Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/22/14
AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
436 AM PST SAT DEC 20 2014
.SYNOPSIS...SCATTERED SHOWERS WILL CONTINUE ACROSS OUR AREA TODAY
AND SLOWLY DIMINISH TONIGHT. THIS WILL BE FOLLOWED BY A RIDGE OF
HIGH PRESSURE BUILDING OVER THE WEST COAST RESULTING IN A DRYING
AND WARMING TREND THROUGH AT LEAST MOST OF NEXT WEEK.
&&
.DISCUSSION...AS OF 3:10 AM PST SATURDAY...SURPRISING NUMBER OF
SHOWERS OVERNIGHT WITH 12 HOUR RAINFALL TOTALS QUITE A BIT ABOVE
EXPECTATIONS. IN FACT...PORTIONS OF SANTA CRUZ COUNTY ARE WELL
OVER AN INCH AND ON THEIR WAY TO HITTING 1.5 INCHES. CURRENT RADAR
LOOP SHOWS BULK OF ACTIVITY STRETCHING IN A BAND FROM SANTA CRUZ
AND SAN MATEO COUNTIES NE THROUGH SANTA CLARA COUNTY. HRRR SEEMS
TO HAVE DONE A FAIRLY GOOD JOB WITH SHOWING THE EVOLUTION AND
TENDED TO FAVOR IT FOR THE SHORT TERM FORECAST. IT INDICATES THAT
SHOWERS WILL BE ON THE DECREASE THROUGH THE DAY ALTHOUGH ALL
LOCATIONS WILL HAVE AT LEAST A SHOT AT GETTING LIGHT RAINFALL.
POPS WERE PUSHED UP FOR VIRTUALLY ALL SPOTS AND MAY HAVE BE
INCREASED EVEN MORE IF THEY SHOWERS DO NOT START TO DISSIPATE
BEFORE SUNRISE. IN GENERAL RAINFALL AMOUNTS WILL BE LIGHT TODAY
HOWEVER WOULD NOT BE SURPRISED IF A FEW LOCATIONS GET AN
ADDITIONAL HALF AN INCH BY TONIGHT.
A RIDGE OF HIGH PRESSURE ALONG WITH WARMER 850 MB READINGS WILL
START TO NOSE INTO OUR CWA TOMORROW AND REMAIN IN CONTROL AT LEAST
INTO TUESDAY. THIS WILL ALLOW FOR DRYING PLUS WARMER READINGS IN
ALL LOCATIONS. TUESDAY IS EXPECTED TO BE THE WARMEST DAY OF THE
WEEK WITH HIGHS IN THE 60S TO LOWER 70S.
AN INSIDE SLIDER WILL DROP DOWN CHRISTMAS EVE (WEDNESDAY) MOSTLY
IMPACTING AREAS TO OUR NORTH AND EAST WITH RAIN ANS SNOW.
HOWEVER...GUIDANCE CONTINUES TO SHOW THE SOUTHERN EXTENT OF THE
MOISTURE MOVING THROUGH OUR AREA ESPECIALLY THE NORTH BAY. THE
BIGGER IMPACT WILL BE TO COOL OFF TEMPERATURES BACK TO NEAR NORMAL
LEVELS. COULD ALSO SEE A FEW INLAND SPOTS DROPPING BACK INTO THE
MID 30S.
LONGER RANGE OUTLOOK GOING INTO 2015 HAS DRIER THAN NORMAL WEATHER
FORECAST. RIGHT NOW TRAVEL CONDITIONS FROM CHRISTMAS TO NEW YEARS
LOOK TO BE GOOD AROUND OUR AREA.
&&
.AVIATION...AS OF 4:15 AM PST SATURDAY...ABUNDANT LOW LEVEL
MOISTURE LEFT OVER FROM THE PAST SYSTEM IS BRINGING LOW CIGS TO
THE SFO BAY AREA. A FEW SHOWERS LINGER FROM THE SOUTH BAY TO THE
MRY BAY AREA. IFR CIGS EXPECTED TO LIFT TO MVFR AFTER 17Z AND VFR
BY 20Z AS THE NEXT APPROACHING SYSTEM PROVIDES SOME MIXING. RAIN
CONFINED TO THE NORTH BAY THIS AFTERNOON AND EVENING. PRESSURES
REMAINING STABLE SO SOUTHEAST WINDS STAYING BELOW 5 KT THROUGH THE
DAY.
VICINITY OF KSFO...IFR CIGS LIFTING TO MVFR AFTER 17-18Z AND VFR
AFTER 20Z. LIGHT SOUTHEAST WINDS 5 KT OR LESS THROUGH THE DAY.
KSFO BRIDGE APPROACH...SIMILAR TO KSFO.
MONTEREY BAY AREA TERMINALS...VFR CONDITIONS WITH CIGS 4000 FEET
OR ABOVE. ISOLATED LIGHT SHOWERS THROUGH 16Z.
&&
.MARINE...AS OF 4:15 AM PST SATURDAY...LARGE SWELLS HAVE ARRIVED
ALONG THE COAST. AS OF 4 AM...BUOYS REPORT SEAS RANGING FROM 21
FEET AT PT ARENA BUOY TO 13 FEET AT MONTEREY BAY BUOY. SWEL
PERIODS ARE 17-18 SECONDS. EXPECTING SEAS IN THE 17-20 FOOT RANGE
THIS MORNING DECREASING SLOWLY THIS AFTERNOON AND EVENING. HIGH
TIDE AROUND 8:30 AM COULD CAUSE MINOR COASTAL FLOODING NEAR THE
OCEAN. MAIN CONCERN WILL BE DURING KING TIDE SUNDAY MORNING AFTER
9 AM. ALTHOUGH SEAS WILL BE SLIGHTLY LOWER AND SWELL PERIOD WILL
BECOME 14-15 SEONDS...COASTAL FLOODING IS POSSIBLE IN THE SF BAY
AS WELL AS THE OCEAN.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.TDAY...HIGH SURF ADVISORY AND COASTAL FLOOD
ADVISORY...ALL COASTAL LOCATIONS TODAY
SCA...PT ARENA TO PT REYES 0-10 NM UNTIL 3 PM
SCA...PT REYES TO PIGEON PT 0-10 NM UNTIL 3 PM
SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 3 PM
SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM UNTIL 3 PM
SCA...PT ARENA TO PT REYES 10-60 NM UNTIL 3 PM
SCA...PT REYES TO PIGEON PT 10-60 NM UNTIL 3 PM
SCA...PIGEON PT TO PT PINOS 10-60 NM UNTIL 3 PM
SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM UNTIL 3 PM
SCA...ROUGH BAR ADVISORY FOR SF BAR
&&
$$
PUBLIC FORECAST: BELL
AVIATION/MARINE: W PI
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AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
313 AM PST SAT DEC 20 2014
.SYNOPSIS...SCATTERED SHOWERS WILL CONTINUE ACROSS OUR AREA TODAY
AND SLOWLY DIMINISH TONIGHT. THIS WILL BE FOLLOWED BY A RIDGE OF
HIGH PRESSURE BUILDING OVER THE WEST COAST RESULTING IN A DRYING
AND WARMING TREND THROUGH AT LEAST MOST OF NEXT WEEK.
&&
.DISCUSSION...AS OF 3:10 AM PST SATURDAY...SURPRISING NUMBER OF
SHOWERS OVERNIGHT WITH 12 HOUR RAINFALL TOTALS QUITE A BIT ABOVE
EXPECTATIONS. IN FACT...PORTIONS OF SANTA CRUZ COUNTY ARE WELL
OVER AN INCH AND ON THEIR WAY TO HITTING 1.5 INCHES. CURRENT RADAR
LOOP SHOWS BULK OF ACTIVITY STRETCHING IN A BAND FROM SANTA CRUZ
AND SAN MATEO COUNTIES NE THROUGH SANTA CLARA COUNTY. HRRR SEEMS
TO HAVE DONE A FAIRLY GOOD JOB WITH SHOWING THE EVOLUTION AND
TENDED TO FAVOR IT FOR THE SHORT TERM FORECAST. IT INDICATES THAT
SHOWERS WILL BE ON THE DECREASE THROUGH THE DAY ALTHOUGH ALL
LOCATIONS WILL HAVE AT LEAST A SHOT AT GETTING LIGHT RAINFALL.
POPS WERE PUSHED UP FOR VIRTUALLY ALL SPOTS AND MAY HAVE BE
INCREASED EVEN MORE IF THEY SHOWERS DO NOT START TO DISSIPATE
BEFORE SUNRISE. IN GENERAL RAINFALL AMOUNTS WILL BE LIGHT TODAY
HOWEVER WOULD NOT BE SURPRISED IF A FEW LOCATIONS GET AN
ADDITIONAL HALF AN INCH BY TONIGHT.
A RIDGE OF HIGH PRESSURE ALONG WITH WARMER 850 MB READINGS WILL
START TO NOSE INTO OUR CWA TOMORROW AND REMAIN IN CONTROL AT LEAST
INTO TUESDAY. THIS WILL ALLOW FOR DRYING PLUS WARMER READINGS IN
ALL LOCATIONS. TUESDAY IS EXPECTED TO BE THE WARMEST DAY OF THE
WEEK WITH HIGHS IN THE 60S TO LOWER 70S.
AN INSIDE SLIDER WILL DROP DOWN CHRISTMAS EVE (WEDNESDAY) MOSTLY
IMPACTING AREAS TO OUR NORTH AND EAST WITH RAIN ANS SNOW.
HOWEVER...GUIDANCE CONTINUES TO SHOW THE SOUTHERN EXTENT OF THE
MOISTURE MOVING THROUGH OUR AREA ESPECIALLY THE NORTH BAY. THE
BIGGER IMPACT WILL BE TO COOL OFF TEMPERATURES BACK TO NEAR NORMAL
LEVELS. COULD ALSO SEE A FEW INLAND SPOTS DROPPING BACK INTO THE
MID 30S.
LONGER RANGE OUTLOOK GOING INTO 2015 HAS DRIER THAN NORMAL WEATHER
FORECAST. RIGHT NOW TRAVEL CONDITIONS FROM CHRISTMAS TO NEW YEARS
LOOK TO BE GOOD AROUND OUR AREA.
&&
.AVIATION...AS OF 9:48 PM PST FRIDAY...A COLD FRONT CONTINUES TO
PASS OVER THE FORECAST AREA. PRECIPITATION IS NOW CONFINED TO SOUTH
OF THE SAN FRANCISCO BAY AREA. THE FRONT IS NO LONGER EXPECTED TO
BE STRONG ENOUGH TO MIX THE LOW CLOUDS OUT SO EXPECT MVFR CIGS AT
MOST TERMINALS OVERNIGHT. RAIN SHOULD END SHORTLY IN THE SAN JOSE
AREA BUT STICK AROUND UNTIL THE EARLY MORNING HOURS IN MONTEREY.
VICINITY OF KSFO...MVFR CIGS WILL PREVAIL THROUGH AROUND 1900Z
SATURDAY. ONCE THE CLOUDS LIFT ON SATURDAY VFR IS ANTICIPATED INTO
THE EVENING HOURS. WINDS ARE EXPECTED TO BE GENERALLY LIGHT
SOUTHERLY THROUGH THE FORECAST PERIOD.
CONFIDENCE IS MODERATE.
KSFO BRIDGE APPROACH...SIMILAR TO KSFO.
MONTEREY BAY AREA TERMINALS...MVFR CIGS AND LIGHT RAIN ARE
ANTICIPATED OVERNIGHT WITH RAIN ENDING BY SUN RISE. VFR IS
ANTICIPATED BY AROUND 1800Z SATURDAY.
CONFIDENCE IS MODERATE.
&&
.MARINE...AS OF 3:10 AM PST SATURDAY...A LARGE STORM IN THE GULF OF
ALASKA HAS GENERATED LARGE LONG- PERIOD SWELLS THAT WILL IMPACT
THE COASTAL WATERS THROUGH TONIGHT. SURFACE HIGH PRESSURE WILL
BUILD OFF THE CALIFORNIA COAST TONIGHT INTO EARLY NEXT WEEK
RESULTING IN INCREASING NORTHWEST WINDS OVER THE SOUTHERN WATERS
BEGINNING SUNDAY.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.TDAY...HIGH SURF ADVISORY AND COASTAL FLOOD
ADVISORY...ALL COASTAL LOCATIONS TODAY
SCA...PT ARENA TO PT REYES 0-10 NM UNTIL 3 PM
SCA...PT REYES TO PIGEON PT 0-10 NM UNTIL 3 PM
SCA...PIGEON PT TO PT PINOS 0-10 NM UNTIL 3 PM
SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM UNTIL 3 PM
SCA...PT ARENA TO PT REYES 10-60 NM UNTIL 3 PM
SCA...PT REYES TO PIGEON PT 10-60 NM UNTIL 3 PM
SCA...PIGEON PT TO PT PINOS 10-60 NM UNTIL 3 PM
SCA...PT PINOS TO PT PIEDRAS BLANCAS 10-60 NM UNTIL 3 PM
SCA...ROUGH BAR ADVISORY FOR SF BAR
&&
$$
PUBLIC FORECAST: BELL
AVIATION: LARRY
MARINE: W PI
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AREA FORECAST DISCUSSION...UPDATED
NWS RENO NV
903 PM PST FRI DEC 19 2014
.UPDATE...
IR SATELLITE SHOWED ABUNDANT MOISTURE STREAMING INTO NORTHERN CA
AND OREGON THIS EVENING WITH RAIN AND HIGHER ELEVATION SNOW MOVING
INLAND. BOTH THE 00Z GFS/NAM HAVE COME IN STRONGER WITH ASSOCIATED
WARM ADVECTION LATE TONIGHT INTO SAT MORNING WITH QPF SIGNATURE
FURTHER SOUTH OVER WESTERN NV. WE HAVE BUMPED UP POPS AND BROUGHT
THEM FURTHER SOUTH. STEADY PRECIPITATION WILL BRING UP TO 1/10 TO
1/4 INCH OF QPF NORTH OF HIGHWAY 50 06Z-18Z SAT WITH LOCALLY
HIGHER TOTALS NORTH OF SUSANVILLE AND GERLACH AND ALONG THE CREST
NORTH OF LAKE TAHOE. THIS WILL RESULT IN 2-4 INCHES OF SNOW FOR
ELEVATIONS ABOVE MOST VALLEY FLOORS (ABOVE 5000 FEET NORTH OF
SUSANVILLE AND GERLACH AND ABOVE 6500 FEET FURTHER SOUTH NEAR THE
I-80 CORRIDOR) WITH ONLY LIGHT ACCUMULATIONS SLIGHTLY BELOW THESE
LEVELS INCLUDING LAKE LEVEL IN THE TAHOE BASIN. AS THE WARM
ADVECTION WANES SAT AFTERNOON, PRECIPITATION WILL BECOME MORE
SHOWERY. HOHMANN
&&
.PREVIOUS DISCUSSION... /ISSUED 250 PM PST FRI DEC 19 2014/
SYNOPSIS...
CHANCES FOR RAIN AND SNOW WILL GRADUALLY DIMINISH FROM SOUTH TO
NORTH THROUGH SATURDAY. ANY AMOUNTS WILL REMAIN LIGHT. HIGH
PRESSURE WILL BUILD IN FOR EARLY NEXT WEEK WITH MILD TEMPERATURES.
A STRONG COLD FRONT IS POSSIBLE LATE WEDNESDAY INTO THURSDAY WITH
SOME GUSTY WINDS, RAIN AND SNOW.
SHORT TERM...
MAIN BAND OF RAIN/SNOW IS NOW ALONG A SOUTH LAKE TO BATTLE MTN.
LINE AND IS PUSHING SOUTH AND EAST. THIS BAND WILL WEAKEN OVER THE
NEXT FEW HOURS WITH LIGHT AMOUNTS UP TO A TENTH OF AN INCH.
OTHERWISE ONLY EXPECT ISOLD SHOWERS WITH ONE EXCEPTION. BOTH THE
NAM AND HRRR SHOW ANOTHER BAND OF PRECIP DEVELOPING OVER CENTRAL
CA AND MOVING NORTHEAST INTO THE TAHOE BASIN THIS EVENING. A WEAK
WAVE IS PRESENT IN SATELLITE IMAGERY NEAR 127W AND THIS LOOKS LIKE
IT WOULD BE THE TRIGGER. KEPT SCT SNOW SHOWERS GOING IN THE SIERRA
FROM CARSON TO YUBA PASSES FOR THIS WAVE ALTHOUGH IT MAY BE MORE
WIDESPREAD THAN THIS. ANOTHER COUPLE INCHES OF SNOW REMAIN
POSSIBLE IN THIS BAND IF IT DEVELOPS.
A MILD NIGHT TONIGHT WITH CONTINUED CLOUD COVER AS ANOTHER STORM
MOVES INTO OREGON FOR SATURDAY. WE WILL CONTINUE TO SEE ABUNDANT
CLOUD COVER, BUT THE FORCING WITH THIS NEXT STORM WILL REMAIN WILL
NORTH WITH THE UPPER JET INTO THE COLUMBIA RIVER. THE EXCEPTION
WILL BE NORTH OF A SUSANVILLE TO GERLACH LINE WHERE SOME GOOD
ISENTROPIC LIFT IS SHOWING UP SATURDAY MORNING. INCREASED THE
THREAT OF RAIN/SNOW THERE WHILE KEEPING IT LOW CHANCE TO SLIGHT
CHANCE FURTHER SOUTH. IT APPEARS THERE WILL BE ABOUT A TENTH TO
QUARTER INCH OF PRECIP WITH IT.
THE GREATEST UNCERTAINTY THERE WILL BE THE SNOW LEVEL AND PRECIP
TYPE ON VALLEY FLOORS. NORMALLY IN A GOOD WARM AIR ADVECTION EVENT
LIKE THIS IT WOULD START AS SNOW WITH SOME ISOTHERMAL TEMP
PROFILES. HOWEVER, SURFACE TEMPS AND DEWPOINTS ARE 35-40 AND SEE
NO SIGNIFICANT DRYING OR COOLING TONIGHT AS MOISTURE AND CLOUDS
CONTINUE TO ARRIVE. RIGHT NOW, PUT SNOW LEVELS 4500-5000 FEET WITH A
RAIN/SNOW MIX IN THE SURPRISE VALLEY. IF IT IS ALL SNOW 1-2 INCHES
OF SNOW IS POSSIBLE BUT MY GUESS IS IT WILL BE IN THE FORM OF
RAIN.
BEHIND THE WARM FRONT, MID/HIGH CLOUDS WILL DIMINISH SATURDAY
NIGHT INTO SUNDAY. SOME SCATTERED LOW CLOUDS WILL CONTINUE AS
ABUNDANT LOW LEVEL MOISTURE GETS TRAPPED UNDER A SUBSIDENCE
INVERSION WITH THE STRONG RIDGE BUILDING IN. TEMPERATURES WILL
REMAIN MILD AND ABOVE NORMAL INTO EARLY NEXT WEEK WITH 50S DURING
THE DAY AND 20S AND 30S OVERNIGHT, COLDEST IN SIERRA VALLEYS.
WALLMANN
LONG TERM...TUESDAY THROUGH FRIDAY...
HIGH PRESSURE OVER THE WEST WILL GIVE WAY AROUND MID WEEK AS A
FAST-MOVING LOW PRESSURE SYSTEM MOVES INTO THE WEST COAST ON
CHRISTMAS EVE. THE GFS KEEPS THE SYSTEM FLAT AS IT MOVES THROUGH
THE REGION WHILE THE ECMWF/UKMET ARE BRINGING A STRONGER, DIGGING
SYSTEM INTO THE REGION. THE NWS WEATHER PREDICTION CENTER CONCURS
WITH A DIGGING SYSTEM AND THIS SOUNDS APPROPRIATE AS STRONG
SHORTWAVE ENERGY MOVING OFF OF JAPAN SATURDAY ARRIVES AT THE WEST
COAST ON WEDNESDAY (WHICH WOULD ENHANCE THE SYSTEM).
AS FAR AS THE DETAILS, THE DEVIL REMAINS AS THE 12Z ECMWF AND GEM
ARE NOW IMPLYING SOME SPLITTING AS THE SYSTEM MOVES INTO THE SIERRA
AND WESTERN NEVADA. I WOULD STILL EXPECT PRECIPITATION (AT LEAST IN
THE SIERRA AND IN THE BASIN NORTH OF HIGHWAY 50) WHETHER THE SYSTEM
BEGINS TO SPLIT OR NOT, ESPECIALLY AS THE GFS/EC SHOW A MODERATE
MOISTURE FEED (PWATS APPROACHING ONE INCH) BEING PULLED OFF OF A
SUBTROPICAL LOW NEAR HAWAII. HOWEVER, THE SPLIT WOULD LOWER
PRECIPITATION TOTALS AS THE SYSTEM`S COLD FRONT WEAKENS/FRACTURES.
ALSO, IT WOULD DELAY THE PUNCH OF COLD AIR ENOUGH THAT PRECIPITATION
WOULD START AS RAIN INITIALLY BELOW 5000-5500 FEET RATHER THAN BE A
MAINLY SNOW EVENT PER THE UNSPLIT/CONSOLIDATED SOLUTIONS.
AS FAR AS IMPACTS FOR EASTERN CALIFORNIA AND WESTERN NEVADA FOR THE
CHRISTMAS HOLIDAY, WIND GUSTS TO 35-45 MPH IN THE LOWER ELEVATIONS
ARE POSSIBLE WEDNESDAY WHICH WOULD CLEAR OUT ANY HAZE/POLLUTANTS IN
THE VALLEYS AND WARM HIGHS INTO THE 50S TO NEAR 60. PRECIPITATION
WISE, SNOW OR RAIN AND SNOW MAY START TO MOVE INTO AREAS NORTH OF
INTERSTATE 80 BY LATE WEDNESDAY AFTERNOON, THEN ACROSS THE
RENO-TAHOE AREA DURING CHRISTMAS EVE. THOSE TRAVELING CHRISTMAS EVE
AND CHRISTMAS MORNING SHOULD KEEP AN EYE ON THE FORECAST WITH
POTENTIAL IMPACTS DUE TO SNOW IN THE SIERRA AND ON THE LOWER VALLEY
FLOORS.
AFTER THE SYSTEM PASSES, A COLD NORTH SURFACE FLOW IS EXPECTED TO
KEEP AFTERNOON HIGHS FOR VALLEYS ON THURSDAY/CHRISTMAS DAY AND
FRIDAY IN THE 30S. THE CAVEAT IS THAT IF AT LEAST A FEW INCHES OF
SNOW FALLS ON CHRISTMAS EVE HIGHS ARE LIKELY TO REMAIN IN THE 20S
ALL DAY FOR LATE NEXT WEEK. FOR LOWS, SNOWFALL WOULD PUSH LOWS FROM
THE SINGLE DIGITS AND TEENS TO BELOW ZERO FOR MANY VALLEY LOCATIONS.
SNYDER
AVIATION...
A FRONT MOVING THROUGH THE AREA IS PRODUCING -SN/SN AND IFR
CONDITIONS IN THE SIERRA WITH ISOLD/SCATTERED SHOWERS AND HIGHER
TERRAIN OBSCURATION IN WESTERN NEVADA, MAINLY NORTH OF HIGHWAY 50.
THE FRONT IS ALSO KICKING UP WINDS GUSTS TO 20-25 KTS IN WESTERN
NEVADA NEAR/SOUTH OF I-80 AND DOWN INTO EASTERN MONO COUNTY.
FINALLY, TURBULENCE AND LIGHT RIMING ARE ALSO A GOOD BET OVER THE
SIERRA AND INTO WESTERN NEVADA WITH A RECENT PIREP INDICATING THIS
BETWEEN 090-190 MSL NEAR RENO.
FOR THIS EVENING, ANOTHER UPPER DISTURBANCE APPROACHING THE NORTHERN
CALIFORNIA COAST IS EXPECTED TO ENHANCE NORTHERN SIERRA SNOWFALL.
GIVEN THAT THE NEXT ROUND OF SIERRA SNOW WILL ARRIVE AFTER SUNSET
THERE COULD BE AN INCH OR TWO OF ACCUMULATION ON UNTREATED TARMACS
AND RUNWAYS AT KTRK AND KTVL. PLENTY OF MOISTURE AND A FEW LEFTOVER
-SHSN SHOULD ALLOW AREAS OF LOW CIGS AND TERRAIN OBSCURATION TO
PERSIST OVERNIGHT FOR THE SIERRA AND PORTIONS OF NORTHEAST
CALIFORNIA.
SATURDAY, ONE MORE ROUND OF LIGHT LOWER VALLEY RAIN AND MOUNTAIN
SNOW WILL AFFECT NORTHEAST CALIFORNIA AND NORTHERN NEVADA. THIS WILL
MEAN HIGHER TERRAIN OBSCURATION AND PERIODS OF MVFR CIGS FOR
NORTHERN SIERRA (KTVL/KTRK) TERMINALS, AS WELL AS THE POSSIBILITY
FOR BRIEF MVFR CIGS OUT INTO WESTERN NEVADA NORTH OF INTERSTATE 80.
SNYDER
&&
.REV WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
CA...NONE.
&&
$$
FOR MORE INFORMATION FROM THE NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/RENO (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
848 PM MST SUN DEC 21 2014
.UPDATE...
ISSUED AT 847 PM MST SUN DEC 21 2014
SHOWERS HAVE ALSO MANAGED TO SPILL ACROSS THE FRONT RANGE AS
INSTABILITY HAS INCREASED THIS EVENING. THERE MAY BE SOME
POTENTIAL INSTABILITY WITH DRYING NOTED ALOFT...AND CELLS HAVE
BECOME QUITE CONVECTIVE WITH ISOLATED LIGHTNING INDICATED IN THE
COLORADO LIGHTNING MAPPING ARRAY. MEANWHILE...FRONT IS MOVING
ACROSS THE CO/WY BORDER AS OF 830 PM WITH ANOTHER AREA OF
PRECIPITATION...MOSTLY SNOW...BEHIND IT. HAVE INCREASED POPS FOR
MOST OF THE PLAINS TO ACCOUNT FOR BOTH OF THESE FEATURES. SHORT
RANGE RAP AND HRRR ARE NOT HANDLING THIS PRECIPITATION WELL AT
ALL. A FEW SPOTS COULD SEE AN INCH OR TWO OF SNOW ON THE PLAINS
IF SHOWERS BECOME MORE PERSISTENT AS INTENSITY/CONVECTIVE
PARAMETER IS THERE.
UPDATE ISSUED AT 652 PM MST SUN DEC 21 2014
BAND OF SHOWERS IS ORGANIZING ON THE EASTERN PLAINS EARLY THIS
EVENING...FROM NEAR CHEYENNE TO FORT MORGAN AND EAST OF LIMON.
THIS FEATURE SEEMS RATHER SLOW MOVING. MOST OF THIS WILL BE RAIN
BEFORE COLD FRONT ARRIVES LATER IN THE EVENING. THE ARRIVAL OF
THIS FEATURE AND A MORE NORTHERLY LOW LEVEL COMPONENT COULD SHIFT
THE BAND BACK TOWARD THE I-25 CORRIDOR OVERNIGHT...BUT STILL
FAVORING LOCATIONS EAST OF I-25. MOUNTAIN HEAVY SNOW EVENT IS
UNDERWAY WITH MOSTLY 3-6 INCH AMOUNTS BUT A FEW SPOTS ALREADY
APPROACHING A FOOT TOWARD THE COLUMBINE AND TOWER SNOTELS...AND
ALSO NEAR COPPER MOUNTAIN. THE HEAVIEST SNOW IS STILL ON TRACK TO
OCCUR THIS EVENING BUT THERE WAS SOME DRYING NOTED ON THE RIVERTON
WYOMING SOUNDING BETWEEN 700 MB AND 500 MB...WHICH SHOULD RESULT
IN LOWER SNOW INTENSITY AFTER MIDNIGHT. UNTIL THEN...ONE HALF TO
ONE INCH PER HOUR SNOW AMOUNTS WILL CONTINUE OVER MOST OF THE HIGH
COUNTRY. HAZARDOUS AND SLOW DRIVING CONDITIONS WILL REMAIN IN
PLACE THROUGH MONDAY WITH CONTINUED WINTER STORM WARNING.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 326 PM MST SUN DEC 21 2014
SNOW WILL CONTINUE IN THE MOUNTAINS OVERNIGHT TAPERING OFF
STARTING MONDAY EVENING. UPSTREAM OBS SHOW VISIBILITIES REDUCING
DOWN TO HALF A MILE WITH THE HEAVIER SNOW. CURRENT WARNING
PRODUCTS STILL ON TRACK BUT OVERNIGHT SHIFTS MAY NEED TO RE-ASSESS
END TIMES DUE TO RECENT MODEL RUNS MOVING THE JET OUT SOONER. THE
LINGERING MOISTURE AND OROGRAPHIC FLOW WILL STILL PRODUCE SOME
SNOW SHOWERS OVER THE MOUNTAINS TOMORROW BUT THE INTENSITY WILL
DECREASE. CONTINUING TO URGE TRAVELERS TO USE CAUTION AS WINDS
OVER THE HIGHER MOUNTAIN PASSES WILL GUST UP TO 60 MPH THIS
EVENING. CONSIDERABLE BLOWING AND DRIFTING SNOW ALONG WITH
VISIBILITIES BELOW A QUARTER OF A MILE WILL OCCUR OVER AREAS SUCH
AS LOVELAND PASS...BERTHOUD PASS AND RABBIT EARS PASS. OTHER WELL
TRAVELED AREAS ALONG I-70 SUCH AS THE TUNNEL WILL ALSO SEE GREATLY
REDUCED VISIBILITIES WITH ICY AND SNOWY ROADWAYS. TRAVELERS ARE
URGED TO USE CAUTION AND DELAY PLANS TO TRAVEL OVER THE MOUNTAINS
THIS EVENING IF AT ALL POSSIBLE.
FOR THE PLAINS DOWNSLOPING WINDS WILL KEEP AREAS ALONG THE
FOOTHILLS 4-5 DEGREES WARMER AND DRY WITH WINDS GUSTING UP TO 60
MPH OVER THE WIND PRONE AREAS. WINDS WILL MOVE TO A MORE NORTHERLY
DIRECTION EARLY TOMORROW MORNING BRINGING COOLER CONDITIONS ALONG
WITH A CHANCE OF SNOW EAST OF I-25. IN ADDITION TO THE INFLUX OF
MOISTURE OVER THE PLAINS THERE IS SOME INSTABILITY SO SOME AREAS
COULD HAVE SOME LIGHT ACCUMULATION...WITH UP TO 2 INCHES POSSIBLE
UNDER THE HEAVIER BANDS. TEMPERATURES FOR TOMORROW WILL BE COOLER
WITH HIGHS ONLY GETTING INTO THE LOWER 40S FOR THE PLAINS AND 20S
FOR THE MOUNTAINS. BOTH THE NAM AND GFS ARE SHOWING INCREASED
WINDS OVER THE NE PLAINS STARTING TOMORROW AFTERNOON. GFS
CURRENTLY HAS 65KTS AT 700 MB THAT COULD TRANSLATE TO WARNING
CRITERIA. WILL CONSULT WITH THE NEXT SHIFT AND FUTURE MODEL RUNS
ON POSSIBLE ISSUANCE.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 326 PM MST SUN DEC 21 2014
NORTHEAST COLORADO REMAINS UNDER THE INFLUENCE OF A BROAD UPPER
LEVEL TROUGH CENTERED OVER NEBRASKA AND A STRONG AND COLD NWLY
FLOW MONDAY NIGHT. BANDS OF INSTABILITY AND MOISTURE MOVING DOWN
THE WEST SIDE OF THIS TROUGH SHOULD KEEP SKIES MOSTLY
CLOUDY/OVERCAST AND SNOW CHANCES IN THE FORECAST FOR THE HIGH
PLAINS OVERNIGHT. HOWEVER AREAS ALONG THE BASE OF THE FRONT RANGE
MAY ESCAPE FROM ANY SNOWFALL DUE TO THE DRYING EFFECTS OF
DOWNSLOPE FLOW OFF THE FOOTHILLS AND CHEYENNE RIDGE. IN THE HIGH
COUNTRY...SNOWFALL WILL LIKELY CONTINUE OVERNIGHT...WITH MODERATE
SNOWFALL AT TIMES ON THE HIGHER RIDGES AND NORTHWEST FACING SLOPES
ALONG THE CONTINENTAL DIVIDE. GUSTY NORTHWEST WINDS MAY ALSO
CONTINUE TO PRODUCE SOME BLOWING SNOW IN OPEN TERRAIN. WITH
SNOWFALL LETTING UP AFTER MIDNIGHT...THE WINTER STORM WARNING FOR
MTN ZONES 31...33 AND 34 WILL BE ALLOWED TO EXPIRE AT MIDNIGHT
MST. MEANWHILE STRONG NWLY FLOW ALOFT GRADUALLY MIXES DOWNWARD
OVERNIGHT AS COLD ADVECTION INCREASES. BY EARLY TUESDAY MORNING
MODELS INDICATE N-NWLY SFC WINDS GUSTING TO AROUND 40 MPH ACROSS
THE NORTHEAST CORNER OF THE STATE. WITH SEVERAL INCHES OF SNOW
COVERING THE GROUND OUT THAT WAY...GOOD BET WE/LL SEE SOME BLOWING
SNOW.
DURING THE DAY TUESDAY...MODELS SHOW THE UPPER TROUGH TRACKING
SLOWLY NEWRD AWAY FROM COLORADO WITH NLY FLOW OVER THE PLAINS
BECOMING EVEN STRONGER DURING THE DAY. MODEL WIND SPEEDS ACROSS
THE NERN CORNER IN THE 35-50KT RANGE FOR MUCH OF THE DAY.
BLOWING SNOW WILL BE A GOOD BET ESPECIALLY IN OPEN AREAS OF
LOGAN...WASHINGTON...SEDGWICK AND PHILLIPS COUNTIES WHERE SEVERAL
INCHES OF SNOW ON THE GROUND. NO HIGHLIGHTS AT THIS TIME...HOWEVER
A HIGH WIND WARNING MAY BE NECESSARY SHOULD LATER MODEL RUNS
INDICATE EVEN STRONGER WIND SPEEDS. AS FOR SNOWFALL...SHOULD SEE
AN END TO IT BY MORNING AT LOWER ELEVATION AND BY LATE AFTERNOON
IN THE HIGH COUNTRY WITH THE START OF WARMING AND DRYING ALOFT.
ON WEDNESDAY..LARGE UPPER RIDGE OVER THE GREAT BASIN NUDGES EASTWARD
OVER COLORADO CLEARING SKIES AND WARMING TEMPERATURES. COULD SEE AN
8-10DEG F WARMUP IN MOST AREAS ON WEDNESDAY. WEDNESDAY NIGHT UPPER
RIDGE SHIFTS EAST AS THE NEXT IN A SERIES OF LONG WAVE TROUGHS
SWEEPS OVER THE PACIFIC NORTHWEST. LATEST INDICATIONS...AND THEY ARE
IN BETTER AGREEMENT TODAY...SHOW THIS TROUGH TRACKING NEARLY DUE
EAST ACRS THE NORTHERN ROCKIES. MODELS SHOW THE SOUTH SIDE OF
THIS TROUGH BRUSHING NORTHERN COLORADO CHRISTMAS DAY. AS IT DOES
MTNS AND HIGH VALLEYS SHOULD SEE A SHOT OF SNOW AND GUSTY WINDS
WHILE THE PLAINS REMAIN MILD AND DRY WITH GUSTY DOWNSLOPE FLOW
OFF THE FRONT RANGE. AS THE TROUGH PASSES LATE ON THURSDAY...MODELS
SHOW A BAND OF LIGHT PRECIP ASSOCIATED WITH COLD FRONT SLIPPING
SOUTH ACROSS NORTHEAST COLORADO DURING THE EVENING HOURS. SOME
AREAS MAY SEE SNOWFALL...BUT ANY AMOUNTS SHOULD BE LIGHT. BY LATE
THAT NIGHT...DRYING SETS IN ON COLD AND GUSTY NWLY WINDS.
FRIDAY AND SATURDAY LOOK DRY BUT WITH BELOW AVERAGE TEMPERATURES.
&&
.AVIATION...(FOR THE TAFS THROUGH 06Z MONDAY EVENING)
ISSUED AT 847 PM MST SUN DEC 21 2014
COLD FRONT IS EXPECTED TO REACH THE FRONT RANGE AIRPORTS TOWARD
05Z WITH WINDS TURNING MORE NORTHERLY AND GUSTING TO AROUND 25
KNOTS. SHOULD SEE A FEW RAIN SHOWERS WITH ILS LANDING CONDITIONS
TIL AROUND 06Z...THEN SNOW SHOWERS WITH IFR/MVFR CEILINGS AND
VISIBILITIES WITH SNOW SHOWERS. POTENTIAL FOR LOWER VISIBILITIES
OF ONE MILE OR LESS IF SHOWERS MAINTAIN THERE PRESENT
INTENSITY...WITH LOCAL SNOW ACCUMULATION UP TO AN INCH OR SO
POSSIBLE MAINLY ON GRASSY SURFACES. THOSE WOULD LIKELY BE ENDING
TOWARD 12Z AS DRIER AIR MOVES IN FROM THE NORTHWEST.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL MIDNIGHT MST MONDAY NIGHT FOR
COZ031>034.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST MONDAY NIGHT FOR
COZ030.
&&
$$
UPDATE...BARJENBRUCH
SHORT TERM...BOWEN
LONG TERM...BAKER
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS PUEBLO CO
835 PM MST SUN DEC 21 2014
.UPDATE...
ISSUED AT 831 PM MST SUN DEC 21 2014
ANOTHER UPDATE TO RAISE POPS OVER THE ERN PLAINS WHERE PERSISTENT
LIGHT BANDED RAIN SHOWERS HAVE BEEN MOVING...ALTHOUGH MOST OF THE
PRECIP NOT LIKELY REACHING THE GROUND. ALSO BUMPED UP POPS FOR THE
NRN SAN LUIS VALLEY WHERE PERSISTENT LIGHT SNOW HAS BEEN FALLING.
LATEST HRRR SHOWS PRECIP DIMINISHING FOR THE PLAINS EARLY MON
MORNING. ROSE
UPDATE ISSUED AT 544 PM MST SUN DEC 21 2014
UPDATED GRIDS/ZONES PER LATEST OBS AND RADAR TRENDS AS WELL
AS LATEST HI RES GUIDANCE. MAIN CHANGES WERE TO BUMP UP POPS
SLIGHTLY OVER THE DVD SO THAT CATEGORICAL POPS ARE THERE FOR THE
HIGHER ELEVATIONS...AND ADDED BORDERLINE MENTIONABLE (10 PERCENT)
POPS FOR EL PASO COUNTY THIS EVE. LOOKS LIKE MOST OF THE PRECIP
WILL STAY OUT OVER KIOWA COUNTY...BUT CANNOT RULE OUT SOME SMALL
BANDS OF SHOWERS MOVING OVER THE I-25 CORRIDOR AS WELL. ROSE
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 320 PM MST SUN DEC 21 2014
...HEAVY SNOW TO CONTINUE IN THE MTNS...
CURRENTLY...
RADAR AND SFC OBS SHOW WIDESPREAD SNOW IN THE HIGH COUNTRY. KLXV
WEBCAMS SHOW SOME PRETTY DECENT ACCUMS IN TOWN. KGJT SHOWS
WIDESPREAD PRECIP ALONG THE WEST SLOPE MOVING RAPIDLY SE IN THE
STRONG NW FLOW ALOFT. AT LOWER ELEVATIONS...WIDESPREAD HIGH
CLOUDINESS DOMINATES ACROSS THE PLAINS. TEMPS WERE MILD WITH MAINLY
50S...WITH THE WARMEST TEMPS AT CANON CITY AND KSPD. GUSTY WINDS
PREVAILED IN THE MTNS AND GAP AREAS...WITH WINDS GUSTING TO 40 MPH
IN GAP AREAS.
TODAY THRU TONIGHT...
HEAVY WIND DRIVEN SNOW WILL CONTINUE ACROSS THE C MTNS AND NW SLOPES
OF THE LA GARITA MTNS. A FOOT OR MORE OF ADDITIONAL SNOW IS NEAR
CERTAIN.
OVER THE REMAINDER OF THE MTNS...SNOW OVER THE HIGH COUNTRY IS
EXPECTED TO GRADUALLY DROP SOUTHEAST WITH TIME...AND SNOW SHOULD BE
INCREASING MOST MTN AREAS AFTER MIDNIGHT. THE NORTHERN SAN LUIS
VALLEY SHOW START TO SEE SNOW DURING THE EARLY MORNING HOURS. A FEW
SNOW SHOWERS WILL BE POSSIBLE ON THE PLAINS...BUT NO SIGNIF ACCUMS
ARE ANTICIPATED.
AMBIENT TEMPS TONIGHT SHOULD REMAIN RELATIVELY MILD...WITH LOWS
IN THE U20S PLAINS...AND TEENS AND 20S MTNS. WITH THE STRONG WINDS
OVER THE HIGHER TERRAIN...WIND CHILLS WILL BE SHARPLY COLDER.
WINDS OVER THE MTNS WILL RANGE IN THE 30-50 MPH RANGE TONIGHT.
TOMORROW...
SNOW...HEAVY AT TIMES...WILL CONTINUE IN THE MTNS ALONG THE CONTDVD
AND NW FACING SLOPES OF THE LA GARITAS. SNOW WILL LIKELY SLACKEN
AS THE AFTERNOON PROGRESSES TOMORROW. WINDS WILL LESSEN A BIT OVER
THE HIGHER TRRN BUT WILL INCREASE ACROSS THE PLAINS BY AFTERNOON
AS THE STRONG JET MOVES OUT OVER THE MTNS AND LAPSE RATES INCREASE
AS COLDER AIR MOVE IN ALOFT. BY MIDAFTERNOON TOMORROW...LAPSE
RATES WILL INCREASE TO 8-9 C/KM AND THIS WILL ALLOW FOR CONVECTIVE
SNOW SHOWERS TO DEVELOP OVER THE PLAINS. THE BEST CHANCE OF SNOW
SHOWERS AT LOWER ELEVATIONS WILL BE OVER THE PALMER DIVIDE AND THE
EAST FACING SLOPES OF THE WETS/SANGRES AND RATON MESA/SPANISH
PEAKS REGIONS.
IT WILL BE COLDER TOMORROW OVER THE PLAINS...WITH TEMPS 10F OR SO
COLDER THAN TODAY. IT WILL FEEL MUCH COLDER AS THE WINDS INCREASE
FROM THE NW DURING THE AFTERNOON. HI TEMPS TOMORROW WILL LIKELY
OCCUR AROUND OR SHORTLY AFTER NOONTIME.
I CANNOT RULE OUT SOME SNOW BANDS DROPPING A COUPLE INCHES OF SNOW
ON THE PLAINS TOMORROW. HOWEVER...GUIDANCE HAS BEEN GRADUALLY
BACKING OFF ON THIS SCENARIO. WHERE THESE BANDS SET UP IS ANYONES
GUESS...BUT THE OVERALL BEST CHANCE OF ANY PRECIP AT THE LOWER
ELEVATIONS APPEARS TO BE ON THE PALMER DVD AND SPANISH PEAKS/RATON
MESA REGION (LAS ANIMAS/HUERFANO COUNTY REGION).
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 320 PM MST SUN DEC 21 2014
MONDAY NIGHT AND TUESDAY...THE UPPER LOW OVER THE MIDWEST MONDAY
NIGHT WILL SLIDE GRADUALLY TO THE NE TOWARDS THE GREAT
LAKES...ELONGATING THE UPPER TROUGH DOWN INTO TX TUE MORN. THIS WILL
ALLOW THE 140 KT UPPER JET TO DROP DOWN INTO WESTERN CO AND CREATE
VERY STRONG WINDS FOR THE FORECAST AREA. SO...ONGOING WINTER
HIGHLIGHTS WILL END MON EVE AND THE THREAT THEN BECOMES MORE OF A
WIND PROBLEM AS OPPOSED TO A SNOW ACCUMULATION PROBLEM. SNOW IS
EXPECTED TO LINGER OVER THE E PLAINS AND SOUTHERN FOOTHILLS THROUGH
TUE MORN...BUT VERY STRONG NORTHERLY WINDS TUE AFTN AND EVE ARE
EXPECTED...AND EVEN THOUGH AIR TEMP SHOULD BE IN THE MID TO UPPER
30S...WIND CHILLS WILL BE IN THE TEENS TO EVEN SINGLE DIGITS.
TUESDAY NIGHT AND WEDNESDAY...THIS STILL LOOKS TO BE A TRANSITIONAL
DAY AS NORTHERLY FLOW BECOMES MORE WESTERLY THROUGH WED AFTN AHEAD
OF THE NEXT APPROACHING SYSTEM. TEMPS ARE EXPECTED TO REBOUND INTO
THE MID TO UPPER 40S FOR THE PLAINS...AND INTO THE UPPER 30S TO 40S
FOR THE HIGH VALLEYS.
THURSDAY THROUGH SUNDAY...MODELS ARE HAVING A HARD TIME COMING UP
WITH A SOLUTION FOR CHRISTMAS AND THE WEEKEND. BOTH EC AND GFS ARE
INDICATING ANOTHER TROUGH MOVING IN...BUT KEEPING MUCH OF THE
ACTIVITY TO THE NORTH. IT LOOKS LIKE THE CONTDVD AND ESPECIALLY THE
CENTRAL MTS ARE SET UP TO GET SOME MORE SNOW STARTING VERY EARLY THU
MORNING AND LASTING THROUGH FRI...THOUGH THE EC ALSO SHOWS SOME PCPN
WITH A COLD FRONT PASSAGE FOR THE PLAINS LATE THU. FEEL THAT IS
HIGHLY SUSPECT...SO EVEN THOUGH ISOLATED POPS ARE INCLUDED FOR THE
PALMER DVD AND EL PASO COUNTY...KEPT MUCH OF THE E PLAINS DRY.
CLOUDY AND A BIT WINDY...BUT DRY. EXPECT A RATHER MILD DAY ON THU
AHEAD OF THIS SYSTEM...THEN 15 TO 20 DEGREES COLDER ON FRI. AS FOR
SAT AND SUN...MODEL DISAGREEMENT CONTINUES...THOUGH A GENERAL
WESTERLY FLOW ALOFT LOOKS TO BE IN PLACE THROUGH SUN. FEEL THE BEST
BET IS TO INCLUDE ISOLATED POPS FOR THE HIGHER ELEVATIONS ON SUN
WITH A GRADUAL WARMING TREND THROUGH THE WEEKEND. MOORE
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 320 PM MST SUN DEC 21 2014
STRONG PACIFIC JET MOVING INTO THE MTNS THIS AFTERNOON WILL
GRADUALLY SPILL OUT ONTO THE PLAINS TONIGHT.
KCOS...
SHOULD REMAIN DRY THROUGH AT LEAST SUNRISE...WITH SOME SHRA
TOMORROW MORNING. BETTER CHANCE OF SOME SNOW WILL BE TOMORROW
AFTERNOON. TEMPS WILL LIKELY REMAIN AT OR ABOVE FREEZING TOMORROW SO
SNOW SHOULD NOT ACCUMULATE ON PAVED RUNWAYS. HOWEVER...IF A LOCALLY
SNOW BAND DEVELOPS THEN IT WILL BE POSSIBLE FOR SOME ACCUM SNOW OVER
THE THE KCOS AREA. FOR NOW THE PROBABILITY OF THIS LOOKS TO LOW TO
EXPLICITLY MENTION IN THE TAF. GUSTY NORTHWEST WINDS WILL DEVELOP BY
AFTERNOON.
KALS..
BEST CHANCE OF PRECIP WILL BE LATE TONIGHT AND ESPECIALLY
TOMORROW AS BEST FORCING MOVES OVER AREA AND LAPSE RATES INCREASE.
NORTHWEST WINDS WILL INCREASE TOMORROW WITH GUSTS TO 30 MPH LIKELY
BY AFTERNOON.
KPUB...
WILL LIKELY REMAIN VFR THROUGH THE 24H PERIOD. HOWEVER...CANNOT RULE
OUT A PERIOD OF SNOW SHOWERS TOMORROW WHICH COULD REDUCE VISIBILITY
FOR A SHORT WHILE TO MVFR.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 5 PM MST MONDAY FOR COZ064-066.
WINTER WEATHER ADVISORY UNTIL 11 PM MST MONDAY FOR COZ061.
WINTER STORM WARNING UNTIL 11 PM MST MONDAY FOR COZ058>060.
&&
$$
UPDATE...ROSE
SHORT TERM...HODANISH
LONG TERM...MOORE
AVIATION...HODANISH
AREA FORECAST DISCUSSION
NWS TAUNTON MA
958 AM EST SAT DEC 20 2014
.SYNOPSIS...
SCATTERED SNOW/RAIN SHOWERS WILL GRADUALLY OVERSPREAD THE REGION
FROM EAST TO WEST LATER TODAY INTO SUN. WEAK LOW PRESSURE WILL
PASS SOUTH OF NEW ENGLAND BRINGING ANOTHER PERIOD OF PRECIP MON
NIGHT AND TUE. A MUCH STRONGER STORM PASSING WEST OF NEW ENGLAND
WILL BRING HEAVY RAINFALL...GUSTY WINDS AND COASTAL FLOODING
CONCERNS TO THE REGION WED INTO WED EVENING. DRY BUT VERY WINDY
CONDITIONS FOLLOW FOR CHRISTMAS DAY INTO FRI.
&&
.NEAR TERM /UNTIL NOON TODAY/...
10 AM UPDATE...MADE MINOR UPDATES MAINLY TO THE WINDS AND POPS.
UPDATED WINDS USING THE RAP FOR ITS HIGHER DETAIL WITH THE COASTAL
FRONT THIS AFTERNOON. SNOW SHOWERS HAVE MOVED ASHORE IN PLYMOUTH
COUNTY AS WELL AS PORTIONS OF THE CAPE AND THE EASTERN END OF CAPE
ANN. EXPECT THESE TO CONTINUE OFF AND ON THROUGH THE REMAINDER OF
THE MORNING.
SATELLITE IMAGERY SHOWS AN INTERESTING PATTERN. LOW CLOUDS MOVING
WESTWARD OFF THE OCEAN HAVE CREPT IN ALONG THE EAST COAST. THEN
ANOTHER AREA OF LOW CLOUDS HAVE MOVED NORTHWARD TOO ABOUT THE MASS
PIKE. NORTHWESTERN MASS SHOULD REMAIN MOSTLY SUNNY THROUGH THE
MORNING AND INTO THE AFTERNOON WHILE CLOUDS CONTINUE TO MOVE
WESTWARD ACROSS EASTERN MASSACHUSETTS.
&&
.SHORT TERM /NOON TODAY THROUGH 6 PM SUNDAY/...
THIS AFTERNOON AND TONIGHT...
INTERESTING MESOSCALE SETUP AS AN INVERTED TROUGH COMBINES WITH SOME
OCEAN ENHANCEMENT. APPROACHING UPPER LEVEL SHORTWAVE WILL ALLOW FOR
EASTERLY FLOW JUST OFF THE GROUND. THIS COMBINED WITH NORTHEAST
SURFACE WINDS WILL ALLOW LOW LEVEL OF THE ATMOSPHERE TO MOISTEN.
SOUNDINGS ACROSS EASTERN NEW ENGLAND BECOME SATURATED ALL THE WAY UP
TO THE -9C LAYER JUST ABOVE 850 MB. THIS IS FAVORABLE FOR SOME
DECENT SNOW GROWTH...ITS JUST LOWER IN THE ATMOSPHERE THAN WE
TYPICALLY SEE WITH MORE SYNOPTIC SNOW EVENTS. WHILE THIS IS NOT A
TRUE OCEAN EFFECT EVENT...DELTA T VALUES FROM THE MIXED LAYER TO THE
OCEAN ARE AROUND 15C. THEREFORE...EXPECT SOME OCEAN ENHANCEMENT.
TIMING:
WHILE FLURRIES/LIGHT SNOW SHOWERS MAY OCCUR ACROSS FAR SOUTHEAST NEW
ENGLAND THIS MORNING. THE MORE SUBSTANTIAL PRECIPITATION SHOULD
OVERSPREAD PLYMOUTH COUNTY AS WELL AS THE CAPE AND ISLANDS THIS
AFTERNOON. GIVEN EASTERLY FLOW JUST OFF THE GROUND...EXPECT SNOW
SHOWERS TO OVERSPREAD MOST OF EASTERN NEW ENGLAND THIS EVENING AS
LOW LEVELS MOISTEN. IN FACT...SHOULD SEE AT LEAST SOME SCATTERED
SNOW SHOWERS AFFECT EVEN OUR FAR WESTERN ZONES.
PTYPE:
MAINLY SNOW FOR ALL BUT PORTIONS OF COASTAL PLYMOUTH COUNTY AND ONTO
THE CAPE/ISLANDS. A SUBTLE COASTAL FRONT LOOKS TO SETUP ACROSS
SOUTHEAST COASTAL PLYMOUTH COUNTY. PTYPE WILL BE SNOW TO THE
NORTHWEST OF THIS REGION...BUT ENOUGH MILD AIR SHOULD COME IN OFF
THE OCEAN FOR A CHANGE TO RAIN SHOWERS SOUTHEAST OF THIS REGION.
NOT EXPECTING THE POSITION OF THIS SUBTLE BOUNDARY TO CHANGE MUCH
THROUGH SUNDAY MORNING.
SNOW ACCUMULATIONS:
WE ARE GENERALLY LOOKING AT A COATING TO 2 INCHES OF SNOW ACROSS
MOST OF THE REGION. THE MAIN FOCUS FOR 1 TO 2 INCHES WILL BE ACROSS
PORTIONS OF SOUTHEAST MA...AWAY FROM THE SOUTHEAST PLYMOUTH COUNTY
COAST. ALSO...THE WORCESTER HILLS INTO NORTHWEST RHODE ISLAND MIGHT
BE ANOTHER AREA AS A RESULT OF THE SUBTLE UPSLOPE COMPONENT TO THE
WIND. YOU CAN ACTUALLY SEE THAT IN SOME OF THE HIGH RESOLUTION
MODEL GUIDANCE.
THERE IS ONE AREA TO WATCH IN PARTICULAR...FROM NORTHWEST PLYMOUTH
COUNTY AND INTO NORFOLK COUNTY BASED ON MESOSCALE MODELS AND PATTERN
RECOGNITION. WOULD NOT BE SURPRISED TO SEE VERY LOCALIZED 3 TO 4
INCH SNOW AMOUNTS...GIVEN SOME OCEAN ENHANCEMENT AND A LITTLE FOCUS
ON THE COASTAL FRONT. WILL TRY TO HIGHLIGHT THIS AREA IN OUR
SNOWFALL AND PROBABILISTIC GRAPHICS.
SUNDAY...
SCATTERED SNOW SHOWERS WILL CONTINUE DURING THE MORNING WITH MOIST
EASTERLY FLOW IN THE LOW LEVELS. AGAIN...PTYPE WILL BE SNOW EXCEPT
ACROSS SOUTHEAST PLYMOUTH COUNTY/CAPE AND ISLANDS WHERE BOUNDARY
LAYER WILL PROBABLY BE WARM ENOUGH FOR RAIN SHOWERS. WHILE SOME
LIGHT PRECIPITATION MAY LINGER INTO SUNDAY AFTERNOON...EXPECT A
DECREASE IN AREAL COVERAGE THROUGH THE AFTERNOON AS LOW LEVEL LIFT
WEAKENS. IT WILL REMAIN CLOUDY THOUGH WITH TEMPS IN THE 30S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HIGHLIGHTS...
* INVERTED TROUGH WILL BRING RAIN/SNOW SHOWERS TO THE MASS EAST
COASTLINE MONDAY INTO TUES MORNING.
* WEAK WAVE OF LOW PRESSURE MON NIGHT/TUESDAY COULD BRING WINTRY
MIX TO INTERIOR
* ANOMALOUS SYSTEM ACROSS THE GREAT LAKES WILL BRING HEAVY
RAIN...GUSTY WINDS AND COASTAL FLOODING CONCERNS AROUND CHRISTMAS
EVE
OVERVIEW...
OVERALL 00Z GUIDANCE IS IN AGREEMENT SYNOPTICALLY WITH ISSUES ON
TIMING AND SMALLER SCALE FEATURES. IT REMAINS EVIDENT THAT AN
AMPLIFIED MID-UPPER LEVEL TROUGH AND PCPN FOCUSING LEAD SURFACE
LOW/FRONTAL SYSTEM WILL STEADILY PROGRESS TO THE EAST-CENTRAL U.S.
TUE AS EMBEDDED IMPULSES DIG TO THE LEE OF AN AMPLIFIED ERN
PACIFIC/WEST COAST RIDGE ALOFT. THE SUPPORTING AND INCREASINGLY
NEGATIVE-TILT TROUGH ALOFT WORKS OVER THE ERN US AND OUT THROUGH THE
NERN STATES INTO DAYS 4/5 WED/THU. MODELS/ENSEMBLES HAVE BEEN
FAIRLY CONSISTENT ON THIS AMPLIFIED PATTERN AND THE MOST RECENT
GEFS/ECMWF ENSEMBLE GUIDANCE SHOW GOOD CORRELATION TO NEXT THURSDAY.
HIGH PRESSURE AND UPPER LEVEL RIDGE OVER THE REGION WILL BEGIN TO
EXIT BY MONDAY. AT THE SURFACE APPEARS ANOTHER INVERTED
TROUGH/ONSHORE FLOW WILL YIELD TO PRECIP ALONG THE MASS COASTLINE ON
MONDAY. ASIDE FROM THIS QUICK MESOSCALE EVENT THE MAIN FOCUS IS ON
THE LONGWAVE DIGGING TROUGH OVER THE CENTRAL CONUS WHICH WILL PUSH A
FEW SHORTWAVES THROUGH THE FLOW. FIRST ONE DEVELOPS A WEAK WAVE
MOVING TOWARDS THE REGION LATE MONDAY INTO TUESDAY. THERE IS STILL
SOME UNCERTAINTY WITH THE LOCATION/STRENGTH OF THIS SYSTEM BUT
APPEARS THAT THERE IS THE POSSIBILITY OF A SNOW/WINTRY MIX IN THE
INTERIOR. AS THIS SYSTEM DEPARTS AN ANOMALOUS LOW OVER THE GREAT
LAKES WILL DEVELOP A SECONDARY LOW JUST WEST OF SOUTHERN NEW ENGLAND
PER ENSEMBLE GUIDANCE. STILL A SOME SPREAD BUT IF THIS DOUBLE LOW
DOES DEVELOP THEN THE RAIN AND WIND ASPECT OF THE SYSTEM
INCREASES...DETAILS BELOW. STILL NEED TO WORK OUT MINOR DETAILS WITH
THIS PARTICULAR SYSTEM BUT WITH 3 TO 4 STANDARD DEVIATIONS AWAY AND
GENERAL MODEL AGREEMENT HAVE HIGH CONFIDENCE THIS SYSTEM WILL IMPACT
SOUTHERN NEW ENGLAND.
DETAILS...
SUNDAY NIGHT INTO TUESDAY...MODERATE CONFIDENCE.
HIGH PRESSURE AND UPPER LEVEL RIDGE WILL BEGIN TO MOVE OFFSHORE AS
DIGGING TROUGH BEGINS TO SET-UP OVER THE CENTRAL CONUS. APPEARS
ANOTHER MESO-SCALE INVERTED TROUGH WILL SET UP ON MONDAY AND LAST
INTO EARLY TUESDAY MORNING. GUIDANCE SHOWS THAT RAIN/SNOW SHOWERS
WILL DEVELOP ALONG THE MASS EAST COASTLINE THANKS TO ONSHORE
EASTERLY FLOW. APPEARS THE COLUMN WILL SATURATE PER BUFKIT SOUNDINGS
AND SOUTHERLY FLOW ALOFT. BOTH THE NAM AND GFS SHOW QPF MAKING IT
ONSHORE DURING THIS TIME FRAME. HOWEVER THE EC IS SLIGHTLY SLOWER
AND KEEP THE BULK OF THE PRECIP JUST OFFSHORE. ADD A CHANCE OF POPS
DUE TO THE NAM/GFS MODEL CONTINUITY.
BY LATE MONDAY NIGHT INTO TUESDAY A SOUTHERN BRANCH STORM SYSTEM
FORMS ALONG THE SE COAST AND TAKES A TRACK OFF THE MID ATLANTIC
COAST. THIS SYSTEM GETS CAUGHT UP WITH THE OVERALL LARGE SCALE
AMPLIFICATION OF THE UPPER AIR PATTERN. THERE IS DECENT WARM
ADVECTION WITH COLD AIR DAMMING ACROSS THE INTERIOR. BIGGEST
QUESTION WILL BE IS THERE ENOUGH MOISTURE FOR PRECIP DURING THIS
TIME FRAME. IF PRECIP OVERRUNS THEN COULD SEE FREEZING RAIN/DRIZZLE
ACROSS THE INTERIOR LATE MONDAY INTO TUESDAY MORNING. DURING THE DAY
ON TUESDAY...GOOD AMOUNT OF WARM AIR WILL PUSH SURFACE TEMPS ABOVE
FREEZING ALLOWING FOR ANY PRECIP TO BE MORE OF THE LIQUID VARIETY
AHEAD OF THE CHRISTMAS EVE STORM. HOWEVER GUIDANCE IS ALWAYS TOO
FAST IN SCOURING TEMPS OUT ESP ACROSS THE CT VALLEY SO WE WILL NEED
TO MONITOR THIS CLOSELY...ESP DUE TO LIGHT WINDS AND THE HIGH IN
EASTERN CANADA.
WE COULD ALSO SEE SOME MINOR COASTAL FLOODING CONCERNS ON TUESDAY. SEE
BELOW FOR MORE DETAILS.
WEDNESDAY INTO THURSDAY...HIGH CONFIDENCE IN SYSTEM LOW CONFIDENCE
ON DETAILS.
STRONG ANOMALOUS SYSTEM WILL STRENGTHEN OVER THE GREAT
LAKES...DEVELOPING A POTENTIAL SECONDARY SURFACE LOW JUST WEST OF
SOUTHERN NEW ENGLAND. STILL A LOT OF DETAILS TO WORK OUT AS THIS
SYSTEM IS STILL 5 DAYS AWAY...HOWEVER ENSEMBLES CONTINUE TO SHOW
STRONG AGREEMENT SO HAVE INCREASING CONFIDENCE THAT A POTENT STORM
WILL OCCUR. LATEST 00Z GUIDANCE SHOWS THAT MOST PRECIP WILL BE
LIQUID WITH A DEEP SUBTROPICAL CONNECTION BACK ACROSS THE GULF OF
MEXICO...PW ANOMALIES FORECAST TO RISE BETWEEN +3 TO +4. CURRENT
PWATS ARE PROGGED ABOVE 1.6 INCHES SO HAVE CONTINUED THE CATEGORICAL
POPS. TEMPERATURES WILL BE WELL ABOVE AVERAGE...IN FACT WE MAY BE
CLOSE AT BREAKING RECORD HIGH TEMPS IF TEMPS WARM TO 60F OR ABOVE ON
CHRISTMAS EVE. AS THE SYSTEM WRAPS UP INTO CANADA...COLD AIR
ADVECTION SHOULD CIRCULATE AROUND AND BEGIN A TRANSITION FROM
SOUTHWEST TO NORTHEAST IN TURNING P-TYPE TO SNOW. HOWEVER LATEST
GUIDANCE DOES SHOW A QUICK MOVING DRY SLOT SO SNOWFALL WILL STRUGGLE
DUE TO LACK OF MOISTURE.
THIS SYSTEM IS QUITE POTENT SO WE WILL NEED TO WATCH FOR POTENTIAL
HAZARDS. CURRENTLY THINK THAT WE COULD POSSIBLE URBAN FLOODING
ISSUES AS MODELS PROGGED WELL OVER 1.5 INCHES OF QPF. LATEST EC EVEN
SHOWS 2.5 INCHES OF QPF IS POSSIBLE. THE GEFS SHOW A MOISTURE FLUX
AT 850 MB BEING 4 TO 5 STANDARD DEVIATIONS AWAY...AND WITH THE
TROPICAL CONNECTION AND STRONG SOUTHERLY FLOW COULD SEE HIGHER
AMOUNTS DUE TO TOPOGRAPHY ENHANCEMENTS. RAIN FALL RECORDS MAY FALL
IF EVERYTHING FALLS INTO PLACE.
ALSO BELIEVE THAT WE MAY SEE SOME WIND ISSUES WITH THIS SYSTEM.
GUIDANCE RIGHT NOW IS SHOWING A 45 TO 55 KT JET AT 925 MB...HOWEVER
IT WILL BE HARD TO BREAK THE INVERSION WITH THE SOUTHERLY FLOW.
RIGHT NOW BELIEVE THAT WIND ADVISORIES MAY BE NEEDED BUT IF THIS
SYSTEM STRENGTHEN EVEN MORE SO A STRONGER JET IS POSSIBLE.
CONTINUED THE MENTIONED OF ISOLATED THUNDER IN THE FORECAST PER PREV
FORECASTER SUGGESTION. BELIEVE IT COULD BE POSSIBLE AS SOUTHERN NEW
ENGLAND WILL BE IN THE WARM SECTOR...WITH THE ANOMALOUS JET AND
SHOWALTERS CLOSE TO ZERO.
FRIDAY...LOW CONFIDENCE.
ONCE UPPER LEVEL LOW MOVES INTO SOUTHERN CANADA...EXPECT A RATHER
FAST UPPER W FLOW IN PLACE. MAY SEE LEFTOVER SNOW SHOWERS BUT TEMPS
WILL FALL BACK CLOSE TO SEASONAL NORMS.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT TERM /THROUGH SUNDAY/...
700 AM UPDATE...
TODAY...MODERATE CONFIDENCE. MVFR CIGS WILL CONTINUE TO OVERSPREAD
EASTERN NEW ENGLAND THIS MORNING AND EVENTUALLY INTO THE INTERIOR
THIS AFTERNOON. SCATTERED PRECIPITATION WILL OVERSPREAD
SOUTHEAST MA/CAPE/ISLANDS THIS AFTERNOON. PTYPE MAINLY SNOW SHOWERS
NORTHWEST OF THE SOUTHEAST PLYMOUTH COUNTY COAST AND RAIN SHOWERS
SOUTHEAST OF THAT REGION. LOCALIZED IFR CONDITIONS POSSIBLE JUST
INLAND FROM THE SOUTHEAST NEW ENGLAND COAST...WHERE PTYPE IS SNOW.
TONIGHT AND SUNDAY...MODERATE CONFIDENCE. MVFR CONDITIONS DOMINATE
IN LOWER CLOUDS AND SCATTERED PRECIPITATION. LOCALIZED IFR
CONDITIONS POSSIBLE WITH THE BEST CHANCE IN SNOW SHOWERS.
PRECIPITATION AFFECTS MAINLY EASTERN NEW ENGLAND BUT STILL SOME
SCATTERED ACTIVITY ACROSS WESTERN NEW ENGLAND. PTYPE MAINLY SNOW
SHOWERS NORTHWEST OF THE SOUTHEAST PLYMOUTH COUNTY COAST...WITH RAIN
SHOWERS SOUTHEAST OF THAT REGION.
KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. SNOW SHOWERS MAY ARRIVE
TOWARDS 00Z THIS EVENING.
KBDL TERMINAL...MODERATE CONFIDENCE IN TAF.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...
MONDAY INTO TUESDAY...MODERATE CONFIDENCE. EXPECT MOSTLY
VFR...ISOLATED MVFR ALONG THE MASS EAST COASTLINE IN RAIN/SNOW
SHOWERS.
TUESDAY NIGHT INTO WEDNESDAY...MODERATE CONFIDENCE. CONDITIONS WILL
BE DETERIORATING AS HEAVY DOWNPOURS...ISO THUNDER AND GUSTY SOUTHERLY
WINDS MOVE INTO THE REGION BY WEDNESDAY. COULD SEE MVFR TO IFR
CONDITIONS IN CIGS AND VSBYS.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT TERM /TODAY THROUGH SUNDAY/...HIGH CONFIDENCE.
HIGH PRESSURE ACROSS QUEBEC WILL RESULT IN PERSISTENT NORTHEAST
WINDS ACROSS THE WATERS THROUGH THE WEEKEND. WIND GUSTS UP TO 20
KNOTS WITH SEAS BETWEEN 2 AND 4 FEET ARE EXPECTED FOR MOST
WATERS...SO NO HEADLINES PLANNED. THERE IS A LOW PROBABILITY THAT A
BRIEF SURGE OF NORTHEAST WIND GUSTS NEAR 25 KNOTS WITH MARGINAL 5
FOOT SEAS COULD AFFECT OUR NORTHERN WATERS LATE TONIGHT INTO SUN
MORNING...BUT NOT CONFIDENT ENOUGH TO ISSUE ANY HEADLINES AT THIS
POINT.
OUTLOOK...SUNDAY NIGHT INTO WEDNESDAY...MODERATE TO HIGH
CONFIDENCE.
SUNDAY INTO MONDAY. CONTINUOUS NORTHEAST FLOW WILL KEEP SEAS CHOPPY.
LINGERING NORTHEAST SWELL MAY BUMP SEAS ABOVE 5FT ESP ACROSS THE
NORTHEASTERN WATERS. SCA MAY BE NEEDED...BUT LOWER CONFIDENCE.
TUESDAY INTO WEDNESDAY...NE WINDS WILL INCREASE...GUSTING TO 30 KT
TUE THEN SHIFT TO SE GUSTING TO 30-35 KT WED...HIGHEST ON THE OUTER
WATERS. SEAS BUILD UP TO 7-11 FT BY WED. GALES WILL BE NEEDED.
&&
.TIDES/COASTAL FLOODING...
HIGH ASTRONOMICAL TIDES WILL OCCUR TUESDAY THROUGH THURSDAY. BREAKING
IT DOWN...ON TUESDAY HIGH TIDE AT BOSTON WILL BE 11.6 FT. THERE WILL
BE ONSHORE FLOW DURING THIS HIGH TIDE ALLOWING FOR MINOR SPLASHOVER.
IF WIND GUSTS INCREASE THEN COULD POSSIBLE SEE MINOR COASTAL
FLOODING.
ON WEDNESDAY...WINDS WILL SWITCH TO A MORE SOUTHEASTERLY FLOW DURING
THE DAY AND INCREASE QUICKLY FROM APPROACHING SYSTEM AND DESCENT
PRESSURE FALLS. WEDNESDAY AFTERNOON HIGH TIDE IN BOSTON IS 11.7 FT
AND WITH ANY STRENGTH ON THE EASTERLY WIND FLOW WILL PUSH THE TIDE
OVER. RIGHT NOW BELIEVE MINOR COASTAL FLOODING IS POSSIBLE ALONG THE
EAST COASTLINE. HOWEVER WEDNESDAY EVENING...THE WIND GOES IN A MORE
SOUTHERLY DIRECTION AND HIGH TIDE IN PROVIDENCE WILL BE 5.2 FT. 925
MB LLJ STRENGTHENS TO 50-60 KTS WHICH COULD PUSH A DESCENT SURGE UP
ALONG THE SOUTH COAST DURING THE TIME OF HIGH TIDE. THINKING THAT
MINOR COASTAL FLOODING COULD OCCUR BUT CANNOT RULE OUT MODERATE
ALONG THE SOUTH COAST...ESP IF LLJ STRENGTHENS EVEN MORE.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...FRANK/DUNTEN
NEAR TERM...FRANK/DUNTEN/RLG
SHORT TERM...FRANK
LONG TERM...DUNTEN
AVIATION...FRANK/DUNTEN
MARINE...FRANK/DUNTEN
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
353 AM EST SAT DEC 20 2014
.DISCUSSION...
CURRENTLY...
...INCREASING CHANCE FOR SHOWERS/STORMS LATE SUNDAY INTO WED...
BROAD HI PRES RIDGE BLANKETING THE SW ATLC WITH A WEAK COLD FRONT
OVER THE GOMEX. EVENING SOUNDINGS SHOW INCREASING MOISTURE ACRS THE
PANHANDLE ASSOCD WITH THE FRONT WITH PWAT VALUES CREEPING ABV 1.0".
OVER CENTRAL FL...KTBW SOUNDING MEASURED PWATS ARND 0.8"...THOUGH
MOST OF THIS IS IN THE FORM OF A MID/UPR LVL DECK AS AVG DEWPOINT
DEPRESSIONS THRU THE H100-H70 LYR REMAIN BTWN 10-15C. TO THE S...
KMFL SHOWS SUBSTANTIAL DRY AIR THRU THE H85-H50 LYR. RUC ANALYSIS
INDICATES UPSTREAM H100-H70 MEAN RH VALUES INCREASING FROM 40PCT
OVER S FL TO AOA 80PCT OVER THE YUCATAN CHANNEL...AND H85-H50 VALUES
INCREASING FROM ARND 40PCT OVER CENTRAL FL TO AOA 60PCT OVER THE
CENTRAL GOMEX.
ALOFT...A 90-110KT JET STREAK EXTENDING FROM THE BAJA PENINSULA TO
BERMUDA HAS A STRONG ZONAL ORIENTATION THAT IS GENERATING A DEEP
W/SW FLOW THRU THE H85-H30 LYR. MODERATELY COOL AIR AIR IN PLACE
WITH H50 TEMPS ARND -10C. SIG VORT MAXES ARE ALMOST NONEXISTENT THRU
THE H85-H30 LYR...WHILE THE OMEGA FIELDS THRU THE SAME LYR ARE
BASICALLY NEUTRAL. H70-H50 LAPSE RATES ARND 6.0C/KM ARE NOT
ESPECIALLY IMPRESSIVE...ESPECIALLY GIVEN THE H85-H70 LAPSE RATES ARE
BLO 5.0C/KM.
TODAY-TONIGHT...
THE RIDGE AXIS WILL BE THE PRIMARY WX FEATURE FOR CENTRAL FL AS THE
JET OVER THE SRN TIER STATES DRAGS THE WEAK COLD FRONT INTO THE FL
PANHANDLE. HOWEVER...THE ZONAL ORIENTATION OF THE JET WILL PREVENT
THE FRONT FROM PUSHING MUCH FURTHER S THAN THE NECK OF THE PENINSULA
BY DAYBREAK SUN.
RUC40 ANALYSIS SHOWS A TIGHT ISENTROPIC GRADIENT THRU THE 300K-315K
LYR THAT WILL EVENTUALLY SET THE STAGE FOR THE NEXT RAIN EVENT ACRS
CENTRAL FL AS THE MID LVL WINDS REMAIN OUT OF THE W/SW. HOWEVER...
THE DRY AIR OVER THE CENTRAL/SRN PENINSULA WILL NEED TO MODIFY
BEFORE ANY MEASURABLE PRECIP OCCURS...ESPECIALLY GIVEN THE LACK OF
ANY SIG DYNAMIC/THERMODYNAMIC SUPPORT.
FORECAST WILL REMAIN DRY. TEMPS WILL BE A FEW DEG WARMER THAN FRI
DUE TO WARM AIR ADVECTION THAT WILL ACCOMPANY THE S/SW FLOW THAT HAS
DVLPD THRU THE H100-H85 LYR. AFTN MAXES IN THE M/U70S WILL BE 3-7F
DEG ABV AVG. OVERNIGHT MINS IN THE M/U50S EXCEPT L60S ALONG THE
IMMEDIATE COAST...5-10F ABV AVG.
SUN-WED...MODELS CONTINUE TO SHOW A QUITE CLOUDY PERIOD WITH
DAILY RAIN CHANCES.
SUN-MON...A TROUGH WITH FAIRLY DECENT SOUTHERN EXTENT INTO THE
WESTERN GULF ON SUNDAY WILL DAMPEN OUT AS IT MOVES ACROSS THE
SOUTHEAST STATES SUNDAY NIGHT/MON. THERE WILL INITIALLY BE A MID
LEVEL DRY LAYER SUNDAY BUT INCREASING SOUTH/SOUTHWEST FLOW IN THE
LOW/MID LEVELS WILL MOISTEN UP THE ATMOSPHERE CONSIDERABLY BY LATE
DAY AND SUNDAY NIGHT. GFS/ECMWF DIFFER A BIT WITH HIGHEST PRECIP
COVERAGE. THE GFS SHOWS HIGH POPS AREAWIDE SUNDAY NIGHT INTO MON.
THE ECMWF CONCENTRATES THE HIGHEST COVERAGE ACROSS NORTHERN
SECTIONS...WHICH IS MORE TYPICAL FOR THIS TIME OF THE YEAR AND
WHERE THE GREATEST ISENTROPIC LIFT IS SHOWN. THEREFORE HAVE NOT
GONE WITH THE 60-70 POPS INDICATED BY THE GFS...EXCEPT ACROSS THE
FAR NORTH. THINK THAT PRECIP WILL MAINLY BE SHOWERY BUT CANNOT
RULE OUT SOME ELEVATED INSTABILITY AND ISOLATED THUNDER.
TUE-WED...THE MODELS ONLY SHOW SLIGHT CHANGES WITH THE NEXT
TROUGH WHICH WILL BE HIGHLY AMPLIFIED AND DIG WELL INTO THE GULF
OF MEXICO. A PRE FRONTAL BAND OF SHOWERS/STORMS IS EXPECTED TO
PUSH INTO NORTHERN SECTIONS TUE NIGHT AND SOUTHERN SECTIONS WED.
THIS IS SLIGHTLY SLOWER THAN PREVIOUS THINKING. THE DEEPENING
SURFACE LOW ASSOCIATED WITH THIS SYSTEM WILL BE LIFTING INTO THE
OHIO VALLEY AS THE BAND OF CONVECTION REACHES THE LOCAL AREA.
STILL THE LOW LEVEL WIND FIELDS ARE PROGGED TO BE 40-45 KNOTS. SO
FAST MOVING STORMS ARE EXPECTED WHICH MAY BRING A CHANCE FOR
DAMAGING WIND GUSTS.
HAVE GONE WITH CHANCE POPS ON TUE DUE TO THE MOIST SOUTHERLY FLOW
AND KEPT MENTION OF THUNDER DUE TO A POTENTIAL FOR SOME
DIVERGENCE ALOFT IN THE PRESENCE OF MODEST SURFACE HEATING.
GREATEST DYNAMICS ARE INDICATED TUE NIGHT INTO WED SO HAVE GONE
WITH A PERIOD OF LIKELY POPS FOR THE ENTIRE AREA THEN.
CHRISTMAS THRU NEXT SAT...
COOL/DRY AIR ADVECTION INDICATED ON CHRISTMAS DAY. MORNING LOWS IN
THE UPPER 40S TO LOWER 50S EXPECTED WITH DAYTIME HIGHS IN THE
LOWER TO MID 60S. HIGH PRESSURE RIDGE OVER THE AREA ON FRI WILL
CONTINUE THE DRY WEATHER AND AFTER A COOL MORNING IN THE MID 40S
TO LOWER 50S...A SLOW MODERATION OF TEMPERATURES TO THE UPPER 60S
AND LOWER 70S IS EXPECTED. THE NEXT APPROACHING FRONT SHOULD
WEAKEN AS IT RUNS INTO WEAKENING SURFACE RIDGE...SO WILL KEEP THE
FORECAST DRY ON SAT AS TEMPERATURES MODIFY TO NORMAL OR A LITTLE
ABOVE.
&&
.AVIATION...
SFC WINDS: THRU 20/15Z...VRBL AOB 3KTS. BTWN 20/15Z-20/18Z...S BTWN
4-7KTS. WNDSHFT TO E/SE 5-8KTS AFT 20/18Z...BTWN 20/18Z-20/20Z CSTL
SITES...BTWN 20/21Z-20/23Z INTERIOR SITES. AFT 21/00Z...VRBL AOB
3KTS.
VSBYS: THRU 20/13Z...LCL MVFR/BRIEF IFR IN BR. AFT 20/13Z VFR ALL
SITES.
CIGS: THRU 20/13Z...AREAS AOA FL120 N OF KTIX-KISM...LCL MVFR CIGS
BTWN FL020-030 CSTL SITES S OF KMLB. AFT 20/13Z...VFR ALL SITES...
PREVAILING CIGS AOA FL120 N OF KMLB-KISM...BCMG FL100-120 AFT 20/18Z.
&&
.MARINE...
TODAY-TONIGHT...A WEAK AND BROAD HI PRES RIDGE BLANKETING THE REGION
FROM THE CAROLINA COAST TO THE BAHAMA BANK WILL GENERATE A LIGHT TO
GENTLE SRLY BREEZE ACRS THE LCL ATLC THRU EARLY AFTN. WINDS WILL
SHIFT TO THE E/SE BY MID AFTN AS THE SEABREEZE FORMS...BUT THE WEAK
PGRAD WILL NOT SUPPORT ANYTHING GREATER THAN 10KTS. WINDS WILL
CONTINUE E/NE OVERNIGHT AS A WEAK FRONTAL BOUNDARY DRIFTS INTO THE
FL PANHANDLE. SEAS AOB 2FT.
SUNDAY...SOUTHEAST FLOW STILL INDICATED AT 10 KNOTS OR LESS. THE
DAY LOOKS QUITE CLOUDY WITH A CHANCE OF SHOWERS LATE IN THE DAY
ESPECIALLY CANAVERAL NORTHWARD.
MON-WED...WINDS WILL BECOME SOUTH/SOUTHWEST AND INCREASE AHEAD OF
A COLD FRONT ESPECIALLY TUE-WED. EXPECT A CHANCE FOR SHOWERS AND
SLIGHT CHANCE FOR STORMS IN A MOIST AIR MASS MON/TUE...BUT A
PERIOD OF STRONG STORMS IS EXPECTED LATE TUE NIGHT AND INTO WED.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 73 59 74 64 / 10 10 30 70
MCO 76 59 77 64 / 0 10 20 50
MLB 77 62 77 66 / 0 10 20 50
VRB 77 61 77 64 / 0 10 10 40
LEE 75 58 76 63 / 0 10 30 70
SFB 76 59 76 64 / 0 10 30 60
ORL 76 60 76 64 / 0 10 30 60
FPR 77 60 77 65 / 0 10 10 30
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM...BRAGAW
LONG TERM....LASCODY
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
244 PM EST SAT DEC 20 2014
.SYNOPSIS...
A FRONTAL ZONE WILL REMAIN NEAR THE SOUTHEAST COAST
THROUGH TUESDAY. A SERIES OF LOW PRESSURE SYSTEMS WILL MOVE
NORTHEASTWARD ALONG THE FRONT. A STRONG COLD FRONT APPROACHING
FROM THE WEST WILL MOVE THROUGH THE FORECAST AREA WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
RAIN HAS ALMOST CLEARED THE FORECAST AREA WITH SOME LINGERING RAIN
OVER THE EASTERN MIDLANDS BUT THIS TOO SHOULD SHIFT OUT BY 2 PM.
TEMPERATURES HAVE NOT MOVED MUCH TODAY DUE TO EXTENSIVE CLOUDS AND
LIGHT RAIN BUT MAY RISE A DEGREE OR TWO BEFORE SUNSET NOW THAT THE
RAIN HAS CLEARED. LOW CLOUDS EXTEND WELL BACK INTO ALABAMA AND
WITH MODEL TIME HEIGHTS AND CROSS SECTIONS SHOWING SIGNIFICANT
MOISTURE IN THE LOWER LEVELS DO NOT THINK THE LOW CLOUDS WILL
BREAK OVERNIGHT. WITH THE FORECAST AREA IN THE WAKE OF THE
DEPARTING SHORTWAVE TROUGH AND THEREFORE LACK OF UPWARD VERTICAL
MOTION DO NOT THINK THERE WILL BE SIGNIFICANT DRIZZLE OVERNIGHT
BUT DO THINK THERE WILL BE AREAS OF FOG THAT DEVELOPS AND POSSIBLY
SOME DENSE FOG IN TYPICAL LOW LYING AREAS. OVERNIGHT LOWS TONIGHT
SHOULD FALL INTO THE MID 30S ACROSS THE FORECAST AREA.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
THE MID/UPPER FLOW WILL BECOME INCREASINGLY SOUTHWEST DURING THE
DAY ON SUNDAY INTO SUNDAY NIGHT AS A S/W TROUGH MOVES INTO THE MS
VALLEY. MODEL TIME SECTIONS SHOW INCREASING LOW LEVEL MOISTURE AND
ISENTROPIC LIFT THROUGH THE PERIOD AS WEAK LOW PRESSURE DEVELOPS
IN THE GULF AND MOVES NORTHEAST ACROSS FLORIDA AND OFF THE
SOUTHEAST COAST. DURING THE PERIOD...PRECIPIATION AMOUNTS LOOK TO
BE LESS THAN ONE QUARTER INCH AS THE LIGHT RAIN/DRIZZLE IS
EXPECTED. WILL CONTINUE WITH SOME PATCHY FOG SUNDAY MORNING WITH
POPS AROUND 10 PERCENT OR LESS. HOWEVER...THROUGH THE AFTERNOON
WITH INCREASING ISENTROPIC LIFT FROM S TO N EXPECT A GRADUAL
INCREASE IN POPS. POPS GO FROM SLIGHT CHANCE SUNDAY TO CATEGORICAL
BY LATER SUNDAY NIGHT. AS FOR TEMPERATURES...EXPECT LITTLE DIURNAL
RANGE GIVEN CLOUD COVER AND PRECIPITATION POTENTIAL. HAVE TRENDED
TOWARD JUST BELOW CONSENSUS FOR HIGHS AND JUST ABOVE FOR LOWS.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
A MORE VIGOROUS S/W WILL DIG A DEEP TROUGH ACROSS THE EASTERN HALF
OF THE COUNTRY BY MID WEEK AS MID LEVEL LOW CLOSES OFF ACROSS THE
UPPER PLAINS/UPPER MIDWEST. MOISTURE ACROSS THE REGION WILL REMAIN
RATHER HIGH THROUGH MIDWEEK WITH PW VALUES INCREASING TO OVER 1.5
INCHES BY LATE TUESDAY NIGHT/INTO WEDNESDAY. AHEAD OF THIS SYSTEM
A WEDGE WILL DEVELOP ACROSS THE AREA ON MONDAY AND MODELS INDICATE
THIS FEATURE HOLDING INTO TUESDAY. HAVE TRENDED WITH LOWER
TEMPERATURES THROUGH THE PERIOD AS ECMWF/GFS/NAM INDICATE NE LOW
LEVEL FLOW AND VERY STABLE AIRMASS IN PLACES OVER THE REGION.
HOWEVER...BY LATE TUESDAY AFTERNOON/TUESDAY NIGHT BOTH ECMWF AND
GFS LIFT THE WARM FRONT NORTHWARD ACROSS THE AREA. TEMPERATURES
WILL LIKELY RISE SLOWLY TUESDAY NIGHT AS LOW LEVEL FLOW SHIFTS
FROM NE AND E TO A MORE SOUTHERLY DIRECTION. THE GFS AND ECMWF
MODELS HAVE CONTINUED WITH THE TREND OF THE SLOWER COLD FRONTAL
PASSAGE ON WEDNESDAY. THE AREA WILL REMAIN UNDER ISENTROPIC LIFT
THROUGH MUCH OF THE PERIOD FROM MONDAY INTO EARLY WEDNESDAY WITH
AN INCREASING WIND FIELD TUESDAY NIGHT INTO WEDNESDAY. THE GFS
SHOWS A 50 TO 60 KT H8 JET ASSOCIATED WITH THE SYSTEM EARLY
WEDNESDAY. WITH THE DELAY OF THE FRONTAL PASSAGE AND AREA BECOMING
INCREASINGLY UNSTABLE BY WEDNESDAY HAVE CONTINUED THE MENTION OF
THUNDERSTORMS IN THE FORECAST. ALSO EXPECT INCREASING SURFACE
WINDS WITH TIGHT PRESSURE GRADIENT AND STRONG LOW LEVEL WINDS ON
WEDNESDAY.
THE INCREASING SHEAR AND POTENTIAL FOR SUFFICIENT INSTABILITY
INDICATES A POSSIBILITY OF STRONG/SEVERE THUNDERSTORMS.
EXPECT A DIMINISHED SHOWER CHANCE WEDNESDAY NIGHT BEHIND THE
FRONT WITH BREEZY CONDITIONS. THE MODELS HAVE BEEN CONSISTENT
SHOWING A DRY WEST FLOW BETWEEN HIGH PRESSURE NEAR THE GULF COAST
AND LOW PRESSURE LIFTING NORTH OF THE GREAT LAKE REGION FOR
CHRISTMAS DAY. BREEZY CONDITIONS MAY CONTINUE DURING THE DAY...BUT
THE MODEL TREND HAS BEEN TO SHOW THE RIDGE FARTHER NORTHWARD WITH
LESS OF A PRESSURE GRADIENT IN THE FORECAST AREA.
MOISTURE MAY INCREASE AHEAD OF ANOTHER COLD FRONT APPROACHING
FRIDAY NIGHT INTO SATURDAY. HAVE CONTINUED THE MENTION OF A SMALL
POP FRIDAY NIGHT AND SATURDAY. EXPECT TEMPERATURES TO BE COOLER
THAN NORMAL MONDAY AND TUESDAY...ABOVE NORMAL WEDNESDAY AND THEN
RETURNING TO MORE NORMAL TEMPERATURES FOR THE REMAINDER OF THE
PERIOD.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
MVFR/IFR CIG RESTRICTIONS EXPECTED THROUGH MUCH OF THE 24 HOUR
FORECAST PERIOD.
REGIONAL RADAR SHOWING THE RAIN ASSOCIATED WITH THE PASSING
SHORTWAVE TROUGH HAS SHIFTED EAST OF THE TERMINALS AND DO NOT
EXPECT ANY ADDITIONAL RAIN. SUBSIDENCE BEHIND THE SHORTWAVE HAS
STRENGTHENED THE INVERSION AND LOW LEVEL MOISTURE TRAPPED BELOW IT
SO AM EXPECTING THE MVFR/IFR CIGS TO CONTINUE THROUGH THE FORECAST
PERIOD. HRRR GUIDANCE HAS BEEN TO OPTIMISTIC WITH CIGS THUS FAR
TODAY AND MET GUIDANCE HAS BEEN DOING WELL WITH THE LOW CIGS SO
HAVE LEANED TOWARD THAT GUIDANCE AND THE LAV GUIDANCE LOWERING
CIGS TO IFR ALL TERMINALS AFTER 04Z WITH POSSIBLE LIFR CIGS
OGB/AGS/DNL. VSBYS ALSO LIKELY TO DROP INTO MVFR AND POSSIBLY IFR
04Z-12Z TIME FRAME. SOME IMPROVEMENT IS EXPECTED AFTER 13Z BUT LOW
CONFIDENCE THAT VFR CONDITIONS WILL RETURN.
EXTENDED AVIATION OUTLOOK...WIDESPREAD LOW CLOUDS AND
PRECIPITATION EXPECTED LATE SUNDAY NIGHT INTO MONDAY WITH ANOTHER
GULF COAST SYSTEM CROSSING THE REGION. YET ANOTHER SYSTEM WILL
AFFECT THE AREA TUESDAY NIGHT BRINGING POSSIBLE RESTRICTIONS WITH
WINDY CONDITIONS EXPECTED WEDNESDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
77
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
137 PM EST SAT DEC 20 2014
.SYNOPSIS...
A FRONTAL ZONE WILL REMAIN NEAR THE SOUTHEAST COAST
THROUGH TUESDAY. A SERIES OF LOW PRESSURE SYSTEMS WILL MOVE
NORTHEASTWARD ALONG THE FRONT. A STRONG COLD FRONT APPROACHING
FROM THE WEST WILL MOVE THROUGH THE FORECAST AREA WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
RAIN HAS ALMOST CLEARED THE FORECAST AREA WITH SOME LINGERING RAIN
OVER THE EASTERN MIDLANDS BUT THIS TOO SHOULD SHIFT OUT BY 2 PM.
TEMPERATURES HAVE NOT MOVED MUCH TODAY DUE TO EXTENSIVE CLOUDS AND
LIGHT RAIN BUT MAY RISE A DEGREE OR TWO BEFORE SUNSET NOW THAT THE
RAIN HAS CLEARED. LOW CLOUDS EXTEND WELL BACK INTO ALABAMA AND
WITH MODEL TIME HEIGHTS AND CROSS SECTIONS SHOWING SIGNIFICANT
MOISTURE IN THE LOWER LEVELS DO NOT THINK THE LOW CLOUDS WILL
BREAK OVERNIGHT. WITH THE FORECAST AREA IN THE WAKE OF THE
DEPARTING SHORTWAVE TROUGH AND THEREFORE LACK OF UPWARD VERTICAL
MOTION DO NOT THINK THERE WILL BE SIGNIFICANT DRIZZLE OVERNIGHT
BUT DO THINK THERE WILL BE AREAS OF FOG THAT DEVELOPS AND POSSIBLY
SOME DENSE FOG IN TYPICAL LOW LYING AREAS. OVERNIGHT LOWS TONIGHT
SHOULD FALL INTO THE MID 30S ACROSS THE FORECAST AREA.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
HIGH LOW-LEVEL MOISTURE WILL CONTINUE THROUGH TONIGHT. THERE MAY
BE AREAS OF FOG AS INDICATED BY THE GFS MOS. LITTLE TEMPERATURE
RECOVERY SHOULD OCCUR TODAY BECAUSE OF CLOUDINESS. THE HIGH
TEMPERATURE GUIDANCE IS LIKELY TOO WARM. LEANED TOWARD THE MORE
CONSISTENT GFS MOS FOR THE TEMPERATURE TONIGHT.
WEAK ISENTROPIC LIFT SUPPORTS A RAIN CHANCE SUNDAY MAINLY LATE AS
MOISTURE BECOMES DEEPER AHEAD OF ANOTHER MID-LEVEL SHORTWAVE
TROUGH. THE GUIDANCE CONSENSUS SUPPORTS POPS OF 20 TO 30 PERCENT
FOR MAINLY LATE IN THE DAY. THE MODELS ARE CONSISTENT DISPLAYING
SIGNIFICANT MOISTURE AND ISENTROPIC LIFT SUNDAY NIGHT INTO MONDAY
ESPECIALLY IN THE SOUTHEAST PART OF THE FORECAST AREA. THE MODELS
INDICATE MOISTURE BECOMING SHALLOW LATE MONDAY BEHIND THE
ASSOCIATED MID-LEVEL SHORTWAVE TROUGH. USED THE GUIDANCE CONSENSUS
FOR THE POP FORECAST. THE GUIDANCE HIGH TEMPERATURES ARE LIKELY
TOO WARM BECAUSE OF CLOUDINESS AND A LOW-LEVEL NORTHEAST FLOW. THE
GUIDANCE LOW TEMPERATURE WERE CLOSE. THE MODELS HAVE BEEN
CONSISTENT INDICATING ALL-LIQUID PRECIPITATION.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
HIGH MOISTURE SHOULD CONTINUE MONDAY NIGHT THROUGH TUESDAY AHEAD
OF A WARM FRONT AND DEEPENING UPPER-LEVEL TROUGH. THE GFS AND
ECMWF MODELS HAVE TRENDED SLOWER WITH THE PASSAGE OF A STRONG
COLD FRONT AND NOW DISPLAY FRONTAL PASSAGE WEDNESDAY. THE WARM
FRONT MAY LIFT NORTHWARD AHEAD OF THE COLD FRONT.
IF THE FORECAST AREA GETS INTO THE WARM SECTOR THERE MAY BE
ENOUGH INSTABILITY FOR THUNDERSTORMS AHEAD OF THE COLD FRONT TUESDAY
NIGHT OR WEDNESDAY. THE GFS AND ECMWF DISPLAY H85 WINDS OF 40 TO
60 KNOTS. THE SHEAR AND POTENTIAL FOR SUFFICIENT INSTABILITY
INDICATES A POSSIBILITY OF SEVERE THUNDERSTORMS.
EXPECT A DIMINISHED SHOWER CHANCE WEDNESDAY NIGHT BEHIND THE
FRONT WITH BREEZY CONDITIONS. THE MODELS HAVE BEEN CONSISTENT
SHOWING A DRY WEST FLOW BETWEEN HIGH PRESSURE NEAR THE GULF COAST
AND LOW PRESSURE LIFTING NORTH OF THE GREAT LAKE REGION FOR
CHRISTMAS DAY. BREEZY CONDITIONS MAY CONTINUE DURING THE DAY...BUT
THE MODEL TREND HAS BEEN TO SHOW THE RIDGE FARTHER NORTHWARD WITH
LESS OF A PRESSURE GRADIENT IN THE FORECAST AREA.
MOISTURE MAY INCREASE AHEAD OF ANOTHER COLD FRONT APPROACHING
FRIDAY. THE GFS SHOWS LESS MOISTURE COMPARED TO THE ECMWF. THE
ECMWF KEEPS MUCH OF THE FORCING ASSOCIATED WITH THE FRONT WEST OF
THE FORECAST AREA THROUGH FRIDAY. THE GFS...ECMWF...AND EKD MOS
POPS ARE JUST 10 TO 20 PERCENT.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
MVFR/IFR CIG RESTRICTIONS EXPECTED THROUGH MUCH OF THE 24 HOUR
FORECAST PERIOD.
REGIONAL RADAR SHOWING THE RAIN ASSOCIATED WITH THE PASSING
SHORTWAVE TROUGH HAS SHIFTED EAST OF THE TERMINALS AND DO NOT
EXPECT ANY ADDITIONAL RAIN. SUBSIDENCE BEHIND THE SHORTWAVE HAS
STRENGTHENED THE INVERSION AND LOW LEVEL MOISTURE TRAPPED BELOW IT
SO AM EXPECTING THE MVFR/IFR CIGS TO CONTINUE THROUGH THE FORECAST
PERIOD. HRRR GUIDANCE HAS BEEN TO OPTIMISTIC WITH CIGS THUS FAR
TODAY AND MET GUIDANCE HAS BEEN DOING WELL WITH THE LOW CIGS SO
HAVE LEANED TOWARD THAT GUIDANCE AND THE LAV GUIDANCE LOWERING
CIGS TO IFR ALL TERMINALS AFTER 04Z WITH POSSIBLE LIFR CIGS
OGB/AGS/DNL. VSBYS ALSO LIKELY TO DROP INTO MVFR AND POSSIBLY IFR
04Z-12Z TIME FRAME. SOME IMPROVEMENT IS EXPECTED AFTER 13Z BUT LOW
CONFIDENCE THAT VFR CONDITIONS WILL RETURN.
EXTENDED AVIATION OUTLOOK...WIDESPREAD LOW CLOUDS AND
PRECIPITATION EXPECTED LATE SUNDAY NIGHT INTO MONDAY WITH ANOTHER
GULF COAST SYSTEM CROSSING THE REGION. YET ANOTHER SYSTEM WILL
AFFECT THE AREA TUESDAY NIGHT BRINGING POSSIBLE RESTRICTIONS WITH
WINDY CONDITIONS EXPECTED WEDNESDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
NEAR TERM...HC
AVIATION...HC
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
913 PM CST SUN DEC 21 2014
.SHORT TERM...
246 PM CST
THROUGH TUESDAY...
TONIGHT THROUGH TUESDAY...
BROAD SFC RIDGE HAS BECOME CENTERED OVER THE NORTHEAST CONUS...AND
CONTINUES TO SLOWLY DRIFT EAST/NORTHEAST. THE GRADIENT ACROSS THE
GREAT LAKES HAS REMAINED LIGHT THIS AFTN...WITH A MAINLY SOUTHERLY
FLOW. CLOUDS REMAIN LOCKED IN ACROSS THE FORECAST AREA...WITH SOME
CLEARING JUST SOUTHEAST OF THE CWFA IN CENTRAL/NORTHERN IN. SFC
TEMPS HAVE BEEN ABLE TO WARM TO THE MID/UPR 30S...WITH DEW PTS
HOVERING AROUND 30-33 DEG. MOST THE EVENING WILL REMAIN DRY...WITH
THE WEAK MID-LVL WAVE SLIDING NORTHEAST ACROSS IOWA/WISC WITH SOME
LGT SNOW...OTHERWISE MOST OF THE FORECAST AREA SHUD REMAIN DRY THRU
THE OVERNIGHT PERIOD.
500MB VORT BEGINS TO LIFT NORTHEAST FROM THE CENTRAL PLAINS BEFORE
DAYBREAK MON...PUSHING THE MOIST CHANNEL FURTHER EAST ACROSS THE
FORECAST AREA. WITH SOUNDINGS SUGGESTING A WARM WEDGE DEVELOPING
ALOFT...P-TYPE COULD BE A CHALLENGE ARND DAYBREAK. GUIDANCE WOULD
SUGGEST TEMPS COULD BE WARM ENOUGH TO LIMIT PRECIP TO LGT
RAIN...WITH NEAR SFC TEMPS HOLDING ARND THE FREEZING MARK...SO HAVE
CONTINUED THE MENTION OF FZRA MAINLY SOUTH OF ROCKFORD. CLOSER TO
ROCKFORD THE THERMAL PROFILE IS A LITTLE MORE TRICKY AND COULD ALLOW
SOME LGT SNOW/SLEET AT THE ONSET CHANGING TO LGT RA/FZRA BEFORE
MIDDAY. THROUGHOUT THE AFTN TEMPS WILL STEADILY WARM...NEARING 40
DEG IN MOST LOCATIONS AS WARM/MOIST AIR CONTINUES TO ADVECT NORTH
ACROSS THE CWFA. MOST GUIDANCE INDICATES LGT RAIN WILL PERSIST THRU
THE AFTN/EVE HOURS...WITH THE DRY WEDGE NOT ARRIVING UNTIL CLOSER TO
DAYBREAK TUE. LOCAL SOLUTION SUGGESTS SLIGHTLY EARLIER WITH BRINGING
A TEMPORARY END TO THE PRECIP...JUST AFT MIDNIGHT MON NGT.
TEMPS OVERNIGHT WILL REMAIN MILD IN THE UPR 30S/NEAR 40. WITH THE
TROUGH TAKING ON A NEGATIVE TILT MIDDAY TUE...THE SFC LOW WILL BE
WRAPPED UP ACROSS CENTRAL WISC. GUIDANCE HAS BOUNCED AROUND POSSIBLY
KEEPING EITHER DRY/LOW CHC POPS OVER NORTHERN IL/NORTHWEST IN
TUE/TUE AFTN...BUT HAVE OPTED TO HOLD ONTO A SLT CHC OF RAIN. WITH
WARM AIR CONTINUING TO ADVECT NORTH...SFC TEMPS COULD PUSH INTO THE
MID/UPR 40S WITH A FEW LOCATIONS IN THE SOUTHEAST REACHING 50 DEG.
BY TUE EVENING THE TROUGH AXIS IS PROGGED TO EJECT ANOTHER SFC LOW
ACROSS THE GULF STATES...THEN QUICKLY LIFT NORTH ACROSS THE TENN
VALLEY LATE TUE NGT. MOISTURE WILL FILL BACK IN ACROSS THE FORECAST
AREA TUE NGT...WITH RAIN BECOMING MIXED WITH SNOW OVERNIGHT. TEMPS
WILL SLOWLY COOL...SO THE PERIOD OF RAIN/SNOW MIX COULD LINGER
AWHILE.
BEACHLER
&&
.LONG TERM...
246 PM CST
WEDNESDAY THROUGH SUNDAY...
MID-WEEK ENSEMBLES CONTINUE TO PROG A SLIGHT STRENGTHENING TO THE
DOWNSTREAM RIDGE OVER THE CANADIAN MARITIME...WHICH WILL LIMIT HOW
FAR EAST THE SECONDARY LOW WILL PROGRESS. OPERATIONAL SOLUTIONS
CONTINUE TO LIFT THE STRENGTHENING LOW NORTH ACROSS THE OHIO VALLEY
WED AFTN...AND QUICKLY NORTH OF LAKE HURON BY LATE WED NGT. WRAP
AROUND MOISTURE AND COOLER AIR WILL BRING SOME LGT SNOW TO NORTHERN
IL WED.
FOR CHRISTMAS DAY THE DOWNSTREAM RIDGE WILL BEGIN TO
WEAKEN...ALLOWING THE MID-LVL TROUGH TO BECOME PROGRESSIVE AND PUSH
EAST. THIS SHUD BRING AN END TO THE LGT SNOW/FLURRIES BY DAYBREAK.
TEMPS SHUD RETURN TO THE MID/UPR 30S...ALONG WITH PERHAPS SOME
BREAKS IN THE CLOUD COVER BY THE AFTN. MID-LVL HEIGHTS SHUD START TO
INCREASE THUR NGT/FRI...HOWEVER THIS LOOKS TO BE SHORT-LIVED AS YET
ANOTHER TROUGH IS PROGGED TO DIG SOUTH FROM THE CANADIAN ROCKIES
INTO THE NORTHERN PLAINS. THE STRONGER PUSH OF COLDER AIR LOOKS TO
ARRIVE SAT...ALTHOUGH THIS MAY ONLY BE A SHORT DURATION WITH THE
SEMI-ZONAL PATTERN SETTING UP FOR THE SECOND HALF OF THE WEEKEND.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* PRIMARILY VFR OR MVFR CIGS THROUGH MONDAY MORNING...LIKELY
LOWERING TO IFR MONDAY AFTERNOON AND POSSIBLY LIFR MONDAY
EVENING
* RAIN DEVELOPS AROUND MIDDAY MONDAY AND CONTINUES THROUGH MONDAY
EVENING
IZZI
//DISCUSSION...UPDATED 00Z...
ANOTHER DAY OF STRATUS ACROSS THE REGION. SOUTHERN FLANK OF
STRATUS HAD BEEN LIFTING NORTH TOWARD I-80 BUT APPEARS TO BE
RECENTLY REDEVELOPING. CONFIDENCE IN CIGS TONIGHT IS LOW WITH MANY
MODELS SUGGESTING IMPROVEMENT TO VFR...THOUGH IN LIGHT OF RECENT
TRENDS HAVE OPTED TO RUN WITH MVFR WITH VERY LOW CONFIDENCE. RAIN
WILL LIKELY OVERSPREAD THE TERMINALS MIDDAY MONDAY AND CONTINUE
FAIRLY STEADILY INTO THE EVENING HOURS. CIGS/VSBY SHOULD FALL WITH
THE ONSET OF RAIN WITH IFR CONDITIONS LIKELY...PROBABLY LOWERING
TO LIFR MONDAY EVENING.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* LOW CONFIDENCE IN CIGS TONIGHT/MONDAY MORNING INCREASING TO LOW-
MEDIUM CONFIDENCE LATER MON AFTERNOON AND EVENING
* MEDIUM-HIGH CONFIDENCE IN GENERAL PRECIP TIMING
* HIGH CONFIDENCE IN REMAINING ELEMENTS
IZZI
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY...MVFR CIGS LIKELY. IFR CIGS POSSIBLE...MAINLY EARLY.
WEDNESDAY...MVFR CIGS LIKELY. CHANCE OF RA/SN.
THURSDAY...CHANCE OF MVFR CIGS...MAINLY EARLY.
FRIDAY...CHANCE OF MVFR CIGS. CHANCE OF -RA/-SN
SATURDAY...MVFR CIGS LIKELY. CHANCE OF FLURRIES.
IZZI
&&
.MARINE...
204 PM CST
SMALL CRAFT ADVISORY...KEPT THE CURRENT SMALL CRAFT AS IS AND
EXPANDED IT TWO ZONES SOUTH THROUGH CALUMET HARBOR. WAVES WILL
BECOME HAZARDOUS OVERNIGHT NORTH OF WILMETTE HARBOR AND THEN WINDS
AND WAVES WILL BECOME HAZARDOUS TOMORROW AFTERNOON. MARGINAL SMALL
CRAFT CONDITIONS ARE POSSIBLE ALONG THE INDIANA NEARSHORE WATERS AND
DO NOT HAVE ENOUGH CONFIDENCE TO ISSUE A SMALL CRAFT ADVISORY AT
THIS TIME.
HIGH PRESSURE IS OVER THE EAST COAST WHILE THE NEXT LOW IS OVER THE
NORTHERN PLAINS. SOUTH WINDS HAVE INCREASED TO 15-25 KT ACROSS THE
LAKE AND WILL CONTINUE TO INCREASE TO 30 KT THIS AFTERNOON. WINDS
BECOME SOUTHEAST TOMORROW AS THE LOW MOVES OVER THE EASTERN PLAINS
AND WEAKENS. THE LOW THEN WEAKENS OVER WISCONSIN TUESDAY AFTERNOON
THROUGH TUESDAY NIGHT. WINDS WEAKEN ACROSS THE LAKE MONDAY NIGHT AND
BECOME WEST TO NORTHWEST 10-15 KT TUESDAY NIGHT. A SECOND LOW FORMS
OVER THE SOUTHERN MISSISSIPPI VALLEY TUESDAY NIGHT AND QUICKLY
DEEPENS AS IT MOVES NORTH. GUIDANCE DIFFERS ON HOW FAR TO OUR EAST
THE LOW WILL PASS...BUT THINKING IT WILL BE OVER THE EASTERN GREAT
LAKES. GUIDANCE HAS ALSO BACKED OFF ON WIND SPEEDS BEHIND THE LOW
AND WILL ONLY CARRY OCCASIONAL GALES IN THE GLF AT THIS TIME. SO
HAVE WEST TO NORTHWEST WINDS INCREASING TO 30 KT WEDNESDAY NIGHT.
THE BEST WINDOW FOR GALES WOULD BE LATE WEDNESDAY NIGHT. THE LOW
THEN CONTINUES NORTHEAST INTO QUEBEC THURSDAY AND HAVE SOUTHWEST
WINDS DECREASING THURSDAY. ANOTHER LOW SLIDES ACROSS THE PLAINS
THURSDAY AFTERNOON AND WILL IMPACT THE LAKE FRIDAY. GUIDANCE
DIFFERS ON HOW STRONG THE LOW WILL BE WHEN IT MOVES OVER THE
LAKE...SO HAVE LOW CONFIDENCE IN THE FORECAST LATE NEXT WEEK.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 3 AM TUESDAY.
SMALL CRAFT ADVISORY...LMZ741-LMZ742...NOON MONDAY TO 3 AM
TUESDAY.
&&
$$
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[top]
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
908 PM CST Sun Dec 21 2014
.UPDATE...
ISSUED AT 904 PM CST SUN DEC 21 2014
Moisture channel satellite imagery depicts minor vort max near
Quincy moving to the northeast. Radar showing development of some
very light pcpn ahead of the vort max over north central IL.
Updated the grids for sprinkles for few hours late this evening.
Clouds have come back into the region with the wave.
&&
.SHORT TERM...(Tonight)
ISSUED AT 256 PM CST SUN DEC 21 2014
Low pressure currently over southern Alberta will track into eastern
South Dakota by 12z Mon. Ahead of the system, a tightening pressure
gradient will produce southeasterly winds of 10 to 15 mph across
central Illinois tonight. Due to these sustained winds and a partly
to mostly cloudy sky, overnight low temperatures will be a few
degrees warmer than last night and several degrees warmer than
either the MAV or MET guidance. Lows will once again be coolest
across the SE KILX CWA where skies will initially be mostly clear
and warmest across the W/NW where clouds will hold firm. Readings
will range from the upper 20s near the Indiana border to the middle
30s along/west of I-55. Any precipitation associated with the
approaching system will remain west of the Mississippi River until
later Monday morning, as forecast soundings remain dry through 12z.
&&
.LONG TERM...(Monday through Sunday)
ISSUED AT 256 PM CST SUN DEC 21 2014
Beginning to look like a good news/bad news scenario setting up with
the storm system expected to impact central and southeast Illinois
from Monday into Christmas Eve. If recent model trends hold, the
good news will be that significant weather related travel impacts
are not expected on Christmas Eve in the area. The bad news, for
some, would be that a "White Christmas" is looking less likely
locally.
We are still looking at active weather the next few days as a
complex, slow moving, storm system impacts the area. A 160+ kt
upper-level jet crashing into the Pacific NW & northern Rockies will
continue to amplify troffing over the middle of the nation, a trof
that will be with us for a few days.
A closed upper low is expected to develop over the northern
Plains/upper Midwest Monday, nearly vertically stacked with an
associated surface low. The WAA/isentropic lift ahead of these lows
will be accompanied by a periods of rainfall from Monday into Monday
night. Then, another vigorous piece of upper energy will round the
base of the mean trof Tuesday into Wednesday, accompanied by the
development of another surface low. This second low will become the
dominant low, with the first low expected to dissipate. A dry slot
is progged to wrap around the initial upper low, no doubt aided by
the secondary wave intercepting much of the deeper moisture. This
dry slot may result in much of Tuesday/Tuesday night ending up dry
across the northwest 1/2 of the forecast area, certainly drier than
it looked yesterday. The southeast 1/2 of the forecast area should
see rain chances persisting Tuesday and Tuesday night, as this area
will be closer to the track of the secondary wave. The remaining
precipitation will change over to light snow on Christmas Eve, but
model agreement is strengthening and this suggests that snowfall
will not be a significant impact across the forecast area.
