Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/06/12
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
751 PM MST WED DEC 5 2012
.UPDATE...MAIN ADJUSTMENT THIS EVENING WAS TO MOVE UP THE TIMING
OF PRECIPITATION IN THE MOUNTAINS. METARS EARLY THIS EVENING IN
KREMMLING INDICATED SOME LGT RAIN ALREADY FALLING. PCPN A PRODUCT
OF TWO PASSING JETS...ONE PASSING TO THE NORTH THROUGH SRN WY
THIS EVENING AND ANOTHER TO THE SOUTH BY 12Z THURSDAY MORNING. AS
A RESULT...HAVE OPTED TO INCREASE THE POPS OVER THE MOUNTAINS AND
HIGH VALLEYS THIS EVENING...AND ALSO SPREAD SLGT CHC POPS A LITTLE
FURTHER EAST ACROSS THE URBAN CORRIDOR THURSDAY MORNING.
&&
.AVIATION...GUSTY WLY WINDS AT KDEN AND KBJC THIS EVENING...SO
HAVE DELAYED THE ONSET OF THE LIGHTER WINDS UNTIL 05Z. OTHERWISE
NO SIGNIFICANT CHANGES. MAY NEED TO LOWER THE EXPECTED CIGS IN THE
MORNING AFTER 11Z BUT ALL DEPENDENT ON HOW MUCH MOISTENING OCCURS
IN THE MID AND UPPER LVLS. OVERALL HOWEVER THESE ADJUSTMENTS WILL
BE MINOR.
&&
.PREV DISCUSSION... /ISSUED 341 PM MST WED DEC 5 2012/
SHORT TERM...MODERATE WESTERLY FLOW CURRENTLY ALOFT ACROSS
COLORADO WITH DECENT PRESSURE FALLS AHEAD OF APPROACHING MID LEVEL
TROUGH. WINDS A BIT GUSTY ACROSS MOUNTAINS AND FOOTHILLS AS WELL
AS WESTERN SECTIONS OF URBAN CORRIDOR. 1500M GJT-DEN PRESSURE
GRADIENTS CURRENTLY AT 8.09 MB...HAS BEEN INCREASING SINCE 20Z.
LATEST RUC CROSS SECTIONS SHOWING CROSS MOUNTAIN FLOW 55 KTS AT
MOUNTAIN TOP THROUGH 02Z THEN DECREASING TO AROUND 40 KTS BY 04Z.
SO WINDS TO REMAIN GUSTY INTO THE EVENING HOURS ESPECIALLY ACROSS
MOUNTAINS AND ALONG FOOTHILLS...BEFORE DECREASING DURING THE
EVENING. OTHERWISE...MOISTURE TO CONTINUE TO INCREASE THROUGH THE
EVENING AS TROUGH MOVES INTO THE GREAT BASIN. THE DEEPER AND MORE
SUBSTANTIAL MOISTURE WILL BEGIN ADVECTING INTO THE MOUNTAINS AFTER
00Z. COMBINATION OF SOME COLDER AIR ALOFT AND INCREASING LIFT
WILL HELP WITH PRECIPITATION DEVELOPMENT ACROSS MOUNTAINS.
POTENTIAL FOR SOME BANDED PRECIPITATION ACROSS THE NORTHERN
MOUNTAINS AFTER MIDNIGHT...WILL KEEP THE HIGHER POPS THERE. SYSTEM
INITIALLY FAIRLY WARM...SO SNOW ACCUMULATIONS TO BE LIGHT. ACROSS
PLAINS...STILL SOME THREAT FOR LIGHT RAIN NEAR THE WYOMING BORDER
WHERE SOME BANDED PRECIP COULD OCCUR. OTHERWISE...THINGS LOOK DRY
OVERNIGHT. MODELS STILL SHOWING WEAK FRONT MOVING ACROSS AREA
AFTER MIDNIGHT WITH WINDS SHIFTING TO THE NORTH. SOME WEAK UPSLOPE
TO DEVELOP BEHIND FRONT...THOUGH 12Z MODEL CROSS SECTIONS SHOW
FAIRLY DRY LOW LEVELS. ON THURSDAY...MODEL CROSS SECTIONS SHOW
DECENT MOUNTAIN OROGRAPHICS WITH GOOD MOISTURE. THOUGH MOST OF THE
LIFT MOVES ACROSS WYOMING...THERE IS ENOUGH LIFT ACROSS THE
MOUNTAINS DURING THE MORNING TO HELP WITH SNOWFALL. THE LIKELY
POPS STILL LOOKING REASONABLE WITH UP TO 2 INCHES POSSIBLE...
MAINLY WEST FACING SLOPES. BY AFTERNOON...MODELS SHOW OROGRAPHICS
WEAKENING AS LIFT MOVES EAST OF THE AREA...SO SNOW CHANCES TO
DECREASE DURING THE AFTERNOON. ACROSS PLAINS...LIFT TO MOVE ACROSS
AREA DURING THE MORNING AS WEAK UPSLOPE CONTINUES. COULD SEE SOME
PRECIPITATION THROUGH 18Z...THOUGH LIFT AND UPSLOPE NOT VERY
IMPRESSIVE. LATEST MODELS CONTINUE TO SHOW SOME LIGHT QPF...SEEMS
TO BE OVERDONE. ALSO TEMPERATURES LOOK TO BE WARM ENOUGH FOR
RAIN...EXCEPT PERHAPS ALONG PALMER DIVIDE AND CHEYENNE RIDGE.
AFTER 18Z LIFT IS EAST OF AREA WITH SUBSIDENCE OVERHEAD. THIS
SHOULD NEGATE ANY PRECIP CHANCES. COOLER AIRMASS WILL BE OVER AREA
WITH TEMPERATURES ROUGHLY 15 TO 20 DEGREES COLDER THAN TODAY`S
READINGS ACROSS PLAINS WITH HIGHS IN THE UPPER 40S AND LOWER 5OS.
THIS IS STILL ABOVE NORMAL.
LONG TERM...A WEST-NORTHWEST FLOW ALOFT WILL PREVAIL THURSDAY
NIGHT THROUGH SATURDAY. MOISTURE EMBEDDED IN THE FLOW ALOFT WILL
BRING SOME LIGHT OROGRAPHIC SNOW TO THE MOUNTAINS AT TIMES
THURSDAY NIGHT THROUGH FRIDAY NIGHT. LAPSE RATES ARE JUST ALRIGHT
AT 5-7 C/KM...SO EXPECT SNOWFALL AMOUNTS TO STAY ON THE LIGHT
SIDE. A COLD FRONT WILL PUSH SOUTH ACROSS EASTERN COLORADO FRIDAY.
THIS WILL LOWER TEMPERATURES ANOTHER 5-10 DEGREES FROM THURSDAYS
HIGHS.
MOISTURE WILL INCREASE LATE FRIDAY NIGHT AND SATURDAY AS AN UPPER
LEVEL TROUGH MOVES SOUTHEAST OVER THE UTAH WYOMING AREA. EXPECT
SNOW TO INCREASE SATURDAY OVER THE MOUNTAINS. AT THE SURFACE...A
STRONG COLD FRONT WILL DROP SOUTH ACROSS EASTERN COLORADO SATURDAY
AFTERNOON. THIS WILL BRING GUSTY NORTHERLY WINDS BEHIND. AS
UPSLOPE WINDS AND MOISTURE SET UP EXPECT SNOW TO START SATURDAY
AFTERNOON OR EVENING. THE UPPER LEVEL TROUGH AXIS WILL PASS OVER
COLORADO SATURDAY NIGHT. DOWNWARD MOTION BEHIND THE TROUGH WILL
BRING THE SNOW TO AN END LATE SATURDAY NIGHT OR SNOW MORNING.
MOST OF THE MODELS SHOW IT WILL DRY OUT QUICKLY BEHIND THE FRONT
ON SUNDAY. WILL KEEP LOW POPS IN FOR THE EARLY PART OF THE SUNDAY
FOR THE POSSIBLILITY OF LINGERING SNOW. IF THE CLOUDS CLEAR OUT
SUNDAY NIGHT IT MAY GET QUITE COLD AND BE THE COLDEST NIGHT SO
FAR THIS SEASON.
FOR EARLY NEXT WEEK...AN ACTIVE NORTHWEST FLOW ALOFT WILL
PREVAIL. WEAK DISTURBANCES WILL PASS OVER THE STATE IN THIS
PATTERN. LITTLE TOO EARLY TO GET A GOOD TIMING ON THESE
SYSTEMS...SO WILL BROADDRUSH LOW POPS FOR THE MOUNTAINS. AT THIS
TIME...IT APPEARS THESE WAVES WILL BE TOO WEAK TO BRING SNOW TO
THE FRONT RANGE AND WILL KEEP THE MENTION OF SNOW OUT OF THE
FORECAST. TEMPERATURES WILL REMAIN NEAR TO BELOW NORMAL EARLY NEXT
WEEK. WOULD EXPECT WINDY CONDITIONS AT TIMES ALONG THE EAST
SLOPES UNDER THIS PATTERN.
AVIATION...WINDS TO REMAIN GUSTY THROUGH 02Z WITH GUSTS TO 20
KTS POSSIBLE AT DEN AND APA...AND UP TO 30 KTS AT BJC. WINDS TO
CONTINUE TO SHIFT TO THE NORTHWEST. AFTER 02Z WINDS TO WEAKEN AS
GRADIENT WEAKENS THOUGH MAY STILL BE A BIT GUSTY AT BJC. WEAK
FRONT TO MOVE ACROSS THE PLAINS AFTER 06Z WITH WINDS BECOMING
NORTHEAST. CEILINGS TO LOWER TO AROUND 6000 FEET AGL BY 12Z WITH A
SLIGHT CHANCE OF LIGHT RAIN. CONDITIONS WILL REMAIN VFR ALTHOUGH
ILS CONDITIONS POSSIBLE DUE TO CEILINGS. CONDITIONS TO IMPROVE BY
18Z WITH LIGHT EAST TO SOUTHEAST WINDS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....MEIER
AVIATION...COOPER
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
350 PM MST TUE DEC 4 2012
.SHORT TERM...MODERATE WEST TO NORTHWEST FLOW ALOFT ACROSS REGION
WITH SHORT WAVE RIDGE OVER GREAT BASIN. WEAK STABLE LAYER
CURRENTLY AT MOUNTAIN TOP WITH RADAR SHOWING SOME SIGNS OF A
MOUNTAIN WAVE. WINDS ALOFT NOT VERY STRONG WITH CROSS MOUNTAIN
FLOW 30-35 KTS AT MOUNTAIN TOP. SOME RECENT GUSTS TO 40 MPH BEING
REPORTED IN THE ESTES PARK AREA...BUT APPEAR LOCALIZED AND PERHAPS
TERRAIN DRIVEN. LATEST RUC CROSS SECTIONS INDICATE WINDS ALOFT
GRADUALLY DECREASING AFTER 02Z WITH CROSS MOUNTAIN WINDS AROUND 25
KTS NEAR RIDGE TOP AND ALONG HIGHER FOOTHILLS BY 06Z. THUS SHOULD
SEE WIND GUSTS GRADUALLY DECREASE DURING THE EVENING THOUGH THE
TERRAIN MAY KEEP THINGS A BIT GUSTY. SHOULD ALSO SEE A GRADUAL
INCREASE IN HUMIDITY AS TEMPERATURES COOL. LATEST SATELLITE LOOPS
SHOW CLOUDS HAVE THINNED ACROSS THE AREA WITH REMNANTS OF WAVE
CLOUD EAST OF URBAN CORRIDOR. MORE MOISTURE UPSTREAM...WITH
INCREASING HIGH LEVEL MOISTURE OVERNIGHT. WRF SYNTHETIC SATELLITE
IMAGERY SUGGESTING THE WAVE CLOUD REDEVELOPS ALONG FOOTHILLS AFTER
08Z. ON WEDNESDAY...FLOW ALOFT BECOMES WESTERLY AS RIDGE MOVES
SOUTH AND EAST OF COLORADO. CROSS SECTIONS SHOW MOISTURE
INCREASING ACROSS THE AREA WITH SOME LOWERING OF THE MOISTURE
ACROSS MOUNTAINS DURING THE MORNING...MAINLY NORTH OF INTERSTATE
70. MAY BE ENOUGH OROGRAPHICS TO GENERATE SOME SHOWERS ACROSS ZONE
31. OTHERWISE WINDS ALOFT TO INCREASE WITH CROSS MOUNTAIN FLOW AROUND
40 KTS AT MOUNTAIN TOP BY 18Z. THUS WINDS TO BE GUSTY ACROSS THE
MOUNTAINS AND HIGHER FOOTHILLS WITH LOCAL GUSTS AROUND 45 MPH
POSSIBLE DURING THE AFTERNOON. THE GUSTY WINDS WILL KEEP THE FIRE
DANGER ELEVATED ALONG THE FOOTHILLS...BUT HUMIDITY SHOULD REMAIN
ABOVE CRITICAL FIRE WEATHER THRESHOLDS. TEMPERATURE AND THICKNESS
PROGS AS WELL AS GUIDANCE SHOWING HIGHS IN THE 60S ACROSS THE
PLAINS. THIS LOOKING REASONABLE. CURRENT TEMPERATURE GRIDS IN LINE
WITH GUIDANCE...ONLY MINOR CHANGES NEEDED.
.LONG TERM...WESTERLY FLOW ALOFT WILL PREVAIL WEDNESDAY NIGHT AND
THURSDAY. WINDS WILL INCREASE WEDNESDAY NIGHT OVER THE MOUNTAINS AND
FOOTHILLS AS A COLD FRONT MOVES THROUGH THE STATE. A WEAK SHORT
WAVE TROUGH MAY BRING LIGHT SNOW TO THE MOUNTAINS AND PERHAPS SOME
LIGHT RAIN OVER EASTERN COLORADO THURSDAY.
THE WESTERLY JET WILL SINK SOUTH AS AN UPPER LEVEL TROUGH MOVES ONTO
THE PACIFIC NORTHWEST COAST. THIS WILL BRING COOLER CONDITIONS ON
FRIDAY WITH HIGHS IN THE 40S. ANOTHER WEAK DISTURBANCE EMBEDDED IN
THE FLOW ALOFT WILL BRING ANOTHER CHANCE FOR LIGHT PRECIPITATION.
THE UPPER LEVEL TROUGH OVER THE PACIFIC NORTHWEST WILL DIVE SOUTH
ACROSS THE GREAT BASIN SATURDAY AND END UP OVER THE SOUTHERN ROCKIES
SUNDAY. THIS WILL PUSH A STRONG COLD FRONT ACROSS COLORADO. STILL
SOME DIFFERENCE ON TRACK AND TIMING...BUT WILL BE ENOUGH ENERGY TO
BRING A PERIOD OF SNOW TO THE AREA. BIGGEST QUESTIONS ARE WHEN AND
HOW MUCH. APPEARS THE SNOW WILL BEGIN SOMETIME SATURDAY AND COME TO
AN END EARLY SUNDAY. MAY SEE SOME HEAVIER SNOW BANDS SATURDAY AS THE
JEST SINKS SOUTH ACROSS COLORADO. WILL CENTER THE HIGHEST POPS
AROUND SATURDAY NIGHT WHEN THE BEST CHANCE WILL BE ACCORDING TO THE
MODELS. COLD AIR WILL MOVE IN WITH THIS SYSTEM AND HIGHS WILL LIKELY
REMAIN BELOW FREEZING SUNDAY AND EARLY NEXT WEEK. NORTHWEST FLOW MAY
BRING LIGHT OROGRAPHIC SNOW EARLY NEXT WEEK...OTHERWISE JUST DRY AND
COOL CONDITIONS ARE EXPECTED FOR MONDAY AND TUESDAY.
&&
.AVIATION...LIGHT EASTERLY WINDS AT APA AND DEN TO WEAK AND BECOME
SOUTHERLY AS DRAINAGE PATTERN DEVELOPS. WINDS TO REMAIN WESTERLY
AT BJC. ON WEDNESDAY...WINDS TO BECOME NORTHWEST AFTER 18Z WITH
SPEEDS AROUND 8 KTS. HIGH LEVEL MOISTURE TO INCREASE AFTER 06Z
WITH THE POTENTIAL FOR A WAVE CLOUD ALONG FOOTHILLS BY 10Z. VFR TO
CONTINUE WITH CEILINGS UNLIMITED.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....MEIER
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
936 AM MST TUE DEC 4 2012
.UPDATE...
&&
.SHORT TERM...CURRENT FORECASTS STILL ON TRACK. WINDS TO BE ON THE
INCREASE DURING THE AFTERNOON...WITH BOTH NAM AND RUC CROSS
SECTIONS INDICATING CROSS MOUNTAIN FLOW AROUND 35 KTS AT MOUNTAIN
TOP BY 00Z. WINDS LOOKING MARGINAL FOR RED FLAG CONDITIONS DESPITE
THE LOW HUMIDITY. A FEW AREAS ALONG FOOTHILLS MAY REACH CRITERIA
FOR A SHORT TIME...MAINLY LOCATIONS WHERE TERRAIN WILL AID IN
FUNNELLING THE WINDS. STILL SOME THINNING OF WAVE CLOUD THROUGH
THE AFTERNOON...THEN REDEVELOPING OVERNIGHT WITH ARRIVAL OF DEEPER
MOISTURE.
.AVIATION...CURRENT TAF TRENDS LOOK REASONABLE...WILL CONTINUE FOR
THE UPCOMING ISSUANCE.
