRENGTHENING
OF 700 MB FRONTOGENESIS NEAR THE SFC LOW LATE THIS AFTN AND THIS
EVENING. THUS...AS INDICATED BY THE MODEL...GREATER POPS AND QPF
ARE WARRANTED FOR NRN NEB WITH A RAIN CHANGEOVER TO SNOW WITH THE
PASSAGE OF A PACIFIC FRONT EARLY THIS EVENING FOLLOWED BY ARCTIC
AIR MOVING IN AROUND 06Z OR LATER.
POPS ARE HELD AT 40 PERCENT GIVEN THE UNCERTAINTIES OF THIS
RAPID CHANGE IN THE MODEL AND THE MIXED PCPN WOULD PERHAPS YEILD
AN INCH OR TWO OF SNOW. THE REST OF THE FCST IS ON TRACK.
PREV DISCUSSION... /ISSUED 400 AM CST SAT DEC 8 2012/
SYNOPSIS...
EVENING HAND ANALYSIS OF THE H5 LEVEL REVEALS A BROAD LONGWAVE
TROUGH ENCOMPASSING MUCH OF THE CONTIGUOUS 48...WITH RIDGING OFF
BOTH THE WESTERN AND EASTERN COASTS. SEVERAL SHORTWAVES ARE SEEN
MOVING THROUGH THE BROAD TROUGH...WITH ONE NOW EAST OF THE UPPER
MISSISSIPPI VALLEY...AND THE NEXT APPROACHING THE NORTHERN/CENTRAL
HIGH PLAINS FROM THE WEST. AT THE SURFACE...AN AREA OF LOW PRESSURE
IS STARTING TO DEEPEN OVER CENTRAL MONTANA WITH HIGH PRESSURE
LOCATED OVER THE MISSOURI VALLEY. WHILE WINDS ARE FAIRLY LIGHT AND
VARIABLE AT THIS HOUR ACROSS THE CWA...FURTHER WEST ACROSS THE HIGH
PLAINS...SURFACE WINDS ARE STARTING TO TAKE ON A MORE SOUTHERLY
COMPONENT. TEMPERATURES EARLY THIS AM RANGE FROM A CHILLY 13
DEGREES FAHRENHEIT AT KLBF...TO AS WARM AS 30 AT KONL WHERE STRATUS
IS LOCKED IN PLACE.
DISCUSSION...
SHORT TERM...TONIGHT THROUGH 12Z TUESDAY. MAIN FORECAST CONCERNS
OVER THE NEXT 72 HOURS INVOLVES THE THREAT OF LIGHT SNOW...A RETURN
OF COLD TEMPERATURES...AND THE POTENTIAL OF ADVISORY CRITERIA WIND
SPEEDS.
MODELS CONTINUE TO SHOW GOOD AGREEMENT IN THE NEAR TERM IN WHICH THE
WESTERN SHORTWAVE TROUGH AND ASSOCIATED SURFACE LOW DEEPEN AND EJECT
EAST ACROSS THE NORTHERN PLAINS...DRAGGING A STRONG COLD FRONT
THROUGH THE CWA LATE TODAY/OVERNIGHT TONIGHT. THE STRONGEST OMEGA
CONTINUES TO BE SUGGESTED WELL NORTH OF THE CWA...IN CLOSE VICINITY
TO THE TROUGH AXIS...HOWEVER MOST NEAR TERM MODEL SOLUTIONS GENERATE
LIGHT QPF AHEAD OF A MID-LEVEL FGEN BAND WHERE WEAK THERMAL
ADVECTION AND A BRIEF PERIOD OF UPGLIDE MAY BE SUFFICIENT ENOUGH TO
SQUEEZE OUT A HUNDREDTH OR TWO OF AN INCH OF PRECIPITATION THIS
AFTERNOON. THE BETTER DYNAMICS FOR PRECIPITATION PRODUCTION ARRIVES
WITH THE MID LEVEL FRONTOGENETIC BAND LATE THIS
AFTERNOON/EVENING...HOWEVER FORECAST PROXIMITY SOUNDINGS FROM ACROSS
THE CWA SUGGEST THE LOWER LEVELS OF THE ATMOSPHERE WILL QUICKLY DRY
OUT AS STRONG COLD/DRY AIR ADVECTION SPILLS IN BEHIND THE PASSING
BOUNDARY. THE ENSEMBLES...AND DETERMINISTIC SOLUTIONS ALL HAVE
CONVERGED THAT AT MOST LESS THAN .05 OF AN INCH OF QPF WOULD BE
GENERATED...SO ONLY LOOKING FOR A DUSTING TO POSSIBLY A HALF OF AN
INCH ACROSS THE SANDHILLS AND POINTS SOUTHEAST WHERE ADDITIONAL LIFT
MAY BE GENERATED WITHIN THE VICINITY OF THE RIGHT ENTRANCE OF A
PASSING UPPER JET. ACROSS NORTHERN NEBRASKA...THE NEAR TERM
CONSENSUS IS SUGGESTING A PERIOD OF POSSIBLE WRAP AROUND AS THE
SURFACE LOW ADVANCES INTO WEST CENTRAL MINNESOTA...THE POTENTIAL OF
SLIGHTLY HEAVIER SNOW ACCUMULATION EXIST...BUT LESS THAN AN INCH
WOULD BE EXPECT AT BEST WITH THE SNOW FALLING OVERNIGHT TONIGHT.
THE SHORTWAVE QUICKLY ADVANCES EAST OVERNIGHT BRINGING AN END TO
PRECIPITATION CHANCES FOR THE FORESEEABLE FUTURE AS AN OVERALL LACK
OF KINEMATIC FORCING IS SUGGESTED IN THE SHORT AND LONG TERM
SOLUTIONS.
STRONG COLD AIR ADVECTION AND MODEST LOW LEVEL PRESSURE RISES WILL
FOLLOW THE SURFACE BOUNDARY PASSAGE OVERNIGHT TONIGHT. THE
PRESSURE RISES WILL HELP TIGHTEN THE SURFACE GRADIENT AND ALLOW FOR
GUSTY CONDITIONS EARLY ON SUNDAY. THE MODELS HAVE SHOWN A SLIGHT
NORTHWARD TREND IN THE TRACK OF THE SURFACE LOW...NOW ACROSS WEST
CENTRAL MINNESOTA. THIS TRACK FAVORS SLIGHTLY WEAKER SURFACE WINDS
THAN PREVIOUSLY ANTICIPATED. SO WILL KEEP WIND SPEEDS BELOW
ADVISORY CRITERIA...ESPECIALLY SINCE THE STRONGEST PRESSURE RISES
ARE EXPECTED DURING THE EARLY MORNING HOURS...DIURNALLY UNFAVORABLE
FOR ADVISORY CRITERIA WIND. BUT...WIDESPREAD SUB ZERO WIND CHILLS
WILL BE POSSIBLE...WITH THE POTENTIAL OF SOME OF THE LOWEST READINGS
APPROACHING MINUS TEN OR COLDER AS H9 TEMPERATURES FALL AS COLD AS
MINUS 12C ACROSS OUR NORTHERN ZONES. HIGHS ON SUNDAY WILL BE
CHILLY...WITH READINGS RANGING FROM THE UPPER TEENS ACROSS THE
NORTH...TO THE UPPER 20S ACROSS THE FAR SOUTHWEST. WE WILL NEED TO
WATCH LOW TEMPERATURES FOR MONDAY MORNING...AS ANY SNOWFALL WOULD
ALLOW READINGS TO PLUMMET...TO POSSIBLY BELOW 0F. WILL KEEP
FORECAST VALUES IN THE SINGLE DIGITS FOR NOW...AS WIDESPREAD
ACCUMULATING SNOW IS NOT ANTICIPATED. TEMPERATURES BEGIN TO MODERATE
SLOWLY MONDAY AFTERNOON AS WEAK WAA INFILTRATES FROM THE WEST IN
ADVANCE OF THE NEXT SHORTWAVE TROUGH.
LONG TERM...12Z TUESDAY AND BEYOND. THE NEXT WAVE PASSES THROUGH
EARLY TUESDAY...HOWEVER MOISTURE REMAINS IN QUESTION...AND KINEMATIC
FORCING REMAINS SOMEWHAT WEAK AND TO THE SOUTH...THUS CONFIDENCE IS
TOO LOW TO INTRODUCE POPS INTO THE FORECAST. OTHERWISE SHORTWAVE
RIDGING AND WAA TAKE HOLD THROUGH THE END OF NEXT WEEK...WITH
TEMPERATURES REMAINING NEAR TO SLIGHTLY ABOVE SEASONAL NORMS. THE
NEXT SIGNIFICANT TROUGH IS SHOWN TO ARRIVE ACROSS THE WEST LATE NEXT
WEEK...BUT WITH THIS EVENINGS MODEL RUNS...PRECIPITATION CHANCES
LOOK TO REMAIN WELL TO THE SOUTH AND WEST OF THE CWA.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...JACOBS
AVIATION/UPDATE...BROOKS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1156 AM CST SAT DEC 8 2012
.AVIATION...