Mostly dry conditions are expected by Christmas Day as the system
heads northeast into Canada. Another, much weaker, system is progged
to impact the area by Friday. However, guidance suggests that this
system will have minimal moisture to work with until it moves east
of the forecast area. This is because there will not have been much
time for the atmosphere to recover from the cold/dry advection in
the wake of the midweek system. So, only have a slight chance of
rain and/or snow for Friday into Friday night. While temperatures
will be above normal for much of this week, they will trend below
normal behind Friday`s system.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
ISSUED AT 538 PM CST SUN DEC 21 2014
Not a lot of changes in the aviation trends. HRRR model continues
to show VFR cigs overnight and delayed the onset of the IFR cigs
in rain slightly tomorrow with the latest NAM model output. Model
soundings continue to show signficant pcpn development in the
morning. Lowered the vsb also by afternoon.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Goetsch
SHORT TERM...Barnes
LONG TERM...Bak
AVIATION...Goetsch
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
401 PM CST SAT DEC 20 2014
.SHORT TERM...
247 PM CST
THROUGH SUNDAY NIGHT...
THE STREAK OF CLOUDY DAYS CONTINUES...WITH THE STUBBORN PATTERN TO
CONTINUE. AS A RESULT OF THE THICK CLOUD COVER...AND LACK OF
ORGANIZED ADVECTION OF ANY WARMER AIR AT THE SFC...TEMPS HAVE HELD
MAINLY ARND 30 TO 35 ACROSS THE BULK OF THE CWFA. SFC RIDGE
CONTINUES TO DRIFT EAST THIS AFTN...WITH A WEAK SOUTHERLY FLOW
DEVELOPING. THERE WAS A WEAK MID-LVL VORT LIFTING NORTHEAST ACROSS
SOUTHERN WISC/WESTERN LOWER MI...WHICH WAS ABLE TO PRODUCE A FEW
FLURRIES ACROSS THE FAR NORTHERN IL AREAS.
THIS AFTN/EARLY EVE LOOKS TO REMAIN QUIET/DRY...WITH A LIGHT
SOUTH/SOUTHEAST WIND. IR IMAGERY SHOWS THE NEXT WAVE ACROSS THE
CENTRAL PLAINS...WHICH IS PROGGED TO ARRIVE ACROSS NORTHWEST IL
AFTER MIDNIGHT. THERE APPEARS TO BE SOME WEAK ADVECTION OF MOISTURE
IN THE LOW-LEVELS OVERNIGHT. SOUNDINGS SUGGEST A NARROW WARM WEDGE
ALOFT WHICH COULD TRANSITION ANY PRECIP OVERNIGHT TO LIQUID. THE
FORCING/OMEGA IS RATHER WEAK...WHICH MAY LIMIT DROPLET SIZE AND
RESULT IN JUST PATCHY FREEZING DRIZZLE. TEMPS WILL LIKELY NOT MOVE
MUCH OVERNIGHT...SO HAVE HELD ONTO MID/UPR 20S OVERNIGHT.
LOCAL ARW8KM SOLUTION INDICATES THE MOISTURE TO BE RATHER MARGINAL
WITH THE SYSTEM ARRIVING OVERNIGHT/SUN MORNING...BUT PROGRESSIVE AND
LIFTING NORTH OF THE CWFA BY MIDDAY. WEAK THERMAL RIDGE AT 850MB
WOULD SUGGEST TEMPS MAY ACTUALLY WARM SUN AFTN...HOWEVER GIVEN THE
STUBBORN PATTERN WE HAVE BEEN IN WOULD LEAN TOWARDS NUDGING TEMPS
DOWN A DEGREE OR TWO. MOISTURE LAYER WILL REMAIN LOCKED IN ACROSS
THE REGION THRU SUN/SUN NGT. WITH A CONTINUED SOUTHERLY FLOW AT THE
SFC...TEMPS WILL LIKELY ONLY FALL TO ARND 30/LOW 30S.
BEACHLER
&&
.LONG TERM...
247 PM CST
MONDAY THROUGH SATURDAY...
500MB TROUGH BEGINS TO DIG INTO THE CENTRAL CONUS MON MORNING...WITH
WARM AIR STEADILY ADVECTING NORTH ACROSS THE FORECAST AREA. WHILE
THE THICK CLOUD COVER WILL PERSIST...THE PUSH OF WARM/MOIST AIR WILL
BRING TEMPS INTO THE 40S THE FAR SOUTHERN CWFA COULD SEE A FEW
LOCATIONS TOUCH THE UPR 40S MON AFTN. PRECIP WILL STEADILY PUSH EAST
AS THE UPPER LEVEL SYSTEM PROGRESSES TOWARDS THE REGION...BUT WITH
THE WARM AIR IN PLACE PRECIP SHUD FALL AS RAIN.
MON NGT THE 500MB VORT WILL SLIDE INTO THE UPPER MIDWEST...BUT THE
TROUGH WILL DIG SOUTH ACROSS THE SOUTHERN PLAINS. GUIDANCE HAS BEEN
INDICATING A SECONDARY SHORTWAVE EJECTING FROM THE TROUGH AXIS...AND
LIFTING IT NORTHEAST ACROSS THE TENN VALLEY CHRISTMAS EVE. THE
NORTHERN SFC LOW WILL BE WRAPPED UP ACROSS CENTRAL WISC TUE...WITH
THE MOIST CHANNEL FEEDING NORTH ACROSS THE FORECAST AREA THRU TUE
AFTN. THE SOUTHERN LOW WILL BE QUICKLY DEEPENING AS IT LIFTS NORTH
ACROSS THE OHIO VALLEY WED MORNING...ALLOWING WINDS TO BE ON THE
INCREASE AND HELPING TO STEADILY TRANSITION PRECIP OVER FROM RAIN TO
SNOW POST FROPA WED MORNING.
THE LAST SEVERAL CYCLES OF GUIDANCE HAVE DEMONSTRATED DIFFERENCES IN
PLACEMENT/TRACK OF THE SFC LOW WED AFTN/EVE. LATEST SOLUTION IS
PROGGED TO LIFT NORTH ACROSS NORTHERN IN AND THEN SLIGHTLY
RETROGRADE ACROSS THE SOUTHERN TIP OF LAKE MICHIGAN WED EVE. THEN BY
CHRISTMAS DAY THE TROUGH WILL BE PIVOTING EAST AND HELPING TO LIFT
THE SFC LOW NORTHEAST AWAY FROM THE REGION. SOME WRAP AROUND
MOISTURE/SNOW LOOKS FAVORABLE WED NGT/THUR MORNING...BEFORE COMING
TO AN END JUST AFTER DAYBREAK CHRISTMAS MORNING. THIS SYSTEM WILL
CONTINUE TO BE CLOSELY MONITORED.
TEMPS WILL BE RETURNING TO MORE SEASONAL CONDS...WITH HIGHS
CHRISTMAS DAY IN THE LOW/MID 30S. FLOW REMAINS RATHER PROGRESSIVE
WITH ANOTHER WEAK PUSH OF WARMER AIR RETURNING FRI AND TEMPS BACK TO
THE UPR 30S/LOW 40S. THEN FOR FRI ENSEMBLES ARE INDICATING YET
ANOTHER TROUGH BEGINNING TO DIG INTO THE CENTRAL CONUS...WITH A SFC
LOW LIFTING NORTHEAST ACROSS THE WESTERN GREAT LAKES.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* MVFR CIGS RETURNING THIS EVENING OR OVERNIGHT.
* PATCHY FREEZING DRIZZLE EARLY SUNDAY.
BMD/IZZI
//DISCUSSION...UPDATED 18Z...
HIGH PRESSURE REMAINS OVER THE REGION TODAY RESULTING IN LIGHT
FLOW...HOWEVER WINDS WILL TREND MORE SOUTHERLY THOUGH THE TAF PERIOD
AS THE HIGH DRIFTS EAST OF THE AREA. MVFR CIGS HAVE SCATTERED AND
DRIFTED EAST OF THE TERMINALS THIS MORNING...BUT EXPECT A RETURN OF
THE MVFR THIS EVENING OR OVERNIGHT...THOUGH SPECIFIC TIMING REMAINS
UNCERTAIN. OVERNIGHT...WARM AIR ADVECTION INCREASES JUST OFF THE
DECK AND MAY ALLOW FOR SOME LIGHT FREEZING DRIZZLE TO DEVELOP WITH
SURFACE TEMPS JUST BELOW FREEZING. FORCING IS BEST OVER NORTH
CENTRAL ILLINOIS SO WILL MAINTAIN PROB30 MENTION AT RFD ONLY FOR
NOW. WINDS WILL GRADUALLY INCREASE THROUGH THE DAY SUNDAY AS THE
GRADIENT TIGHTENS AHEAD OF LOW PRESSURE APPROACHING FROM THE
NORTHWEST.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* MEDIUM CONFIDENCE IN CIG TRENDS BUT LOW IN TIMING.
* LOW CONFIDENCE IN FREEZING DRIZZLE.
BMD/IZZI
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...DRY...MAINLY VFR.
MONDAY...RAIN AND MVFR LIKELY. BREEZY SOUTH-SOUTHEAST WINDS.
TUESDAY...CHANCE OF RAIN. MVFR POSSIBLE. SOUTH WINDS BECOMING WEST.
WEDNESDAY...CHANCE OF SNOW. MVFR/IFR POSSIBLE. NORTHWEST WINDS
BECOMING GUSTY FROM THE WEST.
THURSDAY...DRY. MAINLY VFR. GUSTY WEST WINDS DIMINISHING.
FRIDAY...CHANCE OF RAIN OR SNOW. MVFR POSSIBLE. LIGHT EAST WINDS
BECOMING WEST.
RATZER
&&
.MARINE...
203 PM CST
LIGHT SOUTHEAST TO EAST WINDS WILL INCREASE TO 10-25 KT TOMORROW
MORNING THEN TO 30 KT IN THE AFTERNOON AS THE GRADIENT TIGHTENS
BETWEEN THE DEPARTING HIGH AND THE NEXT LOW. THE LOW MOVES OVER THE
DAKOTAS SUNDAY NIGHT AND MODELS AGREE A BIT MORE IN THE PATTERN
EARLY NEXT WEEK. HAVE MEDIUM CONFIDENCE IN THE WIND FORECAST WITH
THIS NEXT LOW. THE LOW WEAKENS AS IT MOVES OVER WISCONSIN TUESDAY
AND A SECOND LOW FORMS OVER THE SOUTHERN MISSISSIPPI VALLEY TUESDAY
AFTERNOON. THE SECOND LOW WILL RACE NORTH AND DEEPEN REACHING
MICHIGAN WEDNESDAY. MODELS DIFFER ON HOW QUICKLY THE LOW WILL REACH
MICHIGAN. BOTH MODELS CONTINUE TO FEATURE WESTERLY HIGH END GALES
BEHIND THE LOW WEDNESDAY AFTERNOON INTO THURSDAY. WEST WINDS
DIMINISH THURSDAY AS THE LOW CONTINUES OFF TO THE NORTH. THE NEXT
LOW MOVES OVER THE SOUTHERN PLAINS THURSDAY AFTERNOON. GUIDANCE
DIFFERS ON THIS LOWS PATH BUT IT SHOULD IMPACT THE LAKE LATE NEXT
WEEK.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740...10 PM SUNDAY TO 3 AM TUESDAY.
&&
$$
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Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
300 PM CST Sat Dec 20 2014
.SHORT TERM...(Tonight)
ISSUED AT 259 PM CST SAT DEC 20 2014
Cloudy skies persist across much of central Illinois this afternoon:
however, 20z/2pm visible satellite imagery shows a large tear in the
overcast developing from near Decatur southeastward to Flora.
Although the HRRR has been a bit overdone with the clearing, it
continues to suggest at least thinning clouds across the E/SE KILX
CWA late this afternoon into the evening. In fact, with 925mb winds
remaining light/variable and not really picking up a strong S/SW
component until Sunday, portions of the SE may see partly cloudy
conditions persist through the night. Further north and west, low
clouds will be on the increase from the west. Forecast soundings
and model RH profiles indicate that the lowest clouds/fog will
remain just W/NW of central Illinois tonight. Due to cloud cover
and a light S/SE wind, low temperatures will be a couple of degrees
warmer than last night. Coolest readings in the middle 20s will
occur south of I-70 where skies will likely remain partly cloudy,
while lows stay in the upper 20s/lower 30s elsewhere.
&&
.LONG TERM...(Sunday through Saturday)
ISSUED AT 259 PM CST SAT DEC 20 2014
Still looking like only one major system to impact central and
southeast Illinois through the coming week. Unfortunately, the
potential exists for the biggest travel headaches with this system
to arrive later Tuesday night into Christmas Eve. However, it should
be noted that no model consensus exists with respect to this
system`s snow potential locally. In fact, at this point, more model
solutions keep the snowfall minimal than not. Nevertheless, it would
be prudent to keep an eye on the forecast heading into the Christmas
holiday as the ultimate outcome becomes more clear.
High pressure at the surface and mostly neutral upper flow aloft
will keep its grip on the local weather for one more day on Sunday.
Southerly return flow on the back side of the surface ridge will
push temperatures a few degrees warmer than today. Meanwhile, a
vigorous upper wave, currently crashing ashore along the Pacific
Northwest coast, will begin to dig a significant trof over the
Plains, also inducing surface cyclogenesis.
Strong WAA/isentropic ascent ahead of this slow moving system will
begin to spread rain into the area on Monday. The rain chances will
continue into Monday night and Tuesday. This initial part of the
forecast is fairly well agreed upon by the models.
The initial surface low beneath the mean Plains upper trof will not
move much across the northern Plains into the upper Midwest between
Monday and Tuesday. Attention then turns to another vigorous wave
that will round the base of the mean trof Tuesday into Wednesday.
This wave should induce a second surface low, one that will become
dominant, as it lifts northeast into Canada by the end of the week.
The model agreement with the timing/track/strength of this secondary
low by Tuesday night into Wednesday is not very good. The track of
this low is critical to how quickly our precipitation will change
over to snow Tuesday night into Wednesday, and if we will be
impacted by the heavier snowfall within this system`s deformation
zone. While the threat is certainly there, at this point only the
GFS has been impacting the forecast area very significantly.
Behind the midweek system, another wave will arrive by Friday.
However, the models have been trending weaker with this system
overall, as well as drier. So, have backed away from rain and/or
snow chances as this system arrives.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 1140 AM CST SAT DEC 20 2014
MVFR ceilings will gradually spread across central Illinois this
afternoon/evening. 17z/11am obs show MVFR conditions
along/southwest of a KGBG to KSPI line, with VFR ceilings further
east across the remainder of the area. As light S/SE flow
gradually becomes more S/SW, these lower clouds will return to all
terminals by evening. Based on the latest HRRR output, have
introduced MVFR at KPIA by 21z, then further east to KCMI by 03z.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Barnes
LONG TERM...Bak
AVIATION...Barnes
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1153 AM CST SAT DEC 20 2014
.SHORT TERM...
302 AM CST
TODAY THROUGH SUNDAY...
THE MAIN CONCERNS DURING THE SHORT TERM WILL BE WILL BE CENTERED
AROUND THE POTENTIAL FOR SOME FREEZING DRIZZLE ACROSS PORTIONS OF
NORTHERN ILLINOIS LATE TONIGHT INTO EARLY SUNDAY MORNING.
SURFACE HIGH PRESSURE CONTINUES TO BE IN PLACE ACROSS THE GREAT
LAKES REGION EARLY THIS MORNING. HOWEVER...ATTENTION FOR TODAY IS
FOCUSED ON A MID LEVEL DISTURBANCE...CURRENTLY NOTED IN THE WATER
VAPOR IMAGERY ACROSS SOUTHWESTERN IOWA. THIS DISTURBANCE WILL SHIFT
EASTWARD ACROSS CENTRAL AND NORTHERN ILLINOIS THROUGH EARLY THIS
AFTERNOON. OVERALL...MODEL SOUNDINGS DO NOT APPEAR ALL THAT
FAVORABLE FOR ANY LIGHT SNOW. HOWEVER...THERE HAVE BEEN SOME REPORTS
OF LIGHT FLURRIES ACROSS IOWA EARLY THIS MORNING...SO I HAVE OPTED
TO KEEP THE MENTION OF SOME FLURRIES GOING ACROSS THE AREA THROUGH
EARLY AFTERNOON.
WARM AIR ADVECTION/ISENTROPIC ASCENT WILL INCREASE
ACROSS MUCH OF THE MIDWEST AND GREAT LAKES REGION LATER TONIGHT INTO
SUNDAY MORNING IN RESPONSE TO AN INCREASING SOUTHERLY WIND FIELD
AHEAD OF A DEVELOPING STORM SYSTEM ACROSS THE NORTHERN HIGH PLAINS.
IT APPEARS THAT THIS WARM AIR ADVECTION WILL BE ENOUGH TO RESULT IN
THE DEVELOPMENT OF SOME FREEZING DRIZZLE OR LIGHT SNOW. MODEL
SOUNDINGS...ESPECIALLY FROM THE NAM SUGGEST CLOUD HEIGHTS WILL ONLY
REACH TO AROUND -7 DEGREES CELSIUS...SUGGESTING THE POSSIBILITY OF A
DEARTH OF ICE CRYSTALS IN THE CLOUDS. AS SUCH...THIS INCREASES THE
THREAT FOR FREEZING DRIZZLE VERSES LIGHT SNOW. OVERALL...THIS WILL
BE A VERY LIGHT EVENT...AND APPEARS TO MAINLY BE CONFINED ACROSS
NORTH CENTRAL ILLINOIS...THOUGH PORTIONS OF THE CHICAGO AREA COULD
ALSO EXPERIENCE SOME. THE PRIMARY TIMING FOR THIS ACTIVE LOOKS TO
BE AFTER MIDNIGHT TONIGHT THROUGH AROUND MID MORNING ON SUNDAY.
THEREAFTER...SURFACE TEMPERATURES SHOULD WARM ABOVE FREEZING ENDING
THE THREAT OF FREEZING PRECIP.
KJB
&&
.LONG TERM...
347 AM CST
MONDAY THROUGH FRIDAY...
NOT MUCH HAS CHANGED IN THE EXPECTATION OF A TRANSITIONING WEATHER
PATTERN ACROSS THE CONUS SUPPORTIVE OF SEVERAL PERIODS OF INCLEMENT
WEATHER THROUGH MUCH OF THE UPCOMING HOLIDAY WEEK. THEREFORE...THE
MAIN CONCERNS DURING THE LONG TERM PERIOD WILL FOCUS AROUND THE
CHANCES AND TIMING OF RAINFALL MONDAY INTO TUESDAY...THEN THE
POTENTIAL FOR A SIGNIFICANT WINTER STORM SOMEWHERE ACROSS THE GREAT
LAKES REGION INTO CHRISTMAS EVE.
A VERY IMPRESSIVE NORTHERN PACIFIC JET STREAK IS EXPECTED TO DEVELOP
EASTWARD ONSHORE ACROSS THE PACIFIC NORTHWEST BY EARLY SUNDAY...THEN
BEGIN TO DIG A SIGNIFICANT UPPER LEVEL TROUGH ACROSS THE CENTRAL
CONS BY MID WEEK. MODEL GUIDANCE CONTINUES IN GOOD AGREEMENT IN
TRACKING AN INITIAL AREA OF LOW PRESSURE EASTWARD FROM THE NORTHERN
HIGH PLAINS TO THE UPPER MISSISSIPPI VALLEY BY TUESDAY. THIS WOULD
KEEP ALL OF NORTHERN ILLINOIS/NORTHWESTERN INDIANA IN THE WARM
SECTOR THROUGH EARLY TUESDAY...THUS ASIDE FROM A SMALL POSSIBILITY OF
THE PRECIP BEGINNING AS A MIX OF SLEET AND RAIN AT ONSET EARLY
MONDAY...IT APPEARS THAT WE WILL BE IN FOR A RAIN EVENT ACROSS THE
ENTIRE AREA MONDAY AFTERNOON INTO MONDAY NIGHT.
THINGS BEGIN TO GET REALLY TRICKY LATE TUESDAY AND INTO CHRISTMAS
EVE...AS MODEL GUIDANCE IS INSTANT IN SECONDARY VORT MAX DIGGING
SOUTH AND ACROSS THE LOWER MISSISSIPPI VALLEY BY TUESDAY
NIGHT...LEADING TO A VERY AMPLIFIED AND INCREASING NEGATIVELY TILTED
UPPER TROUGH ACROSS THE CENTRAL CONUS. THIS IS A CLASSIC UPPER LEVEL
PATTERN SUPPORTIVE OF TREMENDOUS ATMOSPHERIC DYNAMICS AND HENCE
RAPID AND DEEP CYCLOGENESIS...SOMEWHERE ACROSS THE GREAT LAKES
REGION. IN FACT...THIS COULD RESULT IN "BOMB CYCLOGENESIS"...WHICH IS
DEFINED AS A DEEPENING RATE OF THE LOWS CENTRAL PRESSURE OF 24 MB IN
AS MANY HOURS. MODEL GUIDANCE CONTINUES TO BE IN SOME DISAGREEMENT IN
WHERE EXACTLY THIS STORM SYSTEM WILL TRACK INTO CHRISTMAS EVE.
HOWEVER...SUPPORT IS IN PLACE TO SUGGEST A GOOD POTENTIAL OF A
STRONG STORM SYSTEM ACROSS THE REGION DURING THIS PERIOD.
UNFORTUNATELY...THE ACTUAL TRACK OF THE STORM WILL BE THE DIFFERENCE
IN IF WE END UP WITH LITTLE OR NO SNOW...OR A SIGNIFICANT WINTER
STORM ACROSS THE AREA. THE LIKELIHOOD OF VERY STRONG WINDS WITH SUCH A
DEEP LOW COULD ALSO RESULT IN SIGNIFICANT BLOWING SNOW...IF IT DOES
OF COURSE SNOW THIS FAR WEST. THEREFORE...THIS STORM BEARS
SIGNIFICANT ATTENTION IN THE COMING DAYS.
FOLLOWING THIS SYSTEM...YET ANOTHER STORM SYSTEM COULD TAKE AIM ON
THE AREA BY FRIDAY. HOWEVER...UNCERTAINTY WITH THIS STORM IS
EXTREMELY HIGH...GIVEN THAT THE ACTUAL EVOLUTION OF THE FIRST STORM
SYSTEM WILL NEED TO BE IRONED OUT. OVERALL THOUGH IT LOOKS LIKE WE
ARE ENTERING INTO AN ACTIVE WEATHER PERIOD THROUGH THE REST OF THE
FORECAST PERIOD.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* MVFR CIGS RETURNING THIS EVENING OR OVERNIGHT.
* PATCHY FREEZING DRIZZLE EARLY SUNDAY.
BMD
//DISCUSSION...UPDATED 18Z...
HIGH PRESSURE REMAINS OVER THE REGION TODAY RESULTING IN LIGHT
FLOW...HOWEVER WINDS WILL TREND MORE SOUTHERLY THOUGH THE TAF PERIOD
AS THE HIGH DRIFTS EAST OF THE AREA. MVFR CIGS HAVE SCATTERED AND
DRIFTED EAST OF THE TERMINALS THIS MORNING...BUT EXPECT A RETURN OF
THE MVFR THIS EVENING OR OVERNIGHT...THOUGH SPECIFIC TIMING REMAINS
UNCERTAIN. OVERNIGHT...WARM AIR ADVECTION INCREASES JUST OFF THE
DECK AND MAY ALLOW FOR SOME LIGHT FREEZING DRIZZLE TO DEVELOP WITH
SURFACE TEMPS JUST BELOW FREEZING. FORCING IS BEST OVER NORTH
CENTRAL ILLINOIS SO WILL MAINTAIN PROB30 MENTION AT RFD ONLY FOR
NOW. WINDS WILL GRADUALLY INCREASE THROUGH THE DAY SUNDAY AS THE
GRADIENT TIGHTENS AHEAD OF LOW PRESSURE APPROACHING FROM THE
NORTHWEST.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM CONFIDENCE IN CIG TRENDS BUT LOW IN TIMING.
* LOW CONFIDENCE IN FREEZING DRIZZLE.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...DRY...MAINLY VFR.
MONDAY...RAIN AND MVFR LIKELY. BREEZY SOUTH-SOUTHEAST WINDS.
TUESDAY...CHANCE OF RAIN. MVFR POSSIBLE. SOUTH WINDS BECOMING WEST.
WEDNESDAY...CHANCE OF SNOW. MVFR/IFR POSSIBLE. NORTHWEST WINDS
BECOMING GUSTY FROM THE WEST.
THURSDAY...DRY. MAINLY VFR. GUSTY WEST WINDS DIMINISHING.
FRIDAY...CHANCE OF RAIN OR SNOW. MVFR POSSIBLE. LIGHT EAST WINDS
BECOMING WEST.
RATZER
&&
.MARINE...
137 AM CST
THE MAIN MARINE FORECAST CONCERNS THIS MORNING FOCUS ON A COUPLE OF
PERIODS OF STRONG WINDS OVER THE NEXT SEVERAL DAYS...SOUTH AND
SOUTHEAST WINDS 25-30 KT DEVELOPING SUNDAY AND CONTINUING THROUGH
MONDAY EVENING...THEN THE POTENTIAL FOR WEST HIGH GALES LATE
WEDNESDAY THROUGH THURSDAY...CHRISTMAS EVE AND CHRISTMAS DAY.
IN THE NEAR TERM...WEATHER IS QUITE TRANQUIL ACROSS LAKE MICHIGAN
THIS MORNING AS DIFFUSE HIGH PRESSURE WAS DRIFTING SLOWLY EAST
ACROSS THE REGION. THE RIDGE AXIS WILL SHIFT EAST OF THE LAKE THIS
AFTERNOON ALLOWING CURRENT VARIABLE WINDS TO BECOME SOUTHERLY. SOUTH
WINDS WILL GRADUALLY INCREASE LATE TONIGHT AND SUNDAY AS AN AREA OF
LOW PRESSURE DEVELOPS SOUTHEAST IN THE LEE OF THE NORTHERN ROCKIES
WITH A CORRESPONDING TIGHTENING OF THE SURFACE PRESSURE GRADIENT
BETWEEN THE LOW AND THE HIGH TO EAST OF THE LAKES. MODEL FORECAST
SOUNDINGS SUPPORT WINDS 20-25 KT SUNDAY AFTERNOON INCREASING TO 30
KT SUNDAY NIGHT/MONDAY...BECOMING A BIT MORE SOUTHEAST LATE MONDAY
AS THE SURFACE LOW MOVES INTO THE UPPER MIDWEST.
THE SURFACE LOW IS EXPECTED TO FILL A BIT ACROSS THE REGION TUESDAY
AS IT OCCLUDES. MODEL FORECASTS CONTINUE TO DEPICT A COMPLEX
EVOLUTION BY MID-WEEK HOWEVER...WITH A SECOND AREA OF LOW PRESSURE
FARTHER SOUTH ALONG THE COLD FRONT DEEPENING AND WRAPPING NORTHWARD
INTO THE GREAT LAKES WEDNESDAY AND THURSDAY. SPREAD REMAINS AMONGST
MODEL FORECASTS OF THE EXACT TRACK AND DEPTH OF THIS LOW...BUT IT
DOES APPEAR THAT A DEEPENING SUB-980 MB LOW WILL TRACK NORTH ACROSS
THE GREAT LAKES REGION CHRISTMAS EVE INTO CHRISTMAS DAY. SUCH A LOW
PASSING EAST OF LAKE MICHIGAN SUPPORTS THE POTENTIAL FOR THE
DEVELOPMENT OF WESTERLY GALES ON THE LAKE...PERHAPS HIGH GALES ABOVE
40 KT...FROM WEDNESDAY AFTERNOON OR EVENING THROUGH THE DAY
THURSDAY.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1140 AM CST Sat Dec 20 2014
.UPDATE...
ISSUED AT 1045 AM CST SAT DEC 20 2014
Short-wave trough evident on latest water vapor imagery across
north-central Illinois will continue to track eastward out of the
area this afternoon. Despite weak synoptic lift associated with
this feature, little or no light precip has been observed. Clouds
blanket central Illinois, with lower clouds/fog remaining further
west across Iowa into northern/central Missouri. 16z LAPS soundings
show a dry layer below 900mb, which is not conducive for drizzle.
As a result, have removed the drizzle/flurry mention across the
far northern KILX CWA this morning. Will generally be a cloudy and
cold day across central Illinois: however, a few breaks in the
overcast will be possible from time to time. As low-level flow
gradually veers more southwesterly, lower clouds/drizzle/fog
currently west of the Mississippi River will spill eastward into
the Illinois River Valley tonight.
&&
.SHORT TERM...(Today)
ISSUED AT 507 AM CST SAT DEC 20 2014
Latest satellite data indicating a shortwave trof near Omaha which
is expected to push across our area later this morning. Upstream
surface observations across central and east central Iowa have had
some reports of some very light freezing drizzle and flurries to the
east of the main area of lift, with even some very light flurries
reported this past hour in St. Louis. A secondary shortwave was
noted over parts of southern Missouri into the lower Ohio Valley
that has produced a band of light snow which extended along and
south of the I-70 corridor early this morning. That system will
shift off to our east over the next few hours taking the light snow
out of southeast Illinois by dawn.
As the compact shortwave over the Missouri Valley tracks across the
area, many of the forecast soundings are not showing much in the way
of support for widespread precip as high pressure at the surface is
still holding firm over east central Illinois this morning. We see
moisture in the 850-800 mb layer over most of the area with not a
great deal above that until later this morning when the main area of
lift associated with the vort max swings thru. Much of the stratus/low
level moisture will remain to our west thru the morning as well before
tracking slowing into west central Illinois this afternoon. Will carry
chances for flurries this morning, mainly over west central Illinois
ahead of the vort max, as we see some mid level moisture/lift track
just to the west of our forecast area. Most of the short term high
resolution models continue to suggest as the shortwave moves across
the remainder of the state, moisture profiles will not support much
in the way of precip further east this afternoon. Despite the more
widespread cloud cover over our area today, we should see afternoon
temperatures a few degrees warmer than yesterday with readings
ranging from the mid 30s north to around 40 south.
&&
.LONG TERM...(Tonight through Friday)
ISSUED AT 507 AM CST SAT DEC 20 2014
Fairly quiet weather expected tonight through Sunday night across
central and southeast IL as surface ridge shifts east into New
England and the mid Atlantic states Sunday. Temps to gradually
modify next few days with increasing southerly flow especially by
Monday. Added patchy drizzle/freezing drizzle to the IL river valley
overnight with the low clouds as surface temps are close to
freezing. Mostly cloudy skies expected Sunday with more low clouds
prevailing over northern counties. Highs in the lower 40s Sunday
which will be a bit above normal highs in the mid to upper 30s.
Added slight chance of light rain late Sunday night around Galesburg
with best rain chances arriving during the day Monday especially by
Monday afternoon NW areas and Monday night into Tue across area.
Strong low pressure near Pacific NW to track into MN Monday night
and increase chances of rain over IL ahead of approaching low
pressure and cold front. Milder highs in the 40s Monday and Tue with
Lawrenceville around 50F.
Forecast models then deepen another area of low pressure from the
southern plains into KY by dawn Wed and then into eastern lower MI
or just east of there by sunset Wed. Colder air to be drawn into IL
Tue night and Wed with rain changing to snow during Tue night and
continue good chances of light snow Wed. Could be some light snow
accumulations overnight Tue night into Wed especially over
eastcentral IL. Windy conditions expected Wed and Wed night as
deepening low pulls away with strong west winds gusting 25-35 mph.
Dry conditions expected on Christmas Day over the state as IL will
be in between strong low pressure exiting into eastern Canada and new
low pressure developing over Texas Panhandle by sunset Thu. This low
pressure ejects ne into the western Great Lakes by sunset Friday and
returns good chances of precipitation with southeast IL mainly rain
and a mix of rain/snow over central IL. Extended models show active
weather pattern looks to continue beyond day 7.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 1140 AM CST SAT DEC 20 2014
MVFR ceilings will gradually spread across central Illinois this
afternoon/evening. 17z/11am obs show MVFR conditions
along/southwest of a KGBG to KSPI line, with VFR ceilings further
east across the remainder of the area. As light S/SE flow
gradually becomes more S/SW, these lower clouds will return to all
terminals by evening. Based on the latest HRRR output, have
introduced MVFR at KPIA by 21z, then further east to KCMI by 03z.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Barnes
SHORT TERM...Smith
LONG TERM...07
AVIATION...Barnes
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
303 AM CST SAT DEC 20 2014
...SHORT TERM...TODAY THROUGH SUNDAY...
302 AM CST
THE MAIN CONCERNS DURING THE SHORT TERM WILL BE WILL BE CENTERED
AROUND THE POTENTIAL FOR SOME FREEZING DRIZZLE ACROSS PORTIONS OF
NORTHERN ILLINOIS LATE TONIGHT INTO EARLY SUNDAY MORNING.
SURFACE HIGH PRESSURE CONTINUES TO BE IN PLACE ACROSS THE GREAT
LAKES REGION EARLY THIS MORNING. HOWEVER...ATTENTION FOR TODAY IS
FOCUSED ON A MID LEVEL DISTURBANCE...CURRENTLY NOTED IN THE WATER
VAPOR IMAGERY ACROSS SOUTHWESTERN IOWA. THIS DISTURBANCE WILL SHIFT
EASTWARD ACROSS CENTRAL AND NORTHERN ILLINOIS THROUGH EARLY THIS
AFTERNOON. OVERALL...MODEL SOUNDINGS DO NOT APPEAR ALL THAT
FAVORABLE FOR ANY LIGHT SNOW. HOWEVER...THERE HAVE BEEN SOME REPORTS
OF LIGHT FLURRIES ACROSS IOWA EARLY THIS MORNING...SO I HAVE OPTED
TO KEEP THE MENTION OF SOME FLURRIES GOING ACROSS THE AREA THROUGH
EARLY AFTERNOON.
WARM AIR ADVECTION/ISENTROPIC ASCENT WILL INCREASE
ACROSS MUCH OF THE MIDWEST AND GREAT LAKES REGION LATER TONIGHT INTO
SUNDAY MORNING IN RESPONSE TO AN INCREASING SOUTHERLY WIND FIELD
AHEAD OF A DEVELOPING STORM SYSTEM ACROSS THE NORTHERN HIGH PLAINS.
IT APPEARS THAT THIS WARM AIR ADVECTION WILL BE ENOUGH TO RESULT IN
THE DEVELOPMENT OF SOME FREEZING DRIZZLE OR LIGHT SNOW. MODEL
SOUNDINGS...ESPECIALLY FROM THE NAM SUGGEST CLOUD HEIGHTS WILL ONLY
REACH TO AROUND -7 DEGREES CELSIUS...SUGGESTING THE POSSIBILITY OF A
DEARTH OF ICE CRYSTALS IN THE CLOUDS. AS SUCH...THIS INCREASES THE
THREAT FOR FREEZING DRIZZLE VERSES LIGHT SNOW. OVERALL...THIS WILL
BE A VERY LIGHT EVENT...AND APPEARS TO MAINLY BE CONFINED ACROSS
NORTH CENTRAL ILLINOIS...THOUGH PORTIONS OF THE CHICAGO AREA COULD
ALSO EXPERIENCE SOME. THE PRIMARY TIMING FOR THIS ACTIVE LOOKS TO
BE AFTER MIDNIGHT TONIGHT THROUGH AROUND MID MORNING ON SUNDAY.
THEREAFTER...SURFACE TEMPERATURES SHOULD WARM ABOVE FREEZING ENDING
THE THREAT OF FREEZING PRECIP.
KJB
&&
LONG TERM...MONDAY THROUGH FRIDAY...
NOT MUCH HAS CHANGED IN THE EXPECTATION OF A TRANSITIONING WEATHER
PATTERN ACROSS THE CONUS SUPPORTIVE OF SEVERAL PERIODS OF INCLEMENT
WEATHER THROUGH MUCH OF THE UPCOMING HOLIDAY WEEK. THEREFORE...THE
MAIN CONCERNS DURING THE LONG TERM PERIOD WILL FOCUS AROUND THE
CHANCES AND TIMING OF RAINFALL MONDAY INTO TUESDAY...THEN THE
POTENTIAL FOR A SIGNIFICANT WINTER STORM SOMEWHERE ACROSS THE GREAT
LAKES REGION INTO CHRISTMAS EVE.
A VERY IMPRESSIVE NORTHERN PACIFIC JET STREAK IS EXPECTED TO DEVELOP
EASTWARD ONSHORE ACROSS THE PACIFIC NORTHWEST BY EARLY SUNDAY...THEN
BEGIN TO DIG A SIGNIFICANT UPPER LEVEL TROUGH ACROSS THE CENTRAL
CONS BY MID WEEK. MODEL GUIDANCE CONTINUES IN GOOD AGREEMENT IN
TRACKING AN INITIAL AREA OF LOW PRESSURE EASTWARD FROM THE NORTHERN
HIGH PLAINS TO THE UPPER MISSISSIPPI VALLEY BY TUESDAY. THIS WOULD
KEEP ALL OF NORTHERN ILLINOIS/NORTHWESTERN INDIANA IN THE WARM
SECTOR THROUGH EARLY TUESDAY...THUS ASIDE FROM A SMALL POSSIBILITY OF
THE PRECIP BEGINNING AS A MIX OF SLEET AND RAIN AT ONSET EARLY
MONDAY...IT APPEARS THAT WE WILL BE IN FOR A RAIN EVENT ACROSS THE
ENTIRE AREA MONDAY AFTERNOON INTO MONDAY NIGHT.
THINGS BEGIN TO GET REALLY TRICKY LATE TUESDAY AND INTO CHRISTMAS
EVE...AS MODEL GUIDANCE IS INSTANT IN SECONDARY VORT MAX DIGGING
SOUTH AND ACROSS THE LOWER MISSISSIPPI VALLEY BY TUESDAY
NIGHT...LEADING TO A VERY AMPLIFIED AND INCREASING NEGATIVELY TILTED
UPPER TROUGH ACROSS THE CENTRAL CONUS. THIS IS A CLASSIC UPPER LEVEL
PATTERN SUPPORTIVE OF TREMENDOUS ATMOSPHERIC DYNAMICS AND HENCE
RAPID AND DEEP CYCLOGENESIS...SOMEWHERE ACROSS THE GREAT LAKES
REGION. IN FACT...THIS COULD RESULT IN "BOMB CYCLOGENESIS"...WHICH IS
DEFINED AS A DEEPENING RATE OF THE LOWS CENTRAL PRESSURE OF 24 MB IN
AS MANY HOURS. MODEL GUIDANCE CONTINUES TO BE IN SOME DISAGREEMENT IN
WHERE EXACTLY THIS STORM SYSTEM WILL TRACK INTO CHRISTMAS EVE.
HOWEVER...SUPPORT IS IN PLACE TO SUGGEST A GOOD POTENTIAL OF A
STRONG STORM SYSTEM ACROSS THE REGION DURING THIS PERIOD.
UNFORTUNATELY...THE ACTUAL TRACK OF THE STORM WILL BE THE DIFFERENCE
IN IF WE END UP WITH LITTLE OR NO SNOW...OR A SIGNIFICANT WINTER
STORM ACROSS THE AREA. THE LIKELIHOOD OF VERY STRONG WINDS WITH SUCH A
DEEP LOW COULD ALSO RESULT IN SIGNIFICANT BLOWING SNOW...IF IT DOES
OF COURSE SNOW THIS FAR WEST. THEREFORE...THIS STORM BEARS
SIGNIFICANT ATTENTION IN THE COMING DAYS.
FOLLOWING THIS SYSTEM...YET ANOTHER STORM SYSTEM COULD TAKE AIM ON
THE AREA BY FRIDAY. HOWEVER...UNCERTAINTY WITH THIS STORM IS
EXTREMELY HIGH...GIVEN THAT THE ACTUAL EVOLUTION OF THE FIRST STORM
SYSTEM WILL NEED TO BE IRONED OUT. OVERALL THOUGH IT LOOKS LIKE WE
ARE ENTERING INTO AN ACTIVE WEATHER PERIOD THROUGH THE REST OF THE
FORECAST PERIOD.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* MVFR CEILINGS LIKELY BECOMING VFR BEFORE SUNRISE. EXPECTED TO
LOWER TO MVFR AGAIN THIS EVENING.
* LIGHT/VARIABLE WINDS BECOMING LIGHT SOUTH-SOUTHWEST BY MIDDAY.
RATZER
//DISCUSSION...UPDATED 06Z...
WEAK SURFACE HIGH PRESSURE RIDGE MOVING SLOWLY EAST ACROSS THE
AREA THIS MORNING. CALM OR LIGHT/VARIABLE WINDS AND MVFR CLOUDS
TRAPPED BENEATH SHALLOW INVERSION PERSISTING. SURFACE OBS INDICATE
MVFR CEILINGS ERODING FROM THE SOUTHWEST HOWEVER...WITH THE
POTENTIAL FOR CONDITIONS TO BECOME VFR AT TAF SITES DURING THE
PRE-DAWN HOURS. QUESTION IS HOW LONG VFR LASTS...AS EXTENSIVE AREA
OF MVFR/IFR CEILINGS WEST OF THE MISSISSIPPI RIVER WILL EVENTUALLY
SPREAD INTO THE AREA TONIGHT. KRFD BEING FARTHER WEST LOOKS TO BE
BACK INTO MVFR CONDITIONS PERHAPS AS EARLY AS MID-LATE MORNING.
CEILINGS WILL LIKELY LOWER INTO IFR RANGE LATE THIS EVENING INTO
EARLY SUNDAY...WITH THE POTENTIAL FOR SOME FLURRIES OR FREEZING
DRIZZLE DEVELOPING SUNDAY MORNING.
CALM OR LIGHT/VARIABLE WINDS LESS THAN 5 KT WILL BECOME SOUTH-
SOUTHWEST AT 5 KT BY EARLY AFTERNOON AND REMAIN LIGHT SOUTH
THROUGH TONIGHT.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* MEDIUM IN CEILING TRENDS AND VFR DURATION TODAY.
* HIGH IN WIND TRENDS.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...MVFR CIGS. SOUTH WINDS.
MONDAY...MVFR CIGS. BRIEF PERIOD OF RAIN OR MIXED RAIN AND SNOW.
TUESDAY...MVFR CIGS. CHANCE OF RAIN.
WEDNESDAY...MVFR CIGS. BLUSTERY - GUSTY WEST WINDS. CHANCE OF
SNOW.
THURSDAY...VFR.
ED F
&&
.MARINE...
137 AM CST
THE MAIN MARINE FORECAST CONCERNS THIS MORNING FOCUS ON A COUPLE OF
PERIODS OF STRONG WINDS OVER THE NEXT SEVERAL DAYS...SOUTH AND
SOUTHEAST WINDS 25-30 KT DEVELOPING SUNDAY AND CONTINUING THROUGH
MONDAY EVENING...THEN THE POTENTIAL FOR WEST HIGH GALES LATE
WEDNESDAY THROUGH THURSDAY...CHRISTMAS EVE AND CHRISTMAS DAY.
IN THE NEAR TERM...WEATHER IS QUITE TRANQUIL ACROSS LAKE MICHIGAN
THIS MORNING AS DIFFUSE HIGH PRESSURE WAS DRIFTING SLOWLY EAST
ACROSS THE REGION. THE RIDGE AXIS WILL SHIFT EAST OF THE LAKE THIS
AFTERNOON ALLOWING CURRENT VARIABLE WINDS TO BECOME SOUTHERLY. SOUTH
WINDS WILL GRADUALLY INCREASE LATE TONIGHT AND SUNDAY AS AN AREA OF
LOW PRESSURE DEVELOPS SOUTHEAST IN THE LEE OF THE NORTHERN ROCKIES
WITH A CORRESPONDING TIGHTENING OF THE SURFACE PRESSURE GRADIENT
BETWEEN THE LOW AND THE HIGH TO EAST OF THE LAKES. MODEL FORECAST
SOUNDINGS SUPPORT WINDS 20-25 KT SUNDAY AFTERNOON INCREASING TO 30
KT SUNDAY NIGHT/MONDAY...BECOMING A BIT MORE SOUTHEAST LATE MONDAY
AS THE SURFACE LOW MOVES INTO THE UPPER MIDWEST.
THE SURFACE LOW IS EXPECTED TO FILL A BIT ACROSS THE REGION TUESDAY
AS IT OCCLUDES. MODEL FORECASTS CONTINUE TO DEPICT A COMPLEX
EVOLUTION BY MID-WEEK HOWEVER...WITH A SECOND AREA OF LOW PRESSURE
FARTHER SOUTH ALONG THE COLD FRONT DEEPENING AND WRAPPING NORTHWARD
INTO THE GREAT LAKES WEDNESDAY AND THURSDAY. SPREAD REMAINS AMONGST
MODEL FORECASTS OF THE EXACT TRACK AND DEPTH OF THIS LOW...BUT IT
DOES APPEAR THAT A DEEPENING SUB-980 MB LOW WILL TRACK NORTH ACROSS
THE GREAT LAKES REGION CHRISTMAS EVE INTO CHRISTMAS DAY. SUCH A LOW
PASSING EAST OF LAKE MICHIGAN SUPPORTS THE POTENTIAL FOR THE
DEVELOPMENT OF WESTERLY GALES ON THE LAKE...PERHAPS HIGH GALES ABOVE
40 KT...FROM WEDNESDAY AFTERNOON OR EVENING THROUGH THE DAY
THURSDAY.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
330 AM CST Sat Dec 20 2014
.SHORT TERM...(Today)
ISSUED AT 329 AM CST SAT DEC 20 2014
Latest satellite data indicating a shortwave trof near Omaha which
is expected to push across our area later this morning. Upstream
surface observations across central and east central Iowa have had
some reports of some very light freezing drizzle and flurries to the
east of the main area of lift, with even some very light flurries
reported this past hour in St. Louis. A secondary shortwave was
noted over parts of southern Missouri into the lower Ohio Valley
that has produced a band of light snow which extended along and
south of the I-70 corridor early this morning. That system will
shift off to our east over the next few hours taking the light snow
out of southeast Illinois by dawn.
As the compact shortwave over the Missouri Valley tracks across the
area, many of the forecast soundings are not showing much in the way
of support for widespread precip as high pressure at the surface is
still holding firm over east central Illinois this morning. We see
moisture in the 850-800 mb layer over most of the area with not a
great deal above that until later this morning when the main area of
lift associated with the vort max swings thru. Much of the stratus/low
level moisture will remain to our west thru the morning as well before
tracking slowing into west central Illinois this afternoon. Will carry
chances for flurries this morning, mainly over west central Illinois
ahead of the vort max, as we see some mid level moisture/lift track
just to the west of our forecast area. Most of the short term high
resolution models continue to suggest as the shortwave moves across
the remainder of the state, moisture profiles will not support much
in the way of precip further east this afternoon. Despite the more
widespread cloud cover over our area today, we should see afternoon
temperatures a few degrees warmer than yesterday with readings
ranging from the mid 30s north to around 40 south.
&&
.LONG TERM...(Tonight through Friday)
ISSUED AT 329 AM CST SAT DEC 20 2014
Fairly quiet weather expected tonight through Sunday night across
central and southeast IL as surface ridge shifts east into New
England and the mid Atlantic states Sunday. Temps to gradually
modify next few days with increasing southerly flow especially by
Monday. Added patchy drizzle/freezing drizzle to the IL river valley
overnight with the low clouds as surface temps are close to
freezing. Mostly cloudy skies expected Sunday with more low clouds
prevailing over northern counties. Highs in the lower 40s Sunday
which will be a bit above normal highs in the mid to upper 30s.
Added slight chance of light rain late Sunday night around Galesburg
with best rain chances arriving during the day Monday especially by
Monday afternoon NW areas and Monday night into Tue across area.
Strong low pressure near Pacific NW to track into MN Monday night
and increase chances of rain over IL ahead of approaching low
pressure and cold front. Milder highs in the 40s Monday and Tue with
Lawrenceville around 50F.
Forecast models then deepen another area of low pressure from the
southern plains into KY by dawn Wed and then into eastern lower MI
or just east of there by sunset Wed. Colder air to be drawn into IL
Tue night and Wed with rain changing to snow during Tue night and
continue good chances of light snow Wed. Could be some light snow
accumulations overnight Tue night into Wed especially over
eastcentral IL. Windy conditions expected Wed and Wed night as
deepening low pulls away with strong west winds gusting 25-35 mph.
Dry conditions expected on Christmas Day over the state as IL will
be inbetween strong low pressure exiting into eastern Canada and new
low pressure developing over Texas Panhandle by sunset Thu. This low
pressure ejects ne into the western Great Lakes by sunset Friday and
returns good chances of precipitation with southeast IL mainly rain
and a mix of rain/snow over central IL. Extended models show active
weather pattern looks to continue beyond day 7.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
ISSUED AT 1118 PM CST FRI DEC 19 2014
VFR conditions will begin the TAF period for most of the TAF
sites...with the exception being CMI where MVFR VIS is already in
place. Some of the issues with the TAFs tonight are the timing of
MVFR VIS and lowering CIGs. The surface high that was over
Illinois earlier is slowly pushing east with light to calm winds
remaining over much of central Illinois. Winds are also slowly
shifting to the east southeast allowing the low level moisture to
filter in both from the east and the west. Locations over Missouri
and Indiana have MVFR VIS and CIGs with locations in Missouri
under IFR CIGs. Given the complexity involved with timing of lower
VIS and CIGs...confidence is fairly low in the TAF forecast past
the first 6 hours. Currently have MVFR conditions over PIA
starting at 09Z...at 08Z for BMI and DEC...and at 12Z for SPI.
Mainly went with the HRRR since it seemed to have a pretty good
handle on the previous forecast. Also included a TEMPO group for
CMI as all guidance had IFR VIS over the site between 09Z and 13Z.
Only included a TEMPO for now since confidence in the timing is
lower. VFR conditions could resume around 16Z for the sites after
the next upper level wave moves through Illinois...but this could
change with the next TAF issuance.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Smith
LONG TERM...07
AVIATION...ALW
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1155 PM CST FRI DEC 19 2014
.SHORT TERM...
237 PM CST
THROUGH SATURDAY...
UNFORTUNATELY IT LOOKS LIKE WE WILL REMAIN LOCKED IN THE CLOUDS YET
AGAIN TONIGHT...DESPITE A CLEARING WEDGE THAT EXTENDS FROM
WESTCENTRAL IL TO SOUTHERN IN. WITH HIGH PRESSURE OVERHEAD THE
ABILITY TO MIX TO THE SFC DRIER AIR HAS BEEN NONEXISTENT. WITH THE
CONSIDERABLE SOLAR SHIELDING THIS AFTERNOON...SFC TEMPS HAVE BEEN
UNABLE TO WARM MUCH. TEMPS IN MOST LOCATIONS HAVE REMAINED ARND 30
TO A FEW LOW 30S ACROSS THE FAR SOUTHERN CWFA. OVERNIGHT THE SFC
RIDGE WILL DRIFT EAST...ALLOWING LGT/VRB WINDS TO SLOWLY TURN
SOUTHWESTERLY BY DAYBREAK SAT. OVERNIGHT LOWS WILL GENERALLY BE IN
THE LOW/MID 20S...BUT IF CLOUDS REMAIN THICK ENOUGH IT IS PLAUSIBLE
THAT TEMPS COULD HOLD IN THE MID/UPR 20S. GUIDANCE HAS INDICATED A
WEAK LOBE OF VORTICITY ALONG THE NORTHERN STREAM PUSHING EAST ACROSS
THE NORTHERN PLAINS OVERNIGHT...ARRIVING ACROSS THE GREAT LAKES
REGION AROUND SAT MORNING. WHILE IT APPEARS MOST OF THE NEAR SFC
WILL REMAIN DRY...THERE IS SOME WEAK FORCING IN THE MID-LVLS ALONG
WITH MARGINAL SATURATION THAT SOME FLURRIES COULD OCCUR DURING THE
MORNING HOURS. WITH YET ANOTHER DAY OF CONTINUED CLOUDINESS SAT...IT
APPEARS LESS FAVORABLE FOR ANY BUMP TO THE TEMPS. SO HAVE NUDGED
TEMPS DOWN A DEGREE TO THE MID 30S ACROSS THE CWFA.
SATURDAY NIGHT WILL GENERALLY REMAIN DRY...HOWEVER THERE IS ANOTHER
WEAK VORT TRYING TO LIFT NORTHEAST ACROSS IOWA LATE SAT NGT/EARLY
SUN. WITH A SLIGHT WARM LAYER TRYING TO LIFT ACROSS THE
REGION...HOWEVER HAVE HELD ONTO MAINLY LGT SNOW. THERE IS SOME
CONCERN THAT TEMPS ALOFT COULD BE WARM ENOUGH TO FULLY MELT ANY
DENDRITES. THE OTHER CONCERN WORTH MENTIONING IS THAT THE LIFT/OMEGA
IS LACKING LATE SAT NGT...SO DROPLET SIZE COULD BE SMALL AND INSTEAD
OF ANY DENDRITES THERE COULD END UP BEING PATCHY FREEZING
DRIZZLE...MAINLY AFTER MIDNIGHT.
BEACHLER
&&
.LONG TERM...
237 PM CST
SUNDAY THROUGH SATURDAY...
500MB TROUGH WILL BEGIN TO DIG SOUTH ACROSS THE CENTRAL CONUS SUN
INTO MON...WITH A SERIES OF MID-LVL VORTS PROGGED TO SLIDE SOUTHEAST
ACROSS THE CANADIAN ROCKIES INTO THE NORTHERN PLAINS. THE MAIN FOCUS
WILL BE ON A STRONGER SHORTWAVE DEVELOPING SUN NGT/EARLY MON ACROSS
THE DAKOTAS...EXPECTED TO SLIDE SOUTHEAST ACROSS NORTHERN IL.
ALTHOUGH CONFIDENCE IN THE TIMING/PLACEMENT OF THIS PATH IS LOW
GIVEN CONTINUED CORRECTIONS BASED ON THE LATEST GUIDANCE CYCLES.
MOISTURE WILL BE ADVECTING NORTH OF THIS LOW MON...WITH PRECIP
ARRIVING MON MORNING LIKELY AS MAINLY RAIN OR PERHAPS A RAIN/SNOW
MIX ACROSS THE NORTHERN CWFA. THEN A QUICK PUSH OF MUCH WARMER AIR
WILL BRING TEMPS INTO THE UPR 30S/NEAR 40 MON AFTN AND SHOULD TURN
ANY PRECIP TO PLAIN RAIN. AS MON NGT PROGRESSES...THE LOW IS PROGGED
TO STEADILY DEEPEN AND LIFT NORTHEAST ACROSS NORTHERN IL EARLY TUE.
FROPA CURRENTLY PROGGED FOR TUE EVE...BRINGING COLDER AIR BACK INTO
THE FORECAST AREA AND TURNING RAIN OVER TO LGT SNOW.
MON NGT WITH THE WARM AIR STEADILY ADVECTING NORTH...TEMPS WILL
REMAIN IN THE MID/UPR 30S. TUE TEMPS COULD PUSH EVEN
WARMER...DEPENDING ON THE PLACEMENT/TIMING OF FROPA. CURRENT
INDICATIONS ARE THAT TEMPS WILL PUSH INTO THE LOW/MID 40S TUE AFTN.
CHRISTMAS EVE THROUGH CHRISTMAS DAY...
ENSEMBLES ALONG WITH OPERATIONAL SOLUTIONS HAVE BEEN TARGETING THE
SYSTEM BECOMING WRAPPED UP OVER THE GREAT LAKES REGION AND POSSIBLY
TRANSITIONING INTO ANOTHER LOW OVER SOUTHERN ONTARIO/SOUTHWEST
QUEBEC CHRISTMAS DAY. A TIGHT GRADIENT WILL REMAIN OVER THE REGION
BOTH CHRISTMAS EVE/CHRISTMAS DAY...WITH TEMPS RETURNING TO MORE
SEASONAL CONDITIONS IN THE LOW/MID 30S.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* MVFR CEILINGS LIKELY BECOMING VFR BEFORE SUNRISE. EXPECTED TO
LOWER TO MVFR AGAIN THIS EVENING.
* LIGHT/VARIABLE WINDS BECOMING LIGHT SOUTH-SOUTHWEST BY MIDDAY.
RATZER
//DISCUSSION...UPDATED 06Z...
WEAK SURFACE HIGH PRESSURE RIDGE MOVING SLOWLY EAST ACROSS THE
AREA THIS MORNING. CALM OR LIGHT/VARIABLE WINDS AND MVFR CLOUDS
TRAPPED BENEATH SHALLOW INVERSION PERSISTING. SURFACE OBS INDICATE
MVFR CEILINGS ERODING FROM THE SOUTHWEST HOWEVER...WITH THE
POTENTIAL FOR CONDITIONS TO BECOME VFR AT TAF SITES DURING THE
PRE-DAWN HOURS. QUESTION IS HOW LONG VFR LASTS...AS EXTENSIVE AREA
OF MVFR/IFR CEILINGS WEST OF THE MISSISSIPPI RIVER WILL EVENTUALLY
SPREAD INTO THE AREA TONIGHT. KRFD BEING FARTHER WEST LOOKS TO BE
BACK INTO MVFR CONDITIONS PERHAPS AS EARLY AS MID-LATE MORNING.
CEILINGS WILL LIKELY LOWER INTO IFR RANGE LATE THIS EVENING INTO
EARLY SUNDAY...WITH THE POTENTIAL FOR SOME FLURRIES OR FREEZING
DRIZZLE DEVELOPING SUNDAY MORNING.
CALM OR LIGHT/VARIABLE WINDS LESS THAN 5 KT WILL BECOME SOUTH-
SOUTHWEST AT 5 KT BY EARLY AFTERNOON AND REMAIN LIGHT SOUTH
THROUGH TONIGHT.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM IN CEILING TRENDS AND VFR DURATION TODAY.
* HIGH IN WIND TRENDS.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...MVFR CIGS. SOUTH WINDS.
MONDAY...MVFR CIGS. BRIEF PERIOD OF RAIN OR MIXED RAIN AND SNOW.
TUESDAY...MVFR CIGS. CHANCE OF RAIN.
WEDNESDAY...MVFR CIGS. BLUSTERY - GUSTY WEST WINDS. CHANCE OF
SNOW.
THURSDAY...VFR.
ED F
&&
.MARINE...
200 PM CST
HIGH PRESSURE IS OVER THE REGION AND IT WILL SLOWLY SHIFT EAST
THROUGH SUNDAY NIGHT. LIGHT WINDS BECOME SOUTHWEST OVERNIGHT. THE
NEXT LOW MOVES OVER THE DAKOTAS SUNDAY NIGHT WITH SOUTH WINDS
INCREASING TO 30 KT. MODELS DISAGREE WITH EXACT PATH OF THIS LOW.
ONE HAS THE LOW DEEPENING OVER LAKE SUPERIOR WEDNESDAY WHILE ANOTHER
HAS THE LOW DEEPENING OVER LAKE ERIE. SOUTHEAST WINDS AROUND 25 KT
ARE EXPECTED THROUGH MONDAY NIGHT AHEAD OF THE LOW...THEN WINDS
BECOME WEST BEHIND IT. FOR SPEEDS WENT MIDDLE OF THE ROAD GIVEN THE
VARIABILITY. COULD DEFINITELY SEE HIGHER GUSTS IF THE LOW DEEPENS
CLOSER TO THE LAKE.
MODELS AGREE ON VERY STRONG WINDS BEHIND THE LOW WEDNESDAY NIGHT
THROUGH THURSDAY. HAVE HIGH END GALES IN THE FORECAST AND SOME
GUIDANCE MEMBERS SUGGEST LOW END STORM FORCE GUSTS MAY BE POSSIBLE.
DO NOT HAVE THE CONFIDENCE TO GO THAT HIGH JUST YET...BUT HAVE HIGH
CONFIDENCE IN AT LEAST GALES. THE LOW SHIFTS NORTHEAST WITH WINDS
DIMINISHING THURSDAY NIGHT. THE NEXT LOW HOWEVER MOVES OVER THE
SOUTHERN PLAINS THURSDAY EVENING.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1135 PM CST Fri Dec 19 2014
.UPDATE...
ISSUED AT 905 PM CST FRI DEC 19 2014
The surface ridge axis is finally making some progress to the east
of Illinois, allowing winds west of I-55 to start a trend out of
the southeast. A weak shortwave passing across southern IL could
trigger some light snow showers or flurries southeast of I-70.
Radar returns toward Lawrenceville are mostly virga, with no snow
reaching the ground yet. Cloud heights are lowering with time
under that wave, so some flurries were added to the forecast for
the far southeast counties toward midnight.
The next area of concern is NW of the IL river, where low clouds
and fog may develop into some freezing drizzle toward sunrise. The
precip could fall as flurries, but a lack of ice crystals to feed
into the low cloud layer will limit the ability for snowflakes to
develop. Thus, the concern for FZDZ to occur. Any icing would
cause slippery travel conditions. Have added a mention of FZDZ
between 12z-15z Sat morn, but may need a mention even earlier
depending on speed of saturation and progression of shortwave from
Nebraska across Iowa/N MO.
Low temps will not drop off appreciably from current temps due to
increasing clouds. Updates this evening were to the weather and
sky grids to match expected trends.
&&
.SHORT TERM...(Tonight)
ISSUED AT 328 PM CST FRI DEC 19 2014
20z/2pm visible satellite imagery continues to show a large break in
the overcast extending from southeast Iowa across much of central
Illinois into Kentucky. With high pressure directly overhead and
only very light low-level winds, partly to mostly clear conditions
will persist through the evening hours. As the high begins to shift
eastward, a southerly return flow will gradually develop late
tonight into Saturday, allowing the low clouds currently across
Iowa/Missouri to spill back into the area. End result will be a
mostly clear start to the night, with overcast conditions expected
across the board by dawn Saturday. May also see some patchy fog
west of the I-55 corridor late tonight as low-level moisture
increases, but am not expecting any major restrictions to
visibility. Due to the initially mostly clear skies and light
winds, another cold night is expected with low temperatures
bottoming out in the lower to middle 20s.
&&
.LONG TERM...(Saturday through Friday)
ISSUED AT 328 PM CST FRI DEC 19 2014
A rather quiet weekend is on tap across central and southeast
Illinois, but weather activity will be on the upswing heading into
the Holiday work week.
Model agreement is good through the weekend with mostly neutral
upper-level flow and high pressure expected to be the dominant
player at the surface. A week wave, currently pushing east across
the central Plains, will cross the area early Saturday. However, the
forcing appears too weak, and moisture depth too shallow, to warrant
a mention of any precipitation.
A strong, slow moving system will impact the area from Monday into
Christmas Eve. We will remain on the warm side of the system through
Tuesday, with all precipitation initially expected to fall in the
form of rain. Temperatures ahead of the system will also average
nearly 10 degrees above normal for late December.
The colder air on the back side of the deepening storm system will
arrive for Tuesday night into Christmas Eve. This would support any
remaining precipitation changing over to snow. At this point, the
threat for significant snowfall on the back side of the system seems
low, but some light snow accumulation is likely. The model
agreement/run-to-run consistency is still a little shaky heading
into midweek, so future model trends will need to be monitored very
closely.
Another system is progged to arrive by late in the week, generally
Friday into Saturday. However, model consistency with this system is
poorer than the first, so confidence in the ultimate outcome is not
very high.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
ISSUED AT 1118 PM CST FRI DEC 19 2014
VFR conditions will begin the TAF period for most of the TAF
sites...with the exception being CMI where MVFR VIS is already in
place. Some of the issues with the TAFs tonight are the timing of
MVFR VIS and lowering CIGs. The surface high that was over
Illinois earlier is slowly pushing east with light to calm winds
remaining over much of central Illinois. Winds are also slowly
shifting to the east southeast allowing the low level moisture to
filter in both from the east and the west. Locations over Missouri
and Indiana have MVFR VIS and CIGs with locations in Missouri
under IFR CIGs. Given the complexity involved with timing of lower
VIS and CIGs...confidence is fairly low in the TAF forecast past
the first 6 hours. Currently have MVFR conditions over PIA
starting at 09Z...at 08Z for BMI and DEC...and at 12Z for SPI.
Mainly went with the HRRR since it seemed to have a pretty good
handle on the previous forecast. Also included a TEMPO group for
CMI as all guidance had IFR VIS over the site between 09Z and 13Z.
Only included a TEMPO for now since confidence in the timing is
lower. VFR conditions could resume around 16Z for the sites after
the next upper level wave moves through Illinois...but this could
change with the next TAF issuance.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Shimon
SHORT TERM...Barnes
LONG TERM...Bak
AVIATION...ALW
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1111 AM CST SAT DEC 20 2014
...UPDATE TO AVIATION...
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 342 AM CST SAT DEC 20 2014
WEAK SHORTWAVE TROUGHS ARE PERIODICALLY PROGRESSING ACROSS THE
PLAINS FROM THE WEST. ONE SUCH MINOR WAVE WILL MOVE ACROSS THE
SOUTHERN PLAINS BY TONIGHT. HOWEVER, LEE TROUGHING IN RESPONSE TO
WESTERLY FLOW AT MID LEVELS SEEMS TO BE THE DOMINANT FEATURE THAT
IS AFFECTING THE LOW LEVEL WIND FIELD. EARLY MORNING SATELLITE AND
SURFACE OBSERVATIONS INDICATE LOW STRATUS ACROSS THE SOUTHERN
PLAINS AS FAR NORTH AS PERRYTON AND MEDICINE LODGE. AS SURFACE
TROUGHING ENCOURAGES SOUTHERLY WINDS TODAY, THIS LOW LEVEL
MOISTURE SHOULD PROGRESS NORTHWARD INTO LOCATIONS FROM DODGE CITY
SOUTH AND EAST TO THE OKLAHOMA BORDER. THE NAM HAS A CHARACTERISTIC
BIAS OF BEING TOO DRY AND WARM AT LOWER LEVELS IN CASES SUCH AS
THIS. THE HRRR AND RAP ARE COOLER AND INDICATE LOW CLOUD COVER
PROGRESSING AS FAR NORTH AS DODGE CITY BY EARLY AFTERNOON. CLOUD
COVER WILL TEND TO KEEP DIURNAL RANGES LOWER AND TEMPERATURES
COOLER IN THE AFTERNOON. AS AN EXAMPLE, THE TEMPERATURE AT GAGE,
OKLAHOMA STAYED 41F FROM FRIDAY AFTERNOON THROUGH EARLY THIS
MORNING AS A RESULT OF THE STRATUS. TEMPERATURES SHOULD BE WARMER
TODAY IN LOCATIONS SUCH AS SCOTT CITY AND WAKEENEY WHERE PLENTY OF
SUNSHINE IS EXPECTED. LOW STRATUS WILL PERSIST OR INCREASE IN
AREAL COVERAGE TONIGHT, AND FOG IS POSSIBLE ON THE WESTERN
PERIPHERY OF THE CLOUD SHIELD, SOME OF WHICH COULD BE LOCALLY
DENSE. THE CLOUD COVER AND HIGHER DEWPOINTS OUGHT TO KEEP
TEMPERATURES FROM FALLING A LOT TONIGHT, EXCEPT FOR WEST CENTRAL
KANSAS WHERE LESS CLOUD COVER IS EXPECTED.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 412 AM CST SAT DEC 20 2014
AT THE BEGINNING OF THE EXTENDED PERIOD ON SUNDAY, A SHORTWAVE
TROUGH WILL BE MOVING OUT OF THE WESTERN HIGH PLAINS ACROSS KANSAS.
A SURFACE TROUGH OVER EASTERN COLORADO COULD MOVE OUT INTO FAR
WESTERN KANSAS DURING THE DAY. LOW LEVEL WINDS WILL TAKE ON A MORE
SOUTHWESTERLY DOWNSLOPE FLOW COMPONENT DURING THE DAY IN THAT AREA
AND HELP BOOST TEMPERATURES INTO THE MID/UPPER 50S. FARTHER EAST
ACROSS SOUTHWEST INTO SOUTH CENTRAL KANSAS LOW STRATUS WILL LIKELY
BE IN PLACE DUE TO CONTINUED MOIST SOUTHERLY FLOW. WHILE THE STRATUS
WILL LIKELY ERODE SOMEWHAT DURING THE DAY, AREAS AROUND SOUTH
CENTRAL KANSAS WILL LIKELY STAY SOCKED IN WITH LOW CLOUDS.
BY MONDAY MORNING, A STRENGTHENING UPPER LEVEL SHORTWAVE TROUGH WILL
MOVE FROM SOUTHWEST CANADA AND DEVELOP INTO A CLOSED LOW OVER
SOUTHEAST SOUTH DAKOTA. AS THIS LOW CONTINUES INTO THE MIDWEST
STATES DURING THE DAY, A SHORTWAVE TROUGH WILL DIG SOUTH ACROSS THE
EASTERN ROCKIES AND ADJACENT HIGH PLAINS AND PUSH A COLD FRONT SOUTH
ACROSS WESTERN KANSAS. THE MODELS CONTINUE TO SHOW PRECIPITATION
DEVELOPING ALONG THE FRONT ALONG WITH SOME LINGERING UPSLOPE
PRECIPITATION OVER EASTERN COLORADO AND FAR WESTERN KANSAS DURING
THE DAY. TEMPERATURE PROFILES CONTINUE TO SUGGEST THAT PRECIPITATION
SHOULD MAINLY BE LIQUID. BY MONDAY NIGHT THE MAIN UPPER LEVEL ENERGY
WITH THE WAVE DROPS INTO NEW MEXICO AND WEST TEXAS. FARTHER NORTH
THE TROUGH SWINGS OUT ACROSS THE HIGH PLAINS. THIS COULD BRING A
FEW FLURRIES TO WEST CENTRAL KANSAS LATE MONDAY NIGHT. WILL CARRY
SOME SLIGHT CHANCE POPS FOR THIS.
THE MODELS CONTINUE TO SHOW UNIDIRECTIONAL NORTHERLY FLOW DEVELOPING
THROUGH THE LOWER TO MIDDLE LEVELS OVER THE HIGH PLAINS LATE MONDAY
NIGHT AND CONTINUING INTO TUESDAY. BLUSTERY CONDITIONS WILL DEVELOP
BY EARLY MORNING TUESDAY AND CONTINUE THROUGH THE DAY. SOME 40 TO 45
MPH GUSTS WILL BE POSSIBLE DURING THE DAY.
UPPER LEVEL RIDGING WILL DEVELOP OVER THE CENTRAL HIGH PLAINS
THROUGH THE MIDDLE PART OF THE WEEK AS THE EARLY WEEK SYSTEM MOVES
INTO THE EASTERN CONUS AND ANOTHER WAVE DROPS INTO THE NORTHERN
ROCKIES. THIS NEXT WAVE COULD BRING RAIN OR SNOW TO WESTERN KANSAS
BY AS EARLY AS CHRISTMAS DAY. THE GLOBAL MODELS CONTINUE TO SHOW
SIGNIFICANT RUN TO RUN VARIABILITY WITH THIS WAVE, HOWEVER. AFTER
COLLABORATING WITH SOME OF THE SURROUNDING OFFICES, HAVE INTRODUCED
SOME SMALL POPS FOR RAIN OR SNOW TO CENTRAL KANSAS NEXT THURSDAY
NIGHT AND FRIDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1111 AM CST SAT DEC 20 2014
FORECAST CONCERN IS THE PROBABILITY OF DENSE FOG. HAVE INSERTED 1/4SM
AND FG FOR KGCK/KDDC. CONFIDENCE IS LOWER FOR KHYS. THE LIFR CONDITIONS
SHOULD BEGIN TO IMPROVE BY 15Z TOMORROW. WINDS WILL BE SOUTHERLY
TO SOUTHWESTERLY 5-10 KT.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 46 33 45 34 / 0 0 10 10
GCK 50 27 50 32 / 0 0 10 10
EHA 51 27 57 34 / 0 0 0 20
LBL 48 31 51 33 / 0 0 0 10
HYS 49 31 48 34 / 0 0 10 10
P28 47 37 47 36 / 0 10 10 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...FINCH
LONG TERM...GERARD
AVIATION...SUGDEN
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
539 AM CST SAT DEC 20 2014
...UPDATED AVIATION DISCUSSION...
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 342 AM CST SAT DEC 20 2014
WEAK SHORTWAVE TROUGHS ARE PERIODICALLY PROGRESSING ACROSS THE
PLAINS FROM THE WEST. ONE SUCH MINOR WAVE WILL MOVE ACROSS THE
SOUTHERN PLAINS BY TONIGHT. HOWEVER, LEE TROUGHING IN RESPONSE TO
WESTERLY FLOW AT MID LEVELS SEEMS TO BE THE DOMINANT FEATURE THAT
IS AFFECTING THE LOW LEVEL WIND FIELD. EARLY MORNING SATELLITE AND
SURFACE OBSERVATIONS INDICATE LOW STRATUS ACROSS THE SOUTHERN
PLAINS AS FAR NORTH AS PERRYTON AND MEDICINE LODGE. AS SURFACE
TROUGHING ENCOURAGES SOUTHERLY WINDS TODAY, THIS LOW LEVEL
MOISTURE SHOULD PROGRESS NORTHWARD INTO LOCATIONS FROM DODGE CITY
SOUTH AND EAST TO THE OKLAHOMA BORDER. THE NAM HAS A CHARACTERISTIC
BIAS OF BEING TOO DRY AND WARM AT LOWER LEVELS IN CASES SUCH AS
THIS. THE HRRR AND RAP ARE COOLER AND INDICATE LOW CLOUD COVER
PROGRESSING AS FAR NORTH AS DODGE CITY BY EARLY AFTERNOON. CLOUD
COVER WILL TEND TO KEEP DIURNAL RANGES LOWER AND TEMPERATURES
COOLER IN THE AFTERNOON. AS AN EXAMPLE, THE TEMPERATURE AT GAGE,
OKLAHOMA STAYED 41F FROM FRIDAY AFTERNOON THROUGH EARLY THIS
MORNING AS A RESULT OF THE STRATUS. TEMPERATURES SHOULD BE WARMER
TODAY IN LOCATIONS SUCH AS SCOTT CITY AND WAKEENEY WHERE PLENTY OF
SUNSHINE IS EXPECTED. LOW STRATUS WILL PERSIST OR INCREASE IN
AREAL COVERAGE TONIGHT, AND FOG IS POSSIBLE ON THE WESTERN
PERIPHERY OF THE CLOUD SHIELD, SOME OF WHICH COULD BE LOCALLY
DENSE. THE CLOUD COVER AND HIGHER DEWPOINTS OUGHT TO KEEP
TEMPERATURES FROM FALLING A LOT TONIGHT, EXCEPT FOR WEST CENTRAL
KANSAS WHERE LESS CLOUD COVER IS EXPECTED.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 412 AM CST SAT DEC 20 2014
AT THE BEGINNING OF THE EXTENDED PERIOD ON SUNDAY, A SHORTWAVE
TROUGH WILL BE MOVING OUT OF THE WESTERN HIGH PLAINS ACROSS KANSAS.
A SURFACE TROUGH OVER EASTERN COLORADO COULD MOVE OUT INTO FAR
WESTERN KANSAS DURING THE DAY. LOW LEVEL WINDS WILL TAKE ON A MORE
SOUTHWESTERLY DOWNSLOPE FLOW COMPONENT DURING THE DAY IN THAT AREA
AND HELP BOOST TEMPERATURES INTO THE MID/UPPER 50S. FARTHER EAST
ACROSS SOUTHWEST INTO SOUTH CENTRAL KANSAS LOW STRATUS WILL LIKELY
BE IN PLACE DUE TO CONTINUED MOIST SOUTHERLY FLOW. WHILE THE STRATUS
WILL LIKELY ERODE SOMEWHAT DURING THE DAY, AREAS AROUND SOUTH
CENTRAL KANSAS WILL LIKELY STAY SOCKED IN WITH LOW CLOUDS.
BY MONDAY MORNING, A STRENGTHENING UPPER LEVEL SHORTWAVE TROUGH WILL
MOVE FROM SOUTHWEST CANADA AND DEVELOP INTO A CLOSED LOW OVER
SOUTHEAST SOUTH DAKOTA. AS THIS LOW CONTINUES INTO THE MIDWEST
STATES DURING THE DAY, A SHORTWAVE TROUGH WILL DIG SOUTH ACROSS THE
EASTERN ROCKIES AND ADJACENT HIGH PLAINS AND PUSH A COLD FRONT SOUTH
ACROSS WESTERN KANSAS. THE MODELS CONTINUE TO SHOW PRECIPITATION
DEVELOPING ALONG THE FRONT ALONG WITH SOME LINGERING UPSLOPE
PRECIPITATION OVER EASTERN COLORADO AND FAR WESTERN KANSAS DURING
THE DAY. TEMPERATURE PROFILES CONTINUE TO SUGGEST THAT PRECIPITATION
SHOULD MAINLY BE LIQUID. BY MONDAY NIGHT THE MAIN UPPER LEVEL ENERGY
WITH THE WAVE DROPS INTO NEW MEXICO AND WEST TEXAS. FARTHER NORTH
THE TROUGH SWINGS OUT ACROSS THE HIGH PLAINS. THIS COULD BRING A
FEW FLURRIES TO WEST CENTRAL KANSAS LATE MONDAY NIGHT. WILL CARRY
SOME SLIGHT CHANCE POPS FOR THIS.
THE MODELS CONTINUE TO SHOW UNIDIRECTIONAL NORTHERLY FLOW DEVELOPING
THROUGH THE LOWER TO MIDDLE LEVELS OVER THE HIGH PLAINS LATE MONDAY
NIGHT AND CONTINUING INTO TUESDAY. BLUSTERY CONDITIONS WILL DEVELOP
BY EARLY MORNING TUESDAY AND CONTINUE THROUGH THE DAY. SOME 40 TO 45
MPH GUSTS WILL BE POSSIBLE DURING THE DAY.
UPPER LEVEL RIDGING WILL DEVELOP OVER THE CENTRAL HIGH PLAINS
THROUGH THE MIDDLE PART OF THE WEEK AS THE EARLY WEEK SYSTEM MOVES
INTO THE EASTERN CONUS AND ANOTHER WAVE DROPS INTO THE NORTHERN
ROCKIES. THIS NEXT WAVE COULD BRING RAIN OR SNOW TO WESTERN KANSAS
BY AS EARLY AS CHRISTMAS DAY. THE GLOBAL MODELS CONTINUE TO SHOW
SIGNIFICANT RUN TO RUN VARIABILITY WITH THIS WAVE, HOWEVER. AFTER
COLLABORATING WITH SOME OF THE SURROUNDING OFFICES, HAVE INTRODUCED
SOME SMALL POPS FOR RAIN OR SNOW TO CENTRAL KANSAS NEXT THURSDAY
NIGHT AND FRIDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 539 AM CST SAT DEC 20 2014
MVFR VSBYS WILL IMPROVE TO VFR AT GCK, DDC, AD HYS BY 15Z AS
TEMPERATURES BEGIN TO WARM. MVFR CIGS OVER THE OKLAHOMA AND TEXAS
PANHANDLES COULD MOVE UP INTO SOUTH CENTRAL AND PARTS OF SOUTHWEST
KANSAS TODAY. IT IS NOT CERTAIN THAT THESE LOW CIGS WILL MOVE OVER
DODGE CITY SO WILL MAINTAIN A LOW LEVEL SCATTERED CLOUD DECK AT
THIS TIME. THERE IS SOME POTENTIAL FOR MVFR TO IFR CONDITIONS IN
LOW CLOUDS AND MIST TO REDEVELOP TOWARD THE END OF THE TAF PERIOD.
WILL LEAVE OUT OF THIS TAF UPDATE FOR NOW BUT LATER UPDATES MAY
INCLUDE IT IF IT APPEARS MORE LIKELY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 44 33 52 34 / 0 0 0 10
GCK 50 27 55 32 / 0 0 0 10
EHA 51 27 57 34 / 0 0 0 20
LBL 47 31 56 33 / 0 0 0 10
HYS 49 31 50 34 / 0 0 0 10
P28 46 37 49 36 / 0 0 10 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...FINCH
LONG TERM...GERARD
AVIATION...GERARD
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
413 AM CST SAT DEC 20 2014
...UPDATED LONG TERM DISCUSSION...
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 342 AM CST SAT DEC 20 2014
WEAK SHORTWAVE TROUGHS ARE PERIODICALLY PROGRESSING ACROSS THE
PLAINS FROM THE WEST. ONE SUCH MINOR WAVE WILL MOVE ACROSS THE
SOUTHERN PLAINS BY TONIGHT. HOWEVER, LEE TROUGHING IN RESPONSE TO
WESTERLY FLOW AT MID LEVELS SEEMS TO BE THE DOMINANT FEATURE THAT
IS AFFECTING THE LOW LEVEL WIND FIELD. EARLY MORNING SATELLITE AND
SURFACE OBSERVATIONS INDICATE LOW STRATUS ACROSS THE SOUTHERN
PLAINS AS FAR NORTH AS PERRYTON AND MEDICINE LODGE. AS SURFACE
TROUGHING ENCOURAGES SOUTHERLY WINDS TODAY, THIS LOW LEVEL
MOISTURE SHOULD PROGRESS NORTHWARD INTO LOCATIONS FROM DODGE CITY
SOUTH AND EAST TO THE OKLAHOMA BORDER. THE NAM HAS A CHARACTERISTIC
BIAS OF BEING TOO DRY AND WARM AT LOWER LEVELS IN CASES SUCH AS
THIS. THE HRRR AND RAP ARE COOLER AND INDICATE LOW CLOUD COVER
PROGRESSING AS FAR NORTH AS DODGE CITY BY EARLY AFTERNOON. CLOUD
COVER WILL TEND TO KEEP DIURNAL RANGES LOWER AND TEMPERATURES
COOLER IN THE AFTERNOON. AS AN EXAMPLE, THE TEMPERATURE AT GAGE,
OKLAHOMA STAYED 41F FROM FRIDAY AFTERNOON THROUGH EARLY THIS
MORNING AS A RESULT OF THE STRATUS. TEMPERATURES SHOULD BE WARMER
TODAY IN LOCATIONS SUCH AS SCOTT CITY AND WAKEENEY WHERE PLENTY OF
SUNSHINE IS EXPECTED. LOW STRATUS WILL PERSIST OR INCREASE IN
AREAL COVERAGE TONIGHT, AND FOG IS POSSIBLE ON THE WESTERN
PERIPHERY OF THE CLOUD SHIELD, SOME OF WHICH COULD BE LOCALLY
DENSE. THE CLOUD COVER AND HIGHER DEWPOINTS OUGHT TO KEEP
TEMPERATURES FROM FALLING A LOT TONIGHT, EXCEPT FOR WEST CENTRAL
KANSAS WHERE LESS CLOUD COVER IS EXPECTED.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 412 AM CST SAT DEC 20 2014
AT THE BEGINNING OF THE EXTENDED PERIOD ON SUNDAY, A SHORTWAVE
TROUGH WILL BE MOVING OUT OF THE WESTERN HIGH PLAINS ACROSS KANSAS.
A SURFACE TROUGH OVER EASTERN COLORADO COULD MOVE OUT INTO FAR
WESTERN KANSAS DURING THE DAY. LOW LEVEL WINDS WILL TAKE ON A MORE
SOUTHWESTERLY DOWNSLOPE FLOW COMPONENT DURING THE DAY IN THAT AREA
AND HELP BOOST TEMPERATURES INTO THE MID/UPPER 50S. FARTHER EAST
ACROSS SOUTHWEST INTO SOUTH CENTRAL KANSAS LOW STRATUS WILL LIKELY
BE IN PLACE DUE TO CONTINUED MOIST SOUTHERLY FLOW. WHILE THE STRATUS
WILL LIKELY ERODE SOMEWHAT DURING THE DAY, AREAS AROUND SOUTH
CENTRAL KANSAS WILL LIKELY STAY SOCKED IN WITH LOW CLOUDS.
BY MONDAY MORNING, A STRENGTHENING UPPER LEVEL SHORTWAVE TROUGH WILL
MOVE FROM SOUTHWEST CANADA AND DEVELOP INTO A CLOSED LOW OVER
SOUTHEAST SOUTH DAKOTA. AS THIS LOW CONTINUES INTO THE MIDWEST
STATES DURING THE DAY, A SHORTWAVE TROUGH WILL DIG SOUTH ACROSS THE
EASTERN ROCKIES AND ADJACENT HIGH PLAINS AND PUSH A COLD FRONT SOUTH
ACROSS WESTERN KANSAS. THE MODELS CONTINUE TO SHOW PRECIPITATION
DEVELOPING ALONG THE FRONT ALONG WITH SOME LINGERING UPSLOPE
PRECIPITATION OVER EASTERN COLORADO AND FAR WESTERN KANSAS DURING
THE DAY. TEMPERATURE PROFILES CONTINUE TO SUGGEST THAT PRECIPITATION
SHOULD MAINLY BE LIQUID. BY MONDAY NIGHT THE MAIN UPPER LEVEL ENERGY
WITH THE WAVE DROPS INTO NEW MEXICO AND WEST TEXAS. FARTHER NORTH
THE TROUGH SWINGS OUT ACROSS THE HIGH PLAINS. THIS COULD BRING A
FEW FLURRIES TO WEST CENTRAL KANSAS LATE MONDAY NIGHT. WILL CARRY
SOME SLIGHT CHANCE POPS FOR THIS.
THE MODELS CONTINUE TO SHOW UNIDIRECTIONAL NORTHERLY FLOW DEVELOPING
THROUGH THE LOWER TO MIDDLE LEVELS OVER THE HIGH PLAINS LATE MONDAY
NIGHT AND CONTINUING INTO TUESDAY. BLUSTERY CONDITIONS WILL DEVELOP
BY EARLY MORNING TUESDAY AND CONTINUE THROUGH THE DAY. SOME 40 TO 45
MPH GUSTS WILL BE POSSIBLE DURING THE DAY.
UPPER LEVEL RIDGING WILL DEVELOP OVER THE CENTRAL HIGH PLAINS
THROUGH THE MIDDLE PART OF THE WEEK AS THE EARLY WEEK SYSTEM MOVES
INTO THE EASTERN CONUS AND ANOTHER WAVE DROPS INTO THE NORTHERN
ROCKIES. THIS NEXT WAVE COULD BRING RAIN OR SNOW TO WESTERN KANSAS
BY AS EARLY AS CHRISTMAS DAY. THE GLOBAL MODELS CONTINUE TO SHOW
SIGNIFICANT RUN TO RUN VARIABILITY WITH THIS WAVE, HOWEVER. AFTER
COLLABORATING WITH SOME OF THE SURROUNDING OFFICES, HAVE INTRODUCED
SOME SMALL POPS FOR RAIN OR SNOW TO CENTRAL KANSAS NEXT THURSDAY
NIGHT AND FRIDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1155 PM CST FRI DEC 19 2014
WEAK SURFACE LEE TROUGHING WILL PERSIST THROUGH THE PERIOD ON THE
HIGH PLAINS. LIGHT SOUTHWESTERLY WINDS AT 5 TO 10 KTS WILL
CONTINUE THROUGH THE TAF PERIOD BEFORE BECOMING MORE SOUTHERLY
AFTER 18Z SATURDAY. MVFR TO VFR CONDITIONS WILL PERSIST THROUGH
12Z BEFORE BECOMING VFR WITH DAYTIME HEATING BY 14-15Z. THERE IS A
CHANCE THAT STRATUS OVER THE TEXAS PANHANDLE COULD PROGRESS INTO
KDDC BY 18-19Z, WITH CIGS IN THE LOW MVFR CATEGORY GIVEN THE
SOUTHERLY WINDS TODAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 52 33 52 34 / 0 0 0 10
GCK 52 27 55 32 / 0 0 0 10
EHA 51 27 57 34 / 0 0 0 20
LBL 52 31 56 33 / 0 0 0 10
HYS 52 31 50 34 / 0 0 0 10
P28 52 37 49 36 / 0 0 10 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...FINCH
LONG TERM...GERARD
AVIATION...FINCH
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
359 AM CST SAT DEC 20 2014
...UPDATED FOR SHORT TERM DISCUSSION...
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 342 AM CST SAT DEC 20 2014
WEAK SHORTWAVE TROUGHS ARE PERIODICALLY PROGRESSING ACROSS THE
PLAINS FROM THE WEST. ONE SUCH MINOR WAVE WILL MOVE ACROSS THE
SOUTHERN PLAINS BY TONIGHT. HOWEVER, LEE TROUGHING IN RESPONSE TO
WESTERLY FLOW AT MID LEVELS SEEMS TO BE THE DOMINANT FEATURE THAT
IS AFFECTING THE LOW LEVEL WIND FIELD. EARLY MORNING SATELLITE AND
SURFACE OBSERVATIONS INDICATE LOW STRATUS ACROSS THE SOUTHERN
PLAINS AS FAR NORTH AS PERRYTON AND MEDICINE LODGE. AS SURFACE
TROUGHING ENCOURAGES SOUTHERLY WINDS TODAY, THIS LOW LEVEL
MOISTURE SHOULD PROGRESS NORTHWARD INTO LOCATIONS FROM DODGE CITY
SOUTH AND EAST TO THE OKLAHOMA BORDER. THE NAM HAS A CHARACTERISTIC
BIAS OF BEING TOO DRY AND WARM AT LOWER LEVELS IN CASES SUCH AS
THIS. THE HRRR AND RAP ARE COOLER AND INDICATE LOW CLOUD COVER
PROGRESSING AS FAR NORTH AS DODGE CITY BY EARLY AFTERNOON. CLOUD
COVER WILL TEND TO KEEP DIURNAL RANGES LOWER AND TEMPERATURES
COOLER IN THE AFTERNOON. AS AN EXAMPLE, THE TEMPERATURE AT GAGE,
OKLAHOMA STAYED 41F FROM FRIDAY AFTERNOON THROUGH EARLY THIS
MORNING AS A RESULT OF THE STRATUS. TEMPERATURES SHOULD BE WARMER
TODAY IN LOCATIONS SUCH AS SCOTT CITY AND WAKEENEY WHERE PLENTY OF
SUNSHINE IS EXPECTED. LOW STRATUS WILL PERSIST OR INCREASE IN
AREAL COVERAGE TONIGHT, AND FOG IS POSSIBLE ON THE WESTERN
PERIPHERY OF THE CLOULD SHIELD, SOME OF WHICH COULD BE LOCALLY
DENSE. THE CLOUD COVER AND HIGHER DEWPOINTS OUGHT TO KEEP
TEMPERATURES FROM FALLING A LOT TONIGHT, EXCEPT FOR WEST CENTRAL
KANSAS WHERE LESS CLOUD COVER IS EXPECTED.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 220 PM CST FRI DEC 19 2014
MEDIUM RANGE MODELS INDICATE AN OPEN UPPER LEVEL SHORTWAVE TROUGH
TRANSITIONING EASTWARD ACROSS THE CENTRAL PLAINS SUNDAY GIVING WAY
TO A NORTHWESTERLY FLOW ALOFT ACROSS THE WESTERN HIGH PLAINS BY
SUNDAY NIGHT. HOWEVER, WITH A WEAK FLOW ALOFT A LITTLE LOW/MID LEVEL
MOISTURE AVAILABLE, DRIER CONDITIONS WILL PREVAIL ACROSS WESTERN
KANSAS THROUGH SUNDAY EVENING. PRECIP CHANCES PICK UP A LITTLE EARLY
MONDAY AS A SERIES OF H5 VORT MAXIMA BEGIN TO DIG SOUTHEASTWARD OUT
OF THE NORTHERN ROCKIES INTO THE WESTERN HIGH PLAINS. MEANWHILE, AN
ASSOCIATED COLD FRONT IS PROJECTED TO PUSH INTO WESTERN KANSAS
MONDAY MORNING PROVIDING A POTENTIAL FOCUS FOR PRECIP INITIATION.
ALTHOUGH LIMITED MOISTURE AND A WEAKER FLOW ALOFT WILL LIMIT
SIGNIFICANT PRECIP CHANCES, A SLIGHT CHANCE FOR RAIN , ESPECIALLY
ACROSS EXTREME SOUTHWEST KANSAS WHERE SOME PROXIMITY TO A STRONG
UPPER LEVEL JET DIGGING ACROSS THE ROCKIES MAY BE FELT. DRY
CONDITIONS RETURN TUESDAY AS A DEVELOPING DOWNSLOPE FLOW ACROSS
WESTERN KANSAS DRAWS MUCH DRIER AIR INTO THE REGION.
ABOVE NORMAL TEMPERATURES ARE EXPECTED SUNDAY AS A LEE SIDE TROUGH
OF LOW PRESSURE DEVELOPS AND STRENGTHENS ACROSS EASTERN COLORADO.
THIS WILL SET UP A SOUTH TO SOUTHWESTERLY FLOW ACROSS WESTERN KANSAS
ENHANCING WARM AIR ADVECTION INTO THE AREA WITH H85 TEMPERATURES
CLIMBING TO A LITTLE ABOVE 5C ACROSS CENTRAL AND SOUTHWEST KANSAS.
ALONG WITH DECREASED CLOUD COVER, LOOK FOR HIGHS UP INTO THE 50S(F)
ACROSS MUCH OF THE AREA SUNDAY AFTERNOON. SIMILAR TEMPERATURES ARE
LIKELY MONDAY EVEN AS A WEAK COLD FRONT PUSHES THROUGH WESTERN
KANSAS BY MONDAY AFTERNOON. THE DELAYED ARRIVAL OF COLDER AIR BEHIND
THE FRONTAL PASSAGE WILL LOWER HIGHS BACK DOWN INTO THE 40S(F) ON
TUESDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1155 PM CST FRI DEC 19 2014
WEAK SURFACE LEE TROUGHING WILL PERSIST THROUGH THE PERIOD ON THE
HIGH PLAINS. LIGHT SOUTHWESTERLY WINDS AT 5 TO 10 KTS WILL
CONTINUE THROUGH THE TAF PERIOD BEFORE BECOMING MORE SOUTHERLY
AFTER 18Z SATURDAY. MVFR TO VFR CONDITIONS WILL PERSIST THROUGH
12Z BEFORE BECOMING VFR WITH DAYTIME HEATING BY 14-15Z. THERE IS A
CHANCE THAT STRATUS OVER THE TEXAS PANHANDLE COULD PROGRESS INTO
KDDC BY 18-19Z, WITH CIGS IN THE LOW MVFR CATEGORY GIVEN THE
SOUTHERLY WINDS TODAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 52 33 52 34 / 0 0 0 10
GCK 52 27 55 32 / 0 0 0 10
EHA 51 27 57 34 / 0 0 0 20
LBL 52 31 56 33 / 0 0 0 10
HYS 52 31 50 34 / 0 0 0 10
P28 52 37 49 36 / 0 0 10 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...FINCH
LONG TERM...JJOHNSON
AVIATION...FINCH
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1208 PM EST Sat Dec 20 2014
...Updated Aviation Discussion...
...Forecast Update...
Issued at 1025 AM EST Sat Dec 20 2014
Main forcing that brought light snow to the area this morning has
moved off into Ohio, so the remainder of the day is expected to be
dry. The afternoon forecast is largely on track, though the
challenge is cloud cover. Models are not handling the low/mid level
moisture very well at all as there is a large, although thin, deck
of clouds upstream. The HRRR seems to have a somewhat decent handle
on the current situation, so trended the forecast in that direction,
but went more pessimistic given current satellite and low sun angle
this time of year. This gives more of an cloudy/overcast afternoon
to the area, though there could be some breaks along/south of the KY
parkways. As a result of the increased clouds, lowered high
temperatures a degree or two.
Issued at 815 AM EST Sat Dec 20 2014
Radar returns, automated observations and spotter reports confirm
that the light snow continues across the Louisville metro area and
points north and east. With temperatures remaining in the upper 20s
to around 30, slick spots on untreated roads, particularly bridges
and overpasses could develop. Adjusted forecast grids and continued
SPS for portions of the area.
The main forcing for this activity is an upper level shortwave and
this is rapidly moving out of the area, so I`m expecting this
activity to end west to east over the next few hours.
Issued at 542 AM EST Sat Dec 20 2014
Light snow continues across portions of southern IN and north
central KY this morning. Some light accumulations have been reported
on cars and area roadways this morning for this activity. Updated
the grids to reflect current radar trends and issued an SPS talking
about slick spots. Still think most of this activity should move out
of the area by around sunrise.
.SHORT TERM (Now through Sunday)...
Issued at 307 AM EST Sat Dec 20 2014
Some light radar returns continue to show up across southern Indiana
and portions of north central Kentucky this morning associated with
a weak PV anomaly. Some light snow may reach the ground under
the strongest echoes, as it did here at the office. However, the
most that is expected is a very light dusting on elevated surfaces.
This activity will continue to push off to the northeast over the
next few hours and should be out of the area by sunrise.
Clouds will stick around for much of the day but should begin to
clear by late afternoon into the evening. High pressure ridging in
from the northeast will keep the area dry through Sunday. Highs
today will range from the upper 30s in the north to the mid 40s in
the south. Tomorrow will be a bit warmer with highs ranging from the
mid 40s to around 50. Lows tonight will be in the mid to upper 20s.
.LONG TERM (Sunday night through Friday)...
Issued at 332 AM EST Sat Dec 20 2014
Sunday night through Tuesday Night...
Medium range deterministic guidance continues to be in good
agreement with the overall pattern as head into the late weekend and
into early next week. The upper pattern at the beginning of the
period will feature a broad trough over the inter-mountain west with
ridging along both coasts. This will place the Ohio Valley in a
broad southwesterly flow aloft early in the period. As we move into
Monday, the multi-model consensus continues to suggest that the
ridge over the eastern Pacific will build northward into western
Canada. As this occurs, the Pacific jet will pound it`s way into
Canada and then drop into the Plains. This will lead to the broad
trough over the inter-mountain west to deepen and close off by
Monday afternoon. The trough is expected to deepen further
resulting in cyclogenesis over Texas. This surface low will deepen
as well as it heads NE into the Ohio Valley by late Tuesday night.
We`ll see dry conditions initially in our region at the beginning of
the period, but rain chances will quickly ramp up on Monday as the
broad southwesterly flow pushes quite a bit of moisture up into our
region. Precipitable water amounts of nearly 1.25 inches look to
be in our vicinity by Tuesday afternoon which is +2 standard
deviations above normal. Thus, some of the rainfall could be heavy
at times from Monday afternoon through Tuesday night. With us
remaining in the southwest flow, temperatures will be rather mild
through this portion of the forecast period. Lows Sunday night will
drop into the lower-middle 30s with highs on Monday warming into the
lower 50s in the north with lower-middle 50s across the south.
Temps will cool off just a bit Monday night with lows mainly in the
lower-mid 40s. Tuesday look like to be the mildest day of the
period with highs pushing into the upper 50s. Given the deepening
system and broad southwesterly flow, these numbers for Tuesday are
probably too conservative, and we may see some lower 60 degree
readings down across southern KY. Some colder air will start to
wrap in late Tuesday night with lows crashing into the mid 30s in
the west with mid-upper 40s in the east.
Wednesday through Friday...
...Very Active Period of Weather Likely for Christmas Eve and into
early Christmas Day...
Latest long term model guidance has been trending westward with the
overall track of the surface low. The Canadian GEM has been leading
the pack on the westward shift, and the Euro and GFS solutions have
now trended more west with the low. By Wednesday morning, low
pressure should be in east-central Kentucky with a rather large
precipitation shield encompassing much of the region. The pressure
gradient will rapidly increase during the morning hours with
sustained winds ramping up to 10-20 MPH by the early afternoon
hours. The surface low is expected to rapidly intensify during the
afternoon as it races from east-central KY into western Ontario.
Based on the multi-model consensus, we could see the system deepen
by 20+ millibars within a 24 hour period. As the low pulls away
from the region, we will see winds shift to the northwest and remain
quite elevated with sustained winds of 10-20 MPH and gusts up to
35-40 MPH. Thermal profiles are slightly warmer during the day
suggestive that much of the precipitation behind the system will be
in the form of rain. Highs early in the day will be in the upper
30s in the west to the lower-mid 40s in the east and then fall
during the afternoon.
By Christmas Eve, we will see temperature profiles crash from west
to east resulting in a quick change over to snow showers. Very
blustery and cold conditions look increasingly likely for Christmas
eve with widespread snow shower activity in progress across the
region. Model soundings continue to show very steep low-level lapse
rates with plenty of moisture in the ice crystal producing layer.
Thus, some snow showers may capable of producing moderate snow at
times during the evening. While temperatures drop to near freezing,
there will be an opportunity for some minor accumulations. Given
the relatively warm ground and recent rainfall, any snowfall
accumulation will be dependent upon the intensity of the snow
showers.
The models continue to trend a little faster with the moisture pull
off to the northeast early Christmas morning. Current thinking is
that we`ll still have some snow shower activity past midnight, but
then rapidly diminish by sunrise. The flow aloft looks to quickly
revert back to zonal flow which will likely push some drier air into
the region resulting clearing skies during the day. Temperatures
will be challenging depending on how fast skies clear. The clear
trend in the models has been warmer, so we have adjusted
temperatures slightly upwards with highs in the upper 30s in the
north to the lower-mid 40s across the south.
Generally dry conditions are expected for Friday. However, another
quick moving system will be pushing into the region by the late part
of the period. Temps on Friday may be quite mild within the return
flow regime with upper 40s to lower 50s being possible. A period of
rain showers looks increasingly likely for Friday night with colder
conditions returning by Saturday.
&&
.AVIATION (18Z TAF Update)...
Issued at 1204 PM EST Sat Dec 20 2014
Much of the area around SDF/LEX/BWG remains VFR at this hour with
2000-2500 ft MVFR ceilings across southern Indiana and southwest
Ohio. Expecting VFR clouds to persist through the period with
light/variable winds this evening becoming more northeasterly to
easterly overnight. There are some indications that clouds could
scatter out overnight into Sunday morning, especially at BWG. Less
confident at SDF/LEX. If clouds do scatter out, the baggy wind field
and residual low-level moisture could result in light fog.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Update.........ZBT
Short Term.....EER
Long Term......MJ
Aviation.......ZBT
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1028 AM EST Sat Dec 20 2014
...Forecast Update...
Issued at 1025 AM EST Sat Dec 20 2014
Main forcing that brought light snow to the area this morning has
moved off into Ohio, so the remainder of the day is expected to be
dry. The afternoon forecast is largely on track, though the
challenge is cloud cover. Models are not handling the low/mid level
moisture very well at all as there is a large, although thin, deck
of clouds upstream. The HRRR seems to have a somewhat decent handle
on the current situation, so trended the forecast in that direction,
but went more pessimistic given current satellite and low sun angle
this time of year. This gives more of an cloudy/overcast afternoon
to the area, though there could be some breaks along/south of the KY
parkways. As a result of the increased clouds, lowered high
temperatures a degree or two.
Issued at 815 AM EST Sat Dec 20 2014
Radar returns, automated observations and spotter reports confirm
that the light snow continues across the Louisville metro area and
points north and east. With temperatures remaining in the upper 20s
to around 30, slick spots on untreated roads, particularly bridges
and overpasses could develop. Adjusted forecast grids and continued
SPS for portions of the area.
The main forcing for this activity is an upper level shortwave and
this is rapidly moving out of the area, so I`m expecting this
activity to end west to east over the next few hours.
Issued at 542 AM EST Sat Dec 20 2014
Light snow continues across portions of southern IN and north
central KY this morning. Some light accumulations have been reported
on cars and area roadways this morning for this activity. Updated
the grids to reflect current radar trends and issued an SPS talking
about slick spots. Still think most of this activity should move out
of the area by around sunrise.
.SHORT TERM (Now through Sunday)...
Issued at 307 AM EST Sat Dec 20 2014
Some light radar returns continue to show up across southern Indiana
and portions of north central Kentucky this morning associated with
a weak PV anomaly. Some light snow may reach the ground under
the strongest echoes, as it did here at the office. However, the
most that is expected is a very light dusting on elevated surfaces.
This activity will continue to push off to the northeast over the
next few hours and should be out of the area by sunrise.
Clouds will stick around for much of the day but should begin to
clear by late afternoon into the evening. High pressure ridging in
from the northeast will keep the area dry through Sunday. Highs
today will range from the upper 30s in the north to the mid 40s in
the south. Tomorrow will be a bit warmer with highs ranging from the
mid 40s to around 50. Lows tonight will be in the mid to upper 20s.
.LONG TERM (Sunday night through Friday)...
Issued at 332 AM EST Sat Dec 20 2014
Sunday night through Tuesday Night...
Medium range deterministic guidance continues to be in good
agreement with the overall pattern as head into the late weekend and
into early next week. The upper pattern at the beginning of the
period will feature a broad trough over the inter-mountain west with
ridging along both coasts. This will place the Ohio Valley in a
broad southwesterly flow aloft early in the period. As we move into
Monday, the multi-model consensus continues to suggest that the
ridge over the eastern Pacific will build northward into western
Canada. As this occurs, the Pacific jet will pound it`s way into
Canada and then drop into the Plains. This will lead to the broad
trough over the inter-mountain west to deepen and close off by
Monday afternoon. The trough is expected to deepen further
resulting in cyclogenesis over Texas. This surface low will deepen
as well as it heads NE into the Ohio Valley by late Tuesday night.
We`ll see dry conditions initially in our region at the beginning of
the period, but rain chances will quickly ramp up on Monday as the
broad southwesterly flow pushes quite a bit of moisture up into our
region. Precipitable water amounts of nearly 1.25 inches look to
be in our vicinity by Tuesday afternoon which is +2 standard
deviations above normal. Thus, some of the rainfall could be heavy
at times from Monday afternoon through Tuesday night. With us
remaining in the southwest flow, temperatures will be rather mild
through this portion of the forecast period. Lows Sunday night will
drop into the lower-middle 30s with highs on Monday warming into the
lower 50s in the north with lower-middle 50s across the south.
Temps will cool off just a bit Monday night with lows mainly in the
lower-mid 40s. Tuesday look like to be the mildest day of the
period with highs pushing into the upper 50s. Given the deepening
system and broad southwesterly flow, these numbers for Tuesday are
probably too conservative, and we may see some lower 60 degree
readings down across southern KY. Some colder air will start to
wrap in late Tuesday night with lows crashing into the mid 30s in
the west with mid-upper 40s in the east.
Wednesday through Friday...
...Very Active Period of Weather Likely for Christmas Eve and into
early Christmas Day...
Latest long term model guidance has been trending westward with the
overall track of the surface low. The Canadian GEM has been leading
the pack on the westward shift, and the Euro and GFS solutions have
now trended more west with the low. By Wednesday morning, low
pressure should be in east-central Kentucky with a rather large
precipitation shield encompassing much of the region. The pressure
gradient will rapidly increase during the morning hours with
sustained winds ramping up to 10-20 MPH by the early afternoon
hours. The surface low is expected to rapidly intensify during the
afternoon as it races from east-central KY into western Ontario.
Based on the multi-model consensus, we could see the system deepen
by 20+ millibars within a 24 hour period. As the low pulls away
from the region, we will see winds shift to the northwest and remain
quite elevated with sustained winds of 10-20 MPH and gusts up to
35-40 MPH. Thermal profiles are slightly warmer during the day
suggestive that much of the precipitation behind the system will be
in the form of rain. Highs early in the day will be in the upper
30s in the west to the lower-mid 40s in the east and then fall
during the afternoon.
By Christmas Eve, we will see temperature profiles crash from west
to east resulting in a quick change over to snow showers. Very
blustery and cold conditions look increasingly likely for Christmas
eve with widespread snow shower activity in progress across the
region. Model soundings continue to show very steep low-level lapse
rates with plenty of moisture in the ice crystal producing layer.
Thus, some snow showers may capable of producing moderate snow at
times during the evening. While temperatures drop to near freezing,
there will be an opportunity for some minor accumulations. Given
the relatively warm ground and recent rainfall, any snowfall
accumulation will be dependent upon the intensity of the snow
showers.
The models continue to trend a little faster with the moisture pull
off to the northeast early Christmas morning. Current thinking is
that we`ll still have some snow shower activity past midnight, but
then rapidly diminish by sunrise. The flow aloft looks to quickly
revert back to zonal flow which will likely push some drier air into
the region resulting clearing skies during the day. Temperatures
will be challenging depending on how fast skies clear. The clear
trend in the models has been warmer, so we have adjusted
temperatures slightly upwards with highs in the upper 30s in the
north to the lower-mid 40s across the south.
Generally dry conditions are expected for Friday. However, another
quick moving system will be pushing into the region by the late part
of the period. Temps on Friday may be quite mild within the return
flow regime with upper 40s to lower 50s being possible. A period of
rain showers looks increasingly likely for Friday night with colder
conditions returning by Saturday.
&&
.AVIATION (12Z TAF Update)...
Issued at 550 AM EST Sat Dec 20 2014
Some very light snow or flurries may move through SDF and LEX over
the next couple of hours. Thereafter, dry conditions are expected
through the TAF period. Skies will be cloudy through most of the day
but ceilings should remain mainly VFR. Clouds may begin to scatter
out late this afternoon into this evening. Winds will be light and
out of the north today. They will become variable to calm overnight.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Update.........ZBT
Short Term.....EER
Long Term......MJ
Aviation.......EER
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
129 PM EST SAT DEC 20 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 434 AM EST SAT DEC 20 2014
WV LOOP AND 00Z RAOBS SHOW A LARGE SCALE ZONAL FLOW...BUT THERE IS
EMBEDDED AMPLIFICATION. TROUGHING WAS AS CLOSE BY AS NORTHERN PLAINS
AND MINNESOTA THIS MORNING. PRIMARY PV ANAMOLIES/SHORTWAVES WITHIN
TROUGH WERE OVER FAR NORTHWEST ONTARIO AND OVER WESTERN IOWA. WEAK
SFC TROUGH NOTED OVER WESTERN MINNESOTA TOO...WHILE SFC RIDGING
EXTENDING OUT OF QUEBEC WAS STILL MAIN FEATURE OVER GREAT LAKES. THE
ONTARIO WAVE AND WEAK WARM AIR ADVECTION AHEAD OF THE MINNESOTA
TROUGH AND UPSLOPE LOW-LEVEL FLOW IS SUPPORTING LGT WINTRY MIX OF
SNOW AND FREEZING DRIZZLE OVER NORTHERN MINNESOTA THIS MORNING. ONLY
AFFECT FM ONTARIO SHORTWAVE OVER UPR MICHIGAN IS BATCH OF MID CLOUDS
OVER WEST HALF OF CWA. NO PRECIP THROUGH. ONLY WEATHER OF NOTE IN
THE CWA THIS MORNING IS PATCHY DENSE FOG OVER CNTRL CWA...VCNTY OF
IMT TO SAW.
ONTARIO WAVE MOVES LITTLE EASTWARD TODAY AS ANOTHER SHORTWAVE
CURRENTLY OVER MT TRIES TO CATCH UP WITH IT. THUS...SFC TROUGH AND
WARM AIR ADVECTION STAY MAINLY OVER MN. RAP SHOWS WEAK LIFT TRYING
TO IMPACT KEWEENAW THIS MORNING INTO EARLY AFTN...BUT IT LOOKS MUCH
DRIER THAN IT IS UPSTREAM OVER MN WHERE PRECIP IN OCCURRING THIS
MORNING...SO NOT EXPECTING ANY PRECIP OUT OF THIS FOR OUR AREA. LOW
CLOUDS OVER NW WI AND WEST UPR MICHIGAN GRADUALLY EASE
EASTWARD...BUT A FEW SPOTS IN EAST HALF OF CWA MAY STAY CLEAR OF THE
LOW CLOUDS ALL DAY. TOUGH TO SAY EXACTLY WHERE THOUGH AS THERE ARE
DIFFERENT AREAS OF CLOUDS AFFECTING THE AREA AND MODELS FORECASTING
OF THEM IS ONLY FAIR. FOR TEMPS...WENT AT OR 1-2 DEGREES ABOVE
FRIDAY READINGS AS 925MB TEMPS WARM SLIGHTLY COMPARED TO FRIDAY.
WHERE SUNSHINE CAN PERSIST INTO THE AFTN...TEMPS COULD BUMP INTO THE
MID 30S. BEST SHOT AT THAT WOULD BE EAST CENTRAL CWA...VCTY OF
MUNISING AND GRAND MARAIS. FARTHER WEST...CLOUDS WILL HOLD TEMPS
DOWN OVER INTERIOR WEST TO UPR 20S. INTO THIS EVENING...EXPECT LOW
CLOUDS /HIGHER 925MB-850MB RH/ TO BE OVER WEST HALF OF CWA AND ALSO
THE FAR EAST CWA. EVENTUALLY THOUGH...CLOUDS SHOULD FILL IN OVER ALL
CWA. UNTIL THAT OCCURS...TEMPS FOR INTERIOR CNTRL CWA OR AT LEAST
PORTIONS OF THESE AREAS MAY DROP OFF QUICKLY. CLOSEST MODEL TO
INCICATE THAT WAS BIAS CORRECTED NAM MOS. TWEAKED DOWN EVEN FURTHER
THOUGH /LOW TEENS/ SEEING HOW MUCH TEMPS FELL EARLY THIS MORNING
WHERE SKIES WERE CLEAR. ALSO WILL ADD FOG TO THOSE AREAS SINCE THESE
TEMPS WILL BE WELL BELOW THE EXPECTED AFTN DWPNTS. WHERE CLOUDS STAY
IN ALL NIGHT...MIN TEMPS LIKELY STAY ABOVE 20 DEGREES.