&&
.PREV DISCUSSION... /ISSUED 352 AM MST TUE DEC 4 2012/
SHORT TERM...CLOUDS WILL INCREASE FROM WEST TO EAST DURING THE
DAY AS WARMER AIR SPREADS OVER THE AREA. DESPITE THE HIGH
CLOUDINESS...THERE IS STILL SOME PRETTY DRY AIR AT LOW LEVELS. DEW
POINTS HAVE COME UP IN THE MOUNTAINS OVERNIGHT...MODEL GUIDANCE
SHOWS SURFACE DEW POINTS DROPPING AGAIN WITH MIXING DURING THE
DAY...BUT THEN RISING LATER IN THE DAY AS LOW LEVEL MOISTURE
FINALLY ARRIVES. I AM RATHER PESSIMISTIC ABOUT THE TIMING OF THIS
AND WILL HEDGE TOWARD LOWER VALUES THIS AFTERNOON. WINDS ALSO WILL
BE COMING UP LATE IN THE DAY...BUT FLOW ALOFT IS NOT THAT STRONG
WITH 20 KNOTS INCREASING TO 35 KNOTS AT 600 MB. ALSO A WEAK STABLE
LAYER...SO NOT EXPECTING WAVE AMPLIFICATION BUT THERE WILL BE SOME
STRONGER FLOW SPILLING DOWN THE HIGHER EAST SLOPES OF THE FRONT
RANGE. ALL IN ALL NOT MUCH OF A HIGH WIND THREAT AND MARGINAL ON
WIND AND ESPECIALLY HUMIDITY FOR A RED FLAG WARNING IN ZONE 35
ONLY...SO NO HIGHLIGHTS. MODELS SHOW SOME THINNING OF THE CLOUDS
THIS EVENING THEN DEEPER MOISTURE ARRIVING INTO THE MOUNTAINS LATE
TONIGHT...THOUGH THE GFS HOLDS THE BEST MOISTURE UP IN WYOMING.
THIS LOOKS REASONABLE AS THE SATELLITE PICTURES SEEM TO SHOW THESE
FEATURES...SOME LOWER CLOUDS IN NORTHERN NEVADA SO THIS MAY CLIP
THE PARK RANGE BUT WILL LEAVE THE CHANCE OF SNOW FOR DAYTIME ON
WEDNESDAY. FORECAST TEMPS ARE NEAR GUIDANCE AND LOOK PRETTY GOOD.
LONG TERM...ZONAL FLOW WILL BE OVER THE AREA ON WED WITH QUITE A
BIT OF MID AND HIGH LEVEL MOISTURE STREAMING ACROSS. COULD SEE A
SLIGHT CHC OF SHOWERS IN ZN 31 OTHERWISE WILL KEEP FCST DRY. HIGHS
ON WED WILL BE MILD WITH READINGS MAINLY IN THE 65 TO 70 DEGREE
RANGE ACROSS NERN CO. WINDS WILL BE GUSTY AT TIMES IN THE MTNS AND
NRN FOOTHILLS BUT SPEEDS SHOULD REMAIN BLO WARNING CRITERIA. FOR
WED NIGHT INTO THU MOISTURE WILL DEEPEN IN THE MTNS WITH SLIGHTLY
BETTER LAPSE RATES AS A WEAK UPPER LEVEL TROUGH MOVES ACROSS. THUS
SHOULD SEE A BETTER CHC OF SNOW IN THE MTNS ALTHOUGH ACCUMULATIONS
WILL STILL BE ON THE LIGHT SIDE. OVER NERN CO A WK CDFNT WILL
AFFECT THE AREA HOWEVER CROSS-SECTIONS SHOW ONLY WEAK UPSLOPE
FLOW. WILL LEAVE IN A SLIGHT CHANCE OF PCPN DUE TO PASSAGE OF WK
UPPER LEVEL TROUGH. SOUNDING DATA SHOWS SNOW LEVEL MAINLY ABOVE
7000 FEET SO WILL KEEP PCPN IN THE FORM OF RAIN WITH A MIXTURE IN
THE FOOTHILLS. HIGHS ON THU WILL BE COOLER WITH READINGS IN THE
50S ACROSS NERN CO. WINDS WILL REMAIN GUSTY IN THE MTNS AND
FOOTHILLS WED NIGHT INTO THU MORNING HOWEVER ONCE AGAIN SPEEDS
SHOULD STAY BLO HIGHLIGHT CRITERIA.
ON FRI LATEST DATA SHOWS A STRONGER JET MOVING INTO NRN IN WNW
FLOW ALOFT WITH ANOTHER WK UPPER LVL TROUGH. THUS COULD SEE
ANOTHER CHC OF SNOW IN THE MTNS WITH GUSTY WINDS. LAPSE RATES WILL
IMPROVE WITH THIS SECOND FEATURE SO ACCUMULATIONS MAY END UP BEING
BETTER WITH SOME ENHANCEMENT DUE TO POSITION OF UPPER LEVEL JET.
OVER NERN CO LATEST GFS SHOWS ANOTHER FNT MOVING INTO NERN CO BY
MIDDAY WITH SOME WK UPSLOPE FLOW WHILE THE ECMWF DOES NOT SHOW A
THIS FNT COMING IN UNTIL FRI EVENING. AM A LITTLE CONCERNED WITH
POSITION OF UPPER LVL JET AND DECENT LAPSE RATES ACROSS NERN CO
FRI AFTN INTO FRI EVENING. IF ENOUGH MOISTURE IS PRESENT COULD SEE
AT LEAST A SLIGHT CHC OF SHOWERS EITHER FRI AFTN OR FRI NIGHT
DEPENDING ON TIMING OF FNT. AS FOR HIGHS 850-700 MB TEMPS ARE
COOLER ON FRI SO WILL KEEP READINGS IN THE 40S ACROSS NERN CO.
FOR THE WEEKEND THE ECMWF AND GFS SHOW A STRONG UPPER LEVEL TROUGH
MOVING SE ACROSS THE AREA SAT NIGHT THROUGH SUN NIGHT WITH AN
ASSOCIATED STG CDFNT. AT THIS TIME IT APPEARS THE BEST CHC OF PCPN
WILL BE FROM SAT NIGHT THRU SUN. SOME HEAVIER SNOWFALL MAY OCCUR
SAT NIGHT INTO SUN MORNING IN THE FOOTHILLS AND ALONG THE FRONT
RANGE DUE TO INCREASING UPSLOPE FLOW AND POSITION OF UPPER LEVEL
JET WHICH MAY LEAD TO BANDED PCPN. MTNS SHOULD SEE SOME SNOW AS
WELL WITH EAST FACING SLOPES HAVING THE HIGHEST ACCUMULATIONS. AS
FOR HIGHS AHEAD OF THE STG CDFNT READINGS WILL BE IN THE 40S ON
SAT OVER NERN CO WHILE ON SUN READINGS MAY STAY IN THE 20S.
BY SUN NIGHT AND MON THE UPPER LEVEL TROUGH WILL MOVE SE OF THE
AREA WITH SNOW LIKELY ENDING SUN EVENING FOLLOWED BY DRY
CONDITIONS ON MON. TEMPS ON MON WILL REMAIN COLD WITH READINGS
STAYING IN THE 20S OVER NERN CO.
AVIATION...VFR CONDITIONS AND LIGHT WINDS TODAY...SHOULD KEEP A
SOUTHERLY COMPONENT AT KDEN/KAPA WITH EASTERLIES DEVELOPING DURING
THE DAY AT KBJC. BACK TO S/W DRAINAGE WINDS THIS EVENING.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....RPK
AVIATION...D-L
AREA FORECAST DISCUSSION...CORRECTED
NWS TAMPA BAY RUSKIN FL
315 AM EST TUE DEC 4 2012
.SYNOPSIS...
08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN AMPLIFYING UPPER LEVEL
PATTERN OVER THE CONUS THIS MORNING. NORTHERN STREAM FLOW CONSISTS
OF LONGWAVE RIDGING OVER THE PACIFIC COAST FOLLOWED DOWNSTREAM BY A
BROAD LONGWAVE TROUGH ACROSS THE MID-SECTION OF THE CONTINENT. THE
FLOW THEN FINALLY TURNS BACK TO THE NORTHEAST INTO LONGWAVE RIDGING
IN PLACE OVER THE EASTERN SEABOARD/WESTERN ATLANTIC. OUR FORECAST
AREA RESIDES AT THE BASE OF THIS RIDGE UNDER 582-584DM HEIGHTS. THE
PRESENCE AND INFLUENCE OF THIS UPPER RIDGING CAN AGAIN BE SEEN QUITE
WELL ON THE 04/00Z KTBW SOUNDING PROFILE WHICH SHOWS A WELL-DEFINED
SUBSIDENCE INVERSION AT 800MB. ANY SIGNIFICANT COLUMN MOISTURE IS
SUPPRESSED BENEATH THIS FEATURE.
AT THE SURFACE...1025MB HIGH PRESSURE REMAINS CENTERED OFF THE
CAROLINA COAST WITH A RIDGE AXIS EXTENDING BACK TO THE WEST THROUGH
SOUTHERN/CENTRAL GA/AL. GRADIENT FLOW ON THE SOUTHERN SIDE OF THIS
RIDGE AXIS IS PROVIDING AN EASTERLY BOUNDARY LAYER WIND AND AN
INFLUX OF ATLANTIC MOISTURE. DEEP LAYER SUPPRESSION IS CURRENTLY
STRONG ENOUGH THAT UNLIKE PREVIOUS NIGHTS...WE ARE NOT SEEING ANY
ISOLATED SPEED CONVERGENCE SHOWERS MIGRATING WESTWARD FROM THE FL
EAST COAST. THERE ARE STILL PERIODS OF LOWER STRATOCU MOVING EAST TO
WEST...ESPECIALLY DOWN TOWARD FT MYERS...AND THESE PERIODIC CLOUDS
WILL BE AROUND THROUGH THE DAY. TEMPERATURES ARE SEASONABLY WARM
WITH MOST LOCATIONS REPORTING IN THE 50S NORTH AND UPPER 50S TO
LOWER 60S SOUTH.
&&
.SHORT TERM (TODAY THROUGH THURSDAY)...
TODAY/TONIGHT...STACKED RIDGING WILL REMAIN THE DOMINANT PLAYER IN
OUR FORECAST THROUGH THE DAY. SHORTWAVE ENERGY WILL BEGIN TO
APPROACH THE REGION ALONG THE NORTHERN GULF COAST LATE IN THE
DAY...BUT THIS FEATURE SHOULD HAVE LITTLE IMPACT ON THE RIDGE UNTIL
VERY LATE TONIGHT AND WEDNESDAY. AT LEAST FOR TODAY...WILL START THE
DAY OFF WITH SOME PATCHY FOG...ESPECIALLY NORTH OF THE I-4 CORRIDOR.
THE LARGE SCALE SUPPRESSION AND DECENT DIURNAL MIXING WILL RESULT IN
ANOTHER WARM DAY REGION-WIDE WITH AFTERNOON HIGH TEMPERATURES IN THE
MIDDLE 70S TO AROUND 80 UNDER A MIX OF SUN AND CLOUDS. WILL BEGIN TO
SEE A SLOW BREAKDOWN IN HEIGHTS OVERNIGHT AS THE SHORTWAVE CONTINUES
IT EASTWARD ADVANCE TOWARD THE REGION. HOWEVER...PLENTY OF RESIDUAL
DRY AIR IN THE COLUMN WILL KEEP ANY MENTION OF RAIN OUT OF THE
FORECAST.
WEDNESDAY...MID/UPPER LEVEL FLOW BECOMES INCREASINGLY CYCLONIC IN
NATURE OVER THE FL PENINSULA THROUGH THE DAY. IN THE LOWER LEVELS
WILL CONTINUE TO SEE A GENERAL EASTERLY FLOW ON THE SOUTH SIDE OF
THE SURFACE RIDGE. A SLOW INCREASE IN SYNOPTIC SUPPORT FOR LIFT AND
COLUMN MOISTURE ALONG WITH THE FAVORED EASTERLY FLOW SHOULD INITIATE
THE DEVELOPMENT OF EAST COAST SPEED CONVERGENCE SHOWERS THAT THEN
TRANSLATE WESTWARD TOWARD THE REGION. THE MAJORITY OF THIS ACTIVITY
WILL LIKELY REMAIN ON THE EASTERN SIDE OF THE PENINSULA...BUT FEEL
THE SETUP IS FINALLY GOOD ENOUGH TO RE-INTRODUCE A SLIGHT CHANCE FOR
ISOLATED SHOWERS ACROSS MANY OF OUR ZONES. ANY SHOWERS THAT DO
OCCUR...ARE LIKELY TO BE LIGHT AND BRIEF IN NATURE. WILL SEE MORE IN
THE WAY OF CLOUDS FOR WEDNESDAY...BUT STILL ENOUGH SUNNY BREAKS TO
ALLOW FOR TEMPS TO REACH THE MID/UPPER 70S.
WEDNESDAY NIGHT/THURSDAY...THE SETUP NOW APPEARS MORE FAVORABLE FOR
SCT SHOWERS WITH THE SHORTWAVE PASSAGE THAN DURING PREVIOUS FORECAST
CYCLES...ESPECIALLY OVER THE SOUTHERN HALF OF THE AREA. FAIRLY
SHARP SHORTWAVE WILL APPROACH THE FL WEST COAST WEDNESDAY NIGHT AND
THEN CROSS OVER THE AREA DURING THE DAYLIGHT HOURS OF THURSDAY.
DECENT SWATH OF DEEP LAYER QG FORCING/SYNOPTIC SUPPORT OVERSPREADS
THE AREA THROUGH THURSDAY MORNING. IT ALSO NOW APPEARS THAT MORE IN
THE WAY OF COLUMN MOISTURE WILL BE COINCIDENT WITH THIS LIFT. ALL
THIS COMBINED WITH A STRENGTHENING EASTERLY FLOW SHOULD SUPPORT EAST
TO WEST FAST MOVING SHOWERS. WILL KEEP THIS ACTIVITY ISOLATED IN
NATURE FROM TAMPA BAY NORTHWARD ALONG THE NATURE COAST FOR NOW...BUT
INCREASING POPS TO CHANCE/SCATTERED RANGE FURTHER SOUTH IN LINE WITH
THE BEST Q-VECTOR CONVERGENCE AND DEEP LAYER MOISTURE. THURSDAY
AFTERNOON/EVENING WILL SEE THE SHORTWAVE AXIS AND RESULTING LIFT
PASSING THE AREA. INCREASING DEEP LAYER SUPPRESSION AND DRYING IN
THE WAKE OF THIS AXIS SHOULD END MOST OF THE SHOWER ACTIVITY OVER
THE FL WEST COAST BY THURSDAY NIGHT.
&&
.LONG TERM (FRIDAY THROUGH NEXT MONDAY)...
POTENT SHORT WAVE TROUGH WILL MOVE EAST OF THE AREA THURSDAY NIGHT
WITH CLEARING SKIES IN ITS WAKE. A LARGE AREA OF HIGH PRESSURE WILL
BRIDGE ACROSS A DECAYING FRONTAL BOUNDARY TO OUR NORTH. THERE WILL
BE NO REAL AIRMASS CHANGE SO WE WILL SEE LITTLE IF ANY CHANGE IN OUR
TEMPERATURES AND HUMIDITIES THROUGH THE EXTENDED PERIOD.
MODELS SHOW ENOUGH MOISTURE IN THE LOW LEVELS OF THE ATMOSPHERE TO
SUPPORT AT LEAST A SLIGHT CHANCE OF SHOWERS EACH DAY FROM SATURDAY
THROUGH MONDAY. THERE ARE NO SIGNIFICANT COLD FRONTS THROUGH AT
LEAST MONDAY...BUT SOME MODELS SUGGEST THE POSSIBILITY OF A WEAK
FRONTAL PASSAGE ON TUESDAY.
TEMPERATURES ARE LIKELY TO RUN SEVERAL DEGREES ABOVE NORMAL THROUGH
THE PERIOD...ESPECIALLY THE AFTERNOON HIGHS.
&&
.AVIATION...
SOME BRIEF PATCHY FOG POSSIBLE AROUND SUNRISE TODAY...OTHERWISE JUST
VFR CONDITIONS EXPECTED NEXT 24 HOURS.
&&
.MARINE...
HIGH PRESSURE TO THE NORTH OF THE AREA WILL CONTINUE AN EASTERLY
FLOW REGIME OVER THE EASTERN GULF OF MEXICO TODAY. NEAR CAUTIONARY
LEVEL WINDS OVER THE OFFSHORE WATERS EARLY THIS MORNING WILL
DIMINISH BY AFTERNOON. ANOTHER BRIEF SURGE IN WINDS TO NEAR
CAUTIONARY LEVELS IS POSSIBLE TONIGHT...ESPECIALLY SOUTH OF TAMPA
BAY. WINDS ARE FORECAST WELL BELOW HEADLINE CRITERIA DURING THE
MIDDLE PORTION OF THE WEEK AS THE LOCAL GRADIENT RELAXES. HIGH
PRESSURE WILL THEN BUILD ONCE AGAIN TO OUR NORTH FOR THE END OF THE
WEEK KEEPING AN EASTERLY FLOW REGIME IN PLACE.
&&
FIRE WEATHER...