A SURFACE LOW WILL PASS ACROSS SOUTHERN SOUTH DAKOTA THROUGH
TONIGHT...WHICH WILL BRING LOWER CEILINGS AND CHANCES FOR SNOW TO
PORTIONS OF NORTHERN NEBRASKA...INCLUDING KVTN. THERE WILL
CONTINUE TO BE A CHANCE FOR LIGHT SNOW THIS AFTERNOON IN THESE
AREAS...BUT EXPECT VISIBILITIES TO STAY ABOVE 5SM UNTIL LATER THIS
AFTERNOON THROUGH EARLY EVENING WHEN THE SNOW COULD INTENSIFY AND
BRING VISIBILITIES AND CEILINGS DOWN TO MVFR AND POSSIBLY IFR FOR A
TIME. THE PRIMARY PRECIPITATION AREA IS LIKELY TO STAY NORTH OF A
KAIA TO KTIF TO KBVN LINE WITH THE EXPECTED PRECIPITATION TYPE
BEING SNOW EVEN IF SURFACE TEMPERATURES RISE ABOVE FREEZING.
IN ADDITION...AS THE SURFACE LOW MOVES EAST...A COLD FRONT WILL
MOVE THROUGH THE STATE SWITCHING WINDS TO THE NORTHWEST. COULD SEE
GUSTY WINDS BETWEEN 30 AND 40 KTS...ESPECIALLY ACROSS THE NORTHERN
PARTS OF NEBRASKA LATE TONIGHT INTO SUNDAY MORNING.
&&
.PREV DISCUSSION... /ISSUED 1021 AM CST SAT DEC 8 2012/
UPDATE...
MADE AN ADJUSTMENT TO THE FORECAST FOR TODAY TO ADD IN CHANCE FOR
FLURRIES ACROSS NORTHERN NEBRASKA THIS MORNING AS RADAR ECHOES
HAVE EXPANDED THROUGH THE AREA. THERE REMAINS QUITE A BIT OF DRY
AIR IN THE LOW LEVELS THOUGH WITH CEILINGS STILL AT OR ABOVE 5K
FEET EVEN AS THE COLUMN SATURATES FROM TO DOWN. THEREFORE DON/T
EXPECT ANY ACCUMULATING PRECIPITATION YET THIS MORNING. WATER
VAPOR IMAGERY SHOWS THE MID/UPPER LEVEL PV ANOMALY PUSHING INTO
CENTRAL WYOMING WHICH WILL CONTINUE TO MOVE EAST INTO WESTERN
NEBRASKA THIS AFTERNOON. STILL THINK IT LOOKS GOOD FOR THIS TO
CAUSE THE SURFACE LOW /CURRENTLY OVER THE MONTANA/WYOMING/SOUTH
DAKOTA TRIPLE POINT/ TO STRENGTHEN THIS AFTERNOON AS IT MOVES
EAST. NEAR-TERM AND MESOSCALE MODELS DO INDICATE GOOD WARMING
JUST AHEAD OF THE COLD FRONT THIS AFTERNOON. THINK CLOUD COVER MAY
LIMIT THIS WARMING THOUGH...ESPECIALLY OVER NORTHERN NEBRASKA
WHERE CLOUDS SHOULD BE MORE ABUNDANT. SO DID ADJUST HIGHS DOWNWARD
SLIGHTLY IN THESE AREAS.
WILL CONTINUE TO MONITOR RADAR TRENDS INTO THE AFTERNOON AS THE
UPPER LEVEL SHORTWAVE MOVES CLOSER AND MAY NEED TO ADJUST
PRECIPITATION CHANCES UPWARD FOR THE AFTERNOON HOURS ACROSS THE
NORTH.
PREV DISCUSSION... /ISSUED 624 AM CST SAT DEC 8 2012/
UPDATE...
DISCUSSION...
A NEW FORECAST IS IN PLACE...MAINLY AFFECTING NORTHERN NEBRASKA.
THE RAP MODEL...WHICH HAS BEEN PERFORMING WELL WITH THIS
SYSTEM...SUGGESTS THE SFC LOW WILL TRACK ALONG THE SD-NEB BORDER
LATE THIS AFTN AND THIS EVENING. THIS IS ABOUT 100 MILES OR SO
FARTHER SOUTH THAN THE ENSEMBLE FCST.
IT ALSO CARRIES THE PV15 CENTER FARTHER SOUTH. ENHANCED
ADVECTIONS OF TEMPERATURE AND MOISTURE SHOW A MARKED STRENGTHENING
OF 700 MB FRONTOGENESIS NEAR THE SFC LOW LATE THIS AFTN AND THIS
EVENING. THUS...AS INDICATED BY THE MODEL...GREATER POPS AND QPF
ARE WARRANTED FOR NRN NEB WITH A RAIN CHANGEOVER TO SNOW WITH THE
PASSAGE OF A PACIFIC FRONT EARLY THIS EVENING FOLLOWED BY ARCTIC
AIR MOVING IN AROUND 06Z OR LATER.
POPS ARE HELD AT 40 PERCENT GIVEN THE UNCERTAINTIES OF THIS
RAPID CHANGE IN THE MODEL AND THE MIXED PCPN WOULD PERHAPS YEILD
AN INCH OR TWO OF SNOW. THE REST OF THE FCST IS ON TRACK.
PREV DISCUSSION... /ISSUED 400 AM CST SAT DEC 8 2012/
SYNOPSIS...
EVENING HAND ANALYSIS OF THE H5 LEVEL REVEALS A BROAD LONGWAVE
TROUGH ENCOMPASSING MUCH OF THE CONTIGUOUS 48...WITH RIDGING OFF
BOTH THE WESTERN AND EASTERN COASTS. SEVERAL SHORTWAVES ARE SEEN
MOVING THROUGH THE BROAD TROUGH...WITH ONE NOW EAST OF THE UPPER
MISSISSIPPI VALLEY...AND THE NEXT APPROACHING THE NORTHERN/CENTRAL
HIGH PLAINS FROM THE WEST. AT THE SURFACE...AN AREA OF LOW PRESSURE
IS STARTING TO DEEPEN OVER CENTRAL MONTANA WITH HIGH PRESSURE
LOCATED OVER THE MISSOURI VALLEY. WHILE WINDS ARE FAIRLY LIGHT AND
VARIABLE AT THIS HOUR ACROSS THE CWA...FURTHER WEST ACROSS THE HIGH
PLAINS...SURFACE WINDS ARE STARTING TO TAKE ON A MORE SOUTHERLY
COMPONENT. TEMPERATURES EARLY THIS AM RANGE FROM A CHILLY 13
DEGREES FAHRENHEIT AT KLBF...TO AS WARM AS 30 AT KONL WHERE STRATUS
IS LOCKED IN PLACE.
DISCUSSION...
SHORT TERM...TONIGHT THROUGH 12Z TUESDAY. MAIN FORECAST CONCERNS
OVER THE NEXT 72 HOURS INVOLVES THE THREAT OF LIGHT SNOW...A RETURN
OF COLD TEMPERATURES...AND THE POTENTIAL OF ADVISORY CRITERIA WIND
SPEEDS.
MODELS CONTINUE TO SHOW GOOD AGREEMENT IN THE NEAR TERM IN WHICH THE
WESTERN SHORTWAVE TROUGH AND ASSOCIATED SURFACE LOW DEEPEN AND EJECT
EAST ACROSS THE NORTHERN PLAINS...DRAGGING A STRONG COLD FRONT
THROUGH THE CWA LATE TODAY/OVERNIGHT TONIGHT. THE STRONGEST OMEGA
CONTINUES TO BE SUGGESTED WELL NORTH OF THE CWA...IN CLOSE VICINITY
TO THE TROUGH AXIS...HOWEVER MOST NEAR TERM MODEL SOLUTIONS GENERATE
LIGHT QPF AHEAD OF A MID-LEVEL FGEN BAND WHERE WEAK THERMAL
ADVECTION AND A BRIEF PERIOD OF UPGLIDE MAY BE SUFFICIENT ENOUGH TO
SQUEEZE OUT A HUNDREDTH OR TWO OF AN INCH OF PRECIPITATION THIS
AFTERNOON. THE BETTER DYNAMICS FOR PRECIPITATION PRODUCTION ARRIVES
WITH THE MID LEVEL FRONTOGENETIC BAND LATE THIS
AFTERNOON/EVENING...HOWEVER FORECAST PROXIMITY SOUNDINGS FROM ACROSS
THE CWA SUGGEST THE LOWER LEVELS OF THE ATMOSPHERE WILL QUICKLY DRY
OUT AS STRONG COLD/DRY AIR ADVECTION SPILLS IN BEHIND THE PASSING
BOUNDARY. THE ENSEMBLES...AND DETERMINISTIC SOLUTIONS ALL HAVE
CONVERGED THAT AT MOST LESS THAN .05 OF AN INCH OF QPF WOULD BE
GENERATED...SO ONLY LOOKING FOR A DUSTING TO POSSIBLY A HALF OF AN
INCH ACROSS THE SANDHILLS AND POINTS SOUTHEAST WHERE ADDITIONAL LIFT
MAY BE GENERATED WITHIN THE VICINITY OF THE RIGHT ENTRANCE OF A
PASSING UPPER JET. ACROSS NORTHERN NEBRASKA...THE NEAR TERM
CONSENSUS IS SUGGESTING A PERIOD OF POSSIBLE WRAP AROUND AS THE
SURFACE LOW ADVANCES INTO WEST CENTRAL MINNESOTA...THE POTENTIAL OF
SLIGHTLY HEAVIER SNOW ACCUMULATION EXIST...BUT LESS THAN AN INCH
WOULD BE EXPECT AT BEST WITH THE SNOW FALLING OVERNIGHT TONIGHT.