SOUNDINGS FM NAM AND GFS INDICATE INCREASING SUB 950MB MOISTURE
LATE TONIGHT FM THE SOUTH AND WITH UPSLOPE SOUTH FLOW OVER CNTRL
CWA COULD SEE PATCHY FREEZING DRIZZLE IMT TO NEGAUNEE. NOT MUCH UVM
SHOWN ON THE SOUNDINGS THOUGH...SO LEFT IT OUT OF GRIDS ATTM.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 434 AM EST SAT DEC 20 2014
MAIN FOCUS FOR THE LONGER TERM REMAINS THE POTENTIAL FOR SOME SN OR
MIXED PCPN IN THE MON INTO XMAS PERIOD ASSOCIATED WITH A DEEPENING
UPR TROF IN THE CENTRAL CONUS AS A SERIES OF SHRTWVS RIDING OVER A
MEAN RDG ALONG THE W COAST DIG INTO THE PLAINS. THE STRONGEST OF
THESE DISTURBANCE IS NOW OVER THE NE PACIFIC OCEAN. ALTHOUGH THE
MODELS ARE COMING INTO BETTER AGREEMENT ON WARMER LLVL TEMPS IN THE
TUE/WED TIME AND ON THE DEVELOPMENT OF A LO PRES IN THE LO/MID MS
RIVER VALLEY THAT WL TRACK SOMEWHERE NEAR THE CENTRAL GREAT LKS ON
WED AND INTO CANADA ON XMAS DAY...THERE ARE STILL SOME SIGNIFICANT
DIFFERENCES ON THE DETAILS OF HOW THE INTERACTION/PHASING BTWN THESE
SEPARATE DISTURBANCES THAT ARE STILL OVER THE DATA POOR PACIFIC WL
IMPACT THE SFC LO TRACK AND UPR MI.
SUN/SUN NIGHT...AS LLVL S WIND BTWN DEPARTING HI PRES IN SE CANADA
AND FALLING MSLP TO THE W ADVECT MOISTER LLVL AIR INTO THE CWA...
OPTED TO INCLUCE SOME FREEZING DZ OVER THE SCENTRAL IN THE MRNG
WHERE LLVL WIND WL UPSLOPE OFF LK MI. THEN OPERATIONAL MODELS SHOW A
SHRTWV MOVING E FM THE NRN PLAINS ACROSS THE NW GREAT LKS AND INTO
NW ONTARIO BY 12Z MON... BRINGING A PERIOD OF DEEP LYR QVECTOR CNVGC
ASSOCIATED WITH SOME DPVA AND ISENTROPIC ASCENT BEST DEPICTED ON THE
285-290K SFCS /ABOUT H85-75/ IN THE STRONGER SSW FLOW BTWN HI PRES
OVER THE CNDN MARITIMES AND LO PRES IN THE NRN PLAINS. ARRIVAL OF
THE DEEPER MSTR SHOULD END THE FREEZING DZ. THE BULK OF THE GUIDANCE
INDICATES THE ACCOMPANYING SN WL BEGIN OVER THE SCENTRAL SUN AFTN
AND THEN OVERSPREAD THE REST OF THE FA THRU SUN NGT. THE NAM SHOWS
THE HIEST QPF UP TO 0.25-0.30 INCH OVER THE SCENTRAL...WHERE THE
NEAR SFC SSE FLOW WL UPSLOPE OFF LK MI AND H85 MSTR CNVGC IS A BIT
SHARPER. THE GFS ON THE OTHER HAND SHIFTS THE HIER QPF TO OVER THE
NW CWA LATE AT NGT. GIVEN THE GREATER CONSISTENCY OF THE NAM WITH
PREVIOUS FCST GUIDANCE...TENDED TOWARD THAT MODEL SCENARIO. WL BUMP
POPS UP TO LIKELY OVER THE SCENTRAL CENTERED ARND SUN EVNG WHEN THE
FORCING WL BE GREATEST. THERE COULD BE A FEW INCHES OF SN ACCUM IN
THIS AREA AS WELL. SSW FLOW UP THE LENGTH OF LK MI MAY SUPPORT SOME
HIER POPS OVER THE E...BUT MARGINAL CHILL OF THE AIRMASS FOR LK
ENHANCEMENT WITH H85 TEMPS RISING TO -5C BY 00Z MON SHOULD LIMIT THE
POTENTIAL FOR A SGNFT IMPACT. TEMPS WL REMAIN ABOVE NORMAL...
ESPECIALLY ON SUN NGT WITH CLD COVER AND A STEADY S WIND GREATLY
LIMITING THE DIURNAL TEMP FALL.
MON...FOLLOWING THE EXIT OF THE SHRTWV INTO NW ONTARIO ON MON AND
THE ARRIVAL OF SOME MID LVL DRYING ASSOCIATED WITH A SHRTWV RDG AXIS
ROTATING NEWD THRU THE NW GREAT LKS TO THE E OF THE DEEPENING UPR
TROF IN THE PLAINS...EXPECT DIMINISHED POPS. BUT PERSISTENT WAA IN
THE DEEP S FLOW BTWN LO PRES SLIDING SEWD THRU THE NRN PLAINS AND HI
PRES OVER THE CNDN MARITIMES WL CAUSE LOTS OF CLDS AND CONTINUED LO
CHC POPS. AS THE LLVLS WARM INTO THE 30S ESPECIALLY NEAR THE WARMING
INFLUENCE OF THE GREAT LKS...LIGHT PCPN MAY INCLUDE A MIX OF RA AND
SN.
MON NGT/TUE...THE 00Z GFS REMAINS CONSISTENT ON SHOWING A CLOSED H5
LO WITHIN THE DEEPENING CENTRAL CONUS TROF/DEEPER SFC LO PRES MOVING
INTO THE UPR LKS DURING THIS TIME ALONG WITH HIER H85 TEMPS UP TO
ARND 0C. THE 12Z/00Z ECMWF MODELS ON THE OTHER HAND HOLD THE CLOSED
H5 LO/SFC LO FARTHER TO THE SW...WITH A SLOWER ARRIVAL OF DEEPER
MSTR AND LOWER H85 TEMPS. BOTH MODELS SHOW DISTURBANCES DIGGING SEWD
TO THE E OF THE UPR RDG ACROSS THE W DEEPENING THE PLAINS TROF.
SINCE THIS GREATER FORCING INTO THE SRN PLAINS SHOULD TEND TO HOLD
THE CLOSED LO THE SW...WL TEND TOWARD THE 12Z ECMWF SCENARIO. THIS
MODEL SHOWS DEEPER MSTR ARRIVING LATE MON NGT AND PERSISTING THRU
TUE AS THE WEAKER SHRTWV LIFTS NEWD AWAY FM CLOSED LO TO THE SW.
ALTHOUGH THE 00Z ECMWF H85 TEMPS ARE LOWER THAN FCST BY THE GFS...
THE FCST H100-85 THKNS IS ONLY A BIT LOWER THAN THE GFS FCST. A LOOK
AT THE 00Z ECMWF FCST SDNGS SHOW A TREND TOWARD A WARMER NEAR SFC
LYR THAT WOULD SUPPORT MORE RA...AS SHOWN BY RECENT GFS RUNS. SO
TENDED TO RAISE FCST TEMPS AND INCLUDE A GREATER AREA OF AT LEAST A
MIX WITH RA. THE FCST SDNGS FM NEITHER MODEL SHOW AN ELEVATED WARM
LYR...SO THE PCPN SHOULD BE RA OR SN. ADDED A MENTION OF SOME FOG
DURING THE MON NIGHT/TUE TIME TO REFLECT THE RA/HIER TEMPS AND
DEWPTS OVER A MELTING SN PACK AT MANY LOCATIONS THAT UPSLOPE OFF LK
MI IN THE EXPECTED LLVL SE FLOW. THIS MIXED PCPN WL TEND TO DIMINISH
ON TUE NGT AS SOME UPR DRYING FOLLOWS THE SHRTWV EXITING NNEWD INTO
ONTARIO.
WED/THU...THE LONGER RANGE MODELS ARE BEGINNING TO COME INTO BETTER
AGREEMENT ON SHOWING A SECOND LO DVLPG IN THE LOWER TO MID MS RIVER
VALLEY ON TUE AT THE SRN END OF THE DEEPING CENTRAL CONUS TROF AND
THEN MOVING NNE INTO THE CENTRAL GREAT LKS ON WED AND THEN INTO ERN
ONTARIO ON XMAS DAY WHILE DEEPENING SIGNIFICANTLY AS THE UPR TROF
TAKES ON A MORE NEGATIVE TILT. NOT SURPRISINGLY...THE EXACT TRACK OF
THE SFC LO...WHICH WL MAKE A SGNFT DIFFERNCE ON PTYPE/PCPN TOTALS
OVER UPR MI...IS STILL UNCERTAIN. THE 00Z GFS INDICATES A FARTHER W
TRACK ACROSS THE ERN U.P. THAN THE 00Z ECMWF/UKMET RUNS...BUT THE
GFS INDICATES THE PCPN WOULD BE HEAVY SN OVER THE W HALF OF UPR MI.
THE FARTHER E ECMWF MODEL GENERATES MUCH LIGHT PCPN OVER THE E.
CONSIDERING THE SGNFT DIFFERNCES THAT REMAIN...RELIED ON THE MODEL
CONSENSUS FOR THE FCST DETAILS. THIS CONSENSUS SUPPORTS HIER POPS
OVER THE E WITH A CHANGE IN PTYPE FM MIXED RA/SN TO MAINLY SN AS THE
INCREASING N BACKING NW WINDS ADVECT COLDER AIR INTO THE CWA.
IN THE WAKE OF THE DEEPENING LO MOVING INTO ONTARIO ON XMAS DAY...
THE PRES GRADIENT IS PROGGED TO TIGTHEN SGNFTLY AND H925 WINDS
INCREASE TO NEAR 45 KTS. NW WIND GUSTS MAY AT LEAST APRCH ADVY
CRITERIA...ESPECIALLY AT EXPOSED LOCATIONS NEAR LK SUP.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 129 PM EST SAT DEC 20 2014
MVFR CEILINGS AND VIS SHOULD BE THE RULE THROUGH THE PERIOD. LIGHT S
WINDS WILL BE ON THE INCREASE DURING THE DAY SUNDAY...BUT REMAIN
AROUND 10KTS OR LESS THROUGH 18Z. THIS WILL BE IN RESPONSE TO THE
LARGE AREA OF HIGH PRESSURE TO OUR E CONTINUING TO EXIT TO E QUEBEC
AND THE NEW ENGLAND STATES. ON SUNDAY THE NEXT LOW PRESSURE SYSTEM
WILL BE NEARING FROM ALBERTA/SASKATCHEWAN/MONTANA.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 434 AM EST SAT DEC 20 2014
EXPECT S WINDS UNDER 20 KTS ASSOCIATED WITH HI PRES DRIFTING E THRU
SE CANADA TO PERSIST INTO SUN. THE S WINDS WILL INCREASE UP TO 25
KTS OVER AT LEAST THE E HALF OF THE LAKE ON SUN INTO MON AS A LO
PRES TRACKS E THRU THE NORTHERN PLAINS AND THE PRES GRADIENT
TIGHTENS OVER THE UPPER LAKES. AS ANOTHER LO PRES DEVELOPS TO THE S
ON TUE...THE FLOW WILL TEND TO BACK TOWARD THE NW. THE LATEST TRENDS
INDICATE THIS LO WILL DEEPEN SIGNFICANTLY AS IT MOVES TO THE NNE
THRU THE CENTRAL GREAT LAKES ON WED AND INTO SE ONTARIO ON XMAS DAY.
THE POTENTIAL FOR A N VEERING NW GALE EVENT FROM LATE ON WED THRU
XMAS DAY NOW LOOKS GREATER.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLA
LONG TERM...KC
AVIATION...KF
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
654 AM EST SAT DEC 20 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 434 AM EST SAT DEC 20 2014
WV LOOP AND 00Z RAOBS SHOW A LARGE SCALE ZONAL FLOW...BUT THERE IS
EMBEDDED AMPLIFICATION. TROUGHING WAS AS CLOSE BY AS NORTHERN PLAINS
AND MINNESOTA THIS MORNING. PRIMARY PV ANAMOLIES/SHORTWAVES WITHIN
TROUGH WERE OVER FAR NORTHWEST ONTARIO AND OVER WESTERN IOWA. WEAK
SFC TROUGH NOTED OVER WESTERN MINNESOTA TOO...WHILE SFC RIDGING
EXTENDING OUT OF QUEBEC WAS STILL MAIN FEATURE OVER GREAT LAKES. THE
ONTARIO WAVE AND WEAK WARM AIR ADVECTION AHEAD OF THE MINNESOTA
TROUGH AND UPSLOPE LOW-LEVEL FLOW IS SUPPORTING LGT WINTRY MIX OF
SNOW AND FREEZING DRIZZLE OVER NORTHERN MINNESOTA THIS MORNING. ONLY
AFFECT FM ONTARIO SHORTWAVE OVER UPR MICHIGAN IS BATCH OF MID CLOUDS
OVER WEST HALF OF CWA. NO PRECIP THROUGH. ONLY WEATHER OF NOTE IN
THE CWA THIS MORNING IS PATCHY DENSE FOG OVER CNTRL CWA...VCNTY OF
IMT TO SAW.
ONTARIO WAVE MOVES LITTLE EASTWARD TODAY AS ANOTHER SHORTWAVE
CURRENTLY OVER MT TRIES TO CATCH UP WITH IT. THUS...SFC TROUGH AND
WARM AIR ADVECTION STAY MAINLY OVER MN. RAP SHOWS WEAK LIFT TRYING
TO IMPACT KEWEENAW THIS MORNING INTO EARLY AFTN...BUT IT LOOKS MUCH
DRIER THAN IT IS UPSTREAM OVER MN WHERE PRECIP IN OCCURRING THIS
MORNING...SO NOT EXPECTING ANY PRECIP OUT OF THIS FOR OUR AREA. LOW
CLOUDS OVER NW WI AND WEST UPR MICHIGAN GRADUALLY EASE
EASTWARD...BUT A FEW SPOTS IN EAST HALF OF CWA MAY STAY CLEAR OF THE
LOW CLOUDS ALL DAY. TOUGH TO SAY EXACTLY WHERE THOUGH AS THERE ARE
DIFFERENT AREAS OF CLOUDS AFFECTING THE AREA AND MODELS FORECASTING
OF THEM IS ONLY FAIR. FOR TEMPS...WENT AT OR 1-2 DEGREES ABOVE
FRIDAY READINGS AS 925MB TEMPS WARM SLIGHTLY COMPARED TO FRIDAY.
WHERE SUNSHINE CAN PERSIST INTO THE AFTN...TEMPS COULD BUMP INTO THE
MID 30S. BEST SHOT AT THAT WOULD BE EAST CENTRAL CWA...VCTY OF
MUNISING AND GRAND MARAIS. FARTHER WEST...CLOUDS WILL HOLD TEMPS
DOWN OVER INTERIOR WEST TO UPR 20S. INTO THIS EVENING...EXPECT LOW
CLOUDS /HIGHER 925MB-850MB RH/ TO BE OVER WEST HALF OF CWA AND ALSO
THE FAR EAST CWA. EVENTUALLY THOUGH...CLOUDS SHOULD FILL IN OVER ALL
CWA. UNTIL THAT OCCURS...TEMPS FOR INTERIOR CNTRL CWA OR AT LEAST
PORTIONS OF THESE AREAS MAY DROP OFF QUICKLY. CLOSEST MODEL TO
INCICATE THAT WAS BIAS CORRECTED NAM MOS. TWEAKED DOWN EVEN FURTHER
THOUGH /LOW TEENS/ SEEING HOW MUCH TEMPS FELL EARLY THIS MORNING
WHERE SKIES WERE CLEAR. ALSO WILL ADD FOG TO THOSE AREAS SINCE THESE
TEMPS WILL BE WELL BELOW THE EXPECTED AFTN DWPNTS. WHERE CLOUDS STAY
IN ALL NIGHT...MIN TEMPS LIKELY STAY ABOVE 20 DEGREES.
SOUNDINGS FM NAM AND GFS INDICATE INCREASING SUB 950MB MOISTURE
LATE TONIGHT FM THE SOUTH AND WITH UPSLOPE SOUTH FLOW OVER CNTRL
CWA COULD SEE PATCHY FREEZING DRIZZLE IMT TO NEGAUNEE. NOT MUCH UVM
SHOWN ON THE SOUNDINGS THOUGH...SO LEFT IT OUT OF GRIDS ATTM.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 434 AM EST SAT DEC 20 2014
MAIN FOCUS FOR THE LONGER TERM REMAINS THE POTENTIAL FOR SOME SN OR
MIXED PCPN IN THE MON INTO XMAS PERIOD ASSOCIATED WITH A DEEPENING
UPR TROF IN THE CENTRAL CONUS AS A SERIES OF SHRTWVS RIDING OVER A
MEAN RDG ALONG THE W COAST DIG INTO THE PLAINS. THE STRONGEST OF
THESE DISTURBANCE IS NOW OVER THE NE PACIFIC OCEAN. ALTHOUGH THE
MODELS ARE COMING INTO BETTER AGREEMENT ON WARMER LLVL TEMPS IN THE
TUE/WED TIME AND ON THE DEVELOPMENT OF A LO PRES IN THE LO/MID MS
RIVER VALLEY THAT WL TRACK SOMEWHERE NEAR THE CENTRAL GREAT LKS ON
WED AND INTO CANADA ON XMAS DAY...THERE ARE STILL SOME SIGNIFICANT
DIFFERENCES ON THE DETAILS OF HOW THE INTERACTION/PHASING BTWN THESE
SEPARATE DISTURBANCES THAT ARE STILL OVER THE DATA POOR PACIFIC WL
IMPACT THE SFC LO TRACK AND UPR MI.
SUN/SUN NIGHT...AS LLVL S WIND BTWN DEPARTING HI PRES IN SE CANADA
AND FALLING MSLP TO THE W ADVECT MOISTER LLVL AIR INTO THE CWA...
OPTED TO INCLUCE SOME FREEZING DZ OVER THE SCENTRAL IN THE MRNG
WHERE LLVL WIND WL UPSLOPE OFF LK MI. THEN OPERATIONAL MODELS SHOW A
SHRTWV MOVING E FM THE NRN PLAINS ACROSS THE NW GREAT LKS AND INTO
NW ONTARIO BY 12Z MON... BRINGING A PERIOD OF DEEP LYR QVECTOR CNVGC
ASSOCIATED WITH SOME DPVA AND ISENTROPIC ASCENT BEST DEPICTED ON THE
285-290K SFCS /ABOUT H85-75/ IN THE STRONGER SSW FLOW BTWN HI PRES
OVER THE CNDN MARITIMES AND LO PRES IN THE NRN PLAINS. ARRIVAL OF
THE DEEPER MSTR SHOULD END THE FREEZING DZ. THE BULK OF THE GUIDANCE
INDICATES THE ACCOMPANYING SN WL BEGIN OVER THE SCENTRAL SUN AFTN
AND THEN OVERSPREAD THE REST OF THE FA THRU SUN NGT. THE NAM SHOWS
THE HIEST QPF UP TO 0.25-0.30 INCH OVER THE SCENTRAL...WHERE THE
NEAR SFC SSE FLOW WL UPSLOPE OFF LK MI AND H85 MSTR CNVGC IS A BIT
SHARPER. THE GFS ON THE OTHER HAND SHIFTS THE HIER QPF TO OVER THE
NW CWA LATE AT NGT. GIVEN THE GREATER CONSISTENCY OF THE NAM WITH
PREVIOUS FCST GUIDANCE...TENDED TOWARD THAT MODEL SCENARIO. WL BUMP
POPS UP TO LIKELY OVER THE SCENTRAL CENTERED ARND SUN EVNG WHEN THE
FORCING WL BE GREATEST. THERE COULD BE A FEW INCHES OF SN ACCUM IN
THIS AREA AS WELL. SSW FLOW UP THE LENGTH OF LK MI MAY SUPPORT SOME
HIER POPS OVER THE E...BUT MARGINAL CHILL OF THE AIRMASS FOR LK
ENHANCEMENT WITH H85 TEMPS RISING TO -5C BY 00Z MON SHOULD LIMIT THE
POTENTIAL FOR A SGNFT IMPACT. TEMPS WL REMAIN ABOVE NORMAL...
ESPECIALLY ON SUN NGT WITH CLD COVER AND A STEADY S WIND GREATLY
LIMITING THE DIURNAL TEMP FALL.
MON...FOLLOWING THE EXIT OF THE SHRTWV INTO NW ONTARIO ON MON AND
THE ARRIVAL OF SOME MID LVL DRYING ASSOCIATED WITH A SHRTWV RDG AXIS
ROTATING NEWD THRU THE NW GREAT LKS TO THE E OF THE DEEPENING UPR
TROF IN THE PLAINS...EXPECT DIMINISHED POPS. BUT PERSISTENT WAA IN
THE DEEP S FLOW BTWN LO PRES SLIDING SEWD THRU THE NRN PLAINS AND HI
PRES OVER THE CNDN MARITIMES WL CAUSE LOTS OF CLDS AND CONTINUED LO
CHC POPS. AS THE LLVLS WARM INTO THE 30S ESPECIALLY NEAR THE WARMING
INFLUENCE OF THE GREAT LKS...LIGHT PCPN MAY INCLUDE A MIX OF RA AND
SN.
MON NGT/TUE...THE 00Z GFS REMAINS CONSISTENT ON SHOWING A CLOSED H5
LO WITHIN THE DEEPENING CENTRAL CONUS TROF/DEEPER SFC LO PRES MOVING
INTO THE UPR LKS DURING THIS TIME ALONG WITH HIER H85 TEMPS UP TO
ARND 0C. THE 12Z/00Z ECMWF MODELS ON THE OTHER HAND HOLD THE CLOSED
H5 LO/SFC LO FARTHER TO THE SW...WITH A SLOWER ARRIVAL OF DEEPER
MSTR AND LOWER H85 TEMPS. BOTH MODELS SHOW DISTURBANCES DIGGING SEWD
TO THE E OF THE UPR RDG ACROSS THE W DEEPENING THE PLAINS TROF.
SINCE THIS GREATER FORCING INTO THE SRN PLAINS SHOULD TEND TO HOLD
THE CLOSED LO THE SW...WL TEND TOWARD THE 12Z ECMWF SCENARIO. THIS
MODEL SHOWS DEEPER MSTR ARRIVING LATE MON NGT AND PERSISTING THRU
TUE AS THE WEAKER SHRTWV LIFTS NEWD AWAY FM CLOSED LO TO THE SW.
ALTHOUGH THE 00Z ECMWF H85 TEMPS ARE LOWER THAN FCST BY THE GFS...
THE FCST H100-85 THKNS IS ONLY A BIT LOWER THAN THE GFS FCST. A LOOK
AT THE 00Z ECMWF FCST SDNGS SHOW A TREND TOWARD A WARMER NEAR SFC
LYR THAT WOULD SUPPORT MORE RA...AS SHOWN BY RECENT GFS RUNS. SO
TENDED TO RAISE FCST TEMPS AND INCLUDE A GREATER AREA OF AT LEAST A
MIX WITH RA. THE FCST SDNGS FM NEITHER MODEL SHOW AN ELEVATED WARM
LYR...SO THE PCPN SHOULD BE RA OR SN. ADDED A MENTION OF SOME FOG
DURING THE MON NIGHT/TUE TIME TO REFLECT THE RA/HIER TEMPS AND
DEWPTS OVER A MELTING SN PACK AT MANY LOCATIONS THAT UPSLOPE OFF LK
MI IN THE EXPECTED LLVL SE FLOW. THIS MIXED PCPN WL TEND TO DIMINISH
ON TUE NGT AS SOME UPR DRYING FOLLOWS THE SHRTWV EXITING NNEWD INTO
ONTARIO.
WED/THU...THE LONGER RANGE MODELS ARE BEGINNING TO COME INTO BETTER
AGREEMENT ON SHOWING A SECOND LO DVLPG IN THE LOWER TO MID MS RIVER
VALLEY ON TUE AT THE SRN END OF THE DEEPING CENTRAL CONUS TROF AND
THEN MOVING NNE INTO THE CENTRAL GREAT LKS ON WED AND THEN INTO ERN
ONTARIO ON XMAS DAY WHILE DEEPENING SIGNIFICANTLY AS THE UPR TROF
TAKES ON A MORE NEGATIVE TILT. NOT SURPRISINGLY...THE EXACT TRACK OF
THE SFC LO...WHICH WL MAKE A SGNFT DIFFERNCE ON PTYPE/PCPN TOTALS
OVER UPR MI...IS STILL UNCERTAIN. THE 00Z GFS INDICATES A FARTHER W
TRACK ACROSS THE ERN U.P. THAN THE 00Z ECMWF/UKMET RUNS...BUT THE
GFS INDICATES THE PCPN WOULD BE HEAVY SN OVER THE W HALF OF UPR MI.
THE FARTHER E ECMWF MODEL GENERATES MUCH LIGHT PCPN OVER THE E.
CONSIDERING THE SGNFT DIFFERNCES THAT REMAIN...RELIED ON THE MODEL
CONSENSUS FOR THE FCST DETAILS. THIS CONSENSUS SUPPORTS HIER POPS
OVER THE E WITH A CHANGE IN PTYPE FM MIXED RA/SN TO MAINLY SN AS THE
INCREASING N BACKING NW WINDS ADVECT COLDER AIR INTO THE CWA.
IN THE WAKE OF THE DEEPENING LO MOVING INTO ONTARIO ON XMAS DAY...
THE PRES GRADIENT IS PROGGED TO TIGTHEN SGNFTLY AND H925 WINDS
INCREASE TO NEAR 45 KTS. NW WIND GUSTS MAY AT LEAST APRCH ADVY
CRITERIA...ESPECIALLY AT EXPOSED LOCATIONS NEAR LK SUP.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 652 AM EST SAT DEC 20 2014
LOW CLOUD FCST THE MAIN ISSUE THROUGH TONIGHT. CURRENTLY MVFR CIGS
REMAIN OVER KIWD AND ARE JUST TO WEST OF KCMX. EXPECT BKN-OVC CIGS
TO PERSIST AT BOTH TAFS TODAY AND TONIGHT. PRIMARY ISSUE WILL BE
WHETHER CIGS STAY BLO 020 OR JUST ABOVE AS THIS AFFECTS ALTERNATE
FLIGHT PLANNING. MEANWHILE...AT KSAW...STILL SOME FOG ISSUES VERY
EARLY ON AS LOW CLOUDS ARE JUST TO THE WEST AND MID CLOUDS HAVE
THINNED SOME IN THE LAST COUPLE HOURS. FOG IS SHALLOW THOUGH AND NOT
WIDESPREAD...SO DO NOT IT EXPECT IT TO LAST TOO LONG. THIS WILL BE
ESPECIALLY TRUE AFTER BKN-OVC MVFR STRATUS DECK SPREADS OVER CNTRL
UPR MICHIGAN THIS MORNING. WILL COVER THE FOG WITH TEMPO WHICH WORKED
WELL EARLIER TONIGHT AT KSAW. MVFR CLOUDS SHOULD PERSIST INTO TONIGHT
THOUGH LIKE THE WESTERN TAF SITES...MAIN QUESTION WILL REVOLVE
AROUND WHETHER PREVAILING CIGS END UP ABOVE OR BELOW 020.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 434 AM EST SAT DEC 20 2014
EXPECT S WINDS UNDER 20 KTS ASSOCIATED WITH HI PRES DRIFTING E THRU
SE CANADA TO PERSIST INTO SUN. THE S WINDS WILL INCREASE UP TO 25
KTS OVER AT LEAST THE E HALF OF THE LAKE ON SUN INTO MON AS A LO
PRES TRACKS E THRU THE NORTHERN PLAINS AND THE PRES GRADIENT
TIGHTENS OVER THE UPPER LAKES. AS ANOTHER LO PRES DEVELOPS TO THE S
ON TUE...THE FLOW WILL TEND TO BACK TOWARD THE NW. THE LATEST TRENDS
INDICATE THIS LO WILL DEEPEN SIGNFICANTLY AS IT MOVES TO THE NNE
THRU THE CENTRAL GREAT LAKES ON WED AND INTO SE ONTARIO ON XMAS DAY.
THE POTENTIAL FOR A N VEERING NW GALE EVENT FROM LATE ON WED THRU
XMAS DAY NOW LOOKS GREATER.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLA
LONG TERM...KC
AVIATION...JLA
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
435 AM EST SAT DEC 20 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 434 AM EST SAT DEC 20 2014
WV LOOP AND 00Z RAOBS SHOW A LARGE SCALE ZONAL FLOW...BUT THERE IS
EMBEDDED AMPLIFICATION. TROUGHING WAS AS CLOSE BY AS NORTHERN PLAINS
AND MINNESOTA THIS MORNING. PRIMARY PV ANAMOLIES/SHORTWAVES WITHIN
TROUGH WERE OVER FAR NORTHWEST ONTARIO AND OVER WESTERN IOWA. WEAK
SFC TROUGH NOTED OVER WESTERN MINNESOTA TOO...WHILE SFC RIDGING
EXTENDING OUT OF QUEBEC WAS STILL MAIN FEATURE OVER GREAT LAKES. THE
ONTARIO WAVE AND WEAK WARM AIR ADVECTION AHEAD OF THE MINNESOTA
TROUGH AND UPSLOPE LOW-LEVEL FLOW IS SUPPORTING LGT WINTRY MIX OF
SNOW AND FREEZING DRIZZLE OVER NORTHERN MINNESOTA THIS MORNING. ONLY
AFFECT FM ONTARIO SHORTWAVE OVER UPR MICHIGAN IS BATCH OF MID CLOUDS
OVER WEST HALF OF CWA. NO PRECIP THROUGH. ONLY WEATHER OF NOTE IN
THE CWA THIS MORNING IS PATCHY DENSE FOG OVER CNTRL CWA...VCNTY OF
IMT TO SAW.
ONTARIO WAVE MOVES LITTLE EASTWARD TODAY AS ANOTHER SHORTWAVE
CURRENTLY OVER MT TRIES TO CATCH UP WITH IT. THUS...SFC TROUGH AND
WARM AIR ADVECTION STAY MAINLY OVER MN. RAP SHOWS WEAK LIFT TRYING
TO IMPACT KEWEENAW THIS MORNING INTO EARLY AFTN...BUT IT LOOKS MUCH
DRIER THAN IT IS UPSTREAM OVER MN WHERE PRECIP IN OCCURRING THIS
MORNING...SO NOT EXPECTING ANY PRECIP OUT OF THIS FOR OUR AREA. LOW
CLOUDS OVER NW WI AND WEST UPR MICHIGAN GRADUALLY EASE
EASTWARD...BUT A FEW SPOTS IN EAST HALF OF CWA MAY STAY CLEAR OF THE
LOW CLOUDS ALL DAY. TOUGH TO SAY EXACTLY WHERE THOUGH AS THERE ARE
DIFFERENT AREAS OF CLOUDS AFFECTING THE AREA AND MODELS FORECASTING
OF THEM IS ONLY FAIR. FOR TEMPS...WENT AT OR 1-2 DEGREES ABOVE
FRIDAY READINGS AS 925MB TEMPS WARM SLIGHTLY COMPARED TO FRIDAY.
WHERE SUNSHINE CAN PERSIST INTO THE AFTN...TEMPS COULD BUMP INTO THE
MID 30S. BEST SHOT AT THAT WOULD BE EAST CENTRAL CWA...VCTY OF
MUNISING AND GRAND MARAIS. FARTHER WEST...CLOUDS WILL HOLD TEMPS
DOWN OVER INTERIOR WEST TO UPR 20S. INTO THIS EVENING...EXPECT LOW
CLOUDS /HIGHER 925MB-850MB RH/ TO BE OVER WEST HALF OF CWA AND ALSO
THE FAR EAST CWA. EVENTUALLY THOUGH...CLOUDS SHOULD FILL IN OVER ALL
CWA. UNTIL THAT OCCURS...TEMPS FOR INTERIOR CNTRL CWA OR AT LEAST
PORTIONS OF THESE AREAS MAY DROP OFF QUICKLY. CLOSEST MODEL TO
INCICATE THAT WAS BIAS CORRECTED NAM MOS. TWEAKED DOWN EVEN FURTHER
THOUGH /LOW TEENS/ SEEING HOW MUCH TEMPS FELL EARLY THIS MORNING
WHERE SKIES WERE CLEAR. ALSO WILL ADD FOG TO THOSE AREAS SINCE THESE
TEMPS WILL BE WELL BELOW THE EXPECTED AFTN DWPNTS. WHERE CLOUDS STAY
IN ALL NIGHT...MIN TEMPS LIKELY STAY ABOVE 20 DEGREES.
SOUNDINGS FM NAM AND GFS INDICATE INCREASING SUB 950MB MOISTURE
LATE TONIGHT FM THE SOUTH AND WITH UPSLOPE SOUTH FLOW OVER CNTRL
CWA COULD SEE PATCHY FREEZING DRIZZLE IMT TO NEGAUNEE. NOT MUCH UVM
SHOWN ON THE SOUNDINGS THOUGH...SO LEFT IT OUT OF GRIDS ATTM.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 434 AM EST SAT DEC 20 2014
MAIN FOCUS FOR THE LONGER TERM REMAINS THE POTENTIAL FOR SOME SN OR
MIXED PCPN IN THE MON INTO XMAS PERIOD ASSOCIATED WITH A DEEPENING
UPR TROF IN THE CENTRAL CONUS AS A SERIES OF SHRTWVS RIDING OVER A
MEAN RDG ALONG THE W COAST DIG INTO THE PLAINS. THE STRONGEST OF
THESE DISTURBANCE IS NOW OVER THE NE PACIFIC OCEAN. ALTHOUGH THE
MODELS ARE COMING INTO BETTER AGREEMENT ON WARMER LLVL TEMPS IN THE
TUE/WED TIME AND ON THE DEVELOPMENT OF A LO PRES IN THE LO/MID MS
RIVER VALLEY THAT WL TRACK SOMEWHERE NEAR THE CENTRAL GREAT LKS ON
WED AND INTO CANADA ON XMAS DAY...THERE ARE STILL SOME SIGNIFICANT
DIFFERENCES ON THE DETAILS OF HOW THE INTERACTION/PHASING BTWN THESE
SEPARATE DISTURBANCES THAT ARE STILL OVER THE DATA POOR PACIFIC WL
IMPACT THE SFC LO TRACK AND UPR MI.
SUN/SUN NIGHT...AS LLVL S WIND BTWN DEPARTING HI PRES IN SE CANADA
AND FALLING MSLP TO THE W ADVECT MOISTER LLVL AIR INTO THE CWA...
OPTED TO INCLUCE SOME FREEZING DZ OVER THE SCENTRAL IN THE MRNG
WHERE LLVL WIND WL UPSLOPE OFF LK MI. THEN OPERATIONAL MODELS SHOW A
SHRTWV MOVING E FM THE NRN PLAINS ACROSS THE NW GREAT LKS AND INTO
NW ONTARIO BY 12Z MON... BRINGING A PERIOD OF DEEP LYR QVECTOR CNVGC
ASSOCIATED WITH SOME DPVA AND ISENTROPIC ASCENT BEST DEPICTED ON THE
285-290K SFCS /ABOUT H85-75/ IN THE STRONGER SSW FLOW BTWN HI PRES
OVER THE CNDN MARITIMES AND LO PRES IN THE NRN PLAINS. ARRIVAL OF
THE DEEPER MSTR SHOULD END THE FREEZING DZ. THE BULK OF THE GUIDANCE
INDICATES THE ACCOMPANYING SN WL BEGIN OVER THE SCENTRAL SUN AFTN
AND THEN OVERSPREAD THE REST OF THE FA THRU SUN NGT. THE NAM SHOWS
THE HIEST QPF UP TO 0.25-0.30 INCH OVER THE SCENTRAL...WHERE THE
NEAR SFC SSE FLOW WL UPSLOPE OFF LK MI AND H85 MSTR CNVGC IS A BIT
SHARPER. THE GFS ON THE OTHER HAND SHIFTS THE HIER QPF TO OVER THE
NW CWA LATE AT NGT. GIVEN THE GREATER CONSISTENCY OF THE NAM WITH
PREVIOUS FCST GUIDANCE...TENDED TOWARD THAT MODEL SCENARIO. WL BUMP
POPS UP TO LIKELY OVER THE SCENTRAL CENTERED ARND SUN EVNG WHEN THE
FORCING WL BE GREATEST. THERE COULD BE A FEW INCHES OF SN ACCUM IN
THIS AREA AS WELL. SSW FLOW UP THE LENGTH OF LK MI MAY SUPPORT SOME
HIER POPS OVER THE E...BUT MARGINAL CHILL OF THE AIRMASS FOR LK
ENHANCEMENT WITH H85 TEMPS RISING TO -5C BY 00Z MON SHOULD LIMIT THE
POTENTIAL FOR A SGNFT IMPACT. TEMPS WL REMAIN ABOVE NORMAL...
ESPECIALLY ON SUN NGT WITH CLD COVER AND A STEADY S WIND GREATLY
LIMITING THE DIURNAL TEMP FALL.
MON...FOLLOWING THE EXIT OF THE SHRTWV INTO NW ONTARIO ON MON AND
THE ARRIVAL OF SOME MID LVL DRYING ASSOCIATED WITH A SHRTWV RDG AXIS
ROTATING NEWD THRU THE NW GREAT LKS TO THE E OF THE DEEPENING UPR
TROF IN THE PLAINS...EXPECT DIMINISHED POPS. BUT PERSISTENT WAA IN
THE DEEP S FLOW BTWN LO PRES SLIDING SEWD THRU THE NRN PLAINS AND HI
PRES OVER THE CNDN MARITIMES WL CAUSE LOTS OF CLDS AND CONTINUED LO
CHC POPS. AS THE LLVLS WARM INTO THE 30S ESPECIALLY NEAR THE WARMING
INFLUENCE OF THE GREAT LKS...LIGHT PCPN MAY INCLUDE A MIX OF RA AND
SN.
MON NGT/TUE...THE 00Z GFS REMAINS CONSISTENT ON SHOWING A CLOSED H5
LO WITHIN THE DEEPENING CENTRAL CONUS TROF/DEEPER SFC LO PRES MOVING
INTO THE UPR LKS DURING THIS TIME ALONG WITH HIER H85 TEMPS UP TO
ARND 0C. THE 12Z/00Z ECMWF MODELS ON THE OTHER HAND HOLD THE CLOSED
H5 LO/SFC LO FARTHER TO THE SW...WITH A SLOWER ARRIVAL OF DEEPER
MSTR AND LOWER H85 TEMPS. BOTH MODELS SHOW DISTURBANCES DIGGING SEWD
TO THE E OF THE UPR RDG ACROSS THE W DEEPENING THE PLAINS TROF.
SINCE THIS GREATER FORCING INTO THE SRN PLAINS SHOULD TEND TO HOLD
THE CLOSED LO THE SW...WL TEND TOWARD THE 12Z ECMWF SCENARIO. THIS
MODEL SHOWS DEEPER MSTR ARRIVING LATE MON NGT AND PERSISTING THRU
TUE AS THE WEAKER SHRTWV LIFTS NEWD AWAY FM CLOSED LO TO THE SW.
ALTHOUGH THE 00Z ECMWF H85 TEMPS ARE LOWER THAN FCST BY THE GFS...
THE FCST H100-85 THKNS IS ONLY A BIT LOWER THAN THE GFS FCST. A LOOK
AT THE 00Z ECMWF FCST SDNGS SHOW A TREND TOWARD A WARMER NEAR SFC
LYR THAT WOULD SUPPORT MORE RA...AS SHOWN BY RECENT GFS RUNS. SO
TENDED TO RAISE FCST TEMPS AND INCLUDE A GREATER AREA OF AT LEAST A
MIX WITH RA. THE FCST SDNGS FM NEITHER MODEL SHOW AN ELEVATED WARM
LYR...SO THE PCPN SHOULD BE RA OR SN. ADDED A MENTION OF SOME FOG
DURING THE MON NIGHT/TUE TIME TO REFLECT THE RA/HIER TEMPS AND
DEWPTS OVER A MELTING SN PACK AT MANY LOCATIONS THAT UPSLOPE OFF LK
MI IN THE EXPECTED LLVL SE FLOW. THIS MIXED PCPN WL TEND TO DIMINISH
ON TUE NGT AS SOME UPR DRYING FOLLOWS THE SHRTWV EXITING NNEWD INTO
ONTARIO.
WED/THU...THE LONGER RANGE MODELS ARE BEGINNING TO COME INTO BETTER
AGREEMENT ON SHOWING A SECOND LO DVLPG IN THE LOWER TO MID MS RIVER
VALLEY ON TUE AT THE SRN END OF THE DEEPING CENTRAL CONUS TROF AND
THEN MOVING NNE INTO THE CENTRAL GREAT LKS ON WED AND THEN INTO ERN
ONTARIO ON XMAS DAY WHILE DEEPENING SIGNIFICANTLY AS THE UPR TROF
TAKES ON A MORE NEGATIVE TILT. NOT SURPRISINGLY...THE EXACT TRACK OF
THE SFC LO...WHICH WL MAKE A SGNFT DIFFERNCE ON PTYPE/PCPN TOTALS
OVER UPR MI...IS STILL UNCERTAIN. THE 00Z GFS INDICATES A FARTHER W
TRACK ACROSS THE ERN U.P. THAN THE 00Z ECMWF/UKMET RUNS...BUT THE
GFS INDICATES THE PCPN WOULD BE HEAVY SN OVER THE W HALF OF UPR MI.
THE FARTHER E ECMWF MODEL GENERATES MUCH LIGHT PCPN OVER THE E.
CONSIDERING THE SGNFT DIFFERNCES THAT REMAIN...RELIED ON THE MODEL
CONSENSUS FOR THE FCST DETAILS. THIS CONSENSUS SUPPORTS HIER POPS
OVER THE E WITH A CHANGE IN PTYPE FM MIXED RA/SN TO MAINLY SN AS THE
INCREASING N BACKING NW WINDS ADVECT COLDER AIR INTO THE CWA.
IN THE WAKE OF THE DEEPENING LO MOVING INTO ONTARIO ON XMAS DAY...
THE PRES GRADIENT IS PROGGED TO TIGTHEN SGNFTLY AND H925 WINDS
INCREASE TO NEAR 45 KTS. NW WIND GUSTS MAY AT LEAST APRCH ADVY
CRITERIA...ESPECIALLY AT EXPOSED LOCATIONS NEAR LK SUP.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1239 AM EST SAT DEC 20 2014
LOW CLOUD FCST MAY BE TRICKY TONIGHT AT KSAW AS LATEST SATELLITE
IMAGERY REVEALS AN AREA OF CLEARING OVER CNTRL UPPER MI. ALSO SEEING
FOG DEVELOP IN LAST HR THERE AS WELL...SO AS LONG AS SKIES STAY
CLEAR...WILL HAVE FOG ISSUES. DUE TO THE BKN MID CLOUDS LURKING
JUST TO THE WEST OF KSAW AND INCREASING HIGH CLOUDS...HAVE FEELING
THAT FOG WILL BE IN AND OUT AND NOT A PREVAILING CONDITION SO JUST
INCLUDED IN TEMPO. MODEL GUIDANCE SUGGESTS THAT KSAW COULD STAY CLR
OF BKN-OVC LOW CLOUDS THROUGH THE MORNING HRS BEFORE CLOUDING BACK
UP AGAIN WITH AN MVFR DECK BY THIS AFTN.
FOR THE WESTERN TAF SITES...EXPECT LOW CLOUDS TO PERSIST THROUGH
MUCH OF PD AS WARM AIR AND MOISTURE ADVECTION CONTINUES TO ADVECT
OVER AREA BETWEEN A HIGH PRESSURE SYSTEM TO THE EAST AND A TROUGH
OVER THE NORTHERN PLAINS. ONLY EXCEPTION WILL BE EARLY ON AT KCMX
WHERE ONLY MID CLOUDS ARE NOTED TO START THIS TAF PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 434 AM EST SAT DEC 20 2014
EXPECT S WINDS UNDER 20 KTS ASSOCIATED WITH HI PRES DRIFTING E THRU
SE CANADA TO PERSIST INTO SUN. THE S WINDS WILL INCREASE UP TO 25
KTS OVER AT LEAST THE E HALF OF THE LAKE ON SUN INTO MON AS A LO
PRES TRACKS E THRU THE NORTHERN PLAINS AND THE PRES GRADIENT
TIGHTENS OVER THE UPPER LAKES. AS ANOTHER LO PRES DEVELOPS TO THE S
ON TUE...THE FLOW WILL TEND TO BACK TOWARD THE NW. THE LATEST TRENDS
INDICATE THIS LO WILL DEEPEN SIGNFICANTLY AS IT MOVES TO THE NNE
THRU THE CENTRAL GREAT LAKES ON WED AND INTO SE ONTARIO ON XMAS DAY.
THE POTENTIAL FOR A N VEERING NW GALE EVENT FROM LATE ON WED THRU
XMAS DAY NOW LOOKS GREATER.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLA
LONG TERM...KC
AVIATION...JLA
MARINE...KC
AREA FORECAST DISCUSSION
NWS DULUTH MN
817 PM CST SUN DEC 21 2014
.UPDATE...
ISSUED AT 817 PM CST SUN DEC 21 2014
WE ISSUED A WINTER WEATHER ADVISORY FOR TONIGHT INTO MONDAY
MORNING FOR THE IRON RANGE AND ARROWHEAD FOR A COMBINATION OF
FREEZING DRIZZLE AND LIGHT SNOW. AN AREA OF FREEZING DRIZZLE WAS
LIFTING NORTH THROUGH THOSE AREAS AND TEMPERATURES ARE A BIT
COOLER. BUFR SOUNDINGS SHOW MOISTENING AROUND OR SHORTLY AFTER
MIDNIGHT WHICH SHOULD CAUSE THE FREEZING DRIZZLE MIX WITH OR
CHANGE OVER TO SNOW.
UPDATE ISSUED AT 556 PM CST SUN DEC 21 2014
WAA AND A SHORTWAVE HAVE PRODUCED WIDESPREAD SNOW OVER MUCH OF
NORTHWEST WISCONSIN TODAY INTO EARLY THIS EVENING WITH SEVERAL
REPORTS OF 2 TO 3 INCHES SO FAR. RADAR SHOWS THIS SNOW WAS SLOWLY
DIMINISHING FROM WEST TO EAST AND THE VSBY AT KHYR HAS RISEN FROM
A HALF MILE TO 4 MILES. SATELLITE IMAGERY AND FORECAST SOUNDINGS
SHOW DRIZZLE/FREEZING DRIZZLE WILL BE POSSIBLE FURTHER WEST AND WE
HAVE HAD SEVERAL REPORTS OF THAT AS WELL. WE WILL UPDATE GRIDS TO
ACCOUNT FOR THE LATEST TRENDS/PRECIP TYPES.
STRONGER ECHOES WERE ALSO OCCURRING OVER PORTIONS OF SOUTHERN
MINNESOTA. THE HRRR BRINGS THIS AREA NORTH THROUGH THE NIGHT IN
LINE WITH THE OPERATIONAL RUNS. PRECIP TYPE LATER TONIGHT WILL
CONTINUE TO BE A CHALLENGE AND WE WILL MENTION OF MIX OF
SNOW/DRIZZLE OR FREEZING DRIZZLE DEPENDING ON SURFACE TEMPS. BUFR
SOUNDINGS AT KDLH SHOW SNOW BECOMING MORE LIKELY AROUND MIDNIGHT
AS THE COLUMN MOISTENS...WITH KINL LOOKING MORE LIKE
DRIZZLE/FREEZING DRIZZLE THROUGH THE NIGHT AS THE MOISTENING TAKES
LONGER TO REACH THAT AREA. WE WILL ALSO SEE LOW LEVEL TEMPS WARM
LATE TONIGHT INTO MONDAY MORNING WHICH COULD AGAIN CAUSE A MIX TO
OCCUR.
FOG WILL CONTINUE OVERNIGHT WITH LOWEST VSBYS AROUND LAKE
SUPERIOR. WE MAY NEED A DENSE FOG ADVISORY FOR THE NORTH SHORE
DOWN INTO THE TWIN PORTS AREA...BUT WILL WAIT A BIT LONGER BEFORE
ISSUING ONE AS VSBYS HAVE AT LEAST FOR THE TIME BEING COME UP SOME.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY AFTERNOON)
ISSUED AT 329 PM CST SUN DEC 21 2014
MAIN CONCERNS IN THE SHORT TERM REMAIN FOCUSED AROUND THE
INCOMING...LONG DURATION WINTER STORM EXPECTED TO IMPACT THE
NORTHLAND EARLY THIS WEEK WITH A WINTRY MIX OF SNOW...RAIN...SLEET
AND FREEZING DRIZZLE POSSIBLE.
A WINTER STORMS WATCH REMAINS IN EFFECT FOR THE ARROWHEAD INCLUDING
LAKE AND COOK COUNTIES...BUT THE TIME HAS BEEN ADJUSTED TO START
MONDAY NIGHT AND END WEDNESDAY MORNING. THE MAIN CONCERNS WITHIN THE
WATCH AREA WILL BE THE POTENTIAL FOR HEAVY SNOW ACCUMULATIONS.
AN INITIAL LEAD S/W IS ROTATING NEWD THROUGH THE UPPER MIDWEST AND
WRN ONTARIO THIS AFTERNOON AND WILL MOVE SLOWLY EWD TONIGHT AS WEAK
RIDGING ALOFT AND AN ASSOCIATED DRY SLOT PUSH IN FROM THE SOUTH
BEHIND THE WAVE AND AHEAD OF THE MAIN LOW PRESSURE SYSTEM SWINGING
THROUGH THE MIDWEST MON NIGHT THROUGH WEDNESDAY.
WILL SEE SNOW SHOWERS PERSIST THROUGH THIS EVENING WITH LIGHT
ACCUMULATIONS LIKELY. THE HEAVIEST SNOW AMTS TONIGHT WILL BE ACROSS
THE ARROWHEAD AND INTO PORTIONS OF NW WI WHERE AN ADDITIONAL 1 TO 2
INCHES IS POSSIBLE. AS THE UPPER WAVE SLIDES NEWD AND THE RIDGE
BUILDS IN...THE DRY AIR ALOFT WILL ALLOW THE COLUMN TO LOSE ICE
CRYSTALS AND CHANGE THE PRECIP FROM LIGHT SNOW OVER TO A LIGHT
FREEZING DRIZZLE. TEMPERATURES WILL ALSO WARM GRADUALLY THROUGH THE
NIGHT FROM THE LOWER 30S EARLY THIS EVENING TO THE MID 30S BY MON
MORNING. TEMPERATURES ALOFT WILL WARM AS WELL WITH A NOSE OF 0 TO +1
DEG C AIR LIFTS NWD INTO THE AREA AND ALLOWS THE PRECIP TO CHANGE
OVER TO A MIX OF RAIN/SNOW AND/OR SLEET DURING THE DAY MONDAY. WILL
LIKELY SEE WIDESPREAD SNOWFALL AMTS ON MONDAY RANGE FROM A HALF TO
ONE INCH...WITH CLOSER TO 2 TO 3 INCHES POSSIBLE OVER THE ARROWHEAD.
BETTER CHANCES FOR ACCUMULATING SNOW EXIST MON NIGHT THROUGH TUE
NIGHT.
PATCHY FOG WILL ALSO PERSIST TONIGHT AND INTO EARLY IN THE WEEK.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 329 PM CST SUN DEC 21 2014
EXTENDED RANGE FOCUS ON LONG WAVE TROUGH WITH CLOSED H50 THAT TRACKS
THROUGH THE CENTRAL PLAINS AND LIFTS INTO THE GREAT LAKES REGION
DURING THE TUESDAY/WEDNESDAY PERIODS.
ALTHOUGH MODELS ARE COMING INTO BETTER ALIGNMENT...THERE CONTINUES
TO BE RUN TO RUN DIFFERENCES IN TRACK OF THE LOW...WHICH WILL BE THE
DETERMINING FACTOR FOR PLACEMENT OF THE BEST FORCING AND HIGHEST
SNOWFALL AMOUNTS. AT THIS TIME...THE SFC LOW IS FCST TO TRACK OVER
WISCONSIN MONDAY NIGHT/TUESDAY...WHICH WILL PRODUCE GUST NORTHEAST
WINDS OVER LAKE SUPERIOR WHILE ROTATING A BAND OF SNOW LOCATED IN A
DEFORMATION ZONE ON THE ON THE NW FLANK OF THE LOW ACROSS MUCH OF
THE NORTHLAND. LATEST GUIDANCE IS SUGGESTING THAT A CORRIDOR OF QPF
AMOUNTS IN EXCESS OF A HALF INCH WILL BE FOUND DURING THIS TIME DUE
TO THE ABUNDANCE OF MOISTURE AND HIGH PWAT VALUES. ALTHOUGH DETAILS
HAVE YET TO BE REFINED AND SFC TEMPS MAY WARRANT SOME INITIAL MIXING
OF SNOW/RAIN/DRIZZLE...SNOWFALL TOTALS FOR THE MONDAY NIGHT THROUGH
WEDNESDAY MORNING TIME FRAME OF GENERALLY 4 TO 8 INCHES ARE EXPECTED
OVER THE NORTHLAND. THE GREATEST UNCERTAINTY IS IN THE WESTERN HALF
ZONES /NORTH CENTRAL MN/ WHERE A WEDGE OF DRY AIR WILL WRAP AROUND
THE LOW AND LIMIT SNOWFALL TOTALS.
DUE TO THE LONG DURATION OF THE SNOW...ANTICIPATING THAT A WINTER
WEATHER ADVISORY WILL BE NEEDED FOR MUCH OF THE FORECAST AREA DURING
THE MONDAY NIGHT INTO EARLY WEDNESDAY PERIODS.
LONG RANGE MODELS SHOW THE ACTIVE PATTERN THROUGH THE REMAINDER OF
THE EXTENDED FCST...WITH A PERSISTENT CYCLONIC FLOW AND EMBEDDED
SHORT WAVES.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 556 PM CST SUN DEC 21 2014
MAINLY IFR/LIFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD IN
FOG ALONG WITH PERIODS OF SNOW...DRIZZLE OR FREEZING DRIZZLE.
BRIEF AND WEAK MID LEVEL RIDGING MONDAY AFTERNOON SHOULD LEAD TO A
LULL IN PRECIP COVERAGE FOR A TIME MONDAY AFTERNOON...ESPECIALLY
OVER EASTERN AREAS BEFORE IT RAMPS UP AGAIN MONDAY NIGHT.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 33 35 33 36 / 70 90 80 80
INL 31 35 32 33 / 50 80 70 70
BRD 32 35 31 34 / 70 90 80 80
HYR 34 35 33 35 / 60 80 80 80
ASX 33 37 33 36 / 70 70 80 80
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL 10 AM CST MONDAY FOR MNZ011-012-
019>021.
WINTER STORM WATCH FROM LATE MONDAY NIGHT THROUGH LATE TUESDAY
NIGHT FOR MNZ012-020-021.
WI...NONE.
LS...NONE.
&&
$$
UPDATE...MELDE
SHORT TERM...BJT
LONG TERM...GRANING
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS DULUTH MN
557 PM CST SUN DEC 21 2014
.UPDATE...
ISSUED AT 556 PM CST SUN DEC 21 2014
WAA AND A SHORTWAVE HAVE PRODUCED WIDESPREAD SNOW OVER MUCH OF
NORTHWEST WISCONSIN TODAY INTO EARLY THIS EVENING WITH SEVERAL
REPORTS OF 2 TO 3 INCHES SO FAR. RADAR SHOWS THIS SNOW WAS SLOWLY
DIMINISHING FROM WEST TO EAST AND THE VSBY AT KHYR HAS RISEN FROM
A HALF MILE TO 4 MILES. SATELLITE IMAGERY AND FORECAST SOUNDINGS
SHOW DRIZZLE/FREEZING DRIZZLE WILL BE POSSIBLE FURTHER WEST AND WE
HAVE HAD SEVERAL REPORTS OF THAT AS WELL. WE WILL UPDATE GRIDS TO
ACCOUNT FOR THE LATEST TRENDS/PRECIP TYPES.
STRONGER ECHOES WERE ALSO OCCURRING OVER PORTIONS OF SOUTHERN
MINNESOTA. THE HRRR BRINGS THIS AREA NORTH THROUGH THE NIGHT IN
LINE WITH THE OPERATIONAL RUNS. PRECIP TYPE LATER TONIGHT WILL
CONTINUE TO BE A CHALLENGE AND WE WILL MENTION OF MIX OF
SNOW/DRIZZLE OR FREEZING DRIZZLE DEPENDING ON SURFACE TEMPS. BUFR
SOUNDINGS AT KDLH SHOW SNOW BECOMING MORE LIKELY AROUND MIDNIGHT
AS THE COLUMN MOISTENS...WITH KINL LOOKING MORE LIKE
DRIZZLE/FREEZING DRIZZLE THROUGH THE NIGHT AS THE MOISTENING TAKES
LONGER TO REACH THAT AREA. WE WILL ALSO SEE LOW LEVEL TEMPS WARM
LATE TONIGHT INTO MONDAY MORNING WHICH COULD AGAIN CAUSE A MIX TO
OCCUR.
FOG WILL CONTINUE OVERNIGHT WITH LOWEST VSBYS AROUND LAKE
SUPERIOR. WE MAY NEED A DENSE FOG ADVISORY FOR THE NORTH SHORE
DOWN INTO THE TWIN PORTS AREA...BUT WILL WAIT A BIT LONGER BEFORE
ISSUING ONE AS VSBYS HAVE AT LEAST FOR THE TIME BEING COME UP SOME.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY AFTERNOON)
ISSUED AT 329 PM CST SUN DEC 21 2014
MAIN CONCERNS IN THE SHORT TERM REMAIN FOCUSED AROUND THE
INCOMING...LONG DURATION WINTER STORM EXPECTED TO IMPACT THE
NORTHLAND EARLY THIS WEEK WITH A WINTRY MIX OF SNOW...RAIN...SLEET
AND FREEZING DRIZZLE POSSIBLE.
A WINTER STORMS WATCH REMAINS IN EFFECT FOR THE ARROWHEAD INCLUDING
LAKE AND COOK COUNTIES...BUT THE TIME HAS BEEN ADJUSTED TO START
MONDAY NIGHT AND END WEDNESDAY MORNING. THE MAIN CONCERNS WITHIN THE
WATCH AREA WILL BE THE POTENTIAL FOR HEAVY SNOW ACCUMULATIONS.
AN INITIAL LEAD S/W IS ROTATING NEWD THROUGH THE UPPER MIDWEST AND
WRN ONTARIO THIS AFTERNOON AND WILL MOVE SLOWLY EWD TONIGHT AS WEAK
RIDGING ALOFT AND AN ASSOCIATED DRY SLOT PUSH IN FROM THE SOUTH
BEHIND THE WAVE AND AHEAD OF THE MAIN LOW PRESSURE SYSTEM SWINGING
THROUGH THE MIDWEST MON NIGHT THROUGH WEDNESDAY.
WILL SEE SNOW SHOWERS PERSIST THROUGH THIS EVENING WITH LIGHT
ACCUMULATIONS LIKELY. THE HEAVIEST SNOW AMTS TONIGHT WILL BE ACROSS
THE ARROWHEAD AND INTO PORTIONS OF NW WI WHERE AN ADDITIONAL 1 TO 2
INCHES IS POSSIBLE. AS THE UPPER WAVE SLIDES NEWD AND THE RIDGE
BUILDS IN...THE DRY AIR ALOFT WILL ALLOW THE COLUMN TO LOSE ICE
CRYSTALS AND CHANGE THE PRECIP FROM LIGHT SNOW OVER TO A LIGHT
FREEZING DRIZZLE. TEMPERATURES WILL ALSO WARM GRADUALLY THROUGH THE
NIGHT FROM THE LOWER 30S EARLY THIS EVENING TO THE MID 30S BY MON
MORNING. TEMPERATURES ALOFT WILL WARM AS WELL WITH A NOSE OF 0 TO +1
DEG C AIR LIFTS NWD INTO THE AREA AND ALLOWS THE PRECIP TO CHANGE
OVER TO A MIX OF RAIN/SNOW AND/OR SLEET DURING THE DAY MONDAY. WILL
LIKELY SEE WIDESPREAD SNOWFALL AMTS ON MONDAY RANGE FROM A HALF TO
ONE INCH...WITH CLOSER TO 2 TO 3 INCHES POSSIBLE OVER THE ARROWHEAD.
BETTER CHANCES FOR ACCUMULATING SNOW EXIST MON NIGHT THROUGH TUE
NIGHT.
PATCHY FOG WILL ALSO PERSIST TONIGHT AND INTO EARLY IN THE WEEK.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 329 PM CST SUN DEC 21 2014
EXTENDED RANGE FOCUS ON LONG WAVE TROUGH WITH CLOSED H50 THAT TRACKS
THROUGH THE CENTRAL PLAINS AND LIFTS INTO THE GREAT LAKES REGION
DURING THE TUESDAY/WEDNESDAY PERIODS.
ALTHOUGH MODELS ARE COMING INTO BETTER ALIGNMENT...THERE CONTINUES
TO BE RUN TO RUN DIFFERENCES IN TRACK OF THE LOW...WHICH WILL BE THE
DETERMINING FACTOR FOR PLACEMENT OF THE BEST FORCING AND HIGHEST
SNOWFALL AMOUNTS. AT THIS TIME...THE SFC LOW IS FCST TO TRACK OVER
WISCONSIN MONDAY NIGHT/TUESDAY...WHICH WILL PRODUCE GUST NORTHEAST
WINDS OVER LAKE SUPERIOR WHILE ROTATING A BAND OF SNOW LOCATED IN A
DEFORMATION ZONE ON THE ON THE NW FLANK OF THE LOW ACROSS MUCH OF
THE NORTHLAND. LATEST GUIDANCE IS SUGGESTING THAT A CORRIDOR OF QPF
AMOUNTS IN EXCESS OF A HALF INCH WILL BE FOUND DURING THIS TIME DUE
TO THE ABUNDANCE OF MOISTURE AND HIGH PWAT VALUES. ALTHOUGH DETAILS
HAVE YET TO BE REFINED AND SFC TEMPS MAY WARRANT SOME INITIAL MIXING
OF SNOW/RAIN/DRIZZLE...SNOWFALL TOTALS FOR THE MONDAY NIGHT THROUGH
WEDNESDAY MORNING TIME FRAME OF GENERALLY 4 TO 8 INCHES ARE EXPECTED
OVER THE NORTHLAND. THE GREATEST UNCERTAINTY IS IN THE WESTERN HALF
ZONES /NORTH CENTRAL MN/ WHERE A WEDGE OF DRY AIR WILL WRAP AROUND
THE LOW AND LIMIT SNOWFALL TOTALS.
DUE TO THE LONG DURATION OF THE SNOW...ANTICIPATING THAT A WINTER
WEATHER ADVISORY WILL BE NEEDED FOR MUCH OF THE FORECAST AREA DURING
THE MONDAY NIGHT INTO EARLY WEDNESDAY PERIODS.
LONG RANGE MODELS SHOW THE ACTIVE PATTERN THROUGH THE REMAINDER OF
THE EXTENDED FCST...WITH A PERSISTENT CYCLONIC FLOW AND EMBEDDED
SHORT WAVES.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 556 PM CST SUN DEC 21 2014
MAINLY IFR/LIFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD IN
FOG ALONG WITH PERIODS OF SNOW...DRIZZLE OR FREEZING DRIZZLE.
BRIEF AND WEAK MID LEVEL RIDGING MONDAY AFTERNOON SHOULD LEAD TO A
LULL IN PRECIP COVERAGE FOR A TIME MONDAY AFTERNOON...ESPECIALLY
OVER EASTERN AREAS BEFORE IT RAMPS UP AGAIN MONDAY NIGHT.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 33 35 33 36 / 70 90 80 80
INL 31 35 32 33 / 50 80 70 70
BRD 32 35 31 34 / 70 90 80 80
HYR 34 35 33 35 / 60 80 80 80
ASX 35 37 33 36 / 60 70 80 80
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER STORM WATCH FROM LATE MONDAY NIGHT THROUGH LATE TUESDAY
NIGHT FOR MNZ012-020-021.
WI...NONE.
LS...NONE.
&&
$$
UPDATE...MELDE
SHORT TERM...BJT
LONG TERM...GRANING
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS BILLINGS MT
820 PM MST SUN DEC 21 2014
.UPDATE...
SEVERAL CHANGES TO INHERITED FORECAST THIS EVENING...MAINLY
CENTERED AROUND EXPIRING ASSORTED HIGHLIGHTS FOR WESTERN ZONES.
THE WINDS ACROSS WESTERN ROUTES HAVE TAPERED OFF SIGNIFICANTLY
SINCE SUNSET...AND SHOULD NOT THREATEN WARNING AND ADVISORY
CRITERIA AGAIN OVERNIGHT OR MONDAY. HAVE CANCELLED ALL WIND
HIGHLIGHTS AND PARED WINDS BACK OVERNIGHT. BREEZY CONDITIONS WILL
CONTINUE THROUGH TOMORROW IN MOST AREAS...BUT WILL BE BELOW
HIGHLIGHT CRITERIA.
ADDITIONALLY...CANCELLED THE WINTER STORM WARNING FOR THE
BEARTOOTH/ABSAROKA MOUNTAINS. ALTHOUGH SNOW WILL CONTINUE THROUGH
THE NIGHT AND MUCH OF TOMORROW...ACCUMULATIONS WILL BE
SIGNIFICANTLY LIGHTER.
OTHERWISE CURRENT FORECAST APPEARS TO BE IN GOOD SHAPE. AAG
&&
.SHORT TERM...VALID FOR MON AND TUE...
DYNAMIC SHORTWAVE IN NW FLOW ALOFT CURRENTLY PUSHING THROUGH
SOUTHEAST MT. STRONG WINDS HAVE BEEN OCCURRING FOR SEVERAL HOURS
IN HARLOWTON AND JUST RECENTLY WE HAVE SEEN GUSTS TO 58-59 MPH
SURFACE AT BILLINGS AND COLUMBUS...WITH SOME ASSISTANCE FROM THE
LIGHT SHOWER ACTIVITY AROUND THE AREA. PEAK GUSTS COINCIDE PRETTY
WELL WITH RAP 800MB WINDS...AND AS TEMPS HAVE REACHED THE LOW 50S
THE BOUNDARY LAYER IS WELL-MIXED. RAP/GFS SHOW 800MB FLOW
INCREASING TO 55 KTS OVER THE NEXT FEW HOURS FROM BILLINGS TO
SHERIDAN...IN PATH OF VORT MAX AS SEEN ON WATER VAPOR IMAGERY.
GIVEN THE INGREDIENTS AND AN EXPECTATION OF A FEW HOURS OF STRONG
W-NW WINDS HAVE ISSUED A HIGH WIND WARNING THRU MIDNIGHT TO
INCLUDE COLUMBUS...BILLINGS...HARDIN...LODGE GRASS AND SHERIDAN.
ELSEWHERE WILL MAKE NO CHANGES TO WIND HIGHLIGHTS THOUGH WOULD
EXPECT A DECREASE LATER TONIGHT IN THESE AREAS AS WELL.
LIVINGSTON...BIG TIMBER AND NYE HAVE STAYED BELOW ADVISORY
CRITERIA FOR MUCH OF THE DAY BUT WITH STRONGER GUSTS NEARBY WILL
LET THE HIGHLIGHT RIDE A BIT LONGER.
HEAVIEST SNOW HAS ENDED OVER OUR SW MTNS AS MOISTURE PLUME HAS
BEEN PUSHED W-S OF OUR AREA...BUT UNSTABLE NW FLOW IS CONTINUING
TO PRODUCE SNOW SHOWERS WHICH ARE PROBABLY LOCALLY HEAVY. IN
ADDITION...THERE IS A SHORT-LIVED BULGE OF ISENTROPIC ASCENT
LATER TONIGHT INTO MONDAY MORNING AHEAD OF ANOTHER PIECE OF
ENERGY...AND THIS SHOULD ENHANCE THE SNOW SHOWERS ESPECIALLY FOR
NW ASPECTS. WILL LET THE WINTER STORM WARNING RIDE FOR THE
BEARTOOTH ABSAROKAS THRU NOON TOMORROW.
NEXT AREA OF CONCERN IS OUR FAR EAST AS TROWAL WRAPS SOUTHWARD
ACROSS FAR SOUTHEAST MT TOMORROW ON BACK SIDE OF UPPER LOW IN THE
DAKOTAS. LOOKS LIKE A 1-3 INCH SNOWFALL WHICH COMBINED WITH NW
WIND GUSTS OF 35-45 MPH WILL CAUSE SOME BLOWING SNOW AND POOR
TRAVEL CONDITIONS. HAVE ISSUED A WINTER WX ADVISORY TO COVER THIS
FOR FALLON AND CARTER COUNTIES. IMPACTS WILL ALSO BE FELT FURTHER
WEST TOWARD MILES CITY...BROADUS...LAME DEER AND SHERIDAN THOUGH
CURRENT INDICATIONS ARE THAT GREATEST SNOW ACCUMS WILL BE CLOSER
TO THE DAKOTAS BORDER. WIND GUSTS SHOULD EXCEED 50 MPH IN SHERIDAN
TOMORROW...WITH ENHANCEMENT ALONG THE EAST SLOPES OF THE BIGHORN
MOUNTAINS. PCPN IN OUR EAST SHOULD TAPER OFF BY EARLY TUESDAY AS
HEIGHTS BEGIN TO RISE FROM THE WEST.
PERIOD OF DRY WEATHER IS IN STORE TUESDAY AND TUESDAY NIGHT AS
RIDGE BUILDS IN FROM THE WEST. BACKED FLOW ALOFT ALONG WITH LEE
SIDE TROFFING AND COLD AIR IN THE PARK WILL BRING OUR NEXT PERIOD
OF STRONG SW WINDS FOR THE USUAL GAP AREAS.
TEMPS WILL TAKE A STEP DOWN THE NEXT TWO DAYS BUT WILL REMAIN A
LITTLE ABOVE NORMAL WITH HIGHS MOSTLY IN THE 30S TO LOWER 40S.
COOLEST TEMPS WILL BE FELT NEAR THE DAKOTAS BORDER.
JKL
.LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN...
CONSISTENCY IN THE MODELS IS NOT OPTIMAL BUT STILL STRONG ENOUGH
TO START SUPPORTING A DEPICTION OF HOW THE WEATHER WILL UNFOLD
THROUGH THE CHRISTMAS HOLIDAY. WEDNESDAY WILL BE VERY WINDY ACROSS
A LARGE PORTION OF THE REGION AND MILD. WEDNESDAY NIGHT A COLD
FRONT MOVES INTO AFTER THE EVENING HOURS...SOMETIMES BETWEEN 10 PM
AND 4 AM. THIS BRINGS A SHIFT TO MUCH COLDER TEMPERATURES AND
SNOWFALL. THIS SOLUTION IS SUPPORTED BY A BLEND OF LATEST WRF AND
ECMWF AND GFS IS THE OUTLIER. FRONT IS FAST MOVING WITH SHORT
LIVED SNOWFALL CHANCES BUT UPPER LEVEL SUPPORT MOVES OVER THE
FRONTAL ZONE WHICH COULD ALLOW FOR A 2 TO 3 INCH SNOWFALL IN 8
HOURS.
HAVE DRIED OUT WEDNESDAY DAY FORECAST A LITTLE BUT KEPT SNOWFALL
CHANCES FOR WEDNESDAY NIGHT AND CHRISTMAS DAY. FRIDAY IS A QUIETER
DAY WITH COOL NORTHWEST FLOW BUT IT IS MOSTLY DRIER WITH A CHANCE
OF MOUNTAIN SNOW. SATURDAY LOOKS RELATIVELY QUIET TOO BUT AN
ADDITIONAL ROUND OF GAP FLOW WINDS COULD BE SETTING UP LATER ON
SATURDAY NIGHT.
MODELS PICKING UP ON A STRONGER ARCTIC INTRUSION NEXT WEEKEND BUT
NOT CONFIDENT IF ITS SUNDAY OR MONDAY. THIS LOOKS LIKE A MUCH
STRONGER PATTERN CHANGE THAN THE WEDNESDAY NIGHT SYSTEM. BORSUM
&&
.AVIATION...
WINDY CONDITIONS WILL PERSIST INTO MONDAY WITH SOME OCCASIONAL
GUSTS BETWEEN 30 AND 40 KTS. SNOW WILL INCREASE ACROSS EASTERN
MONTANA WHICH WILL LIKELY RESULT IN AREAS OF IFR/LIFR CONDITIONS
IN LOWER CEILINGS AND VISIBILITIES IN SNOW FOR AREAS FROM KMLS
EASTWARD. OTHERWSIE...VFR CONDITIONS WILL PREVAIL. FRIEDERS
&&
.PRELIMINARY POINT TEMP/POPS...
MON TUE WED THU FRI SAT SUN
-----------------------------------------------------------
BIL 034/041 025/039 026/041 029/034 015/030 014/031 015/029
22/W 20/N 02/W 66/S 31/B 11/B 22/S
LVM 031/037 016/034 023/041 028/036 012/029 012/032 018/032
44/J 20/N 03/W 77/S 41/B 12/S 22/S
HDN 031/040 022/037 019/040 025/033 011/029 010/030 010/028
33/J 30/B 02/W 66/S 31/B 11/B 22/S
MLS 029/034 022/035 020/040 025/031 013/027 014/029 009/026
47/J 31/B 13/W 43/S 21/E 12/S 22/S
4BQ 031/034 024/034 017/042 026/035 013/028 012/030 010/028
47/J 62/J 11/E 45/S 21/E 11/B 22/S
BHK 027/030 021/030 015/039 022/030 010/023 012/025 007/022
78/J 62/J 12/W 33/S 21/B 12/S 22/S
SHR 030/037 022/035 018/042 025/033 012/030 011/034 013/030
44/W 41/B 02/W 66/S 31/B 11/B 22/S
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 5
AM MST TUESDAY FOR ZONES 33-37.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
538 PM CST SUN DEC 21 2014
.UPDATE...
ISSUED AT 524 PM CST SUN DEC 21 2014
A LIGHT MIST HAS FORMED ACROSS PORTIONS OF THE FORECAST AREA AND
BASED ON RADAR TRENDS IS EXPANDING IN COVERAGE AREA. IN
ADDITION...FORECAST SOUNDINGS INDICATE THAT THE SATURATED STRATUS
LAYER IS NOW THICKER THAN 1 KM...WHICH IS A SUFFICIENT DEPTH FOR
DRIZZLE FORMATION. THEREFORE...HAVE INTRODUCED DRIZZLE TO THE
FORECAST FOR THE EVENING AND EARLY MORNING HOURS.
SATELLITE IMAGERY INDICATES OVERCAST CONDITIONS ACROSS OUR ENTIRE
FORECAST AREA AND LATEST NAM AND RUC RH FIELDS SHOW LITTLE HOPE
FOR ANY BREAKS IN THE CLOUDS THROUGH THE OVERNIGHT HOURS ACROSS
MOST OF OUR FORECAST AREA. THEREFORE...HAVE INCREASED CLOUD COVER
FOR TONIGHT TO 100 PERCENT CLOUD COVER FOR MOST AREAS EXCEPT FOR
FAR SOUTHWESTERN ZONES WHERE THERE COULD BE A FEW BREAKS IN THE
CLOUDS. BUT EVEN ACROSS SOUTHWESTERN ZONES IT SHOULD STILL BE
MOSTLY CLOUDY TONIGHT.
THE COMBINATION OF CLOUDS...DRIZZLE...AND EVEN LIGHT RAIN LATER
TONIGHT WILL KEEP SURFACE TEMPERATURES NEARLY STEADY THROUGH THE
OVERNIGHT HOURS...WHICH IS SUPPORTED BY MOST FORECAST MODELS.
THEREFORE...INCREASED LOWS FOR TONIGHT BY A FEW DEGREES KEEPING
ALL AREAS ABOVE FREEZING TONIGHT FOR LOWS. THE NEAR SURFACE LAYER
(SFC-875MB) SHOULD BE SUFFICIENTLY WARM BASED ON MODEL FORECAST
SOUNDINGS TO KEEP ALL PRECIPITATION IN THE LIQUID FORM THROUGH THE
OVERNIGHT HOURS.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 349 PM CST SUN DEC 21 2014
SATELLITE AND OBSERVATIONS CONTINUE TO SHOW A VERY PERSISTENT AREA
OF LOW CLOUDS AND FOG OVER PORTIONS OF THE FORECAST AREA. MID LEVEL
CLOUDS FROM THE WEST ARE MOVING INTO THE AREA AND MAKING IT HARDER
TO SEE THE STRATUS...BUT RECENT SATELLITE TRENDS HAS BEEN FOR THE
NORTH/NORTHWEST PROGRESSION OF THE STRATUS HAS SLOWED OR EVEN
STOPPED. DURING THE DAYTIME THE FOG HAS REDUCED VISIBILITY MORE THAN
EARLY THIS MORNING. EVEN WITH GOOD SOUTH WINDS THE FOG HAS SPREAD
ACROSS THE FORECAST AREA. THE SOUTH WINDS HAVE BROUGHT A CONTINUE
STREAM OF MORE MOIST AIR INTO THE REGION WHICH COULD ACCOUNT FOR
SOME OF THE INCREASE IN CLOUDS AND FOG.
A WEAK UPPER LEVEL WAVE MOVED THROUGH THE FORECAST AREA TODAY. THIS
IS HELPING TO BRING IN THE MID LEVEL CLOUDS. AT THE SURFACE THERE IS
A DEVELOPING LOW AND COLD FRONT ON THE HIGH PLAINS. THIS COLD FRONT
IS EXPECTED TO MOVE THROUGH THE FORECAST AREA TONIGHT AS A STRONGER
UPPER LEVEL WAVE APPROACHES THE AREA. PRECIPITATION IS EXPECTED TO
DEVELOP TO THE WEST LATE THIS AFTERNOON AND SPREAD INTO THE AREA
THIS EVENING AND TONIGHT. THE BEST CHANCES FOR PRECIPITATION WILL BE
IN THE NORTH AND IN THE EAST. THE PRECIPITATION SHOULD BE MAINLY OUT
OF THE FORECAST AREA BY MORNING. LOOKING AT FORECAST SOUNDINGS THE
PRECIPITATION SHOULD BE RAIN DURING THE NIGHT TONIGHT. TEMPERATURES
SHOULD REMAIN WARM ENOUGH THAT IT WILL BE LIQUID. THE NORTHWEST HAVE
LOW TEMPERATURES THAT ARE AROUND FREEZING BY MORNING...BUT
PRECIPITATION SHOULD BE OUT OF THERE BEFORE IT ACTUALLY DROPS BELOW
FREEZING.
ON MONDAY THE PRECIPITATION SHOULD BE WRAP AROUND FROM THE UPPER LOW
IN THE DAKOTAS. BY THEN THE TEMPERATURES ALOFT START TO COOL OFF AND
SO THERE WILL BE SOME RAIN AND SNOW MIXED DURING THE MORNING IN THE
NORTH. BY AFTERNOON IT SPREADS A LITTLE FURTHER SOUTH. BY THIS TIME
THE SURFACE TEMPERATURES WARM A LITTLE AS THE TEMPERATURES ALOFT
COOL AND ONCE AGAIN EXPECT A MIX OF RAIN AND SNOW. BY LATE IN THE
AFTERNOON TEMPERATURES COULD BE FALLING IN THE FAR NORTH.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 349 PM CST SUN DEC 21 2014
WE START OFF THE LONG TERM MONDAY NIGHT ON THE BACK SIDE OF A MID-
UPPER CLOSED LOW...ASSOCIATED WITH A DEEPENING LONGWAVE TROUGH AS IT
MOVES TOWARD THE MISSISSIPPI VALLEY. FROM MONDAY NIGHT INTO
TUESDAY/TUESDAY EVENING...WE WILL BE IN A REGION OF LIGHT WRAP
AROUND PRECIPITATION...KEEPING RATHER GLOOMY CONDITIONS AROUND
LONGER. THE TRICKY PART IS FIGURING OUT WHAT GOES ON TUESDAY. MOST
NUMERICAL MODELS ARE PLACING AT LEAST SOME QPF OVER THE CWA...AND
THE NAM/SREF ARE HITTING OUR KANSAS COUNTIES HARDER. THE NAM IS
DISPLAYING .20 INCHES OF QPF AND HAS BEEN CONSISTENT WITH THIS IN
THE PAST COUPLE OF RUNS. THE PROBLEM IS THAT I DO NOT SEE ENOUGH
EVIDENCE TO SUPPORT THE HIGHER CHANCES OF PRECIPITATION ADVERTISED
BY THE SREF ENSEMBLES AND THE NAM QPF. ALL NUMERICAL MODELS SEEM TO
BREAK OFF A SMALL PIECE OF ENERGY THAT WRAPS AROUND THE CLOSED LOW
THAT SHOULD BE LOCATED JUST NORTHEAST OF THE CWA. THIS IS QUITE A
SMALL FEATURE AND IT IS DIFFICULT TO JUDGE WHERE AND IF THIS ENDS UP
ANYWHERE OVER OUR CWA. THERE IS A FAIR AMOUNT OF DOWNGLIDE AND THERE
DOES NOT APPEAR TO BE MUCH SYNOPTIC SCALE LIFT FOR SUPPORT. THERE IS
SOME MID-LEVEL FRONTOGENETIC FORCING FROM THE NAM. THIS WILL BE AN
AREA TO KEEP AN EYE ON. OUR STORM TOTAL SNOW GRID IS GENERALLY IN
THE 1 TO 2 INCH RANGE FOR MONDAY NIGHT/TUESDAY. I HAVE OPTED TO GO A
BIT HIGHER WITH POPS FROM MY NEIGHBORS AND GO WITH 40 POPS...AS I
STILL AM UNCOMFORTABLE WITH WIDE AGREEMENT AMONG MOST NUMERICAL
MODELS THAT WE WILL MEASURE.
WE WILL GET A REPRIEVE FROM PRECIPITATION CHANCES WEDNESDAY...WITH
UPPER LEVEL RIDGING OCCURRING...BUT THIS WILL BE SHORT-LIVED AS
SYNOPTIC FLOW IS PROGRESSIVE. THE TROUGH HITTING THE PACIFIC
NORTHWEST WEDNESDAY EVENING COULD GIVE US A SHOT AT PRECIPITATION AS
EARLY AS THURSDAY AFTERNOON...ESPECIALLY NORTHWEST AS THE TROUGH BY
00Z FRIDAY WILL IS FORECAST TO BE POSITIVELY TILTED FROM THE
NORTHERN GREAT PLAINS TO THE CENTRAL/SOUTHERN ROCKY MOUNTAINS. THIS
QUICK-MOVING WAVE CAN GIVE US A SHOT AT SOME SNOW...BUT AMOUNTS DO
NOT LOOK OVERWHELMING AS THE TROUGH AXIS MAKES ITS WAY EAST OF THE
CWA BY LATE THURSDAY NIGHT...NOT HANGING AROUND LONG ENOUGH FOR
LARGER AMOUNTS. WIND WILL KICK UP BEHIND THE ASSOCIATED COLD FRONT
THURSDAY NIGHT...PROBABLY REDUCING VISIBILITY CHRISTMAS NIGHT FROM
THE BLOWING SNOW. THE WIND WILL CONTINUE TO BE BRISK ON
FRIDAY...CREATING AN UNCOMFORTABLE DAY AFTER CHRISTMAS...WITH COOLER
HIGHS BEHIND THE COLD FRONT NEAR 30 TO THE MID 30S. STILL LOOKS
TROUGHY HEADING INTO THE WEEKEND...SO THE DRY FORECAST IS NOT THE
MOST CONFIDENT. TEMPERATURES WILL BE SEASONABLY COOL.
NUMERICAL MODELS ARE SYNOPTICALLY SIMILAR FOR THE LONG TERM...SO
CONFIDENCE IS FAIRLY HIGH FOR TEMPERATURES AND FOR THE MOST
PART...PRECIPITATION...ALTHOUGH THERE ARE SMALLER SCALE DIFFERENCES
THAT NEED TO BE HAMMERED OUT AS WE APPROACH THEM.
&&
.AVIATION...(FOR THE 00Z KGRI/KEAR TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 524 PM CST SUN DEC 21 2014
LOW CLOUDS...DRIZZLE...AND RAIN WILL BE THE PRIMARY FORECAST
CONCERNS...ESPECIALLY THROUGH THE OVERNIGHT HOURS. ALTHOUGH THE
LOW STRATUS HAS TEMPORARILY BROKEN UP AT KEAR...EXPECT IT WILL
MOVE BACK IN OVER THE NEXT FEW HOURS RESULTING IN IFR CONDITIONS
THROUGH MOST OF THE NIGHT AT BOTH KEAR AND KGRI. DO NOT EXPECT FOG
TONIGHT GIVEN EXPECTED PRECIPITATION AND EVENTUAL CHANGE IN WIND
DIRECTION TO NORTHWESTERLY. HOWEVER...THE LOW CLOUDS SHOULD KEEP
AREA AIRPORTS IN THE IFR CATEGORY ANYWAY UNTIL AROUND MID MORNING.
WILL KEEP THE CLOUDS THROUGH THE DAY ON MONDAY...BUT CLOUD DECK
SHOULD LIFT SOME AS WE GO THROUGH THE MORNING ON MONDAY GETTING US
BACK INTO MORE OF A PREDOMINATELY MVFR ZONE.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...WESELY
SHORT TERM...JCB
LONG TERM...HEINLEIN
AVIATION...WESELY
AREA FORECAST DISCUSSION
NWS HASTINGS NE
339 PM CST SAT DEC 20 2014
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 336 PM CST SAT DEC 20 2014
SATELLITE SHOWS THE AREA OF PERSISTENT STRATUS IN THE EASTERN PART
OF THE FORECAST AREA HAS MOVED LITTLE IN THE PAST COUPLE HOURS BUT
THE THE HIGH CLOUDS MOVING OVER FROM THE WEST THE STRATUS IS
BECOMING MORE DIFFICULT TO SEE. IN THE STRATUS TEMPERATURES CONTINUE
TO STRUGGLE IN THE 30S...BUT AREAS WITH SUNSHINE HAVE WARMED MORE
THIS AFTERNOON.
MAIN CONCERN WITH THIS PERIOD ONCE AGAIN IS THE FOG CHANCES FOR
TONIGHT. A WEAK UPPER LEVEL WAVE MOVES THROUGH THE FORECAST AREA
LATE TONIGHT INTO SUNDAY. WITH THIS EXPECT THERE TO BE SOME HIGHER
CLOUDS THAT MOVE INTO THE AREA...BUT DRY CONDITIONS ARE EXPECTED.
THE LOW LEVEL MOISTURE CONTINUES ACROSS MUCH OF THE AREA THROUGH THE
NIGHT AND INTO SUNDAY. THE STRATUS SEEMS TO BE THE MOST PERSISTENT
IN THE NORTHEAST PART OF THE FORECAST AREA. THE RAP RELATIVE
HUMIDITY AT 925MB HAS BEEN FOLLOWING THE STRATUS THE BEST THIS
AFTERNOON AND THROUGH MOST OF THE NIGHT THE NORTHEAST REMAINS WITH
CLOUDS. IN THE SOUTHEAST THE HIGHER RELATIVE HUMIDITY BUILDS BACK
INTO THE AREA LATE TONIGHT. EXPECT THERE COULD BE SOME FOG NEAR THE
EDGES OF THE STRATUS. WILL KEEP PATCHY FOG ACROSS ALL BUT THE FAR
WEST AND AREAS OF FOG IN THE EAST WHERE THERE IS THE BEST CHANCE FOR
FOG SINCE VISIBILITY AT KJYR STILL HAS LOW VISIBILITY. ONCE AGAIN
THERE IS A POTENTIAL FOR SOME LOWER VISIBILITIES LATE TONIGHT INTO
SUNDAY MORNING AND EXPECT THE EAST IS THE BEST CHANCE.
BY SUNDAY MORNING THE WINDS WILL INCREASE A LITTLE BIT FROM THE
SOUTH. THIS WILL HELP TO MIX THINGS UP A BIT AND THE FOG AND STRATUS
MAY FINALLY MOVE OUT OF THE AREA.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 336 PM CST SAT DEC 20 2014
THE BIGGEST CHALLENGE WILL BE DETERMINING PRECIPITATION CHANCES.
WE KICK OFF THE LONG TERM SUNDAY NIGHT WITH A LONGWAVE TROUGH AXIS
OVER THE GREAT PLAINS...AS A STRONG JET HEADS IN ON THE BACKSIDE OF
THE TROUGH..FROM THE PACIFIC NORTHWEST INTO THE GREAT BASIN. MOST OF
THE ENERGY IS ASSOCIATED WITH THE CLOSED LOW IN THE NORTHERN
PLAINS...SO I AM NOT GOING ALL THAT HIGH WITH CHANCES HERE. A
SMALLER SHORTWAVE TROUGH WITHIN THE LONGWAVE TROUGH WILL HELP KICK
SOMETHING UP IN THE EVENING...THE WAY IT LOOKS NOW...BUT SMALL
FEATURES ARE DIFFICULT TO BE VERY EXACT WITH TIMING. KEEPING THIS
ALL RAIN AS TEMPERATURES DO NOT APPEAR TO BECOME COLD ENOUGH BEFORE
THE PRECIPITATION EXITS WITH THIS PERTURBATION. ANOTHER PERTURBATION
WORKS AROUND THE TROUGH BY MONDAY NIGHT/TUESDAY. TEMPERATURE
PROFILES APPEAR TO SUPPORT SOME LIGHT SNOW MONDAY NIGHT INTO
TUESDAY. PRECIPITATION/SNOW AMOUNTS ARE EXPECTED TO BE LIGHT...WITH
SNOW ACCUMULATION NO MORE THAN AN INCH ANTICIPATED WITH THIS NEXT
PIECE OF ENERGY. AGAIN...CONFIDENCE IS NOT THE HIGHEST WITH
EXACT TIMING.
FLOW IS QUITE PROGRESSIVE AND YET ANOTHER TROUGH MAKES ITS WAY INTO
THE ROCKIES. A PIECE OF ENERGY IS EXPECTED TO BREAK OFF AHEAD OF THE
MAIN WAVE...BUT LOOKS MORE FOCUSED JUST NORTH OF THE CWA. WE COULD
GET SOME SNOW OUT OF THIS...BUT AGAIN...DOES NOT LOOK LIKE WE WILL
GET A LOT OUT OF SNOW. WE SHOULD GET A NOTICEABLE COOL DOWN FRIDAY
BEHIND THE ASSOCIATED COLD FRONT. HIGHS WILL ONLY BE IN THE LOWER TO
MID 30S AND THE WIND COULD BE QUITE GUSTY FROM THE
NORTHWEST...MAKING THE DAY AFTER CHRISTMAS POTENTIALLY BRISK AND
UNCOMFORTABLE.
&&
.AVIATION...(FOR THE 18Z KGRI/KEAR TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1127 AM CST SAT DEC 20 2014
FOG CONTINUES TO BE PERSISTENT IN THE KGRI TERMINAL AREA.
SATELLITE HAS NOT SHOWN ANY EASTWARD MOVEMENT OF THE CLOUDS AND
VISIBILITY HAS CONTINUED TO BE AT 1/4 MILE OR LESS. WILL KEEP WITH
PERSISTENCE FOR A COUPLE MORE HOURS THEN BELIEVE THAT THE
VISIBILITY WILL IMPROVE...BUT NOT ESCAPE THE LOW CLOUDS AND FOG.
IF IT DOES NOT MOVE OUT THIS AFTERNOON EXPECT THAT IT WILL RETURN
AS THE SUN GOES DOWN TONIGHT. KEAR TERMINAL HAS A LITTLE LIGHT FOG
THAT SHOULD IMPROVE THIS AFTERNOON AS WELL. THE HIGH CLOUDS MOVING
IN SHOULD KEEP THE FOG AND LOW CLOUDS OUT OF THE AREA.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...JCB
LONG TERM...HEINLEIN
AVIATION...JCB
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1209 AM CST SAT DEC 20 2014
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 238 PM CST FRI DEC 19 2014
SATELLITE AND OBSERVATIONS SHOW THE EDGE OF THE LOW CLOUDS IN THE
FAR WESTERN PART OF THE FORECAST AREA. FOG HAS BEEN PERSISTENT NEAR
THE EDGE OF THE LOW CLOUDS. VISIBILITIES HAVE IMPROVED IN THE PAST
HOUR OR SO...BUT SOME LIGHT FOG PERSISTS.
WATCHING THE VERY SLOW PROGRESSION OF THE CLOUDS TO THE EAST HAVE
BEEN INCLINED TO KEEP THE CLOUDS LONGER THAN EARLIER THOUGHT. UNDER
THE CLOUDS THE WINDS ARE FROM THE SOUTH OR EVEN THE SOUTHEAST A BIT
AND THIS HAS MADE IT HARD FOR THE CLEARING LINE TO CONTINUE MOVING
TO THE EAST. ON THE OTHER HAND UNDER THE CLEAR SKIES THE WINDS ARE
FROM THE WEST AND SHOULD BE PUSHING DRIER AIR DOWN SLOPE WHICH
SHOULD HELP THE CLEARING. AT THIS TIME THE SOUTH WINDS SEEM TO BE
WINNING THAT BATTLE.
TWO MAIN QUESTIONS REMAIN FOR THE FORECAST. FIRST HOW FAR EAST WILL
THE CLOUDS MOVE AND SECOND WHETHER THERE WILL BE FOG NEAR THE EDGE
OF THE STRATUS. A BROAD SURFACE TROUGH JUST TO THE WEST OF THE
FORECAST AREA WILL MOVE TO THE EAST DURING THE NIGHT. THIS SHOULD
HELP WINDS TO TURN TO THE WEST EVEN THOUGH THEY SHOULD BE LIGHT.
EXPECT THAT THE WEST WINDS WILL HELP TO PUSH THE CLOUDS TO THE EAST
A LITTLE DURING THE NIGHT. CLOUDS SHOULD HOLD TOUGH IN THE
EAST...BUT THE WEST ESPECIALLY AND EVEN THE CENTRAL PART OF THE
FORECAST AREA COULD SEE SOME CLEARING DURING THE NIGHT. THAT BRINGS
WITH IT THE COOLING TEMPERATURES THAT HAVE BEEN EVIDENT IN THE WEST
DURING THE MORNING TODAY. COOLER TEMPERATURES AND LIGHT WINDS SHOULD
ALLOW FOR SOME FOG ACROSS THE AREA. HOW MUCH...WHERE AND HOW LOW
WILL BE VISIBILITY BE ARE ALL QUESTIONS THAT PROVIDE A CHALLENGE.
SINCE MANY LOCATIONS ACROSS THE FORECAST AREA HAVE YET VISIBILITY OF
MORE THAN 5 MILES...WILL MAKE THE ASSUMPTION THAT THE LIGHT FOG
SHOULD LIFT A LITTLE THIS AFTERNOON...BUT RETURN DURING THE NIGHT.
HAVE KEPT PATCHY FOG ACROSS THE FORECAST AREA LATE TONIGHT. THE
LOWEST VISIBILITIES WILL BE NEAR THE EDGE OF THE CLOUDS. CURRENTLY
THE NAM AND HRRR ARE THE ONLY MODELS THAT INDICATE THERE WOULD BE
SOME FOG AROUND THE AREA. THE NAM KEEPS IT FURTHER TO THE EAST AND
FAIRLY LIGHT WHILE THE HRRR GIVES SOME LOWER VISIBILITIES FURTHER
WEST. WITH THE CURRENT FORECAST FOR WHERE THE CLEARING LINE WILL BE
LATE TONIGHT EXPECT THE LOWEST VISIBILITIES TO BE IN THE CENTRAL
PART OF THE FORECAST AREA BUT NOT SURE HOW LOW THE VISIBILITY WILL
BE...ALTHOUGH WITH THE PAST FEW NIGHTS AS A MODEL EXPECT THERE COULD
BE SOME VISIBILITIES LESS THAN A MILE SOMEWHERE.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 238 PM CST FRI DEC 19 2014
A PROGRESSIVE WEST NORTHWESTERLY FLOW IS EXPECTED TO BE IN PLACE
ACROSS THE REGION TO START THE EXTENDED PERIODS...WITH AN UPPER
LEVEL SHORTWAVE ACROSS THE PACIFIC NORTHWEST FORECAST TO DIVE INTO
THE PLAINS SUNDAY NIGHT THROUGH MONDAY. AS THIS DISTURBANCE DEEPENS
ACROSS THE MISSISSIPPI RIVER VALLEY AND TRACKS INTO THE GREAT LAKES
REGION...NORTHWESTERLY FLOW WILL PERSIST ALOFT...AND COULD SEE
ANOTHER UPPER LEVEL WAVE DIVE ACROSS THE LOCAL AREA TUESDAY NIGHT OR
WEDNESDAY. WHILE MODELS DISAGREE ON THE TIMING OF THIS NEXT
WAVE...THEY DIVERGE EVEN MORE AS WE TRANSITION INTO CHRISTMAS DAY
AND BEYOND...WITH THE EC STILL MAINTAINING A MUCH BROADER TROUGH
ACROSS THE WESTERN STATES AND THE GFS KEEPS THIS NEXT DISTURBANCE
MUCH FURTHER NORTH. DUE TO THE DIVERGENCE OF THE GUIDANCE...BLENDED
FORECAST DROPPED POPS FOR CHRISTMAS NIGHT AND THE DAY AFTER...AND
GIVEN THE UNCERTAINTY...SAW NO REASON TO TINKER WITH THE CHANCE OF
SNOW FOR THE TIME BEING.
STARTING OFF SUNDAY...EXPECT THE LOW LEVEL STRATUS THAT HAS BEEN
PERSISTENT ACROSS THE LOCAL AREA FOR MUCH OF THE LAST 10 DAYS TO BE
EAST OF THE LOCAL AREA AND CLOSER TO THE MISSOURI RIVER IN RESPONSE
TO A SURFACE TROUGH SLOWLY PUSHING ACROSS THE CENTRAL PLAINS. WITH
THE FOCUS OF SOME FOG ON THE WESTERN EDGE OF THIS STRATUS THE PAST
FEW DAYS...THINK IT IS PROBABLE THAT WE MIGHT STILL SEE SOME FOG
FROM ROUGHLY HIGHWAY 281 EASTWARD TO START THE DAY SUNDAY...CLOSER
TO THE EDGE OF THE STRATUS. AS A RESULT OF THIS...OPTED TO INTRODUCE
PATCHY FOG TO THE FORECAST FOR THIS AREA SUNDAY MORNING.
THEREAFTER...THE SURFACE FLOW IS EXPECT TO SHIFT AND BECOME MORE
WESTERLY THROUGH THE DAY SUNDAY...AND THIS DOWNSLOPING COMPONENT OF
THE WIND COMBINED WITH AT LEAST PARTLY SUNNY SKIES...SHOULD MAKE FOR
A RELATIVELY NICE FINISH TO THE WEEKEND...WITH TEMPERATURES EXPECTED
TO CLIMB INTO THE 40S SUNDAY AFTERNOON.
BEHIND THE SURFACE TROUGH...EXPECT THE NEXT UPPER LEVEL DISTURBANCE
TO SLIDE ACROSS THE LOCAL AREA LATE SUNDAY NIGHT INTO
MONDAY...BRINGING MAINLY THE CHANCE FOR RAIN TO THE LOCAL AREA.
BRIEFLY CONTEMPLATED INTRODUCING A RAIN SNOW MIX FOR THE EARLY
MORNING HOURS MONDAY GIVEN SURFACE TEMPS NEAR FREEZING...BUT LOOKING
AT THE ATMOSPHERIC PROFILE AND WARM LAYER ALOFT...THIS THE IS LIKELY
TO BE MAINLY A LIGHT RAIN EVENT FOR THE MAJORITY OF THE AREA. AS THE
MAIN UPPER LEVEL LOW MOVES INTO THE MISSISSIPPI RIVER VALLEY MONDAY
AFTERNOON...EXPECT SOME WRAP AROUND MOISTURE TO POTENTIALLY CLIP THE
NORTHERN AND EASTERN PORTIONS OF THE FORECAST AREA MONDAY NIGHT INTO
TUESDAY...WITH A LIGHT DUSTING OF SNOW POSSIBLE OVER THIS PERIOD. AS
THE FLOW REMAINS NORTHWESTERLY ALOFT BEHIND THE DEPARTING SYSTEM...A
SECONDARY UPPER LEVEL WAVE IS PROGGED TO CROSS THE NORTHERN AND
CENTRAL PLAINS TUESDAY NIGHT OR WEDNESDAY. DUE TO DIFFERENCES IN
GUIDANCE...THE CONFIDENCE OF ANY PRECIP OVER THIS PERIOD IS LOW AND
KEPT TEMPERATURES SEASONAL AND FORECAST DRY TUESDAY NIGHT THROUGH
CHRISTMAS DAY AS A RESULT.
THEREAFTER...WHAT LOOKED LIKE A DECENT CHANCE FOR SNOW LATE IN THE
EXTENDED PERIODS APPEARS A BIT MORE IN QUESTION THIS AFTERNOON AS
SIGNIFICANT DIFFERENCES IN THE HANDLING OF THE NEXT SYSTEM ARE
APPARENT. AS A RESULT...AS PREVIOUSLY MENTIONED...SAW NO REASON TO
DIVERGE FROM BLENDED FORECAST AS CONFIDENCE IN ANY ONE PARTICULAR
SOLUTION IS LOW THIS FAR OUT.
&&
.AVIATION...(FOR THE 06Z KGRI/KEAR TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1209 AM CST SAT DEC 20 2014
LIFR TO VLIFR CONDITIONS TO START THE TAF PERIOD...WITH IMPROVING
CONDITIONS THEN EXPECTED DURING THE DAY SATURDAY.
A PERSISTENT STRATUS DECK CONTINUES ACROSS THE REGION...ALTHOUGH
THE WESTERN PERIPHERY OF THIS CLOUD DECK IS CURRENTLY LOCATED VERY
NEAR KEAR AND MOVING EAST. UNFORTUNATELY...AND AXIS OF DENSE FOG
HAS DEVELOPED ALONG AND JUST AHEAD OF THIS CLEARING LINE AND AS A
RESULT...SIGNIFICANT VISIBILITY RESTRICTION CONTINUES AT BOTH KEAR
AND KGRI. RECENT SATELLITE TRENDS AND GUIDANCE SUGGEST THIS
STRATUS SHIELD WILL SLOWLY DRIFT EAST THIS MORNING AND INTO THE
DAY SATURDAY...THUS ALLOWING FOR IMPROVING CONDITIONS DURING THE
SATURDAY. IN FACT...VFR CONDITIONS ARE CURRENTLY FORECAST AT KEAR
BY 12Z...AND AT KGRI BY 14Z. UNTIL THAT POINT HOWEVER...EXPECT THE
LIFR TO VLIFR CONDITIONS TO CONTINUE. THE SURFACE WIND WILL REMAIN
LIGHT AND VARIABLE TO START THE TAF PERIOD...BUT BECOME MORE
ESTABLISHED FROM THE SOUTH/SOUTHWEST DURING THE DAY SATURDAY.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR NEZ039>041-
046>048-061>063-074>076-084>086.
KS...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR KSZ006-007.
&&
$$
SHORT TERM...JCB
LONG TERM...ROSSI
AVIATION...BRYANT
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
955 PM PST FRI DEC 19 2014
.SYNOPSIS...A WEAK SYSTEM WILL MOVE ACROSS THE AREA THROUGH SATURDAY
WITH JUST A FEW SHOWERS POSSIBLE IN THE SIERRA AND THE HIGHER
ELEVATIONS OF THE SOUTHERN GREAT BASIN. THE REMAINDER OF THE AREA
WILL SEE AN INCREASE IN HIGH CLOUDS. HIGH PRESSURE IS EXPECTED TO
STRENGTHEN OFF THE COAST OF CALIFORNIA ON SUNDAY AND HOLD THROUGH
TUESDAY KEEPING THE AREA DRY AND MILD. ANOTHER SYSTEM MAY IMPACT THE
AREA CHRISTMAS EVE INTO CHRISTMAS DAY.
&&
.UPDATE...ONCE AGAIN WE HAVE SOME VERY CLOSE TEMP-DEWPOINT SPREADS
AT THE SURFACE THIS EVENING ACROSS MOHAVE COUNTY WITH COLORADO CITY
SHOWING SATURATED CONDITIONS. WINDS ARE LIGHT AND THE LOW-LEVEL
MOISTURE IN PLACE IS NOT GOING TO GO ANYWHERE OVERNIGHT. THE MAIN
FACTOR AGAINST ANY FOG TONIGHT WOULD BE THE CIRRUS PASSING OVERHEAD.
OBSERVATIONS AROUND DAYBREAK FRIDAY (TODAY) SHOWED MAINLY A LOW
STRATUS DECK DEVELOPED. BUFKIT SOUNDINGS FROM THE RAP ARE NOT TOO
FAVORABLE FOR MUCH IN THE WAY OF FOG TONIGHT AT KINGMAN, BUT I
SUSPECT THAT WE COULD SEE AT LEAST A FEW PATCHES OF FOG OR LOW
STRATUS CLOUDS DEVELOP ESPECIALLY IN THE AREA IN AND AROUND COLORADO
CITY OVERNIGHT OR AFTER DAYBREAK SATURDAY. I WENT AHEAD AND ADJUSTED
THE GRIDS FOR THIS AS WELL AS ADJUSTED UP DEWPOINTS FOR TONIGHT
BASED ON THE LATEST OBSERVATIONS. THE REST OF THE FORECAST LOOKS ON
TRACK FOR NOW, ALTHOUGH SOME ADJUSTMENTS TO POPS MAY BE NEEDED FOR
SATURDAY IN LINCOLN COUNTY AS THE LATEST MODELS SHOW A BIT MORE QPF
IN THE PANHANDLE.
&&
.AVIATION...FOR MCCARRAN...WINDS SHOULD BE 6 KTS OR LESS AND FAVOR
TYPICAL DIURNAL DIRECTIONAL TRENDS. MAINLY BKN CLOUDS AOA 20K FEET
WITH FEW-SCT CLOUDS AS LOW AS 15K FEET OVERNIGHT AND AS LOW AS 10K
FEET ON SATURDAY.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...WINDS WILL BE 6 KTS OR LESS AND TREND TOWARD TYPICAL
DIURNAL DIRECTIONS. A FEW SHOWERS WILL BE POSSIBLE ACROSS THE HIGHER
ELEVATIONS OF INYO, ESMERALDA, CENTRAL NYE AND NORTHERN LINCOLN
COUNTIES THROUGH SATURDAY. CIGS AS LOW AS 6K-8K FEET IN AND NEAR ANY
SHOWERS OTHERWISE EXPECT MAINLY BKN CLOUDS AOA 20K FEET WITH A FEW
CLOUDS AS LOW AS 10K-12K FEET.
&&
.PREVIOUS DISCUSSION...
ISSUED AT 300 PM PST FRI DEC 19 2014
DISCUSSION...
ANY SHOWERS THAT DO FALL ARE EXPECTED TO REMAIN LIGHT AND ANY UPPER
ELEVATIONS SNOWFALL /ABOVE 6500 FEET/ WILL REMAIN WELL BELOW
ADVISORY LEVELS. THIS SYSTEM WILL CONTINUE TO PUSH EAST TONIGHT
WITH ONLY A SLIGHT CHANCE OF SHOWERS FOR ESMERALDA...CENTRAL NYE AND
NORTHERN LINCOLN COUNTIES. HIGH PRESSURE WILL START TO STRENGTHEN
OVER THE EASTERN PACIFIC LATE SATURDAY AND SLOWLY DRIFT EAST BY
SUNDAY. A DRIER NORTHWEST FLOW WILL SET UP OVER THE AREA THROUGH
MONDAY...BUT SURFACE HIGH PRESSURE IS FORECAST TO BUILD OVER IDAHO
AND MOVE INTO WYOMING MONDAY EVENING AND TUESDAY. THIS WILL CAUSE
THE SURFACE GRADIENT TO INCREASE DOWN THE COLORADO RIVER VALLEY AND
BRING SOME GUSTY NORTH WINDS TO THE AREA...ESPECIALLY AROUND
LAUGHLIN/BULLHEAD CITY. BY TUESDAY AFTERNOON THE HIGH PRESSURE RIDGE
WILL MOVE OVER THE AREA BRINGING LIGHT WINDS AND ABOVE NORMAL
TEMPERATURES. READINGS BY MID WEEK MAY BE AS HIGH AS 10 DEGREES
ABOVE NORMAL. HOWEVER...SURFACE INVERSIONS MAY HELP KEEP THOSE
NUMBERS DOWN A LITTLE. BEYOND WEDNESDAY GETS A LITTLE TRICKY AS THE
GFS/ECMWF DIFFER ON A POTENTIAL TROUGH MOVING INTO THE AREA ON
CHRISTMAS DAY. IT DOES LOOK LIKE WINDS WILL START TO INCREASE
WEDNESDAY AFTERNOON...WHICH WILL LIKELY MAKE WEDNESDAY THE WARMEST
DAY OF NEXT WEEK AND THEN A COLD FRONT WILL MOVE THROUGH ON
THURSDAY. HOWEVER...THE STRENGTH OF THE FRONT AND HOW FAR SOUTH THIS
SYSTEM DIGS IN ALSO IN QUESTION. FOR NOW IT DOES LOOK LIKE WE WILL
SEE SOME WINDIER AND COOLER WEATHER ON CHRISTMAS WITH THE POTENTIAL
OF SHOWERS AT LEAST ACROSS NORTHERN AND CENTRAL NEVADA. &&
.SPOTTER INFORMATION STATEMENT...SPOTTER ACTIVATION IS NOT EXPECTED.
&&
$$
UPDATE/AVIATION....STACHELSKI
PREVIOUS...GORELOW
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
656 PM EST SUN DEC 21 2014
.SYNOPSIS...
AS A LOW PRESSURE SYSTEM MOVES EAST OF THE AREA THIS
EVENING...LIGHT SNOW WILL COME TO AN END WITH CLOUDS LINGERING
OVER THE ENTIRE AREA TONIGHT. DRY WEATHER IS EXPECTED ON
MONDAY...BUT A SOUTH TO SOUTHEAST LOW LEVEL FLOW MONDAY NIGHT INTO
TUESDAY WILL BRING MOISTURE INTO THE REGION AND A LIGHT WINTRY MIX
OF PRECIPITATION WILL BE POSSIBLE. EVENTUALLY THE PRECIPITATION
CHANGES TO ALL RAIN TUESDAY NIGHT WITH WIDESPREAD RAIN ON
CHRISTMAS EVE ALONG WITH WINDY CONDITIONS.
&&
.NEAR TERM /UNTIL 7 AM MONDAY MORNING/...
AS OF 656 PM EST SUNDAY...OTHER THAN A FEW FLURRIES HERE AND
THERE...VARIABLY CLOUDY SKIES EXPECTED ALONG WITH SEASONABLY COLD
TEMPERATURES. SOME BREAKS POSSIBLE HERE AND THERE OVERNIGHT...ESP
IN THE ST LAWRENCE VALLEY PER SATELLITE TRENDS AND 1 KM AGL RAP RH
PROGS. MINOR ADJUSTMENTS TO SKY/TEMPS TO ACCOUNT FOR CURRENT
TRENDS...BUT MAINLY NOISE LEVEL ADJUSTMENTS WITH CURRENT FORECAST
IN GOOD SHAPE. PRIOR DISCUSSION FOLLOWS. HAVE A GREAT EVENING.
PRIOR DISCUSSION FROM 339 EST SUNDAY...
LIGHT SNOW ASSOCIATED WITH A SMALL UPPER LEVEL LOW PRESSURE
SYSTEM IS GRADUALLY COMING TO AN END ACROSS SOUTH CENTRAL VERMONT
THIS AFTERNOON WITH JUST CLOUDY SKIES EXPECTED OVERNIGHT. THE
CLOUDS WILL KEEP OVERNIGHT LOWS IN THE TEENS TO LOWER 20S.
&&
.SHORT TERM /7 AM MONDAY MORNING THROUGH WEDNESDAY/...
AS OF 339 PM EST SUNDAY...QUIET WEATHER IS EXPECTED ON MONDAY
WITH HIGH PRESSURE OVER THE AREA AND SLIGHTLY WARMER TEMPERATURES
WITH HIGHS IN THE MID 20S TO LOWER 30S. THE MAIN CONCERN IN THE
SHORT TERM WILL TAKE PLACE MONDAY NIGHT INTO TUESDAY AS LOW LEVEL
FLOW TURNS MORE TO THE SOUTH AND SOUTHEAST. THIS WILL BRING
ATLANTIC MOISTURE INTO THE REGION. AT THE SAME TIME...THE FLOW
ALOFT BECOMES MORE SOUTH AND SOUTHWEST WITH WARM AIR ADVECTION
TAKING PLACE. THIS WILL SET UP A THERMAL PROFILE CONDUCIVE TO
MIXED PRECIPITATION. PRECIPITATION AMOUNTS WILL BE LIGHT...BUT
NEVERTHELESS SOME LIGHT FREEZING RAIN IS EXPECTED ESPECIALLY OVER
THE SOUTHERN PORTIONS OF THE AREA. EVENTUALLY THE PRECIPITATION
BECOMES ALL RAIN TUESDAY NIGHT WITH STEADIER RAIN AND WIND STILL
NOT EXPECTED UNTIL WEDNESDAY.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 357 PM EST SUNDAY...LATEST GUIDANCE STILL SUPPORTS THE IDEA
OF RAINY AND POSSIBLY WINDY CONDITIONS ON CHRISTMAS EVE DAY INTO
THE MORNING HOURS OF CHRISTMAS DAY.