SURFACE HIGH PRESSURE TO THE NORTH OF THE AREA WILL PROVIDE AN
EASTERLY FLOW AND ABUNDANT LOW LEVEL ATLANTIC MOISTURE THROUGH
WEDNESDAY. A COLD FRONT WILL APPROACH FROM THE NORTHWEST WEDNESDAY
AND WEDNESDAY NIGHT...BUT IS NOW EXPECTED TO DISSIPATE BEFORE
REACHING THE FL PENINSULA. A FEW SHOWERS ARE POSSIBLE WEDNESDAY INTO
THURSDAY ASSOCIATED WITH THIS SYSTEM...BUT NO SIGNIFICANT RAINFALL
IS FORECAST. HIGH PRESSURE WILL ONCE AGAIN BUILD TO OUR NORTH FOR
THE END OF THE WEEK. NO SIGNIFICANT FIRE WEATHER CONCERNS ARE
ANTICIPATED.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 79 61 77 60 / 0 0 20 20
FMY 79 61 78 61 / 10 10 20 30
GIF 79 57 79 58 / 0 10 20 20
SRQ 78 59 77 60 / 0 0 20 30
BKV 80 51 78 54 / 0 0 20 20
SPG 76 63 76 63 / 0 0 20 20
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
330 AM EST TUE DEC 4 2012
.DISCUSSION...
TODAY...PERSISTENCE FCST WILL BE THE GENERAL RULE AS A LARGE
H100-H70 ANTICYCLONE BLANKETING THE ERN SEABOARD CONTINUES TO
DOMINATE THE LCL WX PATTERN. CIRCULATION CENTERED OFF THE CAROLINA
COAST...DEEP ERLY FLOW TO CONTINUE. MAX TEMPS M-U70S
COAST...U70S/L80S INTERIOR.
LATEST SAT PICS/RAP ANALYSIS SHOWING A POCKET OF LOW LVL MOISTURE NE
OF THE NRN BAHAMAS EMBEDDED WITHIN THE ERLY FLOW...H100-H85 MEAN RH
ABV 80PCT...H100-H70 RH AOA 60PCT. AS THIS POCKET PUSHES ACRS THE
ISLANDS...EXPECT TO SEE A FEW SHRA BANDS DVLP IN THE CONVERGENT
EDDYS ON THEIR LEE SIDE. THESE SHOULD BE SUSTAINED BY THE WARM GULF
STREAM WATERS...WHILE THE STRENGTH/DEPTH OF THE LOW LVL ERLY FLOW
WOULD PUSH THEM ONSHORE S OF SEBASTIAN INLET. IMPACT WILL BE MINIMAL
AS THE LCL SOUNDINGS SHOW A SHARP H85-H70 SUBSIDENCE INVERSION
ASSOCD WITH THE RIDGE THAT WILL LIMIT VERTICAL MOTION BLO 10KFT
WHILE RAP ANALYSIS SHOWS LITTLE IN THE WAY OF MID/UPR LVL DYNAMIC
SUPPORT.
TONIGHT...THE RIDGE AXIS WILL BE SHUNTED E/SE THRU DAYBREAK WED AS A
FRONTAL TROF EXTENDING FROM THE GREAT LAKES TO THE SRN PLAINS PUSHES
TOWARD THE APPALACHIAN RANGE. H100-H70 WINDS WILL RESPOND BY VEERING
TO THE SE WHICH SHOULD ALLOW SHRAS TO SPREAD INTO SRN BREVARD/SERN
OSCEOLA...BUT AGAIN WITH MINIMAL IMPACT. INCREASED CLOUDS AND
INCREASING SRLY WIND COMPONENT SHOULD KEEP MIN TEMPS IN THE
U50S/L60S INTERIOR...L/M60S ALONG THE COAST.
WED-FRI...HIGH PRESSURE WILL WEAKEN AND MOVE EAST WEDNESDAY AHEAD
OF APPROACHING SHORTWAVE. ASSOCIATED SURFACE FRONT WILL WASH OUT TO
THE NORTH OF FLORIDA. HIGH PRESSURE TO THE NORTH WILL BRIDGE THE
REMAINS OF THE BOUNDARY THROUGH THE LATE WEEK. SOME INCREASE IN LOW
LEVEL MOISTURE AND TROFINESS ALOFT SHOULD ALLOW A FEW SHOWERS DURING
THIS TIME FRAME. HAVE LOW POPS MENTIONED WITH VALUES A LITTLE HIGHER
SOUTHERN COASTAL SECTIONS BY THURS NIGHT FRI WITH DEEPER MOISTURE
AND SOME CONVERGENCE DUE TO INVERTED TROF SETTING UP. TEMPS WILL BE
ON THE WARM SIDE FOR EARLY DEC WITH HIGHS MID/UPPER 70S...A FEW
SPOTS TOPPING 80 SOUTHERN INTERIOR. OVERNIGHT MINS RANGING FROM THE
MID/UPPER 50S WELL INLAND/VOLUSIA TO NEAR 60/LOWER 60S ALONG THE
COAST SOUTH OF THE CAPE.
SAT-MON...WILL CONTINUE WITH ABOVE NORMAL TEMPS THIS WEEKEND AS HIGH
TO THE NORTH SLIDES EAST OVER THE ATLANTIC AND LOW LEVEL FLOW VEERS
TO A MORE SE-S COMPONENT. SLIGHT CHANCE FOR SHOWERS WITH LINGERING
MOISTURE...WILL KEEP AS SLIGHT CHANCE/ISOLATED FOR NOW.
&&
.AVIATION...PREVAILING VFR ALL SITES UNLESS OTHERWISE NOTED. THRU
04/15Z...PTCHY MVFR VSBYS IN BR W OF KDAB-KOBE...BRIEF PDS OF IFR
VSBYS N OF I-4. BTWN 04/15Z-05/00Z...LCL MVFR CIGS/VSBYS IN ISOLD
PASSING SHRAS S OF KMLB-KGIF...LINE SHIFTING N TO KTIX-KISM AFT
15/00Z.
&&
.MARINE...TODAY-TONIGHT...HI PRES RIDGE CENTERED OFF THE CAROLINA
COAST WILL MAINTAIN A GENTLE TO MODERATE E/SE BREEZE ACRS THE LCL
ATLC THRU DAYBREAK WED. LATEST BUOY OBS SHOW THE SWELL IMPACTING THE
E FL COAST HAS SUBSIDED TO ARND 4FT WHICH THE CURRENT ERLY FLOW
SHOULD BE ABLE TO MAINTAIN. STEADY STATE CONDITIONS WITH SEAS 3-5FT
NEARSHORE AND 4-6FT OFFSHORE. WHILE THE LATTER MIGHT WARRANT A
CAUTIONARY STATEMENT...ALL OF THE OFFSHORE BUOYS ARE INDICATING THE
SEAS ARE MAINLY COMPRISED OF A LONG PD SWELL BTWN 8-10SEC WITH
SUSTAINED SFC WNDS GENERALLY BLO 15KTS. WILL HOLD OFF ON ANY
STATEMENTS.
WED-SAT...ONSHORE FLOW WILL PERSIST INTO THE WEEKEND. SEAS WILL
GENERALLY BE 3-5 FT...A FEW SPOTS UP TO 6 FEET WELL OFFSHORE. A FEW
SHOWERS WILL PERSIST FROM MID WEEK INTO THE WEEKEND.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 76 62 75 60 / 0 10 20 20
MCO 81 61 79 59 / 0 10 20 20
MLB 77 64 76 62 / 10 20 20 20
VRB 78 63 77 62 / 20 20 20 20
LEE 81 59 78 58 / 0 10 20 20
SFB 80 61 78 59 / 0 10 20 20
ORL 81 61 78 59 / 0 10 20 20
FPR 78 63 77 62 / 20 20 20 30
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...BRAGAW
LONG TERM....GLITTO
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
252 PM EST TUE DEC 4 2012
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
MAIN FORECAST PROBLEM THROUGH WEDNESDAY IS LIKELIHOOD FOR MEASURABLE
PRECIP. SHORT WAVE CURRENTLY LOCATED OVER SE OK/NRN TX ON WV IMAGERY
TRACKING EAST WITH CONSIDERABLE AMOUNT OF DEEP CONVECTION OCCURRING
AHEAD OF THE WAVE OVER THE LOWER MS VALLEY. MODELS HAVE VERY GOOD
AGREEMENT ON TIMING OF WAVE AND ASSOCIATED FRONT MOVING INTO THE FAR
NORTH LATE TONIGHT. MODELS ALSO IN STRONG AGREEMENT THAT VERTICAL
LIFT WILL WEAKEN TONIGHT AND WEDNESDAY WITH MUCH LOWER PRECIP
AMOUNTS AS THE SYSTEM MOVES INTO THE STATE. ALWAYS A CHALLENGE TO
FORECAST POPS IN THIS SITUATION AS WILL LIKELY SEE SCT LIGHT SHOWERS
ACROSS NORTHERN 3/4THS OF CWA BUT NOT CONFIDENT THAT ALL THESE
SHOWERS WILL PRODUCE MEASURABLE RAINFALL. HAVE KEPT POPS LATE
TONIGHT AND WED CONFINED TO LKLY CATEGORY OVER AREAS NORTH OF ATL
METRO AND 40-60 OVER METRO AND MUCH OF MIDDLE GA. NEAR-TERM MODELS
INCLUDING RADAR ASSIMILATING MODELS SUCH AS THE HRRR ARE INDICATING
BEST CHC FOR RAIN IN THE ATL METRO AROUND 6-8AM WITH LINGERING CHC
OF SCT LIGHT SHOWERS DURING THE DAY. USED MAV/MET BLEND FOR TEMPS
WITH A SLIGHT UPWARD ADJUSTMENT FOR MIN TEMPS TONIGHT.
BY WED...SUBSIDENCE BEHIND STRONG WAVE OVER THE NORTHEAST CONUS
YIELDS A EXPANSIVE 1035MB SFC HIGH OVER THE MIDWEST WHICH IS PROGGED
TO SPILL OVER AND DAM UP ALONG THE APPALACHIANS. SIGNIFICANT WEDGE
EVENT SHOULD RESULT BUT AS MENTIONED EARLIER...WE ARE FORTUNATE THAT
THE SOURCE AIRMASS FOR THIS HIGH IS NOT ARCTIC OR THAT COLD.
OTHERWISE WE MIGHT BE IN A WORLD OF HURT. OTHER THAN SOME COOL EAST
WINDS AND SOME PATCHY LIGHT RAIN AND FAIRLY WIDESPREAD CLOUDS...
SHOULD NOT BE TOO BAD FOR DECEMBER.
SNELSON
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
OVERALL...PREVIOUS FORECAST LOOKS TO BE ON TRACK. HAVE CONTINUED
WITH SLIGHT CHANCE POPS AS THE WEDGE REMAINS IN PLACE THROUGH LATE
WEEK WITH MODELS STILL INDICATING ISENTROPIC LIFT AND UPSLOPE FLOW
WILL SUPPORT LIGHT RAIN. MODEL GUIDANCE HAVE WARMED SLIGHTLY
DURING THE CAD EVENT...AND HAVE INCREASED MORNING LOW TEMPERATURES
SLIGHTLY FOR BETTER CONSISTENCY WITH THE SURROUNDING OFFICES. FOR
NOW...HAVE MADE A FEW VERY MINOR TWEAKS TO HIGH TEMPERATURE...BUT
OVERALL THINK THE MODELS ARE TOO WARM. THERE IS STILL ENOUGH
UNCERTAINTY WITH LATE WEEKEND AND EARLY WEEK MODEL SOLUTIONS THAT
HAVE OPTED NOT TO MAKE ANY SIGNIFICANT CHANGES AT THIS TIME.
HAVE INCLUDED THE PREVIOUS DISCUSSION BELOW.
31
ISSUED 356 AM EST TUE DEC 4 2012/
FRONT IMPACTING NORTH GEORGIA DURING THE SHORT TERM WILL BRIEFLY
STALL OUT ACROSS CENTRAL GEORGIA WEDNESDAY NIGHT INTO THURSDAY
MORNING. THIS BOUNDARY WILL PUSH FARTHER SOUTH AND WEST AS A WEDGE
FRONT ON THURSDAY DUE TO HYBRID CAD FROM A 1027 MB PARENT HIGH OFF
THE MID- ATLANTIC COAST. HAVE INCLUDED SLIGHT POPS FOR SHOWERS AS
THIS BOUNDARY INTERACTS WITH OVERRUNNING MOISTURE FROM THE SOUTH.
GUIDANCE SUGGESTS CONTINUED ISENTROPIC UPGLIDE ACROSS MUCH OF THE
AREA THROUGH FRIDAY SO HAVE KEPT SLIGHT CHANCE POPS FOR SHOWERS
FOR THE MAJORITY OF THE CWA AND MOSTLY CLOUDY SKIES DURING THIS
PERIOD. ANY ENHANCED SOLAR SHELTERING ACROSS THE CAD DOME MAY
REINFORCE THE WEDGE AND LEAD TO LATER EROSION THAN WHAT GUIDANCE
SUGGESTS... POSSIBLY LINGERING INTO THE WEEKEND. THIS WILL NEED TO
BE MONITORED CLOSER AS THIS FEATURE GETS INCLUDED IN THE SHORT
TERM MODELS.
BROAD SW FLOW ALOFT SETS UP FOR THE WEEKEND AND A STATIONARY FRONT
LOOKS TO BECOME SITUATED NW OF THE AREA ACROSS THE TN AND OHIO RIVER
VALLEYS. THE GFS AND ECMWF DIFFER GREATLY IN THE STRENGTH OF THE
BAROCLINITY AND EXPANSE OF THE MOISTURE FIELD WITH THIS
FEATURE...THOUGH SOME SHOWER DEVELOPMENT IS POSSIBLE ACROSS NORTH
GEORGIA IF ENOUGH MOISTURE EXISTS WITH SOME OROGRAPHIC ENHANCEMENT
DUE TO SOUTHERLY/SOUTHWESTERLY LOW LEVEL FLOW. HAVE THEREFORE KEPT
SLIGHT TO LOW END CHANCE POPS FOR SHOWERS ACROSS THE NORTHERN
PORTION THROUGH THE WEEKEND.
THE LATEST RUNS OF THE GFS AND ECMWF ARE IN DECENT AGREEMENT WITH
THE NEXT SIGNIFICANT PIECE OF ENERGY SWINGING ACROSS THE SOUTHWEST
CONUS AS AN UPPER CUTOFF LOW BY SUNDAY INTO MONDAY...THEN LIFTING
NORTHEASTWARD ACROSS THE CENTRAL PLAINS BY MONDAY NIGHT INTO
TUESDAY. A STRONG COLD FRONT ASSOCIATED WITH THE PHASED SFC LOW
PRESSURE SYSTEM MAY APPROACH THE FORECAST AREA FROM THE WEST BY
TUESDAY...HOWEVER THIS IS JUST BEYOND THE END OF THE FORECAST PERIOD
AND WILL ADJUST AS NECESSARY IN FUTURE UPDATES.
FORECAST INSTABILITY IS TOO LOW TO INCLUDE ANY THUNDER CHANCES IN
THE LONG TERM...THOUGH THE BEST SHOT LOOKS TO BE WITH POTENTIAL CFP
NEAR THE END OF THE FORECAST PERIOD EARLY NEXT WEEK.
BAKER
&&
.AVIATION...
18Z UPDATE...
PRIMARY CONCERN IS CHC FOR IFR CIGS AND SHRA LATE TONIGHT AND
WED MORNING. UNUSUAL WARM MOIST PATTERN WILL CONTINUE WITH CLOUDS
LIKELY TO PERSIST AHEAD OF FRONT. NOT A PATTERN FOR WIDESPREAD
PRECIP. SCT SHRA WILL REMAIN WEST OF MOST TAF SITES UNTIL 12Z.
COULD SEE IFR CIGS ASSOCD WITH PRECIP AND SOME RADIATIONAL COOLING
ABOVE MOIST LOW LEVELS PERSIST THROUGH 16Z OR SO. INSTABILITY WILL
BE NEAR ZERO SO NO THREAT FOR TSRA. FRONT WILL BECOME STATIONARY
ACROSS THE STATE WEDNESDAY SO SW TO WEST SFC WINDS WILL NOT BECOME
NW.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM CONFIDENCE ON IFR CIGS AND PRECIP PROBS WED MORNING.
HIGH CONFIDENCE ON ALL OTHER ELEMENTS.
SNELSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 53 68 50 57 / 40 50 30 20
ATLANTA 56 67 51 60 / 50 60 20 20
BLAIRSVILLE 51 63 44 55 / 60 60 20 20
CARTERSVILLE 53 66 48 61 / 60 60 20 20
COLUMBUS 55 74 54 69 / 30 30 10 20
GAINESVILLE 54 65 49 56 / 50 60 30 20
MACON 52 74 51 65 / 20 20 20 20
ROME 52 67 47 62 / 60 60 20 20
PEACHTREE CITY 51 67 48 62 / 50 60 20 20
VIDALIA 53 75 54 67 / 10 20 10 20
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SNELSON
LONG TERM....31
AVIATION...SNELSON
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
929 AM EST TUE DEC 4 2012
.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL PREVAIL THROUGH WEDNESDAY. A COLD FRONT
WILL MOVE ACROSS THE AREA WEDNESDAY NIGHT...FOLLOWED BY A WEDGE OF
HIGH PRESSURE FROM THE NORTH THROUGH LATE WEEK. A COASTAL TROUGH
WILL FORM OFFSHORE ON FRIDAY...THEN SHIFT INLAND OR DISSIPATE EARLY
IN THE WEEKEND. ATLANTIC HIGH PRESSURE WILL THEN PREVAIL THROUGH
EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AN EXTENSIVE MID-LEVEL CLOUD DECK REMAINS ANCHORED OVER THE AREA
THIS MORNING. RAP SOUNDINGS WOULD SUGGEST A GOOD PORTION OF THIS
CLOUD DECK WILL THIN AND MIX OUT OVER THE NEXT FEW HOURS AS
SURFACE TEMPERATURES SLOWLY WARM. IT LOOKS LIKE SIGNIFICANT
CLEARING WILL LIKELY NOT OCCUR UNTIL TEMPERATURES REACH THE UPPER
60S TO LOWER 70S PER THE 04/12Z CHS RAOB. STILL EXPECT A DECENT
AMOUNT OF SUN THIS AFTERNOON WITH PARTLY CLOUDY SKIES. HOWEVER...