THE SHORTWAVE QUICKLY ADVANCES EAST OVERNIGHT BRINGING AN END TO
PRECIPITATION CHANCES FOR THE FORESEEABLE FUTURE AS AN OVERALL LACK
OF KINEMATIC FORCING IS SUGGESTED IN THE SHORT AND LONG TERM
SOLUTIONS.
STRONG COLD AIR ADVECTION AND MODEST LOW LEVEL PRESSURE RISES WILL
FOLLOW THE SURFACE BOUNDARY PASSAGE OVERNIGHT TONIGHT. THE
PRESSURE RISES WILL HELP TIGHTEN THE SURFACE GRADIENT AND ALLOW FOR
GUSTY CONDITIONS EARLY ON SUNDAY. THE MODELS HAVE SHOWN A SLIGHT
NORTHWARD TREND IN THE TRACK OF THE SURFACE LOW...NOW ACROSS WEST
CENTRAL MINNESOTA. THIS TRACK FAVORS SLIGHTLY WEAKER SURFACE WINDS
THAN PREVIOUSLY ANTICIPATED. SO WILL KEEP WIND SPEEDS BELOW
ADVISORY CRITERIA...ESPECIALLY SINCE THE STRONGEST PRESSURE RISES
ARE EXPECTED DURING THE EARLY MORNING HOURS...DIURNALLY UNFAVORABLE
FOR ADVISORY CRITERIA WIND. BUT...WIDESPREAD SUB ZERO WIND CHILLS
WILL BE POSSIBLE...WITH THE POTENTIAL OF SOME OF THE LOWEST READINGS
APPROACHING MINUS TEN OR COLDER AS H9 TEMPERATURES FALL AS COLD AS
MINUS 12C ACROSS OUR NORTHERN ZONES. HIGHS ON SUNDAY WILL BE
CHILLY...WITH READINGS RANGING FROM THE UPPER TEENS ACROSS THE
NORTH...TO THE UPPER 20S ACROSS THE FAR SOUTHWEST. WE WILL NEED TO
WATCH LOW TEMPERATURES FOR MONDAY MORNING...AS ANY SNOWFALL WOULD
ALLOW READINGS TO PLUMMET...TO POSSIBLY BELOW 0F. WILL KEEP
FORECAST VALUES IN THE SINGLE DIGITS FOR NOW...AS WIDESPREAD
ACCUMULATING SNOW IS NOT ANTICIPATED. TEMPERATURES BEGIN TO MODERATE
SLOWLY MONDAY AFTERNOON AS WEAK WAA INFILTRATES FROM THE WEST IN
ADVANCE OF THE NEXT SHORTWAVE TROUGH.
LONG TERM...12Z TUESDAY AND BEYOND. THE NEXT WAVE PASSES THROUGH
EARLY TUESDAY...HOWEVER MOISTURE REMAINS IN QUESTION...AND KINEMATIC
FORCING REMAINS SOMEWHAT WEAK AND TO THE SOUTH...THUS CONFIDENCE IS
TOO LOW TO INTRODUCE POPS INTO THE FORECAST. OTHERWISE SHORTWAVE
RIDGING AND WAA TAKE HOLD THROUGH THE END OF NEXT WEEK...WITH
TEMPERATURES REMAINING NEAR TO SLIGHTLY ABOVE SEASONAL NORMS. THE
NEXT SIGNIFICANT TROUGH IS SHOWN TO ARRIVE ACROSS THE WEST LATE NEXT
WEEK...BUT WITH THIS EVENINGS MODEL RUNS...PRECIPITATION CHANCES
LOOK TO REMAIN WELL TO THE SOUTH AND WEST OF THE CWA.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...JACOBS
UPDATES...CDC/BROOKS
AVIATION...BROOKS
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1021 AM CST SAT DEC 8 2012
.UPDATE...
MADE AN ADJUSTMENT TO THE FORECAST FOR TODAY TO ADD IN CHANCE FOR
FLURRIES ACROSS NORTHERN NEBRASKA THIS MORNING AS RADAR ECHOES
HAVE EXPANDED THROUGH THE AREA. THERE REMAINS QUITE A BIT OF DRY
AIR IN THE LOW LEVELS THOUGH WITH CEILINGS STILL AT OR ABOVE 5K
FEET EVEN AS THE COLUMN SATURATES FROM TO DOWN. THEREFORE DON/T
EXPECT ANY ACCUMULATING PRECIPITATION YET THIS MORNING. WATER
VAPOR IMAGERY SHOWS THE MID/UPPER LEVEL PV ANOMALY PUSHING INTO
CENTRAL WYOMING WHICH WILL CONTINUE TO MOVE EAST INTO WESTERN
NEBRASKA THIS AFTERNOON. STILL THINK IT LOOKS GOOD FOR THIS TO
CAUSE THE SURFACE LOW /CURRENTLY OVER THE MONTANA/WYOMING/SOUTH
DAKOTA TRIPLE POINT/ TO STRENGTHEN THIS AFTERNOON AS IT MOVES
EAST. NEAR-TERM AND MESOSCALE MODELS DO INDICATE GOOD WARMING
JUST AHEAD OF THE COLD FRONT THIS AFTERNOON. THINK CLOUD COVER MAY
LIMIT THIS WARMING THOUGH...ESPECIALLY OVER NORTHERN NEBRASKA
WHERE CLOUDS SHOULD BE MORE ABUNDANT. SO DID ADJUST HIGHS DOWNWARD
SLIGHTLY IN THESE AREAS.
WILL CONTINUE TO MONITOR RADAR TRENDS INTO THE AFTERNOON AS THE
UPPER LEVEL SHORTWAVE MOVES CLOSER AND MAY NEED TO ADJUST
PRECIPITATION CHANCES UPWARD FOR THE AFTERNOON HOURS ACROSS THE
NORTH.
&&
.PREV DISCUSSION... /ISSUED 624 AM CST SAT DEC 8 2012/
UPDATE...
DISCUSSION...
A NEW FORECAST IS IN PLACE...MAINLY AFFECTING NORTHERN NEBRASKA.
THE RAP MODEL...WHICH HAS BEEN PERFORMING WELL WITH THIS
SYSTEM...SUGGESTS THE SFC LOW WILL TRACK ALONG THE SD-NEB BORDER
LATE THIS AFTN AND THIS EVENING. THIS IS ABOUT 100 MILES OR SO
FARTHER SOUTH THAN THE ENSEMBLE FCST.
IT ALSO CARRIES THE PV15 CENTER FARTHER SOUTH. ENHANCED
ADVECTIONS OF TEMPERATURE AND MOISTURE SHOW A MARKED STRENGTHENING
OF 700 MB FRONTOGENESIS NEAR THE SFC LOW LATE THIS AFTN AND THIS
EVENING. THUS...AS INDICATED BY THE MODEL...GREATER POPS AND QPF
ARE WARRANTED FOR NRN NEB WITH A RAIN CHANGEOVER TO SNOW WITH THE
PASSAGE OF A PACIFIC FRONT EARLY THIS EVENING FOLLOWED BY ARCTIC
AIR MOVING IN AROUND 06Z OR LATER.
POPS ARE HELD AT 40 PERCENT GIVEN THE UNCERTAINTIES OF THIS
RAPID CHANGE IN THE MODEL AND THE MIXED PCPN WOULD PERHAPS YEILD
AN INCH OR TWO OF SNOW. THE REST OF THE FCST IS ON TRACK.
PREV DISCUSSION... /ISSUED 533 AM CST SAT DEC 8 2012/
UPDATE...
AVIATION...
MVFR CIGS ARE EXPECTED IN SOME AREAS TODAY AND TONIGHT.
THE RUC MODEL...WHICH HAS BEEN PERFORMING WELL...SHOWS THE
MVFR/LOCAL IFR CIGS ACROSS NCNTL NEB LIFTING NORTH THIS AFTERNOON
WITH MVFR CIGS FILLING IN AGAIN TONIGHT AS AN ARCTIC FRONT MOVES
INTO WRN/NCNTL NEB.
MEANWHILE A WARM FRONT DEVELOPING ACROSS SRN NEB THIS MORNING WILL
LIFT NORTH DURING THE DAY TODAY PRODUCING ISOLATED RAIN AND SNOW
SHOWERS AND LOCAL MVFR CIGS. ADDITIONAL SCATTERED SNOW SHOWERS/MVFR
CIGS ARE EXPECTED TONIGHT ALONG AND BEHIND THE ARCTIC FRONT.
WINDS ALONG AND BEHIND THE FRONT WILL INCREASE TO 32025G35KT TONIGHT.
PREV DISCUSSION... /ISSUED 400 AM CST SAT DEC 8 2012/
SYNOPSIS...