WEDNESDAY MORNING THE PRECIPITATION CHANCE INCREASES QUICKLY AS
THE UPPER LEVEL TROUGH DEEPENS OVER THE MIDWEST. A PULSE OF ENERGY
WILL SLIDE UP THE TROUGH AND THEN LIFT OVER THE NORTHEAST BRINGING
CATEGORICAL CHANCES FOR RAINFALL ON CHRISTMAS EVE. THE
STRENGTHENING SOUTHWEST FLOW WILL BE SHIFTING MORE TOWARDS
SOUTHERLY FLOW AHEAD OF THE TROUGH. THAT WILL CONTINUE THE
MOISTURE ADVECTION INTO THE LOW LEVELS WHICH WILL AID IN THE
DEVELOPMENT OF A PERSISTENT RAIN EVENT ON WEDNESDAY. THE LONG TERM
GUIDANCE HAS CONTINUED THE TREND OF WEAKENING THE 850MB JET OVER
THE REGION AND DEVELOP THE SYSTEM AS MORE OF A STRONG OPEN WAVE
INSTEAD OF A CLOSED LOW. THIS WILL STILL PROVIDE FOR CHANCES OF
30-40 MPH GUSTS BUT WITHOUT THE EASTERN COMPONENT THE CHANCES OF
STRONG DOWNSLOPE WIND GUSTS ARE WEAKENING. THE BIGGEST AREA OF
CONCERN FOR LOCALIZED HIGH WINDS CONTINUES TO BE OVER THE HIGHER
TERRAIN AND PERHAPS ALONG THE WESTERN SLOPES OF THE GREENS AND THE
ADIRONDACKS.
AS FAR AS QPF AMOUNTS FOR THIS SYSTEM...WE STILL EXPECT TOTAL
AMOUNTS TO RANGE FROM 1 TO 2 INCHES ACROSS MUCH OF THE REGION.
AMOUNTS WILL VARY A BIT DUE SHADOWING IN SOME AREAS AND OROGRAPHIC
ENHANCEMENT IN OTHERS. HIGHEST TOTALS LIKELY ALONG SOUTH FACING
SLOPES OF SOUTHERN GREENS AND ADIRONDACKS...WITH LIGHTER AMOUNTS OVER
NORTHWEST VERMONT AND FAR NORTHERN NEW YORK. THE GUIDANCE HAS BEEN
FAIRLY CONSISTENT THAT SOUTHERN VERMONT AND THE COASTAL AREAS OF
NEW ENGLAND WOULD SEE MORE RAINFALL FOR THIS EVENT. FLOODING STILL
CONTINUES TO REMAIN A POTENTIAL ISSUE WITH THIS SYSTEM. WITH
TEMPS ON WEDNESDAY EXPECTED TO REACH INTO THE UPPER 40S AND LOWER
50S...AND LITTLE DROP OFF WEDNESDAY NIGHT...THE COMBINATION OF
RAIN AND MILD TEMPS WILL RESULT IN SIGNIFICANT SNOWMELT. THE
SNOWMELT COMBINED WITH THE 1-2 INCHES OF RAIN COULD CAUSE SOME
LOCALIZED FLOODING IN AREAS OF POOR DRAINAGE AND IN SMALL STREAMS.
RIGHT NOW RIVER GAUGES ARE SHOWING RIVER LEVELS ARE QUITE LOW...SO
WHILE SOME MINOR FLOODING WILL BE POSSIBLE WE DON`T EXPECT
SIGNIFICANT RIVER FLOODING ISSUES.
RAIN CONTINUES EARLY ON CHRISTMAS DAY...THEN SOME DRYING EXPECTED WITH
PASSAGE OF COLD FRONT DURING THE MORNING. LINGERING SHOWERS WILL
CONTINUE DURING THE AFTERNOON...AND WILL TRANSITION TO SNOW
SHOWERS OVER THE HIGHER TERRAIN AS COLDER AIR RETURNS. TEMPS IN
VALLEYS REMAIN MILD THOUGH FOR MUCH OF THE DAY WITH READINGS IN
THE 40S.
DRIER CONDITIONS EXPECTED FOR THURSDAY NIGHT AND FRIDAY...WITH
JUST SOME LINGERING MOUNTAIN SNOW SHOWERS. SHORTWAVE TROUGH BRINGS
A WEAK CHANCE OF SNOW/RAIN SHOWERS TO THE ENTIRE REGION SATURDAY.
TEMPERATURES FRIDAY AND SATURDAY ARE EXPECTED TO REMAIN ABOVE
NORMAL WITH HIGHS EACH DAY IN THE MID 30S TO AROUND 40.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
THROUGH 00Z TUESDAY...GENERAL IDEA OF MVFR TO IFR CONDITIONS DUE
TO LOW CEILINGS AND OCCASIONAL MIST. VERY LIGHT WINDS (UNDER 10
KNOTS) AND SATURATED RH CONDITIONS THROUGH A DEEP DEPTH OF THE
ATMOSPHERE WILL FAVOR PERIODS OF MIST AT MOST OF THE TERMINALS
OVERNIGHT. WHILE CEILINGS WILL PREDOMINANTLY BE MVFR THROUGH MOST
OF THE PERIOD...IFR CEILINGS WILL ALSO EXIST BUT BE MOST FAVORED
AT MSS OVERNIGHT. ANY MIST WILL BURN OFF INTO MONDAY MORNING AS
WEAK INVERSION DISSIPATES BUT STILL EXPECT THERE TO BE PLENTY OF
MVFR CEILINGS AROUND. PRECIPITATION THEN APPROACHES FROM THE SOUTH
LATE IN THE TAF PERIOD WITH VCSH INDICATED AT RUT. ANY
PRECIPITATION THAT SHOULD INITIALLY FALL WOULD BE IN THE FORM OF
LIGHT SNOW, BUT BE MORE LIKELY AFTER 00Z ELSEWHERE.
OUTLOOK 00Z TUESDAY THROUGH THURSDAY...
00Z TUE-12Z WED...PERIODS OF MVFR IN LIGHT MIXED PRECIPITATION.
12Z WED-18Z THU...PERIODS OF MVFR/IFR IN RAIN. GUSTY WINDS POSSIBLE.
18Z THU-00Z FRI...MOSTLY VFR WITH MVFR POSSIBLE IN SCATTERED
RAIN/SNOW SHOWERS.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...EVENSON
NEAR TERM...JMG/EVENSON
SHORT TERM...EVENSON
LONG TERM...DEAL
AVIATION...LOCONTO/DEAL
AREA FORECAST DISCUSSION
NWS BISMARCK ND
935 PM CST SUN DEC 21 2014
.UPDATE...
ISSUED AT 928 PM CST SUN DEC 21 2014
WIDESPREAD FOG WITH VISIBILITIES BETWEEN ONE HALF AND 2 MILES COVER
CENTRAL AND EASTERN NORTH DAKOTA. ONLY MINOT AFB SHOWING SOME
FREEZING DRIZZLE AT 9 PM CST. WILL DELAY THE FREEZING DRIZZLE
SOUTH CENTRAL AND EAST CENTRAL FOR THE EVENING INTO THE OVERNIGHT
HOURS BUT EVENTUALLY SOME SHOULD SHOW UP. WILL KEEP MENTION OF
FREEZING DRIZZLE NORTH CENTRAL WHERE AT LEAST MINOT AFB IS SHOWING
SOME. STILL RAINING SOUTHWEST WITH TEMPERATURES ACROSS THE AREA
STILL IN THE MID/UPPER 30S. STILL WAITING FOR COOLER AIR TO ARRIVE
FOR THE CHANGEOVER TO SNOW WEST WHICH SHOULD HAPPEN AFTER
MIDNIGHT.
UPDATE ISSUED AT 637 PM CST SUN DEC 21 2014
COMPLEX WINTER WEATHER PATTERN BEGINNING AS RAIN ACROSS THE WEST
THIS EVENING.LOW STRATUS AND FOG CONTINUE ACROSS THE CENTRAL AND
EAST. THE POTENTIAL FOR FREEZING DRIZZLE REMAINS THERE. BASED ON
CURRENT TRENDS THE FORECAST IS OK SO FAR. WINTER WEATHER ADVISORY
BEGINS AT 06Z/11PM MST SOUTHWEST THIS EVENING.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 312 PM CST SUN DEC 21 2014
FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE
PLENTIFUL...RAIN CHANGING TO SNOW WEST THIS EVENING WITH
ACCUMULATIONS AND INCREASING WIND INTO MONDAY...AREAS OF FOG AND
PATCHY FREEZING DRIZZLE EAST...AND MORE ACCUMULATING SNOW
SOUTHEAST DEVELOPING MONDAY MORNING AND AFTERNOON.
CURRENTLY...INCOMING STORM SYSTEM ON THE NOSE OF A POWERFUL 150KT
+ UPPER LEVEL JET STREAK NOW OVER THE NORTHERN ROCKIES. ASSOCIATED
SURFACE LOW DEVELOPING AND MOVING SOUTHEAST FROM SOUTHERN ALBERTA
INTO EASTERN MONTANA. CURRENT PRECIPITATION ORIENTATED ALONG THE
SURFACE LOW`S WARM FRONT...FROM NORTH OF GLASGOW MT SOUTHEAST
INTO FAR SOUTHWESTERN NORTH DAKOTA. AREA OF LOW STRATUS AND FOG
ACROSS THE JAMES RIVER VALLEY CONTINUES TO SPREAD SLOWLY NORTH AND
WEST THANKS TO A MOIST SOUTHEASTERLY LOW LEVEL FLOW AHEAD OF THE
SFC LOW.
COMPLEX FORECAST OVER THE NEXT 24-36 HOURS. AS THE
HRRR...NAM...AND RAP ALL INDICATE...STRATUS AND FOG NOW OVER THE
JAMES VALLEY WILL CONTINUE TO EXPAND WEST AND NORTH ACROSS THE
JAMES RIVER VALLEY INTO CENTRAL NORTH DAKOTA TONIGHT. WILL NEED
TO MONITOR VISIBILITIES IN CASE A DENSE FOG ADVISORY IS NEEDED FOR
THE JAMES VALLEY OR OTHER AREAS THIS EVENING. ALSO...MODELS
HINTING RATHER STRONGLY AT LIGHT PRECIPITATION OVER MY EAST. WITH
DRY AIR ALOFT OPTED TO MAINTAIN A MENTION OF FREEZING DRIZZLE WITH
THE STRATUS AND FOG UNTIL WE BECOME SATURATED OVERNIGHT.
POPS ON TRACK WITH INCREASING CHANCES FOR PRECIPITATION IN THE
FORM OF RAIN SOUTHWEST AND A MIX NORTHWEST THIS AFTERNOON AND
EVENING...EVENTUALLY CHANGING TO ALL SNOW BY LATE EVENING. SNOW
CONTINUES ACROSS THE WEST AND EVEN REDEVELOPS ON MONDAY AS A
DEFORMATION ZONE AND ANOTHER MID LEVEL IMPULSE IMPACT THE AREA.
WITH CAA SNOW RATIOS WILL SUPPORT ACCUMULATING SNOWFALL OF 1 TO
NEAR 4 INCHES ACROSS THE SOUTHWEST. COMBINED WITH 15-25KTS OF WIND
ON THE BACKSIDE OF THE SFC LOW...OPTED TO HOIST A WINTER WEATHER
ADVISORY STARTING 06Z TONIGHT THROUGH 12Z TUESDAY.
ACROSS THE SOUTHEAST ON MONDAY...THE STORM SYSTEM PUSHING
SOUTHEAST TONIGHT WILL BE OVER WESTERN IOWA MONDAY...WRAPPING A
TROWAL BACK NORTHWEST AND THEN SOUTHWARD THROUGH THE EASTERN
DAKOTAS...INCLUDING THE JAMES RIVER VALLEY. TWO TO FOUR INCHES
WILL BE POSSIBLE THERE. WILL CONTINUE WITH THE SPS FOR THIS AREA
FOR NOW AND LET THE MID CREW DIGEST NEWER MODEL DATA. STILL SOME
UNCERTAINTY WITH QPF AND PLACEMENTS WITH MODELS NOT 100 PERCENT IN
AGREEMENT JUST YET.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 312 PM CST SUN DEC 21 2014
WINTER WEATHER MONDAY INTO TUESDAY...IMPACTING EARLY CHRISTMAS
TRAVEL FOR MUCH OF NORTH DAKOTA.
THE CURRENT MODEL SUITE PROVIDES GOOD AGREEMENT ON A STRONG LOW
PRESSURE SYSTEM BOTTOMING OUT OVER THE CENTRAL NORTHERN
PLAINS...KEEPING MUCH OF THE PRECIPITATION TO THE SOUTH AND EAST OF
NORTH DAKOTA. GOOD MODEL CONSENSUS ON TRACKING... THE SYSTEM IS
PROJECTED TO SLIDE SOUTH OVER NEBRASKA...THEN BEGIN TO TRACK
NORTHEASTWARD BY MONDAY NIGHT. AS THE SYSTEM TRACKS
NORTHEAST...BETWEEN TWO AND THREE INCHES OF SNOW IS FORECAST FOR
EASTERN AND SOUTHERN PORTIONS OF NORTH DAKOTA. OTHER AREAS COULD
RECEIVE UP TO AN INCH. BREEZY NORTHWESTERLY WINDS ARE ALSO FORECAST
ACROSS MUCH OF THE STATE...CREATING THE POTENTIAL FOR REDUCED
VISIBILITIES AND HAZARDOUS TRAVEL CONDITIONS.
SEASONAL TEMPERATURES ARE EXPECTED THROUGH MUCH OF THE EXTENDED.
THOUGH...ARCTIC LOW PRESSURE IS PROJECTED TO BEGIN SAGGING SOUTHWARD
FRIDAY...PRODUCING BELOW AVERAGE TEMPERATURES FRIDAY INTO SUNDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 928 PM CST SUN DEC 21 2014
HAZARDS TO AVIATION TONIGHT INVOLVE LOW IFR CONDITIONS WITH
FREEZING DRIZZLE CENTRAL AND EAST AND RAIN CHANGING TO SNOW WITH
A WINTRY MIX OF FREEZING RAIN AND SLEET AFTER MIDNIGHT WEST.
WIDESPREAD IFR CONDITIONS WILL PREVAIL STATEWIDE. SNOW AND
BLOWING SNOW SOUTHWEST WILL IMPACT KDIK WITH GUSTS TO 35 KTS AND
VSBYS 1 MILE IN SNOW AND BLOWING SNOW MONDAY AFTERNOON.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 AM CST /5 AM MST/ TUESDAY FOR
NDZ017-031>033-040-041-043-044.
&&
$$
UPDATE...WAA
SHORT TERM...NH
LONG TERM...AC
AVIATION...WAA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
645 PM CST SUN DEC 21 2014
.UPDATE...
ISSUED AT 637 PM CST SUN DEC 21 2014
COMPLEX WINTER WEATHER PATTERN BEGINNING AS RAIN ACROSS THE WEST
THIS EVENING.LOW STRATUS AND FOG CONTINUE ACROSS THE CENTRAL AND
EAST. THE POTENTIAL FOR FREEZING DRIZZLE REMAINS THERE. BASED ON
CURRENT TRENDS THE FORECAST IS OK SO FAR. WINTER WEATHER ADVISORY
BEGINS AT 06Z/11PM MST SOUTHWEST THIS EVENING.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 312 PM CST SUN DEC 21 2014
FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE
PLENTIFUL...RAIN CHANGING TO SNOW WEST THIS EVENING WITH
ACCUMULATIONS AND INCREASING WIND INTO MONDAY...AREAS OF FOG AND
PATCHY FREEZING DRIZZLE EAST...AND MORE ACCUMULATING SNOW
SOUTHEAST DEVELOPING MONDAY MORNING AND AFTERNOON.
CURRENTLY...INCOMING STORM SYSTEM ON THE NOSE OF A POWERFUL 150KT
+ UPPER LEVEL JET STREAK NOW OVER THE NORTHERN ROCKIES. ASSOCIATED
SURFACE LOW DEVELOPING AND MOVING SOUTHEAST FROM SOUTHERN ALBERTA
INTO EASTERN MONTANA. CURRENT PRECIPITATION ORIENTATED ALONG THE
SURFACE LOW`S WARM FRONT...FROM NORTH OF GLASGOW MT SOUTHEAST
INTO FAR SOUTHWESTERN NORTH DAKOTA. AREA OF LOW STRATUS AND FOG
ACROSS THE JAMES RIVER VALLEY CONTINUES TO SPREAD SLOWLY NORTH AND
WEST THANKS TO A MOIST SOUTHEASTERLY LOW LEVEL FLOW AHEAD OF THE
SFC LOW.
COMPLEX FORECAST OVER THE NEXT 24-36 HOURS. AS THE
HRRR...NAM...AND RAP ALL INDICATE...STRATUS AND FOG NOW OVER THE
JAMES VALLEY WILL CONTINUE TO EXPAND WEST AND NORTH ACROSS THE
JAMES RIVER VALLEY INTO CENTRAL NORTH DAKOTA TONIGHT. WILL NEED
TO MONITOR VISIBILITIES IN CASE A DENSE FOG ADVISORY IS NEEDED FOR
THE JAMES VALLEY OR OTHER AREAS THIS EVENING. ALSO...MODELS
HINTING RATHER STRONGLY AT LIGHT PRECIPITATION OVER MY EAST. WITH
DRY AIR ALOFT OPTED TO MAINTAIN A MENTION OF FREEZING DRIZZLE WITH
THE STRATUS AND FOG UNTIL WE BECOME SATURATED OVERNIGHT.
POPS ON TRACK WITH INCREASING CHANCES FOR PRECIPITATION IN THE
FORM OF RAIN SOUTHWEST AND A MIX NORTHWEST THIS AFTERNOON AND
EVENING...EVENTUALLY CHANGING TO ALL SNOW BY LATE EVENING. SNOW
CONTINUES ACROSS THE WEST AND EVEN REDEVELOPS ON MONDAY AS A
DEFORMATION ZONE AND ANOTHER MID LEVEL IMPULSE IMPACT THE AREA.
WITH CAA SNOW RATIOS WILL SUPPORT ACCUMULATING SNOWFALL OF 1 TO
NEAR 4 INCHES ACROSS THE SOUTHWEST. COMBINED WITH 15-25KTS OF WIND
ON THE BACKSIDE OF THE SFC LOW...OPTED TO HOIST A WINTER WEATHER
ADVISORY STARTING 06Z TONIGHT THROUGH 12Z TUESDAY.
ACROSS THE SOUTHEAST ON MONDAY...THE STORM SYSTEM PUSHING
SOUTHEAST TONIGHT WILL BE OVER WESTERN IOWA MONDAY...WRAPPING A
TROWAL BACK NORTHWEST AND THEN SOUTHWARD THROUGH THE EASTERN
DAKOTAS...INCLUDING THE JAMES RIVER VALLEY. TWO TO FOUR INCHES
WILL BE POSSIBLE THERE. WILL CONTINUE WITH THE SPS FOR THIS AREA
FOR NOW AND LET THE MID CREW DIGEST NEWER MODEL DATA. STILL SOME
UNCERTAINTY WITH QPF AND PLACEMENTS WITH MODELS NOT 100 PERCENT IN
AGREEMENT JUST YET.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 312 PM CST SUN DEC 21 2014
WINTER WEATHER MONDAY INTO TUESDAY...IMPACTING EARLY CHRISTMAS
TRAVEL FOR MUCH OF NORTH DAKOTA.
THE CURRENT MODEL SUITE PROVIDES GOOD AGREEMENT ON A STRONG LOW
PRESSURE SYSTEM BOTTOMING OUT OVER THE CENTRAL NORTHERN
PLAINS...KEEPING MUCH OF THE PRECIPITATION TO THE SOUTH AND EAST OF
NORTH DAKOTA. GOOD MODEL CONSENSUS ON TRACKING... THE SYSTEM IS
PROJECTED TO SLIDE SOUTH OVER NEBRASKA...THEN BEGIN TO TRACK
NORTHEASTWARD BY MONDAY NIGHT. AS THE SYSTEM TRACKS
NORTHEAST...BETWEEN TWO AND THREE INCHES OF SNOW IS FORECAST FOR
EASTERN AND SOUTHERN PORTIONS OF NORTH DAKOTA. OTHER AREAS COULD
RECEIVE UP TO AN INCH. BREEZY NORTHWESTERLY WINDS ARE ALSO FORECAST
ACROSS MUCH OF THE STATE...CREATING THE POTENTIAL FOR REDUCED
VISIBILITIES AND HAZARDOUS TRAVEL CONDITIONS.
SEASONAL TEMPERATURES ARE EXPECTED THROUGH MUCH OF THE EXTENDED.
THOUGH...ARCTIC LOW PRESSURE IS PROJECTED TO BEGIN SAGGING SOUTHWARD
FRIDAY...PRODUCING BELOW AVERAGE TEMPERATURES FRIDAY INTO SUNDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 637 PM CST SUN DEC 21 2014
HAZARDS TO AVIATION TONIGHT INVOLVE LOW IFR CONDITIONS WITH
FREEZING DRIZZLE CENTRAL AND EAST AND RAIN CHANGING TO SNOW WITH
A WINTRY MIX OF FREEZING RAIN AND SLEET THIS EVENING WEST. THEN
AFTER 06Z/MIDNIGHT CST TONIGHT WINGSPREAD IFR CONDITIONS WILL
PREVAIL STATEWIDE. SNOW AND BLOWING SNOW SOUTHWEST WILL IMPACT
KDIK WITH GUSTS TO 35 KTS AND VSBYS 1 MILE IN SNOW AND BLOWING
SNOW MONDAY AFTERNOON.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM MIDNIGHT CST /11 PM MST/ TONIGHT TO
6 AM CST /5 AM MST/ TUESDAY FOR NDZ017-031>033-040-041-043-044.
&&
$$
UPDATE...WAA
SHORT TERM...NH
LONG TERM...AC
AVIATION...WAA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
201 PM CST SAT DEC 20 2014
.UPDATE...
ISSUED AT 201 PM CST SAT DEC 20 2014
QUICK UPDATE TO CANCEL THE DENSE FOG ADVISORY. MID LEVEL CLOUDS
AND A SOUTHWEST WIND HAVE LIFTED MOST AREAS OF FOG...WITH THE FAR
NORTHEAST EXPECTED TO IMPROVE OVER THE NEXT HOUR.
UPDATE
ISSUED AT 1239 PM CST SAT DEC 20 2014
TRIMMED OFF A FEW MORE COUNTIES FROM THE DENSE FOG ADVISORY AS THE
BAND OF MID LEVEL CLOUDS AND A TRANSITION TO A SOUTHWEST WIND SCOURS
OUT THE LOW LEVEL MOISTURE. WILL MAINTAIN MY EASTERN COUNTIES
THROUGH 20Z AND MONITOR IN CASE ANOTHER EXTENSION BECOMES NEEDED.
DO NOT ANTICIPATE DENSE FOG FOR TONIGHT. DID HAVE SOME VERY LIGHT
ZR HERE IN BISMARCK LESS THAN AN HOUR AGO...SO WILL MAINTAIN A
SLIGHT CHANCE POP WITH THE BAND OF RADAR RETURNS ORIENTATED ALONG
A NORTH TO SOUTH-SOUTHEAST FRONTAL BOUNDARY.
UPDATE
ISSUED AT 1044 AM CST SAT DEC 20 2014
REMOVED KIDDER COUNTY FROM THE DENSE FOG ADVISORY. REMAINDER OF
THE FORECAST REMAINS UNCHANGED.
UPDATE
ISSUED AT 1008 AM CST SAT DEC 20 2014
WILL EXTEND THE DENSE FOG ADVISORY FOR MY NORTH CENTRAL AND EAST
THROUGH 20Z. SEE NO SIGNS OF VISIBILITIES IMPROVING UNTIL THE MID
LEVEL CLOUD DECK PUSHES FARTHER EAST NOW THROUGH 20Z ALONG A
FRONTAL BOUNDARY. UNSURE IF ANYTHING IS REACHING THE GROUND WITH A
BAND OF THE RADAR ECHOS STRETCHING FROM CROSBY SOUTH-SOUTHEAST
THROUGH GRANT COUNTY. CALLED SEVERAL LOCATIONS AND THUS FAR NO
REPORTS. STILL WORTH A MENTION SINCE PRECIP TYPE WILL BE ZR/SLEET
UNTIL SURFACE TEMPERATURES WARM.
ALREADY CLEARING OVER MY WEST AND EXPECT THIS TREND TO CONTINUE
SOUTHWEST INTO SOUTH CENTRAL AS THE DAY PROGRESSES. CLOUDS
REDEVELOP NORTHWEST AS WRAP AROUND MOISTURE PIVOTS IN FROM
NORTHEASTERN MONTANA. MODIFIED SKY GRIDS FOR THIS...AND ALSO
TRENDED POPS DOWN LATER TODAY INTO TONIGHT.
UPDATE ISSUED AT 616 AM CST SAT DEC 20 2014
MID LEVEL CLOUD COVER ACROSS WESTERN NORTH DAKOTA HAS LEAD TO THE
SEEDING OF THE LOW LEVEL STRATUS ACROSS THE FAR NORTHWEST. THE
RESULT IS LIGHT FLURRIES AND GREATLY IMPROVED VISIBILITIES FROM
THE PREVIOUS DENSE FOG. THUS...LET THE DENSE FOG ADVISORY EXPIRE
ON TIME FOR DIVIDE AND WILLIAMS COUNTIES. ELSEWHERE...GIVEN
OBSERVED TRENDS AND THE 11 UTC HRRR VISIBILITY FORECAST...EXTENDED
THE REMAINDER OF THE ADVISORY THROUGH 16 UTC AND ADDED LAMOURE AND
DICKEY COUNTIES. GIVEN THE TRENDS IN THE HRRR...PORTIONS OF THE
ADVISORY ACROSS THE JAMES RIVER VALLEY MAY NEED TO BE EXTENDED
INTO THE AFTERNOON.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 352 AM CST SAT DEC 20 2014
MAIN CONCERNS IN THE SHORT TERM ARE THE PERSISTENT FOG IN THE NORTH
AND CENTRAL TODAY...AND PRECIPITATION CHANCES AND WEATHER TYPE FOR
TODAY AND TONIGHT.
CURRENTLY...WATER VAPOR SATELLITE LOOP INDICATES THE NEXT UPPER
LEVEL SHORTWAVE TO AFFECT THE STATE TODAY WAS OVER NORTH CENTRAL
MONTANA/SOUTHERN SASKATCHEWAN/ALBERTA. AT THE SURFACE...LOW PRESSURE
WAS CENTERED OVER THE SOUTHERN BORDER OF ALBERTA/SASKATCHEWAN WITH A
TROUGH EXTENDING SOUTHEAST ACROSS EASTERN MONTANA. WIDESPREAD FOG
WITH VISIBILITIES RANGING FROM 1/4 MILE TO 1 MILE EXTENDED ACROSS
NORTHWESTERN AND MUCH OF CENTRAL NORTH DAKOTA.
TODAY THE UPPER LEVEL LOW/TROUGH IS PROGGED TO ENTER WESTERN NORTH
DAKOTA THIS MORNING AND ENTER CENTRAL NORTH DAKOTA THIS
AFTERNOON...EXITING NORTH DAKOTA SUNDAY MORNING. AT THE
SURFACE...THE SURFACE LOW AND ATTENDANT WARM FRONT IS FORECAST TO
MOVE EAST TODAY. THE LOW SHOULD MOVE EAST ACROSS SOUTHERN
SASKATCHEWAN/MANITOBA...WITH THE WARM FRONT ENTERING WESTERN NORTH
DAKOTA THIS MORNING...AND CENTRAL NORTH DAKOTA THIS AFTERNOON.
REGARDING THE FOG...AS THE AFOREMENTIONED SYSTEM MOVES INTO WESTERN
NORTH DAKOTA VISIBILITIES SHOULD IMPROVE WITH SUFFICIENT LOW TO MID
LEVEL MIXING. THE HRRR VISIBILITY PROGS SUPPORT THIS AS WELL. AREAS
OF FOG SHOULD PERSIST IN CENTRAL NORTH DAKOTA INTO THE
AFTERNOON...IMPROVING VISIBILITIES WITH TIME FROM WEST TO EAST AS THE
LOW PRESSURE SYSTEM ADVANCES EASTWARD.
THE SHORTWAVE AND SURFACE WARM FRONT WILL ALSO BRING LIGHT SCATTERED
PRECIPITATION TODAY AND TONIGHT. LOOKING AT INCREASING CHANCES THIS
MORNING IN THE WEST...EXPANDING INTO CENTRAL NORTH DAKOTA THIS
AFTERNOON. WARM ADVECTION ALOFT WILL RESULT IN MIXED PRECIPITATION
OF FREEZING DRIZZLE OR DRIZZLE EARLY THIS MORNING WITH CHANCES OF
LIGHT RAIN/DRIZZLE THIS AFTERNOON IN THE WEST AS TEMPERATURES RISE
INTO THE 30S. FARTHER EAST FREEZING DRIZZLE OR LIGHT SNOW SHOULD BE
THE PREDOMINANT WEATHER TYPE.
TONIGHT THE MAIN ENERGY FROM THE UPPER LEVEL TROUGH SHOULD KEEP THE
CHANCE OF PRECIPITATION CONFINED TO THE NORTH CENTRAL AND JAMES
RIVER VALLEY AND EASTWARD. FREEZING DRIZZLE OR LIGHT SNOW WOULD BE
THE MAIN WEATHER TYPE THERE TONIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 330 AM CST SAT DEC 20 2014
A WINTRY MIX POSSIBLE SUNDAY EVENING INTO MONDAY NIGHT...FOLLOWED
BY SNOWFALL POTENTIAL EARLY NEXT WEEK IMPACTING CHRISTMAS TRAVEL
HIGHLIGHT THE EXTENDED FORECAST.
FOR THE 00 UTC GUIDANCE SUITE...WHILE IN AGREEMENT ON GENERAL
FEATURES THROUGH THE EXTENDED FORECAST...SPATIAL DIFFERENCES IN
THE MASS FIELDS AND TIMING RESULT IN NON-TRIVIAL IMPACTS TO
SENSIBLE WEATHER THROUGH THE PERIOD. OVERALL...WEIGHED HEAVILY ON
THE 00 UTC ECMWF AND 03 UTC SREF WHICH RESIDE IN THE MIDDLE OF THE
ENVELOPE OF SOLUTIONS. FOR SUNDAY...A LEAD SHORTWAVE EJECTING OUT
OF THE ROCKIES IS FORECAST TO RESULT IN A RAIN AND SNOW MIX
DEPENDING ON SURFACE TEMPERATURES ACROSS WESTERN NORTH DAKOTA IN
THE AFTERNOON.
THE CHALLENGE IS SUNDAY EVENING INTO MONDAY NIGHT IN REGARDS TO
PRECIPITATION TYPE ACROSS CENTRAL NORTH DAKOTA. A MELTING LAYER
ALOFT ABOVE SUB-FREEZING SURFACE TEMPERATURES IS FORECAST TO
EXIST. HOWEVER...DRY AIR IN THE 900-750 MB LAYER WILL HAVE TO BE
SATURATED FOR PRECIPITATION TO REACH THE GROUND. THUS ENTERS THE
UNCERTAINTY AS TO HOW MUCH OF THE MELTING LAYER WILL REMAIN POST-
SATURATION DUE TO THE WET-BULB EFFECT. THERE APPEARS TO BE A BRIEF
WINDOW...ESPECIALLY ACROSS SOUTH CENTRAL NORTH DAKOTA...FOR THE
WARM LAYER TO BE AROUND +2 TO +2.5 C AROUND 00-03 UTC FOR A WINTRY
MIX OF FREEZING RAIN...SLEET AND MELTED SNOW TO BE POSSIBLE.
OVERALL AMOUNTS WILL BE LIGHT WITH THE COLUMN QUICKLY COOLING TO
SUPPORT ALL SNOW BETWEEN 03-06 UTC. THEREAFTER...ATTENTION TURNS
TO CYCLOGENESIS ACROSS THE EASTERN DAKOTAS AND INTO THE UPPER
MISSISSIPPI VALLEY MONDAY. THE 00 UTC DETERMINISTIC AND ENSEMBLE
SOLUTIONS SHOW A VARIED UPPER LEVEL LOW POSITION FROM NORTH
DAKOTA ON THE NAM TO IOWA ON THE GFS...WITH THE SREF AND ECMWF IN
BETWEEN. THUS...WIDESPREAD LIGHT SNOW IS EXPECTED FOR THE AREA
MONDAY ON ALL SOLUTIONS...WITH HIGHER AMOUNTS IN BANDING POSSIBLE.
HOWEVER...UNCERTAINTY IN THESE BANDS IS RATHER HIGH UNTIL THE MASS
FIELDS COME INTO BETTER AGREEMENT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1239 PM CST SAT DEC 20 2014
LIFR CEILINGS/VISIBILITIES CONTINUE AT KJMS. KMOT HAS IMPROVED
FROM IFR TO NOW VFR. FARTHER WEST KBIS-KISN AND KDIK SHOULD
REMAIN VFR. STRATUS AND FOG SHOULD ERODE EAST AS AN APPROACHING
SYSTEM BRINGS A DRIER SOUTHWEST FLOW. KJMS NOT IMPROVING UNTIL
AROUND MID TO LATE AFTERNOON. THERE IS A RISK OF ISOLATED TO
SCATTERED MIXED PRECIPITATION AT CENTRAL AND EASTERN TAF SITES
THIS AFTERNOON. DID NOT MENTION IN TAFS AS LESS THAN 50 PERCENT
CHANCE AND ONLY TRACE LIQUID EXPECTED.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...NH
SHORT TERM...JV
LONG TERM...AYD
AVIATION...NH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1239 PM CST SAT DEC 20 2014
.UPDATE...
ISSUED AT 1239 PM CST SAT DEC 20 2014
TRIMMED OFF A FEW MORE COUNTIES FROM THE DENSE FOG ADVISORY AS THE
BAND OF MID LEVEL CLOUDS AND A TRANSITION TO A SOUTHWEST WIND SCOURS
OUT THE LOW LEVEL MOISTURE. WILL MAINTAIN MY EASTERN COUNTIES
THROUGH 20Z AND MONITOR IN CASE ANOTHER EXTENSION BECOMES NEEDED.
DO NOT ANTICIPATE DENSE FOG FOR TONIGHT. DID HAVE SOME VERY LIGHT
ZR HERE IN BISMARCK LESS THAN AN HOUR AGO...SO WILL MAINTAIN A
SLIGHT CHANCE POP WITH THE BAND OF RADAR RETURNS ORIENTATED ALONG
A NORTH TO SOUTH-SOUTHEAST FRONTAL BOUNDARY.
UPDATE
ISSUED AT 1044 AM CST SAT DEC 20 2014
REMOVED KIDDER COUNTY FROM THE DENSE FOG ADVISORY. REMAINDER OF
THE FORECAST REMAINS UNCHANGED.
UPDATE
ISSUED AT 1008 AM CST SAT DEC 20 2014
WILL EXTEND THE DENSE FOG ADVISORY FOR MY NORTH CENTRAL AND EAST
THROUGH 20Z. SEE NO SIGNS OF VISIBILITIES IMPROVING UNTIL THE MID
LEVEL CLOUD DECK PUSHES FARTHER EAST NOW THROUGH 20Z ALONG A
FRONTAL BOUNDARY. UNSURE IF ANYTHING IS REACHING THE GROUND WITH A
BAND OF THE RADAR ECHOS STRETCHING FROM CROSBY SOUTH-SOUTHEAST
THROUGH GRANT COUNTY. CALLED SEVERAL LOCATIONS AND THUS FAR NO
REPORTS. STILL WORTH A MENTION SINCE PRECIP TYPE WILL BE ZR/SLEET
UNTIL SURFACE TEMPERATURES WARM.
ALREADY CLEARING OVER MY WEST AND EXPECT THIS TREND TO CONTINUE
SOUTHWEST INTO SOUTH CENTRAL AS THE DAY PROGRESSES. CLOUDS
REDEVELOP NORTHWEST AS WRAP AROUND MOISTURE PIVOTS IN FROM
NORTHEASTERN MONTANA. MODIFIED SKY GRIDS FOR THIS...AND ALSO
TRENDED POPS DOWN LATER TODAY INTO TONIGHT.
UPDATE ISSUED AT 616 AM CST SAT DEC 20 2014
MID LEVEL CLOUD COVER ACROSS WESTERN NORTH DAKOTA HAS LEAD TO THE
SEEDING OF THE LOW LEVEL STRATUS ACROSS THE FAR NORTHWEST. THE
RESULT IS LIGHT FLURRIES AND GREATLY IMPROVED VISIBILITIES FROM
THE PREVIOUS DENSE FOG. THUS...LET THE DENSE FOG ADVISORY EXPIRE
ON TIME FOR DIVIDE AND WILLIAMS COUNTIES. ELSEWHERE...GIVEN
OBSERVED TRENDS AND THE 11 UTC HRRR VISIBILITY FORECAST...EXTENDED
THE REMAINDER OF THE ADVISORY THROUGH 16 UTC AND ADDED LAMOURE AND
DICKEY COUNTIES. GIVEN THE TRENDS IN THE HRRR...PORTIONS OF THE
ADVISORY ACROSS THE JAMES RIVER VALLEY MAY NEED TO BE EXTENDED
INTO THE AFTERNOON.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 352 AM CST SAT DEC 20 2014
MAIN CONCERNS IN THE SHORT TERM ARE THE PERSISTENT FOG IN THE NORTH
AND CENTRAL TODAY...AND PRECIPITATION CHANCES AND WEATHER TYPE FOR
TODAY AND TONIGHT.
CURRENTLY...WATER VAPOR SATELLITE LOOP INDICATES THE NEXT UPPER
LEVEL SHORTWAVE TO AFFECT THE STATE TODAY WAS OVER NORTH CENTRAL
MONTANA/SOUTHERN SASKATCHEWAN/ALBERTA. AT THE SURFACE...LOW PRESSURE
WAS CENTERED OVER THE SOUTHERN BORDER OF ALBERTA/SASKATCHEWAN WITH A
TROUGH EXTENDING SOUTHEAST ACROSS EASTERN MONTANA. WIDESPREAD FOG
WITH VISIBILITIES RANGING FROM 1/4 MILE TO 1 MILE EXTENDED ACROSS
NORTHWESTERN AND MUCH OF CENTRAL NORTH DAKOTA.
TODAY THE UPPER LEVEL LOW/TROUGH IS PROGGED TO ENTER WESTERN NORTH
DAKOTA THIS MORNING AND ENTER CENTRAL NORTH DAKOTA THIS
AFTERNOON...EXITING NORTH DAKOTA SUNDAY MORNING. AT THE
SURFACE...THE SURFACE LOW AND ATTENDANT WARM FRONT IS FORECAST TO
MOVE EAST TODAY. THE LOW SHOULD MOVE EAST ACROSS SOUTHERN
SASKATCHEWAN/MANITOBA...WITH THE WARM FRONT ENTERING WESTERN NORTH
DAKOTA THIS MORNING...AND CENTRAL NORTH DAKOTA THIS AFTERNOON.
REGARDING THE FOG...AS THE AFOREMENTIONED SYSTEM MOVES INTO WESTERN
NORTH DAKOTA VISIBILITIES SHOULD IMPROVE WITH SUFFICIENT LOW TO MID
LEVEL MIXING. THE HRRR VISIBILITY PROGS SUPPORT THIS AS WELL. AREAS
OF FOG SHOULD PERSIST IN CENTRAL NORTH DAKOTA INTO THE
AFTERNOON...IMPROVING VISIBILITIES WITH TIME FROM WEST TO EAST AS THE
LOW PRESSURE SYSTEM ADVANCES EASTWARD.
THE SHORTWAVE AND SURFACE WARM FRONT WILL ALSO BRING LIGHT SCATTERED
PRECIPITATION TODAY AND TONIGHT. LOOKING AT INCREASING CHANCES THIS
MORNING IN THE WEST...EXPANDING INTO CENTRAL NORTH DAKOTA THIS
AFTERNOON. WARM ADVECTION ALOFT WILL RESULT IN MIXED PRECIPITATION
OF FREEZING DRIZZLE OR DRIZZLE EARLY THIS MORNING WITH CHANCES OF
LIGHT RAIN/DRIZZLE THIS AFTERNOON IN THE WEST AS TEMPERATURES RISE
INTO THE 30S. FARTHER EAST FREEZING DRIZZLE OR LIGHT SNOW SHOULD BE
THE PREDOMINANT WEATHER TYPE.
TONIGHT THE MAIN ENERGY FROM THE UPPER LEVEL TROUGH SHOULD KEEP THE
CHANCE OF PRECIPITATION CONFINED TO THE NORTH CENTRAL AND JAMES
RIVER VALLEY AND EASTWARD. FREEZING DRIZZLE OR LIGHT SNOW WOULD BE
THE MAIN WEATHER TYPE THERE TONIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 330 AM CST SAT DEC 20 2014
A WINTRY MIX POSSIBLE SUNDAY EVENING INTO MONDAY NIGHT...FOLLOWED
BY SNOWFALL POTENTIAL EARLY NEXT WEEK IMPACTING CHRISTMAS TRAVEL
HIGHLIGHT THE EXTENDED FORECAST.
FOR THE 00 UTC GUIDANCE SUITE...WHILE IN AGREEMENT ON GENERAL
FEATURES THROUGH THE EXTENDED FORECAST...SPATIAL DIFFERENCES IN
THE MASS FIELDS AND TIMING RESULT IN NON-TRIVIAL IMPACTS TO
SENSIBLE WEATHER THROUGH THE PERIOD. OVERALL...WEIGHED HEAVILY ON
THE 00 UTC ECMWF AND 03 UTC SREF WHICH RESIDE IN THE MIDDLE OF THE
ENVELOPE OF SOLUTIONS. FOR SUNDAY...A LEAD SHORTWAVE EJECTING OUT
OF THE ROCKIES IS FORECAST TO RESULT IN A RAIN AND SNOW MIX
DEPENDING ON SURFACE TEMPERATURES ACROSS WESTERN NORTH DAKOTA IN
THE AFTERNOON.
THE CHALLENGE IS SUNDAY EVENING INTO MONDAY NIGHT IN REGARDS TO
PRECIPITATION TYPE ACROSS CENTRAL NORTH DAKOTA. A MELTING LAYER
ALOFT ABOVE SUB-FREEZING SURFACE TEMPERATURES IS FORECAST TO
EXIST. HOWEVER...DRY AIR IN THE 900-750 MB LAYER WILL HAVE TO BE
SATURATED FOR PRECIPITATION TO REACH THE GROUND. THUS ENTERS THE
UNCERTAINTY AS TO HOW MUCH OF THE MELTING LAYER WILL REMAIN POST-
SATURATION DUE TO THE WET-BULB EFFECT. THERE APPEARS TO BE A BRIEF
WINDOW...ESPECIALLY ACROSS SOUTH CENTRAL NORTH DAKOTA...FOR THE
WARM LAYER TO BE AROUND +2 TO +2.5 C AROUND 00-03 UTC FOR A WINTRY
MIX OF FREEZING RAIN...SLEET AND MELTED SNOW TO BE POSSIBLE.
OVERALL AMOUNTS WILL BE LIGHT WITH THE COLUMN QUICKLY COOLING TO
SUPPORT ALL SNOW BETWEEN 03-06 UTC. THEREAFTER...ATTENTION TURNS
TO CYCLOGENESIS ACROSS THE EASTERN DAKOTAS AND INTO THE UPPER
MISSISSIPPI VALLEY MONDAY. THE 00 UTC DETERMINISTIC AND ENSEMBLE
SOLUTIONS SHOW A VARIED UPPER LEVEL LOW POSITION FROM NORTH
DAKOTA ON THE NAM TO IOWA ON THE GFS...WITH THE SREF AND ECMWF IN
BETWEEN. THUS...WIDESPREAD LIGHT SNOW IS EXPECTED FOR THE AREA
MONDAY ON ALL SOLUTIONS...WITH HIGHER AMOUNTS IN BANDING POSSIBLE.
HOWEVER...UNCERTAINTY IN THESE BANDS IS RATHER HIGH UNTIL THE MASS
FIELDS COME INTO BETTER AGREEMENT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1239 PM CST SAT DEC 20 2014
LIFR CEILINGS/VISIBILITIES CONTINUE AT KJMS. KMOT HAS IMPROVED
FROM IFR TO NOW VFR. FARTHER WEST KBIS-KISN AND KDIK SHOULD
REMAIN VFR. STRATUS AND FOG SHOULD ERODE EAST AS AN APPROACHING
SYSTEM BRINGS A DRIER SOUTHWEST FLOW. KJMS NOT IMPROVING UNTIL
AROUND MID TO LATE AFTERNOON. THERE IS A RISK OF ISOLATED TO
SCATTERED MIXED PRECIPITATION AT CENTRAL AND EASTERN TAF SITES
THIS AFTERNOON. DID NOT MENTION IN TAFS AS LESS THAN 50 PERCENT
CHANCE AND ONLY TRACE LIQUID EXPECTED.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 2 PM CST THIS AFTERNOON FOR NDZ004-005-
012-013-023-025-037-048-051.
&&
$$
UPDATE...NH
SHORT TERM...JV
LONG TERM...AYD
AVIATION...NH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1044 AM CST SAT DEC 20 2014
.UPDATE...
ISSUED AT 1044 AM CST SAT DEC 20 2014
REMOVED KIDDER COUNTY FROM THE DENSE FOG ADVISORY. REMAINDER OF
THE FORECAST REMAINS UNCHANGED.
UPDATE
ISSUED AT 1008 AM CST SAT DEC 20 2014
WILL EXTEND THE DENSE FOG ADVISORY FOR MY NORTH CENTRAL AND EAST
THROUGH 20Z. SEE NO SIGNS OF VISIBILITIES IMPROVING UNTIL THE MID
LEVEL CLOUD DECK PUSHES FARTHER EAST NOW THROUGH 20Z ALONG A
FRONTAL BOUNDARY. UNSURE IF ANYTHING IS REACHING THE GROUND WITH A
BAND OF THE RADAR ECHOS STRETCHING FROM CROSBY SOUTH-SOUTHEAST
THROUGH GRANT COUNTY. CALLED SEVERAL LOCATIONS AND THUS FAR NO
REPORTS. STILL WORTH A MENTION SINCE PRECIP TYPE WILL BE ZR/SLEET
UNTIL SURFACE TEMPERATURES WARM.
ALREADY CLEARING OVER MY WEST AND EXPECT THIS TREND TO CONTINUE
SOUTHWEST INTO SOUTH CENTRAL AS THE DAY PROGRESSES. CLOUDS
REDEVELOP NORTHWEST AS WRAP AROUND MOISTURE PIVOTS IN FROM
NORTHEASTERN MONTANA. MODIFIED SKY GRIDS FOR THIS...AND ALSO
TRENDED POPS DOWN LATER TODAY INTO TONIGHT.
UPDATE ISSUED AT 616 AM CST SAT DEC 20 2014
MID LEVEL CLOUD COVER ACROSS WESTERN NORTH DAKOTA HAS LEAD TO THE
SEEDING OF THE LOW LEVEL STRATUS ACROSS THE FAR NORTHWEST. THE
RESULT IS LIGHT FLURRIES AND GREATLY IMPROVED VISIBILITIES FROM
THE PREVIOUS DENSE FOG. THUS...LET THE DENSE FOG ADVISORY EXPIRE
ON TIME FOR DIVIDE AND WILLIAMS COUNTIES. ELSEWHERE...GIVEN
OBSERVED TRENDS AND THE 11 UTC HRRR VISIBILITY FORECAST...EXTENDED
THE REMAINDER OF THE ADVISORY THROUGH 16 UTC AND ADDED LAMOURE AND
DICKEY COUNTIES. GIVEN THE TRENDS IN THE HRRR...PORTIONS OF THE
ADVISORY ACROSS THE JAMES RIVER VALLEY MAY NEED TO BE EXTENDED
INTO THE AFTERNOON.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 352 AM CST SAT DEC 20 2014
MAIN CONCERNS IN THE SHORT TERM ARE THE PERSISTENT FOG IN THE NORTH
AND CENTRAL TODAY...AND PRECIPITATION CHANCES AND WEATHER TYPE FOR
TODAY AND TONIGHT.
CURRENTLY...WATER VAPOR SATELLITE LOOP INDICATES THE NEXT UPPER
LEVEL SHORTWAVE TO AFFECT THE STATE TODAY WAS OVER NORTH CENTRAL
MONTANA/SOUTHERN SASKATCHEWAN/ALBERTA. AT THE SURFACE...LOW PRESSURE
WAS CENTERED OVER THE SOUTHERN BORDER OF ALBERTA/SASKATCHEWAN WITH A
TROUGH EXTENDING SOUTHEAST ACROSS EASTERN MONTANA. WIDESPREAD FOG
WITH VISIBILITIES RANGING FROM 1/4 MILE TO 1 MILE EXTENDED ACROSS
NORTHWESTERN AND MUCH OF CENTRAL NORTH DAKOTA.
TODAY THE UPPER LEVEL LOW/TROUGH IS PROGGED TO ENTER WESTERN NORTH
DAKOTA THIS MORNING AND ENTER CENTRAL NORTH DAKOTA THIS
AFTERNOON...EXITING NORTH DAKOTA SUNDAY MORNING. AT THE
SURFACE...THE SURFACE LOW AND ATTENDANT WARM FRONT IS FORECAST TO
MOVE EAST TODAY. THE LOW SHOULD MOVE EAST ACROSS SOUTHERN
SASKATCHEWAN/MANITOBA...WITH THE WARM FRONT ENTERING WESTERN NORTH
DAKOTA THIS MORNING...AND CENTRAL NORTH DAKOTA THIS AFTERNOON.
REGARDING THE FOG...AS THE AFOREMENTIONED SYSTEM MOVES INTO WESTERN
NORTH DAKOTA VISIBILITIES SHOULD IMPROVE WITH SUFFICIENT LOW TO MID
LEVEL MIXING. THE HRRR VISIBILITY PROGS SUPPORT THIS AS WELL. AREAS
OF FOG SHOULD PERSIST IN CENTRAL NORTH DAKOTA INTO THE
AFTERNOON...IMPROVING VISIBILITIES WITH TIME FROM WEST TO EAST AS THE
LOW PRESSURE SYSTEM ADVANCES EASTWARD.
THE SHORTWAVE AND SURFACE WARM FRONT WILL ALSO BRING LIGHT SCATTERED
PRECIPITATION TODAY AND TONIGHT. LOOKING AT INCREASING CHANCES THIS
MORNING IN THE WEST...EXPANDING INTO CENTRAL NORTH DAKOTA THIS
AFTERNOON. WARM ADVECTION ALOFT WILL RESULT IN MIXED PRECIPITATION
OF FREEZING DRIZZLE OR DRIZZLE EARLY THIS MORNING WITH CHANCES OF
LIGHT RAIN/DRIZZLE THIS AFTERNOON IN THE WEST AS TEMPERATURES RISE
INTO THE 30S. FARTHER EAST FREEZING DRIZZLE OR LIGHT SNOW SHOULD BE
THE PREDOMINANT WEATHER TYPE.
TONIGHT THE MAIN ENERGY FROM THE UPPER LEVEL TROUGH SHOULD KEEP THE
CHANCE OF PRECIPITATION CONFINED TO THE NORTH CENTRAL AND JAMES
RIVER VALLEY AND EASTWARD. FREEZING DRIZZLE OR LIGHT SNOW WOULD BE
THE MAIN WEATHER TYPE THERE TONIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 330 AM CST SAT DEC 20 2014
A WINTRY MIX POSSIBLE SUNDAY EVENING INTO MONDAY NIGHT...FOLLOWED
BY SNOWFALL POTENTIAL EARLY NEXT WEEK IMPACTING CHRISTMAS TRAVEL
HIGHLIGHT THE EXTENDED FORECAST.
FOR THE 00 UTC GUIDANCE SUITE...WHILE IN AGREEMENT ON GENERAL
FEATURES THROUGH THE EXTENDED FORECAST...SPATIAL DIFFERENCES IN
THE MASS FIELDS AND TIMING RESULT IN NON-TRIVIAL IMPACTS TO
SENSIBLE WEATHER THROUGH THE PERIOD. OVERALL...WEIGHED HEAVILY ON
THE 00 UTC ECMWF AND 03 UTC SREF WHICH RESIDE IN THE MIDDLE OF THE
ENVELOPE OF SOLUTIONS. FOR SUNDAY...A LEAD SHORTWAVE EJECTING OUT
OF THE ROCKIES IS FORECAST TO RESULT IN A RAIN AND SNOW MIX
DEPENDING ON SURFACE TEMPERATURES ACROSS WESTERN NORTH DAKOTA IN
THE AFTERNOON.
THE CHALLENGE IS SUNDAY EVENING INTO MONDAY NIGHT IN REGARDS TO
PRECIPITATION TYPE ACROSS CENTRAL NORTH DAKOTA. A MELTING LAYER
ALOFT ABOVE SUB-FREEZING SURFACE TEMPERATURES IS FORECAST TO
EXIST. HOWEVER...DRY AIR IN THE 900-750 MB LAYER WILL HAVE TO BE
SATURATED FOR PRECIPITATION TO REACH THE GROUND. THUS ENTERS THE
UNCERTAINTY AS TO HOW MUCH OF THE MELTING LAYER WILL REMAIN POST-
SATURATION DUE TO THE WET-BULB EFFECT. THERE APPEARS TO BE A BRIEF
WINDOW...ESPECIALLY ACROSS SOUTH CENTRAL NORTH DAKOTA...FOR THE
WARM LAYER TO BE AROUND +2 TO +2.5 C AROUND 00-03 UTC FOR A WINTRY
MIX OF FREEZING RAIN...SLEET AND MELTED SNOW TO BE POSSIBLE.
OVERALL AMOUNTS WILL BE LIGHT WITH THE COLUMN QUICKLY COOLING TO
SUPPORT ALL SNOW BETWEEN 03-06 UTC. THEREAFTER...ATTENTION TURNS
TO CYCLOGENESIS ACROSS THE EASTERN DAKOTAS AND INTO THE UPPER
MISSISSIPPI VALLEY MONDAY. THE 00 UTC DETERMINISTIC AND ENSEMBLE
SOLUTIONS SHOW A VARIED UPPER LEVEL LOW POSITION FROM NORTH
DAKOTA ON THE NAM TO IOWA ON THE GFS...WITH THE SREF AND ECMWF IN
BETWEEN. THUS...WIDESPREAD LIGHT SNOW IS EXPECTED FOR THE AREA
MONDAY ON ALL SOLUTIONS...WITH HIGHER AMOUNTS IN BANDING POSSIBLE.
HOWEVER...UNCERTAINTY IN THESE BANDS IS RATHER HIGH UNTIL THE MASS
FIELDS COME INTO BETTER AGREEMENT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 1008 AM CST SAT DEC 20 2014
LIFR CEILINGS/VISIBILITIES CONTINUE AT KMOT AND KJMS. KBIS HAS
IMPROVED FROM IFR TO NOW VFR. FARTHER WEST KISN AND KDIK SHOULD
REMAIN VFR. STRATUS AND FOG SHOULD ERODE FROM WEST TO EAST AS AN
APPROACHING SYSTEM BRINGS A DRIER SOUTHWEST FLOW. KMOT SHOULD
BECOME VFR BEFORE/BY 18-19Z. KJMS NOT IMPROVING UNTIL AROUND MID
TO LATE AFTERNOON. THERE IS A RISK OF ISOLATED TO SCATTERED MIXED
PRECIPITATION AT ALL TAF SITES THIS MORNING AND AFTERNOON. DID NOT
MENTION IN TAFS AS LESS THAN 50 PERCENT CHANCE AND ONLY TRACE
LIQUID EXPECTED.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 2 PM CST THIS AFTERNOON FOR NDZ002>005-
011>013-022-023-025-037-048-051.
&&
$$
UPDATE...NH
SHORT TERM...JV
LONG TERM...AYD
AVIATION...JV
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1008 AM CST SAT DEC 20 2014
.UPDATE...
ISSUED AT 1008 AM CST SAT DEC 20 2014
WILL EXTEND THE DENSE FOG ADVISORY FOR MY NORTH CENTRAL AND EAST
THROUGH 20Z. SEE NO SIGNS OF VISIBILITIES IMPROVING UNTIL THE MID
LEVEL CLOUD DECK PUSHES FARTHER EAST NOW THROUGH 20Z ALONG A
FRONTAL BOUNDARY. UNSURE IF ANYTHING IS REACHING THE GROUND WITH A
BAND OF THE RADAR ECHOS STRETCHING FROM CROSBY SOUTH-SOUTHEAST
THROUGH GRANT COUNTY. CALLED SEVERAL LOCATIONS AND THUS FAR NO
REPORTS. STILL WORTH A MENTION SINCE PRECIP TYPE WILL BE ZR/SLEET
UNTIL SURFACE TEMPERATURES WARM.
ALREADY CLEARING OVER MY WEST AND EXPECT THIS TREND TO CONTINUE
SOUTHWEST INTO SOUTH CENTRAL AS THE DAY PROGRESSES. CLOUDS
REDEVELOP NORTHWEST AS WRAP AROUND MOISTURE PIVOTS IN FROM
NORTHEASTERN MONTANA. MODIFIED SKY GRIDS FOR THIS...AND ALSO
TRENDED POPS DOWN LATER TODAY INTO TONIGHT.
UPDATE ISSUED AT 616 AM CST SAT DEC 20 2014
MID LEVEL CLOUD COVER ACROSS WESTERN NORTH DAKOTA HAS LEAD TO THE
SEEDING OF THE LOW LEVEL STRATUS ACROSS THE FAR NORTHWEST. THE
RESULT IS LIGHT FLURRIES AND GREATLY IMPROVED VISIBILITIES FROM
THE PREVIOUS DENSE FOG. THUS...LET THE DENSE FOG ADVISORY EXPIRE
ON TIME FOR DIVIDE AND WILLIAMS COUNTIES. ELSEWHERE...GIVEN
OBSERVED TRENDS AND THE 11 UTC HRRR VISIBILITY FORECAST...EXTENDED
THE REMAINDER OF THE ADVISORY THROUGH 16 UTC AND ADDED LAMOURE AND
DICKEY COUNTIES. GIVEN THE TRENDS IN THE HRRR...PORTIONS OF THE
ADVISORY ACROSS THE JAMES RIVER VALLEY MAY NEED TO BE EXTENDED
INTO THE AFTERNOON.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 352 AM CST SAT DEC 20 2014
MAIN CONCERNS IN THE SHORT TERM ARE THE PERSISTENT FOG IN THE NORTH
AND CENTRAL TODAY...AND PRECIPITATION CHANCES AND WEATHER TYPE FOR
TODAY AND TONIGHT.
CURRENTLY...WATER VAPOR SATELLITE LOOP INDICATES THE NEXT UPPER
LEVEL SHORTWAVE TO AFFECT THE STATE TODAY WAS OVER NORTH CENTRAL
MONTANA/SOUTHERN SASKATCHEWAN/ALBERTA. AT THE SURFACE...LOW PRESSURE
WAS CENTERED OVER THE SOUTHERN BORDER OF ALBERTA/SASKATCHEWAN WITH A
TROUGH EXTENDING SOUTHEAST ACROSS EASTERN MONTANA. WIDESPREAD FOG
WITH VISIBILITIES RANGING FROM 1/4 MILE TO 1 MILE EXTENDED ACROSS
NORTHWESTERN AND MUCH OF CENTRAL NORTH DAKOTA.
TODAY THE UPPER LEVEL LOW/TROUGH IS PROGGED TO ENTER WESTERN NORTH
DAKOTA THIS MORNING AND ENTER CENTRAL NORTH DAKOTA THIS
AFTERNOON...EXITING NORTH DAKOTA SUNDAY MORNING. AT THE
SURFACE...THE SURFACE LOW AND ATTENDANT WARM FRONT IS FORECAST TO
MOVE EAST TODAY. THE LOW SHOULD MOVE EAST ACROSS SOUTHERN
SASKATCHEWAN/MANITOBA...WITH THE WARM FRONT ENTERING WESTERN NORTH
DAKOTA THIS MORNING...AND CENTRAL NORTH DAKOTA THIS AFTERNOON.
REGARDING THE FOG...AS THE AFOREMENTIONED SYSTEM MOVES INTO WESTERN
NORTH DAKOTA VISIBILITIES SHOULD IMPROVE WITH SUFFICIENT LOW TO MID
LEVEL MIXING. THE HRRR VISIBILITY PROGS SUPPORT THIS AS WELL. AREAS
OF FOG SHOULD PERSIST IN CENTRAL NORTH DAKOTA INTO THE
AFTERNOON...IMPROVING VISIBILITIES WITH TIME FROM WEST TO EAST AS THE
LOW PRESSURE SYSTEM ADVANCES EASTWARD.
THE SHORTWAVE AND SURFACE WARM FRONT WILL ALSO BRING LIGHT SCATTERED
PRECIPITATION TODAY AND TONIGHT. LOOKING AT INCREASING CHANCES THIS
MORNING IN THE WEST...EXPANDING INTO CENTRAL NORTH DAKOTA THIS
AFTERNOON. WARM ADVECTION ALOFT WILL RESULT IN MIXED PRECIPITATION
OF FREEZING DRIZZLE OR DRIZZLE EARLY THIS MORNING WITH CHANCES OF
LIGHT RAIN/DRIZZLE THIS AFTERNOON IN THE WEST AS TEMPERATURES RISE
INTO THE 30S. FARTHER EAST FREEZING DRIZZLE OR LIGHT SNOW SHOULD BE
THE PREDOMINANT WEATHER TYPE.
TONIGHT THE MAIN ENERGY FROM THE UPPER LEVEL TROUGH SHOULD KEEP THE
CHANCE OF PRECIPITATION CONFINED TO THE NORTH CENTRAL AND JAMES
RIVER VALLEY AND EASTWARD. FREEZING DRIZZLE OR LIGHT SNOW WOULD BE
THE MAIN WEATHER TYPE THERE TONIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 330 AM CST SAT DEC 20 2014
A WINTRY MIX POSSIBLE SUNDAY EVENING INTO MONDAY NIGHT...FOLLOWED
BY SNOWFALL POTENTIAL EARLY NEXT WEEK IMPACTING CHRISTMAS TRAVEL
HIGHLIGHT THE EXTENDED FORECAST.
FOR THE 00 UTC GUIDANCE SUITE...WHILE IN AGREEMENT ON GENERAL
FEATURES THROUGH THE EXTENDED FORECAST...SPATIAL DIFFERENCES IN
THE MASS FIELDS AND TIMING RESULT IN NON-TRIVIAL IMPACTS TO
SENSIBLE WEATHER THROUGH THE PERIOD. OVERALL...WEIGHED HEAVILY ON
THE 00 UTC ECMWF AND 03 UTC SREF WHICH RESIDE IN THE MIDDLE OF THE
ENVELOPE OF SOLUTIONS. FOR SUNDAY...A LEAD SHORTWAVE EJECTING OUT
OF THE ROCKIES IS FORECAST TO RESULT IN A RAIN AND SNOW MIX
DEPENDING ON SURFACE TEMPERATURES ACROSS WESTERN NORTH DAKOTA IN
THE AFTERNOON.
THE CHALLENGE IS SUNDAY EVENING INTO MONDAY NIGHT IN REGARDS TO
PRECIPITATION TYPE ACROSS CENTRAL NORTH DAKOTA. A MELTING LAYER
ALOFT ABOVE SUB-FREEZING SURFACE TEMPERATURES IS FORECAST TO
EXIST. HOWEVER...DRY AIR IN THE 900-750 MB LAYER WILL HAVE TO BE
SATURATED FOR PRECIPITATION TO REACH THE GROUND. THUS ENTERS THE
UNCERTAINTY AS TO HOW MUCH OF THE MELTING LAYER WILL REMAIN POST-
SATURATION DUE TO THE WET-BULB EFFECT. THERE APPEARS TO BE A BRIEF
WINDOW...ESPECIALLY ACROSS SOUTH CENTRAL NORTH DAKOTA...FOR THE
WARM LAYER TO BE AROUND +2 TO +2.5 C AROUND 00-03 UTC FOR A WINTRY
MIX OF FREEZING RAIN...SLEET AND MELTED SNOW TO BE POSSIBLE.
OVERALL AMOUNTS WILL BE LIGHT WITH THE COLUMN QUICKLY COOLING TO
SUPPORT ALL SNOW BETWEEN 03-06 UTC. THEREAFTER...ATTENTION TURNS
TO CYCLOGENESIS ACROSS THE EASTERN DAKOTAS AND INTO THE UPPER
MISSISSIPPI VALLEY MONDAY. THE 00 UTC DETERMINISTIC AND ENSEMBLE
SOLUTIONS SHOW A VARIED UPPER LEVEL LOW POSITION FROM NORTH
DAKOTA ON THE NAM TO IOWA ON THE GFS...WITH THE SREF AND ECMWF IN
BETWEEN. THUS...WIDESPREAD LIGHT SNOW IS EXPECTED FOR THE AREA
MONDAY ON ALL SOLUTIONS...WITH HIGHER AMOUNTS IN BANDING POSSIBLE.
HOWEVER...UNCERTAINTY IN THESE BANDS IS RATHER HIGH UNTIL THE MASS
FIELDS COME INTO BETTER AGREEMENT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 1008 AM CST SAT DEC 20 2014
LIFR CEILINGS/VISIBILITIES CONTINUE AT KMOT AND KJMS. KBIS HAS
IMPROVED FROM IFR TO NOW VFR. FARTHER WEST KISN AND KDIK SHOULD
REMAIN VFR. STRATUS AND FOG SHOULD ERODE FROM WEST TO EAST AS AN
APPROACHING SYSTEM BRINGS A DRIER SOUTHWEST FLOW. KMOT SHOULD
BECOME VFR BEFORE/BY 18-19Z. KJMS NOT IMPROVING UNTIL AROUND MID
TO LATE AFTERNOON. THERE IS A RISK OF ISOLATED TO SCATTERED MIXED
PRECIPITATION AT ALL TAF SITES THIS MORNING AND AFTERNOON. DID NOT
MENTION IN TAFS AS LESS THAN 50 PERCENT CHANCE AND ONLY TRACE
LIQUID EXPECTED.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 2 PM CST THIS AFTERNOON FOR NDZ002>005-
011>013-022-023-025-036-037-048-051.
&&
$$
UPDATE...NH
SHORT TERM...JV
LONG TERM...AYD
AVIATION...JV
AREA FORECAST DISCUSSION
NWS BISMARCK ND
616 AM CST SAT DEC 20 2014
.UPDATE...
ISSUED AT 616 AM CST SAT DEC 20 2014
MID LEVEL CLOUD COVER ACROSS WESTERN NORTH DAKOTA HAS LEAD TO THE
SEEDING OF THE LOW LEVEL STRATUS ACROSS THE FAR NORTHWEST. THE
RESULT IS LIGHT FLURRIES AND GREATLY IMPROVED VISIBILITIES FROM
THE PREVIOUS DENSE FOG. THUS...LET THE DENSE FOG ADVISORY EXPIRE
ON TIME FOR DIVIDE AND WILLIAMS COUNTIES. ELSEWHERE...GIVEN
OBSERVED TRENDS AND THE 11 UTC HRRR VISIBILITY FORECAST...EXTENDED
THE REMAINDER OF THE ADVISORY THROUGH 16 UTC AND ADDED LAMOURE AND
DICKEY COUNTIES. GIVEN THE TRENDS IN THE HRRR...PORTIONS OF THE
ADVISORY ACROSS THE JAMES RIVER VALLEY MAY NEED TO BE EXTENDED
INTO THE AFTERNOON.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 352 AM CST SAT DEC 20 2014
MAIN CONCERNS IN THE SHORT TERM ARE THE PERSISTENT FOG IN THE NORTH
AND CENTRAL TODAY...AND PRECIPITATION CHANCES AND WEATHER TYPE FOR
TODAY AND TONIGHT.
CURRENTLY...WATER VAPOR SATELLITE LOOP INDICATES THE NEXT UPPER
LEVEL SHORTWAVE TO AFFECT THE STATE TODAY WAS OVER NORTH CENTRAL
MONTANA/SOUTHERN SASKATCHEWAN/ALBERTA. AT THE SURFACE...LOW PRESSURE
WAS CENTERED OVER THE SOUTHERN BORDER OF ALBERTA/SASKATCHEWAN WITH A
TROUGH EXTENDING SOUTHEAST ACROSS EASTERN MONTANA. WIDESPREAD FOG
WITH VISIBILITIES RANGING FROM 1/4 MILE TO 1 MILE EXTENDED ACROSS
NORTHWESTERN AND MUCH OF CENTRAL NORTH DAKOTA.
TODAY THE UPPER LEVEL LOW/TROUGH IS PROGGED TO ENTER WESTERN NORTH
DAKOTA THIS MORNING AND ENTER CENTRAL NORTH DAKOTA THIS
AFTERNOON...EXITING NORTH DAKOTA SUNDAY MORNING. AT THE
SURFACE...THE SURFACE LOW AND ATTENDANT WARM FRONT IS FORECAST TO
MOVE EAST TODAY. THE LOW SHOULD MOVE EAST ACROSS SOUTHERN
SASKATCHEWAN/MANITOBA...WITH THE WARM FRONT ENTERING WESTERN NORTH
DAKOTA THIS MORNING...AND CENTRAL NORTH DAKOTA THIS AFTERNOON.
REGARDING THE FOG...AS THE AFOREMENTIONED SYSTEM MOVES INTO WESTERN
NORTH DAKOTA VISIBILITIES SHOULD IMPROVE WITH SUFFICIENT LOW TO MID
LEVEL MIXING. THE HRRR VISIBILITY PROGS SUPPORT THIS AS WELL. AREAS
OF FOG SHOULD PERSIST IN CENTRAL NORTH DAKOTA INTO THE
AFTERNOON...IMPROVING VISIBILITIES WITH TIME FROM WEST TO EAST AS THE
LOW PRESSURE SYSTEM ADVANCES EASTWARD.
THE SHORTWAVE AND SURFACE WARM FRONT WILL ALSO BRING LIGHT SCATTERED
PRECIPITATION TODAY AND TONIGHT. LOOKING AT INCREASING CHANCES THIS
MORNING IN THE WEST...EXPANDING INTO CENTRAL NORTH DAKOTA THIS
AFTERNOON. WARM ADVECTION ALOFT WILL RESULT IN MIXED PRECIPITATION
OF FREEZING DRIZZLE OR DRIZZLE EARLY THIS MORNING WITH CHANCES OF
LIGHT RAIN/DRIZZLE THIS AFTERNOON IN THE WEST AS TEMPERATURES RISE
INTO THE 30S. FARTHER EAST FREEZING DRIZZLE OR LIGHT SNOW SHOULD BE
THE PREDOMINANT WEATHER TYPE.
TONIGHT THE MAIN ENERGY FROM THE UPPER LEVEL TROUGH SHOULD KEEP THE
CHANCE OF PRECIPITATION CONFINED TO THE NORTH CENTRAL AND JAMES
RIVER VALLEY AND EASTWARD. FREEZING DRIZZLE OR LIGHT SNOW WOULD BE
THE MAIN WEATHER TYPE THERE TONIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 330 AM CST SAT DEC 20 2014
A WINTRY MIX POSSIBLE SUNDAY EVENING INTO MONDAY NIGHT...FOLLOWED
BY SNOWFALL POTENTIAL EARLY NEXT WEEK IMPACTING CHRISTMAS TRAVEL
HIGHLIGHT THE EXTENDED FORECAST.
FOR THE 00 UTC GUIDANCE SUITE...WHILE IN AGREEMENT ON GENERAL
FEATURES THROUGH THE EXTENDED FORECAST...SPATIAL DIFFERENCES IN
THE MASS FIELDS AND TIMING RESULT IN NON-TRIVIAL IMPACTS TO
SENSIBLE WEATHER THROUGH THE PERIOD. OVERALL...WEIGHED HEAVILY ON
THE 00 UTC ECMWF AND 03 UTC SREF WHICH RESIDE IN THE MIDDLE OF THE
ENVELOPE OF SOLUTIONS. FOR SUNDAY...A LEAD SHORTWAVE EJECTING OUT
OF THE ROCKIES IS FORECAST TO RESULT IN A RAIN AND SNOW MIX
DEPENDING ON SURFACE TEMPERATURES ACROSS WESTERN NORTH DAKOTA IN
THE AFTERNOON.
THE CHALLENGE IS SUNDAY EVENING INTO MONDAY NIGHT IN REGARDS TO
PRECIPITATION TYPE ACROSS CENTRAL NORTH DAKOTA. A MELTING LAYER
ALOFT ABOVE SUB-FREEZING SURFACE TEMPERATURES IS FORECAST TO
EXIST. HOWEVER...DRY AIR IN THE 900-750 MB LAYER WILL HAVE TO BE
SATURATED FOR PRECIPITATION TO REACH THE GROUND. THUS ENTERS THE
UNCERTAINTY AS TO HOW MUCH OF THE MELTING LAYER WILL REMAIN POST-
SATURATION DUE TO THE WET-BULB EFFECT. THERE APPEARS TO BE A BRIEF
WINDOW...ESPECIALLY ACROSS SOUTH CENTRAL NORTH DAKOTA...FOR THE
WARM LAYER TO BE AROUND +2 TO +2.5 C AROUND 00-03 UTC FOR A WINTRY
MIX OF FREEZING RAIN...SLEET AND MELTED SNOW TO BE POSSIBLE.
OVERALL AMOUNTS WILL BE LIGHT WITH THE COLUMN QUICKLY COOLING TO
SUPPORT ALL SNOW BETWEEN 03-06 UTC. THEREAFTER...ATTENTION TURNS
TO CYCLOGENESIS ACROSS THE EASTERN DAKOTAS AND INTO THE UPPER
MISSISSIPPI VALLEY MONDAY. THE 00 UTC DETERMINISTIC AND ENSEMBLE
SOLUTIONS SHOW A VARIED UPPER LEVEL LOW POSITION FROM NORTH
DAKOTA ON THE NAM TO IOWA ON THE GFS...WITH THE SREF AND ECMWF IN
BETWEEN. THUS...WIDESPREAD LIGHT SNOW IS EXPECTED FOR THE AREA
MONDAY ON ALL SOLUTIONS...WITH HIGHER AMOUNTS IN BANDING POSSIBLE.
HOWEVER...UNCERTAINTY IN THESE BANDS IS RATHER HIGH UNTIL THE MASS
FIELDS COME INTO BETTER AGREEMENT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 616 AM CST SAT DEC 20 2014
LIFR CEILINGS/VISIBILITIES CONTINUE AT KMOT AND KJMS. KBIS WAS
VARYING FROM IFR TO LIFR. FARTHER WEST KISN HAD JUST IMPROVED TO
VFR. KDIK SHOULD REMAIN VFR. STRATUS AND FOG SHOULD ERODE FROM
WEST TO EAST AS AN APPROACHING SYSTEM BRINGS A DRIER SOUTHWEST
FLOW. KMOT AND KBIS SHOULD BECOME VFR BEFORE/BY 18Z. KJMS NOT
IMPROVING UNTIL AROUND MID TO LATE AFTERNOON. THERE IS A RISK OF
ISOLATED TO SCATTERED MIXED PRECIPITATION AT KDIK/KISN THIS
MORNING...AND TO ALL TAF SITES THIS AFTERNOON. DID NOT MENTION IN
TAFS AS LESS THAN 50 PERCENT CHANCE.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR NDZ002>005-
010>013-019>023-025-035>037-048-051.
&&
$$
UPDATE...AYD
SHORT TERM...JV
LONG TERM...AYD
AVIATION...JV
AREA FORECAST DISCUSSION
NWS BISMARCK ND
353 AM CST SAT DEC 20 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 352 AM CST SAT DEC 20 2014
MAIN CONCERNS IN THE SHORT TERM ARE THE PERSISTENT FOG IN THE NORTH
AND CENTRAL TODAY...AND PRECIPITATION CHANCES AND WEATHER TYPE FOR
TODAY AND TONIGHT.
CURRENTLY...WATER VAPOR SATELLITE LOOP INDICATES THE NEXT UPPER
LEVEL SHORTWAVE TO AFFECT THE STATE TODAY WAS OVER NORTH CENTRAL
MONTANA/SOUTHERN SASKATCHEWAN/ALBERTA. AT THE SURFACE...LOW PRESSURE
WAS CENTERED OVER THE SOUTHERN BORDER OF ALBERTA/SASKATCHEWAN WITH A
TROUGH EXTENDING SOUTHEAST ACROSS EASTERN MONTANA. WIDESPREAD FOG
WITH VISIBILITIES RANGING FROM 1/4 MILE TO 1 MILE EXTENDED ACROSS
NORTHWESTERN AND MUCH OF CENTRAL NORTH DAKOTA.
TODAY THE UPPER LEVEL LOW/TROUGH IS PROGGED TO ENTER WESTERN NORTH
DAKOTA THIS MORNING AND ENTER CENTRAL NORTH DAKOTA THIS
AFTERNOON...EXITING NORTH DAKOTA SUNDAY MORNING. AT THE
SURFACE...THE SURFACE LOW AND ATTENDANT WARM FRONT IS FORECAST TO
MOVE EAST TODAY. THE LOW SHOULD MOVE EAST ACROSS SOUTHERN
SASKATCHEWAN/MANITOBA...WITH THE WARM FRONT ENTERING WESTERN NORTH
DAKOTA THIS MORNING...AND CENTRAL NORTH DAKOTA THIS AFTERNOON.
REGARDING THE FOG...AS THE AFOREMENTIONED SYSTEM MOVES INTO WESTERN
NORTH DAKOTA VISIBILITIES SHOULD IMPROVE WITH SUFFICIENT LOW TO MID
LEVEL MIXING. THE HRRR VISIBILITY PROGS SUPPORT THIS AS WELL. AREAS
OF FOG SHOULD PERSIST IN CENTRAL NORTH DAKOTA INTO THE
AFTERNOON...IMPROVING VISIBILITIES WITH TIME FROM WEST TO EAST AS THE
LOW PRESSURE SYSTEM ADVANCES EASTWARD.
THE SHORTWAVE AND SURFACE WARM FRONT WILL ALSO BRING LIGHT SCATTERED
PRECIPITATION TODAY AND TONIGHT. LOOKING AT INCREASING CHANCES THIS
MORNING IN THE WEST...EXPANDING INTO CENTRAL NORTH DAKOTA THIS
AFTERNOON. WARM ADVECTION ALOFT WILL RESULT IN MIXED PRECIPITATION
OF FREEZING DRIZZLE OR DRIZZLE EARLY THIS MORNING WITH CHANCES OF
LIGHT RAIN/DRIZZLE THIS AFTERNOON IN THE WEST AS TEMPERATURES RISE
INTO THE 30S. FARTHER EAST FREEZING DRIZZLE OR LIGHT SNOW SHOULD BE
THE PREDOMINANT WEATHER TYPE.
TONIGHT THE MAIN ENERGY FROM THE UPPER LEVEL TROUGH SHOULD KEEP THE
CHANCE OF PRECIPITATION CONFINED TO THE NORTH CENTRAL AND JAMES
RIVER VALLEY AND EASTWARD. FREEZING DRIZZLE OR LIGHT SNOW WOULD BE
THE MAIN WEATHER TYPE THERE TONIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 330 AM CST SAT DEC 20 2014
A WINTRY MIX POSSIBLE SUNDAY EVENING INTO MONDAY NIGHT...FOLLOWED
BY SNOWFALL POTENTIAL EARLY NEXT WEEK IMPACTING CHRISTMAS TRAVEL
HIGHLIGHT THE EXTENDED FORECAST.
FOR THE 00 UTC GUIDANCE SUITE...WHILE IN AGREEMENT ON GENERAL
FEATURES THROUGH THE EXTENDED FORECAST...SPATIAL DIFFERENCES IN
THE MASS FIELDS AND TIMING RESULT IN NON-TRIVIAL IMPACTS TO
SENSIBLE WEATHER THROUGH THE PERIOD. OVERALL...WEIGHED HEAVILY ON
THE 00 UTC ECMWF AND 03 UTC SREF WHICH RESIDE IN THE MIDDLE OF THE
ENVELOPE OF SOLUTIONS. FOR SUNDAY...A LEAD SHORTWAVE EJECTING OUT
OF THE ROCKIES IS FORECAST TO RESULT IN A RAIN AND SNOW MIX
DEPENDING ON SURFACE TEMPERATURES ACROSS WESTERN NORTH DAKOTA IN
THE AFTERNOON.
THE CHALLENGE IS SUNDAY EVENING INTO MONDAY NIGHT IN REGARDS TO
PRECIPITATION TYPE ACROSS CENTRAL NORTH DAKOTA. A MELTING LAYER
ALOFT ABOVE SUB-FREEZING SURFACE TEMPERATURES IS FORECAST TO
EXIST. HOWEVER...DRY AIR IN THE 900-750 MB LAYER WILL HAVE TO BE
SATURATED FOR PRECIPITATION TO REACH THE GROUND. THUS ENTERS THE
UNCERTAINTY AS TO HOW MUCH OF THE MELTING LAYER WILL REMAIN POST-
SATURATION DUE TO THE WET-BULB EFFECT. THERE APPEARS TO BE A BRIEF
WINDOW...ESPECIALLY ACROSS SOUTH CENTRAL NORTH DAKOTA...FOR THE
WARM LAYER TO BE AROUND +2 TO +2.5 C AROUND 00-03 UTC FOR A WINTRY
MIX OF FREEZING RAIN...SLEET AND MELTED SNOW TO BE POSSIBLE.
OVERALL AMOUNTS WILL BE LIGHT WITH THE COLUMN QUICKLY COOLING TO
SUPPORT ALL SNOW BETWEEN 03-06 UTC. THEREAFTER...ATTENTION TURNS
TO CYCLOGENESIS ACROSS THE EASTERN DAKOTAS AND INTO THE UPPER
MISSISSIPPI VALLEY MONDAY. THE 00 UTC DETERMINISTIC AND ENSEMBLE
SOLUTIONS SHOW A VARIED UPPER LEVEL LOW POSITION FROM NORTH
DAKOTA ON THE NAM TO IOWA ON THE GFS...WITH THE SREF AND ECMWF IN
BETWEEN. THUS...WIDESPREAD LIGHT SNOW IS EXPECTED FOR THE AREA
MONDAY ON ALL SOLUTIONS...WITH HIGHER AMOUNTS IN BANDING POSSIBLE.
HOWEVER...UNCERTAINTY IN THESE BANDS IS RATHER HIGH UNTIL THE MASS
FIELDS COME INTO BETTER AGREEMENT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1223 AM CST SAT DEC 20 2014
IFR CEILINGS/VISIBILITIES CONTINUE AT KISN KMOT AND KJMS. LATEST
SATELLITE AND MESOSCALE HRRR INDICATE THE STRATUS/FOG SHOULD MOVE
INTO KBIS SHORTLY AFTER 06 UTC. WILL LEAVE KDIK OUT OF THE FOG
TONIGHT AS LATEST ITERATIONS OF THE HRRR BACK OFF ON THE WESTERN
EXTENT OF THE STRATUS. STRATUS WILL ERODE FROM WEST TO EAST ON
SATURDAY AS AN APPROACHING SYSTEM BRINGS A DRIER SOUTHWEST FLOW.
KISN AND KBIS SHOULD CLEAR DURING THE MORNING...KMOT AND KJMS
CLEARING SATURDAY AFTERNOON.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR
NDZ001>005-009>013-019>023-025-035>037.
&&
$$
SHORT TERM...JV
LONG TERM...AYD
AVIATION...TWH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1223 AM CST SAT DEC 20 2014
.UPDATE...
ISSUED AT 1223 AM CST SAT DEC 20 2014
LATEST HRRR CONTINUES TO INDICATE LOWER VISIBILITIES IN FOG
REMAINING OVER NORTHERN AND CENTRAL/EASTERN NORTH DAKOTA...WITH THE
SOUTHWEST MAINLY STRATUS-FREE. THE HRRR ALSO INDICATES SOME ISOLATED
POCKETS OF FREEZING DRIZZLE/RAIN OVER NORTH CENTRAL INTO
NORTHEASTERN NORTH DAKOTA. HAVE ADDED MENTION OF PATCHY FREEZING
DRIZZLE TO MAINLY TIOGA/STANLEY TO MINOT/GARRISON...TO THE TURTLE
MOUNTAINS/JAMESTOWN AREAS THROUGH THE REST OF TONIGHT UNTIL AROUND 9
AM SATURDAY MORNING. THIS AREA THE HRRR IS TARGETING IS ALSO WHERE
AN UPPER LEVEL SHORTWAVE MOVES SOUTHEAST ACROSS THIS
REGION...EXITING INTO MINNESOTA LATER THIS MORNING. OTHERWISE
CURRENT FORECAST ON TRACK AND HAS A GOOD HANDLE ON FOG...WITH THE
DENSE FOG ADVISORY FROM CROSBY/WILLISTON TO MINOT/BISMARCK TO THE
TURTLE MOUNTAINS/JAMESTOWN. WILL RE-EVALUATE LATER THIS MORNING FOR
ANY CHANGES/EXTENSIONS OF THIS ADVISORY.
UPDATE ISSUED AT 924 PM CST FRI DEC 19 2014
BASED ON LATEST SATELLITE LOOP...SURFACE OBS AND REPORTS...HAVE
DECIDED TO EXTEND THE DENSE FOG ADVISORY FARTHER TO THE SOUTH AND
EAST. REPORTS AND OBSERVATIONS OF VISIBILITIES DURING THE PAST
HOUR SHOW QUARTER MILE OR LESS VSBYS FROM THE HAZEN AREA EAST
ACROSS NORTHERN BURLEIGH COUNTY AND INTO KIDDER AND STUTSMAN
COUNTIES. FARTHER NORTH AND EAST...VISIBILITIES ARE NOT AS LOW
OVER THE TURTLE MOUNTAINS DOWN INTO FOSTER COUNTY NORTH OF
JAMESTOWN. HOWEVER...LATEST HRRR DOES INDICATE LOWER VISIBILITIES
WORKING THIS WAY LATE TONIGHT INTO SATURDAY MORNING. THERE HAS
BEEN LOW STRATUS AND FOG...ESPECIALLY IN THE TURTLE MOUNTAINS AREA
ALL DAY AND ROADS MAY BE SLIPPERY. ALTHOUGH THERE HAVE BEEN NO
REPORTS AS OF YET...THERE HAS BEEN REPORTS OF FREEZING DRIZZLE
JUST TO THE NORTH IN CANADA AND INTO NORTHEAST NORTH DAKOTA.
UPDATE ISSUED AT 549 PM CST FRI DEC 19 2014
MAIN UPDATE THIS AFTERNOON IS TO EXPAND THE DENSE FOG ADVISORY TO
INCLUDE DIVIDE AND WILLIAMS COUNTIES IN NORTHWEST NORTH
DAKOTA...AND MCLEAN...SHERIDAN AND WELLS COUNTIES IN CENTRAL NORTH
DAKOTA. LATEST SURFACE OBSERVATIONS AND WEATHER CAMERAS INDICATE
THE LOWEST VISIBILITIES ARE ALONG THE PERIPHERY OF THE STRATUS
LAYER FROM DIVIDE AND WILLIAMS COUNTIES SOUTHEAST TO AROUND
GARRISON IN MCLEAN COUNTY AND THEN EAST TOWARD HARVEY IN WELLS
COUNTY. LATEST HRRR MODEL ITERATION SHOWS THE STRATUS EXPANDING
SOUTH AND WEST THIS EVENING...WHICH LOOKS TO VERIFY FROM LAST FEW
SATELLITE IMAGES. OTHERWISE ONLY MINOR UPDATES FOR SKY COVER AND
POPULATED LATEST SENSIBLE WEATHER ELEMENTS.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 303 PM CST FRI DEC 19 2014
.SHORT TERM...TONIGHT THROUGH SATURDAY...
PERSISTENT FOG ACROSS THE NORTH WITH CURRENT SATELLITE LOOPS SHOWING
THE STRATUS IS EXPANDING SOUTH INTO THE JAMES NORTHERN JAMES RIVER
VALLEY. NAM BUFKIT SOUNDINGS HAVE A SOLID STRATUS AND FOG LOW LEVEL
SOUNDING FROM WILLISTON THROUGH MINOT WHILE THE GFS MIXES IT OUT
THIS EVENING. WILL LEAN TO THE NAM AND KEEP FOG AND LOW CLOUDS
THOUGH THE NORTH AND EAST CENTRAL TONIGHT. FURTHER ISSUES INVOLVE
VSBYS AS LOW AS ONE QUARTER MILE NEAR TIOGA TO STANLEY. DO NOT
SEE MUCH IMPROVEMENT THERE AND SHOULD SEE LOWER VSBYS IN MINOT
LATER TONIGHT AFTER SUNSET. WILL GO WITH A DENSE FOG ADVISORY FROM
TIOGA TO STANLEY THROUGH 9 PM THEN EXPAND IT EAST THROUGH MINOT
AND TO BOTTINEAU AND MCHENRY COUNTIES THROUGH SATURDAY MORNING.
THE FOG WILL ALSO INSULATE A BIT SO HAVE RAISED TEMPERATURES FOR
OVERNIGHT NIGHT LOWS.
ON SATURDAY...WEAK SHORTWAVE WILL BRING LIGHT AND SPOTTY
PRECIPITATION. EXPECT A WINTRY MIX OF FREEZING RAIN...SOME SLEET AND
SNOW BUT LITTLE ACCUMULATIONS.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 303 PM CST FRI DEC 19 2014
FOCUS IN THE LONG TERM IS ON THE LARGE SCALE UPPER LEVEL TROUGH THAT
DEVELOPS OVER THE NORTHERN PLAINS SUNDAY AND DEEPENS SIGNIFICANTLY
OVER THE CENTRAL UNITED STATES INTO EARLY NEXT WEEK.
PAST RUNS OF THE ECMWF AND GFS HAVE CONSISTENTLY SHOWN A DEEPENING
TROUGH OVER THE CENTRAL UNITED STATES SUNDAY INTO EARLY NEXT WEEK.
THE LATEST 12 UTC RUNS OF THE ECMWF AND GFS HAVE BACKED THE SYSTEM
UP A BIT...DEVELOPING A CUT OFF UPPER LEVEL LOW OVER SOUTH DAKOTA
MONDAY WHICH SLOWLY PROPAGATES EAST INTO TUESDAY. THESE SOLUTIONS
BOTH SHOW MORE QPF OVER CENTRAL AND WESTERN NORTH DAKOTA THAN
PREVIOUS MODEL RUNS.
VERTICAL PROFILES ALSO LOOK TO BE BETTER MIXED AFTER THE WEAK
SURFACE COLD FRONT MOVES THROUGH SUNDAY NIGHT. BEFORE THE FRONT
PASSES A LIGHT WINTRY MIX OF FREEZING RAIN...SLEET...RAIN...AND SNOW
WILL BE POSSIBLE ACROSS THE WEST SUNDAY MORNING AND AFTERNOON. ANY
ACCUMULATIONS WILL BE MINOR. STARTING SUNDAY NIGHT THE SOUTHWEST MAY
SEE A BRIEF PERIOD OF RAIN MIXED WITH SNOW...HOWEVER FOR THE REST OF
THE STATE ALL SNOW IS ANTICIPATED. MONDAY AND TUESDAY PRECIPITATION
IS FORECAST AS ALL SNOW AS WELL FOR ALL OF CENTRAL AND WESTERN NORTH
DAKOTA. WITH THAT SAID IF MODEL SOLUTIONS PROGRESS THE TROUGH ALONG
QUICKER SUNDAY NIGHT AND MONDAY...PROFILES ALOFT COULD BE TO DRY FOR
ICE CRYSTALS AND WESTERN AND CENTRAL NORTH DAKOTA COULD ONCE AGAIN
SEE SOME FREEZING RAIN OR DRIZZLE.
EARLY ESTIMATES ON SNOW ACCUMULATIONS FOR MONDAY INTO TUESDAY RANGE
FROM AROUND 2 INCHES WEST TO AN INCH ELSEWHERE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1223 AM CST SAT DEC 20 2014
IFR CEILINGS/VISIBILITIES CONTINUE AT KISN KMOT AND KJMS. LATEST
SATELLITE AND MESOSCALE HRRR INDICATE THE STRATUS/FOG SHOULD MOVE
INTO KBIS SHORTLY AFTER 06 UTC. WILL LEAVE KDIK OUT OF THE FOG
TONIGHT AS LATEST ITERATIONS OF THE HRRR BACK OFF ON THE WESTERN
EXTENT OF THE STRATUS. STRATUS WILL ERODE FROM WEST TO EAST ON
SATURDAY AS AN APPROACHING SYSTEM BRINGS A DRIER SOUTHWEST FLOW.
KISN AND KBIS SHOULD CLEAR DURING THE MORNING...KMOT AND KJMS
CLEARING SATURDAY AFTERNOON.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR
NDZ001>005-009>013-019>023-025-035>037.
&&
$$
UPDATE...JV
SHORT TERM...WAA
LONG TERM...MM
AVIATION...TWH
FORECAST DISCUSSION.
A WEAK LEAD SHORTWAVE IS FORECAST TO ROTATE NORTHEAST THROUGH THE
OHIO VALLEY ON MONDAY MORNING...COMBINING WITH THE FRONT EDGE OF
THE NORTHWARD-MOVING MOISTURE. THERE APPEARS TO BE JUST ENOUGH
ISENTROPIC LIFT TO SUPPORT SOME WEAK SHOWERS...MAINLY IN THE
SOUTHERN AND SOUTHEASTERN PORTIONS OF THE FORECAST AREA...WHERE A
20-POP HAS BEEN USED IN THE FORECAST. HOWEVER...THIS SHORTWAVE
WILL BE WEAKENING WITH TIME...AND WIDESPREAD PRECIPITATION IS NOT
LIKELY TO OCCUR. AS THIS LIGHT PRECIPITATION MOVES IN...THE REGION
WILL BE COMING OUT OF ANOTHER CHILLY MORNING...WITH TEMPERATURES
ONLY EXPECTED TO RISE ABOVE FREEZING JUST BEFORE THE PRECIPITATION
ARRIVES. A WORST-CASE SCENARIO COULD SUPPORT SOME LIGHT FZRA NEAR
THE OHIO RIVER AT AROUND 12Z...BUT IT APPEARS THAT THE
PRECIPITATION WILL BE LIGHT/SPARSE ENOUGH (AND TEMPERATURES
WARMING JUST SOON ENOUGH) TO MAKE THIS A LOW-PROBABILITY SCENARIO.
TEMPERATURES ON MONDAY WILL WARM SIGNIFICANTLY BEYOND VALUES ON
SUNDAY...THANKS TO WARM ADVECTION...AND EVEN IN THE ABSENCE OF
MUCH INSOLATION. TEMPERATURES ACROSS THE ILN FORECAST AREA SHOULD
RANGE FROM THE LOWER-TO- MID 40S IN THE NORTH TO THE LOWER 50S IN
THE SOUTH. THESE WARMING TEMPERATURES WILL BE AIDED BY A LACK OF
PRECIPITATION...AS THE FORWARD PROGRESSION OF THE DEVELOPING LOW
PRESSURE IS NOT PARTICULARLY FAST.
CHANCES FOR PRECIPITATION WILL INCREASE AHEAD OF THE PROGRESSION
OF THE MID-LEVEL LOW...WHICH WILL BE MOVING NORTHEAST INTO THE
GREAT LAKES ON TUESDAY MORNING. AS MOISTURE CONVERGENCE INCREASES
OVER THE LOWER OHIO VALLEY...A SWATH OF SHOWERY PRECIPITATION IS
EXPECTED TO TRANSLATE NORTHEASTWARD AS WELL. THIS ACTIVITY WILL
EVENTUALLY OUTRUN THE SLOWING COLD FRONT...BUT WILL BE AIDED BY
FAVORABLE DIFFLUENT FLOW AHEAD OF THE APPROACHING UPPER JET
STREAK. WHILE THE GREATEST CHANCES FOR PRECIPITATION (AND GREATEST
MODEL OUTPUT QPF) APPEAR TO BE IN THE NORTHWESTERN CWA...THE FOCUS
FOR ANY POTENTIAL FOR THUNDER WILL BE IN THE NORTHERN KENTUCKY AND
SOUTH CENTRAL OHIO. SURFACE-BASED INSTABILITY WILL BE VERY
UNLIKELY...WITH SOME LEVEL OF INVERSION STILL REMAINING IN
PLACE...AS ALSO EVIDENCED BY THE SLIGHTLY DECOUPLED WIND
DIRECTIONS BETWEEN THE SURFACE AND 850MB. HOWEVER...850MB PARCELS
WILL HAVE A ROUGHLY MOIST-ADIABATIC PROFILE ABOVE THEM...WITH 15Z
SPC SREF PARAMETERS INDICATING AT LEAST A CHANCE OF EQUILIBRIUM
LEVELS COLD ENOUGH TO SUPPORT SOME WEAK CONVECTION. THUS...A BRIEF
PERIOD WITH A SLIGHT CHANCE OF THUNDER WAS INCLUDED THURSDAY
MORNING AND AFTERNOON IN THE SOUTHERN/SOUTHEASTERN PORTIONS OF THE
FORECAST AREA.
POPS WILL DECREASE ON TUESDAY EVENING AS THE MID-LEVEL WAVE MOVES
OFF...AND UPPER SUPPORT IS LOST. CHANCES WILL INCREASE AGAIN EARLY
WEDNESDAY MORNING...AS LOW-LEVEL FORCING AND CONVERGENCE BEGINS
TO INCREASE AHEAD OF A DEVELOPING SURFACE LOW. THROUGHOUT THIS
PERIOD...TEMPERATURES WILL BE DOMINATED BY ADVECTION...WITH
NON-DIURNAL CURVES REQUIRED FOR THE FORECAST GRIDS. HIGHS ON
TUESDAY SHOULD RANGE FROM THE LOWER 50S TO UPPER 50S FROM NORTH TO
SOUTH...WITH LITTLE CHANGE IN TEMPERATURE EXPECTED TUESDAY NIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
LOW PRESSURE WILL DEEPEN ALONG A COLD FRONT AT THE BEGINNING OF THE
LONG TERM PERIOD. GFS/CMC ARE SIMILAR IN THE INTENSIFYING PROCESS AS
THE LOW MOVES NORTHEAST FROM THE MIDDLE OHIO VALLEY TO SOUTHEAST
ONTARIO INTO WEDNESDAY NIGHT. THE ECMWF IS A LITTLE STRONGER AND THE
NAM IS A WEAK OUTLIER. HAVE TAKEN A BLEND OF THE GFS/CMC. AS THE
DEEPENING PROCESS OCCURS...WIDESPREAD SHOWERS ARE EXPECTED WEDNESDAY
MORNING. BY WEDNESDAY AFTERNOON...THE COLD FRONT WILL PUSH NORTHEAST
THROUGH THE REGION. THE COVERAGE OF PCPN WILL DECREASE BEHIND
FRONTAL PASSAGE AS DRIER SLOT OF AIR ALOFT MOVES IN BRIEFLY. BY
WEDNESDAY NIGHT...SOME WRAP AROUND MOISTURE WILL OCCUR...BUT
COVERAGE LOOKS TO BE CHANCE AT BEST. IT WILL BE WARM AHEAD OF THE
FRONT WITH TEMPERATURES DROPPING WEDNESDAY AFTERNOON INTO THE NIGHT.
HIGHS ON WEDNESDAY WILL RANGE FROM THE 50S TO NEAR 60 WITH LOWS
BOTTOMING OUT INTO THE LOWER AND MID 30S BY CHRISTMAS MORNING. IT
SHOULD BECOME COLD ENOUGH FOR A CHANCE OF RAIN/SNOW SHOWERS AND THEN
A CHANCE OF SNOW SHOWERS CHRISTMAS EVE NIGHT. HOWEVER...LITTLE IS
EXPECTED IN THE WAY OF ACCUMULATIONS GIVEN RECENT WARM TEMPERATURES
AND NO REAL FOCUS/FORCING FOR APPRECIABLE SNOWFALL RATES. IT WILL
BECOME BRISK TO LOCALLY WINDY DURING THE PERIOD...BUT WINDS ARE
EXPECTED TO STAY BELOW ADVISORY CRITERIA ATTM.
ON CHRISTMAS DAY...DEEPENING LOW PRESSURE WILL CONTINUE TO MOVE
NORTHEAST AWAY FROM THE REGION. ANY THREAT FOR SNOW SHOWERS WILL
QUICKLY COME TO AN END DURING CHRISTMAS MORNING. BY
AFTERNOON...SKIES SHOULD BECOME PARTLY CLOUDY AS SURFACE RIDGING
QUICKLY BUILDS INTO THE AREA BEHIND DEPARTING SYSTEM. HIGHS ON
CHRISTMAS WILL RANGE FROM THE UPPER 30S TO THE LOWER 40S...NEAR
SEASONAL NORMALS.
FOR THURSDAY NIGHT...SURFACE RIDGE WILL MOVE EAST WITH RETURN
SOUTHWEST FLOW ENSUING ALONG WITH INCREASING CLOUDS AHEAD OF THE
NEXT SYSTEM.
FOR FRIDAY INTO SATURDAY...LOW PRESSURE AND A COLD FRONT WILL MOVE
ACROSS THE GREAT LAKES AND OHIO VALLEY. SYSTEM APPEARS TO BE
MOISTURE STARVED SO WILL CONTINUE WITH LOW CHANCE POPS. WE SHOULD
SEE A WARM UP ON FRIDAY FOLLOWED BY A COOL DOWN SATURDAY IN THE WAKE
OF THE SYSTEM.
BY SUNDAY...HIGH PRESSURE AND MUCH COLDER TEMPERATURES ARE EXPECTED.
HIGHS BY THEN WILL RANGE FROM THE UPPER 20S TO THE LOWER 30S.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
THE EVENING KILN RAOB CONFIRMS SOME DRIER AIR IN THE LOW LEVELS OF
THE ATMOSPHERE. OUR AREA WILL REMAIN UNDER BROKEN CIRRUS FOR THE
BULK OF THE OVERNIGHT HOURS. AS SURFACE HIGH PRESSURE DRIFTS
FURTHER EAST OF THE AREA...SOUTHERLY LOW LEVEL FLOW WILL DRAW
INCREASING MOISTURE UP FROM THE SOUTH LATE TONIGHT INTO MONDAY
MORNING. LATEST SATELLITE IMAGERY REVEALS LOW LEVEL CLOUDS ALREADY
WORKING THEIR WAY FROM TENNESSEE INTO SOUTHERN KENTUCKY. EXPECT AN
MVFR CLOUD DECK TO MOVE IN FROM SOUTH TO NORTH OVER THE TERMINALS
AROUND 10Z TO 13Z MONDAY. ALONG WITH THIS INCREASE IN LOW LEVEL
MOISTURE AND A WEAK UPPER DISTURBANCE WILL COME THE CHANCE FOR
PERHAPS SOME ISOLATED RAIN SHOWERS IN THE MORNING. LATEST HI-RES
MODELS ARE NOT OVERLY EXCITED ABOUT THIS POSSIBILITY BUT THEY DO
HINT AT IT. THUS...WENT WITH VCSH FOR NOW. IF THE RAIN DOES
MATERIALIZE...CANNOT RULE OUT PERHAPS A BRIEF PERIOD OF VERY LIGHT
FZRA AT THE CINCINNATI TERMINALS BEFORE 12Z WITH SURFACE TEMPERATURES
EXPECTED TO BE RIGHT AROUND FREEZING. THE MVFR CLOUD DECK SHOULD
MIX OUT A BIT IN THE AFTERNOON...THEN REDEVELOP BY THE END OF THE
KCVG TAF PERIOD WITH A CHANCE OF SHOWERS AS THE NEXT STORM SYSTEM
APPROACHES FROM THE WEST. WINDS WILL REMAIN LIGHT OUT OF THE
SOUTHEAST TONIGHT...PICKING UP TOWARDS THE END OF THE TAF PERIOD.
OUTLOOK...MVFR TO IFR CIGS AND VSBYS ARE POSSIBLE MONDAY NIGHT
INTO THURSDAY. WINDS WILL PICK UP SIGNIFICANTLY STARTING
WEDNESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...BINAU
SHORT TERM...HATZOS
LONG TERM...HICKMAN
AVIATION...KURZ
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
624 PM EST SUN DEC 21 2014
.SYNOPSIS...
WEAK HIGH PRESSURE EXITS THIS EVENING. SYSTEM CLIPS THE MOUNTAINS
MONDAY. STRONG LOW PRESSURE SYSTEM LIFTS NORTHEAST ACROSS THE
OHIO VALLEY THROUGH CHRISTMAS EVE.
&&
.NEAR TERM /THROUGH MONDAY/...
PREVIOUS FORECAST REMAINS REPRESENTATIVE. NO CHANGES NECESSARY.
PREVIOUS DISCUSSION BELOW...
HIGH PRESSURE AND LIGHT E FLOW HAD MANAGED TO ERADICATE THE
STRATUS ALONG AND E OF THE OHIO RIVER TODAY. THIS HAS ALLOWED FOR
DAYTIME HEATING BUT WILL ALSO ALLOW FOR RADIATIVE COOLING THIS
EVENING.
A WARM WAVE RIDES UP THE SE COAST LATE TONIGHT AND MON. THE
QUESTION IS TO WHAT DEGREE THIS FLAT WAVE CAN THROUGH PRECIPITATION
BACK INTO THE FCST AREA...AND WHEN WILL SUCH PRECIPITATION REACH THE
GROUND GIVEN THE DRY MID LEVEL AIR TO START OUT WITH.
MOST OF THE GUIDANCE SUGGESTS TEMPERATURES NEAR OR JUST BELOW
FREEZING IN THE NRN WV MOUNTAINS...MAINLY ON THE HIGHER PEAKS AND
DOWN THE ERN SLOPES INTO THE GREENBRIER VALLEY. MODELS DEPICT A
WARM LAYER ALOFT WITH TEMPERATURES 1-2C IN THE H925-H85 LAYER. THIS
SUGGESTS MELTING OF SNOW WHICH MEANS THERE COULD BE SLEET AND SNOW
MIXED IN WITH ANY FREEZING RAIN. TEMPERATURES IN CLOUD SUPPORTIVE
OF ICE CRYSTALS ARE LOST EARLY ON AS THE MOIST LAYER BECOMES MORE
SHALLOW. THIS WOULD TEND THE PRECIPITATION BACK TOWARD FREEZING
RAIN OR FREEZING DRIZZLE.
THIS LEAVES THE TIMING OF THE ARRIVAL OF PRECIPITATION CRUCIAL AS
TEMPERATURES SLOWLY CLIMB ABOVE FREEZING IN THE GREENBRIER VALLEY.
CURRENT GRID DEPICTION IS FOR POPS CLIMBING ABOVE 50 YIELDING
MEASURABLE QPF AS TEMPERATURES CLIMB. THIS LIMITS ICE ACCRETION TO
AT MOST A HUNDREDTH AND NOT VERY WIDESPREAD. THE SREF DOES
INTERSECT HIGH POPS WITH POCKETS OF HIGH PROBABILITIES FOR SFC
TEMPERATURES AT OR BELOW FREEZING MON MIDDAY INTO THE AFTERNOON.
COORD WITH WPC/WWD-PBZ-LWX-RNK ON ISSUANCE ADV FOR FREEZING RAIN
POCAHONTAS COUNTY 11-17Z.
THE REMAINDER OF THE FCST AREA SEES A RETURN OF CLOUD COVER
TONIGHT...SETTING THE STAGE FOR ANOTHER GREY DECEMBER DAY...ALTHOUGH
THE CLOUDS DO DECREASE BEHIND THE SYSTEM MON AFTERNOON.
USED NEAR TERM...IN PARTICULARLY THE WRFNMM...RUC AND THE HRRR FOR
TEMPERATURES TONIGHT AND NAM-BASED VALUES FOR THOSE ON MON...WHICH
SHOULD FEATURE A MILDER AFTERNOON.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
5H TROUGH TO DIG OVER THE MIDWEST WITH SEVERAL WAVES RIDING NWD
ALONG THE COAST OF SE US. THIS LEAVES OUR CWA IN THE WARM SECTOR
OF BAROCLINIC FORCING THAT WILL BE TAKING PLACE IN VARIOUS PHASES
THROUGHOUT THE PERIOD. FIRST WEAKER WAVE DEFTLY EXITS TO THE EAST
BY TUESDAY MORNING AND ONLY BROUGHT ISOLD AND LOW CHANCE POPS TO
THE EASTERN MOUNTAINS. WAA WILL BE FULL SWING UNDER SOUTH TO
SOUTHWEST FLOW AND CHANCES FOR ANY PRECIPITATION OF THE FROZEN
VARIETY WILL BE NIL.
A SECOND STRONGER WAVE WILL PUSH NORTH TUESDAY NIGHT AND
WEDNESDAY. MODELS STILL SHOW POOR PHASING BETWEEN NORTHERN AND
SOUTH STREAM SYSTEMS WITH MAIN SFC LOW DEVELOPMENT OCCURRING NORTH
OF THE GREAT LAKES. THIS DELAYS FROPA AND ONSET OF CAA AND PLACES
CWA SQUARELY IN THE WARM SECTOR THROUGH WEDNESDAY. FRONT WILL
FINALLY PUSH THROUGH WEDNESDAY NIGHT WITH PRECIPITATION COMING TO
AN END...MOSTLY BEFORE THE COLDER AIR ON BACKSIDE IS ABLE TO MOVE
IN. THUS...ONLY HAVE VERY LIGHT SNOW AMOUNTS FIGURED FOR THE
MOUNTAINS IN NORTHEASTERN COUNTIES.
USED MAINLY SREF FOR TIMING ONSET OF PRECIP DEVELOPMENT. FOR
TEMPS...USED BC GRIDS WITH A BLEND TOWARD INHERITED FORECAST
TEMPS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
COLD FRONT TO THE EAST OF THE CWA AT THE BEGINNING OF THE
PERIOD...WITH A GRADUAL CHANGE OVER TO SNOW FOR CHRISTMAS EVE NIGHT
AND CHRISTMAS DAY. AT THIS POINT...REALLY NOT EXPECTING MUCH IN
TERMS OF SNOWFALL ACCUMULATIONS. WINDS HOWEVER ON THURSDAY ARE STILL
EXPECTED TO BE GUSTY POST FRONTAL.
AREA DRIES OUT THURSDAY EVENING AS THE LOW PULLS OFF TO THE
NORTHEAST. HIGH PRESSURE THEN BRIEFLY BUILDS IN FOR A BREAK IN
PRECIPITATION. ANOTHER COLD FRONT WILL DROP ACROSS THE AREA OVER THE
WEEKEND...CREATING A CHANCE FOR LIGHT SNOW SHOWERS...AND WILL USHER
IN MUCH COLDER AIR INTO THE REGION. TRENDED TEMPERATURES NEXT
WEEKEND DOWN FROM PREVIOUS FORECAST.
&&
.AVIATION /23Z SUNDAY THROUGH FRIDAY/...
A WEAK WAVE OF LOW PRESSURE MOVES UP ALONG THE SE COAST OVERNIGHT
TONIGHT AND MON...WITH RAIN LIKELY IN THE MOUNTAINS WHERE A WINTRY
MIX PCPN IS FORECASTED THROUGH EARLY MONDAY MORNING. CONSEQUENTLY...VFR
CONDITIONS EXPECTED TO PREVAIL TONIGHT INTO SUNDAY...WITH THE
EXCEPTION OF BKW AND NEARBY CENTRAL MOUNTAINS WHERE LOW STRATUS
SHOULD DEVELOP OVERNIGHT. EXPECT IFR CEILINGS SUPPORTED BY THE
NAM AND LAV GUIDANCE INDICATING IFR CONDITIONS WITH BETTER
CONFIDENCE FROM 15Z TO 18Z. DECIDED TO BRING EARLIER THE LOW
STRATUS OVER BKW STARTING AROUND 09Z WHEN THE NAM SHOWS LOWER
DEWPOINT DEPRESSION...AND BUFKIT SOUNDINGS SHOWS A MORE PRONOUNCED
SATURATED LAYER AROUND 900 FEET.
LOW CEILINGS AND IFR VISIBILITIES ALSO POSSIBLE ACROSS THE EASTERN
SLOPES OF THE NORTHEAST MOUNTAINS ACCOMPANIED BY DRIZZLE OR
FREEZING DRIZZLE OVERNIGHT INTO EARLY SUNDAY.