AS TEMPERATURES WARM...EXPECT ANOTHER RATHER ROBUST CUMULUS FIELD
TO DEVELOP WITH THE BULK OF THE CLOUD COVER SHIFTING INLAND WITH
THE SEA BREEZE. HAVE ADJUSTED THE SKY COVER FORECAST TO MATCH THIS
THINKING. TEMPERATURES ARE POISED TO RISE RAPIDLY WHERE INSOLATION
INCREASES. HIGHS IN THE MID 70S AWAY FROM THE COAST LOOK
REASONABLE...BUT COULD EASILY SEE A FEW UPPER 70S IF CLOUDS BREAK
SOONER THAN EXPECTED.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
TONIGHT...ANOTHER ROUND OF FOG EXPECTED BUT COVERAGE AND INTENSITY
SHOULD BE LESS THAN PREVIOUS NIGHTS GIVEN THE INCREASE IN HIGH
LEVEL MOISTURE AND LOW-LEVEL WINDS AS A COLD FRONT BEGINS TO
APPROACH FROM THE WEST. LOWS SHOULD RANGE FROM THE LOWER 50S
INLAND TO MID/UPPER 50S AROUND THE COAST.
WEDNESDAY AND WEDNESDAY NIGHT...THERE WILL BE TWO DISTINCT TROUGHS
IN THE MID AND UPPER LEVELS OF THE ATMOSPHERE THAT WILL INFLUENCE
THE WEATHER ACROSS THE REGION. THE FIRST WILL BE A TROUGH WHICH
SLOWLY MOVES ACROSS THE NORTHERN GULF OF MEXICO...HELD BACK SOME BY
WEAK RIDGING ACROSS THE SOUTHEAST ATLANTIC. THE OTHER TROUGH WILL
MOVE ACROSS NEW ENGLAND AND IS DEEPER YET MORE PROGRESSIVE DUE TO
THE INFLUENCE OF THE POLAR JET. AT THE SURFACE...THIS TRANSLATES TO
MORE OF A BACKDOOR COLD FRONT WHICH DROPS SLOWLY THROUGH THE AREA
WEDNESDAY NIGHT.
SOMEWHAT ORGANIZED SHOWERS WILL APPROACH FROM THE NORTHWEST ON
WEDNESDAY...BUT BECOME CONSIDERABLY MORE DISORGANIZED AS THE FRONT
NEARS LATE WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT DUE A WESTERLY
FLOW IN PLACE AHEAD OF THE BOUNDARY WHICH SHOULD LIMIT DEEP
MOISTURE. THE FORECAST WILL INDICATE A 20-30 PERCENT CHANCE OF
SHOWERS ACROSS THE NORTH/NORTHWEST PORTION OF THE FORECAST AREA
WEDNESDAY AFTERNOON WITH RAIN-FREE CONDITIONS ELSEWHERE. ON
WEDNESDAY NIGHT...THE FORECAST WILL INDICATE A 20-30 PERCENT CHANCE
OF SHOWERS AS WELL...WITH THE HIGHEST PROBABILITIES ACROSS SOUTHEAST
SOUTH CAROLINA.
DESPITE INCREASING CLOUD COVER...THE DOWNSLOPE FLOW AND
COMPRESSIONAL HEATING ALONG AND AHEAD OF THE COLD FRONT SHOULD ALLOW
TEMPERATURES TO REACH HIGHS IN THE MID 70S AWAY FROM THE COAST ON
WEDNESDAY. LOWS WEDNESDAY NIGHT SHOULD BE IN THE LOWER TO MID 50S
DUE TO THE EXTENSIVE CLOUD COVER.
THURSDAY AND THURSDAY NIGHT...MODELS ARE IN PRETTY GOOD AGREEMENT
SHOWING A WEDGE OF HIGH PRESSURE BUILDING SOUTHWARD INTO THE AREA.
THERE APPEARS TO BE CONSIDERABLE LOW AND MID LEVEL MOISTURE TRAPPED
BENEATH THE INVERSION...WHICH SHOULD TRANSLATE TO MOSTLY CLOUDY
SKIES...ESPECIALLY ACROSS SOUTHEAST SOUTH CAROLINA. WEAK ISENTROPIC
ASCENT COULD SUPPORT A SLIGHT CHANCE OR LOW CHANCE OF LIGHT SHOWERS
JUST ABOUT ANYWHERE. THERE SHOULD BE A LARGE GRADIENT IN HIGH
TEMPERATURES...WHICH SHOULD RANGE FROM THE MID TO UPPER 50S IN THE
FAR NORTHWEST PORTION OF THE FORECAST AREA TO THE UPPER 60S NEAR THE
ALTAMAHA RIVER AND OTHER PORTIONS OF NORTH COASTAL GEORGIA. LOWS
THURSDAY NIGHT ARE TRICKY TO FORECAST AS WELL...WITH MID TO UPPER
40S EXPECTED IN MOST AREAS.
FRIDAY...AS HIGH PRESSURE CONTINUES TO SHIFT OFFSHORE AWAY FROM THE
NEW ENGLAND COAST...A COASTAL TROUGH IS EXPECTED TO DEVELOP JUST OFF
THE SOUTHEAST U.S. COAST. THERE COULD BE SOME ISOLATED SHOWERS ALONG
THE COAST IN ASSOCIATION WITH THE TROUGH...BUT THE BULK OF THE
PRECIPITATION IS EXPECTED TO REMAIN OFFSHORE. AS THE WEDGE SLOWLY
ERODES...HIGHS SHOULD REACH THE MID 60S ACROSS MUCH OF SOUTHEAST
SOUTH CAROLINA AND THE UPPER 60S TO NEAR 70 IN SOUTHEAST GEORGIA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
MEDIUM RANGE GUIDANCE IS IN FAIRLY GOOD AGREEMENT THROUGH THE LONG
TERM PERIOD...WHICH WILL FEATURE A BUILDING UPPER LEVEL RIDGE OVER
THE SOUTHEAST STATES. AT THE SURFACE...A COASTAL TROUGH IS EXPECTED
TO DAMPEN OUT AND/OR SHIFT INLAND FRIDAY NIGHT INTO SATURDAY...WITH
ATLANTIC HIGH PRESSURE THEN PREVAILING INTO EARLY NEXT WEEK. A COLD
FRONT IS THEN EXPECTED TO ADVANCE TOWARD THE AREA FROM THE NORTHWEST
ON TUESDAY.
THERE IS A SLIGHT CHANCE FOR SHOWERS AT JUST ABOUT ANY TIME THROUGH
MONDAY NIGHT AS A MOIST SOUTHERLY FLOW DEVELOPS OVER THE AREA. THE
PROBABILITY FOR SHOWERS WILL INCREASE INTO THE CHANCE CATEGORY ON
TUESDAY AHEAD OF THE APPROACHING FRONT. TEMPERATURES WILL BE WELL
ABOVE NORMAL UNDER THE INFLUENCE OF THE BUILDING RIDGE.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
EXTENSIVE MID LEVEL CLOUD COVER HAS KEPT FOG FROM FORMING AT THE
TERMINALS EARLY THIS MORNING...ALTHOUGH SOME BREAKS IN THE CLOUD
COVER NOTED JUST UPSTREAM OF KCHS COULD CAUSE A TEMPORARY/BRIEF
DROP IN VISIBILITIES TO MVFR OR LOWER LEVELS FROM ABOUT 13-14Z.
FOG IS POSSIBLE ONCE AGAIN TONIGHT...BUT WITH UNCERTAINTY IN
EXTENT OF POSSIBLE CLOUD COVER JUST HAVE PREVAILING 6SM IN THE TAF/S
AFTER 06Z. IF SKIES ARE RELATIVELY CLEAR...THEN MVFR OR LOWER
CONDITIONS ARE POSSIBLE LATE TONIGHT.
EXTENDED AVIATION OUTLOOK...LOW CEILINGS POSSIBLE WEDNESDAY NIGHT
AS A COLD FRONT MOVES THROUGH...THEN CONTINUING THROUGH THURSDAY
NIGHT AS A WEDGE OF HIGH PRESSURE BUILDS FROM THE NORTH. OUTSIDE
OF THESE PERIODS...MAINLY VFR.
&&
.MARINE...
TODAY AND TONIGHT...ATLANTIC HIGH PRESSURE WILL REMAIN IN CONTROL
THROUGH TONIGHT WITH A WEAK PRESSURE PATTERN SUPPORTING WINDS
MAINLY 10 KT OR LESS. SEAS DOMINATED BY ABOUT A 9 SECOND EAST
SWELL...RANGING FROM 2-3 FT NEARSHORE TO 3-4 FT BEYOND 20 NM.
POSSIBLY A BIGGER CONCERN THIS PERIOD WILL BE FOG ACROSS THE COOL
NEARSHORE WATERS AS A HUMID AIRMASS REMAINS IN PLACE.
WEDNESDAY THROUGH SUNDAY...ATLANTIC HIGH PRESSURE WILL GRADUALLY
WEAKEN AND DRIFT FARTHER OUT TO SEA WEDNESDAY AS A COLD FRONT
APPROACHES FROM THE NORTHWEST AND MOVES THROUGH THE MARINE ZONES
WEDNESDAY NIGHT. SURFACE HIGH PRESSURE WILL RAPIDLY BUILD A WEDGE
FROM THE NORTH THROUGH THURSDAY NIGHT. SMALL CRAFT ADVISORY
CONDITIONS ARE POSSIBLE ACROSS MOST OF THE COASTAL WATERS WEDNESDAY
NIGHT INTO THURSDAY NIGHT...AS THE PRESSURE GRADIENT TIGHTENS AND A
NORTHEAST SURGE DEVELOPS BEHIND THE COLD FRONT. THE CENTER OF HIGH
PRESSURE WILL THEN MOVE INTO THE ATLANTIC WATERS AND LINGER THROUGH
SUNDAY.
SEA FOG WILL BE A POSSIBILITY THROUGH WEDNESDAY...AS A MOIST AIR
MASS ADVECTS OVER THE COASTAL WATERS. WILL CONTINUE TO MENTION
PATCHY FOG ACROSS THE NEAR SHORE COASTAL WATERS AND CHARLESTON
HARBOR. IF FOG DOES INDEED FORM...IT COULD BE DENSE AT TIMES.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1120 PM CST MON DEC 3 2012
.AVIATION...
A COLD FRONT IS NOW WELL EAST OF ALL TERMINAL SITES IN EASTERN
IOWA AND NORTHWEST ILLINOIS. WINDS ARE NOW NORTHWESTERLY AROUND 8
TO 10 KTS...AND WILL REMAIN NEAR THAT RANGE THROUGH SUNSET TUESDAY
AFTERNOON. A HIGH CIRRUS OVERCAST REMAINS IN PLACE THROUGH THE
OVERNIGHT HOURS...BUT SHOULD BECOME TOTALLY CLEAR AT ALL SITES
EARLY TUESDAY MORNING. VISIBILITIES WILL BE EXCELLENT ABOVE 10
MILES...THROUGH THE PERIOD...AND BEYOND.
ERVIN
&&
.PREV DISCUSSION... /ISSUED 507 PM CST MON DEC 3 2012/
UPDATE...
A FORECAST UPDATE WAS SENT EARLY THIS PAST HOUR TO REFLECT A MUCH
LESS COVERAGE OF SHOWERS AND SHALLOW THUNDERSTORMS/CONVECTION. THE
EAST REMAINS THE MOST LIKELY AREA TO RECEIVE MEASURABLE RAIN...BUT
LOCATIONS WEST OF PRINCETON TO STERLING ARE LIKELY TO REMAIN WITH
TRACE AMOUNTS. AS FAR AS STRONG STORMS...WINDS ARE VEERING TO THE
SOUTHWEST...REDUCING SHEAR AT LOW LEVELS...THIS IS TRUE EXCEPT FOR
BUREAU AND PUTNAM COUNTIES...BUT BY THE TIME STORMS REACH
THERE...THEY MAY VEER AS WELL. WE REMAIN WATCH FULL...BUT FEEL THE
THREAT FOR A SEVERE EVENT IS VERY LOW AND CONFINED TO THE NEXT 1
HOUR...IN THE FAR EAST.
ERVIN
SYNOPSIS...
A COLD FRONT WAS PUSHING INTO CENTRAL IOWA WITH SOUTHERLY WINDS
TRANSPORTING UNSEASONABLY WARM AND HUMID AIR INTO THE DVN CWA.
RECORD HIGHS HAVE ALREADY BEEN SET OR TIED FOR DECEMBER 3 AT ALL
MAJOR CLIMATE SITES. TEMPERATURES WERE ALSO NEARING THE ALL-TIME
RECORD HIGHS FOR DECEMBER. CURRENT READINGS WERE IN THE MID 60S TO
LOWER 70S WITH DEW POINTS AROUND 60. SPC MESO ANALYSIS INDICATED
SBCAPES WERE 500 J/KG AND EFFECTIVE BULK SHEAR WAS 45 KTS EAST OF
THE MS RIVER. EXTENSIVE LOW CLOUDS WERE OVER THE CWA BUT SOME
BREAKS NOTED ON VISIBLE SATELLITE PICTURES. ELSEWHERE BEHIND THE
FRONT TEMPERATURES WERE IN THE 50S WITH DEW POINTS IN THE
TEENS...ALONG WITH SUNNY SKIES.
HAASE
SHORT TERM...TONIGHT AND TUESDAY...
FORECAST FOCUS ON CONVECTIVE TRENDS LATE THIS AFTERNOON/EARLY THIS
EVENING WITH COLD FRONT.
TONIGHT...LOW CLOUDS PUTTING A DAMPER ON THE CONVECTIVE THREAT BUT
WILL STILL MENTION SHOWERS LIKELY AND ISOLATED THUNDERSTORMS FROM
MAINLY ABOUT THE MS RIVER ON EAST INTO THIS EVENING. HRRR MESO
MODEL SEEMS REASONABLE. THE COLD FRONT SHOULD BE NEAR THE MS RIVER
ABOUT 6 PM AND WILL HAVE MOVED THROUGH ALL OF THE CWA BEFORE
MIDNIGHT SO WILL BE DRY AFTER MIDNIGHT. SKIES WILL CLEAR LATER
TONIGHT AS SUBSIDENCE BEHIND UPPER TROUGH SWINGS THROUGH. WILL BE
COLDER WITH MIN TEMPS IN THE MID 30S NW TO MID 40S SE.
TUESDAY...HIGH PRESSURE BUILDS INTO THE CWA WITH SUNNY SKIES AND
COOLER TEMPERATURES...BUT STILL WELL ABOVE NORMAL FOR EARLY DECEMBER.
EXPECT AFTERNOON READINGS IN THE 50S ACROSS THE CWA.
HAASE
LONG TERM...TUESDAY NIGHT THROUGH NEXT MONDAY...
ZONAL UPPER LEVEL FLOW TO CONTINUE THE WARMER THAN NORMAL
TEMPERATURES THROUGH THE WORKWEEK WITH PRECIPITATION CHANCES FOCUSED
ON A COLD FRONTAL PASSAGE THURSDAY. THE POTENTIAL FOR MUCH COLDER
TEMPERATURES AND POSSIBLE WINTRY PRECIPITATION IS STARTING TO LOOK
MORE LIKELY WITH THE ARRIVAL OF A MORE DYNAMIC PATTERN OVER THE
WEEKEND INTO EARLY NEXT WEEK.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...HIGH PRESSURE DROPPING SOUTHEAST
OUT OF THE NORTHERN PLAINS WILL BRING A COLDER AIRMASS INTO THE
REGION TUESDAY NIGHT. CLEAR SKIES...LIGHT WINDS...AND 850 MB
TEMPERATURES IN THE LOW SINGLE DIGITS SUPPORT LOWS FROM THE MID 20S
NORTH TO LOWER 30S SOUTH. WEDNESDAY WILL REMAIN RELATIVELY COOL
COMPARED TO THE RECENT WARMTH AS LIGHT SOUTHEAST WINDS OUT OF THE
DEPARTING HIGH LIMIT HIGHS TO THE UPPER 30S NORTH TO NEAR 50 IN THE
FAR SOUTH. HIGH LEVEL CLOUD COVER WEDNESDAY WELL OUT AHEAD OF THE
NEXT FAST MOVING SHORTWAVE WILL HOLD MINS TO THE 30S.