EVENING HAND ANALYSIS OF THE H5 LEVEL REVEALS A BROAD LONGWAVE
TROUGH ENCOMPASSING MUCH OF THE CONTIGUOUS 48...WITH RIDGING OFF
BOTH THE WESTERN AND EASTERN COASTS. SEVERAL SHORTWAVES ARE SEEN
MOVING THROUGH THE BROAD TROUGH...WITH ONE NOW EAST OF THE UPPER
MISSISSIPPI VALLEY...AND THE NEXT APPROACHING THE NORTHERN/CENTRAL
HIGH PLAINS FROM THE WEST. AT THE SURFACE...AN AREA OF LOW PRESSURE
IS STARTING TO DEEPEN OVER CENTRAL MONTANA WITH HIGH PRESSURE
LOCATED OVER THE MISSOURI VALLEY. WHILE WINDS ARE FAIRLY LIGHT AND
VARIABLE AT THIS HOUR ACROSS THE CWA...FURTHER WEST ACROSS THE HIGH
PLAINS...SURFACE WINDS ARE STARTING TO TAKE ON A MORE SOUTHERLY
COMPONENT. TEMPERATURES EARLY THIS AM RANGE FROM A CHILLY 13
DEGREES FAHRENHEIT AT KLBF...TO AS WARM AS 30 AT KONL WHERE STRATUS
IS LOCKED IN PLACE.
DISCUSSION...
SHORT TERM...TONIGHT THROUGH 12Z TUESDAY. MAIN FORECAST CONCERNS
OVER THE NEXT 72 HOURS INVOLVES THE THREAT OF LIGHT SNOW...A RETURN
OF COLD TEMPERATURES...AND THE POTENTIAL OF ADVISORY CRITERIA WIND
SPEEDS.
MODELS CONTINUE TO SHOW GOOD AGREEMENT IN THE NEAR TERM IN WHICH THE
WESTERN SHORTWAVE TROUGH AND ASSOCIATED SURFACE LOW DEEPEN AND EJECT
EAST ACROSS THE NORTHERN PLAINS...DRAGGING A STRONG COLD FRONT
THROUGH THE CWA LATE TODAY/OVERNIGHT TONIGHT. THE STRONGEST OMEGA
CONTINUES TO BE SUGGESTED WELL NORTH OF THE CWA...IN CLOSE VICINITY
TO THE TROUGH AXIS...HOWEVER MOST NEAR TERM MODEL SOLUTIONS GENERATE
LIGHT QPF AHEAD OF A MID-LEVEL FGEN BAND WHERE WEAK THERMAL
ADVECTION AND A BRIEF PERIOD OF UPGLIDE MAY BE SUFFICIENT ENOUGH TO
SQUEEZE OUT A HUNDREDTH OR TWO OF AN INCH OF PRECIPITATION THIS
AFTERNOON. THE BETTER DYNAMICS FOR PRECIPITATION PRODUCTION ARRIVES
WITH THE MID LEVEL FRONTOGENETIC BAND LATE THIS
AFTERNOON/EVENING...HOWEVER FORECAST PROXIMITY SOUNDINGS FROM ACROSS
THE CWA SUGGEST THE LOWER LEVELS OF THE ATMOSPHERE WILL QUICKLY DRY
OUT AS STRONG COLD/DRY AIR ADVECTION SPILLS IN BEHIND THE PASSING
BOUNDARY. THE ENSEMBLES...AND DETERMINISTIC SOLUTIONS ALL HAVE
CONVERGED THAT AT MOST LESS THAN .05 OF AN INCH OF QPF WOULD BE
GENERATED...SO ONLY LOOKING FOR A DUSTING TO POSSIBLY A HALF OF AN
INCH ACROSS THE SANDHILLS AND POINTS SOUTHEAST WHERE ADDITIONAL LIFT
MAY BE GENERATED WITHIN THE VICINITY OF THE RIGHT ENTRANCE OF A
PASSING UPPER JET. ACROSS NORTHERN NEBRASKA...THE NEAR TERM
CONSENSUS IS SUGGESTING A PERIOD OF POSSIBLE WRAP AROUND AS THE
SURFACE LOW ADVANCES INTO WEST CENTRAL MINNESOTA...THE POTENTIAL OF
SLIGHTLY HEAVIER SNOW ACCUMULATION EXIST...BUT LESS THAN AN INCH
WOULD BE EXPECT AT BEST WITH THE SNOW FALLING OVERNIGHT TONIGHT.
THE SHORTWAVE QUICKLY ADVANCES EAST OVERNIGHT BRINGING AN END TO
PRECIPITATION CHANCES FOR THE FORESEEABLE FUTURE AS AN OVERALL LACK
OF KINEMATIC FORCING IS SUGGESTED IN THE SHORT AND LONG TERM
SOLUTIONS.
STRONG COLD AIR ADVECTION AND MODEST LOW LEVEL PRESSURE RISES WILL
FOLLOW THE SURFACE BOUNDARY PASSAGE OVERNIGHT TONIGHT. THE
PRESSURE RISES WILL HELP TIGHTEN THE SURFACE GRADIENT AND ALLOW FOR
GUSTY CONDITIONS EARLY ON SUNDAY. THE MODELS HAVE SHOWN A SLIGHT
NORTHWARD TREND IN THE TRACK OF THE SURFACE LOW...NOW ACROSS WEST
CENTRAL MINNESOTA. THIS TRACK FAVORS SLIGHTLY WEAKER SURFACE WINDS
THAN PREVIOUSLY ANTICIPATED. SO WILL KEEP WIND SPEEDS BELOW
ADVISORY CRITERIA...ESPECIALLY SINCE THE STRONGEST PRESSURE RISES
ARE EXPECTED DURING THE EARLY MORNING HOURS...DIURNALLY UNFAVORABLE
FOR ADVISORY CRITERIA WIND. BUT...WIDESPREAD SUB ZERO WIND CHILLS
WILL BE POSSIBLE...WITH THE POTENTIAL OF SOME OF THE LOWEST READINGS
APPROACHING MINUS TEN OR COLDER AS H9 TEMPERATURES FALL AS COLD AS
MINUS 12C ACROSS OUR NORTHERN ZONES. HIGHS ON SUNDAY WILL BE
CHILLY...WITH READINGS RANGING FROM THE UPPER TEENS ACROSS THE
NORTH...TO THE UPPER 20S ACROSS THE FAR SOUTHWEST. WE WILL NEED TO
WATCH LOW TEMPERATURES FOR MONDAY MORNING...AS ANY SNOWFALL WOULD
ALLOW READINGS TO PLUMMET...TO POSSIBLY BELOW 0F. WILL KEEP
FORECAST VALUES IN THE SINGLE DIGITS FOR NOW...AS WIDESPREAD
ACCUMULATING SNOW IS NOT ANTICIPATED. TEMPERATURES BEGIN TO MODERATE
SLOWLY MONDAY AFTERNOON AS WEAK WAA INFILTRATES FROM THE WEST IN
ADVANCE OF THE NEXT SHORTWAVE TROUGH.
LONG TERM...12Z TUESDAY AND BEYOND. THE NEXT WAVE PASSES THROUGH
EARLY TUESDAY...HOWEVER MOISTURE REMAINS IN QUESTION...AND KINEMATIC
FORCING REMAINS SOMEWHAT WEAK AND TO THE SOUTH...THUS CONFIDENCE IS
TOO LOW TO INTRODUCE POPS INTO THE FORECAST. OTHERWISE SHORTWAVE
RIDGING AND WAA TAKE HOLD THROUGH THE END OF NEXT WEEK...WITH
TEMPERATURES REMAINING NEAR TO SLIGHTLY ABOVE SEASONAL NORMS. THE
NEXT SIGNIFICANT TROUGH IS SHOWN TO ARRIVE ACROSS THE WEST LATE NEXT
WEEK...BUT WITH THIS EVENINGS MODEL RUNS...PRECIPITATION CHANCES
LOOK TO REMAIN WELL TO THE SOUTH AND WEST OF THE CWA.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...JACOBS
AVIATION/UPDATE1...CDC
UPDATE2...BROOKS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
309 PM CST SAT DEC 8 2012
.SHORT TERM...
QUITE CHALLENGING TODAY. MODELS KEEP TRACKING LOW A BIT FARTHER
SOUTH EACH RUN AND 12Z GFS AND LATEST RAP MODEL GO ALONG WITH 00Z
AND 12Z EURO IN HAVING LOW JUST NORTH OR NORTHEAST OF SIOUX FALLS
AT 12Z SUN. TRACK OF MID LEVEL LOW WOULD BRING HEAVIEST SNOW INTO
MOSTLY NORTHERN INTO NORTHEAST AND EAST CENTRAL SOUTH DAKOTA
TOWARD PERHAPS ST CLOUD AND THE NRN TWIN CITIES METRO AREA
OVERNIGHT INTO SUNDAY. THUS HEAVIEST SNOW NOW JUST CLIPS THE FAR
SOUTH FCST AREA IN WARNING AREA. FARTHER SOUTH TRACK GIVES A BIT
MORE CONFIDENCE NOW TO LEAVING STRETCH FROM VALLEY CITY TO FARGO
TO PARK RAPIDS IN ADVISORY FOR UP TO 4 INCHES WITH LESS FARTHER
NORTH.