EASTERLY FLOW COULD WILL GRADUALLY INCREASE OVERNIGHT ACROSS THE
HIGHER ELEVATIONS AS SHOWN BY MODELS AT H925. FLOW WILL CONTINUE
TO INCREASE FROM THE SOUTHEAST ON SUNDAY.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z TUESDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: TIMING AND LOCATION OF A MVFR STRATUS DECK
COULD VARY CONSIDERABLY OVERNIGHT INTO MON.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07
EST 1HRLY 15 16 17 18 19 20 21 22 23 00 01 02
CRW CONSISTENCY M M H H H H H H H H H H
HTS CONSISTENCY M M H H H H H H H H H H
BKW CONSISTENCY H H H M M M M M L L L L
EKN CONSISTENCY H H H H H H H H H H H H
PKB CONSISTENCY M M M M M H H H H H H H
CKB CONSISTENCY M M M M H H H H H H H H
AFTER 00Z TUESDAY...
IFR POSSIBLE IN MOUNTAINS INTO EARLY MON EVENING IN A WINTRY MIX.
IFR POSSIBLE IN RAIN TUE NT INTO WED...CHANGING TO SNOW SHOWERS
WED NT...AS AN INTENSE LOW PRESSURE CENTER PASSES.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...FREEZING RAIN ADVISORY FROM 6 AM TO NOON EST MONDAY FOR WVZ046.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...TRM/RPY/SL/30
NEAR TERM...ARJ/TRM
SHORT TERM...KMC
LONG TERM...SL
AVIATION...ARJ
AREA FORECAST DISCUSSION...UPDATED
NWS NORMAN OK
949 PM CST SUN DEC 21 2014
.UPDATE...
THE AREAS OF DRIZZLE TODAY HAVE SHIFTED OUT OF THE FORECAST AREA
AS NO OBSERVATIONS SITES ARE REPORTING DRIZZLE ANY MORE. MAY SEE
SOME REDEVELOPMENT OF DRIZZLE LATER SINCE NAM SHOWS SOME RISING
MOTION AT THE TOP OF THE MOIST LAYER OVERNIGHT... BUT SIGNAL IS
NOT AS STRONG AS IN PREVIOUS DAYS. SIGNAL IS ALSO NOT AS STRONG AS
FOR FOG REDUCING VISIBILITIES TOO MUCH IN MOST AREAS... ALTHOUGH
THE RAP AND HRRR SHOW AN AREA OF FOG TRANSLATING SOUTHEAST ACROSS
WEST CENTRAL AND SOUTHWEST OKLAHOMA EARLY MONDAY MORNING JUST
BEHIND A WIND SHIFT MOVING ACROSS THAT AREA. HAVE EXPANDED THE
AREA THAT MENTIONS FOG TO INCLUDE THIS REGION... BUT OTHERWISE
HAVE CHANGED THE DESCRIPTOR FOR THE FOG/DRIZZLE FROM AREAS TO
PATCHY SINCE THE COVERAGE IS NOT EXPECTED TOO WIDESPREAD.
&&
.PREV DISCUSSION... /ISSUED 532 PM CST SUN DEC 21 2014/
DISCUSSION...
AVIATION DISCUSSION FOR THE 00Z TAFS IS BELOW.
AVIATION...
CONFIDENCE REMAINS LOW THROUGH 18Z...THEN IS HIGH AFTERWARDS.
OVERALL...DID NOT MAKE TOO MANY CHANGES TO THE PREVIOUS TAFS.
ONGOING MVFR AND LOWER CONDITIONS WILL GENERALLY STICK AROUND
UNTIL A SURFACE TROUGH MOVES THROUGH THE AREA. THE LOWEST
CONDITIONS WILL LIKELY BE OVER WESTERN OKLAHOMA 02-08Z...AND
PERHAPS NEAR KOKC...KOUN...AND KPNC 09-15Z. DOUBT CONDITIONS
WILL WORSEN TO AIRPORT MINIMUMS EXCEPT KGAG.
FOR KLAW AND KSPS...THESE SITES HAVE THE LOWEST CONFIDENCE.
IFR OR LOWER CONDITIONS ARE POSSIBLE AT THESE SITES AS WELL
THROUGH 13Z...BUT DID NOT MENTION TO MUCH UNCERTAINTY.
-DZ WILL END NEAR KOKC...KOUN...AND KPNC BY 02Z. A FEW -SHRA MAY
MOVE ACROSS NORTHERN OKLAHOMA 08-16Z...BUT DID NOT MENTION IN TAFS
AS COVERAGE SHOULD BE TOO SPARSE.
A SURFACE TROUGH WILL BRING GUSTY NORTHWEST WINDS AND IMPROVING
CONDITIONS. THIS TROUGH WILL REACH NORTHWESTERN OKLAHOMA AROUND
08Z...KSPS AND KLAW 11-13Z...KOKC AROUND 15Z...AND KPNC AROUND
17Z. ALL SITES ARE EXPECTED TO BECOME VFR BY 18Z.
MBS
PREV DISCUSSION... /ISSUED 256 PM CST SUN DEC 21 2014/
DISCUSSION...
DRIZZLE HAS DEVELOPED THE PAST HOUR OR SO ACROSS CENTRAL PORTIONS
OF OKLAHOMA AND WILL LIKELY CONTINUE WELL INTO THE EVENING BEFORE
SHIFTING TO THE NORTH AND EAST OF CWA. COLD FRONT EXPECTED TO
ENTER NORTHWEST OKLAHOMA LATE TONIGHT AND PROGRESS QUICKLY OVER
THE REGION TOMORROW MORNING. THIS WILL HELP SCOUR OUT THE
PERSISTENT LOW CLOUDS AND FOG...BUT WE WILL HAVE TO DEAL WITH FAIR
AMOUNT OF MID AND HIGH LEVEL CLOUD COVER THROUGH TUESDAY. AS FAR
AS PRECIPITATION ASSOCIATED WITH THE FRONT AND LARGE UPPER TROUGH
THAT WILL SKIRT THE REGION...MOST OF ANY PRECIP WILL BE OVER
NORTHERN TEXAS AND FAR SOUTHERN OKLAHOMA LATE MONDAY INTO EARLY
TUESDAY AS STRONG JET ROUNDS BASE OF TROUGH AND INTERACTS WITH
ELEVATED FRONTAL SURFACE. COLD CORE SIGNAL BEING PROGD TO AFFECT
FAR NORTHWEST OKLAHOMA TUESDAY IN THE FORM OF VERY LIGHT SHOWERS
POSSIBLY MIXED WITH OR CHANGING TO LIGHT SNOW. WE WILL MENTION A
CHANCE OF SPRINKLES OR FLURRIES. WRF MOST AGGRESSIVE WITH THIS
ACTIVITY...AND VERY LIKELY OVERDONE. ECM KEEPS PRECIP UP IN
KANSAS WITH THE GFS IN BETWEEN.
OTHER THAN THE SMALL AREAS OF LIGHT PRECIP...WINDS AND TEMPS WILL
BE THE MAIN SENSIBLE IMPACTS NEXT SEVERAL DAYS...ALONG WITH A
MAJORITY OF THE REGION GETTING TO SEE THE SUN. BREEZY TOMORROW
MAINLY NORTHERN OKLAHOMA BEHIND THE FRONT. COOL WITH STRONG
NORTHWEST WINDS EXPECTED AGAIN TUESDAY...FOLLOWED BY WARMER WITH
GUSTY SOUTHWEST WINDS CHRISTMAS DAY. BACK TO COOLER AND GUSTY
NORTH WINDS FRIDAY. CHANCES FOR APPRECIABLE SUNSHINE WILL INCREASE
WEDNESDAY INTO NEXT WEEKEND.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 42 57 36 45 / 10 10 10 10
HOBART OK 38 58 35 46 / 10 0 10 10
WICHITA FALLS TX 42 62 39 50 / 10 0 20 10
GAGE OK 35 54 31 41 / 10 0 10 10
PONCA CITY OK 42 54 33 44 / 20 10 10 10
DURANT OK 45 60 41 51 / 10 10 20 20
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
99/99
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
929 PM EST SUN DEC 21 2014
.SYNOPSIS...
A MOIST AIR MASS WILL REMAIN ACROSS THE REGION BEFORE A COLD FRONT
CROSSES EAST ON WEDNESDAY. DRY CANADIAN HIGH PRESSURE WILL BUILD IN
THURSDAY AND PERSIST INTO THE WEEKEND.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 920 PM...RAIN IS GRADUALLY FILLING IN ACROSS THE SC MIDLANDS
AND LOWER PIEDMONT AS FORCING IS INCREASING IN RESPONSE TO UPPER AIR
SPEED MAX LIFTING OUT OF THE LOWER MISS VALLEY. BASED UPON CURRENT
RADAR/OBSERVATIONAL TRENDS...IT/S BECOMING MORE CLEAR THAT PRECIP
WILL PRIMARILY AFFECT THE EASTERN HALF OF THE FORECAST AREA...AND
POPS HAVE BEEN SCALED BACK TO CHANCE ACROSS MUCH OF THE WESTERN
THIRD OF THE FORECAST AREA. THIS IS GOOD NEWS REGARDING THE
POTENTIAL FOR EASTERN ESCARPMENT/NORTHERN NC MTN FREEZING
PRECIP...AS IT/S APPEARING MORE LIKELY THAT A COOLING EASTERLY
UPSLOPE FLOW WILL MAKE IT DIFFICULT TO DISLODGE THE SUB-FREEZING
TEMPS WHERE THEY CURRENTLY EXIST. WE STILL CANNOT RULE OUT SOME
-FZRA OR FZDZ...ESPECIALLY ACROSS AVERY COUNTY...SO THE SPECIAL
WEATHER STATEMENT WILL STAND AS IS. OTHERWISE...THE 00Z NAM HAS
PICKED UP ON THE DRIER TREND SUGGESTED BY THE LATEST OBSERVATIONAL
DATA...SO QPF HAS BEEN LOWERED IN ALL AREAS THROUGH THE NIGHT...AS
EVEN AREAS THAT MEASURE WILL LIKELY SEE AROUND A TENTH OF AN INCH
OR LESS.
AS OF 650 PM...-RA HAS BEEN A BIT SLOWER TO MATERIALIZE THAN
PREVIOUSLY ANTICIPATED...BUT IS BEGINNING TO GRADUALLY FILL IN
ACROSS THE LOWER SC PIEDMONT/MIDLANDS AND SRN/CTRL GA. POPS HAVE
BEEN MAINTAINED AT PREVIOUS LEVELS (CATEGORICAL ACROSS THE SOUTHEAST
THIRD...TAPERING TO CHANCE ALONG THE TENN BORDER)...BUT THE ONSET
HAS BEEN DELAYED A COUPLE OF HOURS. OTHERWISE...THE MAIN CONCERN
WILL REVOLVE AROUND THE POTENTIAL FOR -FZRA OR -FZDZ ACROSS THE
NORTHERN MTNS LATER TONIGHT. IT APPEARS THE PRIMARY PROBLEM AREA
WILL ESSENTIALLY BE AVERY COUNTY...WHERE POCKETS OF FREEZING TEMPS
ARE CURRENTLY OBSERVED...AND AN INCREASING EASTERLY UPSLOPE FLOW
WILL LIKELY PROVIDE ENOUGH OF A COOLING MECHANISM TO MAKE IT
DIFFICULT TO DISLODGE THAT COOL AIR OVERNIGHT. THE AREA OF FREEZING
RAIN HAS BEEN INCREASED IN THE GRIDS. HOWEVER...QPF WILL STILL BE
PROBLEMATIC...AS IT/S NO SLAM DUNK THAT THESE AREAS WILL EVEN SEE
MEASURABLE PRECIP. THEREFORE...DO NOT PLAN TO HOIST ANY ADVISORY
ATTM...BUT WILL ISSUE AN SPS TO MENTION THE POTENTIAL FOR A VERY
LIGHT GLAZE...PRIMARILY ON ELEVATED SURFACES.
AS OF 230 PM...THE STRATUS DECK CONTINUES TO ERODE SLOWLY ACRS THE
MTNS AND LOWER PIEDMONT THIS AFTN...RESULTING IN SLIGHTLY WARMER
TEMPS UNDER MORE SUNSHINE. MOST THE AREA IS STILL OVERCAST OR MOSTLY
CLOUDY...WITH TEMPS IN THE 40S TO LWR 50S.
GUIDANCE IN GOOD AGREEMENT ON A DIGGING TROF TO THE WEST AND A
BUILDING RIDGE ALONG THE EAST COAST TONIGHT THRU MONDAY. SHORTWAVE
ENERGY WILL RIDE FROM SW TO NE THRU THE FLOW ATOP THE SOUTHEAST
STATES...INDUCING A WEAK WAVE ALONG A COASTAL FRONT OFF THE SC COAST
ON MONDAY. INCREASING SOUTHERLY UPGLIDE AND 850 MB WAA FLOW ATOP THE
CWFA. POPS QUICKLY RAMP UP TO CATEGORICAL ACRS THE SOUTHERN HALF OF
THE CWFA...AND LIKELY TO THE NORTH BY LATE EVENING. THE COVERAGE
WILL BE AIDED BY SOME DEEP LAYER Q-VECTOR CONVERGENCE WITHIN THE
SWLY MID-UPR FLOW. HOWEVER...THE MOISTURE DEPTH WILL BE FAIRLY
SHALLOW...AND FORCING OVERALL WEAK. SO QPF AMOUNTS SHUD BE GENERALLY
A FEW HUNDREDTHS TO A TENTH OF AN INCH. ALTHO...A TENTH TO QUARTER
INCH POSSIBLE AROUND THE CHARLOTTE METRO AREA. ONE THING TO MENTION
IS THAT THERMAL PROFILES ARE MARGINAL FOR SOME FREEZING RAIN AND
SLEET ACRS THE NRN MTNS...MAINLY AVERY COUNTY. THE 12Z NAM AND
LATEST RAP KEEP THINGS JUST ABOVE FREEZING. I WOULDN/T BE SURPRISED
IF A FEW SPOTS NEAR THE EASTERLY UPSLOPE AREAS IN AVERY/CALDWELL MAY
HAVE BRIEF FZRA/DZ TOWARD DAYBREAK MONDAY. HOWEVER...CONFIDENCE IS
JUST NOT HIGH ENUF TO ISSUE A FREEZING RAIN ADVISORY AT THIS TIME.
IF THE 18Z NAM COMES IN COLDER...OR IF TRENDS SEEM TO WARRANT
IT...THE EVENING SHIFT MAY WANT TO ISSUE ONE OR AN SPS.
OTHERWISE...IT SHUD BE JUST A COLD RAIN WITH TEMPS IN THE 30S TO LWR
40S.
ON MONDAY...THE MID LVLS DRY OUT...AND THE BETTER FORCING EXITS TO
THE EAST. HOWEVER...A WEDGE IS EXPECTED TO REMAIN...WITH LLVL
UPGLIDE CONTINUING WITHIN SWLY FLOW. THIS LOOKS LIKE A GOOD SETUP
FOR AREAS OF -DZ PERSISTING...ALSO KEEPING TEMPS DOWN. GOING CLOSE
TO THE RAW MODEL TEMPS FOR HIGHS...AND KEEPING A CHC OF -RA AND DZ
THRU THE DAY. HIGHS WILL LIKELY STRUGGLE TO GET INTO THE 40S ACRS
THE I-40 CORRIDOR...AND ONLY THE MID TO UPR 40S ELSEWHERE.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 230 PM EST SUNDAY...MON NIGHT THROUGH TUESDAY NIGHT...LATEST
12Z MODELS CONTINUE TO INDICATE THAT SURFACE COLD AIR DAMMING WEDGE
WILL CONTINUE ACROSS THE AREA AS 1030MB HIGH WILL REMAIN ANCHORED
OVER THE NE. MEANWHILE...STRONG SSWLY FLOW ALOFT DEVELOPS ACROSS THE
SE BY TUE AS A DEEP UPPER TROUGH MOVES EAST ACROSS THE CENTRAL CONUS
WHILE AN UPPER RIDGE AMPLIFIES OVER THE WESTERN ATLANTIC. THIS WILL
LEAD TO INCREASING 290K ISENTROPIC LIFT/ATLANTIC MOISTURE ADVECTION
OVER OUR CWA THRU TUESDAY. HENCE...HAVE CARRIED CHANCE POPS FOR
LIGHT RAIN WITH DRIZZLE MON NIGHT INTO TUE MORNING...RAMPING UP INTO
THE CATEGORICAL POPS WITH STEADY RAIN TOWARDS TUE NIGHT. WITH
ONGOING PRECIP WITHIN THE CAD...AFTERNOON TEMPS ON TUE WILL RUN 7-10
DEGREES BELOW NORMAL OVER THE PIEDMONT WITH 3-5 DEGREES BELOW OVER
THE WESTERN NC MTNS.
WEDNESDAY...THE UPPER TROUGH OVER THE MISSISSIPPI VALLEY WILL
ADVANCE EASTWARD...BECOMING POSITIVELY TILED AS IT PUSHES THROUGH
THE EASTERN CONUS. THIS WILL LIFT A SURFACE LOW INTO THE OHIO VALLEY
BY 18Z...PUSHING ITS ASSOCIATED COLD FRONT THROUGH THE FORECAST AREA
BETWEEN 18Z WED AND 00Z THU. ALTHOUGH THERE WILL BE STRONG LLVL WIND
SHEAR ALONG AND AHEAD OF THE FRONT...THE BEST UPPER FORCING WILL NOT
REACH THE AREA UNTIL 00Z THU AND AREAS SBCAPE REGIME WILL BE SHUNTED
TO THE SOUTH. THEREFORE...HIGH SHEAR LOW CAPE INDUCED SEVERE EVENT
APPEARS UNIMPRESSIVE AT THIS TIME. HAVE INHERITED A CHANCE OF
AFTERNOON THUNDER OVER THE WESTERN NC PIEDMONT...PORTIONS OF THE
UPSTATE SC...NE GEORGIA AND EXTREME WESTERN NC MTN ZONES TO ACCOUNT
FOR THE PRESENCE OF WEAK ELEVATED BUOYANCY. AS FOR QPF...MODELS
STILL DEPICT WIDESPREAD CONVECTIVE ACTIVITY ALONG THE GULF COAST/SE
COAST...WHICH COULD BLOCK DEEP MOISTURE TRANSPORT INTO OUR AREA.
WITH THE UNCERTAINTY...HAVE GONE WITH THE MODEL CONSENSUS
QPF...YIELDING 1-2 INCHES ACROSS THE REGION WITH UP TO 3" OVER THE
BLUE RIDGE ESCARPMENT. CATEGORICAL POPS WERE HIGHLIGHTED THRU 18Z
WED... QUICKLY RAMPING DOWN TO THE CHANCE RANGE FROM WEST TO EAST
THRU 00Z THU AS THE FRONT PUSHES TO THE EAST. WITH INCREASING WAA
FLOW...AFTERNOON TEMPS WILL WARM INTO THE U50S/60S EAST OF THE MTNS
AND 50S OVER THE MTNS.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 200 PM SUNDAY...THE LATE WEEK WILL SEE THE SHARP UPPER TROUGH
PUSH OFF THE EAST COAST...LEAVING QUASI-ZONAL FLOW OVER THE ERN THIRD
OF THE CONUS. DRY HIGH PRESSURE WILL CROSS THE SOUTHEAST BEFORE
HEIGHTS FALL OVER THE MISSISSIPPI VALLEY AS NEXT LOW ROLLS OFF THE
ROCKIES AND ACRS THE GREAT LAKES. DIFFERENCES BETWEEN THE GFS AND EC
ARE MINOR IN TERMS OF SENSIBLE WX CHRISTMAS DAY AND FRIDAY...BOTH
INDICATING NW FLOW PRECIP TAPERING OFF CHRISTMAS MRNG FOLLOWED BY DRY
WX MOST OF FRIDAY. IN COLD ADVECTIVE PATTERN HIGHER ELEVATIONS WILL
LIKELY SEE BREEZY/GUSTY CONDITIONS ON CHRISTMAS. THE COLD FRONT
ASSOCIATED WITH THE GRT LAKES LOW WILL ARRIVE BY FRIDAY NIGHT ALBEIT
WITHOUT MUCH OOMPH...THE GFS PRETTY MUCH WASHING THE FRONT OUT OVER
THE CAROLINAS. THE EC HOWEVER DIVERGES AT THIS POINT...STALLING THE
FRONT ALONG THE COAST AND EVENTUALLY DEVELOPING A COASTAL LOW NEAR
THE OUTER BANKS SUNDAY IN RESPONSE TO A SRN STREAM SHORTWAVE TRAILING
THE FRONT. BOTH THE 21/00Z AND 21/12Z RUNS FEATURE THIS EVOLUTION. SO
WHILE THE GFS WOULD SUGGEST NEXT WEEKEND WILL BE QUIET AND DRY...EC
INDICATES SOME PTYPE ISSUES MAY EXIST SUNDAY WITH WINTRY PARTIAL
THICKNESSES AND THERMAL PROFILES. TEMPS WILL BE AT OR A LITTLE ABOVE
CLIMO FROM THU-SAT...AND BELOW NORMAL SUNDAY IF THE CLOUDS/PRECIP
MATERIALIZE.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
AT KCLT...INCREASING LIFT THROUGH A DEEP LAYER OF THE ATMOSPHERE IS
RESULTING IN SLOWLY INCREASING COVERAGE OF -RA ACROSS THE SC
PIEDMONT/MIDLANDS AND CENTRAL GA...WHICH WILL CONTINUE TO EXPAND AS
IT LIFTS NE THROUGH THE NIGHT. -RA AND MVFR CHANCES WILL INCREASE BY
THE END OF THE EVENING...WITH -RA AND/OR -DZ CONTINUING THROUGH MUCH
OF THE MORNING HOURS. FLT CATEGORY WILL GRADUALLY LOWER TO IFR
DURING THE PRE-DAWN HOURS. ONCE THIS OCCURS...CONDITIONS WILL BE
SLOW TO IMPROVE...AS COOL AIR WEDGE IS EXPECTED TO REMAIN LOCKED IN
NEAR THE SURFACE THROUGH MUCH OF THE PERIOD. WINDS SHOULD REMAIN NE
AT 5-10 KTS THROUGH THE PERIOD.
ELSEWHERE...MVFR CONDITIONS CONTINUE AT MOST TERMINALS THIS
EVENING...AND THIS IS LIKELY AS HIGH AS CIGS WILL BE OVER THE NEXT
24 HOURS. INCREASING LIFT THROUGH A DEEP LAYER OF THE ATMOSPHERE IS
RESULTING IN SLOWLY INCREASING COVERAGE OF -RA ACROSS THE SC
PIEDMONT/MIDLANDS AND CENTRAL GA...WHICH WILL CONTINUE TO EXPAND AS
IT LIFTS NE THROUGH THE NIGHT. CHANCES FOR IFR CIGS WILL INCREASE
ACROSS THE AREA BY 06Z...AND A TEMPO FOR IFR HAS BEEN INCLUDED AT
ALL TERMINALS AROUND THIS TIME...WITH IFR CIGS EXPECTED TO SETTLE IN
NO LATER THAN 07Z OR 08Z. ONCE THIS OCCURS...CONDITIONS WILL BE SLOW
TO IMPROVE...AS COOL AIR WEDGE IS EXPECTED TO REMAIN LOCKED IN NEAR
THE SURFACE THROUGH MUCH OF THE PERIOD.
OUTLOOK...WITH LOW LEVEL MOISTURE LOCKED IN PLACE...FLT RESTRICTIONS
OF SOME SORT WILL LINGER THROUGH AT LEAST EARLY TUESDAY. A COLD
FRONT WILL APPROACH ON TUESDAY FROM THE WEST AND MOVE THROUGH ON
WED. WIDESPREAD SHOWERS WITH RESTRICTIONS SHOULD ARRIVE TUESDAY
AFTERNOON AND WILL CONTINUE UNTIL THE FRONT CLEARS THE AREA LATE
WEDNESDAY. DRY HIGH PRESSURE WILL RETURN LATE WED.
CONFIDENCE TABLE...
02-08Z 08-14Z 14-20Z 20-00Z
KCLT HIGH 98% LOW 48% MED 63% HIGH 100%
KGSP MED 78% MED 63% MED 72% HIGH 100%
KAVL HIGH 100% HIGH 82% MED 71% HIGH 100%
KHKY MED 79% LOW 55% MED 68% HIGH 100%
KGMU MED 76% MED 71% MED 72% HIGH 100%
KAND MED 61% LOW 44% HIGH 84% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...SBK
NEAR TERM...ARK/JDL
SHORT TERM...JOH
LONG TERM...WIMBERLEY
AVIATION...JDL
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
701 PM EST SUN DEC 21 2014
.SYNOPSIS...
A MOIST AIR MASS WILL REMAIN ACROSS THE REGION BEFORE A COLD FRONT
CROSSES EAST ON WEDNESDAY. DRY CANADIAN HIGH PRESSURE WILL BUILD IN
THURSDAY AND PERSIST INTO THE WEEKEND.
&&
.NEAR TERM /THROUGH MONDAY/...
AS OF 650 PM...-RA HAS BEEN A BIT SLOWER TO MATERIALIZE THAN
PREVIOUSLY ANTICIPATED...BUT IS BEGINNING TO GRADUALLY FILL IN
ACROSS THE LOWER SC PIEDMONT/MIDLANDS AND SRN/CTRL GA. POPS HAVE
BEEN MAINTAINED AT PREVIOUS LEVELS (CATEGORICAL ACROSS THE SOUTHEAST
THIRD...TAPERING TO CHANCE ALONG THE TENN BORDER)...BUT THE ONSET
HAS BEEN DELAYED A COUPLE OF HOURS. OTHERWISE...THE MAIN CONCERN
WILL REVOLVE AROUND THE POTENTIAL FOR -FZRA OR -FZDZ ACROSS THE
NORTHERN MTNS LATER TONIGHT. IT APPEARS THE PRIMARY PROBLEM AREA
WILL ESSENTIALLY BE AVERY COUNTY...WHERE POCKETS OF FREEZING TEMPS
ARE CURRENTLY OBSERVED...AND AN INCREASING EASTERLY UPSLOPE FLOW
WILL LIKELY PROVIDE ENOUGH OF A COOLING MECHANISM TO MAKE IT
DIFFICULT TO DISLODGE THAT COOL AIR OVERNIGHT. THE AREA OF FREEZING
RAIN HAS BEEN INCREASED IN THE GRIDS. HOWEVER...QPF WILL STILL BE
PROBLEMATIC...AS IT/S NO SLAM DUNK THAT THESE AREAS WILL EVEN SEE
MEASURABLE PRECIP. THEREFORE...DO NOT PLAN TO HOIST ANY ADVISORY
ATTM...BUT WILL ISSUE AN SPS TO MENTION THE POTENTIAL FOR A VERY
LIGHT GLAZE...PRIMARILY ON ELEVATED SURFACES.
AS OF 230 PM...THE STRATUS DECK CONTINUES TO ERODE SLOWLY ACRS THE
MTNS AND LOWER PIEDMONT THIS AFTN...RESULTING IN SLIGHTLY WARMER
TEMPS UNDER MORE SUNSHINE. MOST THE AREA IS STILL OVERCAST OR MOSTLY
CLOUDY...WITH TEMPS IN THE 40S TO LWR 50S.
GUIDANCE IN GOOD AGREEMENT ON A DIGGING TROF TO THE WEST AND A
BUILDING RIDGE ALONG THE EAST COAST TONIGHT THRU MONDAY. SHORTWAVE
ENERGY WILL RIDE FROM SW TO NE THRU THE FLOW ATOP THE SOUTHEAST
STATES...INDUCING A WEAK WAVE ALONG A COASTAL FRONT OFF THE SC COAST
ON MONDAY. INCREASING SOUTHERLY UPGLIDE AND 850 MB WAA FLOW ATOP THE
CWFA. POPS QUICKLY RAMP UP TO CATEGORICAL ACRS THE SOUTHERN HALF OF
THE CWFA...AND LIKELY TO THE NORTH BY LATE EVENING. THE COVERAGE
WILL BE AIDED BY SOME DEEP LAYER Q-VECTOR CONVERGENCE WITHIN THE
SWLY MID-UPR FLOW. HOWEVER...THE MOISTURE DEPTH WILL BE FAIRLY
SHALLOW...AND FORCING OVERALL WEAK. SO QPF AMOUNTS SHUD BE GENERALLY
A FEW HUNDREDTHS TO A TENTH OF AN INCH. ALTHO...A TENTH TO QUARTER
INCH POSSIBLE AROUND THE CHARLOTTE METRO AREA. ONE THING TO MENTION
IS THAT THERMAL PROFILES ARE MARGINAL FOR SOME FREEZING RAIN AND
SLEET ACRS THE NRN MTNS...MAINLY AVERY COUNTY. THE 12Z NAM AND
LATEST RAP KEEP THINGS JUST ABOVE FREEZING. I WOULDN/T BE SURPRISED
IF A FEW SPOTS NEAR THE EASTERLY UPSLOPE AREAS IN AVERY/CALDWELL MAY
HAVE BRIEF FZRA/DZ TOWARD DAYBREAK MONDAY. HOWEVER...CONFIDENCE IS
JUST NOT HIGH ENUF TO ISSUE A FREEZING RAIN ADVISORY AT THIS TIME.
IF THE 18Z NAM COMES IN COLDER...OR IF TRENDS SEEM TO WARRANT
IT...THE EVENING SHIFT MAY WANT TO ISSUE ONE OR AN SPS.
OTHERWISE...IT SHUD BE JUST A COLD RAIN WITH TEMPS IN THE 30S TO LWR
40S.
ON MONDAY...THE MID LVLS DRY OUT...AND THE BETTER FORCING EXITS TO
THE EAST. HOWEVER...A WEDGE IS EXPECTED TO REMAIN...WITH LLVL
UPGLIDE CONTINUING WITHIN SWLY FLOW. THIS LOOKS LIKE A GOOD SETUP
FOR AREAS OF -DZ PERSISTING...ALSO KEEPING TEMPS DOWN. GOING CLOSE
TO THE RAW MODEL TEMPS FOR HIGHS...AND KEEPING A CHC OF -RA AND DZ
THRU THE DAY. HIGHS WILL LIKELY STRUGGLE TO GET INTO THE 40S ACRS
THE I-40 CORRIDOR...AND ONLY THE MID TO UPR 40S ELSEWHERE.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 230 PM EST SUNDAY...MON NIGHT THROUGH TUESDAY NIGHT...LATEST
12Z MODELS CONTINUE TO INDICATE THAT SURFACE COLD AIR DAMMING WEDGE
WILL CONTINUE ACROSS THE AREA AS 1030MB HIGH WILL REMAIN ANCHORED
OVER THE NE. MEANWHILE...STRONG SSWLY FLOW ALOFT DEVELOPS ACROSS THE
SE BY TUE AS A DEEP UPPER TROUGH MOVES EAST ACROSS THE CENTRAL CONUS
WHILE AN UPPER RIDGE AMPLIFIES OVER THE WESTERN ATLANTIC. THIS WILL
LEAD TO INCREASING 290K ISENTROPIC LIFT/ATLANTIC MOISTURE ADVECTION
OVER OUR CWA THRU TUESDAY. HENCE...HAVE CARRIED CHANCE POPS FOR
LIGHT RAIN WITH DRIZZLE MON NIGHT INTO TUE MORNING...RAMPING UP INTO
THE CATEGORICAL POPS WITH STEADY RAIN TOWARDS TUE NIGHT. WITH
ONGOING PRECIP WITHIN THE CAD...AFTERNOON TEMPS ON TUE WILL RUN 7-10
DEGREES BELOW NORMAL OVER THE PIEDMONT WITH 3-5 DEGREES BELOW OVER
THE WESTERN NC MTNS.
WEDNESDAY...THE UPPER TROUGH OVER THE MISSISSIPPI VALLEY WILL
ADVANCE EASTWARD...BECOMING POSITIVELY TILED AS IT PUSHES THROUGH
THE EASTERN CONUS. THIS WILL LIFT A SURFACE LOW INTO THE OHIO VALLEY
BY 18Z...PUSHING ITS ASSOCIATED COLD FRONT THROUGH THE FORECAST AREA
BETWEEN 18Z WED AND 00Z THU. ALTHOUGH THERE WILL BE STRONG LLVL WIND
SHEAR ALONG AND AHEAD OF THE FRONT...THE BEST UPPER FORCING WILL NOT
REACH THE AREA UNTIL 00Z THU AND AREAS SBCAPE REGIME WILL BE SHUNTED
TO THE SOUTH. THEREFORE...HIGH SHEAR LOW CAPE INDUCED SEVERE EVENT
APPEARS UNIMPRESSIVE AT THIS TIME. HAVE INHERITED A CHANCE OF
AFTERNOON THUNDER OVER THE WESTERN NC PIEDMONT...PORTIONS OF THE
UPSTATE SC...NE GEORGIA AND EXTREME WESTERN NC MTN ZONES TO ACCOUNT
FOR THE PRESENCE OF WEAK ELEVATED BUOYANCY. AS FOR QPF...MODELS
STILL DEPICT WIDESPREAD CONVECTIVE ACTIVITY ALONG THE GULF COAST/SE
COAST...WHICH COULD BLOCK DEEP MOISTURE TRANSPORT INTO OUR AREA.
WITH THE UNCERTAINTY...HAVE GONE WITH THE MODEL CONSENSUS
QPF...YIELDING 1-2 INCHES ACROSS THE REGION WITH UP TO 3" OVER THE
BLUE RIDGE ESCARPMENT. CATEGORICAL POPS WERE HIGHLIGHTED THRU 18Z
WED... QUICKLY RAMPING DOWN TO THE CHANCE RANGE FROM WEST TO EAST
THRU 00Z THU AS THE FRONT PUSHES TO THE EAST. WITH INCREASING WAA
FLOW...AFTERNOON TEMPS WILL WARM INTO THE U50S/60S EAST OF THE MTNS
AND 50S OVER THE MTNS.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 200 PM SUNDAY...THE LATE WEEK WILL SEE THE SHARP UPPER TROUGH
PUSH OFF THE EAST COAST...LEAVING QUASI-ZONAL FLOW OVER THE ERN THIRD
OF THE CONUS. DRY HIGH PRESSURE WILL CROSS THE SOUTHEAST BEFORE
HEIGHTS FALL OVER THE MISSISSIPPI VALLEY AS NEXT LOW ROLLS OFF THE
ROCKIES AND ACRS THE GREAT LAKES. DIFFERENCES BETWEEN THE GFS AND EC
ARE MINOR IN TERMS OF SENSIBLE WX CHRISTMAS DAY AND FRIDAY...BOTH
INDICATING NW FLOW PRECIP TAPERING OFF CHRISTMAS MRNG FOLLOWED BY DRY
WX MOST OF FRIDAY. IN COLD ADVECTIVE PATTERN HIGHER ELEVATIONS WILL
LIKELY SEE BREEZY/GUSTY CONDITIONS ON CHRISTMAS. THE COLD FRONT
ASSOCIATED WITH THE GRT LAKES LOW WILL ARRIVE BY FRIDAY NIGHT ALBEIT
WITHOUT MUCH OOMPH...THE GFS PRETTY MUCH WASHING THE FRONT OUT OVER
THE CAROLINAS. THE EC HOWEVER DIVERGES AT THIS POINT...STALLING THE
FRONT ALONG THE COAST AND EVENTUALLY DEVELOPING A COASTAL LOW NEAR
THE OUTER BANKS SUNDAY IN RESPONSE TO A SRN STREAM SHORTWAVE TRAILING
THE FRONT. BOTH THE 21/00Z AND 21/12Z RUNS FEATURE THIS EVOLUTION. SO
WHILE THE GFS WOULD SUGGEST NEXT WEEKEND WILL BE QUIET AND DRY...EC
INDICATES SOME PTYPE ISSUES MAY EXIST SUNDAY WITH WINTRY PARTIAL
THICKNESSES AND THERMAL PROFILES. TEMPS WILL BE AT OR A LITTLE ABOVE
CLIMO FROM THU-SAT...AND BELOW NORMAL SUNDAY IF THE CLOUDS/PRECIP
MATERIALIZE.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
AT KCLT...INCREASING LIFT THROUGH A DEEP LAYER OF THE ATMOSPHERE IS
RESULTING IN SLOWLY INCREASING COVERAGE OF -RA ACROSS THE SC
PIEDMONT/MIDLANDS AND CENTRAL GA...WHICH WILL CONTINUE TO EXPAND AS
IT LIFTS NE THROUGH THE NIGHT. -RA AND MVFR CHANCES WILL INCREASE BY
THE END OF THE EVENING...WITH -RA AND/OR -DZ CONTINUING THROUGH MUCH
OF THE MORNING HOURS. FLT CATEGORY WILL GRADUALLY LOWER TO IFR
DURING THE PRE-DAWN HOURS. ONCE THIS OCCURS...CONDITIONS WILL BE
SLOW TO IMPROVE...AS COOL AIR WEDGE IS EXPECTED TO REMAIN LOCKED IN
NEAR THE SURFACE THROUGH MUCH OF THE PERIOD. WINDS SHOULD REMAIN NE
AT 5-10 KTS THROUGH THE PERIOD.
ELSEWHERE...MVFR CONDITIONS CONTINUE AT MOST TERMINALS THIS
EVENING...AND THIS IS LIKELY AS HIGH AS CIGS WILL BE OVER THE NEXT
24 HOURS. INCREASING LIFT THROUGH A DEEP LAYER OF THE ATMOSPHERE IS
RESULTING IN SLOWLY INCREASING COVERAGE OF -RA ACROSS THE SC
PIEDMONT/MIDLANDS AND CENTRAL GA...WHICH WILL CONTINUE TO EXPAND AS
IT LIFTS NE THROUGH THE NIGHT. CHANCES FOR IFR CIGS WILL INCREASE
ACROSS THE AREA BY 06Z...AND A TEMPO FOR IFR HAS BEEN INCLUDED AT
ALL TERMINALS AROUND THIS TIME...WITH IFR CIGS EXPECTED TO SETTLE IN
NO LATER THAN 07Z OR 08Z. ONCE THIS OCCURS...CONDITIONS WILL BE SLOW
TO IMPROVE...AS COOL AIR WEDGE IS EXPECTED TO REMAIN LOCKED IN NEAR
THE SURFACE THROUGH MUCH OF THE PERIOD.
OUTLOOK...WITH LOW LEVEL MOISTURE LOCKED IN PLACE...FLT RESTRICTIONS
OF SOME SORT WILL LINGER THROUGH AT LEAST EARLY TUESDAY. A COLD
FRONT WILL APPROACH ON TUESDAY FROM THE WEST AND MOVE THROUGH ON
WED. WIDESPREAD SHOWERS WITH RESTRICTIONS SHOULD ARRIVE TUESDAY
AFTERNOON AND WILL CONTINUE UNTIL THE FRONT CLEARS THE AREA LATE
WEDNESDAY. DRY HIGH PRESSURE WILL RETURN LATE WED.
CONFIDENCE TABLE...
00-06Z 06-12Z 12-18Z 18-00Z
KCLT HIGH 97% MED 68% MED 69% HIGH 96%
KGSP HIGH 80% HIGH 84% MED 75% HIGH 96%
KAVL HIGH 96% MED 71% MED 68% HIGH 100%
KHKY HIGH 80% LOW 53% MED 61% HIGH 96%
KGMU HIGH 80% HIGH 84% MED 75% HIGH 96%
KAND MED 72% MED 71% MED 75% HIGH 96%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)
WWW.WEATHER.GOV/GSP/AVIATION_TABLES
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...SBK
NEAR TERM...ARK/JDL
SHORT TERM...JOH
LONG TERM...WIMBERLEY
AVIATION...JDL
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
548 PM CST SUN DEC 21 2014
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 323 PM CST SUN DEC 21 2014
CLEARING LINE HAS MADE SOME PROGRESS EAST THIS AFTERNOON. HOWEVER BY
LATE THIS AFTERNOON AND EVENING EXPECT THE LOW STRATUS TO RETURN
NORTHWEST AND COVER MUCH OF THE AREA YET AGAIN. HRRR AND RAP
GUIDANCE HAVE BEEN DOING PRETTY WELL THE PAST FEW NIGHTS...AND
SUGGEST DENSE FOG WILL PROBABLY NOT BE AS BIG OF AN ISSUE TONIGHT. A
STRONG UPPER WAVE WILL DIVE SOUTHEAST INTO THE PLAINS TONIGHT. STILL
QUITE THE SPREAD AMONG MODEL SOLUTIONS. NAM AND GFS ARE FURTHER
SOUTH WITH THE SYSTEM THAN THE ECMWF. ECMWF HAS BEEN THE MOST
CONSISTENT AND THE PARALLEL UPGRADED GFS IS MORE IN LINE WITH THE
ECMWF SOLUTION. THUS DECIDED TO WEIGH HEAVILY IN THAT DIRECTION FOR
THIS FORECAST. LIFT AHEAD OF THE WAVE WILL LIKELY GENERATE
PRECIPITATION TONIGHT...DEVELOPING IN THE WEST THIS EVENING...AND
SPREADING EAST THROUGH THE NIGHT. BASED ON MODEL SOUNDINGS AND
CONSENSUS RAW TEMPERATURES...BELIEVE THIS WILL MAINLY BE RAIN.
ALTHOUGH COULD SEE SOME SLEET MIXED IN...MAINLY WEST OF THE JAMES
RIVER.
MONDAY IS WHEN THE MODEL DIFFERENCES BEGIN TO HAVE A BIGGER IMPACT
ON THE FORECAST. THE FAVORED ECMWF AND PARALLEL GFS SOLUTION RESULTS
IN A DRY SLOT OVER MUCH OF THE CWA. THE MAJORITY OF THE WRAP AROUND
SNOW ASSOCIATED WITH THE DEVELOPING TROWAL SHOULD STAY NORTHWEST OF
THE CWA. DO THINK LOCATIONS FROM HURON TO CHAMBERLAIN COULD GET IN
ON SOME OF THIS ACTIVITY THOUGH. SOUNDINGS SUGGEST THAT BY MONDAY
ANY WARM LAYER IS SURFACE BASED...SUGGESTING EITHER RAIN OR SNOW
DEPENDING ON SURFACE TEMPERATURE. RAW MODEL CONSENSUS OF
TEMPERATURES SUGGESTS PTYPE STAYS PREDOMINATELY RAIN EAST OF THE
JAMES RIVER INTO THE AFTERNOON...WITH THE RAIN SNOW MIX GETTING TO
INTERSTATE 29 BY 0Z. BUT AS MENTIONED...MUCH OF THE CWA SHOULD SEE
VERY LIMITED QPF THROUGH THE DAY HOURS...WITH JUST SOME RAIN IN THE
FAR EAST AND AN INCH OR TWO OF SNOW FROM BRULE TO WESTERN BEADLE
COUNTY. WILL NEED TO MONITOR MODEL TRENDS...BECAUSE IF THE NAM AND
OPERATIONAL GFS FURTHER SOUTH SOLUTION VERIFIES...MORE OF THE CWA
WOULD SEE PRECIP ON MONDAY. BUT EVEN THEN THE WARM LOW LEVEL
TEMPERATURES WOULD LIKELY KEEP MOST AREAS RAIN FOR A MAJORITY OF THE
DAY KEEPING ANY SNOW ACCUMS DOWN.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 323 PM CST SUN DEC 21 2014
MONDAY NIGHT INTO TUESDAY WILL BE A PERIOD WHERE THE SYSTEM HAS
SLOWED DOWN JUST A BIT AND A FAIRLY PERSISTENT TROWAL SETS UP.
STRONG NORTH TO NORTHWEST WINDS WILL GRADUALLY DEVELOP THROUGH THE
DAY SO IT IS STARTING TO LOOK LIKE WE MAY NEED AND ADVISORY FOR SNOW
AND BLOWING SNOW MONDAY NIGHT INTO TUESDAY. MODELS STILL HAVE JUST
ENOUGH DISAGREEMENT AND THE WORST CONDITIONS LOOK TO BE LATE THIRD
PERIOD INTO 4TH PERIOD SO WILL HOLD OFF ON ISSUING ANY HEADLINES BUT
IF THIS EVENINGS MODELS COME IN SIMILAR WILL LIKELY NEED SOMETHING.
MONDAY EVENING WILL START OFF RELATIVELY MILD IN THE SOUTHEAST WITH
TEMPERATURES ABOVE FREEZING SO A BETTER CHANCE FOR RAIN IN NORTHWEST
IOWA BEFORE MIDNIGHT BUT BY ABOUT 11PM TO MIDNIGHT SHOULD BE COLD
ENOUGH FOR SNOW. NO CONCERNS RIGHT NOW OF MIXED PRECIPITATION MONDAY
NIGHT AS THE WARM LAYER IS AT THE GROUND SO SHOULD BE EITHER RAIN OR
SNOW. WENT AHEAD AND INCREASED POPS TONIGHT INTO TUESDAY AND
INCREASED QPF AMOUNTS SOME SO THAT BY TUESDAY EVENING SO THAT MUCH
OF THE AREA SHOULD SEE 2 TO 4 INCHES WITH THE JAMES VALLEY WEST
SEEING THE BEST CHANCE AT APPROACHING 4 INCHES. AGAIN...WITH 2 TO 4
INCHES OF SNOW AND 20 TO 35 MPH WINDS ON TUESDAY AND TUESDAY NIGHT
HAZARDOUS TRAVEL IS LOOKING MORE LIKELY TUESDAY INTO WEDNESDAY.
BY WEDNESDAY EVERYTHING SHOULD BE TO THE EAST OF THE AREA AND WINDS
WILL DIMINISH THROUGH THE DAY. CLOUD COVER SHOULD ALSO BREAK UP A
BIT...AT LEAST GETTING DOWN TO MOSTLY CLOUDY. WITH FRESH SNOW ON THE
GROUND EXPECTING HIGHS MAINLY IN THE 20S.
IN THE OUTER PERIODS (THURSDAY THROUGH SUNDAY)...STILL AN
INTERESTING SYSTEM COMING THROUGH ON THURSDAY NIGHT INTO FRIDAY. THE
12Z GFS SEEMED A BIT OUT TO LUNCH BUT THE 12Z ECMWF AND THE 12Z
PARALLEL GFS BOTH AGREED WELL AND SHOWED SOME CONSISTENCY FROM
YESTERDAYS RUNS. UNFORTUNATELY THE SUPERBLEND IS POLLUTED WITH THE
12Z GFS SO POPS CAME IN MUCH LOWER. HAVING TROUBLE COLLABORATING
HIGHER POPS BUT RIGHT NOW ANTICIPATE THAT POPS WILL NEED TO BE
INCREASED FOR ESPECIALLY THURSDAY NIGHT. AFTER THIS STARTING TO LOOK
LIKE A PERIOD OF COLDER WEATHER WILL SETTLE IN AS A LARGE SCALE
TROUGH SETS UP NORTHERLY FLOW ALOFT INTO THE NORTHERN ROCKIES AND
NORTHERN PLAINS. SO ANTICIPATING HIGHS IN THE TEENS AND 20S FRIDAY
INTO SUNDAY WITH LOWS IN THE SINGLE DIGITS...POSSIBLY DIPPING BELOW
ZERO ASSUMING PARALLEL AND ECMWF ARE MORE ON TARGET. SO WENT AHEAD
AND DROPPED SUPERBLEND LOWS ABOUT 2 TO 4 DEGREES IN MOST LOCATIONS
SATURDAY MORNING AND SUNDAY MORNING.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 548 PM CST SUN DEC 21 2014
IFR TO LIFR CIGS WILL PERSIST ALONG/EAST OF THE JAMES RIVER...WITH
STRATUS BACKING INTO KHON AT THE START OF THE PERIOD. WILL SEE RAIN
DEVELOP LATER TONIGHT...POSSIBLY MIXED WITH SOME SLEET OVER FAR
WESTERN/NORTHERN PORTIONS OF THE FORECAST AREA...INCLUDING KHON TAF
LOCATION TOWARD DAYBREAK. CIGS COULD BUMP UP INTO IFR OR LOW END
MVFR AS RAIN STARTS...BUT CONFIDENCE IN THIS IS LOW AND WILL
STICK WITH IFR-LIFR PERSISTENCE WITH GENERALLY MVFR-IFR VISIBILITY.
RAIN WILL SLOWLY TRANSITION TO SNOW NEAR/WEST OF THE JAMES RIVER BY
18Z. FARTHER EAST THE TRANSITION MAY BE MORE ELEVATION DEPENDENT
THROUGH THE AFTERNOON...WITH HIGHER ELEVATIONS IN EAST CENTRAL SD
AND SOUTHWEST MN TRANSITIONING FIRST...WHILE VALLEYS INCLUDING KFSD
AND KSUX TAF LOCATIONS SEE RAIN THROUGH MOST OF THE TAF PERIOD.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...CHENARD
LONG TERM...08
AVIATION...JH
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
324 PM CST SAT DEC 20 2014
.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
LOW CLOUDS AND FOG WILL ONCE AGAIN BE THE RULE OVERNIGHT AS A VERY
MOIST LOW LEVEL AIR MASS REMAINS IN PLACE. BEEN CLOSELY FOLLOWING
THE HRRR LOW-LEVEL CLOUD COVER PRODUCT WHICH HAS BEEN DOING AN
AMAZING JOB WITH HANDLING STRATUS DECKS THE PAST SEVERAL EVENTS.
IT BASICALLY SHOWS THE STRATUS CLOUDS REMAINING IN PLACE ALL NIGHT
WITH A SLIGHT WESTWARD PUSH ONCE AGAIN ON ITS WESTERN EDGE. WILL
GO WITH PERSISTENCE FORECAST CONCERNING THE FOG AS IT HAS BEEN
OCCURRING THE PAST FEW NIGHTS UNDERNEATH THE STRATUS...SO NO
REASON WHY IT WONT HAPPEN AGAIN...AND IN FACT WIDESPREAD LIGHT FOG
IS ALREADY IN PLACE...WITH LOCALLY THICKER FOG. SEEMS THE MOIST
LAYER IS TOO SHALLOW FOR ANY MEANINGFUL FREEZING DRIZZLE TO OCCUR
OVERNIGHT BUT SOMETHING TO KEEP AN EYE ON ANYWAY.
ON SUNDAY...EXPECTING LOW CLOUDS TO HANG IN TOUGH ACROSS THE EAST
ONCE AGAIN WITH NO REAL SIGNALS FROM ANYTHING TO CLEAR THEM OUT.
WILL ALSO BE WATCHING ARRIVAL OF THE LOW PRESSURE SYSTEM WHICH
WILL ENTER THE DAKOTAS BY SUNDAY EVENING...THEN MOVE INTO WESTERN
MINNESOTA AND IOWA REGION BY MONDAY NIGHT. MODELS STILL HAVING A
TOUGH TIME HANDLING THIS SYSTEM IN REGARDS TO STRENGTH MAINLY.
THEY REALLY DO NOT KNOW HOW TO HANDLE THE EVENTUAL CLOSING OFF AND
SUBSEQUENT MOVEMENT OF THE UPPER LOW...AND ITS ASSOCIATED MOISTURE
AVAILABILITY. THIS WILL BE KEY IN FIGURING OUT JUST HOW MUCH WRAP
AROUND PRECIPITATION WE RECEIVE. BASICALLY TOOK A BLENDED APPROACH
FOR RIGHT NOW WHICH STILL LEAVES THE AREA WITH A COUPLE INCHES OF
SNOW AND SOME MIXED PRECIP IN THE FORM OF FREEZING RAIN AND SLEET
TO START THINGS OFF SUNDAY EVENING. THERMAL PROFILES EVENTUALLY
GET COLD ENOUGH BY MONDAY TO CHANGE THINGS OVER TO SNOW. STILL
HAVE MANY DOUBTS AND LOW CONFIDENCE IN EXACTLY JUST HOW THIS
SYSTEM WILL EVOLVE AND HOW MUCH MOISTURE WILL REALLY BE ASSOCIATED
WITH IT. HAVE A FEELING MODELS MAY NOT LATCH ON TO A MORE
DEFINITIVE SOLUTION UNTIL SOMETIME SUNDAY.
.LONG TERM...TUESDAY THROUGH SATURDAY
LOW PRESSURE WILL BE EAST OF THE REGION WHEN THE PERIOD STARTS
WITH THE POTENTIAL FOR LINGERING SNOW SHOWERS...MAINLY ACROSS THE
EASTERN PART OF THE CWA THROUGH THE DAY TUESDAY. A DECENT PRESSURE
GRADIENT ACROSS THE AREA MAY RESULT IN BREEZY TO WINDY CONDITIONS
AS WELL. WEAK HIGH PRESSURE THEN MOVES IN WITH DRY CONDITIONS
EXPECTED WEDNESDAY. ANOTHER LOW PRESSURE SYSTEM LOOKS TO TRACK
ACROSS THE CENTRAL PLAINS ON THURSDAY...BUT THE MODELS ARE NOT IN
VERY GOOD AGREEMENT WITH STRENGTH OR TIMING. THE GFS AND ECMWF
AGREE SOMEWHAT ON THE TIMING WITH THE GEM BEING MUCH SLOWER.
HOWEVER...THE GFS BRINGS LITTLE IN THE WAY OF
PRECIPITATION...WHILE THE ECMWF PLASTERS MOST OF THE STATE, FOR
NOW...WILL STICK FAIRLY CLOSE TO THE SUPERBLEND KEEPING SCHC/CHC
POPS MAINLY ACROSS THE SOUTHERN CWA THURSDAY INTO THE DAY FRIDAY.
HIGH PRESSURE WILL MOVE BACK IN AFTER THAT WITH DRY CONDITIONS
FRIDAY NIGHT THROUGH THE DAY SATURDAY.
SLIGHTLY ABOVE NORMAL TEMPERATURES WILL BE THE RULE FOR THE FIRST
HALF OF THE PERIOD...WITH HIGHS MAINLY IN THE MID 20S TO LOWER 30S
TUESDAY...WEDNESDAY AND THURSDAY. COOLER AIR THEN MOVES IN BEHIND
THE STORM SYSTEM...WITH HIGHS IN THE TEENS AND 20S FRIDAY AND
SATURDAY.
&&
.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
IFR CIGS WILL REMAIN FIRMLY IN PLACE ACROSS THE EASTERN HALF OF
THE CWA THROUGH THE TAF PERIOD. UNDER THE LOW CLOUDS...VSBYS WILL
GENERALLY BE MVFR IN FOG THIS AFTERNOON...BUT THERE WILL LIKELY BE
PERIODS OF IFR VSBYS AGAIN OVERNIGHT AND INTO EARLY SUNDAY
MORNING...AFFECTING KABR AND KATY. VFR CONDITIONS WILL PREVAIL
ACROSS THE WESTERN HALF OF THE CWA WITH JUST SOME HIGH CLOUDS
STREAMING OVERHEAD.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
SHORT TERM...TMT
LONG TERM...PARKIN
AVIATION...PARKIN
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
222 PM CST SAT DEC 20 2014
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 221 PM CST SAT DEC 20 2014
MUCH OF THE SAME EXPECTED TONIGHT INTO TOMORROW WITH THE LOW
CLOUDS HANGING TOUGH OVER A MAJORITY OF THE AREA. DO NOT REALLY
EXPECT THE CLEARING LINE TO MOVE MUCH THROUGH TOMORROW...WITH ONLY
GREGORY...BRULE AND PORTIONS OF CHARLES MIX COUNTIES SEEING ANY
CLEARING AND SUN. SIGNAL THAT THE DENSER FOG MAY ENCOMPASS MORE OF
THE AREA TONIGHT...MAKING IT TO AROUND THE INTERSTATE 29 CORRIDOR.
SO WILL HAVE TO KEEP AN EYE ON THIS...FOR NOW INCREASED MENTION OF
FOG IN THE GRIDS. GFS AND RAP SUGGEST LOW LEVEL MOISTURE DEPTH WILL
INCREASE TONIGHT AHEAD OF A WEAK UPPER WAVE THAT CROSSES THE REGION.
THIS HAPPENS MAINLY ACROSS PORTIONS OF NORTHWEST IOWA FROM SIOUX
CITY TO SPENCER. SO COULD POTENTIALLY SEE SOME PATCHY DRIZZLE OR
FREEZING DRIZZLE IN THAT AREA...BUT ANYTHING SHOULD BE LIGHT.
GIVEN THE CLOUD COVER...DIURNAL RANGE OF TEMPERATURES WILL BE SMALL.
WILL NOT FALL MUCH TONIGHT...WITH UPPER 20S TO LOW 30S EXPECTED.
THEN ON SUNDAY WE WILL ONLY WARM UP SEVERAL DEGREES...WITH 30S
ACROSS MOST OF THE REGION. WILL START TO BECOME A BIT BREEZY OUT OF
THE SOUTH BY LATER SUNDAY...WITH GUSTS AROUND 25 MPH EAST OF THE
JAMES RIVER.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 221 PM CST SAT DEC 20 2014
PRECIPITATION LIKELY TO DEVELOP ON SUNDAY...WITH THE BETTER CHANCES
IN THE EASTERN CWA. WHILE THE MAIN WARM FRONT IS TO THE NORTH OF THE
AREA...THE PV ANOMOLY AND COLD FRONT ALOFT SWING THROUGH SUNDAY
NIGHT AND SHOULD ALLOW WHAT WILL BE MAINLY RAIN. THE NORTHERN AND
WESTERN CWA COULD SEE SOME MIXED PRECIPITATION BUT THE CHANCES FOR
PRECIPITATION A LITTLE LOWER IN THESE LOCATIONS SO HOPEFULLY LITTLE
OR NO ACCUMULATION. TEMPERATURES REMAIN PRETTY MILD THROUGH THE
NIGHT AS WELL WITH LOW PRESSURE WRAPPING UP TO THE NORTH AND WEST OF
THE AREA SO MAINLY SOUTHERLY OR WESTERLY FLOW. LOWS GENERALLY FROM
THE LOWER TO MIDDLE 30S.
LOOKS LIKE EVERYONE SHOULD WARM TO AT LEAST THE MID 30S ON MONDAY
WITH LOWER 40S LIKELY IN PARTS OF NORTHWEST IOWA. THE DAYTIME
CHANCES FOR PRECIPITATION SHOULD NOT BE REAL HIGH AND WILL KEEP MOST
LOCATIONS IN THE CHANCE CATEGORY AS THE AREA WAITS FOR THE WRAP
AROUND TO SET UP LATE MONDAY AFTERNOON INTO MONDAY NIGHT. RIGHT NOW
LOOKING LIKE MAINLY A RAIN TO SNOW TRANSITION WITH LITTLE CHANCE FOR
SLEET AND FREEZING RAIN MONDAY AND MONDAY NIGHT.
THE CHANCE FOR SNOW WILL LINGER INTO TUESDAY BUT AMOUNTS WILL REMAIN
FAIRLY MINIMAL. WHEN ALL IS SAID AND DONE LOOKING AT ABOUT A HALF AN
INCH TO AN INCH OVER NORTHWEST IOWA TO 2 TO 3 INCHES FROM HURON TO
MARSHALL. A WAVE TRACKS THROUGH TO THE NORTH OF THE AREA ON TUESDAY
WHICH WILL BRING SOME DRYING ALOFT AND BRING AN END TO THE THREAT
FOR PRECIPITATION TUESDAY NIGHT INTO WEDNESDAY.
THE UPPER LEVEL PATTERN REMAINS FAIRLY ACTIVE THROUGH THE EXTENDED
PERIOD WITH ONE WAVE EXITING ON WEDNESDAY AND ANOTHER MOVING INTO
THE AREA FRIDAY INTO SATURDAY. STILL SOME DECENT DIFFERENCES FOR THE
INCOMING SYSTEM SO NOT OVERLY CONFIDENT ON WHAT TO EXPECT BUT RIGHT
NOW LOOKS COLD ENOUGH FOR ALL SNOW...JUST A MATTER OF WHETHER OR NOT
THIS IS A SYSTEM THAT MOVES THROUGH RATHER QUICKLY OR ONE THAT TAKES
ON JUST A TOUCH OF NEGATIVE TILT LIKE THE ECMWF SUGGESTS AND BRINGS
IN A BETTER CHANCE FOR HEAVIER AMOUNTS. UNFORTUNATELY NO WAY TO
REALLY FIGURE THIS OUT RIGHT NOW SO WILL CONTINUE TO CARRY A CHANCE
OF SNOW THURSDAY NIGHT INTO SATURDAY. FOR NOW WEDNESDAY AND THURSDAY
LOOK MAINLY DRY WITH SLIGHTLY BELOW NORMAL HIGH TEMPERATURES THROUGH
THE PERIOD. OVERNIGHT LOWS WILL LIKELY BE AT OR ABOVE NORMAL DURING
THIS TIME.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1117 AM CST SAT DEC 20 2014
POOR AVIATION CONDITIONS WILL CONTINUE THROUGH THE PERIOD...WITH
IFR TO LIFR CIGS AND VIS LIKELY. NOT REALLY EXPECTING MUCH CHANGE
FROM THE CURRENT CONDITIONS...SO MAINLY WENT WITH A PERSISTENCE
FORECAST. SOME SIGNS THAT DENSER FOG AND LIFR CIGS WILL SPREAD A
BIT FURTHER EAST TONIGHT TOWARDS INTERSTATE 29 TONIGHT.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...CHENARD
LONG TERM...08
AVIATION...CHENARD
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
322 PM EST SAT DEC 20 2014
.SHORT TERM...(TONIGHT THROUGH MONDAY)...CLOUDS ARE SLOWLY ERODING
FROM THE WEST THIS AFTERNOON...AND MOST OF THE TN VALLEY SHOULD BE
CLEAR BEFORE MIDNIGHT IF THE TREND CONTINUES AND IF THE HRRR IS
ACCURATE. WITH THE EXPECTED CLEARING AND CALM WINDS...CONDITIONS
APPEAR FAVORABLE FOR FOG TONIGHT. CROSSOVER TEMPERATURES ARE
ESPECIALLY FAVORABLE NORTH...SO WILL MENTION PATCHY/AREAS OF FOG
THERE AS WELL AS SW NC. FOG SHOULD BE SLOW TO DISSIPATE DUE TO THE
LOW SUN ANGLE AND WEAK MIXING TOMORROW MORNING. THE REST OF THE DAY
SHOULD BE MOSTLY SUNNY...WITH HIGH CLOUDS INCREASING LATE IN THE
DAY.
A WEAK SHORTWAVE TROUGH IN THE SOUTHERN STREAM NOW OVER TX WILL BE
LIFTING E-NE AND CROSSING OUR AREA SUNDAY NIGHT AND MONDAY. WITH THE
JET POSITIONED FROM SOUTHERN AL TO THE NC COAST...THE MAJORITY OF
LIFT AND DEEP MOISTURE APPEARS TO BE EAST OF OUR AREA. THE NAM
PULLS MORE MOISTURE INTO OUR AREA THAN THE GFS...BUT EVEN THE NAM
SHOWS THIS MOISTURE MAINLY BELOW THE -10C LEVEL...SUGGESTING THAT
DRIZZLE IS MORE LIKELY THAN MEASURABLE RAINFALL. AS A RESULT...WILL
CUT BACK POPS TO A CHANCE EAST TO NOTHING WEST...BUT MENTIONING
DRIZZLE EVERYWHERE. QPF WILL BE REDUCED AS WELL...TO NO MORE THAN A
TENTH IN THE MOUNTAINS. TEMPERATURE PROFILES IN ALL THE MODEL
SOUNDINGS INDICATE ALL LIQUID PRECIP. THE TROUGH PASSAGE SHOULD
BRING AN END TO ANY RAIN/DRIZZLE ON MONDAY AFTERNOON.
.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)...QUITE THE ACTIVE LONG
TERM PERIOD WITH A HIGHLY AMPLIFIED SYSTEM COMING IN FOR CHRISTMAS THAT
WILL BRING...RAIN...MAYBE A FEW STORMS...WIND...AND PERHAPS SNOW.
MONDAY NIGHT INTO TUESDAY HEIGHTS WILL BE QUICKLY BUILDING OUT AHEAD
OF A DEEP TROUGH MOVING ACROSS THE CENTRAL U.S. AND SOUTHERN PLAINS.
THIS WILL ALLOW FOR MONDAY NIGHT AND TUESDAY DAY TO BE UNSEASONABLE
WARM. LOWS MONDAY NIGHT WILL BE 10 TO 12 DEGREES ABOVE NORMAL. HIGHS
ON TUESDAY WILL BE IN THE MID TO UPPER 50S...5 TO 10 DEGREES ABOVE
NORMAL. RAIN CHANCES INCREASE ON TUESDAY AS THIS HIGHLY AMPLIFIED
AND DEEP TROUGH IS ON OUR DOORSTEP BY TUESDAY AFTERNOON. DID DECIDE
TO INTRODUCE SLIGHT CHANCE OF THUNDERSTORMS FROM KNOXVILLE SOUTH
TUESDAY AFTERNOON INTO TUESDAY NIGHT. CAPE IS VERY WEAK BUT SHEAR
AND HELICITY ARE ROBUST...IN LARGE PART DUE TO A STRONG 850MB JET OF
40 TO 50 KTS THAT WILL BE IN PLACE. BETTER INSTABILITY EXISTS
FURTHER TO OUR SOUTH AND SOUTHWEST BUT DID WANT TO MENTION A STORM
OR TWO POSSIBLE ACROSS OUR CENTRAL AND SOUTHERN AREAS. ABUNDANT
MOISTURE AND STRONG LIFT WILL LEAD TO SOME DECENT RAINFALL ACROSS
THE AREA FOR TUESDAY NIGHT INTO WEDNESDAY...MORE SO ACROSS THE
SOUTHERN AREAS. CURRENT GFS SOUNDINGS SHOW PW VALUES RANGING FROM
1.40 TO 1.20 INCHES FROM SOUTH TO NORTH. THIS PUTS US AT 2SD ABOVE
NORMAL FOR THIS TIME OF YEAR. I DON`T THINK FLOODING WILL BE A
CONCERN THOUGH BECAUSE OF HOW QUICKLY THIS SYSTEM IS MOVING. SO NOW
THAT WE HAVE TALKED ABOUT RAIN AND STORMS...LET`S TALK ABOUT SNOW.
CHRISTMAS EVE IS LOOKING TO BE RATHER NASTY WITH THE DEEP TROUGH AND
ASSOCIATED SURFACE LOW MOVING ACROSS. LIGHT TO MODERATE RAIN
CONTINUES WEDNESDAY MORNING WITH STRONG COLD FRONT MOVING THROUGH BY
LATE AFTERNOON INTO EARLY EVENING. AS THE FRONT MOVES THROUGH EXPECT
RAIN TO CHANGE TO SNOW ACROSS MUCH OF THE AREA ALONG WITH BREEZY
WINDS. THE MILLION DOLLAR QUESTION IS HOW MUCH MOISTURE WILL BE
LEFT. MODELS HAVE BEEN CONSISTENT IN SHOWING THE HIGHLY AMPLIFIED
SYSTEM FOR SEVERAL DAYS OUT BUT HAVE NOT BEEN WITH THE EXACT
PLACEMENT OF THE LOW. THE LATEST FEW MODEL RUNS OF THE ECMW AND THE
GFS ARE TRENDING THE LOW FURTHER TO OUR WEST. THIS MEANS THAT THE
BULK OF THE MOISTURE WILL HAVE PASSED OFF TO OUR EAST BEFORE IT GETS
COLD ENOUGH TO SNOW BACK BEHIND THE COLD FRONT. IT LOOKS LIKE OUR
SNOW WILL BE IN THE FORM OF WRAP AROUND MOISTURE. THE CHANGEOVER TO
SNOW LOOKS TO OCCUR SOMETIME ON WEDNESDAY EVENING WITH SNOW
LINGERING THROUGH EARLY CHRISTMAS MORNING. MOST OF THE PRECIP DURING
THIS TIME FRAME SHOULD BE IN THE FORM OF SCATTERED LIGHT SNOW
SHOWERS. LITTLE TO NO ACCUMULATION EXPECTED AT THIS TIME FOR LOWER
ELEVATIONS. HIGHER ELEVATIONS MAY GET AN INCH OR TWO. AGAIN...ALL OF
THE ABOVE DEPENDS ON THE TRACK OF THE LOW...BUT THIS IS HOW IT`S
LOOKING FOR NOW.
THIS SYSTEM QUICKLY EXITS ON THURSDAY...CHRISTMAS DAY...AS IT RACES
OFF TO THE NORTHEAST. ANOTHER QUICK MOVING WEAKER SYSTEM MOVES
THROUGH ON FRIDAY INTO SATURDAY THAT COULD BRING SOME LIGHT SHOWERS
TO THE AREA.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 33 53 41 56 / 0 10 20 10
KNOXVILLE MCGHEE TYSON AIRPORT, TN 31 50 38 55 / 0 10 20 10
OAK RIDGE, TN 30 50 38 55 / 0 0 20 10
TRI CITIES AIRPORT, TN 30 48 35 51 / 0 10 30 40
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
DGS/SR
AREA FORECAST DISCUSSION
NWS AUSTIN/SAN ANTONIO TX
737 PM CST SUN DEC 21 2014
.UPDATE...
LATEST IR SATELLITE SHOWS LOW LEVEL CLOUD DECK DETERIORATING WEST
OF I35 CORRIDOR. KDRT SHOWING SOME LIGHT FOG ALREADY AT 01Z.
BOTH RUC AND HRRR INDICATE ZERO DEGREE DEWPOINT DEPRESSIONS ALONG
THE RIO GRANDE UP TO KDRT AND UP ONTO THE ESCARPMENT BEGINNING
AROUND 06Z. WITH A TIGHTENING SFC GRADIENT OVER OUR WEST AND
RESULTANT WINDS IN THE 10-15 MPH RANGE ALREADY...DONT THINK FOG
WILL BE ABLE TO SET IN ON THE ESCARPMENT MUCH...HOWEVER INCLUDED
AREAS OF FOG ALONG THE RIO GRANDE VALLEY AND SOUTH OF THE
ESCARPMENT BY 09Z. ALSO UPDATED SKY GRIDS...HOURLY T...AND HOURLY
DEW T GRIDS TO CAPTURE LATEST TRENDS.
&&
.PREV DISCUSSION... /ISSUED 630 PM CST SUN DEC 21 2014/
UPDATE...00Z AVIATION BELOW.
AVIATION...CLEARING HAS OCCURRED LATE THIS AFTERNOON AND EARLY
EVENING ALONG THE RIO GRANDE...WITH VFR CONDITIONS NOW AT DRT.
AT 00Z OVC MVFR STRATUS DECK STRETCHES FROM JUST NORTH OF DRT TO
SAT/SSF/AUS THEN ENCOMPASSES MOST AREAS ALONG AND EAST OF I-35
ACROSS SOUTH-CENTRAL TEXAS. SHALLOW MOISTURE TRAPPED BENEATH
INVERSION WILL CONTINUE OVERNIGHT...WITH SATURATION AND CLOUD DECK
LOWERING AFTER 06Z. HAVE INDICATED IFR CONDITIONS DEVELOPING
FIRST AT SAT/SSF AFTER 06Z AND LATER AT AUS AFTER 09Z. FORECAST
SOUNDINGS AND MOS INDICATE THERE COULD BE LIFR CEILINGS AND IFR
VISIBILITY DEVELOPING ALONG THE I-35 CORRIDOR TOWARDS DAYBREAK.
FARTHER WEST...HAVE INDICATED IFR CEILINGS DEVELOPING BACK TOWARDS
DRT AROUND 12Z...ALTHOUGH CONFIDENCE IS LOWER. SOUTHWEST AND
WESTERLY LOW LEVEL FLOW SHOULD PROMOTE BETTER MIXING AND CLEARING
ALONG AND WEST OF I-35 LATE MONDAY MORNING INTO THE EARLY
AFTERNOON.
PREV DISCUSSION... /ISSUED 339 PM CST SUN DEC 21 2014/
SHORT TERM (TONIGHT THROUGH MONDAY NIGHT)...
CLEARING HAS BEEN VERY STUBBORN THIS AFTERNOON BUT AREAS OUT WEST
AND SOUTHWEST ARE FINALLY STARTING TO SHOW SOME SUNSHINE. UPPER
TROF AXIS IS OVER THE STATE RIGHT NOW WITH MORE CLOUDINESS AND
MOISTURE UPSTREAM OVER THE ROCKIES. MOST AREAS WILL CLOUD BACK UP
OVERNIGHT AND HAVE MENTIONED SOME PATCHY FOG OVER SOUTHERN AREAS.
AREAS THAT CLEAR THIS EVENING WILL HAVE A BETTER CHANCE OF GETTING
THE FOG. LOW AND MID LEVEL WIND FIELDS WILL HAVE A WESTERLY
COMPONENT ON MONDAY MEANING WARMER TEMPERATURES AND MORE SUNSHINE.
MOST AREAS SHOULD REACH INTO THE 70S. SHOULD BE A VERY PLEASANT
DAY. ALTHOUGH WE LOSE THE LOW CLOUDS TOMORROW NIGHT WE WILL STILL
HAVE SOME MID AND HIGH CLOUDS AROUND WITH THE UPSTREAM SYSTEM OVER
THE ROCKIES. LOWS MONDAY NIGHT EXPECTED TO BE IN THE 40S TO LOW
50S.
LONG TERM (TUESDAY THROUGH SUNDAY)...
WILL SEE A COLD FRONT PUSH THROUGH THE CWA EARLY TUE MORNING WHILE A
DEEP TROF DEVELOPS OVER THE CENTRAL AND SOUTHERN PLAINS. AN UPPER
WAVE WILL PUSH SE OUT OF THE ROCKIES ON TUE WITH SOME OF ITS
ENERGY STAYING OVER SOUTH CENTRAL TEXAS EARLY WED. WITH THE COLD
FRONT AND UPPER LEVEL TROFFING...LOOKS LIKE TUE WILL BE MOSTLY
CLOUDY AND COOLER. 700 MB TROF AXIS SHIFTS EAST LATE TUE NIGHT
WHICH SHOULD MEAN A CLEARING PATTERN ON WED ALTHOUGH TEMPS WILL
REMAIN COOL AS THE SURFACE HIGH REMAINS OVER WEST TEXAS AND THE
ROCKIES. THE UPPER PATTERN FLATTENS AS TEXAS IS AT THE BASE OF A
LONG WAVE TROFFING PATTERN ACROSS MOST OF THE COUNTRY BY MID WEEK.
MOISTURE LEVELS WILL REMAIN LOW FOR THU AND FRI WHICH WILL
TRANSLATE TO MOSTLY SUNNY SKIES...COOL/COLD NIGHTS...AND COOL
AFTERNOON HIGHS IN THE 60S. WILL SEE A RETURN OF MORNING LOWS IN
THE 30S MIDDLE TO THE END OF THE WEEK. ANOTHER COLD FRONT IS
FORECAST FOR FRIDAY BUT SHOULD COME THROUGH DRY AS THERE WILL BE
LITTLE TO NO MOISTURE TO WORK WITH.
&&
.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY 52 71 48 57 38 / 10 - 10 20 -
AUSTIN BERGSTROM INTL AIRPORT 51 71 47 57 37 / 10 - 10 20 -
NEW BRAUNFELS MUNI AIRPORT 50 72 49 58 38 / 10 - 10 10 -
BURNET MUNI AIRPORT 48 70 45 54 36 / 10 - 10 20 -
DEL RIO INTL AIRPORT 43 75 48 59 37 / 10 - 10 10 -
GEORGETOWN MUNI AIRPORT 50 70 46 55 36 / 10 - 10 20 -
HONDO MUNI AIRPORT 48 73 46 61 34 / 10 - 10 10 -
SAN MARCOS MUNI AIRPORT 51 72 47 57 36 / 10 - 10 10 -
LA GRANGE - FAYETTE REGIONAL 52 72 51 56 39 / 10 - 10 20 -
SAN ANTONIO INTL AIRPORT 52 73 49 59 38 / 10 - 10 10 -
STINSON MUNI AIRPORT 51 72 50 60 38 / 10 - 10 10 -
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE/AVIATION...76
SYNOPTIC/GRIDS...03
PUBLIC SERVICE/DATA COLLECTION...12
AREA FORECAST DISCUSSION...UPDATED
NWS AUSTIN/SAN ANTONIO TX
1144 AM CST SAT DEC 20 2014
.AVIATION.../18Z TAFS/
MVFR CIGS CONTINUE ACROSS THE REGION. MORNING SOUNDINGS AT
KCRP/KDRT INDICATE INVERSIONS SO EXPECT CLOUD COVER TO HANG STRONG
INTO THE AFTERNOON. COULD SEE A FEW BREAKS DURING THE
AFTERNOON...MAINLY ACROSS THE WEST. WILL MAINTAIN MVFR CONDITIONS
INTO THE OVERNIGHT HOURS. SHOULD SEE IFR CONDITIONS DEVELOP
10Z-12Z THEN LIFT BACK TO MVFR/VFR SUNDAY AFTERNOON. WINDS WILL
REMAIN N/NE NEAR 10 KNOTS TODAY...SE NEAR 10 KNOTS AT KDRT. WILL
SEE A SOUTHERLY FLOW DEVELOP ON SUNDAY.
&&
.PREV DISCUSSION... /ISSUED 559 AM CST SAT DEC 20 2014/
AVIATION... /12Z TAF CYCLE/
LOW END MVFR CIGS ONGOING THIS MORNING FOR KSAT/KAUS/KSSF WITH
KDRT BOUNCING BETWEEN LOW MVFR AND VFR AS BKN010 TO SCT010 KEEP
BEING OBSERVED. WILL GO ON PESSIMISTIC SIDE FOR KDRT THROUGH
17-20Z BEFORE EVENTUAL BREAK OUT TO VFR OCCURS THIS AFTERNOON. FOR
CENTRAL SITES HOWEVER, FEEL MVFR WILL RULE THROUGH THE AFTERNOON
PER RAP/NAM SOUNDINGS AND HRRR OUTPUT. TOP OF STRATUS CLOUD DECK
LOOKS TO BE AROUND 3.5-4 KFT, RESULTING IN A 1-1.5 KFT THICK
STRATUS CLOUD LAYER. OVERNIGHT, IFR IS LIKELY FOR ALL SITES WITH
ANOTHER SLOW IMPROVEMENT TO MVFR/VFR ON SUNDAY AFTN.
SURFACE WINDS WILL BE N/NNE AT 10 KTS THROUGH THE DAY AND THEN
BECOME LIGHT AND VARIABLE OVERNIGHT TONIGHT. /ALLEN/
PREV DISCUSSION... /ISSUED 357 AM CST SAT DEC 20 2014/
SHORT TERM (TODAY THROUGH SUNDAY)...
AN UPPER LEVEL TROUGH SLOWLY DEVELOPS OVER THE PLAINS STATES. A
SERIES OF WEAK UPPER LEVEL SHORT-WAVES TRAVERSE THE TROUGH TO
GENERATE WEAK ISENTROPIC LIFT. MOISTURE DEPTH ONLY SUFFICIENT FOR
MAINTENANCE OF STRATUS/STRATOCUMULUS DECK WITH NO RAIN EXPECTED.
BELOW AVERAGE DAYTIME AND ABOVE AVERAGE NIGHTTIME TEMPERATURES ARE
EXPECTED DUE TO THE CLOUD COVER. PATCHY FOG WILL PERSIST ACROSS
HIGHER ELEVATIONS OF THE HILL COUNTRY THROUGH AROUND 9 AM THIS
MORNING.
LONG TERM (SUNDAY NIGHT THROUGH FRIDAY)...
THE UPPER LEVEL TROUGH SHIFTS EAST BY TUESDAY. SOUTHWESTERLY LOWER
LEVEL FLOW DEVELOPS ALLOWING SKIES TO MOSTLY CLEAR WITH WELL ABOVE
AVERAGE TEMPERATURES MONDAY. A MID LEVEL SHORT-WAVE MOVING THROUGH
THE TROUGH FORCES A COLD FRONT TO MOVE ACROSS SOUTH CENTRAL TEXAS
TUESDAY MORNING. THERE IS SUFFICIENT MOISTURE FOR ISOLATED SHOWERS
ALONG THE FRONT ACROSS FAR EASTERN AREAS AND HAVE INTRODUCED
MENTION. ZONAL FLOW ALOFT FOR MID TO LATE WEEK WITH AN UPPER LEVEL
TROUGH MOVING ACROSS THE PLAINS FORCING ANOTHER COLD FRONT ACROSS
SOUTH CENTRAL TEXAS FRIDAY. NO RAIN IS EXPECTED AS MOISTURE DEPTH
WILL BE MINIMAL. COOLER TEMPERATURES TUESDAY INTO WEDNESDAY...THEN
WARMER THURSDAY CHRISTMAS DAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY 56 44 60 48 70 / - - - - -
AUSTIN BERGSTROM INTL AIRPORT 56 42 59 46 70 / - - - - -
NEW BRAUNFELS MUNI AIRPORT 56 45 61 48 71 / - - - - -
BURNET MUNI AIRPORT 54 40 58 46 69 / - - - - -
DEL RIO INTL AIRPORT 60 45 62 46 73 / - - - - -
GEORGETOWN MUNI AIRPORT 54 40 58 47 69 / - - - - -
HONDO MUNI AIRPORT 59 45 62 46 72 / - - - - -
SAN MARCOS MUNI AIRPORT 57 43 61 46 70 / - - - - -
LA GRANGE - FAYETTE REGIONAL 57 45 61 48 71 / - - - - -
SAN ANTONIO INTL AIRPORT 57 45 61 49 72 / - - - - -
STINSON MUNI AIRPORT 58 46 62 49 72 / - - - - -
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE/AVIATION...10
SYNOPTIC/GRIDS...29
PUBLIC SERVICE/DATA COLLECTION...00
AREA FORECAST DISCUSSION...UPDATED
NWS AUSTIN/SAN ANTONIO TX
559 AM CST SAT DEC 20 2014
.AVIATION... /12Z TAF CYCLE/
LOW END MVFR CIGS ONGOING THIS MORNING FOR KSAT/KAUS/KSSF WITH
KDRT BOUNCING BETWEEN LOW MVFR AND VFR AS BKN010 TO SCT010 KEEP
BEING OBSERVED. WILL GO ON PESSIMISTIC SIDE FOR KDRT THROUGH
17-20Z BEFORE EVENTUAL BREAK OUT TO VFR OCCURS THIS AFTERNOON. FOR
CENTRAL SITES HOWEVER, FEEL MVFR WILL RULE THROUGH THE AFTERNOON
PER RAP/NAM SOUNDINGS AND HRRR OUTPUT. TOP OF STRATUS CLOUD DECK
LOOKS TO BE AROUND 3.5-4 KFT, RESULTING IN A 1-1.5 KFT THICK
STRATUS CLOUD LAYER. OVERNIGHT, IFR IS LIKELY FOR ALL SITES WITH
ANOTHER SLOW IMPROVEMENT TO MVFR/VFR ON SUNDAY AFTN.
SURFACE WINDS WILL BE N/NNE AT 10 KTS THROUGH THE DAY AND THEN
BECOME LIGHT AND VARIABLE OVERNIGHT TONIGHT. /ALLEN/
&&
.PREV DISCUSSION... /ISSUED 357 AM CST SAT DEC 20 2014/
SHORT TERM (TODAY THROUGH SUNDAY)...
AN UPPER LEVEL TROUGH SLOWLY DEVELOPS OVER THE PLAINS STATES. A
SERIES OF WEAK UPPER LEVEL SHORT-WAVES TRAVERSE THE TROUGH TO
GENERATE WEAK ISENTROPIC LIFT. MOISTURE DEPTH ONLY SUFFICIENT FOR
MAINTENANCE OF STRATUS/STRATOCUMULUS DECK WITH NO RAIN EXPECTED.
BELOW AVERAGE DAYTIME AND ABOVE AVERAGE NIGHTTIME TEMPERATURES ARE
EXPECTED DUE TO THE CLOUD COVER. PATCHY FOG WILL PERSIST ACROSS
HIGHER ELEVATIONS OF THE HILL COUNTRY THROUGH AROUND 9 AM THIS
MORNING.
LONG TERM (SUNDAY NIGHT THROUGH FRIDAY)...
THE UPPER LEVEL TROUGH SHIFTS EAST BY TUESDAY. SOUTHWESTERLY LOWER
LEVEL FLOW DEVELOPS ALLOWING SKIES TO MOSTLY CLEAR WITH WELL ABOVE
AVERAGE TEMPERATURES MONDAY. A MID LEVEL SHORT-WAVE MOVING THROUGH
THE TROUGH FORCES A COLD FRONT TO MOVE ACROSS SOUTH CENTRAL TEXAS
TUESDAY MORNING. THERE IS SUFFICIENT MOISTURE FOR ISOLATED SHOWERS
ALONG THE FRONT ACROSS FAR EASTERN AREAS AND HAVE INTRODUCED
MENTION. ZONAL FLOW ALOFT FOR MID TO LATE WEEK WITH AN UPPER LEVEL
TROUGH MOVING ACROSS THE PLAINS FORCING ANOTHER COLD FRONT ACROSS
SOUTH CENTRAL TEXAS FRIDAY. NO RAIN IS EXPECTED AS MOISTURE DEPTH
WILL BE MINIMAL. COOLER TEMPERATURES TUESDAY INTO WEDNESDAY...THEN
WARMER THURSDAY CHRISTMAS DAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY 56 44 60 48 70 / - - - - -
AUSTIN BERGSTROM INTL AIRPORT 56 42 59 46 70 / - - - - -
NEW BRAUNFELS MUNI AIRPORT 56 45 61 48 71 / - - - - -
BURNET MUNI AIRPORT 54 40 58 46 69 / - - - - -
DEL RIO INTL AIRPORT 60 45 62 46 73 / - - - - -
GEORGETOWN MUNI AIRPORT 54 40 58 47 69 / - - - - -
HONDO MUNI AIRPORT 59 45 62 46 72 / - - - - -
SAN MARCOS MUNI AIRPORT 57 43 61 46 70 / - - - - -
LA GRANGE - FAYETTE REGIONAL 57 45 61 48 71 / - - - - -
SAN ANTONIO INTL AIRPORT 57 45 61 49 72 / - - - - -
STINSON MUNI AIRPORT 58 46 62 49 72 / - - - - -
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE/AVIATION...15
SYNOPTIC/GRIDS...04
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1117 PM CST FRI DEC 19 2014
.DISCUSSION...
SEE 06Z AVIATION DISCUSSION.
&&
.AVIATION...
NAM12 AND RAP SOUNDINGS CONTINUE TO ADVERTISE IFR CIGS OVERNIGHT
WITH GRADUAL IMPROVEMENT SATURDAY AFTN. VFR CONDS EVENTUALLY
EXPECTED BY 21/2100Z. WINDS WILL REMAIN LIGHT OVERNIGHT EXCEPT
NEAR THE COAST. SOME PATCHY FOG WILL ALSO BE POSSIBLE THROUGH THE
OVERNIGHT HOURS. 43
&&
.PREV DISCUSSION... /ISSUED 828 PM CST FRI DEC 19 2014/
UPDATE...
A STRATUS DECK REMAINS IN PLACE ACROSS SOUTHEAST TEXAS
TONIGHT...WITH AMDAR SOUNDINGS INDICATING THE DEPTH OF THESE
LOW CLOUDS AROUND 1000 FT. THIS CLOUD LAYER IS THIN ENOUGH TO
ALLOW FOR SUFFICIENT RADIATIONAL COOLING FOR FOG DEVELOPMENT AND
SEVERAL OBSERVATION SITES WERE ALREADY REPORTING MINOR REDUCTIONS
IN VISIBILITY AS OF 8 PM. HAVE ADDED PATCHY FOG INTO THE FORECAST
AND REMOVED RAIN MENTION OVER THE COASTAL WATERS AS ALL ACTIVITY
HAS MOVED EAST OF THE AREA. OTHERWISE... FORECAST REMAINS ON TRACK
FOR TONIGHT WITH GENERALLY LIGHT NORTHERLY WINDS IN PLACE AND LOWS
FALLING INTO THE MID TO UPPER 40S INLAND AND NEAR 50 ALONG THE
COAST.
HUFFMAN
PREV DISCUSSION... /ISSUED 545 PM CST FRI DEC 19 2014/
DISCUSSION...
SEE 00Z AVIATION DISCUSSION.
AVIATION...
RAP AND NAM12 FCST SOUNDINGS MAINTAIN IFR CIGS OVERNIGHT WITH SLOW
IMPROVEMENT TO MVFR ON SATURDAY. WET GROUNDS AND LIGHT WINDS WILL
ALSO LEAD TO AT LEAST SOME PATCHY FOG OVERNIGHT AS WELL. WINDS
WILL GRADUALLY RELAX THIS EVENT EXCEPT ALONG THE IMMEDIATE COAST.
43
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 47 56 46 59 46 / 10 0 0 0 0
HOUSTON (IAH) 49 58 46 60 46 / 10 0 0 0 0
GALVESTON (GLS) 51 57 52 59 52 / 10 10 10 10 0
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 4 AM CST SATURDAY FOR
THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY.
SMALL CRAFT ADVISORY UNTIL 6 AM CST SATURDAY FOR THE FOLLOWING
ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
20 NM TO 60 NM...WATERS FROM FREEPORT TO THE MATAGORDA SHIP
CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20
TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM.
&&
$$
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
929 PM CST SUN DEC 21 2014
.UPDATE...
00Z NAM MODEL SOUNDINGS SHOW THE LOW LEVEL SATURATION TO AROUND 4
THSD FT WITH DRY LAYER ABOVE UNTIL 10 THSD FT. THEN SOUNDINGS
SATURATE AGAIN. THIS IS IN THE DENDRIDIC GROWTH ZONE...HOWEVER TOO
MUCH SEPARATION FOR ANY SEEDER FEEDER MECHANISM.
00Z NAM TRACKS THE INITIAL SURFACE LOW ACROSS SOUTHERN WISCONSIN
JUST TO THE WEST AND NORTH OF MADISON. DESPITE THE 18Z GFS MOVING
THE SECONDARY LOW BACK WESTWARD...THE 00Z NAM CONTINUES THE EAST
TRACK OF THE SECONDARY LOW WEDNESDAY NIGHT AND THURSDAY MORNING.
&&
.AVIATION/06Z TAFS/...
00Z NAM MODEL SOUNDINGS SHOW THE LOW LEVEL SATURATION TO AROUND 4
THSD FT WITH DRY LAYER ABOVE UNTIL 10 THSD FT. THEN SOUNDINGS
SATURATE AGAIN. IFR CIGS WILL SPREAD SLOWLY NORTHEAST ACROSS THE
FORECAST AREA TONIGHT AND INTO MONDAY. OVERALL MODELS KEEP MOST OF
THE MEASURABLE PRECIP ACROSS WRN AND NORTHERN WI WITH LESS IN THE
SE. WITH LOW PRESSURE AND A MORE ORGANIZED SHORTWAVE APPROACHING
MONDAY AFTERNOON/EVENING EXPECT MORE WIDESPREAD RAINFALL MOVING
INTO SRN WI. THE AREA OF ABOVE ZERO CELSIUS TEMPERATURES INCREASES
TOWARDS MONDAY NIGHT.
&&
.PREV DISCUSSION... /ISSUED 303 PM CST SUN DEC 21 2014/
REST OF THIS AFTERNOON AND TONIGHT - CONFIDENCE...MEDIUM
LEAD WAVE COMBINED WITH WAA GENERATING LIGHT PRECIP RETURNS ACROSS
WRN CWA. HOWEVER 88-D TRENDS SHOW COVERAGE DECREASING RAPIDLY WITH THIS.
SPOTTY LIGHT RAIN OR LIGHT SNOW WITH THIS BAND. MOIST FLOW CONTINUES
AHEAD OF ADVANCING LOW PRESSURE TROUGH IN THE PLAINS. SURFACE TEMPS
NOT EXPECTED TO DROP MUCH DUE TO SOUTHERLY WINDS AND CLOUD COVER. MID
LEVEL SHORTWAVE EXPECTED TO AMPLIFY AS IT DRAWS CLOSER. WEAKER SHORTWAVE
TO BRUSH SRN WI AFTER 6Z. WILL KEEP POPS CONFINED TO NW CWA CLOSER TO
850 LLJ AXIS AND AREA OF MODEL QPF. WITH MID LEVELS SHOWING A DRY LOOK
ON BUFKIT SOUNDINGS AND ANTICIPATED TEMPS REMAINING ABV ZERO NOT
EXPECTING ANY FREEZING RAIN/DRIZZLE.
MONDAY - CONFIDENCE...MEDIUM
NEARLY STACKED LOW MOVERS INTO WESTERN IOWA. SHORTWAVE ENERGY WRAPPING
AROUND THIS UPPER LOW SHIFTS INTO SRN WI AND COINCIDES WITH INCREASING
850 MILLIBAR WIND MAX DURING THE AFTERNOON HOURS. MILD AIRMASS WITH HIGHS
IN THE U30S/L40S EXPECTED. NAM SOUNDING IN NW CWA LOOK A SMIDGE COLD
IN THE LOW LEVELS. PREFER THE BETTER HANDLING OF LOW LEVEL TEMP PROFILE
ON THE GFS SOUNDING. BUT PRECIP TYPE STILL QUESTIONABLE INTO THE AFTERNOON
ACROSS THE NW CWA. AREA SOUNDINGS SHOWING SN POTENTIAL WITH SATURATION IN THE
DENDRIDIC GROWTH ZONE. HOWEVER LOW LEVELS WILL DETERMINE EVENTUAL PRECIP
TYPE. SO WILL STILL KEEP MIXED PRECIP INTO THE AFTERNOON THERE WITH VRY LGT
ACCUMS. MUCH OF CWA EXPECTED TO BE RAIN IN THE AFTN THOUGH THE NW IS STILL
VULNERABLE WITH LOWEST 850 TEMPS AND COLDEST 1000-500 MILLIBAR THICKNESSES.
MONDAY NIGHT AND TUESDAY...FORECAST CONFIDENCE IS HIGH.
FAIRLY STRONG DYNAMICS ARRIVE MONDAY NIGHT AS THE MAIN CLOSED MID
LEVEL LOW SPINS OVER IOWA INTO SOUTHERN MN...EJECTING DECENT SHORT
WAVE ENERGY NORTHEAST INTO WISCONSIN. THE ASSOCIATED SURFACE LOW
WILL TRACK FROM NORTHWEST IOWA TO NORTH CENTRAL WISCONSIN BETWEEN
6 PM MONDAY THROUGH MID-DAY ON TUESDAY. DECENT WARM AIR ADVECTION
AHEAD OF THE LOW...RESULTING IN STRONG Q-VECTOR CONVERGENCE WHEN
COUPLED WITH THE MID LEVEL SHORT WAVE...SUPPORTS VERY HIGH POPS
INTO THE EVENING. TEMP PROFILES SUPPORT ALL RAIN WITH THE
POSSIBILITY OF A RAIN/SNOW MIX NORTHWEST OF MADISON.
WE SHOULD GET DRY SLOTTED LATER MONDAY NIGHT THROUGH TUESDAY WITH
LOW POPS MOVING IN. LIKELY JUST ANOTHER CLOUDY DAY WITH A SMALL
CHANCE OF RAIN OR SOME DRIZZLE AS THIS FIRST LOW MOVES OFF TO THE
NORTHEAST. TEMPS WILL BE MILD AS WE REMAIN ON THE WARM SIDE OF
THE LOW/TROF.
TUESDAY NIGHT THROUGH WEDNESDAY...FORECAST CONFIDENCE
INCREASING.
IF YOU/VE BEEN FOLLOWING THE DISCUSSIONS...YOU KNOW THERE HAS BEEN
AN INCREDIBLE AMOUNT OF MODEL VARIABILITY IN THE HANDLING OF THE
SECONDARY LOW PRESSURE DEVELOPMENT COMING OUT OF THE LOWER
MISSISSIPPI VALLEY FOR THIS PERIOD. THE NEW 12Z RUNS ARE MUCH
TIGHTER AND THE LOWER SPREADS IN POSSIBLE SOLUTIONS PROVIDES
HIGHER CONFIDENCE. THE CONSENSUS LOW TRACK IS FROM THE OHIO VALLEY
NEAR LOUISVILLE TO SOUTHEAST LOWER MICHIGAN...THEN NORTHEAST FROM
THERE. THE SOUTHEAST WISCONSIN FORECAST AREA...INCLUDING THE
MILWAUKEE METRO AREA COULD GET INTO THE FAR WESTERN PRECIP SHIELD
AND GENERATE SOME LIGHT SNOW. BUT TEMPS WOULD PROBABLY STILL BE
WARM ENOUGH TO MELT MOST OF IT.
THE GFS/ECMWF/NAM/GEM KEEP THE HIGHEST IMPACT WEATHER WELL EAST
OF US. OF MINOR CONCERN IS A 12Z SUN PARALLEL HIGH RESOLUTION RUN
OF THE GFS THAT SHOWS A MAJOR LOW MOVING FROM ST. LOUIS TO
MILWAUKEE DURING THIS TIME. IT HAS BEEN ASSESSED AS A SIGNIFICANT
OUTLIER...NOT CLOSE TO ANY OTHER ENSEMBLE RUNS...AND IS BEING
DISCARDED. I MENTION IT AS THIS SOLUTION MAY MAKE IT/S WAY OUT
INTO THE SOCIAL MEDIA WORLD AND RAISE QUESTIONS. AND THE
CAVEAT...WE CAN/T LET OUR GUARD DOWN. THE TRACKS OF THESE LOWS CAN
CHANGE...SO REMAIN UP TO DATE ON THE LATEST FORECAST THROUGH
CHRISTMAS EVE.
CHRISTMAS DAY...FORECAST CONFIDENCE IS HIGH.
FOR ALL THOSE PLANNING TO TRAVEL ON THE HOLIDAY...IT LOOKS LIKE A
DECENT DAY WITH DRY WEATHER AS HIGH PRESSURE BRIEFLY BUILDS IN.
TEMPS WILL BE IN THE LOWER TO MID 30S.
FRIDAY...FORECAST CONFIDENCE IS MEDIUM.
LATE THURSDAY NIGHT AND FRIDAY...A FAST MOVING SHORT WAVE ARRIVES
IN THE ZONAL FLOW AND COULD BRING AROUND AN INCH OF SNOW. THE GFS
IS MUCH FARTHER NORTH WITH THE SFC LOW TRACK COMPARED TO THE
ECMWF AND THIS HAS BEEN THE CASE FOR THE LAST FEW RUNS. WPC IS
FAVORING THE ECMWF WHICH WILL SUPPORT A COLDER SOLUTION...WITH
THAT INCH OF SNOW POSSIBLE.
SATURDAY AND SUNDAY...FORECAST CONFIDENCE IS MEDIUM.
LOOKS LIKE HIGH PRESSURE RETURNS FOR NEXT WEEKEND. IT LOOKS DRY
WITH TEMPS RUNNING BELOW NORMAL...GENERALLY HIGHS IN THE LOWER TO
MID 20S.
AVIATION/00Z TAFS/...COMBO OF SHORTWAVE TROUGH MOVING EAST FROM WRN
MN AND WRN IA ALONG WITH SUSTAINED WAA...RESULTING IN MOST
WIDESPREAD PRECIP ACRS EC MN INTO NW WI. BAND OF MORE SCATTERED
PRECIP EXTENDS SOUTHWARD THROUGH SC WI. THIS WILL CONTINUE TO
TRANSLATE EWD THIS AFTN/ERLY EVE MOVING THROUGH THE REST OF SRN WI.
SFC TEMPS ABV FREEZING. RAP BUFKIT SOUNDINGS SHOW THE LOW LEVEL
SATURATION WITH DRY LAYER ABV AND HINTS OF MID LEVEL SATURATION
WITHIN DENDRIDIC GROWTH ZONE...SO CANNOT RULE OUT SOME SNOW...THOUGH
SEEDER FEEDER DRY DEPTH IS FAIRLY LARGE. IFR CIGS AND VSBYS WILL
PREVAIL WITH THE NAM MOS AND CONSSHORT HAVING THE BEST HANDLE ON
CIG/VSBY TRENDS. OVERALL MODELS KEEP MOST OF PRECIP THIS PERIOD
ACROSS WRN AND NRN WI WITH LESS IN THE SE. WITH LOW PRESSURE AND
MORE ORGANIZED SHORTWAVE APPROACHING MONDAY AFTERNOON/EVENING EXPECT
MORE WIDESPREAD RAINFALL MOVING INTO SRN WI. ANY MIXY POTENTIAL
LOOKS TO BE NORTH OR NORTHWEST OF TAF SITES.
MARINE...A SMALL CRAFT ADVISORY IS IN EFFECT FROM PORT WASHINGTON
AND NWD AND STARTS AT 10 PM SOUTH OF PORT WASHINGTON. AS LOW
PRESSURE APPROACHES FROM THE NORTHERN PLAINS...BREEZY SOUTH TO
SOUTHEAST WINDS WILL CONTINUE TO RAMP UP INTO MONDAY NIGHT. THE
SOUTHERLY FETCH WILL GENERATE HIGH WAVES DURING THIS PERIOD. THE
WINDS AND WAVES WILL SUBSIDE ON TUESDAY AS THE WEAKENING LOW
PRESSURE AREA MOVES ACROSS THE REGION. THE SMALL CRAFT ADVISORY WILL
EXPIRE EARLY TUE AM.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 3 AM CST TUESDAY FOR LMZ644>646.
SMALL CRAFT ADVISORY UNTIL 6 AM CST TUESDAY FOR LMZ643.
&&
$$
UPDATE...HENTZ
TONIGHT/MONDAY AND AVIATION/MARINE...COLLAR
MONDAY NIGHT THROUGH SUNDAY...DAVIS
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1036 PM MST SUN DEC 21 2014
.UPDATE...
ISSUED AT 831 PM MST SUN DEC 21 2014
ANOTHER UPDATE TO RAISE POPS OVER THE ERN PLAINS WHERE PERSISTENT
LIGHT BANDED RAIN SHOWERS HAVE BEEN MOVING...ALTHOUGH MOST OF THE
PRECIP NOT LIKELY REACHING THE GROUND. ALSO BUMPED UP POPS FOR THE
NRN SAN LUIS VALLEY WHERE PERSISTENT LIGHT SNOW HAS BEEN FALLING.
LATEST HRRR SHOWS PRECIP DIMINISHING FOR THE PLAINS EARLY MON
MORNING. ROSE
UPDATE ISSUED AT 544 PM MST SUN DEC 21 2014
UPDATED GRIDS/ZONES PER LATEST OBS AND RADAR TRENDS AS WELL
AS LATEST HI RES GUIDANCE. MAIN CHANGES WERE TO BUMP UP POPS
SLIGHTLY OVER THE DVD SO THAT CATEGORICAL POPS ARE THERE FOR THE
HIGHER ELEVATIONS...AND ADDED BORDERLINE MENTIONABLE (10 PERCENT)
POPS FOR EL PASO COUNTY THIS EVE. LOOKS LIKE MOST OF THE PRECIP
WILL STAY OUT OVER KIOWA COUNTY...BUT CANNOT RULE OUT SOME SMALL
BANDS OF SHOWERS MOVING OVER THE I-25 CORRIDOR AS WELL. ROSE
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 320 PM MST SUN DEC 21 2014
...HEAVY SNOW TO CONTINUE IN THE MTNS...
CURRENTLY...
RADAR AND SFC OBS SHOW WIDESPREAD SNOW IN THE HIGH COUNTRY. KLXV
WEBCAMS SHOW SOME PRETTY DECENT ACCUMS IN TOWN. KGJT SHOWS
WIDESPREAD PRECIP ALONG THE WEST SLOPE MOVING RAPIDLY SE IN THE
STRONG NW FLOW ALOFT. AT LOWER ELEVATIONS...WIDESPREAD HIGH
CLOUDINESS DOMINATES ACROSS THE PLAINS. TEMPS WERE MILD WITH MAINLY
50S...WITH THE WARMEST TEMPS AT CANON CITY AND KSPD. GUSTY WINDS
PREVAILED IN THE MTNS AND GAP AREAS...WITH WINDS GUSTING TO 40 MPH
IN GAP AREAS.
TODAY THRU TONIGHT...
HEAVY WIND DRIVEN SNOW WILL CONTINUE ACROSS THE C MTNS AND NW SLOPES
OF THE LA GARITA MTNS. A FOOT OR MORE OF ADDITIONAL SNOW IS NEAR
CERTAIN.
OVER THE REMAINDER OF THE MTNS...SNOW OVER THE HIGH COUNTRY IS
EXPECTED TO GRADUALLY DROP SOUTHEAST WITH TIME...AND SNOW SHOULD BE
INCREASING MOST MTN AREAS AFTER MIDNIGHT. THE NORTHERN SAN LUIS
VALLEY SHOW START TO SEE SNOW DURING THE EARLY MORNING HOURS. A FEW
SNOW SHOWERS WILL BE POSSIBLE ON THE PLAINS...BUT NO SIGNIF ACCUMS
ARE ANTICIPATED.
AMBIENT TEMPS TONIGHT SHOULD REMAIN RELATIVELY MILD...WITH LOWS
IN THE U20S PLAINS...AND TEENS AND 20S MTNS. WITH THE STRONG WINDS
OVER THE HIGHER TERRAIN...WIND CHILLS WILL BE SHARPLY COLDER.
WINDS OVER THE MTNS WILL RANGE IN THE 30-50 MPH RANGE TONIGHT.
TOMORROW...
SNOW...HEAVY AT TIMES...WILL CONTINUE IN THE MTNS ALONG THE CONTDVD
AND NW FACING SLOPES OF THE LA GARITAS. SNOW WILL LIKELY SLACKEN
AS THE AFTERNOON PROGRESSES TOMORROW. WINDS WILL LESSEN A BIT OVER
THE HIGHER TRRN BUT WILL INCREASE ACROSS THE PLAINS BY AFTERNOON
AS THE STRONG JET MOVES OUT OVER THE MTNS AND LAPSE RATES INCREASE
AS COLDER AIR MOVE IN ALOFT. BY MIDAFTERNOON TOMORROW...LAPSE
RATES WILL INCREASE TO 8-9 C/KM AND THIS WILL ALLOW FOR CONVECTIVE
SNOW SHOWERS TO DEVELOP OVER THE PLAINS. THE BEST CHANCE OF SNOW
SHOWERS AT LOWER ELEVATIONS WILL BE OVER THE PALMER DIVIDE AND THE
EAST FACING SLOPES OF THE WETS/SANGRES AND RATON MESA/SPANISH
PEAKS REGIONS.
IT WILL BE COLDER TOMORROW OVER THE PLAINS...WITH TEMPS 10F OR SO
COLDER THAN TODAY. IT WILL FEEL MUCH COLDER AS THE WINDS INCREASE
FROM THE NW DURING THE AFTERNOON. HI TEMPS TOMORROW WILL LIKELY
OCCUR AROUND OR SHORTLY AFTER NOONTIME.
I CANNOT RULE OUT SOME SNOW BANDS DROPPING A COUPLE INCHES OF SNOW
ON THE PLAINS TOMORROW. HOWEVER...GUIDANCE HAS BEEN GRADUALLY
BACKING OFF ON THIS SCENARIO. WHERE THESE BANDS SET UP IS ANYONES
GUESS...BUT THE OVERALL BEST CHANCE OF ANY PRECIP AT THE LOWER
ELEVATIONS APPEARS TO BE ON THE PALMER DVD AND SPANISH PEAKS/RATON
MESA REGION (LAS ANIMAS/HUERFANO COUNTY REGION).
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 320 PM MST SUN DEC 21 2014
MONDAY NIGHT AND TUESDAY...THE UPPER LOW OVER THE MIDWEST MONDAY
NIGHT WILL SLIDE GRADUALLY TO THE NE TOWARDS THE GREAT
LAKES...ELONGATING THE UPPER TROUGH DOWN INTO TX TUE MORN. THIS WILL
ALLOW THE 140 KT UPPER JET TO DROP DOWN INTO WESTERN CO AND CREATE
VERY STRONG WINDS FOR THE FORECAST AREA. SO...ONGOING WINTER
HIGHLIGHTS WILL END MON EVE AND THE THREAT THEN BECOMES MORE OF A
WIND PROBLEM AS OPPOSED TO A SNOW ACCUMULATION PROBLEM. SNOW IS
EXPECTED TO LINGER OVER THE E PLAINS AND SOUTHERN FOOTHILLS THROUGH
TUE MORN...BUT VERY STRONG NORTHERLY WINDS TUE AFTN AND EVE ARE
EXPECTED...AND EVEN THOUGH AIR TEMP SHOULD BE IN THE MID TO UPPER
30S...WIND CHILLS WILL BE IN THE TEENS TO EVEN SINGLE DIGITS.
TUESDAY NIGHT AND WEDNESDAY...THIS STILL LOOKS TO BE A TRANSITIONAL
DAY AS NORTHERLY FLOW BECOMES MORE WESTERLY THROUGH WED AFTN AHEAD
OF THE NEXT APPROACHING SYSTEM. TEMPS ARE EXPECTED TO REBOUND INTO
THE MID TO UPPER 40S FOR THE PLAINS...AND INTO THE UPPER 30S TO 40S
FOR THE HIGH VALLEYS.
THURSDAY THROUGH SUNDAY...MODELS ARE HAVING A HARD TIME COMING UP
WITH A SOLUTION FOR CHRISTMAS AND THE WEEKEND. BOTH EC AND GFS ARE
INDICATING ANOTHER TROUGH MOVING IN...BUT KEEPING MUCH OF THE
ACTIVITY TO THE NORTH. IT LOOKS LIKE THE CONTDVD AND ESPECIALLY THE
CENTRAL MTS ARE SET UP TO GET SOME MORE SNOW STARTING VERY EARLY THU
MORNING AND LASTING THROUGH FRI...THOUGH THE EC ALSO SHOWS SOME PCPN
WITH A COLD FRONT PASSAGE FOR THE PLAINS LATE THU. FEEL THAT IS
HIGHLY SUSPECT...SO EVEN THOUGH ISOLATED POPS ARE INCLUDED FOR THE
PALMER DVD AND EL PASO COUNTY...KEPT MUCH OF THE E PLAINS DRY.
CLOUDY AND A BIT WINDY...BUT DRY. EXPECT A RATHER MILD DAY ON THU
AHEAD OF THIS SYSTEM...THEN 15 TO 20 DEGREES COLDER ON FRI. AS FOR
SAT AND SUN...MODEL DISAGREEMENT CONTINUES...THOUGH A GENERAL
WESTERLY FLOW ALOFT LOOKS TO BE IN PLACE THROUGH SUN. FEEL THE BEST
BET IS TO INCLUDE ISOLATED POPS FOR THE HIGHER ELEVATIONS ON SUN
WITH A GRADUAL WARMING TREND THROUGH THE WEEKEND. MOORE
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1033 PM MST SUN DEC 21 2014
SCT SHRASN WILL TEMPORARILY WIND DOWN AFTER ABOUT 09Z TONIGHT.
ANOTHER ROUND OF SCT SHOWERS IS EXPECTED MON AFTERNOON AND
LASTING THROUGH MON EVENING. IT WILL BE SPOTTY IN NATURE...BUT
COULD RESULT IN BRIEF MVFR CONDITIONS FOR THE TERMINALS. OTHER
CONCERN WILL BE INCREASING N WINDS ON THE BACK SIDE OF THIS
SYSTEM. COULD SEE SOME GUSTS IN THE 30 KT RANGE MON EVENING
FOR KCOS AND KPUB. THE CENTRAL MTS WILL CONTINUE TO SEE HEAVY
SN THROUGH THE PERIOD...WITH SN AND BLSN OVER THE DVD ESPECIALLY
N OF KMYP. ROSE
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 5 PM MST MONDAY FOR COZ064-066.
WINTER WEATHER ADVISORY UNTIL 11 PM MST MONDAY FOR COZ061.
WINTER STORM WARNING UNTIL 11 PM MST MONDAY FOR COZ058>060.
&&
$$
UPDATE...ROSE
SHORT TERM...HODANISH
LONG TERM...MOORE
AVIATION...ROSE
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
926 PM MST SUN DEC 21 2014
.UPDATE...
ISSUED AT 847 PM MST SUN DEC 21 2014
SHOWERS HAVE ALSO MANAGED TO SPILL ACROSS THE FRONT RANGE AS
INSTABILITY HAS INCREASED THIS EVENING. THERE MAY BE SOME
POTENTIAL INSTABILITY WITH DRYING NOTED ALOFT...AND CELLS HAVE
BECOME QUITE CONVECTIVE WITH ISOLATED LIGHTNING INDICATED IN THE
COLORADO LIGHTNING MAPPING ARRAY. MEANWHILE...FRONT IS MOVING
ACROSS THE CO/WY BORDER AS OF 830 PM WITH ANOTHER AREA OF
PRECIPITATION...MOSTLY SNOW...BEHIND IT. HAVE INCREASED POPS FOR
MOST OF THE PLAINS TO ACCOUNT FOR BOTH OF THESE FEATURES. SHORT
RANGE RAP AND HRRR ARE NOT HANDLING THIS PRECIPITATION WELL AT
ALL. A FEW SPOTS COULD SEE AN INCH OR TWO OF SNOW ON THE PLAINS
IF SHOWERS BECOME MORE PERSISTENT AS INTENSITY/CONVECTIVE
PARAMETER IS THERE.
UPDATE ISSUED AT 652 PM MST SUN DEC 21 2014
BAND OF SHOWERS IS ORGANIZING ON THE EASTERN PLAINS EARLY THIS
EVENING...FROM NEAR CHEYENNE TO FORT MORGAN AND EAST OF LIMON.