THE FASTER ECMWF AND GEM TIMING OF THURSDAY EVENING/S COLD FRONTAL
PASSAGE IS PREFERRED OVER THE SLOWER GFS IN THE FAST FLOW ALOFT. MODELS
HAVE BACKED OFF SOME ON THE EXTENT OF PREFRONTAL PRECIPITATION...AND
HAVE FOLLOWED BY CONFINING LOW CHANCES FOR RAIN SHOWERS TO MAINLY
THE AFTERNOON HOURS ACROSS THE NORTHWEST. OTHERWISE...IT WILL BE
ANOTHER DAY OF BRISK SOUTHERLY WINDS...CLOUD COVER AND MILD
TEMPERATURES AHEAD OF THE FRONT WITH HIGHS FROM THE UPPER 40S TO
LOWER 50S. FOLLOWING THE FASTER NON-GFS SOLUTIONS...THE FRONT SHOULD
PUSH WELL SOUTHEAST BY FRIDAY MORNING...ALLOWING A DRY NORTH TO
NORTHEAST LOW LEVEL FLOW OUT OF THE NEXT HIGH DROPPING INTO THE
NORTHERN PLAINS. HOWEVER...DUE TO THE INPUT OF THE SLOWER...MORE
NORTHERLY GFS FRONTAL SOLUTION...SLIGHT CHANCE POPS ARE CARRIED INTO
THE FRIDAY PERIOD. TEMPERATURES WILL BE NOTICEABLY COOLER AS HIGHS
RETURN TO THE 40S.
SATURDAY THROUGH MONDAY...LATEST MODEL SOLUTIONS GENERALLY AGREE ON
AN EVOLUTION TO A MORE AMPLIFIED UPPER LEVEL FLOW AS A BUILDING
RIDGE IN THE EASTERN PACIFIC INDUCES A LONGWAVE TROUGH DOWNSTREAM IN
THE WESTERN U.S. THIS SETS UP AN UPPER LEVEL SOUTHWEST FLOW OVER A
STALLED FRONTAL BOUNDARY THROUGH THE MID MS VALLEY...FAVORABLE FOR
MORE WINTRY TYPE SYSTEMS OVER THE LOCAL AREA. HOWEVER...DUE TO HIGH
MODEL VARIABILITY FROM RUN TO RUN AND BETWEEN MODELS...CONFIDENCE IN
DETAILS IN THESE PERIODS REMAINS LOW. OVER THE PAST FEW RUNS...THE
ECMWF APPEARS TO HAVE THE BEST CONTINUITY WITH ITS MORE PHASED
DEPICTION OF THE LEAD SHORTWAVES THAT COULD RESULT IN THE REGION/S
FIRST WINTER STORM SYSTEM TRACKING FROM THE SOUTHERN PLAINS INTO THE
GREAT LAKES FROM SATURDAY NIGHT THROUGH SUNDAY NIGHT. THE 12Z GFS
HAS A SIMILAR SURFACE LOW...ALTHOUGH HAS A SLIGHTLY FASTER AND MORE
NORTHERLY TRACK. FOR NOW...THE BLENDED MODEL APPROACH WILL KEEP AN
EXTENDED PERIOD OF SLIGHT TO LOW END CHANCE POPS FROM FRIDAY NIGHT
THROUGH MONDAY...WHICH WILL LIKELY BE NARROWED DOWN IN LATER
FORECASTS. ABOVE NORMAL TEMPERATURES ADVERTISED THROUGH THE WEEKEND
COULD END UP SEVERAL CATEGORIES TOO HIGH...ESPECIALLY FROM SUNDAY
INTO MONDAY.
SHEETS
CLIMATE...
RECORD HIGHS FOR DECEMBER 3...
MOLINE.........69 IN 1970
CEDAR RAPIDS...64 IN 1998
DUBUQUE........64 IN 1970
BURLINGTON.....71 IN 1970
MONTHLY RECORD HIGHS...
BURLINGTON.....73 12/04/1998
CEDAR RAPIDS...69 12/04/1998
DUBUQUE........67 12/04/1998, 24/1889
MOLINE.........71 12/04/1998
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1249 PM EST TUE DEC 4 2012
.SYNOPSIS...
ISSUED AT 306 AM EST TUE DEC 4 2012
A BROKEN LINE OF SHOWERS AHEAD OF A COLD FRONT IS MOVING ACROSS
LOWER MICHIGAN EARLY THIS MORNING. THE RAIN WILL MOVE OUT OF THE
AREA BY LATE MORNING. WE/LL SEE SOME SUNSHINE THIS AFTERNOON BUT
TEMPERATURES WILL BE MUCH COOLER THAN YESTERDAY. THERE IS A CHANCE
OF MIXED RAIN AND SNOW FROM THURSDAY THROUGH THE WEEKEND.
TEMPERATURES WILL BE NEAR NORMAL.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 306 AM EST TUE DEC 4 2012
FORECAST CONCERNS DEAL PCPN TRENDS THIS MORNING. OVERALL...THE
FORECAST HASN/T CHANGED MUCH.
REGIONAL RADAR SHOWS A BROKEN BAND OF SHOWERS STRETCHING FROM NRN
LAKE HURON SWWD TO NEAR ST LOUIS. THIS PCPN IS ALIGNED ALONG THE
COLD FRONT WHICH IS PUSHING THROUGH THE CWA ATTM. LATEST IR LOOP
SHOWS COOLING CLOUD TOPS OVER ILLINOIS. THIS IS LIKELY IN RESPONSE
TO A WAVE ON THE SRN PORTION OF THE FRONT. HRRR SUGGESTS WE/LL SEE A
LARGER AREA OF PCPN MOVE INTO THE SRN/SE CWA PRIOR TO SUNRISE AS THE
WAVE MOVES NEWD. THIS JUST APPEARS TO BE RAIN...LIGHTNING REMAINS
WELL SW OF THE GREAT LAKES. PCPN WILL END FROM NW TO SE THIS
AFTERNOON AS THE WAVE MOVES MOVES THROUGH.
A SECONDARY COLD FRONT WILL MOVE SEWD THROUGH LOWER MICHIGAN
TONIGHT. WE MAY BRIEFLY SEE A FEW SHSN DEVELOP ALONG THE LAKE SHORE
NORTH OF HOLLAND BUT THEY WON/T AMOUNT TO MUCH AND WILL QUICKLY FADE
BY WEDNESDAY MORNING AS CORE OF THE COLD AIR MOVES EAST. HIGH
PRESSURE WILL SETTLE OVER THE CWA WEDNESDAY.
.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 306 AM EST TUE DEC 4 2012
CHALLENGING FORECAST IN THE EXTENDED AS MODEL CONSISTENCY HAS
BEEN POOR THE LAST COUPLE DAYS HANDLING THE DETAILS OF AN INVERTED
TROUGH/SFC WAVE MOVING ALONG THE FRONT STALLED ACROSS THE OHIO
VALLEY...AND A MORE SIGNIFICANT STORM EARLY NEXT WEEK.
WENT WITH LOW CHANCE OR SLIGHT CHANCE POPS EARLY IN THE PERIOD WITH
LOW CONFIDENCE ON DETAILS OF WHEN AND WHERE BEST CHANCES FOR PRECIP
WITH BE. P-TYPE IS ALSO A TOUGH CALL AS THERMAL PROFILES SUGGEST MIX
NORTH AND RAIN SOUTH.
A HIGHER IMPACT EVENT IS EXPECTED NEXT WEEK AS STRONG UPPER TROUGH
MOVES INTO THE ROCKIES WITH SFC LOW FORMING OVER THE PLAINS AND
HEADING FOR LOWER MICHIGAN. AGAIN CONFIDENCE IS LOW ON TIMING DUE TO
MODEL DIFFERENCES AND INCONSISTENCY...BUT A MIXED PRECIP TO RAIN
THEN OVER TO SNOW SCENARIO IS POSSIBLE EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1249 PM EST TUE DEC 4 2012
VFR CONDITIONS PREVAIL ACROSS SOUTHWEST LOWER MICHIGAN AS OF
1730Z. THE COLD FRONT AND RAIN ASSOCIATED WITH IT ARE NOW OFF TO
THE EAST AND SOUTH OF THE AREA. DRIER AIR IS WORKING INTO
SOUTHWEST LOWER MICHIGAN. VFR CONDITIONS ARE EXPECTED INTO THE
EVENING HOURS AS THE MID AND HIGH CLOUDS SLOWLY CLEAR TO THE
SOUTHEAST.
FOCUS SHIFTS TOWARD COLDER AIR SLIDING IN ON NORTHWEST WINDS AND
THE CHANCE FOR MVFR CLOUDS DEVELOPING TONIGHT AS THE COLD AIR
RIDES OVER LAKE MICHIGAN. FEEL LAKE CLOUDS WILL DEVELOP AND PUSH
INTO KMKG THIS EVENING AND SWEEP SOUTH AND EAST WITH TIME. BY 07Z
OR SO...THE MVFR STRATOCUMULUS DECK SHOULD BE OVER ALL THE TAF
SITES. CEILINGS OVER AROUND 3000FT WILL PERSIST INTO THE MIDDAY
HOURS OF WEDNESDAY. AT THIS POINT THE MOISTURE LOOKS TO SHALLOW
FOR ANY SNOW SHOWER ACTIVITY.
&&
.MARINE...
ISSUED AT 306 AM EST TUE DEC 4 2012
COLD ADVECTION WILL INCREASE WAVE HEIGHTS TODAY INTO WEDNESDAY. WE
EXTENDED THE SCA THROUGH THE AFTERNOON WEDNESDAY.
&&
.HYDROLOGY...
ISSUED AT 306 AM EST TUE DEC 4 2012
NO HYDRO ISSUES THIS MORNING QPF LESS THAN A QUARTER INCH IS
EXPECTED FROM SHOWERS ALONG THE COLD FRONT THIS MORNING.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EST WEDNESDAY FOR LMZ844>849.
&&
$$
SYNOPSIS...93
SHORT TERM...93
LONG TERM...OSTUNO
AVIATION...DUKE
HYDROLOGY...93
MARINE...93
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
619 AM EST TUE DEC 4 2012
.SYNOPSIS...
ISSUED AT 306 AM EST TUE DEC 4 2012
A BROKEN LINE OF SHOWERS AHEAD OF A COLD FRONT IS MOVING ACROSS
LOWER MICHIGAN EARLY THIS MORNING. THE RAIN WILL MOVE OUT OF THE
AREA BY LATE MORNING. WE/LL SEE SOME SUNSHINE THIS AFTERNOON BUT
TEMPERATURES WILL BE MUCH COOLER THAN YESTERDAY. THERE IS A CHANCE
OF MIXED RAIN AND SNOW FROM THURSDAY THROUGH THE WEEKEND.
TEMPERATURES WILL BE NEAR NORMAL.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 306 AM EST TUE DEC 4 2012
FORECAST CONCERNS DEAL PCPN TRENDS THIS MORNING. OVERALL...THE
FORECAST HASN/T CHANGED MUCH.
REGIONAL RADAR SHOWS A BROKEN BAND OF SHOWERS STRETCHING FROM NRN
LAKE HURON SWWD TO NEAR ST LOUIS. THIS PCPN IS ALIGNED ALONG THE
COLD FRONT WHICH IS PUSHING THROUGH THE CWA ATTM. LATEST IR LOOP
SHOWS COOLING CLOUD TOPS OVER ILLINOIS. THIS IS LIKELY IN RESPONSE
TO A WAVE ON THE SRN PORTION OF THE FRONT. HRRR SUGGESTS WE/LL SEE A
LARGER AREA OF PCPN MOVE INTO THE SRN/SE CWA PRIOR TO SUNRISE AS THE
WAVE MOVES NEWD. THIS JUST APPEARS TO BE RAIN...LIGHTNING REMAINS
WELL SW OF THE GREAT LAKES. PCPN WILL END FROM NW TO SE THIS
AFTERNOON AS THE WAVE MOVES MOVES THROUGH.
A SECONDARY COLD FRONT WILL MOVE SEWD THROUGH LOWER MICHIGAN
TONIGHT. WE MAY BRIEFLY SEE A FEW SHSN DEVELOP ALONG THE LAKE SHORE
NORTH OF HOLLAND BUT THEY WON/T AMOUNT TO MUCH AND WILL QUICKLY FADE
BY WEDNESDAY MORNING AS CORE OF THE COLD AIR MOVES EAST. HIGH
PRESSURE WILL SETTLE OVER THE CWA WEDNESDAY.
.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 306 AM EST TUE DEC 4 2012
CHALLENGING FORECAST IN THE EXTENDED AS MODEL CONSISTENCY HAS
BEEN POOR THE LAST COUPLE DAYS HANDLING THE DETAILS OF AN INVERTED
TROUGH/SFC WAVE MOVING ALONG THE FRONT STALLED ACROSS THE OHIO
VALLEY...AND A MORE SIGNIFICANT STORM EARLY NEXT WEEK.
WENT WITH LOW CHANCE OR SLIGHT CHANCE POPS EARLY IN THE PERIOD WITH
LOW CONFIDENCE ON DETAILS OF WHEN AND WHERE BEST CHANCES FOR PRECIP
WITH BE. P-TYPE IS ALSO A TOUGH CALL AS THERMAL PROFILES SUGGEST MIX
NORTH AND RAIN SOUTH.
A HIGHER IMPACT EVENT IS EXPECTED NEXT WEEK AS STRONG UPPER TROUGH
MOVES INTO THE ROCKIES WITH SFC LOW FORMING OVER THE PLAINS AND
HEADING FOR LOWER MICHIGAN. AGAIN CONFIDENCE IS LOW ON TIMING DUE TO
MODEL DIFFERENCES AND INCONSISTENCY...BUT A MIXED PRECIP TO RAIN
THEN OVER TO SNOW SCENARIO IS POSSIBLE EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 618 AM EST TUE DEC 4 2012
RAIN WILL CONTINUE FROM AZO TO LAN THIS MORNING WITH SOME MVFR
CONDITIONS PERSISTING THERE UNTIL AROUND 16Z. JXN WILL SEE SOME
MVFR AND EVEN IFR CONDITIONS AS THE RAIN WILL BE SLOW TO MOVE
EAST. ALL LOCATIONS SHOULD BE VFR BY THIS AFTERNOON AND EVENING.
&&
.MARINE...
ISSUED AT 306 AM EST TUE DEC 4 2012
COLD ADVECTION WILL INCREASE WAVE HEIGHTS TODAY INTO WEDNESDAY. WE
EXTENDED THE SCA THROUGH THE AFTERNOON WEDNESDAY.
&&
.HYDROLOGY...
ISSUED AT 306 AM EST TUE DEC 4 2012
NO HYDRO ISSUES THIS MORNING QPF LESS THAN A QUARTER INCH IS
EXPECTED FROM SHOWERS ALONG THE COLD FRONT THIS MORNING.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EST WEDNESDAY FOR LMZ844>849.
&&
$$
SYNOPSIS...93
SHORT TERM...93
LONG TERM...OSTUNO
AVIATION...OSTUNO
HYDROLOGY...93
MARINE...93
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
306 AM EST TUE DEC 4 2012
.SYNOPSIS...
ISSUED AT 306 AM EST TUE DEC 4 2012
A BROKEN LINE OF SHOWERS AHEAD OF A COLD FRONT IS MOVING ACROSS
LOWER MICHGIAN EARLY THIS MORNING. THE RAIN WILL MOVE OUT OF THE
AREA BY LATE MORNING. WE/LL SEE SOME SUNSHINE THIS AFTERNOON BUT
TEMPERATURES WILL BE MUCH COOLER THAN YESTERDAY. THERE IS A CHANCE
OF MIXED RAIN AND SNOW FROM THURSDAY THROUGH THE WEEKEND.
TEMPERATURES WILL BE NEAR NORMAL.
&&
.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 306 AM EST TUE DEC 4 2012
FORECAST CONCERNS DEAL PCPN TRENDS THIS MORNING. OVERALL...THE
FORECAST HASN/T CHANGED MUCH.
REGIONAL RADAR SHOWS A BROKEN BAND OF SHOWERS STRETCHING FROM NRN
LAKE HURON SWWD TO NEAR ST LOUIS. THIS PCPN IS ALIGNED ALONG THE
COLD FRONT WHICH IS PUSHING THROUGH THE CWA ATTM. LATEST IR LOOP
SHOWS COOLING CLOUD TOPS OVER ILLINOIS. THIS IS LIKELY IN RESPONSE
TO A WAVE ON THE SRN PORTION OF THE FRONT. HRRR SUGGESTS WE/LL SEE A
LARGER AREA OF PCPN MOVE INTO THE SRN/SE CWA PRIOR TO SUNRISE AS THE
WAVE MOVES NEWD. THIS JUST APPEARS TO BE RAIN...LIGHTNING REMAINS
WELL SW OF THE GREAT LAKES. PCPN WILL END FROM NW TO SE THIS
AFTERNOON AS THE WAVE MOVES MOVES THROUGH.
A SECONDARY COLD FRONT WILL MOVE SEWD THROUGH LOWER MICHIGAN
TONIGHT. WE MAY BRIEFLY SEE A FEW SHSN DEVELOP ALONG THE LAKE SHORE
NORTH OF HOLLAND BUT THEY WON/T AMOUNT TO MUCH AND WILL QUICKLY FADE
BY WEDNESDAY MORNING AS CORE OF THE COLD AIR MOVES EAST. HIGH
PRESSURE WILL SETTLE OVER THE CWA WEDNESDAY.
.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 306 AM EST TUE DEC 4 2012
HALLENGING FORECAST IN THE EXTENDED AS MODEL CONSISTENCY HAS
BEEN POOR THE LAST COUPLE DAYS HANDLING THE DETAILS OF AN INVERTED
TROUGH/SFC WAVE MOVING ALONG THE FRONT STALLED ACROSS THE OHIO
VALLEY...AND A MORE SIGNIFICANT STORM EARLY NEXT WEEK.