NOW WILL ADD A FEW COUNTIES IN THE FAR NORTH ALONG ND/MB
BORDER TO WINTER WX ADVISORY TONIGHT AS AREA THERE RECEIVED 4
INCHES OF FLUFF ACCORDING TO SPOTTERS AND WILL EASILY BLOW AROUND
TONIGHT AS WINDS UP THERE INCREASE TO AROUND 20 MPH. PLUS WIND
CHILLS WILL DROP TO BELOW -25F LATER TONIGHT.
925 MB WINDS FARTHER SOUTH WILL INCREASE GREATLY 06Z TO 09Z FROM
NEAR GRAND FORKS SOUTH INTO ERN SD WITH 40-45 KTS THERE AND DUE TO
PRESSURE GRADIENT AND COLD ADVECTION SHOULD SEE GUSTS OVER 30 KTS
ESP IN SE ND IN THAT 09Z TO 18Z PERIOD. WINDS WILL HIT AFTER THE
MAIN SNOW AND WITH MAIN SNOW BEING LESS IN ALL BUT FAR SOUTH THAN
EARLIER THINKING STILL THINK ADV OK RIGHT NOW. COULD SEE BLIZZARD
CONDITIONS DEVELOP HOWEVER BUT QUITE IFFY ON THIS...MORE OF AN
OPEN COUNTRY THING VS IN TOWN AS MAIN SNOWFALL ITSELF IS JUST A
BIT SOUTH. EVE SHIFT CAN MONITOR.
SYSTEM WILL MOVE EAST SUNDAY AND SNOW AND WIND WILL
DIMINISH...SNOW FIRST THEN WIND. VERY COLD WITH 12Z-18Z WIND
CHILLS TO -30 IN THE FAR NORTHWEST FCST AREA. WILL LET MID SHIFT
ISSUE ANY WC HEADLINES. DIDNT WANT TO EXTEND WINTER WX HEADLINES
PAST 12Z SUN UP IN THE FAR NORTHWEST AS WINDS WILL DIMINISH THERE
FIRST.
HIGH PRESSURE WILL MOVE IN SUN NIGHT AND SOME SPOTS WILL GET INTO
THE NEGATIVE TEENS. CLOUDS WILL MOVE IN LATE SUN NIGHT INTO MONDAY
AND TUESDAY AS SEVERAL SHORT WAVES MOVE THROUGH BUT DOES LOOK
MAINLY DRY. COULD BE A FEW SPITS OF -SN BUT DID NOT MENTION YET.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
12 UTC GFS/ECMWF IN REASONABLE AGREEMENT NEXT WEEK...BOTH SHOWING
NORTHWEST FLOW ALOFT SHIFTING TO THE WEST/SOUTHWEST THROUGH THE
PERIOD. BEST CHANCE FOR SNOW WILL BE ALONG AND NORTH OF THE HIGHWAY
2 CORRIDOR ON WEDNESDAY AS A WEAK SHORT-WAVE MOVES ACROSS SOUTHERN
CANADA. THURSDAY INTO EARLY NEXT WEEKEND LOOK MAINLY DRY AS MAJORITY
OF ENERGY ALOFT GETS SHUNTED TO THE SOUTH WITH FOUR CORNERS TROUGH.
THIS FEATURE EJECTS NORTHEASTWARD AND INTO SOUTHEAST MN/WEST CENTRAL
WI BY SATURDAY...SO WILL NEED TO WATCH FOR ANY NORTHWARD OR WESTWARD
SHIFTS...REQUIRING AN INCREASE IN THE CURRENT ALL BLEND 20 POPS.
TEMPERATURES WILL BE SEASONABLE ON WEDNESDAY WITH HIGHS IN THE 20S
BEFORE A COOL-DOWN FOR THE LATTER HALF OF THE WEEK AFTER A COLD
FRONT MOVES THROUGH WEDNESDAY NIGHT. HIGHS THURSDAY/FRIDAY WILL
RANGE FROM THE SINGLE DIGITS ABOVE ZERO TO THE UPPER TEENS TO NEAR
20 DEGREES.
&&
.AVIATION...
MVFR/IFR CEILINGS WILL CONTINUE THIS EVENING AND OVERNIGHT...WITH
INCREASING SNOW CHANCES FROM WEST TO EAST AS A STRONG LOW PRESSURE
SYSTEM TRACKS ACROSS SD INTO WEST CENTRAL MN. EXPECT REDUCTIONS IN
VISIBILITY AS LOW AS 1/4 SM FROM SNOW AND WIND...ESPECIALLY BY 12
UTC SUNDAY AT VALLEY AIRFIELDS. WINDS WILL SHIFT TO THE NORTH
BETWEEN 00 AND 06 UTC THIS EVENING AND GUST TO 30 KTS OR MORE BY
SUNDAY MORNING. ATTEMPTED TO SIMPLIFY 18 UTC TAFS AS MUCH AS
POSSIBLE...BUT AMENDMENTS WILL BE NECESSARY. EXPECT SLOWLY
IMPROVING CONDITIONS LATE IN THE PERIOD FROM NORTHWEST TO
SOUTHEAST.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
SUNDAY FOR NDZ024-026>030-038-039.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY
FOR NDZ049-052-053.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
SUNDAY FOR NDZ006>008-014>016-054.
MN...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST
SUNDAY FOR MNZ001>003-013>017-022>024-027-028.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST SUNDAY
FOR MNZ029>032-040.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
SUNDAY FOR MNZ004-007.
&&
$$
RIDDLE/ROGERS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
330 PM EST SAT DEC 8 2012
.SYNOPSIS...
AN UPPER LEVEL TROUGH AND ITS ASSOCIATED SURFACE LOW WILL TRACK
NORTHEAST ACROSS THE EASTERN GREAT LAKES AND ST. LAWRENCE RIVER
VALLEY INTO TONIGHT. A COLD FRONT TRAILING THE LOW WILL PUSH
SLOWLY SOUTHEAST THROUGH THE REGION AND STALL OUT NEAR THE MASON-
DIXON LINE LATE TONIGHT AND EARLY SUNDAY...AS AN AREA OF HIGH
PRESSURE BUILDS INTO SOUTHEASTERN CANADA AND NORTHERN NEW ENGLAND.
THE FRONTAL ZONE WILL RETURN BACK TO THE NORTH AS A WARM FRONT
LATER SUNDAY INTO SUNDAY NIGHT...AS A MATURE CYCLONE DEVELOPS OVER
THE MIDWEST AND TRACKS NORTHEAST THROUGH THE GREAT LAKES. THIS
SYSTEM WILL BRING A STRONGER COLD FRONT THROUGH THE REGION ON
MONDAY.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
LATEST RUC DATA SHOWS THE WEAK ~1010MB SFC LOW OVR LK ONTARIO AS
OF 18Z. A COLD FRONT TRAILING THE LOW EXTENDS SWWD ACRS LK ERIE
AND N/CNTRL OH. AS THE LOW CONTINUES TO LIFT NEWD THRU THE REST
OF TODAY...EXPECT THE COLD FRONT TO MAKE SLOW SEWD PROGRESS INTO
THE NW MTNS BY 00Z.
LOW STRATUS AND FOG HAS BEEN REMARKABLY PERSISTENT OVR THE MID-
LWR SUSQ VLY...WITH THE LATEST 18Z OBS JUST NOW SHOWING SOME
SLIGHT IMPROVEMENT. THE LOW DECEMBER SUN ANGLE AND LGT/VRB WINDS
HAVE LIMITED MIXING PROCESSES THUS FAR...HOWEVER CONSENSUS OF THE
HIGH RES DATA STILL SUPPORTS A LATE AFTN BREAK-OUT INTO THE WARM
AIR /ESPECIALLY OVR THE LWR SUSQ VLY NEAR THE MD LINE/ WHICH
SHOULD ALLOW TEMPS TO QUICKLY SURGE INTO THE LOW 50S. AS EXPECTED
THE MILD AIR HAS REACHED THE CNTRL MTNS WITH AOO AND UNV IN THE
50S.
THE ALLEGHENIES WILL BE MOST SUSCEPTIBLE TO SHOWERS INTO THE
EVE...GIVEN WEAK UPSLOPE WITHIN CHANNEL OF DEEP MSTR/ABOVE NORMAL
PWATS LYING OVER THE REGION. SHORTWAVES MOVG QUICKLY NEWD IN THE
BROAD SWLY FLOW ALOFT WILL ALSO SUPPORT POCKETS OF ISENT LIFT
WHICH WILL CONTINUE TO PROMOTE SHOWER ACTIVITY IN LLVL CNVGNC ZONE
ALONG/AHEAD OF THE APPROACHING FNTL BNDRY. DESPITE THE HIGH MSTR
AVAILABILITY...QPF AMTS WILL REMAIN BE ON THE LGT SIDE.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH 6 AM SUNDAY/...
THE FRONTAL ZONE WILL SHIFT SEWD ACRS CENTRAL PA EARLY TONIGHT
AND BECOME QUASI-STNRY NEAR THE PA/MD BORDER BY EARLY SUNDAY.
SFC RIDGE AXIS EXTENDING SEWD FROM 1030MB HIGH OVR ONTARIO WILL
MOVE THRU NRN AREAS LATE TNT INTO EARLY SUNDAY...SUPPRESSING THE
CHC FOR RAIN TO THE FAR SRN TIER NEAR THE STALLED WAVY FNTL ZONE.