THIS FEATURE SEEMS RATHER SLOW MOVING. MOST OF THIS WILL BE RAIN
BEFORE COLD FRONT ARRIVES LATER IN THE EVENING. THE ARRIVAL OF
THIS FEATURE AND A MORE NORTHERLY LOW LEVEL COMPONENT COULD SHIFT
THE BAND BACK TOWARD THE I-25 CORRIDOR OVERNIGHT...BUT STILL
FAVORING LOCATIONS EAST OF I-25. MOUNTAIN HEAVY SNOW EVENT IS
UNDERWAY WITH MOSTLY 3-6 INCH AMOUNTS BUT A FEW SPOTS ALREADY
APPROACHING A FOOT TOWARD THE COLUMBINE AND TOWER SNOTELS...AND
ALSO NEAR COPPER MOUNTAIN. THE HEAVIEST SNOW IS STILL ON TRACK TO
OCCUR THIS EVENING BUT THERE WAS SOME DRYING NOTED ON THE RIVERTON
WYOMING SOUNDING BETWEEN 700 MB AND 500 MB...WHICH SHOULD RESULT
IN LOWER SNOW INTENSITY AFTER MIDNIGHT. UNTIL THEN...ONE HALF TO
ONE INCH PER HOUR SNOW AMOUNTS WILL CONTINUE OVER MOST OF THE HIGH
COUNTRY. HAZARDOUS AND SLOW DRIVING CONDITIONS WILL REMAIN IN
PLACE THROUGH MONDAY WITH CONTINUED WINTER STORM WARNING.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 326 PM MST SUN DEC 21 2014
SNOW WILL CONTINUE IN THE MOUNTAINS OVERNIGHT TAPERING OFF
STARTING MONDAY EVENING. UPSTREAM OBS SHOW VISIBILITIES REDUCING
DOWN TO HALF A MILE WITH THE HEAVIER SNOW. CURRENT WARNING
PRODUCTS STILL ON TRACK BUT OVERNIGHT SHIFTS MAY NEED TO RE-ASSESS
END TIMES DUE TO RECENT MODEL RUNS MOVING THE JET OUT SOONER. THE
LINGERING MOISTURE AND OROGRAPHIC FLOW WILL STILL PRODUCE SOME
SNOW SHOWERS OVER THE MOUNTAINS TOMORROW BUT THE INTENSITY WILL
DECREASE. CONTINUING TO URGE TRAVELERS TO USE CAUTION AS WINDS
OVER THE HIGHER MOUNTAIN PASSES WILL GUST UP TO 60 MPH THIS
EVENING. CONSIDERABLE BLOWING AND DRIFTING SNOW ALONG WITH
VISIBILITIES BELOW A QUARTER OF A MILE WILL OCCUR OVER AREAS SUCH
AS LOVELAND PASS...BERTHOUD PASS AND RABBIT EARS PASS. OTHER WELL
TRAVELED AREAS ALONG I-70 SUCH AS THE TUNNEL WILL ALSO SEE GREATLY
REDUCED VISIBILITIES WITH ICY AND SNOWY ROADWAYS. TRAVELERS ARE
URGED TO USE CAUTION AND DELAY PLANS TO TRAVEL OVER THE MOUNTAINS
THIS EVENING IF AT ALL POSSIBLE.
FOR THE PLAINS DOWNSLOPING WINDS WILL KEEP AREAS ALONG THE
FOOTHILLS 4-5 DEGREES WARMER AND DRY WITH WINDS GUSTING UP TO 60
MPH OVER THE WIND PRONE AREAS. WINDS WILL MOVE TO A MORE NORTHERLY
DIRECTION EARLY TOMORROW MORNING BRINGING COOLER CONDITIONS ALONG
WITH A CHANCE OF SNOW EAST OF I-25. IN ADDITION TO THE INFLUX OF
MOISTURE OVER THE PLAINS THERE IS SOME INSTABILITY SO SOME AREAS
COULD HAVE SOME LIGHT ACCUMULATION...WITH UP TO 2 INCHES POSSIBLE
UNDER THE HEAVIER BANDS. TEMPERATURES FOR TOMORROW WILL BE COOLER
WITH HIGHS ONLY GETTING INTO THE LOWER 40S FOR THE PLAINS AND 20S
FOR THE MOUNTAINS. BOTH THE NAM AND GFS ARE SHOWING INCREASED
WINDS OVER THE NE PLAINS STARTING TOMORROW AFTERNOON. GFS
CURRENTLY HAS 65KTS AT 700 MB THAT COULD TRANSLATE TO WARNING
CRITERIA. WILL CONSULT WITH THE NEXT SHIFT AND FUTURE MODEL RUNS
ON POSSIBLE ISSUANCE.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 326 PM MST SUN DEC 21 2014
NORTHEAST COLORADO REMAINS UNDER THE INFLUENCE OF A BROAD UPPER
LEVEL TROUGH CENTERED OVER NEBRASKA AND A STRONG AND COLD NWLY
FLOW MONDAY NIGHT. BANDS OF INSTABILITY AND MOISTURE MOVING DOWN
THE WEST SIDE OF THIS TROUGH SHOULD KEEP SKIES MOSTLY
CLOUDY/OVERCAST AND SNOW CHANCES IN THE FORECAST FOR THE HIGH
PLAINS OVERNIGHT. HOWEVER AREAS ALONG THE BASE OF THE FRONT RANGE
MAY ESCAPE FROM ANY SNOWFALL DUE TO THE DRYING EFFECTS OF
DOWNSLOPE FLOW OFF THE FOOTHILLS AND CHEYENNE RIDGE. IN THE HIGH
COUNTRY...SNOWFALL WILL LIKELY CONTINUE OVERNIGHT...WITH MODERATE
SNOWFALL AT TIMES ON THE HIGHER RIDGES AND NORTHWEST FACING SLOPES
ALONG THE CONTINENTAL DIVIDE. GUSTY NORTHWEST WINDS MAY ALSO
CONTINUE TO PRODUCE SOME BLOWING SNOW IN OPEN TERRAIN. WITH
SNOWFALL LETTING UP AFTER MIDNIGHT...THE WINTER STORM WARNING FOR
MTN ZONES 31...33 AND 34 WILL BE ALLOWED TO EXPIRE AT MIDNIGHT
MST. MEANWHILE STRONG NWLY FLOW ALOFT GRADUALLY MIXES DOWNWARD
OVERNIGHT AS COLD ADVECTION INCREASES. BY EARLY TUESDAY MORNING
MODELS INDICATE N-NWLY SFC WINDS GUSTING TO AROUND 40 MPH ACROSS
THE NORTHEAST CORNER OF THE STATE. WITH SEVERAL INCHES OF SNOW
COVERING THE GROUND OUT THAT WAY...GOOD BET WE/LL SEE SOME BLOWING
SNOW.
DURING THE DAY TUESDAY...MODELS SHOW THE UPPER TROUGH TRACKING
SLOWLY NEWRD AWAY FROM COLORADO WITH NLY FLOW OVER THE PLAINS
BECOMING EVEN STRONGER DURING THE DAY. MODEL WIND SPEEDS ACROSS
THE NERN CORNER IN THE 35-50KT RANGE FOR MUCH OF THE DAY.
BLOWING SNOW WILL BE A GOOD BET ESPECIALLY IN OPEN AREAS OF
LOGAN...WASHINGTON...SEDGWICK AND PHILLIPS COUNTIES WHERE SEVERAL
INCHES OF SNOW ON THE GROUND. NO HIGHLIGHTS AT THIS TIME...HOWEVER
A HIGH WIND WARNING MAY BE NECESSARY SHOULD LATER MODEL RUNS
INDICATE EVEN STRONGER WIND SPEEDS. AS FOR SNOWFALL...SHOULD SEE
AN END TO IT BY MORNING AT LOWER ELEVATION AND BY LATE AFTERNOON
IN THE HIGH COUNTRY WITH THE START OF WARMING AND DRYING ALOFT.
ON WEDNESDAY..LARGE UPPER RIDGE OVER THE GREAT BASIN NUDGES EASTWARD
OVER COLORADO CLEARING SKIES AND WARMING TEMPERATURES. COULD SEE AN
8-10DEG F WARMUP IN MOST AREAS ON WEDNESDAY. WEDNESDAY NIGHT UPPER
RIDGE SHIFTS EAST AS THE NEXT IN A SERIES OF LONG WAVE TROUGHS
SWEEPS OVER THE PACIFIC NORTHWEST. LATEST INDICATIONS...AND THEY ARE
IN BETTER AGREEMENT TODAY...SHOW THIS TROUGH TRACKING NEARLY DUE
EAST ACRS THE NORTHERN ROCKIES. MODELS SHOW THE SOUTH SIDE OF
THIS TROUGH BRUSHING NORTHERN COLORADO CHRISTMAS DAY. AS IT DOES
MTNS AND HIGH VALLEYS SHOULD SEE A SHOT OF SNOW AND GUSTY WINDS
WHILE THE PLAINS REMAIN MILD AND DRY WITH GUSTY DOWNSLOPE FLOW
OFF THE FRONT RANGE. AS THE TROUGH PASSES LATE ON THURSDAY...MODELS
SHOW A BAND OF LIGHT PRECIP ASSOCIATED WITH COLD FRONT SLIPPING
SOUTH ACROSS NORTHEAST COLORADO DURING THE EVENING HOURS. SOME
AREAS MAY SEE SNOWFALL...BUT ANY AMOUNTS SHOULD BE LIGHT. BY LATE
THAT NIGHT...DRYING SETS IN ON COLD AND GUSTY NWLY WINDS.
FRIDAY AND SATURDAY LOOK DRY BUT WITH BELOW AVERAGE TEMPERATURES.
&&
.AVIATION...(FOR THE TAFS THROUGH 06Z MONDAY EVENING)
ISSUED AT 926 PM MST SUN DEC 21 2014
STRONGER WINDS TO AROUND 35-40 KNOTS NOW NOTED WITH COLD FRONT
MOVING THROUGH GREELEY-FORT COLLINS AREA. WILL INCREASE THE NORTH
WINDS IN THE TAF WITH GUSTS TO AROUND 35 KNOTS FOR A BRIEF TIME
WITH COLD FRONT. STILL EXPECT RAIN RAIN SHOWERS WITH ILS LANDING
CONDITIONS TIL AROUND 05Z-06Z...THEN SNOW SHOWERS WITH IFR/MVFR
CEILINGS AND VISIBILITIES WITH SNOW SHOWERS. POTENTIAL FOR LOWER
VISIBILITIES OF ONE MILE OR LESS IF SHOWERS MAINTAIN THERE PRESENT
INTENSITY...WITH LOCAL SNOW ACCUMULATION UP TO AN INCH OR SO
POSSIBLE MAINLY ON GRASSY SURFACES. THOSE WOULD LIKELY BE ENDING
TOWARD 12Z AS DRIER AIR MOVES IN FROM THE NORTHWEST.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL MIDNIGHT MST MONDAY NIGHT FOR
COZ031>034.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST MONDAY NIGHT FOR
COZ030.
&&
$$
UPDATE...BARJENBRUCH
SHORT TERM...BOWEN
LONG TERM...BAKER
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
344 AM EST MON DEC 22 2014
.DISCUSSION...
...WARM/HUMID AIR MASS THROUGH WED...
...GOOD CHANCE FOR SHOWERS/STORMS WED AND WED NIGHT THEN COOLING
AND GRADUAL DRYING EXPECTED CHRISTMAS DAY...
CURRENTLY-TODAY...INCREASED SOUTHERLY WINDS PROVIDING LOW LEVEL
WARM ADVECTION...A WEAK SURFACE BOUNDARY AND SOME JET DIVERGENCE
COMBINED TO GENERATE A BAND OF CONVECTION THAT PRIMARILY AFFECTED
OUR NORTHERN AREAS. THE BOUNDARY WILL LIFT NORTH OF THE AREA BY
THIS AFTERNOON WHILE MAIN JET DIVERGENCE LIFTS WELL TO THE
NORTHEAST. THIS WILL CAUSE CONVECTIVE BAND TO MOVE AWAY FROM THE
AREA EARLY THIS MORNING.
FORECAST SOUNDINGS DO NOT LOOK VERY SUPPORTIVE FOR ADDITIONAL
AFTERNOON CONVECTION AS A WEAK SUBSIDENCE INVERSION IS INDICATED
BEHIND THE IMPULSE ALOFT. THE HRRR AND LOCAL WRF GENERATE LITTLE
TO NO CONVECTION OVER THE CENTRAL/SOUTH THIS AFTERNOON.
STILL...WITH A VERY MOIST AIR MASS...POSSIBLY A LITTLE SOLAR
INSOLATION AND SOME WEAK IMPULSES IN FAST SOUTHWEST FLOW
ALOFT...EXPECT A CHANCE OF SHOWERS AND A SLIGHT CHANCE OF
STORMS...MAINLY ACROSS NORTH AND CENTRAL SECTIONS WHERE THE
MOISTURE WILL BE HIGHEST.
TONIGHT...ANY CONVECTION THAT IS GENERATED THIS AFTERNOON WILL END
BEFORE MIDNIGHT. LOW LEVEL MOISTURE WILL BE HIGH AND MOS IS
SHOWING LOW CLOUDS AND FOG. BOUNDARY LAYER WINDS ARE FORECAST TO
BE 10 KNOTS SO WILL NOT PLAN ON WIDESPREAD DENSE FOG.
TUE-THU...GFS AND ECMWF SHOWING THE SAME PATTERN AS THEY LIFT THE
DEEPENING UPPER LEVEL LOW OVER IOWA NORTHEAST AND DEVELOP ANOTHER
LOW IN THE BASE OF THE TROUGH AS IT MOVES OKLAHOMA/TEXAS OVERNIGHT
TUESDAY INTO WEDNESDAY. BOTH MODELS SHOWING A 6 TO 12 HOUR SLOW
DOWN FROM PREVIOUS MODELS CYCLES PUTTING THE FRONT CLEARING
CENTRAL FLORIDA DURING THE DAY CHRISTMAS DAY. COOLER AIR ALOFT...-10C
TO -12C AT 500 MB...AND DISTURBANCES MOVING QUICKLY SOUTHWEST TO
NORTHEAST IN THE SOUTHWEST FLOW AHEAD OF THE TROUGH SHOULD TRIGGER
ISOLATED STORMS DURING THE TUESDAY. BOTH GFS AND ECMWF SHOW A COLD
FRONT SWEEPING ACROSS THE CENTRAL GULF OF MEXICO WEDNESDAY.
TEMPERATURES ALOFT WILL BE MARGINALLY COOL...-8C TO -10C AND MID LEVEL
DISTURBANCES WILL CONTINUE TO MOVE AROUND THE BASE OF THE UPPER
LEVEL TROUGH. THE FRONT SHOULD DROP QUICKLY ACROSS EAST CENTRAL
FLORIDA AND CLEAR THE FORECAST AREA CHRISTMAS DAY LEAVING ONLY
LINGERING SHOWERS IN SOUTHERN AREAS.
FRI-SUN...COOLER AND DRIER AIRMASS WILL BUILD IN BEHIND THE FRONT
FRIDAY THE SHIFT INTO THE ATLANTIC SATURDAY AND SUNDAY AS ANOTHER
TROUGH BEGINS DIGGING SOUTHWARD OVER THE NATIONS MIDSECTION. MID
LEVEL DISTURBANCES IN THE MOISTENING SOUTHWEST TO NORTHEAST FLOW IN
THE SOUTHWEST FLOW AHEAD OF THE TROUGH RESULTS IN VARIABLE CLOUDY
SKIES AND MINIMAL RAIN CHANCES.
&&
.AVIATION...
AREA OF SHOWERS WILL LIFT NORTH OF KLEE AND KDAB BY 12Z. NEAR
SATURATION OF THE LOW LEVELS WILL PRODUCE AREAS OF LOW CEILINGS
AND FOG THROUGH 13-14Z WITH MAINLY MVFR-IFR CONDITIONS. THIS WILL
BE MOST LIKELY FROM ABOUT KISM-KMCO-KTIX NORTHWARD. CEILINGS WILL
IMPROVE TO MVFR BY AROUND 15Z AND THEN VFR THIS AFTERNOON. THERE
IS A CHANCE FOR ADDITIONAL SHOWERS/STORMS TO FORM IN THE AFTERNOON
AND EARLY EVENING. ANOTHER ROUND OF LOW STRATUS IS EXPECTED
TONIGHT...STARTING IN THE LATE EVENING TO AROUND MIDNIGHT IN THE
NORTH AND IN THE PRE-DAWN HOURS ALONG THE SPACE/TREASURE COAST.
&&
.MARINE...
TODAY-TONIGHT...BOUNDARY WITH ITS ASSOCIATED SHOWERS AND RAIN
COOLED AIR ACROSS THE NORTHERN WATERS WILL LIFT NORTH AND PLACE
THE ENTIRE AREA IN A SOUTHERLY WIND FLOW BY AFTERNOON. SPEEDS LOOK
TO BE 10-15 KNOTS. DIURNAL INCREASE TO ABOUT 15 KNOTS SHOULD OCCUR
TONIGHT ESPECIALLY OVER THE GULF STREAM. EXPECT SCATTERED MORNING
SHOWERS AND ISOLATED STORMS NEAR/ALONG THE GULF STREAM AND A
SLIGHT CHANCE FOR STORMS TO MOVE OFF THE COAST THIS AFTERNOON AND
EVENING FROM THE CAPE NORTH.
TUE-FRI...COLD FRONT MOVING INTO THE EASTERN U.S. WILL CROSS FLORIDA
INTO LATE WED AND WED NIGHT. SOUTHERLY WINDS WILL INCREASE UP TO 20
KNOTS AHEAD OF THIS FRONT AND THEN SWITCH TO THE W/NW AS THE
BOUNDARY PASSES...REMAINING ELEVATED INTO CHRISTMAS MORNING. THESE
WINDS WILL BUILD SEAS UP TO 6 FEET OFFSHORE WEDNESDAY AND POSSIBLY
UP TO 7 FEET IN THE GULF STREAM AS THEY BECOME MORE NORTHWESTERLY
CHRISTMAS DAY. MAY NEED SMALL CRAFT ADVISORY OVERNIGHT TUESDAY AND
WEDNESDAY AS THE SOUTHERLY FLOW AHEAD OF THE UPPER LEVEL TROUGH
TIGHTENS AND WINDS INCREASE TO 20 KNOTS OR MORE. WINDS BEGIN TO
DIMINISH LATE CHRISTMAS DAY AND CONTINUE TO DIMINISH ON CHRISTMAS
NIGHT AND FRIDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 76 65 80 69 / 60 30 40 40
MCO 79 64 82 67 / 30 20 30 40
MLB 80 66 82 72 / 30 20 20 30
VRB 81 66 81 71 / 20 10 20 20
LEE 77 64 81 66 / 50 30 40 50
SFB 78 65 82 67 / 50 30 40 40
ORL 77 65 81 68 / 40 20 30 40
FPR 81 66 81 71 / 20 10 10 20
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM...LASCODY
LONG TERM....WIMMER
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
316 AM CST MON DEC 22 2014
...SHORT TERM...TODAY THROUGH TUESDAY
314 AM CST
THE MAIN CONCERNS DURING THIS PERIOD CONTINUE TO BE FOCUSED ON
RAINFALL AMOUNTS AND TIMING.
WATER VAPOR IMAGERY EARLY THIS MORNING INDICATES SEVERAL SMALLER
SCALE MID LEVEL VORT IMPULSES MOVING WITHIN THE LARGER SCALE TROUGH
ENCOMPASSING MUCH OF THE CENTRAL CONUS FROM THE ROCKIES EASTWARD TO
THE MISSISSIPPI VALLEY. ONE SUCH IMPULSE IS CURRENT SHIFTING ACROSS
THE AREA...AND THIS HAS ACTED TO SPARK OFF SOME LIGHT PRECIPITATION
ACROSS PORTIONS OF THE AREA OVER THE PAST COUPLE HOURS. MOST SURFACE
OBSERVATIONS UNDER THE RADAR ECHOS HAVE REPORTED RAIN OR DRIZZLE.
HOWEVER...WITH SURFACE TEMPERATURES HOVERING RIGHT AT FREEZING
ACROSS MUCH OF NORTHERN ILLINOIS...SOME AREAS COULD BE EXPERIENCING
SOME MINOR GLAZING. THIS INITIAL DISTURBANCE SHOULD MOVE NORTHEAST
OF THE AREA BY DAYBREAK...SO THERE WILL LIKELY BE A LULL IN THE
PRECIPITATION FOR SEVERAL HOURS THIS MORNING AFTER AROUND
DAYBREAK...THROUGH MID TO LATE MORNING. THEREAFTER...A SECOND MID
LEVEL IMPULSE...CURRENTLY NOTED ACROSS EASTERN PORTIONS OF
OKLAHOMA...WILL SHIFT NORTH-NORTHEASTWARD TOWARDS THE AREA BY THIS
AFTERNOON.
THIS SECOND DISTURBANCE WILL BE ACCOMPANIED BY A BETTER INFLUX OF
MOISTURE...ALLOWING FOR MORE WIDESPREAD RAIN DEVELOPMENT ACROSS
CENTRAL PORTIONS OF ILLINOIS AND INDIANA BY LATE MORNING...BEFORE
SHIFTING NORTHWARD ALL OF NORTHERN ILLINOIS/NORTHWESTERN INDIANA BY
EARLY THIS AFTERNOON. THEREFORE...A VERY WET AFTERNOON IS IN STORE
FOR THE AREA. IT IS STILL POSSIBILITY THAT AS THIS BACH OF PRECIPITATION
BEGINS TO ENTER FAR NORTHERN SECTIONS OF ILLINOIS LATER THIS
MORNING...THAT IT COULD ONSET AS A MIX OF SLEET...SNOW AND RAIN.
MODEL SOUNDINGS INDICATE PROFILES SPORTIVE OF SUCH FOR A SMALL WINDOW
OF TIME THROUGH AROUND MIDDAY. A SURGE OF A WARMER AND MOIST AIRMASS
WILL END THIS BY EARLY AFTERNOON AS ALL RAIN WILL BE FAVORED
AREA-WIDE.
AS WE HEAD INTO THE EVENING ANOTHER BACH OF RAINFALL IS EXPECTED TO
DEVELOP NORTHWARD ACROSS THE AREA. THIS ADDITIONAL RAINFALL WILL BE
DRIVEN BY YET ANOTHER INFLUX OF AN EVEN WARMER MORE MOIST AIRMASS
OUT AHEAD OF A CLOSING OFF MID LEVEL CIRCULATION OVER THE MID
MISSOURI VALLEY. THIS PROCESS WILL ALSO DRIVE ADDITIONAL MID LEVEL
IMPULSES NORTHEASTWARD ALONG ITS SOUTHEASTERN PERIPHERY RIGHT ACROSS
THE AREA. AT THE SURFACE...LOW PRESSURE WILL SHIFT FROM THE NORTHERN
PLAINS TO THE IOWA...MISSOURI STATE LINE BY THIS EVENING...THEN LIFT
A WARM/OCCLUDED FRONTAL BOUNDARY NORTHWARD ACROSS THE AREA BY
DAYBREAK TUESDAY. ONCE THIS FRONTAL BOUNDARY LIFTS OVER THE
AREA...AN ACCOMPANYING MID LEVEL DRY SLOT IS EXPECTED TO SHIFT OVER
THE AREA...BRINGING AN END TO MUCH OF THE RAINFALL EITHER VERY LATE
TONIGHT OR EARLY TUESDAY MORNING. THEREFORE...MUCH OF THE DAY
TUESDAY LOOKS TO BE CLOUDY...MILD AND ASIDE FROM THE POSSIBILITY FOR
SOME LINGERING DRIZZLE...MAINLY DRY.
TOTAL RAINFALL AMOUNTS WITH THIS ACTIVITY THIS AFTERNOON INTO
TONIGHT COULD RANGE BETWEEN A HALF INCH AND ONE INCH...AS SOME
PERIODS OF MODERATE RAIN ARE POSSIBLE INTO THIS EVENING AS PWATS
CREEP UP IN EXCESS OF 3/4 OF AN INCH. I HAVE ATTEMPTED TO FOCUS THE
BEST CHANCES FOR RAINFALL FROM MID TO LATE MORNING THROUGH LATER
TONIGHT ACROSS MY CENTRAL ILLINOIS COUNTIES...AND FROM AROUND MIDDAY
THROUGH TONIGHT FOR MY NORTHERN AREAS.
KJB
&&
LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
DURING THIS PERIOD THE PRIMARY FOCUS WILL BE WITH THE SECOND STORM
SYSTEM EXPECTED TO DEVELOP AND IMPACT THE GREAT LAKES REGION
CHRISTMAS EVE.
A VERY IMPRESSIVE JET CORE...IN EXCESS OF 150 KT...EXTENDS FROM THE
EASTERN PACIFIC...ONSHORE OVER THE NORTHWESTERN CONUS AT THIS
TIME. THIS JET MAX IS EXPECTED TO BE THE MAIN PLAYER IN THE
DEVELOPMENT OF A SIGNIFICANT STORM SYSTEM BY MID WEEK. MODEL
SOLUTIONS (NAM ASIDE) HAVE COME INTO SOME BETTER AGREEMENT WITH THE
SURFACE LOW. OVERALL...IT APPEARS THAT CYCLOGENESIS WILL BE INDUCED
NEAR THE CENTRAL GULF COAST BY LATE TUESDAY...THEN RACE NORTHWARD
ACROSS THE OHIO VALLEY REGION AND INTO THE CENTRAL GREAT LAKES
REGION BY CHRISTMAS EVE NIGHT. IT STILL APPEARS THAT THE SURFACE LOW
WILL DEEPEN CONSIDERABLY LATE WEDNESDAY AND INTO CHRISTMAS MORNING
AS THE UPPER LEVEL IMPULSE LOOKS TO TAKE ON A NEGATIVE TILT. MOST
OPERATIONAL GUIDANCE HINTS AT HEALTHY 15 TO 20 MB DEEPENING BETWEEN
12 UTC WEDNESDAY AND 12 UTC THURSDAY.
ALTHOUGH TWEAKS TO THE TRACK AND TIMING OF THE SYSTEM ARE STILL A
POSSIBILITY...IT APPEARS THE MAIN UNCERTAINTIES AT THIS POINT WILL BE
THE MESOSCALE DETAILS...AND HENCE WHERE THE BEST DEFORMATION BANDING
WILL OCCUR LATER IN THE DAY CHRISTMAS EVE. BOTH THE GFS AND THE
PAR GFS INDICATE A SLIGHTLY FARTHER NORTH PROGRESSION OF THE
DEFORMATION BAND ACROSS MUSH OF NORTHEASTERN ILLINOIS AND
NORTHWESTERN INDIAN WED AFTERNOON AND EVENING. IN CONTRAST THE
ECMWF...GEM AND UKMET ARE A BIT FARTHER SOUTH...MAINLY IMPACTING MY
SOUTHEASTERN CWA. OVERALL...THERE IS TYPICALLY A STRONG NORTHWESTERN
GRADIENT TO THESE DEFORMATION BANDS...SO THIS COULD LEAD TO A SHARP
CONTRAST IN PRECIPITATION AMOUNTS ACROSS MY CWA.
IT APPEARS THAT PRECIPITATION TYPE WITHIN THIS DEFORMATION BAND WOULD
LIKELY BE IN THE FORM OF SNOW. MODEL SOUNDINGS SUGGEST THAT
BOUNDARY LAYER TEMPERATURES MAY REMAIN A BIT WARM LATE WEDNESDAY AND
EVENING...BUT TYPICALLY DYNAMIC COOLING FROM STRONG FORCING FOR
ASCENT WITHIN THESE DEFORMATION BANDS LEADS TO TRANSITION TO A
PERIOD OF MODERATE TO EVEN HEAVY SNOWFALL. AT THE CURRENT TIME...I
HAVE REMAINED VERY CONSERVATIVE ON SNOW AMOUNTS OVER THE AREA...DUE
TO UNCERTAINTIES ON WHERE THIS POTENTIAL BAND OF HEAVIER PRECIP SETS UP.
HOWEVER...I WOULD NOT BE SURPRISED FOR SOME AREAS...PARTICULARLY IN MY
SOUTHERN AND EASTERN CWA TO END UP WITH SEVERAL INCHES OF
SNOW BY LATE CHRISTMAS EVE. AS SUCH...CHANGES TO SNOW AMOUNTS IS A
GOOD LIKELIHOOD.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* VFR OR BRIEF HIGHER END MVFR CIGS THIS MORNING EXPECTED TO LOWER
TO IFR THIS AFTERNOON AND POSSIBLY LIFR THIS EVENING.
* SPOTTY LIGHT RAIN/SNOW WEST/NORTHWEST OF ORD/MDW EARLY THIS
MORNING.
* RAIN DEVELOPING MIDDAY AND CONTINUING INTO TONIGHT.
* SOUTH-SOUTHEAST WINDS AROUND 10 KT BECOMING SOUTHEAST NEAR 15 KT
BY AFTERNOON.
RATZER
//DISCUSSION...UPDATED 06Z...
FORECAST AREA REMAINS ALONG SOUTHEASTERN PERIPHERY OF LOW STRATUS
WITH CIGS HAVING IMPROVED TO VFR DURING THE LATE EVENING HOURS.
COMPACT MID-LEVEL DISTURBANCE NOTED LIFTING NORTHEAST ACROSS WEST-
CENTRAL IL PRODUCING SPOTTY LIGHT PRECIP IN THE FORM OF LIGHT
RAIN OR RAIN/SNOW AND SOME PATCHY 2500-3000 FT MVFR CIGS...AND
WILL LIKELY AFFECT RFD AND POSSIBLY CHICAGO TERMINALS FOR A FEW
HOURS DURING THE PRE-DAWN HOURS. OTHERWISE...MORE STEADY RAIN IS
EXPECTED TO OVERSPREAD THE AREA MIDDAY AND CONTINUE INTO TONIGHT.
CIGS AND VSBY EXPECTED TO DETERIORATE TO IFR WITH THE RAIN EARLY
THIS AFTERNOON...AND LIKELY TO LIFR TONIGHT AS A WARM FRONT
APPROACHES.
SOUTH-SOUTHEAST WINDS 8-10 KT ARE EXPECTED TO BECOME EAST-
SOUTHEAST NEAR 15 KT BY EARLY AFTERNOON...DECREASING AND BACKING
SOUTH AGAIN TOWARD TUESDAY MORNING.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* MEDIUM CONFIDENCE IN CIGS THROUGH PERIOD.
* MEDIUM-HIGH IN GENERAL PRECIP TIMING.
* HIGH CONFIDENCE OTHER ELEMENTS.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY...MVFR CIGS LIKELY. IFR CIGS POSSIBLE...MAINLY EARLY.
WEDNESDAY...MVFR CIGS LIKELY. CHANCE OF RA/SN.
THURSDAY...CHANCE OF MVFR CIGS...MAINLY EARLY.
FRIDAY...CHANCE OF MVFR CIGS. CHANCE OF -RA/-SN
SATURDAY...MVFR CIGS LIKELY. CHANCE OF FLURRIES.
IZZI
&&
.MARINE...
233 AM CST
FORECAST FOR LAKE MICHIGAN REMAINS COMPLICATED THIS MORNING...WITH
TWO AREAS OF LOW PRESSURE EXPECTED TO BRING PERIODS OF STRONG WINDS
ACROSS THE LAKE OVER THE NEXT SEVERAL DAYS.
THE FIRST LOW WAS MOVING SOUTHEAST ACROSS THE DAKOTAS EARLY THIS
MORNING...WITH A TIGHTENING PRESSURE GRADIENT EXTENDING EAST INTO
THE WESTERN LAKES. OBSERVATION PLATFORMS ALONG THE WEST AND
NORTHWEST SHORES OF THE LAKE WERE REPORTING SOUTH WINDS IN THE 25-30
KT RANGE...WITH WINDS TO 30 KT EXPECTED TO BACK TO THE EAST AS THE
LOW MOVES TO THE IOWA-MISSOURI BORDER TONIGHT. THE LOW WILL THEN
BEGIN TO FILL AS IT TURNS NORTHEAST...LIFTING ACROSS NORTHERN LAKE
MICHIGAN LATE TUESDAY.
EXPECTATIONS ARE THAT A SECOND LOW WILL DEVELOP TO THE SOUTH ACROSS
THE TENNESSEE AND OHIO RIVER VALLEYS BY EARLY WEDNESDAY MORNING...
DEEPENING AS IT LIFTS NORTHWARD INTO THE CENTRAL GREAT LAKES REGION
BY WEDNESDAY EVENING. MODELS CONTINUE TO SHOW DIFFERENCES IN THE
EXACT TRACK AND STRENGTH OF THE LOW AS IT PASSES EAST OF LAKE
MICHIGAN...AS WELL AS NORTH AND NORTHWEST WIND SPEEDS WEDNESDAY
AFTERNOON INTO THURSDAY MORNING. AT THIS POINT...IT APPEARS THAT
WINDS OF 25-30 KT ARE LIKELY...AND POSSIBLY STILL GALES FOR A TIME
IF THE LOW DEEPENS A LITTLE FASTER. WINDS THEN LOOK TO DIMINISH AND
BACK TO THE WEST AND THEN SOUTHWEST CHRISTMAS DAY. MODELS ARE IN
BETTER AGREEMENT IN ANOTHER LOW APPROACHING AND LIFTING ACROSS THE
NORTHERN LAKES FRIDAY AND FRIDAY NIGHT.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 3 AM TUESDAY.
SMALL CRAFT ADVISORY...LMZ741-LMZ742...NOON MONDAY TO 3 AM
TUESDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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[top]
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
330 AM CST Mon Dec 22 2014
.SHORT TERM...(Today)
ISSUED AT 328 AM CST MON DEC 22 2014
Strong jet (175kts) over the Pacific Northwest digging southeast
into a deepening central Plains trof this morning will eject an
initial wave into our area today bringing rain along with mild
temperatures. Low pressure is expected to consolidate over north
central Missouri by late this afternoon and then track thru
northwest Illinois early this evening. The southerly flow in advance
of the storm system will quickly saturate the lower levels of the
atmosphere with rain overspreading the area from southwest to
northeast this morning. Some weak isentropic lift and moisture
convergence early this morning has produced some spotty light
rain/drizzle over parts of central Illinois and expect that to
continue before the stronger forcing arrives later this morning.
Models suggest the strongest lift moves into our area from mid
morning thru the early evening hours, so high POPs are warranted
over most of the forecast area today. Despite the cloud cover and
precip, mild temperatures to prevail again today with afternoon
readings in the mid to upper 40s.
&&
.LONG TERM...(Tonight through Sunday)
ISSUED AT 328 AM CST MON DEC 22 2014
Increased rain chances to categorical this evening with supporting
lift of low level jet and short waves ejecting ne from
central/southern plains into IL tonight. SPC has thunder chances
just southeast of IL. Rain chances to diminish from sw to ne
during overnight into Tue morning as energy shifts north of
central IL Tue. Appears to be a lull in rain chances Tue and Tue
evening over much of central IL with best rain chances shifting to
our north with surface low pressure over southern WI Tue afternoon
and also to our se. Mild lows tonight of 40-45F and highs Tue
range from mid 40s over IL river valley and lower 50s in southeast
IL.
00Z models still not in good agreement with development of strong
low pressure system from northwestern Gulf of Mexico and deepening
nne across the ohio river valley Wed. NAM model appears is dry over
IL Tue night and Wed but feel its low pressure track is too far east
near the foothills of the Appalachians. Will use a blend of the
ECMWF/GEM and GFS models for the storm system during midweek. Have
precipitation chances spreading back northward across central IL
overnight Tue night into Wed and diminishing from west to east by
overnight Wed night. Warm enough for rain Tue evening, then mixing
with and gradually changing to light snow later Tue night into Wed
from west to east. Deformation band of light snow accumulations
likely to set up on back side of storm system, though placement of
this band is still too difficult to pinpoint down. WPC keeps snow
accumulations less than 1 inch over central/eastern IL on
Wed/Christmas eve. Cooler highs Wed in the upper 30s to near 40F
eastern IL and will likely slip during the afternoon with increasing
WNW winds.
Christmas Day still looks dry with return of some sunshine as strong
storm system lifts into Quebec and 1025 mb surface high pressure
over gulf of mexico ridges northward into the ohio river valley.
Highs in the lower 40s Thu/Christmas Day, so any snow that does fall
Wed will likely melt.
Models have another low pressure taking a track more nw of central
IL Friday and lifting into the western Great Lakes Friday night.
Have small chances of light precipitation Fri/Fri night and then dry
for the weekend. Models showing yet another southern low pressure
system over gulf of Mexico Sat night/Sunday but for now will keep
precipitation chances south of central IL. Highs Fri in the low to
mid 40s, cool to highs in upper 20s to mid 30s this weekend.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
ISSUED AT 1133 PM CST SUN DEC 21 2014
Moisture channel satellite imagery shows vort max about Macomb
now, continuing to track to the northeast. Few sprinkles ahead of
the vort max moved to the northeast of area. HRRR model still
shows IFR cigs developing north into the central TAF sites around
15z and so timed IFR conditions coming into area accordingly. As
the upper system gets closer, lowered the vsb to IFR levels.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Shimon
LONG TERM...07
AVIATION...Goetsch
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1144 PM CST SUN DEC 21 2014
.UPDATE...
914 PM CST
WHILE THERMAL PROFILES ARE STILL A BIT TRICKY IN OUR WESTERN CWA
OVERNIGHT...FEELING IS THAT IF SOME PRECIP SNEAKS IN OVERNIGHT...SURFACE
TEMPS WOULD BE AROUND FREEZING OR POSSIBLY SLIGHTLY WARMER WHICH
WOULD MITIGATE IMPACTS SIGNIFICANTLY. MLI IS REPORTING UNKNOWN
PRECIP THIS EVENING BUT WITH A SURFACE TEMP IN THE MID 30S. WHEN
PRECIP ARRIVES IN THE MORNING IN THE WEST AND SOUTH...TEMPS SHOULD
LARGELY STILL BE ABOVE FREEZING. WHILE THE CHANCE IS NOT ZERO FOR
SOME LIGHT FZDZ OR SLEEET...CONFIDENCE IS LOW.
KMD
&&
.SHORT TERM...
246 PM CST
THROUGH TUESDAY...
TONIGHT THROUGH TUESDAY...
BROAD SFC RIDGE HAS BECOME CENTERED OVER THE NORTHEAST CONUS...AND
CONTINUES TO SLOWLY DRIFT EAST/NORTHEAST. THE GRADIENT ACROSS THE
GREAT LAKES HAS REMAINED LIGHT THIS AFTN...WITH A MAINLY SOUTHERLY
FLOW. CLOUDS REMAIN LOCKED IN ACROSS THE FORECAST AREA...WITH SOME
CLEARING JUST SOUTHEAST OF THE CWFA IN CENTRAL/NORTHERN IN. SFC
TEMPS HAVE BEEN ABLE TO WARM TO THE MID/UPR 30S...WITH DEW PTS
HOVERING AROUND 30-33 DEG. MOST THE EVENING WILL REMAIN DRY...WITH
THE WEAK MID-LVL WAVE SLIDING NORTHEAST ACROSS IOWA/WISC WITH SOME
LGT SNOW...OTHERWISE MOST OF THE FORECAST AREA SHUD REMAIN DRY THRU
THE OVERNIGHT PERIOD.
500MB VORT BEGINS TO LIFT NORTHEAST FROM THE CENTRAL PLAINS BEFORE
DAYBREAK MON...PUSHING THE MOIST CHANNEL FURTHER EAST ACROSS THE
FORECAST AREA. WITH SOUNDINGS SUGGESTING A WARM WEDGE DEVELOPING
ALOFT...P-TYPE COULD BE A CHALLENGE ARND DAYBREAK. GUIDANCE WOULD
SUGGEST TEMPS COULD BE WARM ENOUGH TO LIMIT PRECIP TO LGT
RAIN...WITH NEAR SFC TEMPS HOLDING ARND THE FREEZING MARK...SO HAVE
CONTINUED THE MENTION OF FZRA MAINLY SOUTH OF ROCKFORD. CLOSER TO
ROCKFORD THE THERMAL PROFILE IS A LITTLE MORE TRICKY AND COULD ALLOW
SOME LGT SNOW/SLEET AT THE ONSET CHANGING TO LGT RA/FZRA BEFORE
MIDDAY. THROUGHOUT THE AFTN TEMPS WILL STEADILY WARM...NEARING 40
DEG IN MOST LOCATIONS AS WARM/MOIST AIR CONTINUES TO ADVECT NORTH
ACROSS THE CWFA. MOST GUIDANCE INDICATES LGT RAIN WILL PERSIST THRU
THE AFTN/EVE HOURS...WITH THE DRY WEDGE NOT ARRIVING UNTIL CLOSER TO
DAYBREAK TUE. LOCAL SOLUTION SUGGESTS SLIGHTLY EARLIER WITH BRINGING
A TEMPORARY END TO THE PRECIP...JUST AFT MIDNIGHT MON NGT.
TEMPS OVERNIGHT WILL REMAIN MILD IN THE UPR 30S/NEAR 40. WITH THE
TROUGH TAKING ON A NEGATIVE TILT MIDDAY TUE...THE SFC LOW WILL BE
WRAPPED UP ACROSS CENTRAL WISC. GUIDANCE HAS BOUNCED AROUND POSSIBLY
KEEPING EITHER DRY/LOW CHC POPS OVER NORTHERN IL/NORTHWEST IN
TUE/TUE AFTN...BUT HAVE OPTED TO HOLD ONTO A SLT CHC OF RAIN. WITH
WARM AIR CONTINUING TO ADVECT NORTH...SFC TEMPS COULD PUSH INTO THE
MID/UPR 40S WITH A FEW LOCATIONS IN THE SOUTHEAST REACHING 50 DEG.
BY TUE EVENING THE TROUGH AXIS IS PROGGED TO EJECT ANOTHER SFC LOW
ACROSS THE GULF STATES...THEN QUICKLY LIFT NORTH ACROSS THE TENN
VALLEY LATE TUE NGT. MOISTURE WILL FILL BACK IN ACROSS THE FORECAST
AREA TUE NGT...WITH RAIN BECOMING MIXED WITH SNOW OVERNIGHT. TEMPS
WILL SLOWLY COOL...SO THE PERIOD OF RAIN/SNOW MIX COULD LINGER
AWHILE.
BEACHLER
&&
.LONG TERM...
246 PM CST
WEDNESDAY THROUGH SUNDAY...
MID-WEEK ENSEMBLES CONTINUE TO PROG A SLIGHT STRENGTHENING TO THE
DOWNSTREAM RIDGE OVER THE CANADIAN MARITIME...WHICH WILL LIMIT HOW
FAR EAST THE SECONDARY LOW WILL PROGRESS. OPERATIONAL SOLUTIONS
CONTINUE TO LIFT THE STRENGTHENING LOW NORTH ACROSS THE OHIO VALLEY
WED AFTN...AND QUICKLY NORTH OF LAKE HURON BY LATE WED NGT. WRAP
AROUND MOISTURE AND COOLER AIR WILL BRING SOME LGT SNOW TO NORTHERN
IL WED.
FOR CHRISTMAS DAY THE DOWNSTREAM RIDGE WILL BEGIN TO
WEAKEN...ALLOWING THE MID-LVL TROUGH TO BECOME PROGRESSIVE AND PUSH
EAST. THIS SHUD BRING AN END TO THE LGT SNOW/FLURRIES BY DAYBREAK.
TEMPS SHUD RETURN TO THE MID/UPR 30S...ALONG WITH PERHAPS SOME
BREAKS IN THE CLOUD COVER BY THE AFTN. MID-LVL HEIGHTS SHUD START TO
INCREASE THUR NGT/FRI...HOWEVER THIS LOOKS TO BE SHORT-LIVED AS YET
ANOTHER TROUGH IS PROGGED TO DIG SOUTH FROM THE CANADIAN ROCKIES
INTO THE NORTHERN PLAINS. THE STRONGER PUSH OF COLDER AIR LOOKS TO
ARRIVE SAT...ALTHOUGH THIS MAY ONLY BE A SHORT DURATION WITH THE
SEMI-ZONAL PATTERN SETTING UP FOR THE SECOND HALF OF THE WEEKEND.
BEACHLER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* VFR OR BRIEF HIGHER END MVFR CIGS THIS MORNING EXPECTED TO LOWER
TO IFR THIS AFTERNOON AND POSSIBLY LIFR THIS EVENING.
* SPOTTY LIGHT RAIN/SNOW WEST/NORTHWEST OF ORD/MDW EARLY THIS
MORNING.
* RAIN DEVELOPING MIDDAY AND CONTINUES INTO TONIGHT.
* SOUTH-SOUTHEAST WINDS AROUND 10 KT BECOMING SOUTHEAST NEAR 15 KT
BY AFTERNOON.
RATZER
//DISCUSSION...UPDATED 06Z...
FORECAST AREA REMAINS ALONG SOUTHEASTERN PERIPHERY OF LOW STRATUS
WITH CIGS HAVING IMPROVED TO VFR DURING THE LATE EVENING HOURS.
COMPACT MID-LEVEL DISTURBANCE NOTED LIFTING NORTHEAST ACROSS WEST-
CENTRAL IL PRODUCING SPOTTY LIGHT PRECIP IN THE FORM OF LIGHT
RAIN OR RAIN/SNOW AND SOME PATCHY 2500-3000 FT MVFR CIGS...AND
WILL LIKELY AFFECT RFD AND POSSIBLY CHICAGO TERMINALS FOR A FEW
HOURS DURING THE PRE-DAWN HOURS. OTHERWISE...MORE STEADY RAIN IS
EXPECTED TO OVERSPREAD THE AREA MIDDAY AND CONTINUE INTO TONIGHT.
CIGS AND VSBY EXPECTED TO DETERIORATE TO IFR WITH THE RAIN EARLY
THIS AFTERNOON...AND LIKELY TO LIFR TONIGHT AS A WARM FRONT
APPROACHES.
SOUTH-SOUTHEAST WINDS 8-10 KT ARE EXPECTED TO BECOME EAST-
SOUTHEAST NEAR 15 KT BY EARLY AFTERNOON...DECREASING AND BACKING
SOUTH AGAIN TOWARD TUESDAY MORNING.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM CONFIDENCE IN CIGS THROUGH PERIOD.
* MEDIUM-HIGH IN GENERAL PRECIP TIMING.
* HIGH CONFIDENCE OTHER ELEMENTS.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY...MVFR CIGS LIKELY. IFR CIGS POSSIBLE...MAINLY EARLY.
WEDNESDAY...MVFR CIGS LIKELY. CHANCE OF RA/SN.
THURSDAY...CHANCE OF MVFR CIGS...MAINLY EARLY.
FRIDAY...CHANCE OF MVFR CIGS. CHANCE OF -RA/-SN
SATURDAY...MVFR CIGS LIKELY. CHANCE OF FLURRIES.
IZZI
&&
.MARINE...
204 PM CST
SMALL CRAFT ADVISORY...KEPT THE CURRENT SMALL CRAFT AS IS AND
EXPANDED IT TWO ZONES SOUTH THROUGH CALUMET HARBOR. WAVES WILL
BECOME HAZARDOUS OVERNIGHT NORTH OF WILMETTE HARBOR AND THEN WINDS
AND WAVES WILL BECOME HAZARDOUS TOMORROW AFTERNOON. MARGINAL SMALL
CRAFT CONDITIONS ARE POSSIBLE ALONG THE INDIANA NEARSHORE WATERS AND
DO NOT HAVE ENOUGH CONFIDENCE TO ISSUE A SMALL CRAFT ADVISORY AT
THIS TIME.
HIGH PRESSURE IS OVER THE EAST COAST WHILE THE NEXT LOW IS OVER THE
NORTHERN PLAINS. SOUTH WINDS HAVE INCREASED TO 15-25 KT ACROSS THE
LAKE AND WILL CONTINUE TO INCREASE TO 30 KT THIS AFTERNOON. WINDS
BECOME SOUTHEAST TOMORROW AS THE LOW MOVES OVER THE EASTERN PLAINS
AND WEAKENS. THE LOW THEN WEAKENS OVER WISCONSIN TUESDAY AFTERNOON
THROUGH TUESDAY NIGHT. WINDS WEAKEN ACROSS THE LAKE MONDAY NIGHT AND
BECOME WEST TO NORTHWEST 10-15 KT TUESDAY NIGHT. A SECOND LOW FORMS
OVER THE SOUTHERN MISSISSIPPI VALLEY TUESDAY NIGHT AND QUICKLY
DEEPENS AS IT MOVES NORTH. GUIDANCE DIFFERS ON HOW FAR TO OUR EAST
THE LOW WILL PASS...BUT THINKING IT WILL BE OVER THE EASTERN GREAT
LAKES. GUIDANCE HAS ALSO BACKED OFF ON WIND SPEEDS BEHIND THE LOW
AND WILL ONLY CARRY OCCASIONAL GALES IN THE GLF AT THIS TIME. SO
HAVE WEST TO NORTHWEST WINDS INCREASING TO 30 KT WEDNESDAY NIGHT.
THE BEST WINDOW FOR GALES WOULD BE LATE WEDNESDAY NIGHT. THE LOW
THEN CONTINUES NORTHEAST INTO QUEBEC THURSDAY AND HAVE SOUTHWEST
WINDS DECREASING THURSDAY. ANOTHER LOW SLIDES ACROSS THE PLAINS
THURSDAY AFTERNOON AND WILL IMPACT THE LAKE FRIDAY. GUIDANCE
DIFFERS ON HOW STRONG THE LOW WILL BE WHEN IT MOVES OVER THE
LAKE...SO HAVE LOW CONFIDENCE IN THE FORECAST LATE NEXT WEEK.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 3 AM TUESDAY.
SMALL CRAFT ADVISORY...LMZ741-LMZ742...NOON MONDAY TO 3 AM
TUESDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1137 PM CST Sun Dec 21 2014
.UPDATE...
ISSUED AT 904 PM CST SUN DEC 21 2014
Moisture channel satellite imagery depicts minor vort max near
Quincy moving to the northeast. Radar showing development of some
very light pcpn ahead of the vort max over north central IL.
Updated the grids for sprinkles for few hours late this evening.
Clouds have come back into the region with the wave.
&&
.SHORT TERM...(Tonight)
ISSUED AT 256 PM CST SUN DEC 21 2014
Low pressure currently over southern Alberta will track into eastern
South Dakota by 12z Mon. Ahead of the system, a tightening pressure
gradient will produce southeasterly winds of 10 to 15 mph across
central Illinois tonight. Due to these sustained winds and a partly
to mostly cloudy sky, overnight low temperatures will be a few
degrees warmer than last night and several degrees warmer than
either the MAV or MET guidance. Lows will once again be coolest
across the SE KILX CWA where skies will initially be mostly clear
and warmest across the W/NW where clouds will hold firm. Readings
will range from the upper 20s near the Indiana border to the middle
30s along/west of I-55. Any precipitation associated with the
approaching system will remain west of the Mississippi River until
later Monday morning, as forecast soundings remain dry through 12z.
&&
.LONG TERM...(Monday through Sunday)
ISSUED AT 256 PM CST SUN DEC 21 2014
Beginning to look like a good news/bad news scenario setting up with
the storm system expected to impact central and southeast Illinois
from Monday into Christmas Eve. If recent model trends hold, the
good news will be that significant weather related travel impacts
are not expected on Christmas Eve in the area. The bad news, for
some, would be that a "White Christmas" is looking less likely
locally.
We are still looking at active weather the next few days as a
complex, slow moving, storm system impacts the area. A 160+ kt
upper-level jet crashing into the Pacific NW & northern Rockies will
continue to amplify troffing over the middle of the nation, a trof
that will be with us for a few days.
A closed upper low is expected to develop over the northern
Plains/upper Midwest Monday, nearly vertically stacked with an
associated surface low. The WAA/isentropic lift ahead of these lows
will be accompanied by a periods of rainfall from Monday into Monday
night. Then, another vigorous piece of upper energy will round the
base of the mean trof Tuesday into Wednesday, accompanied by the
development of another surface low. This second low will become the
dominant low, with the first low expected to dissipate. A dry slot
is progged to wrap around the initial upper low, no doubt aided by
the secondary wave intercepting much of the deeper moisture. This
dry slot may result in much of Tuesday/Tuesday night ending up dry
across the northwest 1/2 of the forecast area, certainly drier than
it looked yesterday. The southeast 1/2 of the forecast area should
see rain chances persisting Tuesday and Tuesday night, as this area
will be closer to the track of the secondary wave. The remaining
precipitation will change over to light snow on Christmas Eve, but
model agreement is strengthening and this suggests that snowfall
will not be a significant impact across the forecast area.
Mostly dry conditions are expected by Christmas Day as the system
heads northeast into Canada. Another, much weaker, system is progged
to impact the area by Friday. However, guidance suggests that this
system will have minimal moisture to work with until it moves east
of the forecast area. This is because there will not have been much
time for the atmosphere to recover from the cold/dry advection in
the wake of the midweek system. So, only have a slight chance of
rain and/or snow for Friday into Friday night. While temperatures
will be above normal for much of this week, they will trend below
normal behind Friday`s system.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
ISSUED AT 1133 PM CST SUN DEC 21 2014
Moisture channel satellite imagery shows vort max about Macomb
now, continuing to track to the northeast. Few sprinkles ahead of
the vort max moved to the northeast of area. HRRR model still
shows IFR cigs developing north into the central TAF sites around
15z and so timed IFR conditions coming into area accordingly. As
the upper system gets closer, lowered the vsb to IFR levels.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Goetsch
SHORT TERM...Barnes
LONG TERM...Bak
AVIATION...Goetsch
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
439 AM EST MON DEC 22 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 425 AM EST MON DEC 22 2014
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SW FLOW ALOFT OVER
THE WRN GREAT LKS TO THE E OF A DEEPENING UPR TROF IN THE CENTRAL
CONUS CAUSED BY SHRTWVS DIGGING SEWD IN NW FLOW ALOFT E OF UPR RDG
ALONG THE W COAST. SHRTWV RESPONSIBLE FOR THE SN ON SUN EVNG IS
LIFTING NEWD THRU NW ONTARIO. AS THE ACCOMPANYING STRONGER DYNAMIC
FORCING SHIFTS TO THE NE...IR STLT IMAGERY SHOWS WARMING CLD TOP
TEMPS AS THE COMMA TAIL MSTR BAND SHIFTS TO THE E. ALTHOUGH RADAR
SHOWS THE HEAVIER PCPN IS FOLLOWING OFF TO THE NE...SOME PATCHY
ECHOES REMAIN OVER MUCH OF THE CWA. COMPOSITE RADAR INDICATES
GENERALLY LIGHT MIXED PCPN STRETCHES OFF TO THE SW THRU MUCH OF THE
NW HALF OF WI...WHERE MODELS SHOW AN AXIS OF WEAKER DEEP LYR QVECTOR
CNVGC. SFC OBS INDICATE LOWER SFC DEWPTS OVER NRN LOWER MI...UPWIND
OF THE E HALF OF THE CWA.
MAIN FCST CONCERNS TODAY FOCUS ON DIMINISHING PCPN TRENDS. FOCUS FOR
TNGT SHIFTS TO TIMING THE ARRIVAL OF ANOTHER AREA OF SN/MIXED PCPN
AS ANOTHER SHRTWV LIFTS NEWD OUT OF DEEPENING UPR TROF THAT CAUSES A
CLOSED H5 LO TO DEVELOP IN THE CENTRAL PLAINS.
TODAY...EXPECT SOME GENERALLY LGT SN/MIXED WITH RA TO IMPACT MAINLY
THE W HALF OF THE CWA THRU THIS MRNG AWAY FM THE DRIER NEAR SFC AIR
ADVECTING INTO THE ERN ZNS AND UNDER LINGERING BUT SLOWLY FADING
DEEP LYR QVECTOR CNVGC AS SHRTWV RDG APRCHS FM THE SW. DURING THE
AFTN...ARRIVAL OF DRIER AIR ALOFT FM THE S WITHIN THE NVA SHOULD END
ANY LINGERNING LARGE SCALE PCPN. BUT CONCERNED SOME SN GRAINS/
FREEZING DZ/DZ WL LINGER OVER MAINLY THE CENTRAL CWA WITH UPSLOPE SE
FLOW OFF LK MI. THIS POTENTIAL WL BE LIMITED BY ADVECTION OF LOWER
H95-9 SPECIFIC HUMIDITY NOW OVER NRN LOWER MI...ESPECIALLY OVER THE
E HALF AND BY LATE AFTN EVEN OVER THE CENTRAL. EXPECT TEMPS TO TOP
OUT ABOVE FREEZING EVERYWHERE...SO ANY FREEZING DZ SHOULD END BY
NOON OR SO.
TNGT...AS AREA OF SGNFT DEEP LYR QVECTOR CNVGC/DEEP ISENTROPIC
ASCENT/UPR DVGC IN ADVANCE OF SHRTWV LIFTING NE TOWARD THE GREAT LKS
OVERSPREADS THE AREA...EXPECT PCPN TO DEVELOP OVER THE SCENTRAL BY
MIDNGT AND THEN SPREAD TO OVER ALL THE KEWEENAW BY 12Z TUE. PER NCEP
PREFERENCE...TENDED TOWARD THE 00Z NAM FOR FCST DETAILS. THIS MODEL
GENERATES ABOUT 0.25 INCH OF TOTAL QPF AT MENOMINEE BY 12Z TUE.
PTYPE IS A CONCERN. WHILE THE NAM FCST SDNG FOR MENOMINEE INDICATES
MAINLY RA FOR THAT LOCATION...MODEL SDNGS/H100-85 THKNS INDICATE
AREAS AWAY FM LK MI WL SEE MAINLY SN THRU 12Z TUE. ARRIVAL OF LLVL
DRY AIR TODAY THAT WL ENHANCE NEAR SFC EVAPORATIVE COOLING AND
BACKING NEAR SFC FLOW TOWARD THE ENE THAT WL CUTOFF THE ARRIVAL OF
WARMER AIR APPEAR TO BE THE REASON THE LLVL TEMPS TREND COLD ENUF
FOR MAINLY SN EXCEPT NEAR LK MI. SN/WATER RATIOS WL BE LIMITED BY
RELATIVELY HI/THIN DGZ...SO AN INCH OR TWO OF SN WL LIKELY
ACCUMULATE BY SUNRISE OVER MUCH OF THE SE HALF OF THE CWA TO THE NW
OF THE RA/SN LINE.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 438 AM EST MON DEC 22 2014
...WIDESPREAD MODERATE SNOW ON TUESDAY...
ONE PRIMARY CHANCE FOR ACCUMULATING SNOW OVER ALL OF CWA IN THE LONG
TERM ON TUESDAY BUT CANNOT RULE OUT MORE SNOW CHIRSTMAS EVE FOR
EASTERN CWA AS THE ON AGAIN OFF AGAIN LOW PRESSURE SYSTEM IS STILL
AROUND IN LATEST MODELS. ANOTHER SYSTEM MAY IMPACT REGION WITH SWATH
OF SNOW FRIDAY INTO SATURDAY...BUT LACK OF CONTINUITY FM THE MODELS
LIMITS CONFIDENCE IN THAT PART OF FORECAST ATTM.
EVOLVING LOW PRESSURE SYSTEM MOVING OUT OF THE PLAINS TUESDAY INTO
WEDNESDAY APPEARS MORE LIKE RECENT RUNS OF ECMWF. QUESTION IS HOW
FAR EAST THE MID-LEVEL AND SFC LOWS REACH ON TUESDAY AS THAT IMPACTS
DRY SLOT AND PRECIP INTENSITY...ESPECIALLY OVER THE SOUTHERN PART OF
CWA. BLEND OF NAM/SREF SUPPORTED BY NCEP AND LOOKED LIKE 12Z ECMWF.
PRIMARY SHORTWAVE AND SFC LOW MOVE TO EASTERN IOWA BY 12Z TUESDAY
AND LIFT ACROSS EASTERN WISCONSIN ON TUESDAY AFTN. CIRCULATION AROUND
SFC-H85 LOWS PULLS H7 MIXING RATIOS OVER 3G/KG NORTH OF THE LOWS OVER
MAJORITY OF UPR MICHIGAN. PER GARCIA METHOD WITH NO PTYPE
CONSIDERATIONS THAT WOULD FAVOR 3 INCHES OF SNOW IN 6 HRS. BLEND OF
FAVORED QPFS POINT TO 0.30-0.50 INCH OF LIQUID EQUIVALENT OVER MOST
CWA...WITH HIGHER AMOUNTS OVER 0.50 INCH OVER FAR WEST AND SCNTRL.
TROUBLE IS 00Z ECMWF TRENDED EAST WITH SFC LOW AND HAS DRY SLOT INTO
SCNTRL...REALLY CUTTING ITS PRECIP THERE.
PTYPE ALSO AN ISSUE...UNFORTUNATELY. SOUNDINGS FM NAM KEEP BLYR
COOL...WITH ONLY SURE CHANGE TO RAIN AT MNM WITH ENE FLOW OFF BAY OF
GREEN BAY. ENE WINDS WOULD LEAD TO COOLING TO PERSIST AT KESC AND
KISQ. GFS SIMILAR WHILE GEM-REGIONAL IS MUCH WARMER/WESTWARD WITH
1000-850MB THICKNESSES OVER 1305M. SINCE WINDS ARE BACKING AND OFF
LAND IN LOW-LAYERS WILL FAVOR COOLER IDEA OFFERED BY NAM/GFS IN THE
MORNING BUT WILL BRING MORE GEM IDEA IN THE AFTN AS SFC LOW EDGES
CLOSER TO THE AREA FM THE SOUTH. RESULT WILL BE RAIN/SNOW MIX OVER
SCNTRL UPR MICHIGAN ALONG BAY OF GREEN BAY...WITH SNOW ELSEWHERE
INTO EARLY AFTN...THEN GO FOR A MIX OF RAIN AND SNOW OVER MOST OF
THE EAST HALF CWA BY MID AFTN. NAM SOUNDINGS SHOW THE SNOW MAY LAST
THROUGH THE DAY OVER MOST OF THE WEST HALF OF CWA AND EVEN FOLLOWING
GEM THICKNESSES QPF THAT OCCURS THERE IN THE MORNING WOULD STAY ALL
SNOW. OVERALL...WILL LEAN TOWARD MOST SNOW OVER WEST HALF. SOUNDINGS
MAINTAIN LOOK OF ELEVATED NARROW DGZ AND TEMPS WARMER THAN -8C
BLO...SO LOW SLR/S...PROBABLY AROUND 10:1. BY LATE TUESDAY
AFTN...EXPECT TOTAL SNOWFALL OVER 4 INCHES OVER MOST OF THE WEST
HALF OF THE CWA...MAYBE PUSHING TOWARD 6 INCHES OVER INTERIOR WEST.
CLOSER TO LK SUPERIOR OVR NCNTRL WHERE ENE WINDS PROVIDE FLOW OF
LAKE MODIFIED WARMING...EXPECT SNOW TOTALS TO BE HELD DOWN. CONTINUED
TO INCREASE POPS TO CATEGORICAL. IT WILL SNOW. ONLY THING THAT
TEMPERS CONFIDENCE ON ISSUING 3RD PERIOD ADVY IS INCONSISTENCIES IN
WHERE THE HIGHER QPF IS ON MODELS. WILL OPT FOR A SPECIAL WEATHER
STATEMENT AND LET DAYSHIFT GET SOME MORE DATA BEFORE MAKING FINAL
CALL ON HEADLINE.
BULK OF PRECIP WILL BE DONE BY WEDNESDAY EVENING. 00Z NAM WAS QUITE
EMPHATIC WITH DEFORMATION ZONE OF LINGERING SNOW OVER THE WEST CWA
BUT WAS NOT SUPPORTED IN ITS INTENSITY BY ANY OTHER GUIDANCE. 06Z
NAM IS NOT AS BULLISH. THOUGH SOME LGT SNOW COULD CONTINUE AS AN
AREA OF MID LEVEL FGEN/DEFORMATION WILL BE REINFORCED BY WEAK TROWAL.
EVEN THIS AREA OF SNOW SHOULD DIMINISH TO LGT SNOW/FLURRIES LATE ON
TUESDAY NIGHT. FARTHER EAST...SOUNDINGS SIGNAL POSSIBLE DRIZZLE OR
FREEZING DRIZZLE AND FOG AS MID-LEVEL DRYING LEAVES MOIST LOW-LEVELS
WITH TEMPS MAINLY WARMER THAN -7C. CARRIED SLIGHT CHANCE POPS FOR
RAIN/SNOW...BUT THIS MAY NEED TO BE CONVERTED TO DZ/FOG WITH LATER
FORECASTS.
MODELS CONTINUE TO HAVE FUN WITH THE CHRISTMAS EVE SYSTEM AFFECTING
THE GREAT LAKES. AFTER BACKING AWAY COMPLETELY 24 HR AGO...MOST OF
THE MODELS CAME BACK TO SHOWING A STRONG LOW LIFTING NORTHWARD OVER
THE CNTRL GREAT LAKES WITH THE RUNS ON SUNDAY. THAT IS WHERE WE
REMAIN FOR MOST PART NOW...WITH ALL BUT THE GEM-GLOBAL AND PARALLEL
GFS INDICATING THIS SYSTEM MISSES UPR MICHIGAN. KEPT SMALL CHANCES
IN OVER FAR EAST...VCNTY OF LUCE COUNTY...BUT OTHERWISE KEPT THE CWA
VOID OF ANY POPS FM THE SYSTEM. HAVE SOME SMALL CHANCE POPS OVER THE
WEST HALF ON CHRISTMAS EVE DAY...BUT THIS IS GENERALLY DUE TO SOME
SIMBLANCE OF THE LINGERING DEFORMATION AREA FM THE TUESDAY SYSTEM
THAT WILL ONLY BE SLOWLY UNRAVELING OVER THE EAST PART OF CWA ON
WEDNESDAY.
INTO CHRISTMAS AND BEYOND...RAN WITH CONSENSUS. COULD SEE SOME LGT
LK EFFECT FOR WNW-NW FLOW AREAS ON CHRISTMAS THOUGH H85 TEMPS NEAR
-10C ARE ONLY MARGINAL FOR PURE LES. WOULD NEED SOME ADDITIONAL
LARGE SCALE SUPPORT TO RESULT IN BETTER CHANCES OF LES VIA LAKE
ENHANCEMENT. AS LONG AS THE CNTRL GREAT LAKES LOW DOES NOT COME ANY
FARTHER WEST...WILL NOT BE VERY WINDY EITHER. HIGHS ON CHRISTMAS TOP
OUT ABOVE NORMAL...WITH LOW TO MID 30S EXPECTED. AS ALLUDED TO
EARLIER...ANOTHER CLIPPER TYPE SYSTEM COULD SPREAD SOME LGT SNOW TO
THE AREA ON FRIDAY. UNCERTAINTY AND CONSISTENCY IN THAT IDEA BOTH
ARE HIGH...SO CHANCE POPS UNTIL IT GETS MORE REFINED. AT THE MOST
COULD SEE MODERATE SNOW AMOUNTS. IDEA OF COLDER WEATHER WITH LK
EFFECT STILL ON TRACK FOR THE WEEKEND. MOISTURE IS A QUESTION THOUGH
SO EVEN THOUGH H85 TEMPS FALL DOWN BLO -15C ON SUNDAY...EVEN
MODERATE LK EFFECT SNOW IS NOT A DONE DEAL YET. COOLER TEMPS WILL BE
NOTICABLE THOUGH AFTER THE RATHER MILD CHRISTMAS WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1236 AM EST MON DEC 22 2014
LIGHT/MODERATE SNOW CONTINUES ACROSS THE AREA UNDER A SOUTH FLOW OF
MOIST LLVL AIR WITH CONDITIONS RANGING FROM LIFR/VLIFR AT KCMX TO
MVFR AT KIWD. EXPECT IMPROVING CONDITIONS AT KCMX AND KSAW TO HIGH
END IFR LATE TONIGHT AND THEN TO MVFR LATE MON MORNING AS DRIER AIR
MOVES IN FM THE SOUTH. CONDITIONS WILL REMAIN MVFR THROUGH THE PD AT
KIWD AS DOWNSLOPE SOUTH WINDS SHOULD LIMIT LOWER CIGS AND VSBY
RESTRICTIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 425 AM EST MON DEC 22 2014
SSE WINDS UP TO 25-30 KTS OVER MAINLY THE E HALF OF LK SUPERIOR WILL
PERSIST THRU TODAY BUT THEN BACK TO THE E TONIGHT AND THEN THE NE ON
TUE AS A LO PRES SYSTEM MOVES NE FROM THE CENTRAL PLAINS TO OVER
LAKE MICHIGAN BY LATE IN THE DAY ON TUE. SINCE THIS LO WILL SLOWLY
WEAKEN AS IT MOVES TO THE NE...THE NE WINDS WILL FALL UNDER 20 KTS
ON TUE NIGHT. SINCE THE LATEST GUIDANCE INDICATES THE NEXT DEEPER LO
WILL TRACK N FARTHER TO THE E ON WED...A WEAKER PRES GRADIENT/N WIND
UNDER 20 KTS WILL DOMINATE ON WED. YET ANOTHER LO PRES MAY MOVE NE
FROM THE CENTRAL PLAINS LATE IN THE WEEK. AT THIS TIME...WINDS UNDER
25 KTS ARE EXPECTED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...JLA
AVIATION...VOSS
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
430 AM EST MON DEC 22 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 425 AM EST MON DEC 22 2014
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SW FLOW ALOFT OVER
THE WRN GREAT LKS TO THE E OF A DEEPENING UPR TROF IN THE CENTRAL
CONUS CAUSED BY SHRTWVS DIGGING SEWD IN NW FLOW ALOFT E OF UPR RDG
ALONG THE W COAST. SHRTWV RESPONSIBLE FOR THE SN ON SUN EVNG IS
LIFTING NEWD THRU NW ONTARIO. AS THE ACCOMPANYING STRONGER DYNAMIC
FORCING SHIFTS TO THE NE...IR STLT IMAGERY SHOWS WARMING CLD TOP
TEMPS AS THE COMMA TAIL MSTR BAND SHIFTS TO THE E. ALTHOUGH RADAR
SHOWS THE HEAVIER PCPN IS FOLLOWING OFF TO THE NE...SOME PATCHY
ECHOES REMAIN OVER MUCH OF THE CWA. COMPOSITE RADAR INDICATES
GENERALLY LIGHT MIXED PCPN STRETCHES OFF TO THE SW THRU MUCH OF THE
NW HALF OF WI...WHERE MODELS SHOW AN AXIS OF WEAKER DEEP LYR QVECTOR
CNVGC. SFC OBS INDICATE LOWER SFC DEWPTS OVER NRN LOWER MI...UPWIND
OF THE E HALF OF THE CWA.
MAIN FCST CONCERNS TODAY FOCUS ON DIMINISHING PCPN TRENDS. FOCUS FOR
TNGT SHIFTS TO TIMING THE ARRIVAL OF ANOTHER AREA OF SN/MIXED PCPN
AS ANOTHER SHRTWV LIFTS NEWD OUT OF DEEPENING UPR TROF THAT CAUSES A
CLOSED H5 LO TO DEVELOP IN THE CENTRAL PLAINS.
TODAY...EXPECT SOME GENERALLY LGT SN/MIXED WITH RA TO IMPACT MAINLY
THE W HALF OF THE CWA THRU THIS MRNG AWAY FM THE DRIER NEAR SFC AIR
ADVECTING INTO THE ERN ZNS AND UNDER LINGERING BUT SLOWLY FADING
DEEP LYR QVECTOR CNVGC AS SHRTWV RDG APRCHS FM THE SW. DURING THE
AFTN...ARRIVAL OF DRIER AIR ALOFT FM THE S WITHIN THE NVA SHOULD END
ANY LINGERNING LARGE SCALE PCPN. BUT CONCERNED SOME SN GRAINS/
FREEZING DZ/DZ WL LINGER OVER MAINLY THE CENTRAL CWA WITH UPSLOPE SE
FLOW OFF LK MI. THIS POTENTIAL WL BE LIMITED BY ADVECTION OF LOWER
H95-9 SPECIFIC HUMIDITY NOW OVER NRN LOWER MI...ESPECIALLY OVER THE
E HALF AND BY LATE AFTN EVEN OVER THE CENTRAL. EXPECT TEMPS TO TOP
OUT ABOVE FREEZING EVERYWHERE...SO ANY FREEZING DZ SHOULD END BY
NOON OR SO.
TNGT...AS AREA OF SGNFT DEEP LYR QVECTOR CNVGC/DEEP ISENTROPIC
ASCENT/UPR DVGC IN ADVANCE OF SHRTWV LIFTING NE TOWARD THE GREAT LKS
OVERSPREADS THE AREA...EXPECT PCPN TO DEVELOP OVER THE SCENTRAL BY
MIDNGT AND THEN SPREAD TO OVER ALL THE KEWEENAW BY 12Z TUE. PER NCEP
PREFERENCE...TENDED TOWARD THE 00Z NAM FOR FCST DETAILS. THIS MODEL
GENERATES ABOUT 0.25 INCH OF TOTAL QPF AT MENOMINEE BY 12Z TUE.
PTYPE IS A CONCERN. WHILE THE NAM FCST SDNG FOR MENOMINEE INDICATES
MAINLY RA FOR THAT LOCATION...MODEL SDNGS/H100-85 THKNS INDICATE
AREAS AWAY FM LK MI WL SEE MAINLY SN THRU 12Z TUE. ARRIVAL OF LLVL
DRY AIR TODAY THAT WL ENHANCE NEAR SFC EVAPORATIVE COOLING AND
BACKING NEAR SFC FLOW TOWARD THE ENE THAT WL CUTOFF THE ARRIVAL OF
WARMER AIR APPEAR TO BE THE REASON THE LLVL TEMPS TREND COLD ENUF
FOR MAINLY SN EXCEPT NEAR LK MI. SN/WATER RATIOS WL BE LIMITED BY
RELATIVELY HI/THIN DGZ...SO AN INCH OR TWO OF SN WL LIKELY
ACCUMULATE BY SUNRISE OVER MUCH OF THE SE HALF OF THE CWA TO THE NW
OF THE RA/SN LINE.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 303 PM EST SUN DEC 21 2014
LONG TERM SHIFT CONTINUES TO BE BUSY THROUGHOUT...BUT IT DOES APPEAR
THAT THE WED-THU STORM IS LESS LIKELY.
A SERIES OF SHORTWAVE TROUGHS WILL MOVE INTO THE CENTRAL CONUS THIS
WEEK...INTENSIFYING AN UPPER TROUGH ALSO OVER THE CENTRAL CONUS
THROUGH MID-WEEK. BY 00Z TUE...MODELS SHOW THAT THE TROUGH HAS
STRENGTHENED TO A CLOSED LOW OVER ERN IA. A LARGE AREA OF PRECIP
WILL EXIST JUST SW OF THE CWA ALONG AND AHEAD OF A SHORTWAVE TROUGH
ROTATING AROUND THE UPPER LOW AND IN AN AREA OF UPPER LEVEL
DIFFLUENCE. LIGHT PRECIP WILL MOVE IN MON NIGHT...WITH THE HEAVIEST
PRECIP EXPECTED TUE MORNING AS YET ANOTHER SHORTWAVE ROTATES AROUND
THE LOW. MODELS VARY IN THE AMOUNT OF QPF...THE 12Z/21 GFS IS ON THE
HIGH SIDE SHOWING WIDESPREAD AMOUNTS AROUND 0.45 INCHES TUE
MORNING...THE 12Z/21 NAM IS 6 HOURS FASTER AND SHOWS SLIGHTLY LESS
QPF...AND THE 00Z/21 ECMWF SHOWS ABOUT HALF THE QPF OF THE GFS. WARM
AIR BEING PULLED FROM THE SE WILL KEEP PRECIP MOSTLY AS RAIN OVER
THE ERN CWA AND MOSTLY SNOW OVER THE WRN CWA. IN BETWEEN...VERTICAL
WET BULB TEMP PROFILES RIGHT AROUND 0C MAKES FOR A MORE DIFFICULT
PTYPE FORECAST...ESPECIALLY WITH UNCERTAINTY. COULD END UP WITH
ADVISORY LEVEL SNOWFALL...BUT UNCERTAINTY REMAINS TOO HIGH TO GET
SPECIFIC WITH SNOWFALL AMOUNTS. FOR THE REST OF TUE AND TUE
NIGHT...THE LOW OVER IA SHOULD WEAKEN AND TRAVERSE ACROSS THE
CWA...WITH ONLY MINOR PRECIP AMOUNTS DURING THIS PERIOD. TUE LOOKS
TO BE THE WARMEST DAY WITH HIGHS IN THE MID TO UPPER 30S.
THE ONLY MODEL CONTINUITY FOR THE FORMER...AND POSSIBLY COULD STILL
BE...CHRISTMAS EVE/DAY STORM IS THAT THERE HAS BEEN NO MODEL
CONTINUITY...AT LEAST OVER THE LAST FEW RUNS. MODELS DID HAVE AT
LEAST SOME DECENT CONTINUITY ABOUT 24 HOURS AGO...BUT AS IS FAIRLY
TYPICAL...ONCE THE FIRST SHORTWAVE MOVED CLOSE/INTO THE BETTER
OBSERVING NETWORK...MODELS DIVERGED FROM THEIR PREVIOUS SOLUTIONS
AND FROM OTHER MODEL SOLUTIONS. HAVE SEEN MODELS RECOVER FROM THE
SWING IN SOLUTIONS FOR SIMILAR STORMS IN THE PAST AND RETURN TO A
SOLUTION MUCH LIKE WAS SHOWED BEFORE THE MODELS SWING. THIS IS THE
CASE WITH THE NEWEST GFS (12Z/21) AS THE PREVIOUS RUN SHOWED THE
SYSTEM MUCH WEAKER AND FARTHER E...BUT THE NEW RUN SHOWS THE UPPER
TROUGH BEING SHARPER AND MORE NEGATIVELY TILTED...RESULTING IN A
CLOSED SFC LOW MOVING N TO LAKE SUPERIOR AT 987MB AT 00Z THU THEN
RAPIDLY MOVING TO ERN QUEBEC NEAR JAMES BAY AT 970MB AT 12Z THU.
WHILE THE GFS IS STILL AN OUTLIER SOLUTION...AND CONFIDENCE IS LOWER
WITH THE GFS DUE TO POOR ENSEMBLE CLUSTERING...THE SOLUTION SHOWN IS
STILL IN THE REALM OF POSSIBILITY. THE 00Z/21 ECMWF IS SIMILAR TO
THE 06Z GFS RUN IN SHOWING THE SYSTEM MUCH WEAKER AND FARTHER E.
EVEN IF THE FARTHEST W GFS VERIFIES...ONLY THE EXTREME ERN CWA WOULD
BE GRAZED BY THE GREATER SYNOPTIC PRECIP. WITH THE MORE BETTER
CONFIDENCE IN THE MORE ERN/WEAKER SOLUTION...PRECIP BEING ALL OR
MOSTLY SNOW BY WED IS FAVORED. STILL WILL SEE SOME SYNOPTIC
SNOW...BUT ONLY MINOR AMOUNTS...AS THE UPPER TROUGH SHIFTS ACROSS
THE AREA. WILL CONTINUE MONITORING CLOSELY...BUT CHANCES FOR A MAJOR
WINTER STORM APPEAR TO BE DWINDLING.
WITH 850MB TEMPS FALLING TO AROUND -8C BY THU AND W-WNW LOW LEVEL
WINDS...COULD SEE SOME LAKE ENHANCED/UPSLOPE SNOW OVER THE
W/KEWEENAW FROM WED NIGHT...WEAKENING THROUGH THE DAY THU AS THE
SYNOPTIC FORCING MOVES E. MODELS THEN BRING ANOTHER SHORTWAVE JUST
SW OF THE CWA ON FRI AHEAD OF AN UPPER TROUGH. OF COURSE...LOTS OF
UNCERTAINTY WITH THE SHORTWAVE...BUT COULD SEE SNOW FRI AS A RESULT.
LAKE EFFECT SNOW AND MUCH COLDER TEMPS ARE THE FOCUS WITH THE UPPER
TROUGH MOVING IN AS 850MB TEMPS FALL TO -20C TO -25C BY SAT MORNING
AND REMAIN OVER THE AREA INTO SUN. IF THIS OCCURS...WILL SEE A GOOD
LES EVEN IN WNW-NW WIND SNOWBELTS LATE FRI INTO AT LEAST SUN.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1236 AM EST MON DEC 22 2014
LIGHT/MODERATE SNOW CONTINUES ACROSS THE AREA UNDER A SOUTH FLOW OF
MOIST LLVL AIR WITH CONDITIONS RANGING FROM LIFR/VLIFR AT KCMX TO
MVFR AT KIWD. EXPECT IMPROVING CONDITIONS AT KCMX AND KSAW TO HIGH
END IFR LATE TONIGHT AND THEN TO MVFR LATE MON MORNING AS DRIER AIR
MOVES IN FM THE SOUTH. CONDITIONS WILL REMAIN MVFR THROUGH THE PD AT
KIWD AS DOWNSLOPE SOUTH WINDS SHOULD LIMIT LOWER CIGS AND VSBY
RESTRICTIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 425 AM EST MON DEC 22 2014
SSE WINDS UP TO 25-30 KTS OVER MAINLY THE E HALF OF LK SUPERIOR WILL
PERSIST THRU TODAY BUT THEN BACK TO THE E TONIGHT AND THEN THE NE ON
TUE AS A LO PRES SYSTEM MOVES NE FROM THE CENTRAL PLAINS TO OVER
LAKE MICHIGAN BY LATE IN THE DAY ON TUE. SINCE THIS LO WILL SLOWLY
WEAKEN AS IT MOVES TO THE NE...THE NE WINDS WILL FALL UNDER 20 KTS
ON TUE NIGHT. SINCE THE LATEST GUIDANCE INDICATES THE NEXT DEEPER LO
WILL TRACK N FARTHER TO THE E ON WED...A WEAKER PRES GRADIENT/N WIND
UNDER 20 KTS WILL DOMINATE ON WED. YET ANOTHER LO PRES MAY MOVE NE
FROM THE CENTRAL PLAINS LATE IN THE WEEK. AT THIS TIME...WINDS UNDER
25 KTS ARE EXPECTED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...VOSS
MARINE...KC
AREA FORECAST DISCUSSION
NWS DULUTH MN
1157 PM CST SUN DEC 21 2014
.UPDATE...
ISSUED AT 1157 PM CST SUN DEC 21 2014
BRIEF UPDATE TO ACCOUNT FOR RADAR TRENDS LATEST GUIDANCE. HAVE DECREASED
SNOWFALL AMOUNTS A BIT TO ACCOUNT FOR THE RAIN/SNOW MIX MOVING UP
FROM THE SOUTH. 00Z NAM/HIRES ARW/HIRES NMM/DLH WRF ALL SUGGEST A
CHANGEOVER TO MOSTLY SNOW NORTH OF HIGHWAY 2 IN NORTHERN MINNESOTA
TOWARDS THE MORNING...WITH THE BEST TIMING FOR SNOW ACROSS THE
ARROWHEAD BETWEEN 10Z AND 16Z. ALONG AND WEST OF HIGHWAY 53
AMOUNTS WILL BE LIGHT AND PRECIP TYPE WILL BE A MIX OF LIGHT
SNOW...FREEZING DRIZZLE/DRIZZLE...AND RAIN DEPENDING ON THE
STRENGTH OF THE MID/LOW LEVEL FORCING AND SURFACE TEMPERATURES.
WINTER WEATHER ADVISORY FOR ARROWHEAD LOOKS TO BE IN GOOD SHAPE AS
CKC /GRAND MARAIS AIRPORT/ HAS BEEN REPORTING LESS THAN 1/4 MI
VISIBILITY WITH A TEMP OF 30. COOK COUNTY DISPATCH DID NOT REPORT
ANY ACCIDENTS/SLIDE OFFS AT LAST REPORT BUT THAT ROADS IN THE
HIGHER TERRAIN WERE SLICK.
UPDATE ISSUED AT 817 PM CST SUN DEC 21 2014
WE ISSUED A WINTER WEATHER ADVISORY FOR TONIGHT INTO MONDAY
MORNING FOR THE IRON RANGE AND ARROWHEAD FOR A COMBINATION OF
FREEZING DRIZZLE AND LIGHT SNOW. AN AREA OF FREEZING DRIZZLE WAS
LIFTING NORTH THROUGH THOSE AREAS AND TEMPERATURES ARE A BIT
COOLER. BUFR SOUNDINGS SHOW MOISTENING AROUND OR SHORTLY AFTER
MIDNIGHT WHICH SHOULD CAUSE THE FREEZING DRIZZLE MIX WITH OR
CHANGE OVER TO SNOW.
UPDATE ISSUED AT 556 PM CST SUN DEC 21 2014
WAA AND A SHORTWAVE HAVE PRODUCED WIDESPREAD SNOW OVER MUCH OF
NORTHWEST WISCONSIN TODAY INTO EARLY THIS EVENING WITH SEVERAL
REPORTS OF 2 TO 3 INCHES SO FAR. RADAR SHOWS THIS SNOW WAS SLOWLY
DIMINISHING FROM WEST TO EAST AND THE VSBY AT KHYR HAS RISEN FROM
A HALF MILE TO 4 MILES. SATELLITE IMAGERY AND FORECAST SOUNDINGS
SHOW DRIZZLE/FREEZING DRIZZLE WILL BE POSSIBLE FURTHER WEST AND WE
HAVE HAD SEVERAL REPORTS OF THAT AS WELL. WE WILL UPDATE GRIDS TO
ACCOUNT FOR THE LATEST TRENDS/PRECIP TYPES.
STRONGER ECHOES WERE ALSO OCCURRING OVER PORTIONS OF SOUTHERN
MINNESOTA. THE HRRR BRINGS THIS AREA NORTH THROUGH THE NIGHT IN
LINE WITH THE OPERATIONAL RUNS. PRECIP TYPE LATER TONIGHT WILL
CONTINUE TO BE A CHALLENGE AND WE WILL MENTION OF MIX OF
SNOW/DRIZZLE OR FREEZING DRIZZLE DEPENDING ON SURFACE TEMPS. BUFR
SOUNDINGS AT KDLH SHOW SNOW BECOMING MORE LIKELY AROUND MIDNIGHT
AS THE COLUMN MOISTENS...WITH KINL LOOKING MORE LIKE
DRIZZLE/FREEZING DRIZZLE THROUGH THE NIGHT AS THE MOISTENING TAKES
LONGER TO REACH THAT AREA. WE WILL ALSO SEE LOW LEVEL TEMPS WARM
LATE TONIGHT INTO MONDAY MORNING WHICH COULD AGAIN CAUSE A MIX TO
OCCUR.
FOG WILL CONTINUE OVERNIGHT WITH LOWEST VSBYS AROUND LAKE
SUPERIOR. WE MAY NEED A DENSE FOG ADVISORY FOR THE NORTH SHORE
DOWN INTO THE TWIN PORTS AREA...BUT WILL WAIT A BIT LONGER BEFORE
ISSUING ONE AS VSBYS HAVE AT LEAST FOR THE TIME BEING COME UP SOME.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY AFTERNOON)
ISSUED AT 329 PM CST SUN DEC 21 2014
MAIN CONCERNS IN THE SHORT TERM REMAIN FOCUSED AROUND THE
INCOMING...LONG DURATION WINTER STORM EXPECTED TO IMPACT THE
NORTHLAND EARLY THIS WEEK WITH A WINTRY MIX OF SNOW...RAIN...SLEET
AND FREEZING DRIZZLE POSSIBLE.
A WINTER STORMS WATCH REMAINS IN EFFECT FOR THE ARROWHEAD INCLUDING
LAKE AND COOK COUNTIES...BUT THE TIME HAS BEEN ADJUSTED TO START
MONDAY NIGHT AND END WEDNESDAY MORNING. THE MAIN CONCERNS WITHIN THE
WATCH AREA WILL BE THE POTENTIAL FOR HEAVY SNOW ACCUMULATIONS.
AN INITIAL LEAD S/W IS ROTATING NEWD THROUGH THE UPPER MIDWEST AND
WRN ONTARIO THIS AFTERNOON AND WILL MOVE SLOWLY EWD TONIGHT AS WEAK
RIDGING ALOFT AND AN ASSOCIATED DRY SLOT PUSH IN FROM THE SOUTH
BEHIND THE WAVE AND AHEAD OF THE MAIN LOW PRESSURE SYSTEM SWINGING
THROUGH THE MIDWEST MON NIGHT THROUGH WEDNESDAY.
WILL SEE SNOW SHOWERS PERSIST THROUGH THIS EVENING WITH LIGHT
ACCUMULATIONS LIKELY. THE HEAVIEST SNOW AMTS TONIGHT WILL BE ACROSS
THE ARROWHEAD AND INTO PORTIONS OF NW WI WHERE AN ADDITIONAL 1 TO 2
INCHES IS POSSIBLE. AS THE UPPER WAVE SLIDES NEWD AND THE RIDGE
BUILDS IN...THE DRY AIR ALOFT WILL ALLOW THE COLUMN TO LOSE ICE
CRYSTALS AND CHANGE THE PRECIP FROM LIGHT SNOW OVER TO A LIGHT
FREEZING DRIZZLE. TEMPERATURES WILL ALSO WARM GRADUALLY THROUGH THE
NIGHT FROM THE LOWER 30S EARLY THIS EVENING TO THE MID 30S BY MON
MORNING. TEMPERATURES ALOFT WILL WARM AS WELL WITH A NOSE OF 0 TO +1
DEG C AIR LIFTS NWD INTO THE AREA AND ALLOWS THE PRECIP TO CHANGE
OVER TO A MIX OF RAIN/SNOW AND/OR SLEET DURING THE DAY MONDAY. WILL
LIKELY SEE WIDESPREAD SNOWFALL AMTS ON MONDAY RANGE FROM A HALF TO
ONE INCH...WITH CLOSER TO 2 TO 3 INCHES POSSIBLE OVER THE ARROWHEAD.
BETTER CHANCES FOR ACCUMULATING SNOW EXIST MON NIGHT THROUGH TUE
NIGHT.
PATCHY FOG WILL ALSO PERSIST TONIGHT AND INTO EARLY IN THE WEEK.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 329 PM CST SUN DEC 21 2014
EXTENDED RANGE FOCUS ON LONG WAVE TROUGH WITH CLOSED H50 THAT TRACKS
THROUGH THE CENTRAL PLAINS AND LIFTS INTO THE GREAT LAKES REGION
DURING THE TUESDAY/WEDNESDAY PERIODS.
ALTHOUGH MODELS ARE COMING INTO BETTER ALIGNMENT...THERE CONTINUES
TO BE RUN TO RUN DIFFERENCES IN TRACK OF THE LOW...WHICH WILL BE THE
DETERMINING FACTOR FOR PLACEMENT OF THE BEST FORCING AND HIGHEST
SNOWFALL AMOUNTS. AT THIS TIME...THE SFC LOW IS FCST TO TRACK OVER
WISCONSIN MONDAY NIGHT/TUESDAY...WHICH WILL PRODUCE GUST NORTHEAST
WINDS OVER LAKE SUPERIOR WHILE ROTATING A BAND OF SNOW LOCATED IN A
DEFORMATION ZONE ON THE ON THE NW FLANK OF THE LOW ACROSS MUCH OF
THE NORTHLAND. LATEST GUIDANCE IS SUGGESTING THAT A CORRIDOR OF QPF
AMOUNTS IN EXCESS OF A HALF INCH WILL BE FOUND DURING THIS TIME DUE
TO THE ABUNDANCE OF MOISTURE AND HIGH PWAT VALUES. ALTHOUGH DETAILS
HAVE YET TO BE REFINED AND SFC TEMPS MAY WARRANT SOME INITIAL MIXING
OF SNOW/RAIN/DRIZZLE...SNOWFALL TOTALS FOR THE MONDAY NIGHT THROUGH
WEDNESDAY MORNING TIME FRAME OF GENERALLY 4 TO 8 INCHES ARE EXPECTED
OVER THE NORTHLAND. THE GREATEST UNCERTAINTY IS IN THE WESTERN HALF
ZONES /NORTH CENTRAL MN/ WHERE A WEDGE OF DRY AIR WILL WRAP AROUND
THE LOW AND LIMIT SNOWFALL TOTALS.
DUE TO THE LONG DURATION OF THE SNOW...ANTICIPATING THAT A WINTER
WEATHER ADVISORY WILL BE NEEDED FOR MUCH OF THE FORECAST AREA DURING
THE MONDAY NIGHT INTO EARLY WEDNESDAY PERIODS.
LONG RANGE MODELS SHOW THE ACTIVE PATTERN THROUGH THE REMAINDER OF
THE EXTENDED FCST...WITH A PERSISTENT CYCLONIC FLOW AND EMBEDDED
SHORT WAVES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1132 PM CST SUN DEC 21 2014
IFR/LIFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD AS PLENTY
OF MOISTURE COVERED THE REGION. AN AREA OF LOW PRESSURE WILL
CONTINUE TO IMPACT THE NORTHLAND THROUGH MONDAY NIGHT WITH PERIODS
OF PRECIPITATION. PRECIPITATION TYPE WILL CONTINUE TO BE A
CHALLENGE. MAINLY DRIZZLE OR FREEZING DRIZZLE WILL OCCUR WHEN THE
PRECIP IS AT ITS LIGHTEST...WITH SLEET OR SNOW OCCURRING WHEN
STRONGER ECHOES MOVE THROUGH. ONE AREA OF STRONGER ECHOES/LIFT WAS
MOVING NORTH UP THE SAINT CROIX RIVER VALLEY INTO NORTHERN
WISCONSIN. BUFR SOUNDINGS CONTINUE TO SHOW ENOUGH SATURATION
OCCURRING AT KHYR/KDLH FOR THE PRECIP TO MIX WITH OR CHANGE OVER
TO SNOW FOR A TIME TONIGHT.
THE LATEST GUIDANCE SUGGESTS THE PRECIP WILL DIMINISH FROM EAST TO
WEST MONDAY AFTERNOON INTO MONDAY EVENING. HOWEVER...WE EXPECT FOG AND
AREAS OF DRIZZLE TO PERSIST.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 33 36 33 36 / 100 90 80 80
INL 31 36 32 33 / 90 80 70 70
BRD 32 35 31 34 / 90 90 80 80
HYR 34 36 33 35 / 100 80 80 80
ASX 33 38 33 36 / 100 70 80 80
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL 10 AM CST MONDAY FOR MNZ011-012-
019>021.
WINTER STORM WATCH FROM LATE MONDAY NIGHT THROUGH LATE TUESDAY
NIGHT FOR MNZ012-020-021.
WI...NONE.
LS...NONE.
&&
$$
UPDATE...JJM/MELDE
SHORT TERM...BJT
LONG TERM...GRANING
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS DULUTH MN
1132 PM CST SUN DEC 21 2014
.UPDATE...
ISSUED AT 817 PM CST SUN DEC 21 2014
WE ISSUED A WINTER WEATHER ADVISORY FOR TONIGHT INTO MONDAY
MORNING FOR THE IRON RANGE AND ARROWHEAD FOR A COMBINATION OF
FREEZING DRIZZLE AND LIGHT SNOW. AN AREA OF FREEZING DRIZZLE WAS
LIFTING NORTH THROUGH THOSE AREAS AND TEMPERATURES ARE A BIT
COOLER. BUFR SOUNDINGS SHOW MOISTENING AROUND OR SHORTLY AFTER
MIDNIGHT WHICH SHOULD CAUSE THE FREEZING DRIZZLE MIX WITH OR
CHANGE OVER TO SNOW.
UPDATE ISSUED AT 556 PM CST SUN DEC 21 2014
WAA AND A SHORTWAVE HAVE PRODUCED WIDESPREAD SNOW OVER MUCH OF
NORTHWEST WISCONSIN TODAY INTO EARLY THIS EVENING WITH SEVERAL
REPORTS OF 2 TO 3 INCHES SO FAR. RADAR SHOWS THIS SNOW WAS SLOWLY
DIMINISHING FROM WEST TO EAST AND THE VSBY AT KHYR HAS RISEN FROM
A HALF MILE TO 4 MILES. SATELLITE IMAGERY AND FORECAST SOUNDINGS
SHOW DRIZZLE/FREEZING DRIZZLE WILL BE POSSIBLE FURTHER WEST AND WE
HAVE HAD SEVERAL REPORTS OF THAT AS WELL. WE WILL UPDATE GRIDS TO
ACCOUNT FOR THE LATEST TRENDS/PRECIP TYPES.
STRONGER ECHOES WERE ALSO OCCURRING OVER PORTIONS OF SOUTHERN
MINNESOTA. THE HRRR BRINGS THIS AREA NORTH THROUGH THE NIGHT IN
LINE WITH THE OPERATIONAL RUNS. PRECIP TYPE LATER TONIGHT WILL
CONTINUE TO BE A CHALLENGE AND WE WILL MENTION OF MIX OF
SNOW/DRIZZLE OR FREEZING DRIZZLE DEPENDING ON SURFACE TEMPS. BUFR
SOUNDINGS AT KDLH SHOW SNOW BECOMING MORE LIKELY AROUND MIDNIGHT
AS THE COLUMN MOISTENS...WITH KINL LOOKING MORE LIKE
DRIZZLE/FREEZING DRIZZLE THROUGH THE NIGHT AS THE MOISTENING TAKES
LONGER TO REACH THAT AREA. WE WILL ALSO SEE LOW LEVEL TEMPS WARM
LATE TONIGHT INTO MONDAY MORNING WHICH COULD AGAIN CAUSE A MIX TO
OCCUR.
FOG WILL CONTINUE OVERNIGHT WITH LOWEST VSBYS AROUND LAKE
SUPERIOR. WE MAY NEED A DENSE FOG ADVISORY FOR THE NORTH SHORE
DOWN INTO THE TWIN PORTS AREA...BUT WILL WAIT A BIT LONGER BEFORE
ISSUING ONE AS VSBYS HAVE AT LEAST FOR THE TIME BEING COME UP SOME.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY AFTERNOON)
ISSUED AT 329 PM CST SUN DEC 21 2014
MAIN CONCERNS IN THE SHORT TERM REMAIN FOCUSED AROUND THE
INCOMING...LONG DURATION WINTER STORM EXPECTED TO IMPACT THE
NORTHLAND EARLY THIS WEEK WITH A WINTRY MIX OF SNOW...RAIN...SLEET
AND FREEZING DRIZZLE POSSIBLE.
A WINTER STORMS WATCH REMAINS IN EFFECT FOR THE ARROWHEAD INCLUDING
LAKE AND COOK COUNTIES...BUT THE TIME HAS BEEN ADJUSTED TO START
MONDAY NIGHT AND END WEDNESDAY MORNING. THE MAIN CONCERNS WITHIN THE
WATCH AREA WILL BE THE POTENTIAL FOR HEAVY SNOW ACCUMULATIONS.
AN INITIAL LEAD S/W IS ROTATING NEWD THROUGH THE UPPER MIDWEST AND
WRN ONTARIO THIS AFTERNOON AND WILL MOVE SLOWLY EWD TONIGHT AS WEAK
RIDGING ALOFT AND AN ASSOCIATED DRY SLOT PUSH IN FROM THE SOUTH
BEHIND THE WAVE AND AHEAD OF THE MAIN LOW PRESSURE SYSTEM SWINGING
THROUGH THE MIDWEST MON NIGHT THROUGH WEDNESDAY.
WILL SEE SNOW SHOWERS PERSIST THROUGH THIS EVENING WITH LIGHT
ACCUMULATIONS LIKELY. THE HEAVIEST SNOW AMTS TONIGHT WILL BE ACROSS
THE ARROWHEAD AND INTO PORTIONS OF NW WI WHERE AN ADDITIONAL 1 TO 2
INCHES IS POSSIBLE. AS THE UPPER WAVE SLIDES NEWD AND THE RIDGE
BUILDS IN...THE DRY AIR ALOFT WILL ALLOW THE COLUMN TO LOSE ICE
CRYSTALS AND CHANGE THE PRECIP FROM LIGHT SNOW OVER TO A LIGHT
FREEZING DRIZZLE. TEMPERATURES WILL ALSO WARM GRADUALLY THROUGH THE
NIGHT FROM THE LOWER 30S EARLY THIS EVENING TO THE MID 30S BY MON
MORNING. TEMPERATURES ALOFT WILL WARM AS WELL WITH A NOSE OF 0 TO +1
DEG C AIR LIFTS NWD INTO THE AREA AND ALLOWS THE PRECIP TO CHANGE
OVER TO A MIX OF RAIN/SNOW AND/OR SLEET DURING THE DAY MONDAY. WILL
LIKELY SEE WIDESPREAD SNOWFALL AMTS ON MONDAY RANGE FROM A HALF TO
ONE INCH...WITH CLOSER TO 2 TO 3 INCHES POSSIBLE OVER THE ARROWHEAD.
BETTER CHANCES FOR ACCUMULATING SNOW EXIST MON NIGHT THROUGH TUE
NIGHT.
PATCHY FOG WILL ALSO PERSIST TONIGHT AND INTO EARLY IN THE WEEK.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 329 PM CST SUN DEC 21 2014
EXTENDED RANGE FOCUS ON LONG WAVE TROUGH WITH CLOSED H50 THAT TRACKS
THROUGH THE CENTRAL PLAINS AND LIFTS INTO THE GREAT LAKES REGION
DURING THE TUESDAY/WEDNESDAY PERIODS.
ALTHOUGH MODELS ARE COMING INTO BETTER ALIGNMENT...THERE CONTINUES
TO BE RUN TO RUN DIFFERENCES IN TRACK OF THE LOW...WHICH WILL BE THE
DETERMINING FACTOR FOR PLACEMENT OF THE BEST FORCING AND HIGHEST
SNOWFALL AMOUNTS. AT THIS TIME...THE SFC LOW IS FCST TO TRACK OVER
WISCONSIN MONDAY NIGHT/TUESDAY...WHICH WILL PRODUCE GUST NORTHEAST
WINDS OVER LAKE SUPERIOR WHILE ROTATING A BAND OF SNOW LOCATED IN A
DEFORMATION ZONE ON THE ON THE NW FLANK OF THE LOW ACROSS MUCH OF
THE NORTHLAND. LATEST GUIDANCE IS SUGGESTING THAT A CORRIDOR OF QPF
AMOUNTS IN EXCESS OF A HALF INCH WILL BE FOUND DURING THIS TIME DUE
TO THE ABUNDANCE OF MOISTURE AND HIGH PWAT VALUES. ALTHOUGH DETAILS
HAVE YET TO BE REFINED AND SFC TEMPS MAY WARRANT SOME INITIAL MIXING
OF SNOW/RAIN/DRIZZLE...SNOWFALL TOTALS FOR THE MONDAY NIGHT THROUGH
WEDNESDAY MORNING TIME FRAME OF GENERALLY 4 TO 8 INCHES ARE EXPECTED
OVER THE NORTHLAND. THE GREATEST UNCERTAINTY IS IN THE WESTERN HALF
ZONES /NORTH CENTRAL MN/ WHERE A WEDGE OF DRY AIR WILL WRAP AROUND
THE LOW AND LIMIT SNOWFALL TOTALS.
DUE TO THE LONG DURATION OF THE SNOW...ANTICIPATING THAT A WINTER
WEATHER ADVISORY WILL BE NEEDED FOR MUCH OF THE FORECAST AREA DURING
THE MONDAY NIGHT INTO EARLY WEDNESDAY PERIODS.
LONG RANGE MODELS SHOW THE ACTIVE PATTERN THROUGH THE REMAINDER OF
THE EXTENDED FCST...WITH A PERSISTENT CYCLONIC FLOW AND EMBEDDED
SHORT WAVES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1132 PM CST SUN DEC 21 2014
IFR/LIFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD AS PLENTY
OF MOISTURE COVERED THE REGION. AN AREA OF LOW PRESSURE WILL
CONTINUE TO IMPACT THE NORTHLAND THROUGH MONDAY NIGHT WITH PERIODS
OF PRECIPITATION. PRECIPITATION TYPE WILL CONTINUE TO BE A
CHALLENGE. MAINLY DRIZZLE OR FREEZING DRIZZLE WILL OCCUR WHEN THE
PRECIP IS AT ITS LIGHTEST...WITH SLEET OR SNOW OCCURRING WHEN
STRONGER ECHOES MOVE THROUGH. ONE AREA OF STRONGER ECHOES/LIFT WAS
MOVING NORTH UP THE SAINT CROIX RIVER VALLEY INTO NORTHERN
WISCONSIN. BUFR SOUNDINGS CONTINUE TO SHOW ENOUGH SATURATION
OCCURRING AT KHYR/KDLH FOR THE PRECIP TO MIX WITH OR CHANGE OVER
TO SNOW FOR A TIME TONIGHT.
THE LATEST GUIDANCE SUGGESTS THE PRECIP WILL DIMINISH FROM EAST TO
WEST MONDAY AFTERNOON INTO MONDAY EVENING. HOWEVER...WE EXPECT FOG AND
AREAS OF DRIZZLE TO PERSIST.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 33 35 33 36 / 70 90 80 80
INL 31 35 32 33 / 50 80 70 70
BRD 32 35 31 34 / 70 90 80 80
HYR 34 35 33 35 / 70 80 80 80
ASX 33 37 33 36 / 70 70 80 80
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL 10 AM CST MONDAY FOR MNZ011-012-
019>021.
WINTER STORM WATCH FROM LATE MONDAY NIGHT THROUGH LATE TUESDAY
NIGHT FOR MNZ012-020-021.
WI...NONE.
LS...NONE.
&&
$$
UPDATE...MELDE
SHORT TERM...BJT
LONG TERM...GRANING
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1152 PM CST SUN DEC 21 2014
.UPDATE...
ISSUED AT 524 PM CST SUN DEC 21 2014
A LIGHT MIST HAS FORMED ACROSS PORTIONS OF THE FORECAST AREA AND
BASED ON RADAR TRENDS IS EXPANDING IN COVERAGE AREA. IN
ADDITION...FORECAST SOUNDINGS INDICATE THAT THE SATURATED STRATUS
LAYER IS NOW THICKER THAN 1 KM...WHICH IS A SUFFICIENT DEPTH FOR
DRIZZLE FORMATION. THEREFORE...HAVE INTRODUCED DRIZZLE TO THE
FORECAST FOR THE EVENING AND EARLY MORNING HOURS.
SATELLITE IMAGERY INDICATES OVERCAST CONDITIONS ACROSS OUR ENTIRE
FORECAST AREA AND LATEST NAM AND RUC RH FIELDS SHOW LITTLE HOPE
FOR ANY BREAKS IN THE CLOUDS THROUGH THE OVERNIGHT HOURS ACROSS
MOST OF OUR FORECAST AREA. THEREFORE...HAVE INCREASED CLOUD COVER
FOR TONIGHT TO 100 PERCENT CLOUD COVER FOR MOST AREAS EXCEPT FOR
FAR SOUTHWESTERN ZONES WHERE THERE COULD BE A FEW BREAKS IN THE
CLOUDS. BUT EVEN ACROSS SOUTHWESTERN ZONES IT SHOULD STILL BE
MOSTLY CLOUDY TONIGHT.
THE COMBINATION OF CLOUDS...DRIZZLE...AND EVEN LIGHT RAIN LATER
TONIGHT WILL KEEP SURFACE TEMPERATURES NEARLY STEADY THROUGH THE
OVERNIGHT HOURS...WHICH IS SUPPORTED BY MOST FORECAST MODELS.
THEREFORE...INCREASED LOWS FOR TONIGHT BY A FEW DEGREES KEEPING
ALL AREAS ABOVE FREEZING TONIGHT FOR LOWS. THE NEAR SURFACE LAYER
(SFC-875MB) SHOULD BE SUFFICIENTLY WARM BASED ON MODEL FORECAST
SOUNDINGS TO KEEP ALL PRECIPITATION IN THE LIQUID FORM THROUGH THE
OVERNIGHT HOURS.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 349 PM CST SUN DEC 21 2014
SATELLITE AND OBSERVATIONS CONTINUE TO SHOW A VERY PERSISTENT AREA
OF LOW CLOUDS AND FOG OVER PORTIONS OF THE FORECAST AREA. MID LEVEL
CLOUDS FROM THE WEST ARE MOVING INTO THE AREA AND MAKING IT HARDER
TO SEE THE STRATUS...BUT RECENT SATELLITE TRENDS HAS BEEN FOR THE
NORTH/NORTHWEST PROGRESSION OF THE STRATUS HAS SLOWED OR EVEN
STOPPED. DURING THE DAYTIME THE FOG HAS REDUCED VISIBILITY MORE THAN
EARLY THIS MORNING. EVEN WITH GOOD SOUTH WINDS THE FOG HAS SPREAD
ACROSS THE FORECAST AREA. THE SOUTH WINDS HAVE BROUGHT A CONTINUE
STREAM OF MORE MOIST AIR INTO THE REGION WHICH COULD ACCOUNT FOR
SOME OF THE INCREASE IN CLOUDS AND FOG.
A WEAK UPPER LEVEL WAVE MOVED THROUGH THE FORECAST AREA TODAY. THIS
IS HELPING TO BRING IN THE MID LEVEL CLOUDS. AT THE SURFACE THERE IS
A DEVELOPING LOW AND COLD FRONT ON THE HIGH PLAINS. THIS COLD FRONT
IS EXPECTED TO MOVE THROUGH THE FORECAST AREA TONIGHT AS A STRONGER
UPPER LEVEL WAVE APPROACHES THE AREA. PRECIPITATION IS EXPECTED TO
DEVELOP TO THE WEST LATE THIS AFTERNOON AND SPREAD INTO THE AREA
THIS EVENING AND TONIGHT. THE BEST CHANCES FOR PRECIPITATION WILL BE
IN THE NORTH AND IN THE EAST. THE PRECIPITATION SHOULD BE MAINLY OUT
OF THE FORECAST AREA BY MORNING. LOOKING AT FORECAST SOUNDINGS THE
PRECIPITATION SHOULD BE RAIN DURING THE NIGHT TONIGHT. TEMPERATURES
SHOULD REMAIN WARM ENOUGH THAT IT WILL BE LIQUID. THE NORTHWEST HAVE
LOW TEMPERATURES THAT ARE AROUND FREEZING BY MORNING...BUT
PRECIPITATION SHOULD BE OUT OF THERE BEFORE IT ACTUALLY DROPS BELOW
FREEZING.
ON MONDAY THE PRECIPITATION SHOULD BE WRAP AROUND FROM THE UPPER LOW
IN THE DAKOTAS. BY THEN THE TEMPERATURES ALOFT START TO COOL OFF AND
SO THERE WILL BE SOME RAIN AND SNOW MIXED DURING THE MORNING IN THE
NORTH. BY AFTERNOON IT SPREADS A LITTLE FURTHER SOUTH. BY THIS TIME
THE SURFACE TEMPERATURES WARM A LITTLE AS THE TEMPERATURES ALOFT
COOL AND ONCE AGAIN EXPECT A MIX OF RAIN AND SNOW. BY LATE IN THE
AFTERNOON TEMPERATURES COULD BE FALLING IN THE FAR NORTH.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 349 PM CST SUN DEC 21 2014
WE START OFF THE LONG TERM MONDAY NIGHT ON THE BACK SIDE OF A MID-
UPPER CLOSED LOW...ASSOCIATED WITH A DEEPENING LONGWAVE TROUGH AS IT
MOVES TOWARD THE MISSISSIPPI VALLEY. FROM MONDAY NIGHT INTO
TUESDAY/TUESDAY EVENING...WE WILL BE IN A REGION OF LIGHT WRAP
AROUND PRECIPITATION...KEEPING RATHER GLOOMY CONDITIONS AROUND
LONGER. THE TRICKY PART IS FIGURING OUT WHAT GOES ON TUESDAY. MOST
NUMERICAL MODELS ARE PLACING AT LEAST SOME QPF OVER THE CWA...AND
THE NAM/SREF ARE HITTING OUR KANSAS COUNTIES HARDER. THE NAM IS
DISPLAYING .20 INCHES OF QPF AND HAS BEEN CONSISTENT WITH THIS IN
THE PAST COUPLE OF RUNS. THE PROBLEM IS THAT I DO NOT SEE ENOUGH
EVIDENCE TO SUPPORT THE HIGHER CHANCES OF PRECIPITATION ADVERTISED
BY THE SREF ENSEMBLES AND THE NAM QPF. ALL NUMERICAL MODELS SEEM TO
BREAK OFF A SMALL PIECE OF ENERGY THAT WRAPS AROUND THE CLOSED LOW
THAT SHOULD BE LOCATED JUST NORTHEAST OF THE CWA. THIS IS QUITE A
SMALL FEATURE AND IT IS DIFFICULT TO JUDGE WHERE AND IF THIS ENDS UP
ANYWHERE OVER OUR CWA. THERE IS A FAIR AMOUNT OF DOWNGLIDE AND THERE
DOES NOT APPEAR TO BE MUCH SYNOPTIC SCALE LIFT FOR SUPPORT. THERE IS
SOME MID-LEVEL FRONTOGENETIC FORCING FROM THE NAM. THIS WILL BE AN
AREA TO KEEP AN EYE ON. OUR STORM TOTAL SNOW GRID IS GENERALLY IN
THE 1 TO 2 INCH RANGE FOR MONDAY NIGHT/TUESDAY. I HAVE OPTED TO GO A
BIT HIGHER WITH POPS FROM MY NEIGHBORS AND GO WITH 40 POPS...AS I
STILL AM UNCOMFORTABLE WITH WIDE AGREEMENT AMONG MOST NUMERICAL
MODELS THAT WE WILL MEASURE.