WENT WITH LOW CHANCE OR SLIGHT CHANCE POPS EARLY IN THE PERIOD WITH
LOW CONFIDENCE ON DETAILS OF WHEN AND WHERE BEST CHANCES FOR PRECIP
WITH BE. P-TYPE IS ALSO A TOUGH CALL AS THERMAL PROFILES SUGGEST MIX
NORTH AND RAIN SOUTH.
A HIGHER IMPACT EVENT IS EXPECTED NEXT WEEK AS STRONG UPPER TROUGH
MOVES INTO THE ROCKIES WITH SFC LOW FORMING OVER THE PLAINS AND
HEADING FOR LOWER MICHIGAN. AGAIN CONFIDENCE IS LOW ON TIMING DUE TO
MODEL DIFFERENCES AND INCONSISTENCY...BUT A MIXED PRECIP TO RAIN
THEN OVER TO SNOW SCENARIO IS POSSIBLE EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1137 PM EST MON DEC 3 2012
MVFR CIGS / VSBY WITH SHOWERS WILL ACCOMPANY THE COLD FRONT AS IT
MOVES THROUGH THE TAF SITES DURING THE EARLY MORNING HOURS OF
TUESDAY. SO FAR THIS EVENING MOST OF THE RAIN HAS BEEN NORTH OF
I-96. THERE IS ANOTHER SHORTWAVE (SEEN ON WATER VAPOR LOOPS) OVER
KS THIS EVENING. THIS WILL TRAVEL UP THE FRONT TUESDAY AND MAY
PROGLONG THE RAIN OVER JXN/LAN TAF SITES DURING THE MID MORNING
HOURS OF TUESDAY. COLDER DRIER AIR WILL FOLLOW THE FRONT EVEN SO
TUESDAY. THE RESULTS SHOULD BE CLEARING OF THE LOW CLOUDS BY MID
MORNING AND MID CLOUDS BY MID AFTERNOON.
&&
.MARINE...
ISSUED AT 306 AM EST TUE DEC 4 2012
COLD ADVECTION WILL INCREASE WAVE HEIGHTS TODAY INTO WEDNESDAY. WE
EXTENDED THE SCA THROUGH THE AFTERNOON WEDNESDAY.
&&
.HYDROLOGY...
ISSUED AT 306 AM EST TUE DEC 4 2012
NO HYDRO ISSUES THIS MORNING QPF LESS THAN A QUARTER INCH IS
EXPECTED FROM SHOWERS ALONG THE COLD FRONT THIS MORNING.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EST WEDNESDAY FOR LMZ844>849.
&&
$$
SYNOPSIS...93
SHORT TERM...93
LONG TERM...OSTUNO
AVIATION...WDM
HYDROLOGY...93
MARINE...93
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1226 AM EST TUE DEC 4 2012
.SYNOPSIS...
MILD TEMPERATURES WILL CONTINUE AHEAD OF A COLD FRONT...EXPECTED TO
CROSS THE EASTERN CAROLINAS ON WEDNESDAY. SCATTERED SHOWERS WILL
ACCOMPANY THE FRONT. COOLER CONDITIONS ARE EXPECTED AS HIGH PRESSURE
BUILDS OVER THE REGION THURSDAY AND FRIDAY...WITH MODERATING
TEMPERATURES NEXT WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 12:30 AM TUESDAY...AREAS OF FOG...SOME DENSE SPOTS
INCLUDED...NOW FORMING. STILL A GOOD POSSIBILITY THAT WE WILL BE
ISSUING A DENSE FOG ADVISORY EARLY THIS MORNING. PREVIOUS
DISCUSSION FOLLOWS:
THE BROAD CENTER OF 1026 MB HIGH PRESSURE IS LOCATED MAYBE A
HUNDRED MILES OFFSHORE...BUT A ZONE OF VERY WEAK PRESSURE GRADIENT
EXTENDS AS FAR WEST AS GEORGIA. ALTHOUGH SURFACE WINDS ARE VERY
LIGHT OR CALM THERE IS A LITTLE BETTER RETURN FLOW ABOVE THE
SURFACE IN THE 1000-2000 FT AGL LAYER...ABOUT 10-12 KNOTS.
ALTHOUGH NOT AS WIDESPREAD AS LAST NIGHT...SATELLITE IMAGERY
REVEALS AN AREA OF ALTOCUMULUS ALONG THE SOUTH CAROLINA COAST WITH
BASES IN THE 7000-8000 FT RANGE. THIS CLOUD COVER APPEARS TO BE
RELATED TO MOISTURE TRAPPED UNDERNEATH THE SUBSIDENCE INVERSION
ALOFT AND SOME WEAK LIFT ALONG THE UPWARD- SLOPING 295K TO 300K
ISENTROPIC SURFACES. WHILE I WOULD LIKE TO SAY THESE CLOUDS WILL
NOT BE WITH US MUCH LONGER...NAM AND RUC MODELS SHOW CONTINUED
MOISTURE AND WEAK LIFT WHICH MAY SUPPORT SOME CLOUDS ALONG THE
COAST THROUGH DAYBREAK.
THE AMOUNT OF CLOUD COVER IS CRITICALLY IMPORTANT TONIGHT SINCE
BOUNDARY LAYER MOISTURE IS VERY RICH BY DECEMBER STANDARDS...AND
JUST A FEW HOURS OF CLEAR SKIES AND CALM WINDS SHOULD YIELD
WIDESPREAD FOG. MUCH LIKE WE SAW LAST NIGHT THE FOG COULD BECOME
DENSE WITH VISIBILITIES DROPPING BELOW 1/4 MILE AT TIMES. GIVEN
UNCERTAINTIES IN THE TIMING AND LOCATION OF ANY DENSE FOG WE WILL
NOT ISSUE A DENSE FOG ADVISORY AT THIS TIME...BUT ONE MAY BE NEEDED
IN THE NEXT 4-6 HOURS.
VERY LITTLE CHANGES ARE NEEDED TO THE REMAINDER OF THE
FORECAST...WITH LOWS STILL EXPECTED TO FALL INTO THE UPPER 40S TO
AROUND 50.
&&
.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...HIGH PRESSURE ON TUESDAY WILL GIVE WAY TO A
QUICK MOVING FRONT ON WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING.
THE BEST DYNAMICS WILL REMAIN NORTH OF VIRGINIA AND ISENTROPIC
FLOW SHOWS SOME UPWARD VERTICAL MOTION BUT IT IS NOT THAT
IMPRESSIVE IN THE LAYER`S AT BELOW 300 KELVIN. SO EXPECT SCATTERED
SHOWERS WITH LOW QPF VALUES.
MAXIMUM TEMPERATURES ARE EXPECTED TO REMAIN IN THE LOWER TO MID
70S FOR TUESDAY AND UPPER 60S ON WEDNESDAY. LOW TEMPERATURES ARE
EXPECTED TO BE IN THE MID 50S TUESDAY AND WITH THE COLD AIR
ADVECTION BEHIND THE FRONT TEMPERATURES SHOULD DROP INTO THE LOWER
TO MID 40S.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 3 PM MONDAY...MEDIUM RANGE GUIDANCE CONTINUES TO TREND
TOWARD A MILDER AND DRIER SCENARIO FOR THE EXTENDED. INITIALLY A
ZONAL FLOW ALOFT PREVAILS THEN A POTENT SHORTWAVE DIVES INTO THE
EASTERN SLOPES OF THE ROCKIES ALLOWING A SIGNIFICANT RIDGE TO
DEVELOP OFF OF THE SOUTHEAST COAST. CONTINUED TO TREND POPS DOWN
THROUGH THE PERIOD FOLLOWING HPC AS BERMUDA HIGH PRESSURE WILL BE
THE DOMINANT FEATURE FOR OUR AREA. SLIGHT CHANCE POPS REMAIN FOR
MONDAY FOR GENERAL CONVECTION OF ALL THINGS AS SOUNDINGS ARE
SHOWING CAPE VALUES NEAR 500 J/KG. TOUGH TO FIND FORCING OTHER
THAN MESOSCALE FEATURES SUCH AS THE SEA BREEZE AND DIFFERENTIAL
HEATING. SEA FOG REMAINS A POSSIBILITY WITH A QUICK CHECK OF
SURFACE DEWPOINTS IN THE MID TO UPPER 60S SUNDAY...AND RELATIVELY
LIGHT WINDS.
TEMPERATURES WILL BE A BIG STORY AS WELL AS POPS ARE OUT OF THE
FORECAST AND WITH 850MB TEMPERATURES SLIGHTLY WARMER THAN WE HAVE
CURRENTLY...A COUPLE OF DAYS IN THE 70S APPEARS TO BE A GOOD BET.
THESE WILL OCCUR SUNDAY AND MONDAY. LEADING UP TO THIS...MORE
SEASONAL VALUES CAN BE EXPECTED.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AS OF 06Z...EXPECT MVFR/IFR...WITH POSSIBLE LIFR...DUE TO FOG
OVERNIGHT AND INTO TUESDAY MORNING.
NEARLY CLEAR SKIES AND LIGHT WINDS ARE ALLOWING FOR AN IDEAL
RADIATIONAL COOLING CONDITIONS TO ALREADY SET UP ACROSS THE AREA.
LATEST TIME-HEIGHT ANALYSIS AND FCST SOUNDINGS CONTINUE TO DEPICT
THAT SUFFICIENT LOW LEVEL MOISTURE IS SPREAD ACROSS MOST OF THE AREA
DUE TO CONTINUED ONSHORE FLOW. WITH THE ANTICIPATION OF CALM
WINDS...EXPECT IFR TO MVFR DUE TO REDUCED VISIBILITIES TO
CONTINUE. ANTICIPATE CONDITIONS TO DETERIORATE LOWER TO LIFR DUE
TO FOG...WITH THE POTENTIAL FOR LOWERED CIGS AROUND 200FT.
RESTRICTIONS WILL LIKELY PERSIST AFTER DAYBREAK...WITH CONDITIONS
IMPROVING TO VFR BY LATE MORNING AND LASTING THROUGH THE REMAINDER
OF THE VALID PERIOD. EXPECT SOUTHWEST WINDS...BECOMING SOUTH-
SOUTHWEST WITH SUSTAINED WINDS AOB 8 KTS BY THE AFTERNOON
HOURS...BECOMING LIGHT INTO THE EVENING HOURS.
EXTENDED OUTLOOK...A SLIGHT CHANCE OF SHOWERS ON WEDNESDAY
ASSOCIATED WITH A COLD FRONT. OTHERWISE EXPECT VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 12:30 AM TUESDAY...NO CHANGES TO THE FORECAST WITH LATEST
UPDATE. SEAS CONTINUE IN THE 2 FT RANGE...WITH LIGHT AND VARIABLE
WINDS. PREVIOUS DISCUSSION FROM 630 PM FOLLOWS...
LIGHT SOUTH THROUGH WEST WINDS WILL CONTINUE THROUGH THE NIGHT AS
HIGH PRESSURE REMAINS JUST OFFSHORE. SEAS CONSIST ALMOST EXCLUSIVELY
OF A 9 SECOND SOUTHEAST SWELL...AVERAGING 2-3 FT. THE ONLY CHANGE TO
THE FORECAST IS TO RAISE AIR TEMPERATURE FORECASTS BY UP TO 5
DEGREES ACROSS THE OUTER PORTION OF THE COASTAL WATERS WITH THE MILD
SUBTROPICAL AIRMASS. PREVIOUS DISCUSSION FROM 300 PM FOLLOWS...
DESPITE WINDS BEING LESS THAN 10KT TODAY AND EVEN HAVING SOME
VARIABILITY IN DIRECTION THERE IS JUST ENOUGH SWELL ENERGY FOR A 3
FT WAVE OUT AT 41013 AND 41036. WNA AND SWAN SHOW THAT FOR THE MOST
PART THE 3 FT SEAS WILL LARGELY REMAIN OUTSIDE OF THE 20NM FORECAST
ZONES SAVE FOR ALONG FRYING PAN SHOALS..AND EVEN THAT MIGHT BE A
STRETCH. WILL ADVERTISE 2 FT FOR ALL BUT AMZ252 WHERE 2 TO 3 FT WILL
STILL BE ADVERTISED. EVE SHIFT MAY BE ABLE TO DROP 3 FT SEAS AFTER
MONITORING BUOY DATA.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...WINDS WILL BE LIGHT AT 12 UTC ON TUESDAY AND AS
HIGH PRESSURE GIVES AWAY TO FRONTAL BOUNDARY THE WIND DIRECTION WILL
SWING TO THE SOUTHWEST AND INCREASE UP TO 10 KNOTS BY THE END OF THE
DAY. THE WINDS WILL CONTINUE TO VEER FROM THE SOUTHWEST TO NORTHEAST
AS THE FRONT MOVES ACROSS THE COASTAL WATERS. COLD AIR ADVECTION
WILL FOLLOW AND WINDS SPEED ARE EXPECTED TO INCREASE TO 20 TO 25
KNOTS FROM THE NORTHEAST LATE WEDNESDAY NIGHT. A SMALL CRAFT
ADVISORY MAY BE LIKELY IF THE MODELS CONSISTENCY CONTINUES.
LONG TERM /THURSDAY THROUGH FRIDAY/...
AS OF 3 PM MONDAY...NORTHEAST WINDS INITIALLY FROM 15-20 KNOTS AS
HIGH PRESSURE BUILDS DOWN THE EAST COAST. SPEEDS WILL QUICKLY
DIMINISH TO LESS THAN TEN KNOTS BY FRIDAY MORNING. WILL PROBABLY
HAVE A MARGINAL SMALL CRAFT ADVISORY FOR SEAS AS WELL THURSDAY.
WIND SHIFT OCCURS LATE FRIDAY TO SOUTHEAST AS THE AFOREMENTIONED
HIGH QUICKLY MOVES OFFSHORE. SPEEDS WILL REMAIN LIGHT AND CONTINUE
THROUGH SATURDAY. SIGNIFICANT SEAS WILL DROP TO AROUND TWO FEET.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...REK/MBB
SHORT TERM...DRH
LONG TERM...SHK
AVIATION...SGL
MARINE...REK/MBB/SHK/DRH
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
847 PM CST WED DEC 5 2012
.DISCUSSION...
PRECIP CHANCES AND TYPE CONTINUE TO BE THE ISSUES TONIGHT. RADAR
SHOWS SOME ECHOES UP TO 30 DBZ THAT HAVE BEEN MOVING ACROSS THE
NORTHERN CWA...WITH SOME EXTENDING DOWN INTO THE JMS AREA DURING
THE LAST FEW HOURS. RAP AND NAM MODEL SOUNDINGS FOR THIS EVENING
CONTINUE TO SHOW A FAIRLY STRONG WARM LAYER ALOFT...SO FZRA
CONTINUES TO BE A POSSIBILITY FOR THE SITES THAT HAVE SFC OBS
BELOW FREEZING. ON THE OTHER HAND...THE MODEL SOUNDINGS ALSO SHOW
QUITE A BIT OF DRY AIR BELOW 700MB OR SO. THERE HAS BEEN SOME UP
REPORTED AT AWOS STATIONS IN THE NORTHERN TIER...BUT SPOTTERS DID
NOT HAVE MUCH AND WEB CAMS SHOW FAIRLY DRY PAVEMENT. GIVEN THE DRY
AIR AND FAST MOVEMENT OF THE ECHOES...THINK THAT SPRINKLES ARE THE
MOSTLY LIKELY FORM OF PRECIP THIS EVENING...EITHER FREEZING OR
NOT. AT THIS POINT DO NOT SEE ANY REASON TO DEVIATE FROM THE 20-30
POPS WE HAVE GOING...WITH SOME MINOR TWEAKS FOR CURRENT SFC OBS.
MODEL SOUNDINGS GO BELOW FREEZING COMPLETELY IN THE NORTHEAST
AFTER MIDNIGHT...SO INCLUDED A SNOW MENTION IN THAT AREA BUT AGAIN
POPS WILL BE PRETTY LOW. KEPT RAIN/FREEZING RAIN IN THE
SOUTHEASTERN COUNTIES. TEMPS WILL NOT DROP MUCH UNTIL EARLY
MORNING AT LEAST IN THE SOUTHERN COUNTIES AS WARM AIR ADVECTION
CONTINUES IN THE SOUTH TO SOUTHWESTERLY WINDS AHEAD OF THE COLD
FRONT COMING THROUGH. KEPT SOME PRETTY COLD TEMPS BELOW 20 IN THE
NORTHWEST BUT THEY WILL HAVE THE FRONT COMING THROUGH EARLIER AND
MAY EVEN SEE SOME BREAKS IN THE CLOUDS.
&&
.AVIATION...
VFR CONDITIONS WILL CONTINUE FOR MUCH OF THE OVERNIGHT AS SAT LOOP
HAS THE LOW STRATUS ALL ON THE BACK SIDE OF THE COLD FRONT. FAIRLY
BREEZY SOUTHERLY WINDS WILL CONTINUE FOR THE NEXT FEW HOURS BEFORE
DECREASING A BIT AND SHIFTING TO THE SOUTHWEST AS A SFC TROUGH
AXIS COMES OUT. THE MAIN COLD FRONT WILL SHIFT WINDS TO THE
NORTHWEST AND PICK UP AGAIN...AFTER MIDNIGHT AROUND KDVL AND BY
12Z IN THE EASTERN TAF SITES. SOME MVFR STRATUS IS POSSIBLE
TOMORROW MORNING BEHIND THE BOUNDARY...WITH THE BEST CHANCES FOR
REDUCED CEILINGS AT THE NORTHERN TAF SITES.