VEERING LLVL WINDS AND INC WAA SHOULD SUPPORT INCREASING POPS OVR
THE SRN TIER BY THE END OF THE SHORT TERM PERIOD. A NWLY FLOW
BEHIND THE FRONT WILL DIRECT COLDER AIR INTO NRN SXNS WITH TEMPS
FALLING NR THE FZG MARK BY DAYBREAK SUNDAY.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
SUNDAY MAY DAWN PTSUNNY ACROSS NORTHERN PA...BUT THAT WILL BE
SHORT-LIVED...AS FRONTAL ZONE SHIFTS NORTH. RAIN/DZ WILL BE ON THE
INCREASE FROM SW TO NE ONCE AGAIN DURING SUNDAY AS WARM AIR
ADVECTION BEGINS TO INCREASE WITH THE APPROACH OF THE NEXT
SHORTWAVE AND WARM FRONT LIFTING BACK TO THE NORTH. MDL DATA
SHOWING THE BEST FGEN FORCING LIFTING ACROSS THE SOUTHERN COUNTIES
BTWN 12Z-20Z...SO WILL PLACE HIGHEST POPS OF ARND 80 PCT IN THIS
AREA. ENSEMBLE MEAN QPF NOT VERY IMPRESSIVE SUNDAY...RANGING FROM
ARND A QUARTER INCH IN THE SOUTH...TO JUST A FEW HUNDREDTHS NORTH.
WITH THE HIGH RETREATING OFF TO OUR NE...LI PROGS SHOW A STRONG
COLD AIR DAMMING SIGNATURE SUPPORTING A CHILLY DAY WITH HIGHS ONLY
IN THE 40S. SOME THE THE HIGHER TERRAIN ACROSS CENTRAL PA MAY TOP
OUT IN THE U30S. WHILE THIS WILL BE COOLER THAN TODAY...IT WILL
STILL BE A BIT ABOVE NORMAL FOR THE SECOND WEEK OF DECEMBER.
MOST OF CENTRAL PA WILL BRIEFLY BREAK INTO THE WARM SECTOR ON
MONDAY...AS SFC LOW TRACKS NORTH OF THE STATE...PUSHING TEMPS WELL
ABV SEASONAL NORMS ONCE AGAIN. THE TRAILING COLD FRONT WILL SAG SE
THRU THE REGION ON MONDAY WITH AN AREA OF RAIN FALLING BEHIND
FRONT DUE TO AGEO THERMALLY DIRECT CIRCULATION ASSOC WITH JET
STREAK OVR THE EASTERN GRT LKS. ENS MEAN QPF MONDAY RANGES FROM 0.50
TO 0.75 INCHES OVER MUCH OF CENTRAL PA.
ENOUGH COLD AIR COULD ARRIVE BEHIND CD FRONT FOR A BRIEF CHANGE TO
SHSN MON NIGHT. HOWEVER...ANY ACCUMS WOULD LIKELY BE VERY LGT.
ALL MED RANGE GUIDANCE INDICATING SFC ANTICYCLONE BUILDS ACROSS
THE MID ATLANTIC AREA TUE-FRI...SUPPORTING A HIGH CONFIDENCE FCST
OF FAIR WX FOR THE REST OF THE WORK WEEK. GEFS MEAN 925TEMPS
SUPPORT HIGHS A BIT ABV NORMAL...WHILE CLEAR SKIES AND LGT WINDS
UNDER SFC HIGH SHOULD ALLOW NIGHT-TIME TEMPS TO FALL TO NEAR
NORMAL READINGS.
BUILDING MDL CONSENSUS ON ANOTHER LOW TRACKING TO OUR WEST OVR THE
WEEKEND. WILL INTRODUCE MENTION OF PRECIP FRI NITE AND SAT. COULD
BE ENOUGH LL COLD AIR FOR A BIT OF FZRA TO START BEFORE EVENTUAL
CHANGE TO RAIN.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
08/18Z - 09/18Z...
TROUBLE SPOT THIS AFTN REMAINS THE ERN TERMINALS WITH IFR/LIFR
CONDS SLOW TO IMPROVE. ALTHOUGH THE GUIDANCE HAS GENERALLY BEEN
TOO OPTIMISTIC...RECENT OBSERVATIONAL TRENDS ALONG WITH VIS SATL
DATA ARE SUPPORTING A GRADUAL IMPROVEMENT TO MVFR BY THIS EVE.
TO THE WEST...ANTICIPATE MVFR CONDS AT BFD AND JST TO GO BACK DOWN
TO IFR AS LOWER CIGS AND ONCL -SHRA MOVE INTO THE AREA AHEAD OF
COLD FRONT PRESSING SEWD FROM LK ERIE. UNV/AOO ENJOYING BRIEF VFR
BUT SHOULD TREND TO MVFR BASED ON UPSTREAM CIGS.
CONFIDENCE IN THE 18Z TAF PACKAGE IS SLIGHTLY BELOW AVG GIVEN THE
COMPLEX SFC PATTERN EVOLVING OVR CNTRL PA. FCST FOR LATE TNT INTO
EARLY SUNDAY LEANS TWD THE PESSIMISTIC SIDE OF THE GUIDANCE. THE
PATTERN FOR SUNDAY SUGGESTS A PROLONGED PERIOD OF LOW CIGS AND
VISBY WITH PERIODS OF -RA.
OUTLOOK...
SUN...MVFR/IFR WITH PDS OF RAIN.
MON...STG FROPA/WSHFT. MVFR/IFR BCMG MVFR/VFR CNTRL/EAST.
RAIN...POSS ENDING AS SNOW IN THE WEST.
MON NGT-TUE...MVFR WEST TO VFR EAST.
TUE-THUR...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...FITZGERALD
AVIATION...EVANEGO
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
145 PM EST SAT DEC 8 2012
.SYNOPSIS...
AN UPPER LEVEL TROUGH AND ITS ASSOCIATED SURFACE LOW WILL TRACK
NORTHEAST ACROSS THE EASTERN GREAT LAKES AND ST. LAWRENCE RIVER
VALLEY INTO TONIGHT. A COLD FRONT TRAILING THE LOW WILL PUSH
SLOWLY SOUTHEAST THROUGH THE REGION AND STALL OUT NEAR THE MASON-
DIXON LINE LATE TONIGHT AND EARLY SUNDAY...AS AN AREA OF HIGH
PRESSURE BUILDS INTO SOUTHEASTERN CANADA AND NORTHERN NEW ENGLAND.
THE FRONTAL ZONE WILL RETURN BACK TO THE NORTH AS A WARM FRONT
LATER SUNDAY INTO SUNDAY NIGHT...AS A MATURE CYCLONE DEVELOPS OVER
THE MIDWEST AND TRACKS NORTHEAST THROUGH THE GREAT LAKES. THIS
SYSTEM WILL BRING A STRONGER COLD FRONT THROUGH THE REGION ON
MONDAY.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
LATEST RUC DATA SHOWS THE WEAK ~1010MB SFC LOW OVR LK ONTARIO AS
OF 18Z. A COLD FRONT TRAILING THE LOW EXTENDS SWWD ACRS LK ERIE
AND N/CNTRL OH. AS THE LOW CONTINUES TO LIFT NEWD THRU THE REST
OF TODAY...EXPECT THE COLD FRONT TO MAKE SLOW SEWD PROGRESS INTO
THE NW MTNS BY 00Z.
LOW STRATUS AND FOG HAS BEEN REMARKABLY PERSISTENT OVR THE MID-
LWR SUSQ VLY...WITH THE LATEST 18Z OBS JUST NOW SHOWING SOME
SLIGHT IMPROVEMENT. THE LOW DECEMBER SUN ANGLE AND LGT/VRB WINDS
HAVE LIMITED MIXING PROCESSES THUS FAR...HOWEVER CONSENSUS OF THE
HIGH RES DATA STILL SUPPORTS A LATE AFTN BREAK-OUT INTO THE WARM
AIR /ESPECIALLY OVR THE LWR SUSQ VLY NEAR THE MD LINE/ WHICH
SHOULD ALLOW TEMPS TO QUICKLY SURGE INTO THE LOW 50S. AS EXPECTED
THE MILD AIR HAS REACHED THE CNTRL MTNS WITH AOO AND UNV IN THE
50S.
THE ALLEGHENIES WILL BE MOST SUSCEPTIBLE TO SHOWERS INTO THE
EVE...GIVEN WEAK UPSLOPE WITHIN CHANNEL OF DEEP MSTR/ABOVE NORMAL
PWATS LYING OVER THE REGION. SHORTWAVES MOVG QUICKLY NEWD IN THE
BROAD SWLY FLOW ALOFT WILL ALSO SUPPORT POCKETS OF ISENT LIFT
WHICH WILL CONTINUE TO PROMOTE SHOWER ACTIVITY IN LLVL CNVGNC ZONE
ALONG/AHEAD OF THE APPROACHING FNTL BNDRY. DESPITE THE HIGH MSTR
AVAILABILITY...QPF AMTS WILL REMAIN BE ON THE LGT SIDE.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH 6 AM SUNDAY/...
THE FRONTAL ZONE WILL SHIFT SEWD ACRS CENTRAL PA EARLY TONIGHT
AND BECOME QUASI-STNRY NEAR THE PA/MD BORDER BY EARLY SUNDAY.