WE WILL GET A REPRIEVE FROM PRECIPITATION CHANCES WEDNESDAY...WITH
UPPER LEVEL RIDGING OCCURRING...BUT THIS WILL BE SHORT-LIVED AS
SYNOPTIC FLOW IS PROGRESSIVE. THE TROUGH HITTING THE PACIFIC
NORTHWEST WEDNESDAY EVENING COULD GIVE US A SHOT AT PRECIPITATION AS
EARLY AS THURSDAY AFTERNOON...ESPECIALLY NORTHWEST AS THE TROUGH BY
00Z FRIDAY WILL IS FORECAST TO BE POSITIVELY TILTED FROM THE
NORTHERN GREAT PLAINS TO THE CENTRAL/SOUTHERN ROCKY MOUNTAINS. THIS
QUICK-MOVING WAVE CAN GIVE US A SHOT AT SOME SNOW...BUT AMOUNTS DO
NOT LOOK OVERWHELMING AS THE TROUGH AXIS MAKES ITS WAY EAST OF THE
CWA BY LATE THURSDAY NIGHT...NOT HANGING AROUND LONG ENOUGH FOR
LARGER AMOUNTS. WIND WILL KICK UP BEHIND THE ASSOCIATED COLD FRONT
THURSDAY NIGHT...PROBABLY REDUCING VISIBILITY CHRISTMAS NIGHT FROM
THE BLOWING SNOW. THE WIND WILL CONTINUE TO BE BRISK ON
FRIDAY...CREATING AN UNCOMFORTABLE DAY AFTER CHRISTMAS...WITH COOLER
HIGHS BEHIND THE COLD FRONT NEAR 30 TO THE MID 30S. STILL LOOKS
TROUGHY HEADING INTO THE WEEKEND...SO THE DRY FORECAST IS NOT THE
MOST CONFIDENT. TEMPERATURES WILL BE SEASONABLY COOL.
NUMERICAL MODELS ARE SYNOPTICALLY SIMILAR FOR THE LONG TERM...SO
CONFIDENCE IS FAIRLY HIGH FOR TEMPERATURES AND FOR THE MOST
PART...PRECIPITATION...ALTHOUGH THERE ARE SMALLER SCALE DIFFERENCES
THAT NEED TO BE HAMMERED OUT AS WE APPROACH THEM.
&&
.AVIATION...(FOR THE 06Z KGRI/KEAR TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1138 PM CST SUN DEC 21 2014
AN UPPER LEVEL DISTURBANCE CROSSING THE REGION WILL BE THE DRIVING
FORCE FOR THE WEATHER OVER THIS TAF PERIOD. NOT A WHOLE LOT OF
PRECIP IN THE AREA AT THE MOMENT...BUT THERE IS ANOTHER SMALL
BATCH WHICH WILL MOVE IN FROM THE NW WITH TIME. DECIDED TO KEEP
PRECIP MENTION AT A TEMPO GROUP...AS THE RAP/HRRR MODELS SUGGEST
THAT IT MAY NOT HOLD TOGETHER. WILL SEE HOW THINGS TREND OVER THE
NEXT FEW HOURS. OTHERWISE...EXPECTING IFR CEILINGS TO STICK
AROUND...VISBYS ARE VFR BUT WOULDNT BE SURPRISED TO SEE THEM AT
LEAST BRIEFLY DROP TO MVFR. MAY SEE SOME IMPROVEMENT DURING THE
DAYTIME HOURS WITH A COLD FRONT MOVING THROUGH THE REGION...AND
NWRLY WINDS BEHIND THE FRONT WILL INCREASE TO NEAR 20 MPH WITH
HIGHER GUSTS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...WESELY
SHORT TERM...JCB
LONG TERM...HEINLEIN
AVIATION...ADP
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1246 AM CST MON DEC 22 2014
.UPDATE...
ISSUED AT 1246 AM CST MON DEC 22 2014
SURFACE LOW WAS OVER WILLISTON/WATFORD CITY AREA WITH A TROUGH
EXTENDING SOUTHEAST INTO CENTRAL SOUTH DAKOTA. SOUTHEAST WINDS AHEAD
OF THE TROUGH HAD PULLED STRATUS AND FOG WESTWARD DURING THE
EVENING. WEST OF THE TROUGH WINDS HAD BECOME NORTHWESTERLY AND
EXPECT COLD AIR TO BEGIN FILTERING IN GRADUALLY BEHIND THIS SYSTEM.
TEMPERATURES WERE IN THE 20S OVER SOUTHERN SASKATCHEWAN...WITH MID
30S IN NORTHEASTERN MONTANA. TEMPERATURES STILL IN THE MID AND UPPER
30S OVER SOUTHWESTERN NORTH DAKOTA.
PRECIPITATION COVERAGE IS SPARSE AT THIS TIME...BUT REPORTS EARLIER
THIS EVENING INDICATED PRECIPITATION TYPE AS RAIN. GLASGOW MONTANA
BEGAN REPORTING LIGHT SNOW AT 05Z OR 11 PM CST. THUS THE ONSET OF
LIGHT SNOW IS LATER THAN PREVIOUSLY FORECAST. HAVE ADJUSTED THIS
TIMING...SUCH THAT BY 3-4AM CST OR 2-3 AM MST LIGHT SNOW COULD BE
FALLING IN THE FAR SOUTHWEST...AROUND BEACH OR BOWMAN/HETTINGER.
REGARDING THE SPARSE COVERAGE...LATEST DOPPLER RADAR LOOPS INDICATED
THAT LIGHT RADAR RETURNS WERE BEGINNING TO INCREASE OVER
NORTHEASTERN MONTANA...ALONG THE MISSOURI RIVER IN NORTH
DAKOTA...AND LIGHT RETURNS SEEN ON THE BOWMAN RADAR FROM BAKER MT TO
HETTINGER. THINKING THAT WITH TIME THIS MORNING THERE WILL BE MORE
INSTABILITY ACROSS THIS REGION AS THE ENERGY FROM THE UPPER LEVEL
SHORTWAVE CONTINUES MOVING INTO WESTERN NORTH DAKOTA.
THUS PRECIPITATION THAT FALLS SHOULD BE RAIN SOUTHWEST...CHANGING TO
LIGHT SNOW. NORTHWEST SHOULD SEE A MIX OF LIGHT SNOW OR FREEZING
RAIN BEFORE CHANGING QUICKLY OVER TO SNOW. FARTHER EAST IN CENTRAL
NORTH DAKOTA AREAS OF FOG WILL PERSIST...THEN THE FREEZING RAIN
THREAT WILL LINGER UNTIL AROUND 4-5 AM CST WHEN PRECIPITATION SHOULD
BE ALL SNOW.
UPDATE ISSUED AT 928 PM CST SUN DEC 21 2014
WIDESPREAD FOG WITH VISIBILITIES BETWEEN ONE HALF AND 2 MILES COVER
CENTRAL AND EASTERN NORTH DAKOTA. ONLY MINOT AFB SHOWING SOME
FREEZING DRIZZLE AT 9 PM CST. WILL DELAY THE FREEZING DRIZZLE
SOUTH CENTRAL AND EAST CENTRAL FOR THE EVENING INTO THE OVERNIGHT
HOURS BUT EVENTUALLY SOME SHOULD SHOW UP. WILL KEEP MENTION OF
FREEZING DRIZZLE NORTH CENTRAL WHERE AT LEAST MINOT AFB IS SHOWING
SOME. STILL RAINING SOUTHWEST WITH TEMPERATURES ACROSS THE AREA
STILL IN THE MID/UPPER 30S. STILL WAITING FOR COOLER AIR TO ARRIVE
FOR THE CHANGEOVER TO SNOW WEST WHICH SHOULD HAPPEN AFTER
MIDNIGHT.
UPDATE ISSUED AT 637 PM CST SUN DEC 21 2014
COMPLEX WINTER WEATHER PATTERN BEGINNING AS RAIN ACROSS THE WEST
THIS EVENING.LOW STRATUS AND FOG CONTINUE ACROSS THE CENTRAL AND
EAST. THE POTENTIAL FOR FREEZING DRIZZLE REMAINS THERE. BASED ON
CURRENT TRENDS THE FORECAST IS OK SO FAR. WINTER WEATHER ADVISORY
BEGINS AT 06Z/11PM MST SOUTHWEST THIS EVENING.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 312 PM CST SUN DEC 21 2014
FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE
PLENTIFUL...RAIN CHANGING TO SNOW WEST THIS EVENING WITH
ACCUMULATIONS AND INCREASING WIND INTO MONDAY...AREAS OF FOG AND
PATCHY FREEZING DRIZZLE EAST...AND MORE ACCUMULATING SNOW
SOUTHEAST DEVELOPING MONDAY MORNING AND AFTERNOON.
CURRENTLY...INCOMING STORM SYSTEM ON THE NOSE OF A POWERFUL 150KT
+ UPPER LEVEL JET STREAK NOW OVER THE NORTHERN ROCKIES. ASSOCIATED
SURFACE LOW DEVELOPING AND MOVING SOUTHEAST FROM SOUTHERN ALBERTA
INTO EASTERN MONTANA. CURRENT PRECIPITATION ORIENTATED ALONG THE
SURFACE LOW`S WARM FRONT...FROM NORTH OF GLASGOW MT SOUTHEAST
INTO FAR SOUTHWESTERN NORTH DAKOTA. AREA OF LOW STRATUS AND FOG
ACROSS THE JAMES RIVER VALLEY CONTINUES TO SPREAD SLOWLY NORTH AND
WEST THANKS TO A MOIST SOUTHEASTERLY LOW LEVEL FLOW AHEAD OF THE
SFC LOW.
COMPLEX FORECAST OVER THE NEXT 24-36 HOURS. AS THE
HRRR...NAM...AND RAP ALL INDICATE...STRATUS AND FOG NOW OVER THE
JAMES VALLEY WILL CONTINUE TO EXPAND WEST AND NORTH ACROSS THE
JAMES RIVER VALLEY INTO CENTRAL NORTH DAKOTA TONIGHT. WILL NEED
TO MONITOR VISIBILITIES IN CASE A DENSE FOG ADVISORY IS NEEDED FOR
THE JAMES VALLEY OR OTHER AREAS THIS EVENING. ALSO...MODELS
HINTING RATHER STRONGLY AT LIGHT PRECIPITATION OVER MY EAST. WITH
DRY AIR ALOFT OPTED TO MAINTAIN A MENTION OF FREEZING DRIZZLE WITH
THE STRATUS AND FOG UNTIL WE BECOME SATURATED OVERNIGHT.
POPS ON TRACK WITH INCREASING CHANCES FOR PRECIPITATION IN THE
FORM OF RAIN SOUTHWEST AND A MIX NORTHWEST THIS AFTERNOON AND
EVENING...EVENTUALLY CHANGING TO ALL SNOW BY LATE EVENING. SNOW
CONTINUES ACROSS THE WEST AND EVEN REDEVELOPS ON MONDAY AS A
DEFORMATION ZONE AND ANOTHER MID LEVEL IMPULSE IMPACT THE AREA.
WITH CAA SNOW RATIOS WILL SUPPORT ACCUMULATING SNOWFALL OF 1 TO
NEAR 4 INCHES ACROSS THE SOUTHWEST. COMBINED WITH 15-25KTS OF WIND
ON THE BACKSIDE OF THE SFC LOW...OPTED TO HOIST A WINTER WEATHER
ADVISORY STARTING 06Z TONIGHT THROUGH 12Z TUESDAY.
ACROSS THE SOUTHEAST ON MONDAY...THE STORM SYSTEM PUSHING
SOUTHEAST TONIGHT WILL BE OVER WESTERN IOWA MONDAY...WRAPPING A
TROWAL BACK NORTHWEST AND THEN SOUTHWARD THROUGH THE EASTERN
DAKOTAS...INCLUDING THE JAMES RIVER VALLEY. TWO TO FOUR INCHES
WILL BE POSSIBLE THERE. WILL CONTINUE WITH THE SPS FOR THIS AREA
FOR NOW AND LET THE MID CREW DIGEST NEWER MODEL DATA. STILL SOME
UNCERTAINTY WITH QPF AND PLACEMENTS WITH MODELS NOT 100 PERCENT IN
AGREEMENT JUST YET.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 312 PM CST SUN DEC 21 2014
WINTER WEATHER MONDAY INTO TUESDAY...IMPACTING EARLY CHRISTMAS
TRAVEL FOR MUCH OF NORTH DAKOTA.
THE CURRENT MODEL SUITE PROVIDES GOOD AGREEMENT ON A STRONG LOW
PRESSURE SYSTEM BOTTOMING OUT OVER THE CENTRAL NORTHERN
PLAINS...KEEPING MUCH OF THE PRECIPITATION TO THE SOUTH AND EAST OF
NORTH DAKOTA. GOOD MODEL CONSENSUS ON TRACKING... THE SYSTEM IS
PROJECTED TO SLIDE SOUTH OVER NEBRASKA...THEN BEGIN TO TRACK
NORTHEASTWARD BY MONDAY NIGHT. AS THE SYSTEM TRACKS
NORTHEAST...BETWEEN TWO AND THREE INCHES OF SNOW IS FORECAST FOR
EASTERN AND SOUTHERN PORTIONS OF NORTH DAKOTA. OTHER AREAS COULD
RECEIVE UP TO AN INCH. BREEZY NORTHWESTERLY WINDS ARE ALSO FORECAST
ACROSS MUCH OF THE STATE...CREATING THE POTENTIAL FOR REDUCED
VISIBILITIES AND HAZARDOUS TRAVEL CONDITIONS.
SEASONAL TEMPERATURES ARE EXPECTED THROUGH MUCH OF THE EXTENDED.
THOUGH...ARCTIC LOW PRESSURE IS PROJECTED TO BEGIN SAGGING SOUTHWARD
FRIDAY...PRODUCING BELOW AVERAGE TEMPERATURES FRIDAY INTO SUNDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1246 AM CST MON DEC 22 2014
HAZARDS TO AVIATION TONIGHT INVOLVE LOW IFR CONDITIONS WITH
FREEZING DRIZZLE CENTRAL AND EAST AND RAIN CHANGING TO SNOW WITH A
WINTRY MIX OF FREEZING RAIN AND SLEET WEST. WIDESPREAD IFR
CONDITIONS WILL PREVAIL STATEWIDE. SNOW AND BLOWING SNOW SOUTHWEST
WILL IMPACT KDIK WITH GUSTS TO 35 KTS AND VSBYS 1 MILE IN SNOW AND
BLOWING SNOW MONDAY AFTERNOON.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 AM CST /5 AM MST/ TUESDAY FOR
NDZ017-031>033-040-041-043-044.
&&
$$
UPDATE...JV
SHORT TERM...NH
LONG TERM...AC
AVIATION...JV
AREA FORECAST DISCUSSION
NWS NORMAN OK
1041 PM CST SUN DEC 21 2014
.DISCUSSION...
AVIATION DISCUSSION FOR THE 06Z TAFS IS BELOW.
&&
.AVIATION...
CONFIDENCE REMAINS LOW THROUGH 18Z...THEN IS HIGH AFTERWARDS.
THE BIGGEST CHANGES TO THE PREVIOUS TAFS WERE TO DECREASE THE
DURATION OF IFR CONDITIONS NEAR KLAW...KCSM...AND KHBR. MAINLY
IFR CONDITIONS WILL CONTINUE EAST OF KGAG-KCSM-KLAW UNTIL A
SURFACE TROUGH MOVES THROUGH THE AREA. DOUBT CONDITIONS WILL
WORSEN TO AIRPORT MINIMUMS EXCEPT KGAG.
-DZ MAY CONTINUE NEAR KPNC THROUGH 18Z. A FEW -SHRA MAY MOVE
ACROSS OKLAHOMA 08-18Z...BUT DID NOT MENTION IN TAFS AS COVERAGE
SHOULD BE TOO SPARSE TO DIRECTLY AFFECT ANY GIVEN SITE.
A SURFACE TROUGH WILL BRING GUSTY NORTHWEST WINDS AND IMPROVING
CONDITIONS. THIS TROUGH WILL REACH NORTHWESTERN OKLAHOMA AROUND
10Z...KSPS AND KLAW 11-13Z...KOKC AROUND 15Z...AND KPNC AROUND
17Z. ALL SITES ARE EXPECTED TO BECOME VFR BY 18Z. WINDS WILL
DIMINISH AROUND 23Z.
MBS
&&
.PREV DISCUSSION... /ISSUED 949 PM CST SUN DEC 21 2014/
UPDATE...
THE AREAS OF DRIZZLE TODAY HAVE SHIFTED OUT OF THE FORECAST AREA
AS NO OBSERVATIONS SITES ARE REPORTING DRIZZLE ANY MORE. MAY SEE
SOME REDEVELOPMENT OF DRIZZLE LATER SINCE NAM SHOWS SOME RISING
MOTION AT THE TOP OF THE MOIST LAYER OVERNIGHT... BUT SIGNAL IS
NOT AS STRONG AS IN PREVIOUS DAYS. SIGNAL IS ALSO NOT AS STRONG AS
FOR FOG REDUCING VISIBILITIES TOO MUCH IN MOST AREAS... ALTHOUGH
THE RAP AND HRRR SHOW AN AREA OF FOG TRANSLATING SOUTHEAST ACROSS
WEST CENTRAL AND SOUTHWEST OKLAHOMA EARLY MONDAY MORNING JUST
BEHIND A WIND SHIFT MOVING ACROSS THAT AREA. HAVE EXPANDED THE
AREA THAT MENTIONS FOG TO INCLUDE THIS REGION... BUT OTHERWISE
HAVE CHANGED THE DESCRIPTOR FOR THE FOG/DRIZZLE FROM AREAS TO
PATCHY SINCE THE COVERAGE IS NOT EXPECTED TOO WIDESPREAD.
PREV DISCUSSION... /ISSUED 256 PM CST SUN DEC 21 2014/
DISCUSSION...
DRIZZLE HAS DEVELOPED THE PAST HOUR OR SO ACROSS CENTRAL PORTIONS
OF OKLAHOMA AND WILL LIKELY CONTINUE WELL INTO THE EVENING BEFORE
SHIFTING TO THE NORTH AND EAST OF CWA. COLD FRONT EXPECTED TO
ENTER NORTHWEST OKLAHOMA LATE TONIGHT AND PROGRESS QUICKLY OVER
THE REGION TOMORROW MORNING. THIS WILL HELP SCOUR OUT THE
PERSISTENT LOW CLOUDS AND FOG...BUT WE WILL HAVE TO DEAL WITH FAIR
AMOUNT OF MID AND HIGH LEVEL CLOUD COVER THROUGH TUESDAY. AS FAR
AS PRECIPITATION ASSOCIATED WITH THE FRONT AND LARGE UPPER TROUGH
THAT WILL SKIRT THE REGION...MOST OF ANY PRECIP WILL BE OVER
NORTHERN TEXAS AND FAR SOUTHERN OKLAHOMA LATE MONDAY INTO EARLY
TUESDAY AS STRONG JET ROUNDS BASE OF TROUGH AND INTERACTS WITH
ELEVATED FRONTAL SURFACE. COLD CORE SIGNAL BEING PROGD TO AFFECT
FAR NORTHWEST OKLAHOMA TUESDAY IN THE FORM OF VERY LIGHT SHOWERS
POSSIBLY MIXED WITH OR CHANGING TO LIGHT SNOW. WE WILL MENTION A
CHANCE OF SPRINKLES OR FLURRIES. WRF MOST AGGRESSIVE WITH THIS
ACTIVITY...AND VERY LIKELY OVERDONE. ECM KEEPS PRECIP UP IN
KANSAS WITH THE GFS IN BETWEEN.
OTHER THAN THE SMALL AREAS OF LIGHT PRECIP...WINDS AND TEMPS WILL
BE THE MAIN SENSIBLE IMPACTS NEXT SEVERAL DAYS...ALONG WITH A
MAJORITY OF THE REGION GETTING TO SEE THE SUN. BREEZY TOMORROW
MAINLY NORTHERN OKLAHOMA BEHIND THE FRONT. COOL WITH STRONG
NORTHWEST WINDS EXPECTED AGAIN TUESDAY...FOLLOWED BY WARMER WITH
GUSTY SOUTHWEST WINDS CHRISTMAS DAY. BACK TO COOLER AND GUSTY
NORTH WINDS FRIDAY. CHANCES FOR APPRECIABLE SUNSHINE WILL INCREASE
WEDNESDAY INTO NEXT WEEKEND.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 42 57 36 45 / 10 10 10 10
HOBART OK 38 58 35 46 / 10 0 10 10
WICHITA FALLS TX 42 62 39 50 / 10 0 20 10
GAGE OK 35 54 31 41 / 10 0 10 10
PONCA CITY OK 42 54 33 44 / 20 10 10 10
DURANT OK 45 60 41 51 / 10 10 20 20
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
26/17/17
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1147 PM CST SUN DEC 21 2014
.UPDATE...
ISSUED AT 935 PM CST SUN DEC 21 2014
HAVE OVERHAULED POPS AND WEATHER SOME MAINLY TO SLOW DOWN THE
SPREAD OF PRECIPITATION SPRE4D OVER THE NORTHERN PART OF THE AREA
AND TO LOWER THE OVERALL CHANCE FAR WEST/NORTHWEST. STILL...LIGHT
RAIN AT MID EVENING WAS SPREADING OVER THE MISSOURI RIVER AREA AND
SHOULD CONTINUE TO DEVELOP NORTHEAST THROUGH THE NIGHT. SLIGHT
ADJUSTMENTS TO TEMPERATURES AND TO THE NATURE OF ANY SLEET/SNOW
MIXTURE FAR NORTH AND WEST LATER TONIGHT. OVERALL HOWEVER NOT TOO
MUCH CHANGE....WITH MOST OF THE PRECIPITATION TONIGHT STILL BEING
LIGHT RAIN.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 323 PM CST SUN DEC 21 2014
CLEARING LINE HAS MADE SOME PROGRESS EAST THIS AFTERNOON. HOWEVER BY
LATE THIS AFTERNOON AND EVENING EXPECT THE LOW STRATUS TO RETURN
NORTHWEST AND COVER MUCH OF THE AREA YET AGAIN. HRRR AND RAP
GUIDANCE HAVE BEEN DOING PRETTY WELL THE PAST FEW NIGHTS...AND
SUGGEST DENSE FOG WILL PROBABLY NOT BE AS BIG OF AN ISSUE TONIGHT. A
STRONG UPPER WAVE WILL DIVE SOUTHEAST INTO THE PLAINS TONIGHT. STILL
QUITE THE SPREAD AMONG MODEL SOLUTIONS. NAM AND GFS ARE FURTHER
SOUTH WITH THE SYSTEM THAN THE ECMWF. ECMWF HAS BEEN THE MOST
CONSISTENT AND THE PARALLEL UPGRADED GFS IS MORE IN LINE WITH THE
ECMWF SOLUTION. THUS DECIDED TO WEIGH HEAVILY IN THAT DIRECTION FOR
THIS FORECAST. LIFT AHEAD OF THE WAVE WILL LIKELY GENERATE
PRECIPITATION TONIGHT...DEVELOPING IN THE WEST THIS EVENING...AND
SPREADING EAST THROUGH THE NIGHT. BASED ON MODEL SOUNDINGS AND
CONSENSUS RAW TEMPERATURES...BELIEVE THIS WILL MAINLY BE RAIN.
ALTHOUGH COULD SEE SOME SLEET MIXED IN...MAINLY WEST OF THE JAMES
RIVER.
MONDAY IS WHEN THE MODEL DIFFERENCES BEGIN TO HAVE A BIGGER IMPACT
ON THE FORECAST. THE FAVORED ECMWF AND PARALLEL GFS SOLUTION RESULTS
IN A DRY SLOT OVER MUCH OF THE CWA. THE MAJORITY OF THE WRAP AROUND
SNOW ASSOCIATED WITH THE DEVELOPING TROWAL SHOULD STAY NORTHWEST OF
THE CWA. DO THINK LOCATIONS FROM HURON TO CHAMBERLAIN COULD GET IN
ON SOME OF THIS ACTIVITY THOUGH. SOUNDINGS SUGGEST THAT BY MONDAY
ANY WARM LAYER IS SURFACE BASED...SUGGESTING EITHER RAIN OR SNOW
DEPENDING ON SURFACE TEMPERATURE. RAW MODEL CONSENSUS OF
TEMPERATURES SUGGESTS PTYPE STAYS PREDOMINATELY RAIN EAST OF THE
JAMES RIVER INTO THE AFTERNOON...WITH THE RAIN SNOW MIX GETTING TO
INTERSTATE 29 BY 0Z. BUT AS MENTIONED...MUCH OF THE CWA SHOULD SEE
VERY LIMITED QPF THROUGH THE DAY HOURS...WITH JUST SOME RAIN IN THE
FAR EAST AND AN INCH OR TWO OF SNOW FROM BRULE TO WESTERN BEADLE
COUNTY. WILL NEED TO MONITOR MODEL TRENDS...BECAUSE IF THE NAM AND
OPERATIONAL GFS FURTHER SOUTH SOLUTION VERIFIES...MORE OF THE CWA
WOULD SEE PRECIP ON MONDAY. BUT EVEN THEN THE WARM LOW LEVEL
TEMPERATURES WOULD LIKELY KEEP MOST AREAS RAIN FOR A MAJORITY OF THE
DAY KEEPING ANY SNOW ACCUMS DOWN.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 323 PM CST SUN DEC 21 2014
MONDAY NIGHT INTO TUESDAY WILL BE A PERIOD WHERE THE SYSTEM HAS
SLOWED DOWN JUST A BIT AND A FAIRLY PERSISTENT TROWAL SETS UP.
STRONG NORTH TO NORTHWEST WINDS WILL GRADUALLY DEVELOP THROUGH THE
DAY SO IT IS STARTING TO LOOK LIKE WE MAY NEED AND ADVISORY FOR SNOW
AND BLOWING SNOW MONDAY NIGHT INTO TUESDAY. MODELS STILL HAVE JUST
ENOUGH DISAGREEMENT AND THE WORST CONDITIONS LOOK TO BE LATE THIRD
PERIOD INTO 4TH PERIOD SO WILL HOLD OFF ON ISSUING ANY HEADLINES BUT
IF THIS EVENINGS MODELS COME IN SIMILAR WILL LIKELY NEED SOMETHING.
MONDAY EVENING WILL START OFF RELATIVELY MILD IN THE SOUTHEAST WITH
TEMPERATURES ABOVE FREEZING SO A BETTER CHANCE FOR RAIN IN NORTHWEST
IOWA BEFORE MIDNIGHT BUT BY ABOUT 11PM TO MIDNIGHT SHOULD BE COLD
ENOUGH FOR SNOW. NO CONCERNS RIGHT NOW OF MIXED PRECIPITATION MONDAY
NIGHT AS THE WARM LAYER IS AT THE GROUND SO SHOULD BE EITHER RAIN OR
SNOW. WENT AHEAD AND INCREASED POPS TONIGHT INTO TUESDAY AND
INCREASED QPF AMOUNTS SOME SO THAT BY TUESDAY EVENING SO THAT MUCH
OF THE AREA SHOULD SEE 2 TO 4 INCHES WITH THE JAMES VALLEY WEST
SEEING THE BEST CHANCE AT APPROACHING 4 INCHES. AGAIN...WITH 2 TO 4
INCHES OF SNOW AND 20 TO 35 MPH WINDS ON TUESDAY AND TUESDAY NIGHT
HAZARDOUS TRAVEL IS LOOKING MORE LIKELY TUESDAY INTO WEDNESDAY.
BY WEDNESDAY EVERYTHING SHOULD BE TO THE EAST OF THE AREA AND WINDS
WILL DIMINISH THROUGH THE DAY. CLOUD COVER SHOULD ALSO BREAK UP A
BIT...AT LEAST GETTING DOWN TO MOSTLY CLOUDY. WITH FRESH SNOW ON THE
GROUND EXPECTING HIGHS MAINLY IN THE 20S.
IN THE OUTER PERIODS (THURSDAY THROUGH SUNDAY)...STILL AN
INTERESTING SYSTEM COMING THROUGH ON THURSDAY NIGHT INTO FRIDAY. THE
12Z GFS SEEMED A BIT OUT TO LUNCH BUT THE 12Z ECMWF AND THE 12Z
PARALLEL GFS BOTH AGREED WELL AND SHOWED SOME CONSISTENCY FROM
YESTERDAYS RUNS. UNFORTUNATELY THE SUPERBLEND IS POLLUTED WITH THE
12Z GFS SO POPS CAME IN MUCH LOWER. HAVING TROUBLE COLLABORATING
HIGHER POPS BUT RIGHT NOW ANTICIPATE THAT POPS WILL NEED TO BE
INCREASED FOR ESPECIALLY THURSDAY NIGHT. AFTER THIS STARTING TO LOOK
LIKE A PERIOD OF COLDER WEATHER WILL SETTLE IN AS A LARGE SCALE
TROUGH SETS UP NORTHERLY FLOW ALOFT INTO THE NORTHERN ROCKIES AND
NORTHERN PLAINS. SO ANTICIPATING HIGHS IN THE TEENS AND 20S FRIDAY
INTO SUNDAY WITH LOWS IN THE SINGLE DIGITS...POSSIBLY DIPPING BELOW
ZERO ASSUMING PARALLEL AND ECMWF ARE MORE ON TARGET. SO WENT AHEAD
AND DROPPED SUPERBLEND LOWS ABOUT 2 TO 4 DEGREES IN MOST LOCATIONS
SATURDAY MORNING AND SUNDAY MORNING.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 1147 PM CST SUN DEC 21 2014
LARGELY EXPECT IFR CIGS TO DOMINATE THROUGH THE PERIOD NEAR/EAST OF
THE JAMES RIVER...THOUGH WILL LIKELY SEE BRIEF IMPROVEMENT TO LOWER
END MVFR...AND/OR DETERIORATION TO LIFR AT TIMES. DID INCLUDE SOME
POTENTIAL TIMING FOR THESE CATEGORY CHANGES...THOUGH CONFIDENCE IS
ON THE LOW SIDE.
AREA OF LIGHT RAIN LIFTING NORTH INTO THE REGION AT THE START OF THE
PERIOD...WITH TEMPERATURES IN THE MID-UPPER 30S SO ICING WILL NOT BE
A FACTOR. MODELS HAVE TRENDED TOWARD A MID LEVEL DRY SLOT MOVING
INTO WESTERN/CENTRAL PORTIONS OF THE FORECAST AREA FOR MUCH OF THE
DAY MONDAY...LEADING TO VERY LIGHT...IF ANY...PRECIPITATION FOR A
LARGE PORTION OF THE TAF PERIOD. WHAT PRECIPITATION DOES FALL SHOULD
GRADUALLY TRANSITION FROM LIGHT RAIN/DRIZZLE TO LIGHT SNOW...BUT AT
THIS TIME ANTICIPATE MVFR VISIBILITY AT WORST.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...
SHORT TERM...CHENARD
LONG TERM...08
AVIATION...JH
AREA FORECAST DISCUSSION
NWS AUSTIN/SAN ANTONIO TX
1155 PM CST SUN DEC 21 2014
.UPDATE...06Z AVIATION BELOW.
&&
.AVIATION...AT 05Z IFR CEILINGS PREVAILED ALONG AND SOUTHWEST OF
A ERV-SAT-VCT LINE. EXCEPTION WAS SKC OUT AT DRT...BUT THIS
SHOULD FILL IN OVER THE NEXT HOUR OR TWO. NORTHEAST OF THIS LINE
MVFR CEILINGS PREVAILED. SHALLOW MOISTURE WILL REMAIN TRAPPED
BENEATH INVERSION OVERNIGHT...WITH SATURATION AND CLOUD DECK
LOWERING EARLY IN THE MORNING. LOOKING MORE LIKELY FOR MIX OF
IFR/LIFR CONDITIONS ACROSS SOUTHERN AND WESTERN AREAS...AND
CONTINUED TO INDICATE THIS AT SAT/SSF/DRT. IN ADDITION...PATCHY
-DZ OCCURING OVERNIGHT ALONG THE I-35 CORRIDOR. WESTERLY LOW
LEVEL FLOW WILL DEVELOP ALONG THE I-35 CORRIDOR 15Z-18Z WITH
PASSAGE OF LOW LEVEL TROUGH...WITH NORTHWEST FLOW OVER THE RIO
GRANDE AND HILL COUNTRY. THIS SHOULD RESULT IN BETTER MIXING AND
CLEARING ALONG AND WEST OF I-35 MID TO LATE MORNING...AND
EVENTUALLY VFR CONDITIONS AT ALL TAF SITES.
&&
.PREV DISCUSSION... /ISSUED 1131 PM CST SUN DEC 21 2014/
UPDATE...
UPDATED TO INCLUDE DRIZZLE MENTION THROUGH 09Z FOR I35 CORRIDOR
AND EAST DUE TO LATEST OBS. FOG IS BEGINNING TO SET IN ALONG THE
SOUTHERN RIO GRANDE VALLEY AND UP TO THE SOUTHERN PERIPHERY OF THE
ESCARPMENT. THIS IS ON TRACK WITH THE EVOLUTION DEPICTED IN THE
MODELS SO CONFIDENCE HAS INCREASED IN THE CURRENT FORECAST.
HIGH CLOUDS ARE MOVING IN FROM THE NORTHWEST IN ADDITION TO THE
LOW CEILING DEVELOPMENT SPREADING BACK WEST TOWARDS KDRT. SEEING
WINDS JUST NORTH OF THE CWA AT 15-20 MPH SUSTAINED WITH GUSTS UP
TO 25 MPH IN RESPONSE TO A TIGHTENING PRESSURE GRADIENT. FOR
NOW...THE FORECAST STILL LOOKS PRETTY GOOD FOR THE WINDS BUT IF
THEY CONTINUE TO INCREASE...MAY NEED TO UPDATE AGAIN TO ACCOUNT
FOR THIS.
TB3
PREV DISCUSSION... /ISSUED 737 PM CST SUN DEC 21 2014/
UPDATE...
LATEST IR SATELLITE SHOWS LOW LEVEL CLOUD DECK DETERIORATING WEST
OF I35 CORRIDOR. KDRT SHOWING SOME LIGHT FOG ALREADY AT 01Z.
BOTH RUC AND HRRR INDICATE ZERO DEGREE DEWPOINT DEPRESSIONS ALONG
THE RIO GRANDE UP TO KDRT AND UP ONTO THE ESCARPMENT BEGINNING
AROUND 06Z. WITH A TIGHTENING SFC GRADIENT OVER OUR WEST AND
RESULTANT WINDS IN THE 10-15 MPH RANGE ALREADY...DONT THINK FOG
WILL BE ABLE TO SET IN ON THE ESCARPMENT MUCH...HOWEVER INCLUDED
AREAS OF FOG ALONG THE RIO GRANDE VALLEY AND SOUTH OF THE
ESCARPMENT BY 09Z. ALSO UPDATED SKY GRIDS...HOURLY T...AND HOURLY
DEW T GRIDS TO CAPTURE LATEST TRENDS.
PREV DISCUSSION... /ISSUED 339 PM CST SUN DEC 21 2014/
SHORT TERM (TONIGHT THROUGH MONDAY NIGHT)...
CLEARING HAS BEEN VERY STUBBORN THIS AFTERNOON BUT AREAS OUT WEST
AND SOUTHWEST ARE FINALLY STARTING TO SHOW SOME SUNSHINE. UPPER
TROF AXIS IS OVER THE STATE RIGHT NOW WITH MORE CLOUDINESS AND
MOISTURE UPSTREAM OVER THE ROCKIES. MOST AREAS WILL CLOUD BACK UP
OVERNIGHT AND HAVE MENTIONED SOME PATCHY FOG OVER SOUTHERN AREAS.
AREAS THAT CLEAR THIS EVENING WILL HAVE A BETTER CHANCE OF GETTING
THE FOG. LOW AND MID LEVEL WIND FIELDS WILL HAVE A WESTERLY
COMPONENT ON MONDAY MEANING WARMER TEMPERATURES AND MORE SUNSHINE.
MOST AREAS SHOULD REACH INTO THE 70S. SHOULD BE A VERY PLEASANT
DAY. ALTHOUGH WE LOSE THE LOW CLOUDS TOMORROW NIGHT WE WILL STILL
HAVE SOME MID AND HIGH CLOUDS AROUND WITH THE UPSTREAM SYSTEM OVER
THE ROCKIES. LOWS MONDAY NIGHT EXPECTED TO BE IN THE 40S TO LOW
50S.
LONG TERM (TUESDAY THROUGH SUNDAY)...
WILL SEE A COLD FRONT PUSH THROUGH THE CWA EARLY TUE MORNING WHILE A
DEEP TROF DEVELOPS OVER THE CENTRAL AND SOUTHERN PLAINS. AN UPPER
WAVE WILL PUSH SE OUT OF THE ROCKIES ON TUE WITH SOME OF ITS
ENERGY STAYING OVER SOUTH CENTRAL TEXAS EARLY WED. WITH THE COLD
FRONT AND UPPER LEVEL TROFFING...LOOKS LIKE TUE WILL BE MOSTLY
CLOUDY AND COOLER. 700 MB TROF AXIS SHIFTS EAST LATE TUE NIGHT
WHICH SHOULD MEAN A CLEARING PATTERN ON WED ALTHOUGH TEMPS WILL
REMAIN COOL AS THE SURFACE HIGH REMAINS OVER WEST TEXAS AND THE
ROCKIES. THE UPPER PATTERN FLATTENS AS TEXAS IS AT THE BASE OF A
LONG WAVE TROFFING PATTERN ACROSS MOST OF THE COUNTRY BY MID WEEK.
MOISTURE LEVELS WILL REMAIN LOW FOR THU AND FRI WHICH WILL
TRANSLATE TO MOSTLY SUNNY SKIES...COOL/COLD NIGHTS...AND COOL
AFTERNOON HIGHS IN THE 60S. WILL SEE A RETURN OF MORNING LOWS IN
THE 30S MIDDLE TO THE END OF THE WEEK. ANOTHER COLD FRONT IS
FORECAST FOR FRIDAY BUT SHOULD COME THROUGH DRY AS THERE WILL BE
LITTLE TO NO MOISTURE TO WORK WITH.
&&
.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY 52 71 48 57 38 / 10 - 10 20 -
AUSTIN BERGSTROM INTL AIRPORT 51 71 47 57 37 / 10 - 10 20 -
NEW BRAUNFELS MUNI AIRPORT 50 72 49 58 38 / 10 - 10 10 -
BURNET MUNI AIRPORT 48 70 45 54 36 / 10 - 10 20 -
DEL RIO INTL AIRPORT 43 75 48 59 37 / 10 - 10 10 -
GEORGETOWN MUNI AIRPORT 50 70 46 55 36 / 10 - 10 20 -
HONDO MUNI AIRPORT 48 73 46 61 34 / 10 - 10 10 -
SAN MARCOS MUNI AIRPORT 51 72 47 57 36 / 10 - 10 10 -
LA GRANGE - FAYETTE REGIONAL 52 72 51 56 39 / 10 - 10 20 -
SAN ANTONIO INTL AIRPORT 52 73 49 59 38 / 10 - 10 10 -
STINSON MUNI AIRPORT 51 72 50 60 38 / 10 - 10 10 -
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE/AVIATION...76
SYNOPTIC/GRIDS...03
AREA FORECAST DISCUSSION
NWS AUSTIN/SAN ANTONIO TX
1131 PM CST SUN DEC 21 2014
.UPDATE...
UPDATED TO INCLUDE DRIZZLE MENTION THROUGH 09Z FOR I35 CORRIDOR
AND EAST DUE TO LATEST OBS. FOG IS BEGINNING TO SET IN ALONG THE
SOUTHERN RIO GRANDE VALLEY AND UP TO THE SOUTHERN PERIPHERY OF THE
ESCARPMENT. THIS IS ON TRACK WITH THE EVOLUTION DEPICTED IN THE
MODELS SO CONFIDENCE HAS INCREASED IN THE CURRENT FORECAST.
HIGH CLOUDS ARE MOVING IN FROM THE NORTHWEST IN ADDITION TO THE
LOW CEILING DEVELOPMENT SPREADING BACK WEST TOWARDS KDRT. SEEING
WINDS JUST NORTH OF THE CWA AT 15-20 MPH SUSTAINED WITH GUSTS UP
TO 25 MPH IN RESPONSE TO A TIGHTENING PRESSURE GRADIENT. FOR
NOW...THE FORECAST STILL LOOKS PRETTY GOOD FOR THE WINDS BUT IF
THEY CONTINUE TO INCREASE...MAY NEED TO UPDATE AGAIN TO ACCOUNT
FOR THIS.
TB3
&&
.PREV DISCUSSION... /ISSUED 737 PM CST SUN DEC 21 2014/
UPDATE...
LATEST IR SATELLITE SHOWS LOW LEVEL CLOUD DECK DETERIORATING WEST
OF I35 CORRIDOR. KDRT SHOWING SOME LIGHT FOG ALREADY AT 01Z.
BOTH RUC AND HRRR INDICATE ZERO DEGREE DEWPOINT DEPRESSIONS ALONG
THE RIO GRANDE UP TO KDRT AND UP ONTO THE ESCARPMENT BEGINNING
AROUND 06Z. WITH A TIGHTENING SFC GRADIENT OVER OUR WEST AND
RESULTANT WINDS IN THE 10-15 MPH RANGE ALREADY...DONT THINK FOG
WILL BE ABLE TO SET IN ON THE ESCARPMENT MUCH...HOWEVER INCLUDED
AREAS OF FOG ALONG THE RIO GRANDE VALLEY AND SOUTH OF THE
ESCARPMENT BY 09Z. ALSO UPDATED SKY GRIDS...HOURLY T...AND HOURLY
DEW T GRIDS TO CAPTURE LATEST TRENDS.
PREV DISCUSSION... /ISSUED 630 PM CST SUN DEC 21 2014/
UPDATE...00Z AVIATION BELOW.
AVIATION...CLEARING HAS OCCURRED LATE THIS AFTERNOON AND EARLY
EVENING ALONG THE RIO GRANDE...WITH VFR CONDITIONS NOW AT DRT.
AT 00Z OVC MVFR STRATUS DECK STRETCHES FROM JUST NORTH OF DRT TO
SAT/SSF/AUS THEN ENCOMPASSES MOST AREAS ALONG AND EAST OF I-35
ACROSS SOUTH-CENTRAL TEXAS. SHALLOW MOISTURE TRAPPED BENEATH
INVERSION WILL CONTINUE OVERNIGHT...WITH SATURATION AND CLOUD DECK
LOWERING AFTER 06Z. HAVE INDICATED IFR CONDITIONS DEVELOPING
FIRST AT SAT/SSF AFTER 06Z AND LATER AT AUS AFTER 09Z. FORECAST
SOUNDINGS AND MOS INDICATE THERE COULD BE LIFR CEILINGS AND IFR
VISIBILITY DEVELOPING ALONG THE I-35 CORRIDOR TOWARDS DAYBREAK.
FARTHER WEST...HAVE INDICATED IFR CEILINGS DEVELOPING BACK TOWARDS
DRT AROUND 12Z...ALTHOUGH CONFIDENCE IS LOWER. SOUTHWEST AND
WESTERLY LOW LEVEL FLOW SHOULD PROMOTE BETTER MIXING AND CLEARING
ALONG AND WEST OF I-35 LATE MONDAY MORNING INTO THE EARLY
AFTERNOON.
PREV DISCUSSION... /ISSUED 339 PM CST SUN DEC 21 2014/
SHORT TERM (TONIGHT THROUGH MONDAY NIGHT)...
CLEARING HAS BEEN VERY STUBBORN THIS AFTERNOON BUT AREAS OUT WEST
AND SOUTHWEST ARE FINALLY STARTING TO SHOW SOME SUNSHINE. UPPER
TROF AXIS IS OVER THE STATE RIGHT NOW WITH MORE CLOUDINESS AND
MOISTURE UPSTREAM OVER THE ROCKIES. MOST AREAS WILL CLOUD BACK UP
OVERNIGHT AND HAVE MENTIONED SOME PATCHY FOG OVER SOUTHERN AREAS.
AREAS THAT CLEAR THIS EVENING WILL HAVE A BETTER CHANCE OF GETTING
THE FOG. LOW AND MID LEVEL WIND FIELDS WILL HAVE A WESTERLY
COMPONENT ON MONDAY MEANING WARMER TEMPERATURES AND MORE SUNSHINE.
MOST AREAS SHOULD REACH INTO THE 70S. SHOULD BE A VERY PLEASANT
DAY. ALTHOUGH WE LOSE THE LOW CLOUDS TOMORROW NIGHT WE WILL STILL
HAVE SOME MID AND HIGH CLOUDS AROUND WITH THE UPSTREAM SYSTEM OVER
THE ROCKIES. LOWS MONDAY NIGHT EXPECTED TO BE IN THE 40S TO LOW
50S.
LONG TERM (TUESDAY THROUGH SUNDAY)...
WILL SEE A COLD FRONT PUSH THROUGH THE CWA EARLY TUE MORNING WHILE A
DEEP TROF DEVELOPS OVER THE CENTRAL AND SOUTHERN PLAINS. AN UPPER
WAVE WILL PUSH SE OUT OF THE ROCKIES ON TUE WITH SOME OF ITS
ENERGY STAYING OVER SOUTH CENTRAL TEXAS EARLY WED. WITH THE COLD
FRONT AND UPPER LEVEL TROFFING...LOOKS LIKE TUE WILL BE MOSTLY
CLOUDY AND COOLER. 700 MB TROF AXIS SHIFTS EAST LATE TUE NIGHT
WHICH SHOULD MEAN A CLEARING PATTERN ON WED ALTHOUGH TEMPS WILL
REMAIN COOL AS THE SURFACE HIGH REMAINS OVER WEST TEXAS AND THE
ROCKIES. THE UPPER PATTERN FLATTENS AS TEXAS IS AT THE BASE OF A
LONG WAVE TROFFING PATTERN ACROSS MOST OF THE COUNTRY BY MID WEEK.
MOISTURE LEVELS WILL REMAIN LOW FOR THU AND FRI WHICH WILL
TRANSLATE TO MOSTLY SUNNY SKIES...COOL/COLD NIGHTS...AND COOL
AFTERNOON HIGHS IN THE 60S. WILL SEE A RETURN OF MORNING LOWS IN
THE 30S MIDDLE TO THE END OF THE WEEK. ANOTHER COLD FRONT IS
FORECAST FOR FRIDAY BUT SHOULD COME THROUGH DRY AS THERE WILL BE
LITTLE TO NO MOISTURE TO WORK WITH.
&&
.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY 52 71 48 57 38 / 10 - 10 20 -
AUSTIN BERGSTROM INTL AIRPORT 51 71 47 57 37 / 10 - 10 20 -
NEW BRAUNFELS MUNI AIRPORT 50 72 49 58 38 / 10 - 10 10 -
BURNET MUNI AIRPORT 48 70 45 54 36 / 10 - 10 20 -
DEL RIO INTL AIRPORT 43 75 48 59 37 / 10 - 10 10 -
GEORGETOWN MUNI AIRPORT 50 70 46 55 36 / 10 - 10 20 -
HONDO MUNI AIRPORT 48 73 46 61 34 / 10 - 10 10 -
SAN MARCOS MUNI AIRPORT 51 72 47 57 36 / 10 - 10 10 -
LA GRANGE - FAYETTE REGIONAL 52 72 51 56 39 / 10 - 10 20 -
SAN ANTONIO INTL AIRPORT 52 73 49 59 38 / 10 - 10 10 -
STINSON MUNI AIRPORT 51 72 50 60 38 / 10 - 10 10 -
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE/AVIATION...76
SYNOPTIC/GRIDS...03
PUBLIC SERVICE/DATA COLLECTION...12
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
1015 AM EST MON DEC 22 2014
.DISCUSSION...
DEEP S/SW FLOW ACRS THE FL PENINSULA/ERN GOMEX THIS MORNING DUE TO
THE AN H100-H70 RIDGE AXIS OVER THE FL STRAITS. THESE WINDS HAVE
SHUNTED THE FRONTAL BOUNDARY THAT WAS STALLED OVER THE NRN PENINSULA
BACK INTO THE PANHANDLE...ALLOWING A SLIGHTLY DRIER AND MORE STABLE
AIRMASS TO PUSH INTO CENTRAL FL. MORNING SOUNDINGS FROM KTBW/KMFL
SHOW THE DRIER AIR BLO H80 WITH AVG DEWPOINT DEPRESSIONS BTWN 8-12C
AND AS HIGH AS 20C. RUC ANALYSIS PICKING UP ON THIS DRY AIR...
INDICATING MEAN RH VALUES THRU THE H100-H70 LYR BLO 70PCT...AS LOW
AS 55PCT IN THE H100-H85 LYR OVER THE TREASURE COAST.
ALOFT...A 100-120KT H30-H20 JET STREAK LIFTING ACRS THE DEEP
SOUTH/MID ATLC REGION HAS PULLED ALMOST ALL OF THE LCL DYNAMIC
FORCING NORTH OF CENTRAL FL. VORTICITY IS ALMOST NONEXISTENT THRU
THE H85-H30 LYR. A THIN BAND OF UPR LVL DIVERGENCE OVER THE ERN
GOMEX HAS INDUCED A LCL AREA OF CONVECTION...BUT THE MEAN FLOW WILL
CARRY ANY PRECIP ALONG AND N OF THE I-4 CORRIDOR. INDEED...BOTH
HRRR/LCL WRF MODELS GENERATE LITTLE IF ANY PRECIP OVER THE CWA...AND
ALL OF IT IN THE VCNTY OF I-4.
DESPITE BETTER INSOLATION OVER THE S...THE COMBINATION OF LOW LVL
DRY AIR AND WEAK DYNAMIC FORCING WILL PREVENT THE FORMATION OF ANY
ORGANIZED PRECIP OVER THE SRN CWA...AND ANY DEEP CONVECTION OVER THE
N. WILL SHAVE POPS BACK TO CHC/SLGT CHC FROM BREVARD/OSCEOLA COUNTY
NWD...REMOVING TSRAS IN THE PROCESS. FROM INDIAN RIVER/OKEECHOBEE
SWD...BLO MENTIONABLE POPS.
&&
.AVIATION...THRU 23/12Z
SFC WNDS:
THRU 23/00Z...S/SW 8-12KTS. AFT 23/12Z...S/SW 3-6KTS.
VSBYS/WX:
THRU 23/06Z...SLGT CHC MVFR SHRAS N OF KVRB-KLAL...INCRSG TO CHC N
OF KTIX-KISM. AFT 23/06Z...AREAS MVFR BR ALL SITES...LCL LIFR FG
VCNTY KVRB/KFPR/KLEE.
CIGS/WX:
THRU 23/00Z...BTWN FL080-100 WITH PDS MVFR BTWN FL020-030 IN PASSING
SHRAS. BTWN 23/00Z-23/06Z...BCMG MVFR BTWN FL015-025 IN -RA. AFT
23/06Z...WDSPRD IFR BTWN FL006-009 WITH AREAS LIFR BLO FL004.
&&
.MARINE...
WEAK SFC RIDGE OVER THE FL STRAITS WILL COMBINE WITH AN OPEN FRONTAL
TROF OVER N FL TO MAINTAIN A LIGHT TO GENTLE SRLY BREEZE ACRS THE
LCL ATLC THIS AFTN. DESPITE THE WEAK SFC/BNDRY LYR FLOW...DATA BUOYS
HAVE MEASURED A SMALL BUT DISCERNIBLE INCREASE IN SEAS OVER THE PAST
24HRS DUE TO THE ARRIVAL OF A 2-3FT ERLY SWELL. WARM FRONT HAS
LIFTED WELL N OF FLAGLER BEACH AND SHOWING NO SIGNS OF REVERSING
COURSE...IN ITS WAKE A LCL POCKET OF DRY AIR WILL MOVE UP FROM THE S
PENINSULA AND QUASH RAIN CHANCES S OF THE CAPE.
LITTLE CHANGE IN THE WX PATTERN AS THE HI PRES RIDGE TO THE SOUTH
HOLDS THE LINE. SEAS 2-3FT NEARSHORE AND 3-4FT OFFSHORE.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
SHORT TERM/AVIATION...BRAGAW
LONG TERM/IMPACT WX...CRISTALDI
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1046 AM EST MON DEC 22 2014
.SYNOPSIS...
UNSETTLED WEATHER IS EXPECTED THROUGH TUESDAY NIGHT AS SEVERAL
DISTURBANCES MOVE OVER THE REGION. A STRONG COLD FRONT WILL THEN
MOVE THROUGH THE AREA WEDNESDAY EVENING. DRY HIGH PRESSURE WILL
SETTLE OVER THE SOUTHEAST INTO THE WEEKEND. ANOTHER COLD FRONT
COULD SHIFT THROUGH THE AREA EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
A MUCKY PATTERN WILL CONTINUE FOR YET ANOTHER DAY AS A STRONG
WEDGE OF HIGH PRESSURE REMAINS OVER THE MID-ATLANTIC REGION AND
EXTENDS DOWN THE EASTERN SEABOARD AS FAR SOUTH AS SOUTHERN GA. A
DEEP UPPER LEVEL TROUGH OVER THE CENTRAL UNITED STATES CONTINUES
TO PROVIDE A STEADY FEED OF SHORTWAVE ENERGY ACROSS THE SOUTHEAST
STATES. INITIALLY IT SEEMED AS THOUGH THE JET DIVERGENCE WAS GOING
TO WEAKEN TODAY AND THE STRONGEST SHORTWAVE ENERGY WOULD SHIFT
NORTHEAST OF THE REGION. HOWEVER WE HAVE NOTED A FAIRLY WIDESPREAD
AREA OF RAIN MOVING OUT OF CENTRAL GA INTO OUR FORECAST AREA THIS
MORNING. THIS IS ASSOCIATED WITH A WEAK SLUG OF ISENTROPIC OMEGA
THAT THE 12Z NAM FINALLY PICKED UP ON. THE LATEST HRRR HAS ALSO
CAUGHT ONTO THE INLAND PRECIP WHICH SHOULD PROGRESS NORTHEAST
THROUGH THE AREA THIS AFTERNOON. SIGNIFICANT CHANGES TO THE POP
GRIDS WERE IN ORDER THIS MORNING. WE ARE NOW CARRYING LIKELY OR
CATEGORICAL POPS OVER MANY LAND AREAS THROUGH EARLY AFTERNOON...
GRADUALLY TAPERING BACK LATE THIS AFTERNOON ONCE THE BEST FORCING
MOVES AWAY TO THE NORTHEAST. DENSE OVERCAST AND STEADY RAIN WILL
KEEP TEMPERATURES FAIRLY STEADY IN THE UPPER 40S TO LOWER 50S.
SOUNDINGS SHOW LOW-MID 50S AIR AT THE SURFACE TODAY AND THIS
EVENING AND MID 60S AIR AT 300-400 FT WHICH IS PRIME FOR STRATUS
BUILDING DOWN GIVEN A SETUP WITH LIGHTER WINDS IN THE BOUNDARY
LAYER. THE STORY TONIGHT SHOULD BE FOG...PROBABLY DENSE IN MANY
AREAS. WE HAVE ADDED DENSE FOG POTENTIAL TO THE HAZARDOUS WEATHER
OUTLOOK. OTHERWISE...THE WARM FRONT MAY MOVE INTO THE OUR SOUTHERN
GEORGIA ZONES BY DAYBREAK ON TUE AND A CONTINUATION OF PERIODIC
DRIZZLE AND MAINLY LIGHT RAIN SHOWERS. MID LEVELS LOOK PRETTY
UNSTABLE BUT ELEVATED THUNDER RISK IS PRETTY LOW AS MODELS SHOW
MID LEVEL NVA AND SOMEWHAT DRIER AIR ALOFT. TEMPS OVERNIGHT SHOULD
BE STEADY AND EVEN RISE LATE. POPS MAINLY IN THE CHANCE RANGE.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
TUESDAY AND WEDNESDAY...A LARGE SYNOPTIC SCALE TROUGH OF LOW PRESSURE
WILL DIG OVER THE CENTRAL UNITED STATES...SPAWNING A SFC LOW OVER
THE NORTHERN GULF OF MEXICO TUESDAY THAT QUICKLY DEEPENS AND LIFTS
NORTH/NORTHEAST WITH A COLD FRONT EXTENDING SOUTHWARD INTO WEDNESDAY.
A STRONG H5 SHORTWAVE ROUNDING THE BASE OF THE HIGH AMPLITUDE TROUGH
AS WELL AS A STRONG LOW/MID/UPPER LVL JET WILL LIKELY FORCE THE
SOUTHWARD EXTENDING COLD FRONT TO THE EAST...EVENTUALLY PUSHING IT
THROUGH THE FORECAST AREA LATE WEDNESDAY AFTERNOON INTO EARLY
WEDNESDAY NIGHT.
AHEAD OF THE COLD FRONT...A DEEP PLUME OF MOISTURE CHARACTERIZED BY
PWATS UP TO 1.8-1.9 INCHES WILL ADVECT TO THE AREA AS A WARM FRONT
BEGINS TO LIFT NORTH AND ENCOUNTERS THE PERSISTENT WEDGE INLAND.
WIDESPREAD SHOWERS WILL THEREFORE REMAIN IN THE FORECAST FOR MOST
AREAS. MODELS NOW SUGGEST THE WARM FRONT WILL LIFT A BIT FURTHER
NORTH ON TUESDAY THAN PREVIOUSLY NOTED...TRYING TO SCOUR OUT WHAT IS
LEFT OF WEDGE OF HIGH PRESSURE INLAND. HOWEVER...WE STILL BELIEVE
THIS IS A BIT AGGRESSIVE WITH THE WEDGE CURRENTLY IN PLACE SO HAVE
MAINTAINED TEMPS A FEW DEGREES BELOW GUIDANCE...ESPECIALLY INLAND
WHERE THE WEDGE SHOULD HOLD DURING PEAK HEATING HOURS TUESDAY
AFTERNOON. GIVEN THIS SCENARIO...SLIGHT CHANCES OF THUNDERSTORMS
WILL REMAIN IN THE FORECAST TUESDAY AFTERNOON/EVENING WHERE SBCAPES
APPROACH 800 J/KG AND MODEST MID LVL LAPSE RATES OCCUR SOUTH OF THE
WARM FRONT. WE COULD SEE SOME ENHANCEMENT TO THUNDERSTORM ACTIVITY
AS SEVERAL MID LVL WAVES OF ENERGY ADVANCE OVER THE AREA TUESDAY
AFTERNOON AND/OR EVENING. THUNDERSTORMS MAY ALSO NEED TO BE INCLUDED
IN FUTURE FORECASTS FOR INLAND AREAS SHOULD ELEVATED INSTABILITY
CONTINUE TO INCREASE OVER THE WEDGE. IN GENERAL...AFTERNOON HIGH
TEMPS SHOULD RANGE IN THE LOW/MID 60S INLAND TO UPPER 60S IN
SOUTHEAST GEORGIA TUESDAY AFTERNOON.
AS DIURNAL HEATING IS LOST TUESDAY NIGHT...THUNDERSTORM CHANCES
SHOULD MAINLY OCCUR OFFSHORE...BUT DEEP MOISTURE WILL LIKELY
MAINTAIN WIDESPREAD SHOWERS WHILE FORCING INCREASES FROM THE
WEST. TUESDAY NIGHT TEMPS WILL BE MILD WITHIN A SOUTHERLY FLOW AHEAD
OF THE APPROACHING COLD FRONT...WITH LOWS ONLY DIPPING INTO THE
UPPER 50S TO LOWER 60S.
WIDESPREAD CLOUD COVER AND ONGOING SHOWERS SHOULD LIMIT THE OVERALL
THERMODYNAMIC ENVIRONMENT ON WEDNESDAY. HOWEVER...STRONG WIND FIELDS
JUST OFF THE SFC COULD RESULT IN SOME GUSTY WINDS CONDITIONS AS
TEMPS APPROACH 70 DEGREES WEDNESDAY AFTERNOON. A SLIGHT CHANCE OF
THUNDERSTORMS WILL REMAIN IN THE FORECAST FOR ALL AREAS GIVEN THE
AMOUNT OF MID/UPPER LVL FORCING SHIFTING OVER THE REGION. HOWEVER
THE BEST CHANCES OF THUNDERSTORMS SHOULD OCCUR AS THE COLD FRONT
PUSHES INTO THE AREA WEDNESDAY EVENING INTO EARLY WEDNESDAY NIGHT.
GUSTY WINDS SHOULD CONTINUE FOR A FEW HOURS WEDNESDAY NIGHT AS
STRONG COLD AIR ADVECTION OCCURS BEHIND THE FRONT. CONDITIONS WILL
THEN QUICKLY DRY OUT FROM WEST TO EAST LATE WEDNESDAY NIGHT AS HIGH
PRESSURE BEGINS TO PUSH INTO THE REGION.
THURSDAY...MUCH DRYER/QUIET WEATHER CONDITIONS ARE EXPECTED AS THE
MID LVL TROUGH AXIS SHIFTS OFFSHORE AND HIGH PRESSURE SETTLES OVER
THE SOUTHEASTERN UNITED STATES. DESPITE A RETURN TO MOSTLY SUNNY
SKIES...TEMPS WILL REMAIN COOLER AS COLD AIR ADVECTS OVER THE AREA.
IN GENERAL...AFTERNOON TEMPS SHOULD RANGE IN THE MID TO UPPER 50S
OVER MOST AREAS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
QUIET WEATHER WILL PREVAIL INTO THE WEEKEND AS HIGH PRESSURE BECOMES
CENTERED OVER THE SOUTHEASTERN UNITED STATES. OVERALL HIGH TEMPS
SHOULD GRADUALLY WARM EACH DAY AS HIGH PRESSURE CONTINUES TO SLIDE
EAST LATE WEEKEND...ALLOWING A LIGHT SOUTHERLY FLOW TO RETURN TO THE
AREA. IN GENERAL...TEMPS WILL REACH THE LOWER 60S ON FRIDAY...THEN
TO THE MID 60S ON SATURDAY. OVERNIGHT LOWS SHOULD RANGE IN THE THE
LOW/MID 40S INTO THE WEEKEND. THE NEXT BEST CHANCE OF PRECIP SHOULD
OCCUR EARLY NEXT WEEK WITH A COLD FRONT THAT APPROACHES THE REGION.
HOWEVER...CONFIDENCE IN TIMING AND STRENGTH OF PATTERN IS QUITE LOW
GIVEN LARGE DISCREPANCIES IN MODEL SOLUTIONS.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
KSAV...THE TERMINAL MOST LIKELY WILL REMAIN TANKED AS A STRONG WEDGE
INVERSION PERSISTS JUST OFF THE DECK AND GENERATES IFR OR LOWER
CONDITIONS THROUGH 06Z TUESDAY. IN ADDITION...MID AND UPPER LEVEL
ENERGY AND THE PROXIMITY TO A COASTAL WARM FRONT NEAR THE GULF
STREAM WILL PRODUCE PERIODS OF RAIN OR DRIZZLE.
KCHS...LIFR CONDITIONS DEVELOPING AT 09Z...DENSE FOG MAY ENSUE
AS CIGS DOWN TO 200 FT AND VSBYS AT 1 NM. THE NEXT 24 HOURS WILL
SEE LOW CIGS AND PERHAPS PERIODS OF FOGGY CONDITIONS AS STRATUS
CLOUDS REMAINED PINNED IN THE FIRST FEW HUNDRED FEET OF THE
ATMOSPHERE. OCCASIONAL DRIZZLE LIKELY WITH A CHANCE OF SHOWERS.
IFR OR LOWER CONDITIONS PREVAIL THROUGH THE TAF PERIOD.
EXTENDED AVIATION OUTLOOK...PERIODS OF MVFR OR LOWER CONDITIONS ARE
LIKELY LIKELY TUESDAY AFTERNOON INTO WEDNESDAY AFTERNOON AS A STRONG
COLD FRONT APPROACHES FROM THE WEST WITH SHOWERS AND THUNDERSTORMS.
LLWS WILL BE A POSSIBILITY TUESDAY NIGHT AS STRONGER WIND FIELDS
SHIFT OVER THE AREA IN ADVANCE OF THE FRONT. MVFR OR LOWER
CONDITIONS AND GUSTY WINDS ARE EXPECTED UNTIL THE TIME OF FRONTAL
PASSAGE SOMETIME WEDNESDAY EVENING INTO EARLY WEDNESDAY NIGHT. VFR
CONDITIONS SHOULD THEN PREVAIL BY DAYBREAK THURSDAY.
&&
.MARINE...
MARINE CONDITIONS ARE SLOWLY IMPROVING THIS MORNING. THE GRADIENT
HAS WEAKENED ENOUGH TO ALLOW THE SMALL CRAFT ADVISORIES TO DROP
OFF AROUND DAYBREAK. THE DENSE FOG IN CHARLESTON HARBOR AND
IMMEDIATE CHARLESTON COASTAL WATERS HAS LIFTED TO A LOW STRATUS
DECK. CHS PILOT OFFICE REPORTS VSBYS AROUND 3 NM AS OF 9 AM WITH
THE PORT REOPENED TO COMMERCIAL SHIPPING TRAFFIC. WE DROPPED THE
DENSE FOG ADVISORY A BIT EARLIER. TONIGHT THERE COULD BE A
RESURGENCE IN FOG AS THE STRATUS DECK BUILDS DOWN AND ANOTHER
DENSE FOG ADVISORY IS POSSIBLE.
TUESDAY...CONDITIONS SHOULD REMAIN JUST BELOW SMALL CRAFT ADVISORY
LEVELS AS A WEDGE OF HIGH PRESSURE PERSISTS INLAND WHILE A WARM
FRONT TRIES TO LIFT NORTH DURING THE AFTERNOON. SHOWERS AND/OR
THUNDERSTORMS ARE ANTICIPATED OVER THE WATERS THROUGH THE DAY. IN
GENERAL...WINDS SHOULD PEAK BETWEEN 15-20 KT WITH SEAS UP TO 3-4
FT...HIGHEST IN OFFSHORE GEORGIA WATERS.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...CONDITIONS WILL LIKELY
DETERIORATE LATE TUESDAY NIGHT INTO EARLY WEDNESDAY AS THE PRESSURE
GRADIENT TIGHTENS AND WARMER AIR PROMOTES MIXING AHEAD OF A COLD
FRONT THAT EVENTUALLY SHIFTS OVER THE WATERS WEDNESDAY
EVENING/NIGHT. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE OVER MOST
WATERS AHEAD OF THE FRONT...WHILE WINDS AND SEAS INCREASE/BUILD
WITHIN A SOUTHERLY FLOW. AT THIS TIME...CONDITIONS SHOULD REACH
SMALL CRAFT ADVISORY LEVELS FOR ALL WATERS STARTING LATE TUESDAY
NIGHT. SEAS WILL ALSO BUILD UPWARDS TO 5-8 FT INTO WEDNESDAY
AFTERNOON BEFORE THE COLD FRONT SHIFTS OFFSHORE. THERE IS STILL A
CHANCE OF GALE FORCE WIND GUSTS LATE WEDNESDAY NIGHT INTO EARLY
THURSDAY AS STRONG COLD AIR ADVECTION OCCURS BEHIND THE FRONT...BUT
CHANCES APPEAR HIGHEST IN OUTER GEORGIA WATERS. A GALE WATCH/WARNING
COULD EVENTUALLY BE NEEDED AS WINDS GUST TO 30-35 KT AWAY FROM THE
COAST.
THURSDAY AFTERNOON THROUGH SATURDAY...CONDITIONS WILL IMPROVE
QUICKLY OVER ALL WATERS AS HIGH PRESSURE BECOMES CENTERED OVER THE
SOUTHEAST. WINDS/SEAS SHOULD LOWER BELOW SMALL CRAFT ADVISORY LEVELS
FOR ALL WATERS THURSDAY AFTERNOON...THEN CONTINUE TO IMPROVE
THROUGH THE WEEKEND AS THE CENTER OF HIGH PRESSURE SLIDES OFFSHORE.
SEA FOG...MARINERS ARE ADVISED THAT LOW STRATUS DECKS AND PERIODS OF
RAIN OR DRIZZLE WILL EQUATE TO REDUCED VISIBILITIES UNTIL WEDNESDAY...
BUT THE BEST CHANCE OF CLASSIC SEA FOG COULD DEVELOP AS WARMER AIR
ARRIVES ATOP MID/UPPER 50 SHELF WATER TEMPS EARLY TUESDAY PRIOR TO
WINDS INCREASING ENOUGH TO SCOUR IT OUT TUESDAY NIGHT.
&&
.TIDES/COASTAL FLOODING...
NNE FLOW PUSHED THE CHARLESTON TIDE ABOVE 7.4 FT THIS MORNING...
MORE THAN 1 FT ANOMALY. AMAZING WHAT THE EKMAN EFFECT CAN DO TO
TIDES. THE TUESDAY MORNING HIGH TIDE IS PREDICTED AT 6.4 FT MLLW.
SIMILAR WINDS EXPECTED THEN...PERHAPS SLIGHTLY WEAKER. NEVERTHELESS
CONDITIONS LOOK PRETTY FAVORABLE FOR ANOTHER BOUT OF SHALLOW
COASTAL FLOODING SO WE ARE MENTIONING THIS IN THE HAZARDOUS
WEATHER OUTLOOK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...JRL
SHORT TERM...DPB
LONG TERM...DPB
AVIATION...
MARINE...DPB/JRL
TIDES/COASTAL FLOODING...JRL
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
904 AM CST Mon Dec 22 2014
.UPDATE...
ISSUED AT 904 AM CST MON DEC 22 2014
Made a quick update to the forecast to increase PoPs to 100
percent as light rain has already spread across much of the KILX
CWA. The exceptions are northwest of the Illinois River and
further east near the Indiana border. Based on radar trends and
latest HRRR and NAM forecasts, light rain will spread across the
remainder of the area over the next couple of hours. May see a
brief period of a rain/sleet mix northeast of I-74 near Rantoul
and Danville as the precip initially begins, but it will quickly
transition to all rain. Also made a few tweaks to hourly temps and
lowered afternoon highs by a couple of degrees due to rain and a
continued E/SE flow. Highs will reach the lower to middle 40s.
&&
.SHORT TERM...(Today)
ISSUED AT 501 AM CST MON DEC 22 2014
Strong jet (175kts) over the Pacific Northwest digging southeast
into a deepening central Plains trof this morning will eject an
initial wave into our area today bringing rain along with mild
temperatures. Low pressure is expected to consolidate over north
central Missouri by late this afternoon and then track thru
northwest Illinois early this evening. The southerly flow in advance
of the storm system will quickly saturate the lower levels of the
atmosphere with rain overspreading the area from southwest to
northeast this morning. Some weak isentropic lift and moisture
convergence early this morning has produced some spotty light
rain/drizzle over parts of central Illinois and expect that to
continue before the stronger forcing arrives later this morning.
Models suggest the strongest lift moves into our area from mid
morning thru the early evening hours, so high POPs are warranted
over most of the forecast area today. Despite the cloud cover and
precip, mild temperatures to prevail again today with afternoon
readings in the mid to upper 40s.
&&
.LONG TERM...(Tonight through Sunday)
ISSUED AT 501 AM CST MON DEC 22 2014
Increased rain chances to categorical this evening with supporting
lift of low level jet and short waves ejecting ne from
central/southern plains into IL tonight. Rain chances to diminish
from sw to ne during overnight into Tue morning as energy shifts
north of central IL Tue. Appears to be a lull in rain chances Tue
and Tue evening over much of central IL with best rain chances
shifting to our north with surface low pressure over southern WI Tue
afternoon and also to our se. Mild lows tonight of 40-45F and highs
Tue range from mid 40s over IL river valley and lower 50s in
southeast IL.
00Z models still not in good agreement with development of strong
low pressure system from northwestern Gulf of Mexico and deepening
nne across the ohio river valley Wed. NAM model appears is dry over
IL Tue night and Wed but feel its low pressure track is too far east
near the foothills of the Appalachians. Will use a blend of the
ECMWF/GEM and GFS models for the storm system during midweek. Have
precipitation chances spreading back northward across central IL
overnight Tue night into Wed and diminishing from west to east by
overnight Wed night. Warm enough for rain Tue evening, then mixing
with and gradually changing to light snow later Tue night into Wed
from west to east. Deformation band of light snow accumulations
likely to set up on back side of storm system, though placement of
this band is still too difficult to pinpoint down. WPC keeps snow
accumulations less than 1 inch over central/eastern IL on
Wed/Christmas eve. Cooler highs Wed in the upper 30s to near 40F
eastern IL and will likely slip during the afternoon with increasing
WNW winds.
Christmas Day still looks dry with return of some sunshine as strong
storm system lifts into Quebec and 1025 mb surface high pressure
over gulf of mexico ridges northward into the ohio river valley.
Highs in the lower 40s Thu/Christmas Day, so any snow that does fall
Wed will likely melt.
Models have another low pressure taking a track more nw of central
IL Friday and lifting into the western Great Lakes Friday night.
Have small chances of light precipitation Fri/Fri night and then dry
for the weekend. Models showing yet another southern low pressure
system over gulf of Mexico Sat night/Sunday but for now will keep
precipitation chances south of central IL.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
ISSUED AT 515 AM CST MON DEC 22 2014
Deteriorating conditions expected across the area this morning
as a storm system tracks into the region. Mostly VFR cigs being
reported early this morning but expect those to transition to
MVFR and then IFR from south to north after 15z this morning as
rain increases in coverage over our area. We expect IFR to LIFR
conditions this afternoon into tonight as the rain continues on
and off thru 00z. In the 03z-06z, the rain is expected to taper
off with a lull in the precip after 06z as the storm system shifts
north of our area overnight. Surface winds will be east to southeast
today at 10 to 15 kts with a few gusts around 20 kts later this
morning into the afternoon hours. Southeast winds of 10 to 15 kts
can be expected tonight.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Barnes
SHORT TERM...Smith
LONG TERM...07
AVIATION...Smith
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
948 AM EST MON DEC 22 2014
.UPDATE...
NEAR TERM FOR THE REST OF TODAY HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 327 AM EST MON DEC 22 2014
AN UPPER TROUGH AND A COUPLE OF AREAS OF LOW PRESSURE WILL BRING
RAIN TO CENTRAL INDIANA TODAY INTO WEDNESDAY...WITH PERHAPS SOME
SNOW WEDNESDAY NIGHT. ANOTHER SYSTEM WILL BRING ADDITIONAL CHANCES
FOR PRECIPITATION FRIDAY AND SATURDAY. NEAR TO ABOVE AVERAGE
TEMPERATURES THIS WEEK WILL RETURN TO COOLER THAN AVERAGE FOR THE
WEEKEND.
&&
.NEAR TERM.../REST OF TODAY/
ISSUED AT 948 AM EST MON DEC 22 2014
.UPDATE...RAISED RAIN CHANCES A LITTLE OVER CENTRAL AND WESTERN
SECTIONS AS RADAR LOOPS HAS SHOWN A PRETTY GOOD PROGRESSION OF LIGHT
RAIN INTO OUR WESTERN SECTIONS AND MODELS SHOW THIS TREND CONTINUING
THIS AFTERNOON. OTHERWISE...ONLY MINOR TWEAKS MADE TO GRIDS AS
PREVIOUS FORECAST SEEMS TO BE ON TRACK.
PREVIOUS NEAR TERM DISCUSSION FOLLOWS...
ISENTROPIC LIFT WILL INCREASE TODAY AS AN UPPER TROUGH AND SURFACE
WARM FRONT MOVE TOWARD CENTRAL INDIANA. BEST FORCING ARRIVES LATE IN
THE DAY WHEN 850MB WINDS APPROACH 50KT AND AN UPPER JET MOVES CLOSER
TO THE AREA.
ANY PRECIPITATION WILL HAVE TO FIGHT THE DRY LOWER LEVELS OF THE
ATMOSPHERE INITIALLY. SOUTHEAST WINDS AT THE SURFACE WILL AID IN
KEEPING THE LOWER LEVELS DRY. THUS IT WILL TAKE THE ATMOSPHERE A
WHILE TO MOISTEN UP.
GIVEN THE ABOVE...WENT HIGHEST POPS TODAY AT THE END OF THE TODAY
PERIOD. GRADUALLY INCREASED POPS DURING THE DAY. BY LATE DAY WENT
LIKELY POPS FAR WEST...CHANCE CENTRAL...AND SLIGHT CHANCE FAR EAST.
CLOUDS WILL INCREASE/THICKEN THROUGH THE DAY. A BLEND OF MODELS
LOOKS BEST FOR HIGH TEMPERATURES...AND THIS ENDS UP NEAR TO A LITTLE
COOLER THAN MOS SUGGESTS.
&&
.SHORT TERM.../TONIGHT THROUGH WEDNESDAY NIGHT/
ISSUED AT 327 AM EST MON DEC 22 2014
FOCUS IS ON PRECIPITATION CHANCES THROUGH THE PERIOD. THREW OUT THE
NAM AS ITS SOLUTION OF BRINGING A SURFACE LOW NEAR THE APPALACHIANS
LOOKS UNREALISTIC. GFS/ECMWF/CANADIAN MODELS ARE SIMILAR AND LOOK
MORE REASONABLE...SO USED A BLEND OF THEIR SOLUTIONS.
RAIN WILL CONTINUE TO OVERSPREAD CENTRAL INDIANA TONIGHT WITH FIRST
A WARM FRONT THEN A COLD FRONT MOVING THROUGH THE AREA. 850MB JET
WILL PROVIDE GOOD MOISTURE AND FORCING...AND UPPER TROUGH/UPPER JET
WILL BRING ADDITIONAL FORCING. THUS WENT CATEGORICAL POPS ALL AREAS
TONIGHT. LOWERED POPS OVERNIGHT AS SOME DRIER AIR WORKS IN BEHIND
THE COLD FRONT.
MODELS NOW SHOWING A DRY SLOT ACROSS CENTRAL INDIANA FOR MUCH OF
TUESDAY. THIS SEEMS REASONABLE WITH FIRST SURFACE AND UPPER SYSTEMS
MOVING OFF THE NORTH...AND NEXT UPPER LOW AND SURFACE LOW STILL
ORGANIZING TO THE SOUTH/SOUTHWEST. HOWEVER DO NOT BELIEVE THE VERY
DRY GFS GIVEN THAT ANY WEAK UPPER IMPULSES COULD GENERATE SOME
SHOWERS.
THUS WENT MAINLY CHANCE POPS THROUGH THE DAY TUESDAY ACROSS THE
AREA. KEPT HIGHER POPS EAST DURING THE MORNING TO ACCOUNT FOR RAIN
ALONG THE EXITING SURFACE FRONT.
TUESDAY NIGHT POPS WILL INCREASE ONCE AGAIN AS THE NEXT SYSTEM
APPROACHES FROM THE SOUTH. BY 06Z WENT LIKELY POPS MOST AREAS.
ON WEDNESDAY A SURFACE LOW WILL MOVE THROUGH THE AREA. MODELS STILL
UNCERTAIN ON EXACT PATH...BUT IT SHOULD BE IN THE GENERAL AREA OF
CENTRAL INDIANA TO WESTERN OHIO. WENT HIGH END LIKELY POPS...AND MAY
NEED TO UP THEM TO CATEGORICAL AS WE GET CLOSER.
WITH THE MORE WESTERN TRACKS OF THE MODELS GAINING FAVOR /GFS
ENSEMBLE MEAN AND PARALLEL GFS ARE FARTHER WEST THAN OPERATIONAL GFS
AND ECMWF/ FEEL THAN RAIN WILL BE THE PRIMARY PRECIPITATION TYPE
THROUGH THE DAY WEDNESDAY. WENT WITH CHANCE OF SNOW MIXING IN ACROSS
ROUGHLY THE WEST HALF OF CENTRAL INDIANA IN THE LATE AFTERNOON AS
COLDER AIR STARTS TO WORK IN.
MOST OF THE FORCING WILL BE OFF TO THE EAST WEDNESDAY NIGHT SO WENT
CHANCE POPS. WILL HAVE TO WATCH CLOSELY THOUGH IN CASE DEFORMATION
ZONE OR EVEN A TROWAL BRING BETTER CHANCES. WENT SNOW AS THE
PRECIPITATION TYPE WITH COLDER AIR QUICKLY MOVING IN. AT THE MOMENT
WILL KEEP ANY SNOWFALL AMOUNTS LESS THAN AN INCH.
FOR TEMPERATURES THROUGH THE PERIOD GENERALLY STUCK WITH A BLEND OF
GFS/ECMWF/MOS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
ISSUED AT 253 AM EST MON DEC 22 2014
STRONG SYSTEM SET TO IMPACT THE REGION CHRISTMAS EVE WILL LIFT INTO
QUEBEC BY EARLY CHRISTMAS MORNING...WILL ANY LEFTOVER LIGHT SNOW
SHOWERS DEPARTING AROUND OR SHORTLY BEFORE DAYBREAK. SURFACE RIDGING
WILL IMMEDIATELY EXPAND INTO THE OHIO VALLEY ON THURSDAY WITH CLOUDS
GRADUALLY DIMINISHING AS WINDS TURN SOUTHERLY. FOCUS SHIFTS ABRUPTLY
TO NEXT SURFACE WAVE EJECTING OUT OF THE CENTRAL PLAINS AS YET
ANOTHER SHARP UPPER TROUGH DIVES INTO THE NORTHERN ROCKIES. OVERALL
MODEL CONSENSUS IS NOT TOO BAD AT THIS POINT WITH RESPECT TO THE
SURFACE LOW TRACK INTO THE WESTERN GREAT LAKES BY FRIDAY NIGHT.
SOUTHERLY FLOW AND WARM ADVECTION AHEAD OF THIS FEATURE WILL BRING
MILDER AIR NORTH WITH ANY PRECIPITATION FALLING AS RAIN INTO FRIDAY
EVENING. COLDER AIR WILL SPILL IN LATE AS A COLD FRONT PASSES
THROUGH THE REGION...WITH PRECIP POSSIBLY MIXING WITH OR CHANGING TO
LIGHT SNOW INTO SATURDAY BEFORE ENDING.
REMAINDER OF THE EXTENDED QUITE A BIT MORE CONVOLUTED AS MODELS
EXHIBITING DIFFERENCES IN HANDLING OF SUBSEQUENT WAVES ALOFT
TRAVERSING THE LOWER 48. THE ECMWF AND GGEM STARTING TO FAVOR
SECONDARY SURFACE WAVE DEVELOPMENT ON THE TRAILING PART OF THE
AFOREMENTIONED COLD FRONT...BRINGING THE FEATURE NORTHEAST OUT OF
THE WESTERN GULF OF MEXICO UP INTO THE OHIO AND TENNESSEE VALLEYS BY
EARLY SUNDAY IN TANDEM WITH THE WAVE ALOFT. NOT SURPRISINGLY...OP
GFS/PARALLEL GFS AND PRETTY MUCH ALL OF THE GFS ENSEMBLE MEMBERS
PAINT A COMPLETELY DIFFERENT PICTURE...WITH ANY SECONDARY WAVE
DEVELOPMENT ON THE FRONT BEING SUPPRESSED ALONG THE GULF COAST WITH
NO UPPER SUPPORT PRESENT.
WILL MAINTAIN A DRY CHILLY FORECAST FOR THE SECOND HALF OF THE
WEEKEND TO MAINTAIN CONTINUITY FROM PREVIOUS FORECASTS...BUT IT WILL
BE INTERESTING TO SEE IF THE GLOBAL MODELS MAINTAIN THIS NEW IDEA OF
BRINGING A SECONDARY WAVE NORTH WITH POTENTIALLY ADDITIONAL
OPPORTUNITIES FOR WINTRY PRECIP SATURDAY NIGHT AND SUNDAY. NOT
ANTICIPATING ANY BETTER MODEL CONSENSUS FOR AT LEAST A FEW MORE
DAYS...ESPECIALLY CONSIDERING THE CHAOTIC MODEL PERFORMANCE
RECENTLY. DEFINITELY SOMETHING TO MONITOR GOING FORWARD.
&&
.AVIATION /DISCUSSION FOR 221200Z TAF ISSUANCE/...
ISSUED AT 922 AM EST MON DEC 22 2014
1423Z UPDATE...PUSHED BACK TIMING FOR MFVR BY AN HOUR FOR A FEW OF
THE SITES. OTHERWISE NO OTHER CHANGES NEEDED AT THIS TIME.
PREVIOUS DISCUSSION FOLLOWS.
DETERIORATING FLYING CONDITIONS THROUGH THE PERIOD WITH RAIN
IMPACTING THE TERMINALS THIS AFTERNOON INTO TONIGHT.
CLOUD DECK HAS QUICKLY ENCOMPASSED THE TERMINALS OVER THE LAST FEW
HOURS. MOISTURE WILL CONTINUE TO INCREASE AHEAD OF A WARM FRONT...
WITH CEILINGS EXPECTED TO SINK INTO MVFR CATEGORY BY MID MORNING.
LIGHT RAIN EXPANDING IN COVERAGE NEAR THE MISSISSIPPI RIVER AND
WILL CONTINUE NORTHEAST OVER THE NEXT FEW HOURS. HRRR KEEPS BULK
OF THE PRECIP THROUGH EARLY AFTERNOON WEST OF THE TERMINALS...WITH
ONLY KHUF AND POSSIBLY KLAF BEING IMPACTED.
AS LOW PRESSURE AND ITS ASSOCIATED WARM FRONT APPROACH THE REGION
LATER THIS AFTERNOON INTO THE EVENING HOWEVER...EXPECT WIDESPREAD
RAIN AND IFR CONDITIONS TO DEVELOP OVER CENTRAL INDIANA. SOUTHEAST
WINDS WILL STEADILY INCREASE TO 10-15KTS BY THIS EVENING...
EVENTUALLY VEERING TO A MORE SOUTHERLY DIRECTION AND BECOMING
GUSTY BY DAYBREAK TUESDAY AS THE WARM FRONT PASSES THROUGH THE
FORECAST AREA. RAIN WILL DECREASE IN COVERAGE AFTER 06Z AS THE
SURFACE LOW LIFTS INTO NORTHERN ILLINOIS...BUT LOW STRATUS WILL
PERSIST AS MODEL SOUNDINGS AND 925/950MB RH PROGS MAINTAIN DEEP
LOW LEVEL MOISTURE BENEATH AN INVERSION.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...50
NEAR TERM...50/JH
SHORT TERM...50
LONG TERM....RYAN
AVIATION...SMF/RYAN
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON FACEBOOK...TWITTER AND YOUTUBE AT:
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WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
925 AM EST MON DEC 22 2014
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 327 AM EST MON DEC 22 2014
AN UPPER TROUGH AND A COUPLE OF AREAS OF LOW PRESSURE WILL BRING
RAIN TO CENTRAL INDIANA TODAY INTO WEDNESDAY...WITH PERHAPS SOME
SNOW WEDNESDAY NIGHT. ANOTHER SYSTEM WILL BRING ADDITIONAL CHANCES
FOR PRECIPITATION FRIDAY AND SATURDAY. NEAR TO ABOVE AVERAGE
TEMPERATURES THIS WEEK WILL RETURN TO COOLER THAN AVERAGE FOR THE
WEEKEND.
&&
.NEAR TERM.../TODAY/
ISSUED AT 327 AM EST MON DEC 22 2014
ISENTROPIC LIFT WILL INCREASE TODAY AS AN UPPER TROUGH AND SURFACE
WARM FRONT MOVE TOWARD CENTRAL INDIANA. BEST FORCING ARRIVES LATE IN
THE DAY WHEN 850MB WINDS APPROACH 50KT AND AN UPPER JET MOVES CLOSER
TO THE AREA.
ANY PRECIPITATION WILL HAVE TO FIGHT THE DRY LOWER LEVELS OF THE
ATMOSPHERE INITIALLY. SOUTHEAST WINDS AT THE SURFACE WILL AID IN
KEEPING THE LOWER LEVELS DRY. THUS IT WILL TAKE THE ATMOSPHERE A
WHILE TO MOISTEN UP.
GIVEN THE ABOVE...WENT HIGHEST POPS TODAY AT THE END OF THE TODAY
PERIOD. GRADUALLY INCREASED POPS DURING THE DAY. BY LATE DAY WENT
LIKELY POPS FAR WEST...CHANCE CENTRAL...AND SLIGHT CHANCE FAR EAST.
CLOUDS WILL INCREASE/THICKEN THROUGH THE DAY. A BLEND OF MODELS
LOOKS BEST FOR HIGH TEMPERATURES...AND THIS ENDS UP NEAR TO A LITTLE
COOLER THAN MOS SUGGESTS.
&&
.SHORT TERM.../TONIGHT THROUGH WEDNESDAY NIGHT/
ISSUED AT 327 AM EST MON DEC 22 2014
FOCUS IS ON PRECIPITATION CHANCES THROUGH THE PERIOD. THREW OUT THE
NAM AS ITS SOLUTION OF BRINGING A SURFACE LOW NEAR THE APPALACHIANS
LOOKS UNREALISTIC. GFS/ECMWF/CANADIAN MODELS ARE SIMILAR AND LOOK
MORE REASONABLE...SO USED A BLEND OF THEIR SOLUTIONS.
RAIN WILL CONTINUE TO OVERSPREAD CENTRAL INDIANA TONIGHT WITH FIRST
A WARM FRONT THEN A COLD FRONT MOVING THROUGH THE AREA. 850MB JET
WILL PROVIDE GOOD MOISTURE AND FORCING...AND UPPER TROUGH/UPPER JET
WILL BRING ADDITIONAL FORCING. THUS WENT CATEGORICAL POPS ALL AREAS
TONIGHT. LOWERED POPS OVERNIGHT AS SOME DRIER AIR WORKS IN BEHIND
THE COLD FRONT.
MODELS NOW SHOWING A DRY SLOT ACROSS CENTRAL INDIANA FOR MUCH OF
TUESDAY. THIS SEEMS REASONABLE WITH FIRST SURFACE AND UPPER SYSTEMS
MOVING OFF THE NORTH...AND NEXT UPPER LOW AND SURFACE LOW STILL
ORGANIZING TO THE SOUTH/SOUTHWEST. HOWEVER DO NOT BELIEVE THE VERY
DRY GFS GIVEN THAT ANY WEAK UPPER IMPULSES COULD GENERATE SOME
SHOWERS.
THUS WENT MAINLY CHANCE POPS THROUGH THE DAY TUESDAY ACROSS THE
AREA. KEPT HIGHER POPS EAST DURING THE MORNING TO ACCOUNT FOR RAIN
ALONG THE EXITING SURFACE FRONT.
TUESDAY NIGHT POPS WILL INCREASE ONCE AGAIN AS THE NEXT SYSTEM
APPROACHES FROM THE SOUTH. BY 06Z WENT LIKELY POPS MOST AREAS.
ON WEDNESDAY A SURFACE LOW WILL MOVE THROUGH THE AREA. MODELS STILL
UNCERTAIN ON EXACT PATH...BUT IT SHOULD BE IN THE GENERAL AREA OF
CENTRAL INDIANA TO WESTERN OHIO. WENT HIGH END LIKELY POPS...AND MAY
NEED TO UP THEM TO CATEGORICAL AS WE GET CLOSER.
WITH THE MORE WESTERN TRACKS OF THE MODELS GAINING FAVOR /GFS
ENSEMBLE MEAN AND PARALLEL GFS ARE FARTHER WEST THAN OPERATIONAL GFS
AND ECMWF/ FEEL THAN RAIN WILL BE THE PRIMARY PRECIPITATION TYPE
THROUGH THE DAY WEDNESDAY. WENT WITH CHANCE OF SNOW MIXING IN ACROSS
ROUGHLY THE WEST HALF OF CENTRAL INDIANA IN THE LATE AFTERNOON AS
COLDER AIR STARTS TO WORK IN.
MOST OF THE FORCING WILL BE OFF TO THE EAST WEDNESDAY NIGHT SO WENT
CHANCE POPS. WILL HAVE TO WATCH CLOSELY THOUGH IN CASE DEFORMATION
ZONE OR EVEN A TROWAL BRING BETTER CHANCES. WENT SNOW AS THE
PRECIPITATION TYPE WITH COLDER AIR QUICKLY MOVING IN. AT THE MOMENT
WILL KEEP ANY SNOWFALL AMOUNTS LESS THAN AN INCH.
FOR TEMPERATURES THROUGH THE PERIOD GENERALLY STUCK WITH A BLEND OF
GFS/ECMWF/MOS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
ISSUED AT 253 AM EST MON DEC 22 2014
STRONG SYSTEM SET TO IMPACT THE REGION CHRISTMAS EVE WILL LIFT INTO
QUEBEC BY EARLY CHRISTMAS MORNING...WILL ANY LEFTOVER LIGHT SNOW
SHOWERS DEPARTING AROUND OR SHORTLY BEFORE DAYBREAK. SURFACE RIDGING
WILL IMMEDIATELY EXPAND INTO THE OHIO VALLEY ON THURSDAY WITH CLOUDS
GRADUALLY DIMINISHING AS WINDS TURN SOUTHERLY. FOCUS SHIFTS ABRUPTLY
TO NEXT SURFACE WAVE EJECTING OUT OF THE CENTRAL PLAINS AS YET
ANOTHER SHARP UPPER TROUGH DIVES INTO THE NORTHERN ROCKIES. OVERALL
MODEL CONSENSUS IS NOT TOO BAD AT THIS POINT WITH RESPECT TO THE
SURFACE LOW TRACK INTO THE WESTERN GREAT LAKES BY FRIDAY NIGHT.
SOUTHERLY FLOW AND WARM ADVECTION AHEAD OF THIS FEATURE WILL BRING
MILDER AIR NORTH WITH ANY PRECIPITATION FALLING AS RAIN INTO FRIDAY
EVENING. COLDER AIR WILL SPILL IN LATE AS A COLD FRONT PASSES
THROUGH THE REGION...WITH PRECIP POSSIBLY MIXING WITH OR CHANGING TO
LIGHT SNOW INTO SATURDAY BEFORE ENDING.
REMAINDER OF THE EXTENDED QUITE A BIT MORE CONVOLUTED AS MODELS
EXHIBITING DIFFERENCES IN HANDLING OF SUBSEQUENT WAVES ALOFT
TRAVERSING THE LOWER 48. THE ECMWF AND GGEM STARTING TO FAVOR
SECONDARY SURFACE WAVE DEVELOPMENT ON THE TRAILING PART OF THE
AFOREMENTIONED COLD FRONT...BRINGING THE FEATURE NORTHEAST OUT OF
THE WESTERN GULF OF MEXICO UP INTO THE OHIO AND TENNESSEE VALLEYS BY
EARLY SUNDAY IN TANDEM WITH THE WAVE ALOFT. NOT SURPRISINGLY...OP
GFS/PARALLEL GFS AND PRETTY MUCH ALL OF THE GFS ENSEMBLE MEMBERS
PAINT A COMPLETELY DIFFERENT PICTURE...WITH ANY SECONDARY WAVE
DEVELOPMENT ON THE FRONT BEING SUPPRESSED ALONG THE GULF COAST WITH
NO UPPER SUPPORT PRESENT.
WILL MAINTAIN A DRY CHILLY FORECAST FOR THE SECOND HALF OF THE
WEEKEND TO MAINTAIN CONTINUITY FROM PREVIOUS FORECASTS...BUT IT WILL
BE INTERESTING TO SEE IF THE GLOBAL MODELS MAINTAIN THIS NEW IDEA OF
BRINGING A SECONDARY WAVE NORTH WITH POTENTIALLY ADDITIONAL
OPPORTUNITIES FOR WINTRY PRECIP SATURDAY NIGHT AND SUNDAY. NOT
ANTICIPATING ANY BETTER MODEL CONSENSUS FOR AT LEAST A FEW MORE
DAYS...ESPECIALLY CONSIDERING THE CHAOTIC MODEL PERFORMANCE
RECENTLY. DEFINITELY SOMETHING TO MONITOR GOING FORWARD.
&&
.AVIATION /DISCUSSION FOR 221200Z TAF ISSUANCE/...
ISSUED AT 922 AM EST MON DEC 22 2014
1423Z UPDATE...PUSHED BACK TIMING FOR MFVR BY AN HOUR FOR A FEW OF
THE SITES. OTHERWISE NO OTHER CHANGES NEEDED AT THIS TIME.
PREVIOUS DISCUSSION FOLLOWS.
DETERIORATING FLYING CONDITIONS THROUGH THE PERIOD WITH RAIN
IMPACTING THE TERMINALS THIS AFTERNOON INTO TONIGHT.
CLOUD DECK HAS QUICKLY ENCOMPASSED THE TERMINALS OVER THE LAST FEW
HOURS. MOISTURE WILL CONTINUE TO INCREASE AHEAD OF A WARM FRONT...
WITH CEILINGS EXPECTED TO SINK INTO MVFR CATEGORY BY MID MORNING.
LIGHT RAIN EXPANDING IN COVERAGE NEAR THE MISSISSIPPI RIVER AND
WILL CONTINUE NORTHEAST OVER THE NEXT FEW HOURS. HRRR KEEPS BULK
OF THE PRECIP THROUGH EARLY AFTERNOON WEST OF THE TERMINALS...WITH
ONLY KHUF AND POSSIBLY KLAF BEING IMPACTED.
AS LOW PRESSURE AND ITS ASSOCIATED WARM FRONT APPROACH THE REGION
LATER THIS AFTERNOON INTO THE EVENING HOWEVER...EXPECT WIDESPREAD
RAIN AND IFR CONDITIONS TO DEVELOP OVER CENTRAL INDIANA. SOUTHEAST
WINDS WILL STEADILY INCREASE TO 10-15KTS BY THIS EVENING...
EVENTUALLY VEERING TO A MORE SOUTHERLY DIRECTION AND BECOMING
GUSTY BY DAYBREAK TUESDAY AS THE WARM FRONT PASSES THROUGH THE
FORECAST AREA. RAIN WILL DECREASE IN COVERAGE AFTER 06Z AS THE
SURFACE LOW LIFTS INTO NORTHERN ILLINOIS...BUT LOW STRATUS WILL
PERSIST AS MODEL SOUNDINGS AND 925/950MB RH PROGS MAINTAIN DEEP
LOW LEVEL MOISTURE BENEATH AN INVERSION.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...50
NEAR TERM...50
SHORT TERM...50
LONG TERM....RYAN
AVIATION...SMF/RYAN
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AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
543 AM EST MON DEC 22 2014
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 327 AM EST MON DEC 22 2014
AN UPPER TROUGH AND A COUPLE OF AREAS OF LOW PRESSURE WILL BRING
RAIN TO CENTRAL INDIANA TODAY INTO WEDNESDAY...WITH PERHAPS SOME
SNOW WEDNESDAY NIGHT. ANOTHER SYSTEM WILL BRING ADDITIONAL CHANCES
FOR PRECIPITATION FRIDAY AND SATURDAY. NEAR TO ABOVE AVERAGE
TEMPERATURES THIS WEEK WILL RETURN TO COOLER THAN AVERAGE FOR THE
WEEKEND.
&&
.NEAR TERM.../TODAY/
ISSUED AT 327 AM EST MON DEC 22 2014
ISENTROPIC LIFT WILL INCREASE TODAY AS AN UPPER TROUGH AND SURFACE
WARM FRONT MOVE TOWARD CENTRAL INDIANA. BEST FORCING ARRIVES LATE IN
THE DAY WHEN 850MB WINDS APPROACH 50KT AND AN UPPER JET MOVES CLOSER
TO THE AREA.
ANY PRECIPITATION WILL HAVE TO FIGHT THE DRY LOWER LEVELS OF THE
ATMOSPHERE INITIALLY. SOUTHEAST WINDS AT THE SURFACE WILL AID IN
KEEPING THE LOWER LEVELS DRY. THUS IT WILL TAKE THE ATMOSPHERE A
WHILE TO MOISTEN UP.
GIVEN THE ABOVE...WENT HIGHEST POPS TODAY AT THE END OF THE TODAY
PERIOD. GRADUALLY INCREASED POPS DURING THE DAY. BY LATE DAY WENT
LIKELY POPS FAR WEST...CHANCE CENTRAL...AND SLIGHT CHANCE FAR EAST.
CLOUDS WILL INCREASE/THICKEN THROUGH THE DAY. A BLEND OF MODELS
LOOKS BEST FOR HIGH TEMPERATURES...AND THIS ENDS UP NEAR TO A LITTLE
COOLER THAN MOS SUGGESTS.
&&
.SHORT TERM.../TONIGHT THROUGH WEDNESDAY NIGHT/
ISSUED AT 327 AM EST MON DEC 22 2014
FOCUS IS ON PRECIPITATION CHANCES THROUGH THE PERIOD. THREW OUT THE
NAM AS ITS SOLUTION OF BRINGING A SURFACE LOW NEAR THE APPALACHIANS
LOOKS UNREALISTIC. GFS/ECMWF/CANADIAN MODELS ARE SIMILAR AND LOOK
MORE REASONABLE...SO USED A BLEND OF THEIR SOLUTIONS.
RAIN WILL CONTINUE TO OVERSPREAD CENTRAL INDIANA TONIGHT WITH FIRST
A WARM FRONT THEN A COLD FRONT MOVING THROUGH THE AREA. 850MB JET
WILL PROVIDE GOOD MOISTURE AND FORCING...AND UPPER TROUGH/UPPER JET
WILL BRING ADDITIONAL FORCING. THUS WENT CATEGORICAL POPS ALL AREAS
TONIGHT. LOWERED POPS OVERNIGHT AS SOME DRIER AIR WORKS IN BEHIND
THE COLD FRONT.
MODELS NOW SHOWING A DRY SLOT ACROSS CENTRAL INDIANA FOR MUCH OF
TUESDAY. THIS SEEMS REASONABLE WITH FIRST SURFACE AND UPPER SYSTEMS
MOVING OFF THE NORTH...AND NEXT UPPER LOW AND SURFACE LOW STILL
ORGANIZING TO THE SOUTH/SOUTHWEST. HOWEVER DO NOT BELIEVE THE VERY
DRY GFS GIVEN THAT ANY WEAK UPPER IMPULSES COULD GENERATE SOME
SHOWERS.
THUS WENT MAINLY CHANCE POPS THROUGH THE DAY TUESDAY ACROSS THE
AREA. KEPT HIGHER POPS EAST DURING THE MORNING TO ACCOUNT FOR RAIN
ALONG THE EXITING SURFACE FRONT.
TUESDAY NIGHT POPS WILL INCREASE ONCE AGAIN AS THE NEXT SYSTEM
APPROACHES FROM THE SOUTH. BY 06Z WENT LIKELY POPS MOST AREAS.
ON WEDNESDAY A SURFACE LOW WILL MOVE THROUGH THE AREA. MODELS STILL
UNCERTAIN ON EXACT PATH...BUT IT SHOULD BE IN THE GENERAL AREA OF
CENTRAL INDIANA TO WESTERN OHIO. WENT HIGH END LIKELY POPS...AND MAY
NEED TO UP THEM TO CATEGORICAL AS WE GET CLOSER.
WITH THE MORE WESTERN TRACKS OF THE MODELS GAINING FAVOR /GFS
ENSEMBLE MEAN AND PARALLEL GFS ARE FARTHER WEST THAN OPERATIONAL GFS
AND ECMWF/ FEEL THAN RAIN WILL BE THE PRIMARY PRECIPITATION TYPE
THROUGH THE DAY WEDNESDAY. WENT WITH CHANCE OF SNOW MIXING IN ACROSS
ROUGHLY THE WEST HALF OF CENTRAL INDIANA IN THE LATE AFTERNOON AS
COLDER AIR STARTS TO WORK IN.
MOST OF THE FORCING WILL BE OFF TO THE EAST WEDNESDAY NIGHT SO WENT
CHANCE POPS. WILL HAVE TO WATCH CLOSELY THOUGH IN CASE DEFORMATION
ZONE OR EVEN A TROWAL BRING BETTER CHANCES. WENT SNOW AS THE
PRECIPITATION TYPE WITH COLDER AIR QUICKLY MOVING IN. AT THE MOMENT
WILL KEEP ANY SNOWFALL AMOUNTS LESS THAN AN INCH.
FOR TEMPERATURES THROUGH THE PERIOD GENERALLY STUCK WITH A BLEND OF
GFS/ECMWF/MOS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
ISSUED AT 253 AM EST MON DEC 22 2014
STRONG SYSTEM SET TO IMPACT THE REGION CHRISTMAS EVE WILL LIFT INTO
QUEBEC BY EARLY CHRISTMAS MORNING...WILL ANY LEFTOVER LIGHT SNOW
SHOWERS DEPARTING AROUND OR SHORTLY BEFORE DAYBREAK. SURFACE RIDGING
WILL IMMEDIATELY EXPAND INTO THE OHIO VALLEY ON THURSDAY WITH CLOUDS
GRADUALLY DIMINISHING AS WINDS TURN SOUTHERLY. FOCUS SHIFTS ABRUPTLY
TO NEXT SURFACE WAVE EJECTING OUT OF THE CENTRAL PLAINS AS YET
ANOTHER SHARP UPPER TROUGH DIVES INTO THE NORTHERN ROCKIES. OVERALL
MODEL CONSENSUS IS NOT TOO BAD AT THIS POINT WITH RESPECT TO THE
SURFACE LOW TRACK INTO THE WESTERN GREAT LAKES BY FRIDAY NIGHT.
SOUTHERLY FLOW AND WARM ADVECTION AHEAD OF THIS FEATURE WILL BRING
MILDER AIR NORTH WITH ANY PRECIPITATION FALLING AS RAIN INTO FRIDAY
EVENING. COLDER AIR WILL SPILL IN LATE AS A COLD FRONT PASSES
THROUGH THE REGION...WITH PRECIP POSSIBLY MIXING WITH OR CHANGING TO
LIGHT SNOW INTO SATURDAY BEFORE ENDING.
REMAINDER OF THE EXTENDED QUITE A BIT MORE CONVOLUTED AS MODELS
EXHIBITING DIFFERENCES IN HANDLING OF SUBSEQUENT WAVES ALOFT
TRAVERSING THE LOWER 48. THE ECMWF AND GGEM STARTING TO FAVOR
SECONDARY SURFACE WAVE DEVELOPMENT ON THE TRAILING PART OF THE
AFOREMENTIONED COLD FRONT...BRINGING THE FEATURE NORTHEAST OUT OF
THE WESTERN GULF OF MEXICO UP INTO THE OHIO AND TENNESSEE VALLEYS BY
EARLY SUNDAY IN TANDEM WITH THE WAVE ALOFT. NOT SURPRISINGLY...OP
GFS/PARALLEL GFS AND PRETTY MUCH ALL OF THE GFS ENSEMBLE MEMBERS
PAINT A COMPLETELY DIFFERENT PICTURE...WITH ANY SECONDARY WAVE
DEVELOPMENT ON THE FRONT BEING SUPPRESSED ALONG THE GULF COAST WITH
NO UPPER SUPPORT PRESENT.
WILL MAINTAIN A DRY CHILLY FORECAST FOR THE SECOND HALF OF THE
WEEKEND TO MAINTAIN CONTINUITY FROM PREVIOUS FORECASTS...BUT IT WILL
BE INTERESTING TO SEE IF THE GLOBAL MODELS MAINTAIN THIS NEW IDEA OF
BRINGING A SECONDARY WAVE NORTH WITH POTENTIALLY ADDITIONAL
OPPORTUNITIES FOR WINTRY PRECIP SATURDAY NIGHT AND SUNDAY. NOT
ANTICIPATING ANY BETTER MODEL CONSENSUS FOR AT LEAST A FEW MORE
DAYS...ESPECIALLY CONSIDERING THE CHAOTIC MODEL PERFORMANCE
RECENTLY. DEFINITELY SOMETHING TO MONITOR GOING FORWARD.
&&
.AVIATION /DISCUSSION FOR 221200Z TAF ISSUANCE/...
ISSUED AT 543 AM EST MON DEC 22 2014
DETERIORATING FLYING CONDITIONS THROUGH THE PERIOD WITH RAIN
IMPACTING THE TERMINALS THIS AFTERNOON INTO TONIGHT.
CLOUD DECK HAS QUICKLY ENCOMPASSED THE TERMINALS OVER THE LAST FEW
HOURS. MOISTURE WILL CONTINUE TO INCREASE AHEAD OF A WARM FRONT...
WITH CEILINGS EXPECTED TO SINK INTO MVFR CATEGORY BY MID MORNING.
LIGHT RAIN EXPANDING IN COVERAGE NEAR THE MISSISSIPPI RIVER AND
WILL CONTINUE NORTHEAST OVER THE NEXT FEW HOURS. HRRR KEEPS BULK
OF THE PRECIP THROUGH EARLY AFTERNOON WEST OF THE TERMINALS...WITH
ONLY KHUF AND POSSIBLY KLAF BEING IMPACTED.
AS LOW PRESSURE AND ITS ASSOCIATED WARM FRONT APPROACH THE REGION
LATER THIS AFTERNOON INTO THE EVENING HOWEVER...EXPECT WIDESPREAD
RAIN AND IFR CONDITIONS TO DEVELOP OVER CENTRAL INDIANA. SOUTHEAST
WINDS WILL STEADILY INCREASE TO 10-15KTS BY THIS EVENING...
EVENTUALLY VEERING TO A MORE SOUTHERLY DIRECTION AND BECOMING
GUSTY BY DAYBREAK TUESDAY AS THE WARM FRONT PASSES THROUGH THE
FORECAST AREA. RAIN WILL DECREASE IN COVERAGE AFTER 06Z AS THE
SURFACE LOW LIFTS INTO NORTHERN ILLINOIS...BUT LOW STRATUS WILL
PERSIST AS MODEL SOUNDINGS AND 925/950MB RH PROGS MAINTAIN DEEP
LOW LEVEL MOISTURE BENEATH AN INVERSION.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...50
NEAR TERM...50
SHORT TERM...50
LONG TERM....RYAN
AVIATION...RYAN
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AREA FORECAST DISCUSSION
NWS TOPEKA KS
512 AM CST Mon Dec 22 2014
...AVIATION UPDATE...
.SHORT TERM...(Today and Tonight)
Issued at 240 AM CST MON DEC 22 2014
Water vapor imagery continues to show a broad upper level trough
over the central U.S. at 09Z. Profiler and airplane reports show a
150+ KT jet streak on the back side of the upper trough from the
Pacific northwest into the central Rockies. Meanwhile at the
surface, an area of low pressure was forming over the northern
plains with a trough axis extending south through western and
central KS.
For today the surface trough axis/front is expected to gradually
move east across the area as energy on the back side of the upper
trough causes a closed upper level low to develop over the central
plains. As it does, models prog a decent shortwave to swing through
northern KS providing forcing for showers along the trough axis. All
of the models seem to be in agreement on this, and the only real
difference in the solutions is the GFS seems to be the deepest with
the upper low and the surface reflection. This may explain why the
GFS is a little more aggressive with the surface winds this
afternoon on account of having the strongest pressure gradient. In
any case, it looks like the strongest vertical motion from the
shortwave moves overhead during the late morning and early
afternoon. With this in mind, have the highest pops along and east
of the expected trough axis location through the early afternoon.
Considered inserting a mention of thunder to the forecast as the
shortwave rotates through the area. The NAM and GFS show a small
window where mid level lapse rates steepen to around 8 C/km. But
since instability remains very modest due to the cool and moist
nature of the airmass, have left the forecast all rain. However I
would not be surprised if there were a couple rumbles of thunder
early in the afternoon across east central KS. Cloud cover and
precip are expected to keep temps from warming much and have highs
in the mid 40s, or only several degrees warmer than current
readings.
Tonight should see surface winds become westerly as a surface low
propagates into the MS river valley. This should usher in some
relatively dry air to the forecast area. Unfortunately the closed
upper low is expected to remain over the MO river valley with the
potential for upper level deformation and moisture wrapping around
the back side of the upper low back into northern KS. The GFS seems
to be the more bullish solution with its QPF overnight and am a
little concerned this may be due to it developing a deeper system
then other solutions. Nevertheless have held onto POPs tonight
showing the potential for precip. Models show mostly subsidence
developing this evening across east central KS, so think any chance
for precip overnight will be across northern KS and along the NEB
boarder. There looks to be enough cold air moving in that the precip
could be in the form of snow after midnight as well. At this point
with temps forecast to be in the lower and mid 30s overnight and
models showing the better mid level frontogenesis setting up over
southeast NEB, think snow may only amount to a dusting before 12Z.
.LONG TERM...(Tuesday through Sunday)
Issued at 240 AM CST MON DEC 22 2014
A complicated forecast in the mid term as minor changes between
model runs create major changes in the location of optimal lift and
consequential precipitation, especially from Tuesday through
Wednesday morning. Nevertheless, it does appear model guidance in
showing better consistency with an upper jet streak within the
northwest flow diving southeast towards the southern plains. As this
occurs, embedded lift enhances behind the departing upper low.