&&
.PREV DISCUSSION... /ISSUED 320 PM CST WED DEC 5 2012/
SHORT TERM...TONIGHT THROUGH SATURDAY
CHALLENGES INCLUDE PRECIPITATION CHANCES TONIGHT AND ALSO FRIDAY
INTO SATURDAY AND TEMPERATURES THROUGH THE PERIOD. MODELS ARE IN
GOOD AGREEMENT THROUGH 12 UTC FRIDAY...DIVERGING THEREAFTER FOR
THE WEEKEND SYSTEM. WILL USE A BLENDED SOLUTION FOR THIS FORECAST
PACKAGE.
FOR TONIGHT...A COLD FRONT WILL SWEEP ACROSS THE FORECAST AREA.
SOME LIGHT FREEZING RAIN IS POSSIBLE AHEAD OF THE FRONT GIVEN WARM
MID-LEVELS AND SUB-FREEZING SURFACE TEMPERATURES. PRIMARY LIFT AND
MOISTURE IS AT OR ABOVE 700 HPA...SO NOT EXPECTING MUCH IN THE WAY
OF ACCUMULATION. DID EXPAND 20 POPS TO THE SOUTH AND WEST THIS
EVENING ALONG FRONTAL BOUNDARY...BUT BEST CHANCE OF PRECIPITATION
WILL BE CLOSER TO THE CANADIAN BORDER GIVEN GREATER UPPER LEVEL
SUPPORT FROM 300 HPA JET STREAK. IF SURFACE TEMPERATURES REMAIN
ABOVE FREEZING...EXPECT ALL RAIN. AFTER MIDNIGHT...DECREASING
TEMPERATURES MAY RESULT IN A RAIN/FREEZING RAIN OR SNOW/FREEZING
RAIN MIX. CLOUD COVER AND ELEVATED WIND WILL KEEP TEMPERATURES
FROM FALLING TOO FAR WITH THURSDAY MORNING LOWS IN THE 20S.
THURSDAY WILL BE DRY AS A SURFACE RIDGE BEGINS TO BUILD ACROSS
THE WESTERN DAKOTAS. SHOULD SEE SOME BREAKS IN THE CLOUDS...BUT
NORTHWEST WIND WILL BE BREEZY AT TIMES...GUSTING TO 20 MPH IN THE
AFTERNOON. TEMPERATURES WILL BE SIMILAR TO OR SLIGHTLY COOLER THAN
TODAY...WITH HIGHS FROM THE MID 20S TO MID 30S.
WILL KEEP SLIGHT CHANCE POPS FRIDAY ACROSS THE SOUTH ASSOCIATED
WITH THE NEXT WEAK WAVE ROUNDING THE BASE OF THE LARGE BROAD TROUGH
ALOFT. MODEL QPF IS HIGHEST ACROSS EASTERN SD INTO SOUTHWEST MN...
SO THINK ANY ACCUMULATION SHOULD BE MINIMAL. THERMAL GRADIENT WILL
BISECT THE FORECAST AREA FROM NORTH TO SOUTH...SO EXPECT
TEMPERATURES TO RANGE FROM THE MID TEENS ALONG THE CANADIAN BORDER
TO NEAR 30 DEGREES ACROSS THE SOUTHERN VALLEY.
PRECIPITATION CHANCES INCREASE LATE FRIDAY NIGHT INTO SATURDAY
DEPENDING ON MODEL. GFS/ECMWF BOTH PROPAGATE A STRONGER SHORT-WAVE
INTO THE WESTERN DAKOTAS BY 00 UTC SUNDAY. HOWEVER...STRENGTH AND
POSITION OF SURFACE HIGH DICTATE PRECIPITATION PLACEMENT. THE GFS
PAINTS MAJORITY OF QPF TO THE SOUTH...WHEREAS THE ECMWF PLACES A
LARGE SWATH OF PRECIPITATION ACROSS THE FORECAST AREA. CONSIDERABLE
UNCERTAINTY PRECLUDES A MORE THOROUGH ANALYSIS...SO FOR NOW...WILL
KEEP POPS IN THE 20 TO 30 PERCENT RANGE ALONG AND WEST OF THE
VALLEY. TEMPERATURES SHOULD BE COLD ENOUGH FOR ALL SNOW...ALTHOUGH
EXACT VALUES WILL BE DEPENDENT ON SURFACE LOW TRACK. STAY TUNED.
LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY
MODELS ARE IN GOOD AGREEMENT SHOWING A FAIRLY STABLE PATTERN
THROUGH THE PERIOD...WITH A BROAD TROUGH ACROSS THE CONUS. THE
MAIN MODEL DIFFERENCES COME WITH STRENGTH/TIMING OF INDIVIDUAL
SHORTWAVES WITHIN THIS FLOW. THE BEST CHANCE FOR MEASURABLE SNOW
APPEARS TO BE SAT NIGHT AND SUNDAY. THE GFS IS WEAKEST AND
FURTHEST SOUTH...WITH THE GEM AND ECMWF STRONGER AND NORTH.
TEMPERATURES WILL BE NEAR...OR SLIGHTLY BELOW NORMAL.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
JR
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1020 PM EST WED DEC 5 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 THURSDAY/...
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 /THURSDAY NIGHT 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 /04Z THURSDAY THROUGH MONDAY/...
AT KCLT...PRECIP HAS TAPERED OFF AT THE TERMINAL AS THE FRONT
CONTINUES TO SINK SOUTH. NE WINDS HAVE DEVELOPED BEHIND THE FRONT
AND IT WILL CONTINUE THROUGH THE TAF PERIOD. WEAK ISENTROPIC LIFT
ASSOCIATED WITH COLD AIR DAMMING WILL RESULT IN MOSTLY CLOUDY SKIES
WITH CEILINGS AROUND 5K THROUGH TONIGHT BEFORE DROPPING TO 3K FT IN
MVFR CEILING BY 12Z THU.
ELSEWHERE...SCATTERED SHOWERS HAVE DEVELOPED ACROSS PORTIONS OF SC
UPSTATE THIS EVENING AND WILL AFFECT KGSP AND KGMU THROUGH 1Z THU.
OTHERWISE...EXPECT MOSTLY CLOUDY SKIES IN VFR CEILING 4-5K FT
THROUGH TONIGHT. WEAK ISENTROPIC LIFT ASSOCIATED WITH COLD AIR
DAMMING WILL PRODUCE CLOUDS IN MVFR CEILING 2500-3000 FT OVER SC
PIEDMONT BY 12Z THU AND WILL PERSIST THROUGH 00Z FRI. NE WINDS WILL
CONTINUE ACROSS THE REGION EXCEPT KAVL WHERE NE WINDS WILL BECOME
SOUTHERLY BY 9Z THU.
OUTLOOK... WIDELY SCATTERED SHOWERS WITH CEILING AND VISIBILITY
RESTRICTIONS POSSIBLE OVER THE MOUNTAINS FRIDAY AND SATURDAY.
STRATUS AND FOG COULD OCCUR BOTH DAYS DUE TO WEAKENING COLD AIR
DAMMING. COLD FRONT CROSSING THE AREA MONDAY WILL PRODUCE SCATTERED
SHOWERS.
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...JOH/LGL
SHORT TERM...CSH
LONG TERM...ARK
AVIATION...JOH
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
747 PM EST WED DEC 5 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 THURSDAY/...
AS OF 630 PM UPDATE...SCATTERED SHOWERS HAVE DEVELOPED ACROSS
PORTIONS OF UPSTATE SC WHILE PRECIP TAPERED OFF ELSEWHERE THIS
EVENING. THESE SHOWERS WILL NOT LAST LONG AS ATMOS BEHIND THE FRONT
STABILIZES THROUGH OVERNIGHT HOURS.
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 /THURSDAY NIGHT 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 /01Z THURSDAY THROUGH MONDAY/...
AT KCLT...PRECIP HAS TAPERED OFF AT THE TERMINAL AS THE FRONT
CONTINUES TO SINK SOUTH. NE WINDS HAVE DEVELOPED BEHIND THE FRONT
AND IT WILL CONTINUE THROUGH THE TAF PERIOD. WEAK ISENTROPIC LIFT
ASSOCIATED WITH COLD AIR DAMMING WILL RESULT IN MOSTLY CLOUDY SKIES
WITH CEILINGS AROUND 5K THROUGH TONIGHT BEFORE DROPPING TO 3K FT IN
MVFR CEILING BY 12Z THU.
ELSEWHERE...SCATTERED SHOWERS HAVE DEVELOPED ACROSS PORTIONS OF SC
UPSTATE THIS EVENING AND WILL AFFECT KGSP AND KGMU THROUGH 1Z THU.
OTHERWISE...EXPECT MOSTLY CLOUDY SKIES IN VFR CEILING 4-5K FT
THROUGH TONIGHT. WEAK ISENTROPIC LIFT ASSOCIATED WITH COLD AIR
DAMMING WILL PRODUCE CLOUDS IN MVFR CEILING 2500-3000 FT OVER SC
PIEDMONT BY 12Z THU AND WILL PERSIST THROUGH 00Z FRI. NE WINDS WILL
CONTINUE ACROSS THE REGION EXCEPT KAVL WHERE NE WINDS WILL BECOME
SOUTHERLY BY 9Z THU.
OUTLOOK... WIDELY SCATTERED SHOWERS WITH CEILING AND VISIBILITY
RESTRICTIONS POSSIBLE OVER THE MOUNTAINS FRIDAY AND SATURDAY.
STRATUS AND FOG COULD OCCUR BOTH DAYS DUE TO WEAKENING COLD AIR
DAMMING. COLD FRONT CROSSING THE AREA MONDAY WILL PRODUCE SCATTERED
SHOWERS.
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...JOH/LGL
SHORT TERM...CSH
LONG TERM...ARK
AVIATION...JOH
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
739 PM EST WED DEC 5 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 THURSDAY/...
AS OF 630 PM UPDATE...SCATTERED SHOWERS HAVE DEVELOPED ACROSS
PORTIONS OF UPSTATE SC WHILE PRECIP TAPERED OFF ELSEWHERE THIS
EVENING. THESE SHOWERS WILL NOT LAST LONG AS ATMOS BEHIND THE FRONT
STABILIZES THROUGH OVERNIGHT HOURS.
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 /THURSDAY NIGHT 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 /01Z THURSDAY THROUGH MONDAY/...
AT KCLT...PRECIP HAS TAPERED OFF AT THE TERMINAL AS THE FRONT
CONTINUES TO SINK SOUTH. NE WINDS HAVE DEVELOPED BEHIND THE FRONT
AND IT WILL CONTINUE THROUGH THE TAF PERIOD. WEAK ISENTROPIC LIFT
ASSOCIATED WITH COLD AIR DAMMING WILL RESULT IN MOSTLY CLOUDY SKIES
WITH CEILINGS AROUND 5K THROUGH TONIGHT BEFORE DROPPING TO 3K FT IN
MVFR CEILING BY 12Z THU.
ELSEWHERE...SCATTERED SHOWERS HAVE DEVELOPED ACROSS PORTIONS OF SC
UPSTATE THIS EVENING AND WILL AFFECT KGSP AND KGMU THROUGH 1Z THU.
OTHERWISE...EXPECT MOSTLY CLOUDY SKIES IN VFR CEILING 4-5K FT
THROUGH TONIGHT. WEAK ISENTROPIC LIFT ASSOCIATED WITH COLD AIR
DAMMING WILL PRODUCE CLOUDS IN MVFR CEILING 2500-3000 FT OVER SC
PIEDMONT BY 12Z THU. KAVL AND KHKY WILL REMAIN CLOUDY WITH CEILINGS
4-5K FT THROUGH THE PERIOD. NE WINDS WILL CONTINUE FOR ALL TAF SITES
THROUGH 00Z FRI.
OUTLOOK... WIDELY SCATTERED SHOWERS WITH CEILING AND VISIBILITY
RESTRICTIONS POSSIBLE OVER THE MOUNTAINS FRIDAY AND SATURDAY.
STRATUS AND FOG COULD OCCUR BOTH DAYS DUE TO WEAKENING COLD AIR
DAMMING. COLD FRONT CROSSING THE AREA MONDAY WILL PRODUCE SCATTERED
SHOWERS.
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...JOH/LGL
SHORT TERM...CSH
LONG TERM...ARK
AVIATION...JOH
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
ISSUED BY NATIONAL WEATHER SERVICE NORTH PLATTE NE
1042 AM MST TUE DEC 4 2012
&&
.AVIATION...
VFR CONDITIONS EXPECTED THROUGH THE 18Z TAF FORECAST
CYCLE. HOWEVER...GUSTY SOUTHWEST /210-240/ SFC WINDS WILL CONTINUE
AT KGCC WITH GUST POTENTIAL AT OR ABOVE 20KTS THIS AFTERNOON. MODEL
GUIDANCE INDICATES A BRIEF PERIOD OF LIGHTER WINDS AT KGCC THIS
EVENING...BUT INCREASE ONCE AGAIN OVERNIGHT WITH 15KTS OR GREATER
AT THE TERMINAL. AT KRAP...LESSER WINDS EXPECTED....WITH
SOUTHERLY PEAK GUST POTENTIAL AT OR SLIGHTLY ABOVE 15 KTS THIS
AFTERNOON...THEN LIGHT AND VARIABLE OVERNIGHT.
&&
.UPDATE...MADE SOME MINOR CHANGES TO THE ONGOING FCST...MAINLY TO
DELAY THE ONSET OF CLOUDINESS THIS AFTERNOON BASED ON UPSTREAM
SATELLITE IMAGERY. BASED ON THE 12Z UNR RAOB AND MIXED H85 TEMPS...HIGHS
THIS AFTERNOON SHOULD BE AROUND 50 FOR RAPID CITY. H85 TEMPS IN THE
LATEST RUC AND NAM SOLNS INCREASE AROUND A DEGREE OR TWO THIS
AFTERNOON...SO HIGHS IN THE LOWER 50S SEEM PLAUSIBLE FOR RAPID CITY.
WITH HIGH CLOUDINESS HOLDING OFF UNTIL THE MID AFTERNOON HOURS...ITS
EFFECTS ON HIGHS ARE EXPECTED TO BE NEGLIGIBLE SO MIXED TEMPS WILL BE
UTILIZED IN THE FCST. WINDS THIS AFTERNOON WILL SHIFT TO THE SOUTH
AS HIGH PRESSURE BUILDS INTO EASTERN NORTH DAKOTA AND NORTHWESTERN
MN.
PREV DISCUSSION... /ISSUED 316 AM MST MON DEC 3 2012/
DISCUSSION...CURRENT SURFACE ANALYSIS SHOWS HIGH PRESSURE OVER THE
CENTRAL ROCKIES. LOW PRESSURE IS OVER SOUTHWESTERN ONTARIO...WITH A
COLD FRONT STRETCHING ACROSS NORTHERN MN...ND...AND NORTHEASTERN MT.
UPPER LEVEL ANALYSIS SHOWS WEAK RIDGING OVER THE NORTHERN
ROCKIES...WITH LOW REMAINING OFF THE PACIFIC NW COAST. SKIES ARE
MOSTLY CLEAR ACROSS THE AREA WITH TEMPS IN THE MID 20S TO MID 30S.
WINDS ARE LIGHT FROM THE WEST TO SOUTHWEST.
MILD AND DRY CONDITIONS WILL CONTINUE THROUGH WEDNESDAY...WITH
HIGHS 20 TO 25 DEGREES ABOVE AVERAGE ON WEDNESDAY. A COLD FRONT
WILL MOVE THROUGH THE AREA WEDNESDAY NIGHT...BRINGING TEMPS BACK
TO MORE NORMAL LEVELS FOR THE END OF THE WEEK. A BROAD UPPER TROF
WILL THEN SLOWLY SETTLE OVER THE AREA LATE IN THE WEEK..,BRINGING
UNSETTLED WEATHER THROUGH THE WEEKEND AND KEEPING TEMPS ON THE
COLD SIDE.
FOR TODAY...SKIES WILL START OFF MAINLY SUNNY...WITH INCREASING
MID AND HIGH CLOUDINESS FROM WEST TO EAST DURING THE DAY. THE WEAK
COLD FRONT TO THE NORTH WILL SINK SLOWLY SOUTH AND WEST DURING THE
DAY...STALLING OUT ALONG OR JUST EAST OF THE BLACK HILLS BY LATE
TODAY. HIGHS WILL RANGE FROM THE MID 40S OVER THE HIGHER BLACK
HILLS AND THE LEMMON AREA...TO THE MID 50S OVER MUCH OF
SOUTHWESTERN AND SOUTH CENTRAL SD. SOUTHWESTERLY WINDS WILL
INCREASE ACROSS NORTHEASTERN WY AND PORTIONS OF THE BLACK
HILLS...BECOMING BREEZY AT TIMES ACROSS CAMPBELL CO...ESPECIALLY
SOUTHERN CAMPBELL CO. EAST OF THE BLACK HILLS...WINDS WILL SWITCH
OVER TO THE SOUTHEAST DURING THE AFTERNOON. SKIES WILL BE PARTLY
CLOUDY IN GENERAL TONIGHT WITH LOWS MOSTLY IN THE 30S. WINDS WILL
REMAIN BREEZY AT TIMES ACROSS PORTIONS OF NORTHEASTERN WY AND THE
BLACK HILLS.