SFC RIDGE AXIS EXTENDING SEWD FROM 1030MB HIGH OVR ONTARIO WILL
MOVE THRU NRN AREAS LATE TNT INTO EARLY SUNDAY...SUPPRESSING THE
CHC FOR RAIN TO THE FAR SRN TIER NEAR THE STALLED WAVY FNTL ZONE.
VEERING LLVL WINDS AND INC WAA SHOULD SUPPORT INCREASING POPS OVR
THE SRN TIER BY THE END OF THE SHORT TERM PERIOD. A NWLY FLOW
BEHIND THE FRONT WILL DIRECT COLDER AIR INTO NRN SXNS WITH TEMPS
FALLING NR THE FZG MARK BY DAYBREAK SUNDAY.
&&
.LONG TERM /SUNDAY THROUGH SATURDAY/...
SHOWERS WILL BE ON THE INCREASE FROM SW TO NE ONCE AGAIN BY THE
LATTER HALF OF SUNDAY AS WARM AIR ADVECTION BEGINS TO INCREASE
WITH THE APPROACH OF THE NEXT SHORTWAVE AND WARM FRONT LIFTING
BACK TO THE NORTH. SREF SHOWS PWATS SURGING TO 2-3 STD DEV ABOVE
NORMAL INTO THE OHIO VALLEY AND WESTERN PA BY LATE SUNDAY...ALL
AIMED AT THE LOCAL AREA.
WITH THE HIGH RETREATING OFF TO OUR NE...LI PROGS SHOW A STRONG
COLD AIR DAMMING SIGNATURE SUPPORTING A CHILLY DAY WITH HIGHS ONLY
IN THE 40S. WHILE THIS WILL BE COOLER THAN TODAY...IT WILL STILL
AVERAGE SEVERAL DEG ABOVE NORMAL FOR THE SECOND WEEK OF DECEMBER.
THE WAVY COLD FRONT WILL MOVE THROUGH THE AREA MONDAY WITH ANOTHER
WIDESPREAD SOAKING RAIN SLATED FOR THE AREA. MODELS ARE IN
REMARKABLE AGREEMENT ON TIMING...SUPPORTING A HIGH CONFIDENCE IN
THE IDEA OF VERY HIGH POPS FOR WHAT IS REALLY A DAY 3 FORECAST.
THE FRONT IS FCST TO BE EITHER OVER OR JUST EAST OF THE LOWER SUSQ
BY MONDAY EVENING...BRINGING A HALT TO THE STEADY RAIN. COLD AIR
WILL BE STACKED VERY CLOSE BEHIND THE FRONT WHICH COULD LEAD TO A
BRIEF CHANGEOVER TO SNOW...BUT LATEST INDICATIONS ARE FOR LITTLE
OR NO SNOW ACCUMS BEHIND THE SYSTEM.
SHORTWAVE RIDGING ALOFT ALLOWS FOR HIGH PRESSURE TO RAPIDLY FILL
IN BEHIND THE DEPARTING FRONTAL SYSTEM TUES-WED...BRINGING A
PROLONGED PERIOD OF DRY WEATHER...FOLLOWED BY A GRADUAL WARM UP AS
OUR FLOW EVENTUALLY TURNS WSW ALLOWING FOR A MODERATION IN TEMPS
BY THE END OF THE WEEK.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
08/18Z - 09/18Z...
TROUBLE SPOT THIS AFTN REMAINS THE ERN TERMINALS WITH IFR/LIFR
CONDS SLOW TO IMPROVE. ALTHOUGH THE GUIDANCE HAS GENERALLY BEEN
TOO OPTIMISTIC...RECENT OBSERVATIONAL TRENDS ALONG WITH VIS SATL
DATA ARE SUPPORTING A GRADUAL IMPROVEMENT TO MVFR BY THIS EVE.
TO THE WEST...ANTICIPATE MVFR CONDS AT BFD AND JST TO GO BACK DOWN
TO IFR AS LOWER CIGS AND ONCL -SHRA MOVE INTO THE AREA AHEAD OF
COLD FRONT PRESSING SEWD FROM LK ERIE. UNV/AOO ENJOYING BRIEF VFR
BUT SHOULD TREND TO MVFR BASED ON UPSTREAM CIGS.
CONFIDENCE IN THE 18Z TAF PACKAGE IS SLIGHTLY BELOW AVG GIVEN THE
COMPLEX SFC PATTERN EVOLVING OVR CNTRL PA. FCST FOR LATE TNT INTO
EARLY SUNDAY LEANS TWD THE PESSIMISTIC SIDE OF THE GUIDANCE. THE
PATTERN FOR SUNDAY SUGGESTS A PROLONGED PERIOD OF LOW CIGS AND
VISBY WITH PERIODS OF -RA.
OUTLOOK...
SUN...MVFR/IFR WITH PDS OF RAIN.
MON...STG FROPA/WSHFT. MVFR/IFR BCMG MVFR/VFR CNTRL/EAST.
RAIN...POSS ENDING AS SNOW IN THE WEST.
MON NGT-TUE...MVFR WEST TO VFR EAST.
TUE-THUR...MAINLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...LA CORTE
AVIATION...EVANEGO
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
529 PM EST SAT DEC 8 2012
.SYNOPSIS...
WARMING SOUTHWEST FLOW WILL PERSIST OVER THE REGION THIS WEEKEND.
SHOWER CHANCES ARE EXPECTED TO INCREASE BY MONDAY OUT AHEAD OF AN
APPROACHING COLD FRONT. COOLER HIGH PRESSURE WILL MOVE BACK INTO
THE CAROLIANS FOR MID WEEK.
&&
.NEAR TERM /THROUGH SUNDAY/...
500 PM UPDATE...A BAND OF LIGHT PRECIP HAS MOVED INTO THE UPSTATE SC
AND NE GEORGIA THIS AFTERNOON AND IT WILL CONTINUE TO PROGRESS EAST
ACROSS SC PEDIMENT THROUGH TONIGHT. PRECIP AMOUNTS SHOULD BE LIGHT
AND SOME LOCAL PATCHES OF FOG COULD ACCOMPANY THE BAND OF PRECIP.
THE LATEST RUC INDICATES THAT THE SHOWER ACTIVITY WILL DECREASE BY
LATE TONIGHT. ANOTHER AREAS OF FOG WILL DEVELOP ACROSS MUCH OF OUR
CWA TONIGHT INTO TOMORROW MORNING.
AS OF 200 PM...A PLUME OF GULF MOISTURE CAN BE SEEN ON VISIBLE
SATELLITE IMAGERY STREAMING WITHIN LLVL SWLY RETURN FLOW...WITH
LEADING EDGE OF STRATUS AND LGT SHWRS ENTERING THE WRN PORTIONS OF
THE CWFA. BOTH THE NAM AND GFS KEEP MOST OF THE ASSOCIATED ISENT
LIFT AND RH CONFINED TO THE SW NC MTNS AND UPR SAVANNAH VLY INTO
THIS EVENING...AS FLOW HAS ANTICYCLONIC CURVATURE AND HAS DOWNSLOPE
COMPONENT TO THE EAST. WITH THAT SAID...OVERALL INCREASING CLOUD
COVER AND POP IS EXPECTED ACRS THE ENTIRE AREA TNGT...AS A BRIEF
PERIOD OF ISENT LIFT AND RH TRANSLATES WEST TO EAST ACRS THE AREA.
TEMPS WILL BE 10-15 DEG ABOVE NORMAL OVERNIGHT...DROPPING ONLY INTO
THE MID 40S TO LWR 50S.
SUNDAY...GUIDANCE SHOWS THE CWFA COMPLETELY WITHIN THE WARM SECTOR
OF A DEVELOPING LOW PRES SYS OVR THE MID MS VLY. ISENT LIFT WEAKENS
AND DEEPER RH SHIFTS EAST. FCST SNDGS DO SHOW SOME SBCAPE...ESP ACRS
THE PIEDMONT...AS CLOUDS BREAK OUT AND TEMPS WARM INTO THE UPR 60S
TO NEAR 70. HOWEVER...A MID LVL INVERSION IS LIKELY TO CAP ANY
DEEPER CONVECTION. BESIDES LIMITED INSTBY...NO SIGNIFICANT MID OR
UPR LVL FORCING....AND LLVL LIFT WILL BE CONFINED TO SWLY UPSLOPE
FLOW IN THE SW NC MTNS. SO I HAVE POPS TAPERING OFF FROM CHC MTNS
AND SLGT CHC PIEDMONT IN THE MORNING TO ONLY A SLGT CHC IN THE NC
FOOTHILLS/NW PIEDMONT BY EARLY EVENING.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
AS OF 300 PM SATURDAY...THE MAIN FEATURE FOR THE SHORT RANGE
CONTINUES TO BE THE COLD FRONTAL PASSAGE LATE MONDAY OR MONDAY NITE.
THE GUIDANCE IN GENERAL SEEMS TO HAVE SLOWED SLIGHTLY WITH FROPA.
THAT SAID...THERE IS STILL SOME SPREAD IN THE TIMING OF THE FRONT.