WEAK RIDGE TO THE WEST WILL PASS OVER THE AREA LATE TONIGHT AND
WEDNESDAY MORNING AS FRONTAL BOUNDARY PUSHES OFF TO THE EAST AS A
WARM FRONT. WEDNESDAY WILL BE THE MILDEST DAY OF THE WEEK...WITH
HIGHS MOSTLY IN THE UPPER 50S AND LOWER 60S. WINDS WILL BE
VARIABLE AS A WEAK SURFACE LOW DEVELOPS AND MOVES OVER THE AREA.
THE NEXT COLD FRONT WILL PASS THROUGH THE AREA WEDNESDAY NIGHT.
UPPER LEVEL ENERGY ACCOMPANYING THE FRONT LOOKS TO BE RELATIVELY
WEAK...BUT ISOLATED TO SCATTERED SHOWERS ARE EXPECTED
OVERNIGHT...MOSTLY IN THE FORM OF RAIN...AS COLDER AIR IS SLOW TO
PUSH IN BEHIND THE FRONT. LOWS WILL MOSTLY BE IN THE 30S.
THURSDAY LOOKS TO BE MAINLY CLOUDY AND COOL...WITH TEMPS NOT
RISING MUCH. WILL GO WITH HIGHS IN THE MID 30S TO MID 40S FOR NOW.
WEAK SHORTWAVE ENERGY PASSING ACROSS THE AREA WILL BRING A
CONTINUED CHANCE FOR MOSTLY LIGHT RAIN AND SNOW SHOWERS. A
STRONGER WAVE IS PROGGED TO PASS OVER THE AREA THURSDAY NIGHT INTO
FRIDAY. THIS ONE HAS THE POTENTIAL TO BRING AT LEAST A LIGHT
ACCUMULATION OF SNOW TO A GOOD PORTION OF THE AREA. VARIOUS MEDIUM
RANGE MODELS STILL DIFFER ON TIMING AND TRACK OF WAVE...AND WHERE
BETTER SNOW POTENTIAL WILL BE...SO WILL GO WITH CHANCE POPS FOR
NOW ACROSS MUCH OF THE CWA.
EXTENDED...THE MEDIUM RANGE MODELS CONTINUE TO SHOW A MAJOR CHANGE
TO COLD UNSETTLED WEATHER FROM THE END OF THE WEEK THROUGH THE
WEEKEND. A BROAD TROUGH DEVELOPING OVER THE NORTH CENTRAL U.S. WILL
OPEN THE WAY FOR ARCTIC AIR TO POUR INTO THE NORTHERN PLAINS. THE
JET STREAM WILL ALSO DROP INTO THE CENTRAL PLAINS ALLOWING ANOTHER
COLD FRONT TO CROSS THE REGION ON FRIDAY...AND CARRY ADDITIONAL
UPPER LEVEL SYSTEMS THROUGH THE DAKOTAS SATURDAY AND SUNDAY. A BRIEF
WARMING TREND IS EXPECTED FOR THE FIRST COUPLE OF DAYS NEXT WEEK
AFTER THE COLD AIRMASS MOVES EAST.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
SHORT TERM...WFO UNR/LBF
LONG TERM....WFO UNR/LBF
AVIATION...JACOBS
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
ISSUED BY THE NATIONAL WEATHER SERVICE NORTH PLATTE NE
1010 AM CST TUE DEC 4 2012
.UPDATE...MADE SOME MINOR CHANGES TO THE ONGOING FCST...MAINLY TO
DELAY THE ONSET OF CLOUDINESS THIS AFTERNOON BASED ON UPSTREAM
SATELLITE IMAGERY. BASED ON THE 12Z UNR RAOB AND MIXED H85 TEMPS...HIGHS
THIS AFTERNOON SHOULD BE AROUND 50 FOR RAPID CITY. H85 TEMPS IN THE
LATEST RUC AND NAM SOLNS INCREASE AROUND A DEGREE OR TWO THIS
AFTERNOON...SO HIGHS IN THE LOWER 50S SEEM PLAUSIBLE FOR RAPID CITY.
WITH HIGH CLOUDINESS HOLDING OFF UNTIL THE MID AFTERNOON HOURS...ITS
EFFECTS ON HIGHS ARE EXPECTED TO BE NEGLIGIBLE SO MIXED TEMPS WILL BE
UTILIZED IN THE FCST. WINDS THIS AFTERNOON WILL SHIFT TO THE SOUTH
AS HIGH PRESSURE BUILDS INTO EASTERN NORTH DAKOTA AND NORTHWESTERN
MN.
.AVIATION UPDATE...FOR THE 18Z TAFS...VFR FLT CONDS ARE EXPECTED
OVER THE NEXT 24 HRS.
&&
.PREV DISCUSSION... /ISSUED 316 AM MST MON DEC 3 2012/
DISCUSSION...CURRENT SURFACE ANALYSIS SHOWS HIGH PRESSURE OVER THE
CENTRAL ROCKIES. LOW PRESSURE IS OVER SOUTHWESTERN ONTARIO...WITH A
COLD FRONT STRETCHING ACROSS NORTHERN MN...ND...AND NORTHEASTERN MT.
UPPER LEVEL ANALYSIS SHOWS WEAK RIDGING OVER THE NORTHERN
ROCKIES...WITH LOW REMAINING OFF THE PACIFIC NW COAST. SKIES ARE
MOSTLY CLEAR ACROSS THE AREA WITH TEMPS IN THE MID 20S TO MID 30S.
WINDS ARE LIGHT FROM THE WEST TO SOUTHWEST.
MILD AND DRY CONDITIONS WILL CONTINUE THROUGH WEDNESDAY...WITH
HIGHS 20 TO 25 DEGREES ABOVE AVERAGE ON WEDNESDAY. A COLD FRONT
WILL MOVE THROUGH THE AREA WEDNESDAY NIGHT...BRINGING TEMPS BACK
TO MORE NORMAL LEVELS FOR THE END OF THE WEEK. A BROAD UPPER TROF
WILL THEN SLOWLY SETTLE OVER THE AREA LATE IN THE WEEK..,BRINGING
UNSETTLED WEATHER THROUGH THE WEEKEND AND KEEPING TEMPS ON THE
COLD SIDE.
FOR TODAY...SKIES WILL START OFF MAINLY SUNNY...WITH INCREASING
MID AND HIGH CLOUDINESS FROM WEST TO EAST DURING THE DAY. THE WEAK
COLD FRONT TO THE NORTH WILL SINK SLOWLY SOUTH AND WEST DURING THE
DAY...STALLING OUT ALONG OR JUST EAST OF THE BLACK HILLS BY LATE
TODAY. HIGHS WILL RANGE FROM THE MID 40S OVER THE HIGHER BLACK
HILLS AND THE LEMMON AREA...TO THE MID 50S OVER MUCH OF
SOUTHWESTERN AND SOUTH CENTRAL SD. SOUTHWESTERLY WINDS WILL
INCREASE ACROSS NORTHEASTERN WY AND PORTIONS OF THE BLACK
HILLS...BECOMING BREEZY AT TIMES ACROSS CAMPBELL CO...ESPECIALLY
SOUTHERN CAMPBELL CO. EAST OF THE BLACK HILLS...WINDS WILL SWITCH
OVER TO THE SOUTHEAST DURING THE AFTERNOON. SKIES WILL BE PARTLY
CLOUDY IN GENERAL TONIGHT WITH LOWS MOSTLY IN THE 30S. WINDS WILL
REMAIN BREEZY AT TIMES ACROSS PORTIONS OF NORTHEASTERN WY AND THE
BLACK HILLS.
WEAK RIDGE TO THE WEST WILL PASS OVER THE AREA LATE TONIGHT AND
WEDNESDAY MORNING AS FRONTAL BOUNDARY PUSHES OFF TO THE EAST AS A
WARM FRONT. WEDNESDAY WILL BE THE MILDEST DAY OF THE WEEK...WITH
HIGHS MOSTLY IN THE UPPER 50S AND LOWER 60S. WINDS WILL BE
VARIABLE AS A WEAK SURFACE LOW DEVELOPS AND MOVES OVER THE AREA.
THE NEXT COLD FRONT WILL PASS THROUGH THE AREA WEDNESDAY NIGHT.
UPPER LEVEL ENERGY ACCOMPANYING THE FRONT LOOKS TO BE RELATIVELY
WEAK...BUT ISOLATED TO SCATTERED SHOWERS ARE EXPECTED
OVERNIGHT...MOSTLY IN THE FORM OF RAIN...AS COLDER AIR IS SLOW TO
PUSH IN BEHIND THE FRONT. LOWS WILL MOSTLY BE IN THE 30S.
THURSDAY LOOKS TO BE MAINLY CLOUDY AND COOL...WITH TEMPS NOT
RISING MUCH. WILL GO WITH HIGHS IN THE MID 30S TO MID 40S FOR NOW.
WEAK SHORTWAVE ENERGY PASSING ACROSS THE AREA WILL BRING A
CONTINUED CHANCE FOR MOSTLY LIGHT RAIN AND SNOW SHOWERS. A
STRONGER WAVE IS PROGGED TO PASS OVER THE AREA THURSDAY NIGHT INTO
FRIDAY. THIS ONE HAS THE POTENTIAL TO BRING AT LEAST A LIGHT
ACCUMULATION OF SNOW TO A GOOD PORTION OF THE AREA. VARIOUS MEDIUM
RANGE MODELS STILL DIFFER ON TIMING AND TRACK OF WAVE...AND WHERE
BETTER SNOW POTENTIAL WILL BE...SO WILL GO WITH CHANCE POPS FOR
NOW ACROSS MUCH OF THE CWA.
EXTENDED...THE MEDIUM RANGE MODELS CONTINUE TO SHOW A MAJOR CHANGE
TO COLD UNSETTLED WEATHER FROM THE END OF THE WEEK THROUGH THE
WEEKEND. A BROAD TROUGH DEVELOPING OVER THE NORTH CENTRAL U.S. WILL
OPEN THE WAY FOR ARCTIC AIR TO POUR INTO THE NORTHERN PLAINS. THE
JET STREAM WILL ALSO DROP INTO THE CENTRAL PLAINS ALLOWING ANOTHER
COLD FRONT TO CROSS THE REGION ON FRIDAY...AND CARRY ADDITIONAL
UPPER LEVEL SYSTEMS THROUGH THE DAKOTAS SATURDAY AND SUNDAY. A BRIEF
WARMING TREND IS EXPECTED FOR THE FIRST COUPLE OF DAYS NEXT WEEK
AFTER THE COLD AIRMASS MOVES EAST.
&&
.AVIATION...12Z TAFS
VFR CONDITIONS EXPECTED THROUGH THIS AFTERNOON.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
SHORT TERM...26
LONG TERM....CARPENTER
AVIATION...CARPENTER
UPDATE...NWS LBF
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1037 AM PST Tue Dec 4 2012
.SYNOPSIS...
A strong and moist storm system will deliver widespread valley
rain and mountain snow to all areas today. The snow could be locally
heavy near the north Cascades and over the highest mountains
elsewhere. The remainder of the week will be cooler and
showery...with a series of weak weather disturbances moving
through the Inland Northwest.
&&
.DISCUSSION...
A tricky update tot he forecast this morning as precipitation
looks to redevelop over the southeastern portion of the region,
but dry over the extreme northwest portion of the region. The
tricky part is forecasting where this line of wet versus dry will
actually set up. The HRRR model is doing the best with where we
are currently seeing precipitation this morning. This guidance is
suggesting that precipitation will become more widespread after
noon today. Precipitation looks to remain east of a line from
Moses Lake to Omak and up along the Cascade crest. Best chances
will be across extreme eastern Washington and into the Idaho
Panhandle. This precipitation will continue through tonight and
taper off by Wednesday morning.
Snow levels are expect to rise up around 5500 feet around Stevens
Pass to around 4000 feet near the Canadian border this afternoon.
This will result in rain for Stevens Pass. Loup Loup Pass may see
a mix of some light rain and snow, but Blewett Pass will remain
dry or see some light rainfall this afternoon as well. Web cams
show all these passes transitioning from being snow covered to
just wet pavement. Seeing that we will continue with strong
westerly flow and much of the moisture remaining south of the
area, we will go ahead and cancel the Winter Weather Advisory for
the Cascades with this forecast update. /SVH
&&
.AVIATION...
18Z TAFS: Rain and mountain snow across the region has tapered off
a bit this morning as drier air aloft moved across the region.
However, another slug of moisture is beginning to ride up into the
region from the southwest. This will result in precipitaiton
becoming more widespread this afternoon into tonight. Rainfall is
expected at KGEG, KSFF, KCOE, KPUW and KLWS through early
Wednesday morning; KMWH will be on the western fringe of this
moisture. Low level moisture will keep cigs down through tonight
with IFR/MVFR conditions expected to continue at most terminals.
Winds are expected to become a little breezy overnight as low
levels become a bit more unstable. This should begin to break up
the stratus Wednesday morning as drier air aloft is mixed down
toward the surface. /SVH
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 45 39 41 28 35 26 / 60 80 10 10 60 70
Coeur d`Alene 45 39 40 28 35 25 / 70 90 40 10 70 80
Pullman 46 40 42 29 37 28 / 90 90 40 10 50 60
Lewiston 52 45 48 33 45 31 / 60 90 30 10 30 60
Colville 44 41 41 30 36 25 / 30 80 20 30 70 70
Sandpoint 42 39 39 28 34 25 / 70 90 50 30 80 90
Kellogg 42 37 37 30 33 25 / 100 100 50 20 80 90
Moses Lake 49 40 45 26 37 25 / 20 20 0 10 10 20
Wenatchee 45 37 44 27 38 26 / 20 20 0 10 40 20
Omak 43 36 40 25 35 21 / 20 20 10 10 40 20
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
728 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...TONIGHT AND THURSDAY
537 PM CST WED DEC 5 2012
SOUTHEAST WINDS HAVE INCREASED THIS AFTERNOON IN BETWEEN HIGH
PRESSURE OVER MICHIGAN AND A COLD FRONT OVER CENTRAL SOUTH DAKOTA.
THESE WINDS LOOK TO INCREASE DRAMATICALLY TONIGHT...PARTICULARLY
ALOFT...WITH SOUTHWEST SPEEDS OF 50-55 KT AT 2000 FT AT BOTH TAF
SITES BY 04Z. MEANWHILE...AT THE SURFACE...SOUTH TO SOUTHEAST
WINDS OF 10-20 KT WITH SLIGHTLY HIGHER GUSTS CONTINUE...STRONGEST
AT KRST. THE WINDS WILL ALSO MAINTAIN A FEED OF DRY AIR IN AT THE
LOW LEVELS OF THE TROPOSPHERE FOR MUCH OF THE NIGHT...ALLOWING VFR
CONDITIONS TO PERSIST. AROUND 12Z...THE COLD FRONT SHOULD BE
APPROACHING MINNEAPOLIS AND ALBERTA LEA. AHEAD OF THE FRONT...A
BAND OF RAIN LOOKS TO DEVELOP IN THE 09-12Z TIME PERIOD...SHIFTING
EAST INTO KRST AROUND 13Z AND KLSE AROUND 15Z. HAVE LOWERED
CEILINGS A LITTLE FROM THE PREVIOUS FORECAST...BUT VFR CONDITIONS
STILL APPEAR TO BE THE RULE. 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.
&&
.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 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.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS BISMARCK ND
111 AM CST THU DEC 6 2012
.DISCUSSION...
SECONDARY COLD FRONT ADVECTING FROM NORTH TO SOUTH ACROSS NORTH
DAKOTA EARLY THIS THURSDAY MORNING. STRONG PRESSURE RISES ACROSS
THE NORTH HAS RESULTING IN WIND GUSTS UP TO 35KTS AT VARIOUS
OBSERVING SITES ACROSS THE NORTHWEST AND NORTH CENTRAL THE PAST
FEW HOURS. COULD BE EVEN STRONGER IF THE CENTER OF THE PRESSURE
RISE BUBBLE WAS FARTHER SOUTH...WITH BRANDON MANITOBA REPORTING A
WIND GUST OF 42KTS THE PAST HOUR. EXPECT THE WINDS TO TAPER OFF AS
THE PRESSURE RISE BUBBLE ADVECTS FARTHER TO THE EAST. WITH THE
INCREASE IN WINDS TEMPERATURES HAVE JUMPED SEVERAL DEGREES...BUT
DO COOL AS THE WINDS SLOWLY DECREASE. OVERALL WILL MAINTAIN
FORECAST LOWS PRETTY MUCH AS WAS INHERITED...WITH THE MAIN UPDATE
REGARDING TEMPERATURES ADJUSTING THE HOURLY TREND.
ALONG AND BEHIND THE COLD FRONT LOW STRATUS IS SURGING ACROSS
NORTHERN NORTH DAKOTA...ADVECTING SOUTH AND EAST ACROSS THE STATE.
INCREASED SKY COVER USING THE 05Z RAP AS A STARTING POINT. BOTH
THE RAP AND 12Z NAM MAINTAIN SOME SORT OF LOW STRATUS THROUGH 15Z
FROM NORTHWEST INTO MY SOUTH CENTRAL.
&&
.AVIATION...
STRATUS WRAPPING AROUND LOW MOVING SOUTH AND EAST THROUGH THE
FORECAST AREA IS ON A TRAJECTORY TO MISS AERODROMES OF SOUTHWEST
NORTH DAKOTA. MVFR CIGS CAN BE EXPECTED NOW THROUGH 15Z FOR KMOT
AND KISN...AND KBIS AND KJMS AFTER 09Z UNTIL 15Z.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...NH
AVIATION...HW/NH
AREA FORECAST DISCUSSION
NWS 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
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 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 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 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...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 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 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 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 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 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 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 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