THERE IS ALSO DISAGREEMENT ON THE DEVELOPMENT OF A SFC WAVE AND
WHETHER OR NOT IT MOVES ACROSS THE CWFA. THE GUIDANCE DOES AGREE
THAT ANY LINGERING LIGHT PRECIP SUNDAY EVENING WILL END BEFORE
MIDNIGHT AS LIFT DIMINISHES AND LOW LEVEL MOISTURE BECOMES SHALLOW.
HOWEVER...DEEPER MOISTURE AND FORCING ASSOCIATED WITH THE
APPROACHING FRONT WILL MOVE INTO THE MTNS AFTER MIDNIGHT SO PRECIP
CHC RETURNS BY DAYBREAK. WITH THE CONTINUED CLOUDS...SLY FLOW AND
HIGH THICKNESS VALUES...LOWS WILL BE 10 TO 20 DEGREES ABOVE NORMAL.
WITH THE FROPA TENDING TO SLOW...THIS ALSO SLOWS THE INCREASE IN
MOISTURE AND FORCING OUTSIDE OF THE MTNS. THEREFORE...DO NOT BRING
ANY CHC POP TO THE NC PIEDMONT AND ERN UPSTATE UNTIL LATE AFTERNOON
WITH CHC ACROSS THE FOOTHILLS AND WRN UPSTATE BY EARLY AFTERNOON.
THERE IS AGREEMENT THAT THE MTNS WILL SEE PRECIP ON MONDAY...BUT IT
IS SLOWED AS WELL...SO SHOW A SLOW INCREASE THRU LIKELY TO CAT POP
BY LATE IN THE DAY. THERE IS STILL LITTLE IN THE WAY OF SFC
INSTABILITY...BUT THERE LOOKS TO BE SOME WEAK ELEVATED INSTABILITY
AS LAPSE RATES INCREASE THRU THE DAY. THUNDER COULD DEVELOP JUST
ABOUT ANYWHERE EXCEPT THE NRN FOOTHILLS AND ALL BUT THE FAR SWRN NC
MTNS. THE FRONT LOOKS TO MOVE ACROSS THE CWFA MON NITE. SHEAR STILL
EXPECTED TO BE VERY STRONG WITH SOME HELICITY DEVELOPING. WITH THE
WEAK ELEVATED INSTABILITY...SVR QLCS STORMS COULD DEVELOP. IF THE
SFC LOW FORMS ALONG THE FRONT AND MOVES ACROSS THE I-85 OR SOUTH
CORRIDOR...THEN SVR CHC WOULD INCREASE AS LOW LEVEL FORCING AND
HELICITY COULD BE HIGHER. THIS COULD ALSO SLOW THE MOVEMENT OF THE
FRONT KEEPING SVR CHC INTO THE EVENING OR EVEN LATER. HAVE LIMITED
CAT POP TO THE MTNS FOR THE EVENING AND LIKELY ALL OTHER AREAS GIVEN
THE EXPECT TIMING UNCERTAINTY. THE GUIDANCE AGREES THAT LOWS MON
NITE AND PARTIAL THICKNESSES WILL BE HIGHER THAN PREV FCST. IN
ADDITION...GUIDANCE IS TRENDING AWAY FROM ANY TRADITIONAL NW FLOW
TYPE PRECIP. THEREFORE... HAVE REMOVED ANY SNOW MENTION LATE MON
NITE.
PRECIP SHUD DIMINISH TUE MORNING WITH ONLY SOME LINGERING ISOLATED
SHRA TUE AFTERNOON SOUTH OF I-85. HIGHS SHUD BE WARMER THAN EARLIER
EXPECTED AS WELL...NEAR NORMAL MTNS AND 5 TO 10 DEGREES ABOVE NORMAL
ELSEWHERE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AT 240 PM EST SATURDAY...THE AFOREMENTIONED FRONTAL BOUNDARY SHOULD
GRADUALLY GET A PUSH EAST TUESDAY NIGHT...AS A SECONDARY UPSTREAM
TROF INFLUENCES SENSIBLE WEATHER. THIS SHOULD CONCLUDE PRECIPITATION
CHANCES ACROSS OUR FORECAST AREA (FA). ALTHOUGH PRECIPITATION WILL
EITHER END OR EXIT...SOUNDING DATA SUGGESTS CLOUDS WILL LINGER MUCH
OF TUESDAY NIGHT...AND PLAN TO HOLD THAT LINE.
A LARGE AREA OF SURFACE HIGH PRESSURE WILL THEN SETTLE ACROSS OUR
FORECAST AREA (FA) WEDNESDAY AND THURSDAY...WHILE A FLAT 500 MB
RIDGE PREVAILS. THIS SHOULD SPELL QUIET WEATHER CONDITIONS DURING
MID WEEK.
AS WE REACH TOWARD THE START OF NEXT WEEKEND...THE H5 RIDGE WILL
HAVE SHIFTED OFF INTO THE ATLANTIC...AS WELL AS THE SURFACE HIGH.
SOUTHWESTERLY FLOW AT THE SURFACE AND ALOFT WILL BEGIN TO DRIVE
DEEPER MOISTURE INTO OUR REGION FRIDAY NIGHT...AND WILL PROBABLY
LAST THROUGH MUCH OF THE WEEKEND.
WARM AIR ADVECTION PRECIPITATION MAY BREAK OUT OVER THE NC MOUNTAINS
IN THE WEE HOURS SATURDAY MORNING. INCOMING CLOUDS SHOULD CAP
TEMPERATURES ABOVE FREEZING...SO AT THIS POINT WE ARE PAINTING
LIQUID AS THE PRECIPITATION TYPE. THE WARM AIR ADVECTION PATTERN
WILL THEN GRADUALLY ENCOMPASS MUCH OF OUR FA SATURDAY AND SATURDAY
NIGHT WITH A CHANCE OF SHOWERS. WILL HOLD POPS IN THE CHANCE FIELD
THIS FAR OUT...BUT WOULD NOT BE SURPRISED FOR A MORE ROBUST EPISODE.
A COLD FRONT WILL THEN BE APPROACHING / OR CROSSING / OUR REGION
LATE SATURDAY NIGHT OR BEYOND.
THE GFS IS VERY ROBUST WITH ITS PRECIPITATION FIELDS WHILE THE NEW
EUROPEAN MODEL...ALTHOUGH NOT AS BULLISH...HAS BROUGHT MORE QPF INTO
OUR FA AT THE START OF NEXT WEEKEND...COMPARED TO ITS 00Z RUN.
THERE SEEMS TO BE VERY LITTLE TO QUIBBLE WITH AS FAR AS TEMPERATURES
ARE CONCERNING...WITH SOME MINOR ADJUSTMENTS DURING THOSE PERIODS
WHEN CLOUDS ARE EXITING OR ENTERING THE FA.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
AT KCLT...VFR AT LEAST INTO THIS EVENING...WITH VARIABLE AMTS OF
CIRRUS AND SW WND THAT SHUD STAY UNDER 10 KTS. LATER TNGT...MOISTURE
WILL TRY TO WORK IN FROM THE WEST. GUIDANCE KEEPS ANY LOW CIGS
VFR...BUT SOME OF THE FCST SNDGS SUGGEST CIGS MAY BE MVFR.
ALSO...WITH MOIST SWLY BL FLOW...THERE MAY BE SOME VSBY RESTRICTIONS
TOWARD DAYBREAK. GUIDANCE IN GENERAL AGREEMENT ON IMPROVING
CONDITIONS BACK TO VFR BY MIDDAY SUNDAY.
ELSEWHERE...ANOTHER CHALLENGING SET OF TAFS. AN AREA OF MVFR STRATUS
WITH SOME -SHRA IS BEING ADVECTED INTO THE SW NC MTNS AND UPR
SAVANNAH VLY. THE CIGS SEEM TO BE LIFTING WITH THE HEAT OF THE
DAY...SO EXPECT THE UPSTATE SITES TO REMAIN VFR (ALTHO BRIEF PERIOD
OF MVFR CIGS IS POSSIBLE...ESP AT KAND). THINK THE LOW CLOUDS WILL
HAVE SOME TROUBLE CROSSING THE CENTRAL NC MTNS TO KAVL AND FURTHER
EAST...DUE TO DOWNSLOPE. TONIGHT...LIFT AND MOISTURE INCREASE...SO
EXPECTING INCREASE IN STRATUS COVERAGE. SOME OF THE MOS IS HITTING
FOG FAIRLY HARD IN LOCATIONS THAT HAD FOG THIS MORNING. I DON/T
THINK CONDITIONS WILL BE AS GOOD FOR WIDESPREAD FOG...BUT WILL KEEP
MENTION OF VSBY RESTRICTIONS LATE TNGT INTO SUNDAY MORNING.
CONDITIONS ARE EXPECTED TO IMPROVE AFTER DAYBREAK.
OUTLOOK...CONDITIONS ARE EXPECTED TO IMPROVE TO VFR ON SUNDAY. THEN
PATCHY FOG AND STRATUS WILL BE POSSIBLE AGAIN MONDAY MORNING. A
STRONG COLD FRONT WILL ENTER THE REGION ON MONDAY AND PUSH THRU
OVERNIGHT MONDAY NIGHT...ACCOMPANIED BY SHOWERS AND THUNDERSTORMS
ALONG WITH GUSTY WINDS.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...ARK/JOH
SHORT TERM...RWH
LONG TERM...TS
AVIATION...ARK