Better confidence in this system lead to higher precip chances for
the CWA Tuesday as the wave and cold front move through. Still
remains some uncertainty in strength of this wave. Cross sections
and previous runs reveal the GFS to be an outlier with the amount of
forcing and generous amounts of QPF Tuesday afternoon. Leaned closer
to the ECMWF and NAM solutions as ensemble solutions shows similar
characteristics with the evolution. As precipitation develops along
and behind the boundary, temps will fall close to or just above the
freezing mark. A mix of rain and snow is possible, transitioning to
all snow by early evening, and gradually exiting east central KS
Wednesday morning. At this time do not see areas of strong,
persistent lift and instability to indicate banding precip. Snow
ratios averaged at 12:1 lend to total snowfall accumulations near or
less than an inch by Wednesday morning. Will continue to monitor
trends in the upcoming days as this system has the potential to
impact travel.
For Christmas Eve, southerly winds increase as a lee surface trough
builds, advecting warm air back into the CWA through Christmas Day.
Dry air advection slowly pushes east Wednesday afternoon, as north
central areas may break out into mostly sunny skies. Highs recover
into the upper 30s with overnight lows in the upper 20s. Southerly
winds increase Christmas Day as a slow moving upper trough enters
over the Rockies. Skies become mostly sunny for all of northeast
Kansas as increased WAA boosts highs in the upper 40s. Bulk of the
system and associated QPF passes to the north of the CWA Thursday
evening and Friday. Still could not rule out very light snow
impacting north central areas, otherwise no impacts are seen in
terms of precip. Another cold front cools highs back into the 30s
for the weekend as dry high pressure takes control of the region.
&&
.AVIATION...(For the 12Z TAFs through 12Z Tuesday Morning)
Issued at 511 AM CST MON DEC 22 2014
IFR CIGS are likely to persist until the surface trough axis
passes through the terminals and winds shift to the west. This
should bring in relatively dry air and an end to the light rain.
Once the trough axis passes, models show the boundary layer
moisture mixing out leading to a greater potential for VFR
conditions. There are some timing issues between the NAM and RAP
with when low clouds may mix out. For now leaned a little closer
to the quicker RAP since this lines up well with the FROPA and is
supported somewhat by the HRRR.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...Wolters
LONG TERM...Bowen
AVIATION...Wolters
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
724 AM EST MON DEC 22 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 425 AM EST MON DEC 22 2014
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SW FLOW ALOFT OVER
THE WRN GREAT LKS TO THE E OF A DEEPENING UPR TROF IN THE CENTRAL
CONUS CAUSED BY SHRTWVS DIGGING SEWD IN NW FLOW ALOFT E OF UPR RDG
ALONG THE W COAST. SHRTWV RESPONSIBLE FOR THE SN ON SUN EVNG IS
LIFTING NEWD THRU NW ONTARIO. AS THE ACCOMPANYING STRONGER DYNAMIC
FORCING SHIFTS TO THE NE...IR STLT IMAGERY SHOWS WARMING CLD TOP
TEMPS AS THE COMMA TAIL MSTR BAND SHIFTS TO THE E. ALTHOUGH RADAR
SHOWS THE HEAVIER PCPN IS FOLLOWING OFF TO THE NE...SOME PATCHY
ECHOES REMAIN OVER MUCH OF THE CWA. COMPOSITE RADAR INDICATES
GENERALLY LIGHT MIXED PCPN STRETCHES OFF TO THE SW THRU MUCH OF THE
NW HALF OF WI...WHERE MODELS SHOW AN AXIS OF WEAKER DEEP LYR QVECTOR
CNVGC. SFC OBS INDICATE LOWER SFC DEWPTS OVER NRN LOWER MI...UPWIND
OF THE E HALF OF THE CWA.
MAIN FCST CONCERNS TODAY FOCUS ON DIMINISHING PCPN TRENDS. FOCUS FOR
TNGT SHIFTS TO TIMING THE ARRIVAL OF ANOTHER AREA OF SN/MIXED PCPN
AS ANOTHER SHRTWV LIFTS NEWD OUT OF DEEPENING UPR TROF THAT CAUSES A
CLOSED H5 LO TO DEVELOP IN THE CENTRAL PLAINS.
TODAY...EXPECT SOME GENERALLY LGT SN/MIXED WITH RA TO IMPACT MAINLY
THE W HALF OF THE CWA THRU THIS MRNG AWAY FM THE DRIER NEAR SFC AIR
ADVECTING INTO THE ERN ZNS AND UNDER LINGERING BUT SLOWLY FADING
DEEP LYR QVECTOR CNVGC AS SHRTWV RDG APRCHS FM THE SW. DURING THE
AFTN...ARRIVAL OF DRIER AIR ALOFT FM THE S WITHIN THE NVA SHOULD END
ANY LINGERNING LARGE SCALE PCPN. BUT CONCERNED SOME SN GRAINS/
FREEZING DZ/DZ WL LINGER OVER MAINLY THE CENTRAL CWA WITH UPSLOPE SE
FLOW OFF LK MI. THIS POTENTIAL WL BE LIMITED BY ADVECTION OF LOWER
H95-9 SPECIFIC HUMIDITY NOW OVER NRN LOWER MI...ESPECIALLY OVER THE
E HALF AND BY LATE AFTN EVEN OVER THE CENTRAL. EXPECT TEMPS TO TOP
OUT ABOVE FREEZING EVERYWHERE...SO ANY FREEZING DZ SHOULD END BY
NOON OR SO.
TNGT...AS AREA OF SGNFT DEEP LYR QVECTOR CNVGC/DEEP ISENTROPIC
ASCENT/UPR DVGC IN ADVANCE OF SHRTWV LIFTING NE TOWARD THE GREAT LKS
OVERSPREADS THE AREA...EXPECT PCPN TO DEVELOP OVER THE SCENTRAL BY
MIDNGT AND THEN SPREAD TO OVER ALL THE KEWEENAW BY 12Z TUE. PER NCEP
PREFERENCE...TENDED TOWARD THE 00Z NAM FOR FCST DETAILS. THIS MODEL
GENERATES ABOUT 0.25 INCH OF TOTAL QPF AT MENOMINEE BY 12Z TUE.
PTYPE IS A CONCERN. WHILE THE NAM FCST SDNG FOR MENOMINEE INDICATES
MAINLY RA FOR THAT LOCATION...MODEL SDNGS/H100-85 THKNS INDICATE
AREAS AWAY FM LK MI WL SEE MAINLY SN THRU 12Z TUE. ARRIVAL OF LLVL
DRY AIR TODAY THAT WL ENHANCE NEAR SFC EVAPORATIVE COOLING AND
BACKING NEAR SFC FLOW TOWARD THE ENE THAT WL CUTOFF THE ARRIVAL OF
WARMER AIR APPEAR TO BE THE REASON THE LLVL TEMPS TREND COLD ENUF
FOR MAINLY SN EXCEPT NEAR LK MI. SN/WATER RATIOS WL BE LIMITED BY
RELATIVELY HI/THIN DGZ...SO AN INCH OR TWO OF SN WL LIKELY
ACCUMULATE BY SUNRISE OVER MUCH OF THE SE HALF OF THE CWA TO THE NW
OF THE RA/SN LINE.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 438 AM EST MON DEC 22 2014
...WIDESPREAD MODERATE SNOW ON TUESDAY...
ONE PRIMARY CHANCE FOR ACCUMULATING SNOW OVER ALL OF CWA IN THE LONG
TERM ON TUESDAY BUT CANNOT RULE OUT MORE SNOW CHIRSTMAS EVE FOR
EASTERN CWA AS THE ON AGAIN OFF AGAIN LOW PRESSURE SYSTEM IS STILL
AROUND IN LATEST MODELS. ANOTHER SYSTEM MAY IMPACT REGION WITH SWATH
OF SNOW FRIDAY INTO SATURDAY...BUT LACK OF CONTINUITY FM THE MODELS
LIMITS CONFIDENCE IN THAT PART OF FORECAST ATTM.
EVOLVING LOW PRESSURE SYSTEM MOVING OUT OF THE PLAINS TUESDAY INTO
WEDNESDAY APPEARS MORE LIKE RECENT RUNS OF ECMWF. QUESTION IS HOW
FAR EAST THE MID-LEVEL AND SFC LOWS REACH ON TUESDAY AS THAT IMPACTS
DRY SLOT AND PRECIP INTENSITY...ESPECIALLY OVER THE SOUTHERN PART OF
CWA. BLEND OF NAM/SREF SUPPORTED BY NCEP AND LOOKED LIKE 12Z ECMWF.
PRIMARY SHORTWAVE AND SFC LOW MOVE TO EASTERN IOWA BY 12Z TUESDAY
AND LIFT ACROSS EASTERN WISCONSIN ON TUESDAY AFTN. CIRCULATION AROUND
SFC-H85 LOWS PULLS H7 MIXING RATIOS OVER 3G/KG NORTH OF THE LOWS OVER
MAJORITY OF UPR MICHIGAN. PER GARCIA METHOD WITH NO PTYPE
CONSIDERATIONS THAT WOULD FAVOR 3 INCHES OF SNOW IN 6 HRS. BLEND OF
FAVORED QPFS POINT TO 0.30-0.50 INCH OF LIQUID EQUIVALENT OVER MOST
CWA...WITH HIGHER AMOUNTS OVER 0.50 INCH OVER FAR WEST AND SCNTRL.
TROUBLE IS 00Z ECMWF TRENDED EAST WITH SFC LOW AND HAS DRY SLOT INTO
SCNTRL...REALLY CUTTING ITS PRECIP THERE.
PTYPE ALSO AN ISSUE...UNFORTUNATELY. SOUNDINGS FM NAM KEEP BLYR
COOL...WITH ONLY SURE CHANGE TO RAIN AT MNM WITH ENE FLOW OFF BAY OF
GREEN BAY. ENE WINDS WOULD LEAD TO COOLING TO PERSIST AT KESC AND
KISQ. GFS SIMILAR WHILE GEM-REGIONAL IS MUCH WARMER/WESTWARD WITH
1000-850MB THICKNESSES OVER 1305M. SINCE WINDS ARE BACKING AND OFF
LAND IN LOW-LAYERS WILL FAVOR COOLER IDEA OFFERED BY NAM/GFS IN THE
MORNING BUT WILL BRING MORE GEM IDEA IN THE AFTN AS SFC LOW EDGES
CLOSER TO THE AREA FM THE SOUTH. RESULT WILL BE RAIN/SNOW MIX OVER
SCNTRL UPR MICHIGAN ALONG BAY OF GREEN BAY...WITH SNOW ELSEWHERE
INTO EARLY AFTN...THEN GO FOR A MIX OF RAIN AND SNOW OVER MOST OF
THE EAST HALF CWA BY MID AFTN. NAM SOUNDINGS SHOW THE SNOW MAY LAST
THROUGH THE DAY OVER MOST OF THE WEST HALF OF CWA AND EVEN FOLLOWING
GEM THICKNESSES QPF THAT OCCURS THERE IN THE MORNING WOULD STAY ALL
SNOW. OVERALL...WILL LEAN TOWARD MOST SNOW OVER WEST HALF. SOUNDINGS
MAINTAIN LOOK OF ELEVATED NARROW DGZ AND TEMPS WARMER THAN -8C
BLO...SO LOW SLR/S...PROBABLY AROUND 10:1. BY LATE TUESDAY
AFTN...EXPECT TOTAL SNOWFALL OVER 4 INCHES OVER MOST OF THE WEST
HALF OF THE CWA...MAYBE PUSHING TOWARD 6 INCHES OVER INTERIOR WEST.
CLOSER TO LK SUPERIOR OVR NCNTRL WHERE ENE WINDS PROVIDE FLOW OF
LAKE MODIFIED WARMING...EXPECT SNOW TOTALS TO BE HELD DOWN. CONTINUED
TO INCREASE POPS TO CATEGORICAL. IT WILL SNOW. ONLY THING THAT
TEMPERS CONFIDENCE ON ISSUING 3RD PERIOD ADVY IS INCONSISTENCIES IN
WHERE THE HIGHER QPF IS ON MODELS. WILL OPT FOR A SPECIAL WEATHER
STATEMENT AND LET DAYSHIFT GET SOME MORE DATA BEFORE MAKING FINAL
CALL ON HEADLINE.
BULK OF PRECIP WILL BE DONE BY WEDNESDAY EVENING. 00Z NAM WAS QUITE
EMPHATIC WITH DEFORMATION ZONE OF LINGERING SNOW OVER THE WEST CWA
BUT WAS NOT SUPPORTED IN ITS INTENSITY BY ANY OTHER GUIDANCE. 06Z
NAM IS NOT AS BULLISH. THOUGH SOME LGT SNOW COULD CONTINUE AS AN
AREA OF MID LEVEL FGEN/DEFORMATION WILL BE REINFORCED BY WEAK TROWAL.
EVEN THIS AREA OF SNOW SHOULD DIMINISH TO LGT SNOW/FLURRIES LATE ON
TUESDAY NIGHT. FARTHER EAST...SOUNDINGS SIGNAL POSSIBLE DRIZZLE OR
FREEZING DRIZZLE AND FOG AS MID-LEVEL DRYING LEAVES MOIST LOW-LEVELS
WITH TEMPS MAINLY WARMER THAN -7C. CARRIED SLIGHT CHANCE POPS FOR
RAIN/SNOW...BUT THIS MAY NEED TO BE CONVERTED TO DZ/FOG WITH LATER
FORECASTS.
MODELS CONTINUE TO HAVE FUN WITH THE CHRISTMAS EVE SYSTEM AFFECTING
THE GREAT LAKES. AFTER BACKING AWAY COMPLETELY 24 HR AGO...MOST OF
THE MODELS CAME BACK TO SHOWING A STRONG LOW LIFTING NORTHWARD OVER
THE CNTRL GREAT LAKES WITH THE RUNS ON SUNDAY. THAT IS WHERE WE
REMAIN FOR MOST PART NOW...WITH ALL BUT THE GEM-GLOBAL AND PARALLEL
GFS INDICATING THIS SYSTEM MISSES UPR MICHIGAN. KEPT SMALL CHANCES
IN OVER FAR EAST...VCNTY OF LUCE COUNTY...BUT OTHERWISE KEPT THE CWA
VOID OF ANY POPS FM THE SYSTEM. HAVE SOME SMALL CHANCE POPS OVER THE
WEST HALF ON CHRISTMAS EVE DAY...BUT THIS IS GENERALLY DUE TO SOME
SIMBLANCE OF THE LINGERING DEFORMATION AREA FM THE TUESDAY SYSTEM
THAT WILL ONLY BE SLOWLY UNRAVELING OVER THE EAST PART OF CWA ON
WEDNESDAY.
INTO CHRISTMAS AND BEYOND...RAN WITH CONSENSUS. COULD SEE SOME LGT
LK EFFECT FOR WNW-NW FLOW AREAS ON CHRISTMAS THOUGH H85 TEMPS NEAR
-10C ARE ONLY MARGINAL FOR PURE LES. WOULD NEED SOME ADDITIONAL
LARGE SCALE SUPPORT TO RESULT IN BETTER CHANCES OF LES VIA LAKE
ENHANCEMENT. AS LONG AS THE CNTRL GREAT LAKES LOW DOES NOT COME ANY
FARTHER WEST...WILL NOT BE VERY WINDY EITHER. HIGHS ON CHRISTMAS TOP
OUT ABOVE NORMAL...WITH LOW TO MID 30S EXPECTED. AS ALLUDED TO
EARLIER...ANOTHER CLIPPER TYPE SYSTEM COULD SPREAD SOME LGT SNOW TO
THE AREA ON FRIDAY. UNCERTAINTY AND CONSISTENCY IN THAT IDEA BOTH
ARE HIGH...SO CHANCE POPS UNTIL IT GETS MORE REFINED. AT THE MOST
COULD SEE MODERATE SNOW AMOUNTS. IDEA OF COLDER WEATHER WITH LK
EFFECT STILL ON TRACK FOR THE WEEKEND. MOISTURE IS A QUESTION THOUGH
SO EVEN THOUGH H85 TEMPS FALL DOWN BLO -15C ON SUNDAY...EVEN
MODERATE LK EFFECT SNOW IS NOT A DONE DEAL YET. COOLER TEMPS WILL BE
NOTICABLE THOUGH AFTER THE RATHER MILD CHRISTMAS WEEK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 716 AM EST MON DEC 22 2014
AS DEEPER MSTR EXITS TO THE N AND SOME LLVL DRY AIR MOVES IN FM THE
SSE TODAY...EXPECT IMPROVING CONDITIONS THRU THE DAY. BEST CHC FOR
SOME VFR WX WL BE AT IWD...WHERE THE LLVL SE WIND WL DOWNSLOPE. NOT
OUT OF THE QUESTION THAT CMX COULD SEE A PERIOD OF VFR CONDITIONS
LATE THIS AFTN AND EVNG AS WELL. BUT UPSLOPE NATURE OF THE EXPECTED
FLOW INTO SAW SHOULD LIMIT THE IMPROVEMENT THERE TO MVFR. THE APRCH
OF ANOTHER DISTURBANCE/LO PRES FM THE PLAINS WL BRING A RETURN OF
MORE SN LATE TNGT...EARLIEST AT SAW AND THEN OVERSPREADING THE REST
OF UPR MI LATE. SAW SHOULD SEE IFR CONDITIONS LATE WHILE CMX/IWD
FALL TO MVFR.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 425 AM EST MON DEC 22 2014
SSE WINDS UP TO 25-30 KTS OVER MAINLY THE E HALF OF LK SUPERIOR WILL
PERSIST THRU TODAY BUT THEN BACK TO THE E TONIGHT AND THEN THE NE ON
TUE AS A LO PRES SYSTEM MOVES NE FROM THE CENTRAL PLAINS TO OVER
LAKE MICHIGAN BY LATE IN THE DAY ON TUE. SINCE THIS LO WILL SLOWLY
WEAKEN AS IT MOVES TO THE NE...THE NE WINDS WILL FALL UNDER 20 KTS
ON TUE NIGHT. SINCE THE LATEST GUIDANCE INDICATES THE NEXT DEEPER LO
WILL TRACK N FARTHER TO THE E ON WED...A WEAKER PRES GRADIENT/N WIND
UNDER 20 KTS WILL DOMINATE ON WED. YET ANOTHER LO PRES MAY MOVE NE
FROM THE CENTRAL PLAINS LATE IN THE WEEK. AT THIS TIME...WINDS UNDER
25 KTS ARE EXPECTED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...JLA
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1005 AM CST MON DEC 22 2014
.UPDATE...
ISSUED AT 1005 AM CST MON DEC 22 2014
ANOTHER COMPLEX WEATHER SCENARIO ACROSS THE NORTHERN PLAINS THIS
MORNING.
DEFORMATION ZONE WELL ESTABLISHED ACROSS WESTERN NORTH DAKOTA
CONTRIBUTING TO ACCUMULATING SNOWFALL AS EXPECTED. REGIONAL
SATELLITE IMAGERY DEPICTS THE AXIS OF DILATATION WELL...STRETCHED
FROM WESTERN/CENTRAL SOUTH DAKOTA BACK NORTH-NORTHWEST ACROSS
WESTERN NORTH DAKOTA INTO SOUTHERN SASKATCHEWAN. CURRENT WINTER
WEATHER ADVISORY IN GOOD SHAPE THERE.
MODELS YESTERDAY ACCURATELY PREDICTED THE UNSATURATED ATMOSPHERE
NOW IN PLACE ACROSS THE NORTHEASTERN QUARTER OF THE STATE.
WIDESPREAD FREEZING DRIZZLE HAS BEEN ONGOING AND CONTINUES THERE.
MY COUNTIES BORDERING THE DEVILS LAKE BASIN ARE ON THE EDGE OF MID
LEVEL CLOUDS/SATURATE AIR ALOFT TO THE WEST. WE MADE A FEW CALLS TO
THOSE LOCATIONS AND BASED ON THOSE REPORTS AND IN COLLABORATION
WITH WFO GRAND FORKS OPTED TO HOIST A WINTER WEATHER ADVISORY FOR
THE FREEZING DRIZZLE. ENDED AT 00Z AS MODELS SUGGEST WE SHOULD BE
WELL SATURATED THROUGH THE MID LEVELS BY LATE THIS AFTERNOON.
DENSE FOG ADVISORY WAS EXTENDED THROUGH 19Z WITH VIS STILL 1/4
MILE OR LESS MANY LOCATIONS. WILL REEVALUATE OVER THE NEXT 3 HOURS
IN CASE IT NEEDS TO BE RE EXTENDED...OR PORTIONS OF IT.
NEXT WEATHER HAZARD WILL BE SNOW DEVELOPMENT ACROSS THE JAMES
RIVER VALLEY AND OVER MY FAR SOUTH CENTRAL AS A TROWAL BECOMES
ESTABLISHED AND WRAPS OVER THE EASTERN DAKOTAS. A WINTER WEATHER
ADVISORY MAY BE NEEDED THERE IN THE NEAR FUTURE AND WILL MAKE THAT
DECISION BEFORE 3PM CST TODAY.
UPDATE ISSUED AT 655 AM CST MON DEC 22 2014
WITH THIS UPDATE ISSUED A DENSE FOG ADVISORY THROUGH 16 UTC FOR
SOUTH CENTRAL NORTH DAKOTA AND THE JAMES RIVER VALLEY GIVEN
CURRENT OBSERVATIONS AND WEBCAMS. ALSO HIGHLIGHTED THE FREEZING
DRIZZLE POTENTIAL FOR THESE AREAS AS WELL. WILL ISSUE AN SPS FOR
THE NORTH CENTRAL WHERE FOG IS NOT DENSE...BUT...PATCHY FREEZING
DRIZZLE IS ALSO POSSIBLE. IN REGARDS TO THE WINTER WEATHER
ADVISORY...ADDED DIVIDE AND WILLIAMS COUNTIES AS THE 06 UTC
NAM/GFS...00 UTC GEM AND 10-11 UTC RAP RUNS ALL HIGHLIGHT THIS
AREA FOR THREE TO FOUR INCHES OF SNOW TODAY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 412 AM CST MON DEC 22 2014
FORECAST HIGHLIGHTS IN THE SHORT TERM WILL INCLUDE FOG AND THE
POSSIBILITY OF FREEZING DRIZZLE IN CENTRAL NORTH DAKOTA THIS
MORNING. THEN ATTENTION TURNS TO DEVELOPING SNOW IN THE WEST
SPREADING INTO CENTRAL NORTH DAKOTA...WITH ACCUMULATING SNOW AND
SOME BLOWING SNOW.
CURRENTLY...A SURFACE LOW WAS CENTERED OVER WESTERN NORTH DAKOTA -
OVER WESTERN LAKE SAKAKAWEA...WITH A TROUGH EXTENDING SOUTHEASTWARD
INTO CENTRAL SOUTH DAKOTA. LOW STRATUS CLOUDS BELOW 500 FEET AND FOG
WITH VISIBILITIES FROM 1/2 MILE TO 5 MILES. AT UPPER LEVELS A BROAD
TROUGH WAS IN PLACE ACROSS THE FRONT RANGE AND PLAINS STATES. WATER
VAPOR SAT LOOP INDICATES A SMALL CIRCULATION ACROSS SOUTHWESTERN
NORTH DAKOTA AND INTO WESTERN SOUTH DAKOTA...INDICATIVE OF EMBEDDED
SHORTWAVE AND A MINOR UPPER LOW. REGIONAL RADAR MOSAIC LOOPS
INDICATE INCREASING COVERAGE IN LIGHT RETURNS FROM NORTHEASTERN
MONTANA ACROSS WESTERN NORTH DAKOTA INTO CENTRAL/WESTERN SOUTH
DAKOTA. DICKINSON REPORTED "UNKNOWN PRECIPITATION" THIS PAST
HOUR...WHICH COULD BE RAIN CHANGING TO SNOW.
THE UPPER LEVEL LOW/TROUGH IS EXPECTED TO CONTINUE DEVELOPING A
CLOSED LOW OVER SOUTH DAKOTA THIS AFTERNOON. THIS WILL INDUCE THE
SURFACE LOW CENTER TO DEVELOP SOUTH INTO CENTRAL/EASTERN SOUTH
DAKOTA TODAY. THUS THE MAIN ENERGY...UPPER LEVEL CIRCULATION AND
LIFT...AND BEST SURFACE CONVERGENCE WILL DEVELOP SOUTH OF THE ND/SD
BORDER. SINCE THE EVOLUTION OF THIS SYSTEM HAS SLOWED AND EXPECTED
PRECIPITATION HAS BEEN LATER THAN PREVIOUSLY FORECAST...COMBINED
WITH THE SOUTHWARD MOVEMENT OF THE STORM SYSTEM...WE DO NOT EXPECT
QUITE AS MUCH SNOWFALL ACROSS WESTERN AND CENTRAL NORTH DAKOTA.
INSTEAD THE BULK OF THE SNOW IS EXPECTED IN SOUTH DAKOTA AND INTO
SOUTHERN MINNESOTA.
EXPECT DEVELOPING SNOW OVER WESTERN NORTH DAKOTA THIS
MORNING...SPREADING INTO CENTRAL NORTH DAKOTA LATER THIS
MORNING...AND CONTINUING MAINLY ACROSS THE SOUTHERN HALF OF NORTH
DAKOTA TONIGHT AND INTO TUESDAY.
TOTAL SNOWFALL EXPECTED TODAY THROUGH TUESDAY: NORTHERN NORTH DAKOTA
SNOWFALL TOTALS SHOULD RANGE FROM 1/2 INCH IN THE TURTLE MOUNTAINS
TO AROUND 2 INCHES AT WILLISTON. ACROSS SOUTHERN NORTH DAKOTA
SNOWFALL TOTALS OF 2 TO 2 1/2 INCHES ALONG AND SOUTH OF A LINE FROM
WATFORD CITY TO HARVEY AND CARRINGTON.
NORTHWEST WINDS OF 15 TO 30 MPH ARE EXPECTED OVER SOUTHWESTERN NORTH
DAKOTA TODAY AND TONIGHT. THIS WILL CREATE AREAS OF BLOWING AND
DRIFTING SNOW THAT WOULD IMPACT HOLIDAY TRAVEL. A WINTER WEATHER
ADVISORY HAD BEEN ISSUED FOR THIS AREA...IN EFFECT TODAY AND
TONIGHT. WILL KEEP THIS ADVISORY GOING BECAUSE OF THE BLOWING SNOW
HAZARD REDUCING VISIBILITIES...DESPITE THE LOWER SNOW AMOUNTS
EXPECTED. WILL ALSO KEEP A SPECIAL WEATHER STATEMENT RUNNING FOR THE
REST OF WESTERN AND CENTRAL NORTH DAKOTA TO HIGHLIGHT THE EXPECTED
SNOW FOR HOLIDAY TRAVEL.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 352 AM CST MON DEC 22 2014
DIMINISHING SNOW ON TUESDAY AND LIGHT SNOW CHRISTMAS DAY HIGHLIGHT
THE EXTENDED FORECAST.
TO BEGIN THE PERIOD...THE 00 UTC DETERMINISTIC AND ENSEMBLE SUITES
ARE IN AGREEMENT ON WRAP AROUND LIGHT SNOWFALL ENDING FROM WEST
TO EAST THROUGH TUESDAY ACROSS NORTH DAKOTA AS THE UPPER LEVEL LOW
SLOWLY FILLS AND PROPAGATES INTO THE GREAT LAKES. TRAVEL ON
WEDNESDAY ACROSS THE NORTHERN PLAINS LOOKS GOOD. HOWEVER...FOR
CHRISTMAS DAY THURSDAY THE MODELS BEGIN TO DIVERGE ON THEIR TIMING
AND EVOLUTION OF THE PACIFIC NORTHWEST WAVE AS IT PROPAGATES
ACROSS THE ROCKIES...WITH AN ASSOCIATED SNOW BAND IN ISENTROPIC
LIFT POSSIBLE ACROSS THE DAKOTAS. WHILE UNCERTAINTY
REMAINS...SOME TRAVEL IMPACTS ARE POSSIBLE FOR CHRISTMAS DAY
ACROSS WESTERN AND CENTRAL NORTH DAKOTA. THEREAFTER...TEMPERATURES
TREND BELOW NORMAL A AS ABROAD LONG WAVE TROUGH ENVELOPS THE CONUS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 1005 AM CST MON DEC 22 2014
HAZARDS TO AVIATION TODAY INVOLVE LOW IFR CONDITIONS WITH PATCHY
FREEZING DRIZZLE CENTRAL AND EAST THIS MORNING. MVFR/IFR CONDITIONS
IN SNOW AND BLOWING SNOW AT KISN-KDIK WITH GUSTS TO 30 KTS AND VSBYS
LESS THAN 1 MILE AT TIMES IN BLOWING SNOW. MVFR/IFR IN SNOW WEST
SPREADING EAST. WIDESPREAD IFR CONDITIONS WILL PERSIST INTO
TONIGHT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 1 PM CST /NOON MST/ THIS AFTERNOON FOR
NDZ034>037-042-045>048-050-051.
WINTER WEATHER ADVISORY UNTIL 6 AM CST /5 AM MST/ TUESDAY FOR
NDZ001-009-017-031>033-040-041-043-044.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR NDZ005-
013-023-025.
&&
$$
UPDATE...NH
SHORT TERM...JV
LONG TERM...AYD
AVIATION...AYD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
654 AM CST MON DEC 22 2014
.UPDATE...
ISSUED AT 655 AM CST MON DEC 22 2014
WITH THIS UPDATE ISSUED A DENSE FOG ADVISORY THROUGH 16 UTC FOR
SOUTH CENTRAL NORTH DAKOTA AND THE JAMES RIVER VALLEY GIVEN
CURRENT OBSERVATIONS AND WEBCAMS. ALSO HIGHLIGHTED THE FREEZING
DRIZZLE POTENTIAL FOR THESE AREAS AS WELL. WILL ISSUE AN SPS FOR
THE NORTH CENTRAL WHERE FOG IS NOT DENSE...BUT...PATCHY FREEZING
DRIZZLE IS ALSO POSSIBLE. IN REGARDS TO THE WINTER WEATHER
ADVISORY...ADDED DIVIDE AND WILLIAMS COUNTIES AS THE 06 UTC
NAM/GFS...00 UTC GEM AND 10-11 UTC RAP RUNS ALL HIGHLIGHT THIS
AREA FOR THREE TO FOUR INCHES OF SNOW TODAY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 412 AM CST MON DEC 22 2014
FORECAST HIGHLIGHTS IN THE SHORT TERM WILL INCLUDE FOG AND THE
POSSIBILITY OF FREEZING DRIZZLE IN CENTRAL NORTH DAKOTA THIS
MORNING. THEN ATTENTION TURNS TO DEVELOPING SNOW IN THE WEST
SPREADING INTO CENTRAL NORTH DAKOTA...WITH ACCUMULATING SNOW AND
SOME BLOWING SNOW.
CURRENTLY...A SURFACE LOW WAS CENTERED OVER WESTERN NORTH DAKOTA -
OVER WESTERN LAKE SAKAKAWEA...WITH A TROUGH EXTENDING SOUTHEASTWARD
INTO CENTRAL SOUTH DAKOTA. LOW STRATUS CLOUDS BELOW 500 FEET AND FOG
WITH VISIBILITIES FROM 1/2 MILE TO 5 MILES. AT UPPER LEVELS A BROAD
TROUGH WAS IN PLACE ACROSS THE FRONT RANGE AND PLAINS STATES. WATER
VAPOR SAT LOOP INDICATES A SMALL CIRCULATION ACROSS SOUTHWESTERN
NORTH DAKOTA AND INTO WESTERN SOUTH DAKOTA...INDICATIVE OF EMBEDDED
SHORTWAVE AND A MINOR UPPER LOW. REGIONAL RADAR MOSAIC LOOPS
INDICATE INCREASING COVERAGE IN LIGHT RETURNS FROM NORTHEASTERN
MONTANA ACROSS WESTERN NORTH DAKOTA INTO CENTRAL/WESTERN SOUTH
DAKOTA. DICKINSON REPORTED "UNKNOWN PRECIPITATION" THIS PAST
HOUR...WHICH COULD BE RAIN CHANGING TO SNOW.
THE UPPER LEVEL LOW/TROUGH IS EXPECTED TO CONTINUE DEVELOPING A
CLOSED LOW OVER SOUTH DAKOTA THIS AFTERNOON. THIS WILL INDUCE THE
SURFACE LOW CENTER TO DEVELOP SOUTH INTO CENTRAL/EASTERN SOUTH
DAKOTA TODAY. THUS THE MAIN ENERGY...UPPER LEVEL CIRCULATION AND
LIFT...AND BEST SURFACE CONVERGENCE WILL DEVELOP SOUTH OF THE ND/SD
BORDER. SINCE THE EVOLUTION OF THIS SYSTEM HAS SLOWED AND EXPECTED
PRECIPITATION HAS BEEN LATER THAN PREVIOUSLY FORECAST...COMBINED
WITH THE SOUTHWARD MOVEMENT OF THE STORM SYSTEM...WE DO NOT EXPECT
QUITE AS MUCH SNOWFALL ACROSS WESTERN AND CENTRAL NORTH DAKOTA.
INSTEAD THE BULK OF THE SNOW IS EXPECTED IN SOUTH DAKOTA AND INTO
SOUTHERN MINNESOTA.
EXPECT DEVELOPING SNOW OVER WESTERN NORTH DAKOTA THIS
MORNING...SPREADING INTO CENTRAL NORTH DAKOTA LATER THIS
MORNING...AND CONTINUING MAINLY ACROSS THE SOUTHERN HALF OF NORTH
DAKOTA TONIGHT AND INTO TUESDAY.
TOTAL SNOWFALL EXPECTED TODAY THROUGH TUESDAY: NORTHERN NORTH DAKOTA
SNOWFALL TOTALS SHOULD RANGE FROM 1/2 INCH IN THE TURTLE MOUNTAINS
TO AROUND 2 INCHES AT WILLISTON. ACROSS SOUTHERN NORTH DAKOTA
SNOWFALL TOTALS OF 2 TO 2 1/2 INCHES ALONG AND SOUTH OF A LINE FROM
WATFORD CITY TO HARVEY AND CARRINGTON.
NORTHWEST WINDS OF 15 TO 30 MPH ARE EXPECTED OVER SOUTHWESTERN NORTH
DAKOTA TODAY AND TONIGHT. THIS WILL CREATE AREAS OF BLOWING AND
DRIFTING SNOW THAT WOULD IMPACT HOLIDAY TRAVEL. A WINTER WEATHER
ADVISORY HAD BEEN ISSUED FOR THIS AREA...IN EFFECT TODAY AND
TONIGHT. WILL KEEP THIS ADVISORY GOING BECAUSE OF THE BLOWING SNOW
HAZARD REDUCING VISIBILITIES...DESPITE THE LOWER SNOW AMOUNTS
EXPECTED. WILL ALSO KEEP A SPECIAL WEATHER STATEMENT RUNNING FOR THE
REST OF WESTERN AND CENTRAL NORTH DAKOTA TO HIGHLIGHT THE EXPECTED
SNOW FOR HOLIDAY TRAVEL.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 352 AM CST MON DEC 22 2014
DIMINISHING SNOW ON TUESDAY AND LIGHT SNOW CHRISTMAS DAY HIGHLIGHT
THE EXTENDED FORECAST.
TO BEGIN THE PERIOD...THE 00 UTC DETERMINISTIC AND ENSEMBLE SUITES
ARE IN AGREEMENT ON WRAP AROUND LIGHT SNOWFALL ENDING FROM WEST
TO EAST THROUGH TUESDAY ACROSS NORTH DAKOTA AS THE UPPER LEVEL LOW
SLOWLY FILLS AND PROPAGATES INTO THE GREAT LAKES. TRAVEL ON
WEDNESDAY ACROSS THE NORTHERN PLAINS LOOKS GOOD. HOWEVER...FOR
CHRISTMAS DAY THURSDAY THE MODELS BEGIN TO DIVERGE ON THEIR TIMING
AND EVOLUTION OF THE PACIFIC NORTHWEST WAVE AS IT PROPAGATES
ACROSS THE ROCKIES...WITH AN ASSOCIATED SNOW BAND IN ISENTROPIC
LIFT POSSIBLE ACROSS THE DAKOTAS. WHILE UNCERTAINTY
REMAINS...SOME TRAVEL IMPACTS ARE POSSIBLE FOR CHRISTMAS DAY
ACROSS WESTERN AND CENTRAL NORTH DAKOTA. THEREAFTER...TEMPERATURES
TREND BELOW NORMAL A AS ABROAD LONG WAVE TROUGH ENVELOPS THE CONUS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 654 AM CST MON DEC 22 2014
HAZARDS TO AVIATION TODAY INVOLVE LOW IFR CONDITIONS WITH PATCHY
FREEZING DRIZZLE CENTRAL AND EAST THIS MORNING. MVFR/IFR CONDITIONS
IN SNOW AND BLOWING SNOW AT KDIK WITH GUSTS TO 35 KTS AND VSBYS LESS
THAN 1 MILE AT TIMES IN BLOWING SNOW. MVFR/IFR IN SNOW WEST
SPREADING EAST. WIDESPREAD IFR CONDITIONS WILL PERSIST INTO
TONIGHT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 10 AM CST /9 AM MST/ THIS MORNING FOR
NDZ034>037-042-045>048-050-051.
WINTER WEATHER ADVISORY UNTIL 6 AM CST /5 AM MST/ TUESDAY FOR
NDZ001-009-017-031>033-040-041-043-044.
&&
$$
UPDATE...AYD
SHORT TERM...JV
LONG TERM...AYD
AVIATION...AYD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1025 AM EST MON DEC 22 2014
.SYNOPSIS...
HIGH PRESSURE WILL RETREAT NORTHEAST INTO THE CANADIAN MARITIMES
EARLY THIS WEEK...AS A WEAK LOW PRESSURE SYSTEM LIFTS UP THE MID
ATLANTIC COAST. AN INTENSIFYING STORM SYSTEM WILL TRACK WEST OF
PENNSYLVANIA WEDNESDAY NIGHT...PUSHING A COLD FRONT THROUGH
THE STATE. ANOTHER LESS POTENT COLD FRONT IS LIKELY TO IMPACT THE
REGION BY NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
15Z UPDATE** LOW CLOUDS LIFTING CENTRAL MOUNTAINS AT MID
MORNING WITH DEEPER MOISTURE STARTING TO POOL SOUTH OF THE MASON
DIXON LINE...IN RESPONSE TO INCREASING MARITIME INFLUENCE IN
INCREASING EASTERLY/ONSHORE FLOW BETWEEN CAPE HATTERAS LOW
PRESSURE AND NORTHERN NEW ENGLANHIGH PRESSURE. THE INCREASING
MOISTURE...COMBINED WITH LG SCALE FORCING AHEAD OF SHORTWAVE
LIFTING OUT THE SE STATES...COULD SPREAD A BIT OF LIGHT RAIN INTO
SOUTHERN PA THIS AFTN. BLEND OF LATEST MDL GUIDANCE SUPPORTS CHC
POPS ACROSS THE SOUTHERN COUNTIES THIS AFTN.
FOR THE DAY...THE MAIN CONCERN FOCUSES ON POTENTIAL OF SOME ICING
LATER ON... GIVEN COLD AIR DAMMING AND LLVL AGEOSTROPHIC NLY FLOW
LOCKING THE COLD AIR IN. LATEST HRRR AND 4KM HRW-ARW DIFFER
SIGNIFICANTLY ON ARRIVAL OF PRECIP INTO SOUTH CENTRAL PA. LATEST
HRW-ARW HAS COME INTO LINE WITH PREVIOUS HRRR HOWEVER...IN
DELAYING PRECIP UNTIL AFTER 20Z...AND MOST OF THAT BEING RAIN
OVERF THE LOWER SUSQ RIVER VALLEY.
THUS...LATEST HI RES RUNS...FORECAST SOUNDINGS AND ENS PTYPES
SUGGEST THE BEST ICING CHANCE LATE THIS AFTERNOON...STARTING NEAR
THE MASON DIXON LINE MID TO LATE AFTERNOON...AND LIFTING NORTHWARD
INTO THE LAURELS AND SOUTH CENTRAL MOUNTAINS BEFORE DARK.
STILL NO ADVY TO BE POSTED AT THIS TIME DUE TO THE LOW CERTAINTY
OF MEASURABLE FZRA...BUT CONFIDENCE INCREASING FROM ADAMS COUNTY
WESTWARD THAT AN ADVISORY MAY BE NEEDED FROM ADAMS COUNTY WESTWARD
MID TO LATE AFTERNOON. WILL MONITOR TRENDS AND ISSUE ACCORDINGLY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
MOIST SERLY FLOW OFF THE ATLANTIC AND ASSOC OROGRAPHIC FORCING OF
SHALLOW MOISTURE LYR WILL LIKELY PRODUCE PATCHY LGT RAIN/DRIZZLE
TONIGHT AND TUESDAY. BEST CHC OF MEASURABLE PRECIP SHOULD COME
BTWN 00Z-06Z THIS EVENING WITH BENEFIT OF LG SCALE FORCING AHEAD
OF MID LVL SHORTWAVE. SFC TEMP FIELDS OF BOTH OPER AND ENSEMBLE
DATA SUGGEST THERE COULD BE ICING CONCERNS OVER THE HIGHER TERRAIN
OF CENTRAL PA. HOWEVER...TEMPS WILL BE VERY MARGINAL WITH ICING
MOST LIKELY ON THE RIDGETOPS. ALSO...NOT ENTIRELY SURE MEASURABLE
PRECIP WILL EVEN REACH FAR ENOUGH WEST TO CREATE A CONCERN. WILL
THEREFORE CONTINUE TO MENTION THREAT OF ICY ROADS IN THE HWO AND
AWAIT 12Z GUIDANCE TO GET A BETTER HANDLE ON THIS EVENT.
ANY ICING THREAT SHOULD END BY DAYLIGHT TUESDAY...WHEN ALL PLUME
MEMBERS RISE ABV FREEZING. RAINFALL AMTS TUESDAY SHOULD BE VERY
LIGHT...WITH SHALLOW MOISTURE IN MDL SOUNDINGS IMPLYING OCNL
DRIZZLE RATHER THAN RAIN.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
THE MOST SIGNIFICANT FORECAST ISSUE IN THE LONG TERM REMAINS THE
EVOLUTION OF DEEP TROUGH AND ASSOC SFC LOW TRACKING WEST OF PA
WED/WED NITE. STRONG SOUTHERLY FLOW AHEAD OF THIS SYSTEM SHOULD SCOUR
OUT LINGERING SHALLOW COLD AIR EAST OF THE APPALACHIANS. LOW-LEVEL
TEMPERATURE AND MOISTURE FIELDS RISE WELL ABOVE THEIR SEASONAL
VALUES...IMPLYING IT WILL BE A BALMY CHRISTMAS EVE FOR ALL.
ALL MED RANGE GUIDANCE TIMES THE TRAILING COLD FRONT THRU CENTRAL
PA WED NITE. A STRONG SOUTHERLY LL JET AND ASSOC PWAT ANOMALIES
ABOUT +3 SIGMA ABOVE NORMAL ARE PROGGED BY GEFS TO PASS THRU THE
AREA IN ADVANCE OF THE FRONT WED NITE. THIS STRONG SOUTHERLY
FLOW...HIGH PRECIPITABLE WATER AND SHARP CDFRONT ALL IMPLY A
FRONTAL RAIN EVENT WITH PERHAPS SOME RARE LATE DECEMBER (ELEVATED)
CONVECTION. HAVE ADDED CHC OF THUNDER BASED ON EXPECTED STRONG LG
SCALE FORCING IN ADVANCE OF UPPER TROF AND PRESENCE OF SOME MEAGER
MDL CAPES.
INTENSIFYING SFC LOW PASSING NORTH OF PA IS A FAVORABLE PATTERN
FOR STRONG WINDS ACROSS CENTRAL PA DURING THE COLD SEASON...SO STILL
MONITORING THE POTENTIAL OF STRONG WINDS COINCIDENT AND FOLLOWING
PASSAGE OF CDFRONT LATE WED NITE AND THURSDAY. WILL MENTION
POTENTIAL IN HWO.
COLDER AIR WORKING IN BEHIND COLD FRONT WILL LIKELY PRODUCE
OROGRAPHIC SNOW SHOWERS ACROSS THE ALLEGHENY PLATEAU ON CHRISTMAS
DAY. HOWEVER...AIR MASS NOT LOOKING PARTICULARLY COLD AND SFC
TEMPS LIKELY TO BE ABV FREEZING...LIMITING THE POTENTIAL OF
ACCUMS.
TEMPERATURES SHOULD REBOUND FRIDAY AHEAD OF ANOTHER NORTHERN STREAM
WAVE MOVING INTO THE MID-WEST. ECENS OUTPUT SUGGESTS THIS
SHORTWAVE WILL LIFT NORTH OF PA NEXT WEEKEND...PUSHING A DYING COLD
FRONT INTO THE REGION.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
COMBINATION OF RETREATING HIGH PRES OVR THE CANADIAN MARITIMES AND
WEAK LOW LIFTING UP THE MID ATLANTIC COAST WILL SPREAD AN
INCREASINGLY MOIST SERLY FLOW INTO CENTRAL PA ON TODAY. LOWER CIGS
LIFTING NORTHWARD THIS MORNING IN RESPONSE TO DEEPENING LLVL
MOISTURE AND ONSHORE FLOW. THE INCREASING MOISTURE...COMBINED
WITH LG SCALE FORCING AHEAD OF SHORTWAVE LIFTING OUT THE SE
STATES...COULD SPREAD A BIT OF LIGHT RAIN INTO SOUTHERN PA LATE
THIS AFTN.
MAIN CONCERN WILL BE POTENTIAL OF SOME LIGHT ICING...GIVEN COLD
AIR DAMMING SIGNATURE AND IMPLIED LOW-LEVEL AGEOSTROPHIC NORTHERLY
FLOW HOLDING LOW-LEVEL COLD AIR IN. OPER MDL SOUNDINGS AND ENS
PTYPES SUGGEST THE BEST CHC OF LATE DAY LIGHT -FZRA WOULD BE OVR
THE LAUREL HIGHLANDS AND HIGHER TERRAIN OF THE SC MTNS...WITH A
BETTER CHANCE TONIGHT ACROSS THE CENTRAL MTNS.
OUTLOOK...
TUE...LOW CIGS WITH DRIZZLE/LIGHT RAIN LIKELY. BECOMING BREEZY
MAINLY ACROSS HIGHER TERRAIN. LLWS POSS N/W.
WED...PERIODS OF RAIN ALONG WITH WIDESPREAD REDUCTIONS. BREEZY.
LLWS LIKELY.
THU...WINDY AND COLDER WITH SCT MVFR CIGS AND -SHSN. LLWS.
FRI...FAIR AND MOSTLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD
NEAR TERM...DEVOIR/FITZGERALD
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD
AVIATION...RXR
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
114 PM EST MON DEC 22 2014
.SYNOPSIS...
UNSETTLED WEATHER IS EXPECTED THROUGH TUESDAY NIGHT AS SEVERAL
DISTURBANCES MOVE OVER THE REGION. A STRONG COLD FRONT WILL THEN
MOVE THROUGH THE AREA WEDNESDAY EVENING. DRY HIGH PRESSURE WILL
SETTLE OVER THE SOUTHEAST INTO THE WEEKEND. ANOTHER COLD FRONT
COULD SHIFT THROUGH THE AREA EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
A MUCKY PATTERN WILL CONTINUE FOR YET ANOTHER DAY AS A STRONG
WEDGE OF HIGH PRESSURE REMAINS OVER THE MID-ATLANTIC REGION AND
EXTENDS DOWN THE EASTERN SEABOARD AS FAR SOUTH AS SOUTHERN GA. A
DEEP UPPER LEVEL TROUGH OVER THE CENTRAL UNITED STATES CONTINUES
TO PROVIDE A STEADY FEED OF SHORTWAVE ENERGY ACROSS THE SOUTHEAST
STATES. INITIALLY IT SEEMED AS THOUGH THE JET DIVERGENCE WAS GOING
TO WEAKEN TODAY AND THE STRONGEST SHORTWAVE ENERGY WOULD SHIFT
NORTHEAST OF THE REGION. HOWEVER WE HAVE NOTED A FAIRLY WIDESPREAD
AREA OF RAIN MOVING OUT OF CENTRAL GA INTO OUR FORECAST AREA THIS
MORNING. THIS IS ASSOCIATED WITH A WEAK SLUG OF ISENTROPIC OMEGA
THAT THE 12Z NAM FINALLY PICKED UP ON. THE LATEST HRRR HAS ALSO
CAUGHT ONTO THE INLAND PRECIP WHICH SHOULD PROGRESS NORTHEAST
THROUGH THE AREA THIS AFTERNOON. SIGNIFICANT CHANGES TO THE POP
GRIDS WERE IN ORDER THIS MORNING. WE ARE NOW CARRYING LIKELY OR
CATEGORICAL POPS OVER MANY LAND AREAS THROUGH EARLY AFTERNOON...
GRADUALLY TAPERING BACK LATE THIS AFTERNOON ONCE THE BEST FORCING
MOVES AWAY TO THE NORTHEAST. DENSE OVERCAST AND STEADY RAIN WILL
KEEP TEMPERATURES FAIRLY STEADY IN THE UPPER 40S TO LOWER 50S.
SOUNDINGS SHOW LOW-MID 50S AIR AT THE SURFACE TODAY AND THIS
EVENING AND MID 60S AIR AT 300-400 FT WHICH IS PRIME FOR STRATUS
BUILDING DOWN GIVEN A SETUP WITH LIGHTER WINDS IN THE BOUNDARY
LAYER. THE STORY TONIGHT SHOULD BE FOG...PROBABLY DENSE IN MANY
AREAS. WE HAVE ADDED DENSE FOG POTENTIAL TO THE HAZARDOUS WEATHER
OUTLOOK. OTHERWISE...THE WARM FRONT MAY MOVE INTO THE OUR SOUTHERN
GEORGIA ZONES BY DAYBREAK ON TUE AND A CONTINUATION OF PERIODIC
DRIZZLE AND MAINLY LIGHT RAIN SHOWERS. MID LEVELS LOOK PRETTY
UNSTABLE BUT ELEVATED THUNDER RISK IS PRETTY LOW AS MODELS SHOW
MID LEVEL NVA AND SOMEWHAT DRIER AIR ALOFT. TEMPS OVERNIGHT SHOULD
BE STEADY AND EVEN RISE LATE. POPS MAINLY IN THE CHANCE RANGE.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
TUESDAY AND WEDNESDAY...A LARGE SYNOPTIC SCALE TROUGH OF LOW PRESSURE
WILL DIG OVER THE CENTRAL UNITED STATES...SPAWNING A SFC LOW OVER
THE NORTHERN GULF OF MEXICO TUESDAY THAT QUICKLY DEEPENS AND LIFTS
NORTH/NORTHEAST WITH A COLD FRONT EXTENDING SOUTHWARD INTO WEDNESDAY.
A STRONG H5 SHORTWAVE ROUNDING THE BASE OF THE HIGH AMPLITUDE TROUGH
AS WELL AS A STRONG LOW/MID/UPPER LVL JET WILL LIKELY FORCE THE
SOUTHWARD EXTENDING COLD FRONT TO THE EAST...EVENTUALLY PUSHING IT
THROUGH THE FORECAST AREA LATE WEDNESDAY AFTERNOON INTO EARLY
WEDNESDAY NIGHT.
AHEAD OF THE COLD FRONT...A DEEP PLUME OF MOISTURE CHARACTERIZED BY
PWATS UP TO 1.8-1.9 INCHES WILL ADVECT TO THE AREA AS A WARM FRONT
BEGINS TO LIFT NORTH AND ENCOUNTERS THE PERSISTENT WEDGE INLAND.
WIDESPREAD SHOWERS WILL THEREFORE REMAIN IN THE FORECAST FOR MOST
AREAS. MODELS NOW SUGGEST THE WARM FRONT WILL LIFT A BIT FURTHER
NORTH ON TUESDAY THAN PREVIOUSLY NOTED...TRYING TO SCOUR OUT WHAT IS
LEFT OF WEDGE OF HIGH PRESSURE INLAND. HOWEVER...WE STILL BELIEVE
THIS IS A BIT AGGRESSIVE WITH THE WEDGE CURRENTLY IN PLACE SO HAVE
MAINTAINED TEMPS A FEW DEGREES BELOW GUIDANCE...ESPECIALLY INLAND
WHERE THE WEDGE SHOULD HOLD DURING PEAK HEATING HOURS TUESDAY
AFTERNOON. GIVEN THIS SCENARIO...SLIGHT CHANCES OF THUNDERSTORMS
WILL REMAIN IN THE FORECAST TUESDAY AFTERNOON/EVENING WHERE SBCAPES
APPROACH 800 J/KG AND MODEST MID LVL LAPSE RATES OCCUR SOUTH OF THE
WARM FRONT. WE COULD SEE SOME ENHANCEMENT TO THUNDERSTORM ACTIVITY
AS SEVERAL MID LVL WAVES OF ENERGY ADVANCE OVER THE AREA TUESDAY
AFTERNOON AND/OR EVENING. THUNDERSTORMS MAY ALSO NEED TO BE INCLUDED
IN FUTURE FORECASTS FOR INLAND AREAS SHOULD ELEVATED INSTABILITY
CONTINUE TO INCREASE OVER THE WEDGE. IN GENERAL...AFTERNOON HIGH
TEMPS SHOULD RANGE IN THE LOW/MID 60S INLAND TO UPPER 60S IN
SOUTHEAST GEORGIA TUESDAY AFTERNOON.
AS DIURNAL HEATING IS LOST TUESDAY NIGHT...THUNDERSTORM CHANCES
SHOULD MAINLY OCCUR OFFSHORE...BUT DEEP MOISTURE WILL LIKELY
MAINTAIN WIDESPREAD SHOWERS WHILE FORCING INCREASES FROM THE
WEST. TUESDAY NIGHT TEMPS WILL BE MILD WITHIN A SOUTHERLY FLOW AHEAD
OF THE APPROACHING COLD FRONT...WITH LOWS ONLY DIPPING INTO THE
UPPER 50S TO LOWER 60S.
WIDESPREAD CLOUD COVER AND ONGOING SHOWERS SHOULD LIMIT THE OVERALL
THERMODYNAMIC ENVIRONMENT ON WEDNESDAY. HOWEVER...STRONG WIND FIELDS
JUST OFF THE SFC COULD RESULT IN SOME GUSTY WINDS CONDITIONS AS
TEMPS APPROACH 70 DEGREES WEDNESDAY AFTERNOON. A SLIGHT CHANCE OF
THUNDERSTORMS WILL REMAIN IN THE FORECAST FOR ALL AREAS GIVEN THE
AMOUNT OF MID/UPPER LVL FORCING SHIFTING OVER THE REGION. HOWEVER
THE BEST CHANCES OF THUNDERSTORMS SHOULD OCCUR AS THE COLD FRONT
PUSHES INTO THE AREA WEDNESDAY EVENING INTO EARLY WEDNESDAY NIGHT.
GUSTY WINDS SHOULD CONTINUE FOR A FEW HOURS WEDNESDAY NIGHT AS
STRONG COLD AIR ADVECTION OCCURS BEHIND THE FRONT. CONDITIONS WILL
THEN QUICKLY DRY OUT FROM WEST TO EAST LATE WEDNESDAY NIGHT AS HIGH
PRESSURE BEGINS TO PUSH INTO THE REGION.
THURSDAY...MUCH DRYER/QUIET WEATHER CONDITIONS ARE EXPECTED AS THE
MID LVL TROUGH AXIS SHIFTS OFFSHORE AND HIGH PRESSURE SETTLES OVER
THE SOUTHEASTERN UNITED STATES. DESPITE A RETURN TO MOSTLY SUNNY
SKIES...TEMPS WILL REMAIN COOLER AS COLD AIR ADVECTS OVER THE AREA.
IN GENERAL...AFTERNOON TEMPS SHOULD RANGE IN THE MID TO UPPER 50S
OVER MOST AREAS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
QUIET WEATHER WILL PREVAIL INTO THE WEEKEND AS HIGH PRESSURE BECOMES
CENTERED OVER THE SOUTHEASTERN UNITED STATES. OVERALL HIGH TEMPS
SHOULD GRADUALLY WARM EACH DAY AS HIGH PRESSURE CONTINUES TO SLIDE
EAST LATE WEEKEND...ALLOWING A LIGHT SOUTHERLY FLOW TO RETURN TO THE
AREA. IN GENERAL...TEMPS WILL REACH THE LOWER 60S ON FRIDAY...THEN
TO THE MID 60S ON SATURDAY. OVERNIGHT LOWS SHOULD RANGE IN THE THE
LOW/MID 40S INTO THE WEEKEND. THE NEXT BEST CHANCE OF PRECIP SHOULD
OCCUR EARLY NEXT WEEK WITH A COLD FRONT THAT APPROACHES THE REGION.
HOWEVER...CONFIDENCE IN TIMING AND STRENGTH OF PATTERN IS QUITE LOW
GIVEN LARGE DISCREPANCIES IN MODEL SOLUTIONS.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
WE EXPECT BOTH TERMINALS TO REMAIN TANKED AT IFR OR LOWER THROUGH
THE MAJORITY OF THE 18Z TAF PERIOD. WIDESPREAD MODERATE TO HEAVY
RAIN WILL SPREAD ACROSS BOTH TERMINALS THIS AFTERNOON WITH
OCCASIONAL VSBY REDUCTIONS. A STRONG WEDGE OF HIGH PRESSURE WILL
REMAIN IN PLACE AT LEAST THROUGH TONIGHT. HOWEVER A WARM FRONT IS
EXPECTED TO LIFT NORTH LATE TONIGHT WITH INCREASING LOW- LEVEL
MOISTURE APPROACHING THE TERMINALS. ONGOING LIFR STRATUS WILL
LIKELY BUILD-DOWN THIS EVENING WITH VSBYS DROPPING TO LIFR.
CONDITIONS DO NOT SUPPORT MUCH RECOVERY ON TUESDAY...THOUGH SFC
VSBYS SHOULD IMPROVE A FEW HRS AFTER DAYBREAK. IFR OR LOWER
CEILINGS LIKELY TO PERSIST THROUGH MUCH OF THE DAY TUESDAY.
EXTENDED AVIATION OUTLOOK...PERIODS OF MVFR OR LOWER CONDITIONS ARE
LIKELY LIKELY TUESDAY AFTERNOON INTO WEDNESDAY AFTERNOON AS A STRONG
COLD FRONT APPROACHES FROM THE WEST WITH SHOWERS AND THUNDERSTORMS.
LLWS WILL BE A POSSIBILITY TUESDAY NIGHT AS STRONGER WIND FIELDS
SHIFT OVER THE AREA IN ADVANCE OF THE FRONT. MVFR OR LOWER
CONDITIONS AND GUSTY WINDS ARE EXPECTED UNTIL THE TIME OF FRONTAL
PASSAGE SOMETIME WEDNESDAY EVENING INTO EARLY WEDNESDAY NIGHT. VFR
CONDITIONS SHOULD THEN PREVAIL BY DAYBREAK THURSDAY.
&&
.MARINE...
MARINE CONDITIONS ARE SLOWLY IMPROVING THIS MORNING. THE GRADIENT
HAS WEAKENED ENOUGH TO ALLOW THE SMALL CRAFT ADVISORIES TO DROP
OFF AROUND DAYBREAK. THE DENSE FOG IN CHARLESTON HARBOR AND
IMMEDIATE CHARLESTON COASTAL WATERS HAS LIFTED TO A LOW STRATUS
DECK. CHS PILOT OFFICE REPORTS VSBYS AROUND 3 NM AS OF 9 AM WITH
THE PORT REOPENED TO COMMERCIAL SHIPPING TRAFFIC. WE DROPPED THE
DENSE FOG ADVISORY A BIT EARLIER. TONIGHT THERE COULD BE A
RESURGENCE IN FOG AS THE STRATUS DECK BUILDS DOWN AND ANOTHER
DENSE FOG ADVISORY IS POSSIBLE.
TUESDAY...CONDITIONS SHOULD REMAIN JUST BELOW SMALL CRAFT ADVISORY
LEVELS AS A WEDGE OF HIGH PRESSURE PERSISTS INLAND WHILE A WARM
FRONT TRIES TO LIFT NORTH DURING THE AFTERNOON. SHOWERS AND/OR
THUNDERSTORMS ARE ANTICIPATED OVER THE WATERS THROUGH THE DAY. IN
GENERAL...WINDS SHOULD PEAK BETWEEN 15-20 KT WITH SEAS UP TO 3-4
FT...HIGHEST IN OFFSHORE GEORGIA WATERS.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...CONDITIONS WILL LIKELY
DETERIORATE LATE TUESDAY NIGHT INTO EARLY WEDNESDAY AS THE PRESSURE
GRADIENT TIGHTENS AND WARMER AIR PROMOTES MIXING AHEAD OF A COLD
FRONT THAT EVENTUALLY SHIFTS OVER THE WATERS WEDNESDAY
EVENING/NIGHT. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE OVER MOST
WATERS AHEAD OF THE FRONT...WHILE WINDS AND SEAS INCREASE/BUILD
WITHIN A SOUTHERLY FLOW. AT THIS TIME...CONDITIONS SHOULD REACH
SMALL CRAFT ADVISORY LEVELS FOR ALL WATERS STARTING LATE TUESDAY
NIGHT. SEAS WILL ALSO BUILD UPWARDS TO 5-8 FT INTO WEDNESDAY
AFTERNOON BEFORE THE COLD FRONT SHIFTS OFFSHORE. THERE IS STILL A
CHANCE OF GALE FORCE WIND GUSTS LATE WEDNESDAY NIGHT INTO EARLY
THURSDAY AS STRONG COLD AIR ADVECTION OCCURS BEHIND THE FRONT...BUT
CHANCES APPEAR HIGHEST IN OUTER GEORGIA WATERS. A GALE WATCH/WARNING
COULD EVENTUALLY BE NEEDED AS WINDS GUST TO 30-35 KT AWAY FROM THE
COAST.
THURSDAY AFTERNOON THROUGH SATURDAY...CONDITIONS WILL IMPROVE
QUICKLY OVER ALL WATERS AS HIGH PRESSURE BECOMES CENTERED OVER THE
SOUTHEAST. WINDS/SEAS SHOULD LOWER BELOW SMALL CRAFT ADVISORY LEVELS
FOR ALL WATERS THURSDAY AFTERNOON...THEN CONTINUE TO IMPROVE
THROUGH THE WEEKEND AS THE CENTER OF HIGH PRESSURE SLIDES OFFSHORE.
SEA FOG...MARINERS ARE ADVISED THAT LOW STRATUS DECKS AND PERIODS OF
RAIN OR DRIZZLE WILL EQUATE TO REDUCED VISIBILITIES UNTIL WEDNESDAY...
BUT THE BEST CHANCE OF CLASSIC SEA FOG COULD DEVELOP AS WARMER AIR
ARRIVES ATOP MID/UPPER 50 SHELF WATER TEMPS EARLY TUESDAY PRIOR TO
WINDS INCREASING ENOUGH TO SCOUR IT OUT TUESDAY NIGHT.
&&
.TIDES/COASTAL FLOODING...
NNE FLOW PUSHED THE CHARLESTON TIDE ABOVE 7.4 FT THIS MORNING...
MORE THAN 1 FT ANOMALY. AMAZING WHAT THE EKMAN EFFECT CAN DO TO
TIDES. THE TUESDAY MORNING HIGH TIDE IS PREDICTED AT 6.4 FT MLLW.
SIMILAR WINDS EXPECTED THEN...PERHAPS SLIGHTLY WEAKER. NEVERTHELESS
CONDITIONS LOOK PRETTY FAVORABLE FOR ANOTHER BOUT OF SHALLOW
COASTAL FLOODING SO WE ARE MENTIONING THIS IN THE HAZARDOUS
WEATHER OUTLOOK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...JRL
SHORT TERM...DPB
LONG TERM...DPB
AVIATION...JRL
MARINE...DPB/JRL
TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
306 PM CST MON DEC 22 2014
.SHORT TERM...
1227 PM CST
TONIGHT THROUGH CHRISTMAS DAY...
MAIN CHALLENGES FOR TONIGHT WILL BE ON PLACEMENT OF PRECIP ALONG
WITH HOW MUCH RAIN WILL FALL ACROSS THE FORECAST AREA. THE
NORTHERN STREAM SFC LOW HAS BECOME WRAPPED UP ACROSS THE
DAKOTAS...WITH THE MID-LVL TROUGH AXIS STRETCHING SOUTH THROUGH
THE SOUTHERN PLAINS. LLVL FLOW ACROSS THE FORECAST AREA HAS BECOME
MORE EASTERLY...WITH A FEED OF SOME SLIGHTLY DRIER AIR AT THE SFC
INTO NORTHERN IL/NORTHWEST IN. THIS HAS BEEN ABLE TO DELAY THE
ONSET OF STEADY PRECIP UNTIL LATER THIS AFTN. SFC TEMPS HAVE BEEN
SLOW TO WARM...AND LATEST GUIDANCE INDICATES THAT MAX TEMPS MAY
NOT OCCUR UNTIL JUST AFT 00Z AS A STEADY CONVEYOR OF WARMER/MOIST
AIR ADVECTS NORTH.
LOCAL SOLUTIONS BRING THE BETTER SLUG OF PRECIP INTO THE FORECAST
AREA THIS EVENING...THEN SLOWLY LIFT THE STEADIER RAIN NORTH
OVERNIGHT. QPF TOTALS HAVE DECREASED FROM EARLIER SOLUTIONS...BUT
HAVE ONLY MADE MINOR ADJUSTMENTS TO THE GOING FORECAST. THE SFC LOW
OVER THE DAKOTAS WILL BE SLIDING SOUTHEAST TOWARDS SOUTHEAST IOWA
OVERNIGHT...WITH A DRY WEDGE BECOMING ENTRAINED OVER MISSOURI.
GUIDANCE HAS BEEN LEANING TOWARDS POSSIBLY AN EARLIER ARRIVAL OF THE
DRY SLOT INTO THE FORECAST AREA JUST BEFORE DAYBREAK TUE. GIVEN THE
CONTINUED UNCERTAINTIES ON TRACK/PLACEMENT OF THE LOW...HAVE HELD
ONTO SOME LGT RAIN AT DAYBREAK THEN LIFT THE PRECIP SHIELD NORTH OF
INTO WISC BY MID-MORNING TUE. TEMPS OVERNIGHT MON SHUD BE NEARLY
STEADY...THEN AFT MIDNIGHT WITH A 850MB THERMAL RIDGE OF 3-6 DEG C
LIFTING NORTH EXPECT TEMPS TO BE SLOWLY RISING INTO THE LOW 40S.
TUE EXPECT THE SFC LOW TO BE SLOWLY WEAKENING ACROSS SOUTHWEST
WISC...WITH THE MID-LVL TROUGH AXIS EJECTING THE SECONDARY SFC LOW
ALONG THE WESTERN GULF. THIS SECONDARY LOW IS THE MAIN CONCERN FOR
WED AFTN-WED NGT ACROSS OUR REGION. THE DRY WEDGE SHUD KEEP PRECIP
WEST/NORTH OF THE FORECAST AREA THRU TUE MORNING...THEN WRAP AROUND
MOISTURE WILL BRING LGT RAIN BACK INTO THE AREA TUE AFTN/EVE. TEMPS
SHUD WARM INTO THE MID/UPR 40S...POSSIBLY TOUCHING 50 DEGREES IN THE
SOUTHEAST CWFA. THE SOUTHERN STREAM LOW WILL BE RAPIDLY DEEPENING
AND LIFTING NORTH ACROSS THE TENN VALLEY WED MORNING...THEN IT
BECOMES A CHALLENGE ON THE PLACEMENT OF THE LOW BEYOND WED MORNING.
GUIDANCE CONTINUES TO SHOW CORRECTIONS...WITH A FEW SOLUTIONS
BRINGING THE LOW NORTH INTO NORTHEAST IN AND A FEW FURTHER EAST.
THIS WILL BE A KEY PLAYER ON THE PLACEMENT OF THE POTENTIAL
DEFORMATION ZONE WHICH COULD BRING ACCUM SNOW TO THE FORECAST AREA
WED AFTN/EVE. TEMPS WILL BE FALLING DURING THE DAY WED...AND WITH
THE INCREASED FORCING...THIS COULD BR STRONG ENOUGH TO OVERCOME THE
WARMER AIR AT THE SFC AND ALLOW RAIN TO QUICKLY CHANGE TO SNOW AND
START ACCUMULATING. GEFS ENSEMBLES ARE BEGINNING TO DEMONSTRATE A
WEAK EASTERLY LLVL JET AT 850MB LIFTING NORTHEAST OVER THE FORECAST
AREA WED AFTN/EARLY EVE...WHICH WOULD SUPPORT THE IDEA OF A
DEFORMATION SNOW BAND FOR THE CENTRAL/EASTERN CWFA. CONSIDERABLE
UNCERTAINTY REMAINS WITH THIS SYSTEM...BUT EITHER WAY IT WILL IMPACT
A PORTION OF THE GREAT LAKES REGION ON ONE OF THE BUSIEST TRAVEL
DAYS OF THE YEAR.
FOR CHRISTMAS DAY...THE DOWNSTREAM RIDGE OVER THE CANADIAN MARITIME
WILL BEGIN TO WEAKEN AND ALLOW FOR THE 500MB TROUGH TO PUSH EAST OF
THE GREAT LAKES...LIFTING THE DEEPER MOISTURE/PRECIP NORTHEAST WITH
IT. MOST GUIDANCE COMES INTO SLIGHTLY BETTER AGREEMENT FOR HIGHS
ARND THE MID/UPR 30S...WITH POSSIBLY THINNING CLOUD COVER.
BEACHLER
&&
.LONG TERM...
252 PM CST
FRIDAY THROUGH MONDAY...
MAIN FORECAST CONCERNS THIS PERIOD SURROUND A PAIR OF STORM SYSTEMS.
THE FIRST TO PASS TO THE NORTH OF THE AREA FRIDAY-FRIDAY NIGHT AND
THE SECOND TO PASS TO THE SOUTH AND EAST (SHOULD CURRENT TRENDS
CONTINUE) ON SUNDAY. FIRST SURFACE LOW DEVELOPS OVER THE CENTRAL
PLAINS THURS NIGHT IN RESPONSE TO THE DIGGING UPPER TROF OVER THE
WESTERN U.S. MODELS SHOWING NRN IL GENERALLY DRY FRIDAY DURING THE
DAYTIME HOURS FRIDAY WITH MAX TEMPS RUNNING AROUND 10 DEG ABOVE
AVERAGE. A COLD FRONT THEN SWEEPS ACROSS THE AREA FRIDAY NIGHT
BRINGING A CHANCE OF RAIN OR SNOW.
MEANWHILE A SECONDARY UPPER LEVEL SHORTWAVE ROTATES INTO THE BASE
OF WESTERN U.S. TROUGH THEN ON SATURDAY AMPLIFYING THE SOUTHERN
STREAM. MODELS NOT COMPLETELY RESOLVING THIS SYSTEM YET AND HAVE
LEANED TOWARD MODEL CONSENSUS FOR A FORECAST SCENARIO WHERE A
SHARPER SHORTWAVE HELPS TO ORGANIZE SURFACE LOW PRESSURE NEAR THE
TX/LA GULF COAST SATURDAY. THIS LOW THEN MOVES NORTHEAST ACROSS
THE TN VALLEY AND INTO THE CENTRAL APPLICATIONS SUNDAY. WILL
CONFINE POPS WITH THIS SYSTEM TO JUST THE SOUTHEASTERN COUNTIES OF
THE FORECAST AREA CURRENTLY WITH TEMPS EXPECTED NEAR SEASONAL FOR
THE TIME OF YEAR.
ED F
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* CIGS LOWERING TO IFR/LIFR THIS AFTERNOON/EVENING.
* PERIODS OF RAIN THROUGH TONIGHT
* REDUCED VSBY AT TIMES 1-3 SM.
BMD
//DISCUSSION...UPDATED 18Z...
CONDITIONS ARE STEADILY DETERIORATING ALREADY WITH THE 18Z TAF
ISSUANCE AND EXPECT THIS TREND TO CONTINUE THROUGH THE AFTERNOON
HOURS. A LEAD UPPER LEVEL DISTURBANCE HAS ALLOWED RAIN TO OVERSPREAD
THE TERMINALS LATE THIS MORNING. A FEW SITES HAVE REPORTED A FEW ICE
PELLETS BUT SOUNDINGS INDICATE THE COLUMN WILL QUICKLY WARM AND WILL
NO LONGER SUPPORT FROZEN PRECIPITATION THROUGH THE REMAINDER OF THE
TAF PERIOD. CIGS ARE EXPECTED TO FAIRLY QUICKLY DROP TO IFR EARLY TO
MID AFTERNOON TODAY AND WILL REMAIN THERE OVERNIGHT. BEHIND THE LEAD
WAVE...THERE MAY BE A LULL IN THE PRECIP INTENSITY BUT MOIST
CONDITIONS AND SOME FORCING MAY RESULT IN A VERY LIGHT RAIN OR
DRIZZLE CONTINUING OVERNIGHT. THE MAIN UPPER WAVE AND WARM FRONT
WILL
LIFT ACROSS THE REGION EARLY TUESDAY RESULTING IN PRECIP INTENSITY
INCREASING ONCE AGAIN. ONCE THE WARM FRONT LIFTS NORTH OF THE
TERMINALS...PRECIP SHOULD TAPER AND THERE MAY BE A GRADUAL RISE IN
CIG HEIGHTS BACK INTO MVFR.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN GENERAL CIG TRENDS BUT LOW-MEDIUM CONFIDENCE
IN TIMING.
* LOW CONFIDENCE IN VSBY TRENDS THIS EVENING AND TONIGHT.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT...DRY. MAINLY VFR...THOUGH MVFR POSSIBLE LATE.
WEDNESDAY...CHANCE OF RA/SN CHANGING TO SN. IFR LIKELY.
THURSDAY...CHANCE OF MVFR CIGS...MAINLY EARLY.
FRIDAY...CHANCE OF MVFR CIGS. CHANCE OF -RA/-SN
SATURDAY AND SUNDAY...MAINLY VFR.
RATZER
&&
.MARINE...
305 PM CST
LOW PRESSURE OVER THE CENTRAL MISSOURI VALLEY WILL LIFT NORTHEAST
TONIGHT WHILE WEAKENING. THIS WILL RESULT IN BRISK EAST-SOUTHEAST
WINDS OVERNIGHT...WITH GUSTS UP TO 25 TO 30 KT. THE STRONGEST
EASTERLY WINDS WILL SETTLE INTO THE NORTHERN PORTION OF THE LAKE
TUESDAY MORNING...WITH WINDS TURNING SOUTHERLY ON THE SOUTH HALF.
THE LOW PRESSURE WILL DISSIPATE OVER THE NORTHERN PORTION OF THE
LAKE TUESDAY NIGHT...BRINGING QUICKLY DIMINISHING SOUTHERLY WINDS
AND A PERIOD OF LIGHT/VRB OVER THE NORTH.
ATTENTION WILL THEN TURN TO ANOTHER QUICKLY DEVELOPING LOW PRESSURE
OVER THE LOWER OHIO VALLEY ON WEDNESDAY MORNING THAT WILL LIFT NORTH
TO THE CENTRAL GREAT LAKES AND STRENGTHEN RAPIDLY INTO WEDNESDAY
NIGHT...THEN FURTHER INTENSIFY OVER WESTERN/NW QUEBEC ON THURSDAY.
MODELS HAVE COME INTO BETTER AGREEMENT ON THIS OVERALL SCENARIO AND
AM CONCERNED FOR A PERIOD OF GALES ON THE NORTHERN PORTION OF THE
LAKE WEDNESDAY NIGHT CLOSEST TO THE BOMBING LOW. HAVE NOT ISSUED A
WATCH YET DUE TO LOWER CONFIDENCE BUT IF CURRENT TRENDS HOLD WILL
LIKELY NEED A HEADLINE. NORTH-NORTHWEST GALES ARE POSSIBLE ON THE
SOUTH HALF AS WELL DEPENDING ON THE TRACK/STRENGTH OF THE LOW...BUT
CURRENT GUIDANCE SUGGESTS MORE OF A 30 KT PREVAILING/OCNL GALE GUST
SCENARIO. A FAST UPPER PATTERN SUGGESTS A FAIRLY ACTIVE PERIOD
REMAINING OVER THE LAKE INTO THE WEEKEND.
IN THE NEARSHORE...HAD EXTENDED THE SMALL CRAFT FOR THE IL ZONES
THROUGH MID MORNING TUESDAY FOR LINGERING WAVES FROM BRISK
EAST-SOUTHEAST FLOW. WILL LIKELY NEED ANOTHER SMALL CRAFT BY
WEDNESDAY AFTERNOON INTO THURSDAY FOR STRONG WINDS AND BUILDING
WAVES.
RC
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 9 AM TUESDAY.
&&
$$
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[top]
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
300 PM CST Mon Dec 22 2014
.SHORT TERM...(Tonight)
ISSUED AT 259 PM CST MON DEC 22 2014
Short-wave trough evident on 19z/1pm water vapor imagery over
Kansas/Oklahoma will lift northeastward tonight, reaching central
Illinois by 12z Tue. A large area of light rain associated with
this feature is currently ongoing across the KILX CWA: however,
radar imagery is showing the precip becoming more scattered upstream
across Missouri into southern Illinois. With a continued moist flow
and strong lift ahead of the upper wave, think numerous showers will
re-develop behind the main rain area later this afternoon into the
evening. As a result, will continue to carry categorical PoPs
across the board through the evening. After that, models agree that
a mid-level dry slot will approach from the southwest later tonight
into Tuesday morning. Both the 12z NAM and the 17z HRRR suggest the
showers will taper off and come to an end from southwest to
northeast across the area by dawn Tuesday. Will continue likely to
categorical PoPs along/north of I-74 through the entire night, but
will drop to just chance PoPs further south across the rest of the
CWA after midnight. Southerly winds of 10 to 15 mph will continue
tonight, preventing temps from dropping much. Overnight lows will
be several degrees above numeric guidance, ranging from around 40
across the north to the middle 40s south of I-70.
&&
.LONG TERM...(Tuesday through Monday)
ISSUED AT 259 PM CST MON DEC 22 2014
Model guidance continues to throw us curve balls on how the current
system will depart the area on Christmas Eve. Their spread in the
details and lack of run-to-run consistency continues to make our
confidence in Christmas Eve`s snow potential much lower than
average. There has been more than a trivial trend back toward a
snowier day in the latest runs, although this trend is far from
unanimous. The upshot is that that travel difficulties could exist
for Christmas Eve and it is prudent to monitor later forecasts
closely. While confidence is too low to issue any winter weather
headlines at this time, have issued a Special Weather Statement
highlighting the potential as well as the uncertainty.
However, the main snow threat is still a couple days off. Until
then, we will have to contend with periods of rain, although
confidence is growing that sizable breaks in the rainy periods will
occur. A dry slot wrapping around the vertically stacked
upper/surface low should support most of Tuesday, and even into
Tuesday evening, ending up dry. This dry slot is showing up nicely
as a nearly cloud free area over the central High Plains, although
we do not expect skies to be quite so clear by the time the drier
airmass arrives here. The initial upper/surface lows will dissipate
with time as a more vigorous wave rounds the base of the mean Plains
trof later Tuesday into Wednesday.
Our main snow concern arrives as the above mentioned wave heads
northeast, developing a new surface cyclone as it does so. While all
models still keep the track of the surface low east of the forecast
area, the track has shifted far enough west in most model solutions
that the deformation zone on its back side tracks across at least
east-central and southeast Illinois. However, a wide range of model
solutions exist in the timing, track, and precipitation intensity
within this deformation zone. It is also unclear if all the
precipitation within the deformation zone will fall as snow, or it
will fall as rain or a rain/snow mix for a time. Obviously, this is
critical to snow accumulation potential. While most guidance has
surface temperatures above freezing through Wednesday afternoon, the
"warm" air depth is very shallow, generally no more than 1000-1500
feet above the ground. If snowfall rates are high enough, they will
quickly be able to erode this warm layer. There are signs that
convective banding within the deformation zone is possible, which
would certainly provide high enough rates to support a quicker
change over to snow. In any event, due to the persistent
uncertainty, have gone with no more than an inch or two of snowfall
on the back side of the system, mainly east of I-55. If the latest
model trends hold, these totals will need to be boosted.
The next couple waves/precipitation threat have slowed a bit from
previous days, centering more on Saturday/Sunday than
Friday/Saturday time frame. Temperatures just ahead of the lead wave
support rain or a rain/snow mix, with conditions eventually cooling
enough for all snow. Precipitation amounts during this time appear
fairly minor for the moment.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 1151 AM CST MON DEC 22 2014
Upper wave lifting northward from Oklahoma/Texas has spread low
clouds and rain across central Illinois late this morning. Area
surface obs indicate IFR ceilings across the board. Based on 12z
forecast soundings and latest HRRR output, think IFR conditions
will prevail through the afternoon and evening with off and on
rain showers. As the upper system lifts further northward, an
approaching mid-level dry slot will bring an end to the rain from
southwest to northeast across the area after later tonight. HRRR
suggests rain will end at KSPI by 08z, then further northeast to
KCMI by around 11z. Once rain ends, have raised ceilings to MVFR
late tonight into Tuesday morning. Winds will initially be from
the southeast at 10-15kt this afternoon/evening, then will become
southerly tonight. S/SW winds of 10-15kt will prevail by Tuesday
morning.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Barnes
LONG TERM...Bak
AVIATION...Barnes
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1229 PM CST MON DEC 22 2014
.SHORT TERM...
1227 PM CST
TONIGHT THROUGH CHRISTMAS DAY...
MAIN CHALLENGES FOR TONIGHT WILL BE ON PLACEMENT OF PRECIP ALONG
WITH HOW MUCH RAIN WILL FALL ACROSS THE FORECAST AREA. THE
NORTHERN STREAM SFC LOW HAS BECOME WRAPPED UP ACROSS THE
DAKOTAS...WITH THE MID-LVL TROUGH AXIS STRETCHING SOUTH THROUGH
THE SOUTHERN PLAINS. LLVL FLOW ACROSS THE FORECAST AREA HAS BECOME
MORE EASTERLY...WITH A FEED OF SOME SLIGHTLY DRIER AIR AT THE SFC
INTO NORTHERN IL/NORTHWEST IN. THIS HAS BEEN ABLE TO DELAY THE
ONSET OF STEADY PRECIP UNTIL LATER THIS AFTN. SFC TEMPS HAVE BEEN
SLOW TO WARM...AND LATEST GUIDANCE INDICATES THAT MAX TEMPS MAY
NOT OCCUR UNTIL JUST AFT 00Z AS A STEADY CONVEYOR OF WARMER/MOIST
AIR ADVECTS NORTH.
LOCAL SOLUTIONS BRING THE BETTER SLUG OF PRECIP INTO THE FORECAST
AREA THIS EVENING...THEN SLOWLY LIFT THE STEADIER RAIN NORTH
OVERNIGHT. QPF TOTALS HAVE DECREASED FROM EARLIER SOLUTIONS...BUT
HAVE ONLY MADE MINOR ADJUSTMENTS TO THE GOING FORECAST. THE SFC LOW
OVER THE DAKOTAS WILL BE SLIDING SOUTHEAST TOWARDS SOUTHEAST IOWA
OVERNIGHT...WITH A DRY WEDGE BECOMING ENTRAINED OVER MISSOURI.
GUIDANCE HAS BEEN LEANING TOWARDS POSSIBLY AN EARLIER ARRIVAL OF THE
DRY SLOT INTO THE FORECAST AREA JUST BEFORE DAYBREAK TUE. GIVEN THE
CONTINUED UNCERTAINTIES ON TRACK/PLACEMENT OF THE LOW...HAVE HELD
ONTO SOME LGT RAIN AT DAYBREAK THEN LIFT THE PRECIP SHIELD NORTH OF
INTO WISC BY MID-MORNING TUE. TEMPS OVERNIGHT MON SHUD BE NEARLY
STEADY...THEN AFT MIDNIGHT WITH A 850MB THERMAL RIDGE OF 3-6 DEG C
LIFTING NORTH EXPECT TEMPS TO BE SLOWLY RISING INTO THE LOW 40S.
TUE EXPECT THE SFC LOW TO BE SLOWLY WEAKENING ACROSS SOUTHWEST
WISC...WITH THE MID-LVL TROUGH AXIS EJECTING THE SECONDARY SFC LOW
ALONG THE WESTERN GULF. THIS SECONDARY LOW IS THE MAIN CONCERN FOR
WED AFTN-WED NGT ACROSS OUR REGION. THE DRY WEDGE SHUD KEEP PRECIP
WEST/NORTH OF THE FORECAST AREA THRU TUE MORNING...THEN WRAP AROUND
MOISTURE WILL BRING LGT RAIN BACK INTO THE AREA TUE AFTN/EVE. TEMPS
SHUD WARM INTO THE MID/UPR 40S...POSSIBLY TOUCHING 50 DEGREES IN THE
SOUTHEAST CWFA. THE SOUTHERN STREAM LOW WILL BE RAPIDLY DEEPENING
AND LIFTING NORTH ACROSS THE TENN VALLEY WED MORNING...THEN IT
BECOMES A CHALLENGE ON THE PLACEMENT OF THE LOW BEYOND WED MORNING.
GUIDANCE CONTINUES TO SHOW CORRECTIONS...WITH A FEW SOLUTIONS
BRINGING THE LOW NORTH INTO NORTHEAST IN AND A FEW FURTHER EAST.
THIS WILL BE A KEY PLAYER ON THE PLACEMENT OF THE POTENTIAL
DEFORMATION ZONE WHICH COULD BRING ACCUM SNOW TO THE FORECAST AREA
WED AFTN/EVE. TEMPS WILL BE FALLING DURING THE DAY WED...AND WITH
THE INCREASED FORCING...THIS COULD BR STRONG ENOUGH TO OVERCOME THE
WARMER AIR AT THE SFC AND ALLOW RAIN TO QUICKLY CHANGE TO SNOW AND
START ACCUMULATING. GEFS ENSEMBLES ARE BEGINNING TO DEMONSTRATE A
WEAK EASTERLY LLVL JET AT 850MB LIFTING NORTHEAST OVER THE FORECAST
AREA WED AFTN/EARLY EVE...WHICH WOULD SUPPORT THE IDEA OF A
DEFORMATION SNOW BAND FOR THE CENTRAL/EASTERN CWFA. CONSIDERABLE
UNCERTAINTY REMAINS WITH THIS SYSTEM...BUT EITHER WAY IT WILL IMPACT
A PORTION OF THE GREAT LAKES REGION ON ONE OF THE BUSIEST TRAVEL
DAYS OF THE YEAR.
FOR CHRISTMAS DAY...THE DOWNSTREAM RIDGE OVER THE CANADIAN MARITIME
WILL BEGIN TO WEAKEN AND ALLOW FOR THE 500MB TROUGH TO PUSH EAST OF
THE GREAT LAKES...LIFTING THE DEEPER MOISTURE/PRECIP NORTHEAST WITH
IT. MOST GUIDANCE COMES INTO SLIGHTLY BETTER AGREEMENT FOR HIGHS
ARND THE MID/UPR 30S...WITH POSSIBLY THINNING CLOUD COVER.
BEACHLER
&&
.LONG TERM...
314 AM CST
TUESDAY NIGHT THROUGH SUNDAY...
DURING THIS PERIOD THE PRIMARY FOCUS WILL BE WITH THE SECOND STORM
SYSTEM EXPECTED TO DEVELOP AND IMPACT THE GREAT LAKES REGION
CHRISTMAS EVE.
A VERY IMPRESSIVE JET CORE...IN EXCESS OF 150 KT...EXTENDS FROM THE
EASTERN PACIFIC...ONSHORE OVER THE NORTHWESTERN CONUS AT THIS
TIME. THIS JET MAX IS EXPECTED TO BE THE MAIN PLAYER IN THE
DEVELOPMENT OF A SIGNIFICANT STORM SYSTEM BY MID WEEK. MODEL
SOLUTIONS (NAM ASIDE) HAVE COME INTO SOME BETTER AGREEMENT WITH THE
SURFACE LOW. OVERALL...IT APPEARS THAT CYCLOGENESIS WILL BE INDUCED
NEAR THE CENTRAL GULF COAST BY LATE TUESDAY...THEN RACE NORTHWARD
ACROSS THE OHIO VALLEY REGION AND INTO THE CENTRAL GREAT LAKES
REGION BY CHRISTMAS EVE NIGHT. IT STILL APPEARS THAT THE SURFACE LOW
WILL DEEPEN CONSIDERABLY LATE WEDNESDAY AND INTO CHRISTMAS MORNING
AS THE UPPER LEVEL IMPULSE LOOKS TO TAKE ON A NEGATIVE TILT. MOST
OPERATIONAL GUIDANCE HINTS AT HEALTHY 15 TO 20 MB DEEPENING BETWEEN
12 UTC WEDNESDAY AND 12 UTC THURSDAY.
ALTHOUGH TWEAKS TO THE TRACK AND TIMING OF THE SYSTEM ARE STILL A
POSSIBILITY...IT APPEARS THE MAIN UNCERTAINTIES AT THIS POINT WILL BE
THE MESOSCALE DETAILS...AND HENCE WHERE THE BEST DEFORMATION BANDING
WILL OCCUR LATER IN THE DAY CHRISTMAS EVE. BOTH THE GFS AND THE
PAR GFS INDICATE A SLIGHTLY FARTHER NORTH PROGRESSION OF THE
DEFORMATION BAND ACROSS MUSH OF NORTHEASTERN ILLINOIS AND
NORTHWESTERN INDIAN WED AFTERNOON AND EVENING. IN CONTRAST THE
ECMWF...GEM AND UKMET ARE A BIT FARTHER SOUTH...MAINLY IMPACTING MY
SOUTHEASTERN CWA. OVERALL...THERE IS TYPICALLY A STRONG NORTHWESTERN
GRADIENT TO THESE DEFORMATION BANDS...SO THIS COULD LEAD TO A SHARP
CONTRAST IN PRECIPITATION AMOUNTS ACROSS MY CWA.
IT APPEARS THAT PRECIPITATION TYPE WITHIN THIS DEFORMATION BAND WOULD
LIKELY BE IN THE FORM OF SNOW. MODEL SOUNDINGS SUGGEST THAT
BOUNDARY LAYER TEMPERATURES MAY REMAIN A BIT WARM LATE WEDNESDAY AND
EVENING...BUT TYPICALLY DYNAMIC COOLING FROM STRONG FORCING FOR
ASCENT WITHIN THESE DEFORMATION BANDS LEADS TO TRANSITION TO A
PERIOD OF MODERATE TO EVEN HEAVY SNOWFALL. AT THE CURRENT TIME...I
HAVE REMAINED VERY CONSERVATIVE ON SNOW AMOUNTS OVER THE AREA...DUE
TO UNCERTAINTIES ON WHERE THIS POTENTIAL BAND OF HEAVIER PRECIP SETS UP.
HOWEVER...I WOULD NOT BE SURPRISED FOR SOME AREAS...PARTICULARLY IN MY
SOUTHERN AND EASTERN CWA TO END UP WITH SEVERAL INCHES OF
SNOW BY LATE CHRISTMAS EVE. AS SUCH...CHANGES TO SNOW AMOUNTS IS A
GOOD LIKELIHOOD.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* CIGS LOWERING TO IFR/LIFR THIS AFTERNOON EVENING.
* PERIODS OF RAIN THROUGH TONIGHT
* REDUCED VSBY AT TIMES 1-3 SM.
BMD
//DISCUSSION...UPDATED 18Z...
CONDITIONS ARE STEADILY DETERIORATING ALREADY WITH THE 18Z TAF
ISSUANCE AND EXPECT THIS TREND TO CONTINUE THROUGH THE AFTERNOON
HOURS. A LEAD UPPER LEVEL DISTURBANCE HAS ALLOWED RAIN TO OVERSPREAD
THE TERMINALS LATE THIS MORNING. A FEW SITES HAVE REPORTED A FEW ICE
PELLETS BUT SOUNDINGS INDICATE THE COLUMN WILL QUICKLY WARM AND WILL
NO LONGER SUPPORT FROZEN PRECIPITATION THROUGH THE REMAINDER OF THE
TAF PERIOD. CIGS ARE EXPECTED TO FAIRLY QUICKLY DROP TO IFR EARLY TO
MID AFTERNOON TODAY AND WILL REMAIN THERE OVERNIGHT. BEHIND THE LEAD
WAVE...THERE MAY BE A LULL IN THE PRECIP INTENSITY BUT MOIST
CONDITIONS AND SOME FORCING MAY RESULT IN A VERY LIGHT RAIN OR
DRIZZLE CONTINUING OVERNIGHT. THE MAIN UPPER WAVE AND WARM FRONT WILL
LIFT ACROSS THE REGION EARLY TUESDAY RESULTING IN PRECIP INTENSITY
INCREASING ONCE AGAIN. ONCE THE WARM FRONT LIFTS NORTH OF THE
TERMINALS...PRECIP SHOULD TAPER AND THERE MAY BE A GRADUAL RISE IN
CIG HEIGHTS BACK INTO MVFR.
BMD
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN ANY MIXED PRECIP CHANGING OVER TO ALL RAIN
WITHIN NEXT HOUR.
* HIGH CONFIDENCE IN GENERAL CIG TRENDS BUT LOW-MEDIUM CONFIDENCE
IN TIMING.
* LOW CONFIDENCE IN VSBY TRENDS THIS EVENING AND TONIGHT.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT...DRY. MAINLY VFR...THOUGH MVFR POSSIBLE LATE.
WEDNESDAY...CHANCE OF RA/SN CHANGING TO SN. IFR LIKELY.
THURSDAY...CHANCE OF MVFR CIGS...MAINLY EARLY.
FRIDAY...CHANCE OF MVFR CIGS. CHANCE OF -RA/-SN
SATURDAY AND SUNDAY...MAINLY VFR.
RATZER
&&
.MARINE...
233 AM CST
FORECAST FOR LAKE MICHIGAN REMAINS COMPLICATED THIS MORNING...WITH
TWO AREAS OF LOW PRESSURE EXPECTED TO BRING PERIODS OF STRONG WINDS
ACROSS THE LAKE OVER THE NEXT SEVERAL DAYS.
THE FIRST LOW WAS MOVING SOUTHEAST ACROSS THE DAKOTAS EARLY THIS
MORNING...WITH A TIGHTENING PRESSURE GRADIENT EXTENDING EAST INTO
THE WESTERN LAKES. OBSERVATION PLATFORMS ALONG THE WEST AND
NORTHWEST SHORES OF THE LAKE WERE REPORTING SOUTH WINDS IN THE 25-30
KT RANGE...WITH WINDS TO 30 KT EXPECTED TO BACK TO THE EAST AS THE
LOW MOVES TO THE IOWA-MISSOURI BORDER TONIGHT. THE LOW WILL THEN
BEGIN TO FILL AS IT TURNS NORTHEAST...LIFTING ACROSS NORTHERN LAKE
MICHIGAN LATE TUESDAY.
EXPECTATIONS ARE THAT A SECOND LOW WILL DEVELOP TO THE SOUTH ACROSS
THE TENNESSEE AND OHIO RIVER VALLEYS BY EARLY WEDNESDAY MORNING...
DEEPENING AS IT LIFTS NORTHWARD INTO THE CENTRAL GREAT LAKES REGION
BY WEDNESDAY EVENING. MODELS CONTINUE TO SHOW DIFFERENCES IN THE
EXACT TRACK AND STRENGTH OF THE LOW AS IT PASSES EAST OF LAKE
MICHIGAN...AS WELL AS NORTH AND NORTHWEST WIND SPEEDS WEDNESDAY
AFTERNOON INTO THURSDAY MORNING. AT THIS POINT...IT APPEARS THAT
WINDS OF 25-30 KT ARE LIKELY...AND POSSIBLY STILL GALES FOR A TIME
IF THE LOW DEEPENS A LITTLE FASTER. WINDS THEN LOOK TO DIMINISH AND
BACK TO THE WEST AND THEN SOUTHWEST CHRISTMAS DAY. MODELS ARE IN
BETTER AGREEMENT IN ANOTHER LOW APPROACHING AND LIFTING ACROSS THE
NORTHERN LAKES FRIDAY AND FRIDAY NIGHT.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 9 AM TUESDAY.
&&
$$
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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1151 AM CST Mon Dec 22 2014
.UPDATE...
ISSUED AT 904 AM CST MON DEC 22 2014
Made a quick update to the forecast to increase PoPs to 100
percent as light rain has already spread across much of the KILX
CWA. The exceptions are northwest of the Illinois River and
further east near the Indiana border. Based on radar trends and
latest HRRR and NAM forecasts, light rain will spread across the
remainder of the area over the next couple of hours. May see a
brief period of a rain/sleet mix northeast of I-74 near Rantoul
and Danville as the precip initially begins, but it will quickly
transition to all rain. Also made a few tweaks to hourly temps and
lowered afternoon highs by a couple of degrees due to rain and a
continued E/SE flow. Highs will reach the lower to middle 40s.
&&
.SHORT TERM...(Today)
ISSUED AT 501 AM CST MON DEC 22 2014
Strong jet (175kts) over the Pacific Northwest digging southeast
into a deepening central Plains trof this morning will eject an
initial wave into our area today bringing rain along with mild
temperatures. Low pressure is expected to consolidate over north
central Missouri by late this afternoon and then track thru
northwest Illinois early this evening. The southerly flow in advance
of the storm system will quickly saturate the lower levels of the
atmosphere with rain overspreading the area from southwest to
northeast this morning. Some weak isentropic lift and moisture
convergence early this morning has produced some spotty light
rain/drizzle over parts of central Illinois and expect that to
continue before the stronger forcing arrives later this morning.
Models suggest the strongest lift moves into our area from mid
morning thru the early evening hours, so high POPs are warranted
over most of the forecast area today. Despite the cloud cover and
precip, mild temperatures to prevail again today with afternoon
readings in the mid to upper 40s.
&&
.LONG TERM...(Tonight through Sunday)
ISSUED AT 501 AM CST MON DEC 22 2014
Increased rain chances to categorical this evening with supporting
lift of low level jet and short waves ejecting ne from
central/southern plains into IL tonight. Rain chances to diminish
from sw to ne during overnight into Tue morning as energy shifts
north of central IL Tue. Appears to be a lull in rain chances Tue
and Tue evening over much of central IL with best rain chances
shifting to our north with surface low pressure over southern WI Tue
afternoon and also to our se. Mild lows tonight of 40-45F and highs
Tue range from mid 40s over IL river valley and lower 50s in
southeast IL.
00Z models still not in good agreement with development of strong
low pressure system from northwestern Gulf of Mexico and deepening
nne across the ohio river valley Wed. NAM model appears is dry over
IL Tue night and Wed but feel its low pressure track is too far east
near the foothills of the Appalachians. Will use a blend of the
ECMWF/GEM and GFS models for the storm system during midweek. Have
precipitation chances spreading back northward across central IL
overnight Tue night into Wed and diminishing from west to east by
overnight Wed night. Warm enough for rain Tue evening, then mixing
with and gradually changing to light snow later Tue night into Wed
from west to east. Deformation band of light snow accumulations
likely to set up on back side of storm system, though placement of
this band is still too difficult to pinpoint down. WPC keeps snow
accumulations less than 1 inch over central/eastern IL on
Wed/Christmas eve. Cooler highs Wed in the upper 30s to near 40F
eastern IL and will likely slip during the afternoon with increasing
WNW winds.
Christmas Day still looks dry with return of some sunshine as strong
storm system lifts into Quebec and 1025 mb surface high pressure
over gulf of mexico ridges northward into the ohio river valley.
Highs in the lower 40s Thu/Christmas Day, so any snow that does fall
Wed will likely melt.
Models have another low pressure taking a track more nw of central
IL Friday and lifting into the western Great Lakes Friday night.
Have small chances of light precipitation Fri/Fri night and then dry
for the weekend. Models showing yet another southern low pressure
system over gulf of Mexico Sat night/Sunday but for now will keep
precipitation chances south of central IL.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 1151 AM CST MON DEC 22 2014
Upper wave lifting northward from Oklahoma/Texas has spread low
clouds and rain across central Illinois late this morning. Area
surface obs indicate IFR ceilings across the board. Based on 12z
forecast soundings and latest HRRR output, think IFR conditions
will prevail through the afternoon and evening with off and on
rain showers. As the upper system lifts further northward, an
approaching mid-level dry slot will bring an end to the rain from
southwest to northeast across the area after later tonight. HRRR
suggests rain will end at KSPI by 08z, then further northeast to
KCMI by around 11z. Once rain ends, have raised ceilings to MVFR
late tonight into Tuesday morning. Winds will initially be from
the southeast at 10-15kt this afternoon/evening, then will become
southerly tonight. S/SW winds of 10-15kt will prevail by Tuesday
morning.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Barnes
SHORT TERM...Smith
LONG TERM...07
AVIATION...Barnes
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1013 AM CST MON DEC 22 2014
.SHORT TERM...
314 AM CST
TODAY THROUGH TUESDAY...
THE MAIN CONCERNS DURING THIS PERIOD CONTINUE TO BE FOCUSED ON
RAINFALL AMOUNTS AND TIMING.
WATER VAPOR IMAGERY EARLY THIS MORNING INDICATES SEVERAL SMALLER
SCALE MID LEVEL VORT IMPULSES MOVING WITHIN THE LARGER SCALE TROUGH
ENCOMPASSING MUCH OF THE CENTRAL CONUS FROM THE ROCKIES EASTWARD TO
THE MISSISSIPPI VALLEY. ONE SUCH IMPULSE IS CURRENT SHIFTING ACROSS
THE AREA...AND THIS HAS ACTED TO SPARK OFF SOME LIGHT PRECIPITATION
ACROSS PORTIONS OF THE AREA OVER THE PAST COUPLE HOURS. MOST SURFACE
OBSERVATIONS UNDER THE RADAR ECHOS HAVE REPORTED RAIN OR DRIZZLE.
HOWEVER...WITH SURFACE TEMPERATURES HOVERING RIGHT AT FREEZING
ACROSS MUCH OF NORTHERN ILLINOIS...SOME AREAS COULD BE EXPERIENCING
SOME MINOR GLAZING. THIS INITIAL DISTURBANCE SHOULD MOVE NORTHEAST
OF THE AREA BY DAYBREAK...SO THERE WILL LIKELY BE A LULL IN THE
PRECIPITATION FOR SEVERAL HOURS THIS MORNING AFTER AROUND
DAYBREAK...THROUGH MID TO LATE MORNING. THEREAFTER...A SECOND MID
LEVEL IMPULSE...CURRENTLY NOTED ACROSS EASTERN PORTIONS OF
OKLAHOMA...WILL SHIFT NORTH-NORTHEASTWARD TOWARDS THE AREA BY THIS
AFTERNOON.
THIS SECOND DISTURBANCE WILL BE ACCOMPANIED BY A BETTER INFLUX OF
MOISTURE...ALLOWING FOR MORE WIDESPREAD RAIN DEVELOPMENT ACROSS
CENTRAL PORTIONS OF ILLINOIS AND INDIANA BY LATE MORNING...BEFORE
SHIFTING NORTHWARD ALL OF NORTHERN ILLINOIS/NORTHWESTERN INDIANA BY
EARLY THIS AFTERNOON. THEREFORE...A VERY WET AFTERNOON IS IN STORE
FOR THE AREA. IT IS STILL POSSIBILITY THAT AS THIS BACH OF PRECIPITATION
BEGINS TO ENTER FAR NORTHERN SECTIONS OF ILLINOIS LATER THIS
MORNING...THAT IT COULD ONSET AS A MIX OF SLEET...SNOW AND RAIN.
MODEL SOUNDINGS INDICATE PROFILES SPORTIVE OF SUCH FOR A SMALL WINDOW
OF TIME THROUGH AROUND MIDDAY. A SURGE OF A WARMER AND MOIST AIRMASS
WILL END THIS BY EARLY AFTERNOON AS ALL RAIN WILL BE FAVORED
AREA-WIDE.
AS WE HEAD INTO THE EVENING ANOTHER BACH OF RAINFALL IS EXPECTED TO
DEVELOP NORTHWARD ACROSS THE AREA. THIS ADDITIONAL RAINFALL WILL BE
DRIVEN BY YET ANOTHER INFLUX OF AN EVEN WARMER MORE MOIST AIRMASS
OUT AHEAD OF A CLOSING OFF MID LEVEL CIRCULATION OVER THE MID
MISSOURI VALLEY. THIS PROCESS WILL ALSO DRIVE ADDITIONAL MID LEVEL
IMPULSES NORTHEASTWARD ALONG ITS SOUTHEASTERN PERIPHERY RIGHT ACROSS
THE AREA. AT THE SURFACE...LOW PRESSURE WILL SHIFT FROM THE NORTHERN
PLAINS TO THE IOWA...MISSOURI STATE LINE BY THIS EVENING...THEN LIFT
A WARM/OCCLUDED FRONTAL BOUNDARY NORTHWARD ACROSS THE AREA BY
DAYBREAK TUESDAY. ONCE THIS FRONTAL BOUNDARY LIFTS OVER THE
AREA...AN ACCOMPANYING MID LEVEL DRY SLOT IS EXPECTED TO SHIFT OVER
THE AREA...BRINGING AN END TO MUCH OF THE RAINFALL EITHER VERY LATE
TONIGHT OR EARLY TUESDAY MORNING. THEREFORE...MUCH OF THE DAY
TUESDAY LOOKS TO BE CLOUDY...MILD AND ASIDE FROM THE POSSIBILITY FOR
SOME LINGERING DRIZZLE...MAINLY DRY.
TOTAL RAINFALL AMOUNTS WITH THIS ACTIVITY THIS AFTERNOON INTO
TONIGHT COULD RANGE BETWEEN A HALF INCH AND ONE INCH...AS SOME
PERIODS OF MODERATE RAIN ARE POSSIBLE INTO THIS EVENING AS PWATS
CREEP UP IN EXCESS OF 3/4 OF AN INCH. I HAVE ATTEMPTED TO FOCUS THE
BEST CHANCES FOR RAINFALL FROM MID TO LATE MORNING THROUGH LATER
TONIGHT ACROSS MY CENTRAL ILLINOIS COUNTIES...AND FROM AROUND MIDDAY
THROUGH TONIGHT FOR MY NORTHERN AREAS.
KJB
&&
.LONG TERM...
314 AM CST
TUESDAY NIGHT THROUGH SUNDAY...
DURING THIS PERIOD THE PRIMARY FOCUS WILL BE WITH THE SECOND STORM
SYSTEM EXPECTED TO DEVELOP AND IMPACT THE GREAT LAKES REGION
CHRISTMAS EVE.
A VERY IMPRESSIVE JET CORE...IN EXCESS OF 150 KT...EXTENDS FROM THE
EASTERN PACIFIC...ONSHORE OVER THE NORTHWESTERN CONUS AT THIS
TIME. THIS JET MAX IS EXPECTED TO BE THE MAIN PLAYER IN THE
DEVELOPMENT OF A SIGNIFICANT STORM SYSTEM BY MID WEEK. MODEL
SOLUTIONS (NAM ASIDE) HAVE COME INTO SOME BETTER AGREEMENT WITH THE
SURFACE LOW. OVERALL...IT APPEARS THAT CYCLOGENESIS WILL BE INDUCED
NEAR THE CENTRAL GULF COAST BY LATE TUESDAY...THEN RACE NORTHWARD
ACROSS THE OHIO VALLEY REGION AND INTO THE CENTRAL GREAT LAKES
REGION BY CHRISTMAS EVE NIGHT. IT STILL APPEARS THAT THE SURFACE LOW
WILL DEEPEN CONSIDERABLY LATE WEDNESDAY AND INTO CHRISTMAS MORNING
AS THE UPPER LEVEL IMPULSE LOOKS TO TAKE ON A NEGATIVE TILT. MOST
OPERATIONAL GUIDANCE HINTS AT HEALTHY 15 TO 20 MB DEEPENING BETWEEN
12 UTC WEDNESDAY AND 12 UTC THURSDAY.
ALTHOUGH TWEAKS TO THE TRACK AND TIMING OF THE SYSTEM ARE STILL A
POSSIBILITY...IT APPEARS THE MAIN UNCERTAINTIES AT THIS POINT WILL BE
THE MESOSCALE DETAILS...AND HENCE WHERE THE BEST DEFORMATION BANDING
WILL OCCUR LATER IN THE DAY CHRISTMAS EVE. BOTH THE GFS AND THE
PAR GFS INDICATE A SLIGHTLY FARTHER NORTH PROGRESSION OF THE
DEFORMATION BAND ACROSS MUSH OF NORTHEASTERN ILLINOIS AND
NORTHWESTERN INDIAN WED AFTERNOON AND EVENING. IN CONTRAST THE
ECMWF...GEM AND UKMET ARE A BIT FARTHER SOUTH...MAINLY IMPACTING MY
SOUTHEASTERN CWA. OVERALL...THERE IS TYPICALLY A STRONG NORTHWESTERN
GRADIENT TO THESE DEFORMATION BANDS...SO THIS COULD LEAD TO A SHARP
CONTRAST IN PRECIPITATION AMOUNTS ACROSS MY CWA.
IT APPEARS THAT PRECIPITATION TYPE WITHIN THIS DEFORMATION BAND WOULD
LIKELY BE IN THE FORM OF SNOW. MODEL SOUNDINGS SUGGEST THAT
BOUNDARY LAYER TEMPERATURES MAY REMAIN A BIT WARM LATE WEDNESDAY AND
EVENING...BUT TYPICALLY DYNAMIC COOLING FROM STRONG FORCING FOR
ASCENT WITHIN THESE DEFORMATION BANDS LEADS TO TRANSITION TO A
PERIOD OF MODERATE TO EVEN HEAVY SNOWFALL. AT THE CURRENT TIME...I
HAVE REMAINED VERY CONSERVATIVE ON SNOW AMOUNTS OVER THE AREA...DUE
TO UNCERTAINTIES ON WHERE THIS POTENTIAL BAND OF HEAVIER PRECIP SETS UP.
HOWEVER...I WOULD NOT BE SURPRISED FOR SOME AREAS...PARTICULARLY IN MY
SOUTHERN AND EASTERN CWA TO END UP WITH SEVERAL INCHES OF
SNOW BY LATE CHRISTMAS EVE. AS SUCH...CHANGES TO SNOW AMOUNTS IS A
GOOD LIKELIHOOD.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* VFR LOWERING TO IFR AND POSSIBLY LIFR THIS EVENING.
* RAIN DEVELOPING OVER NEXT COUPLE HOURS CONTINUING INTO TONIGHT.
* SOUTHEAST WINDS AROUND 10 KT BECOMING EAST-SOUTHEAST 10-15 KT
BY AFTERNOON.
RATZER/DEUBELBEISS
//DISCUSSION...UPDATED 12Z...
LOW PRESSURE MOVING SOUTHEAST FROM THE DAKOTAS TO THE MIDWEST
TODAY...WITH RAIN AND LOW CIGS/VSBY EXPECTED TO DEVELOP FROM THE
SOUTHWEST BY MIDDAY/EARLY AFTERNOON AS MOISTURE SPREADS INTO THE
REGION AHEAD OF THE LOW. SOME SPOTTY LIGHT PRECIP MAINLY WEST AND
NORTHWEST OF CHICAGO TERMINALS EARLY THIS MORNING...WITH MARGINAL
THERMAL PROFILES SUPPORTING LIGHT RAIN/LIGHT SNOW/LIGHT SLEET.
PRECIPITATION TO BECOME ALL RAIN BY AFTERNOON WITH TEMPS RISING
WELL ABOVE FREEZING. RAIN CONTINUES INTO TONIGHT AND TAPERS TO
DRIZZLE AT TIMES OVERNIGHT.
VFR CIGS WITH SOME MVFR VSBY IN HAZE EARLY THIS MORNING...WITH
CIGS/VSBY EXPECTED TO DETERIORATE TO IFR THIS AFTERNOON AFTER RAIN
DEVELOPS AND LIKELY TO LIFR OVERNIGHT. SOME IMPROVEMENT EXPECTED
TUESDAY MORNING AS WARM FRONT LIFTS NORTH OF TERMINALS.
SOUTHEAST WINDS NEAR 10 KT THIS MORNING TO BECOME EAST-SOUTHEAST
TODAY AND TONIGHT 10-15 KTS. WINDS TURN BACK TO THE SOUTH AND
EVENTUALLY SOUTHWEST TUESDAY MORNING WITH WARM FRONT PASSAGE.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM IN CIGS THROUGH PERIOD...THOUGH MEDIUM LOW IN TIMING
SHIFT TO IFR AND LIFR.
* MEDIUM-HIGH IN GENERAL PRECIP TIMING AND WIND TRENDS.
RATZER/DEUBELBEISS
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT...DRY. MAINLY VFR...THOUGH MVFR POSSIBLE LATE.
WEDNESDAY...CHANCE OF RA/SN CHANGING TO SN. IFR LIKELY.
THURSDAY...CHANCE OF MVFR CIGS...MAINLY EARLY.
FRIDAY...CHANCE OF MVFR CIGS. CHANCE OF -RA/-SN
SATURDAY AND SUNDAY...MAINLY VFR.
RATZER
&&
.MARINE...
233 AM CST
FORECAST FOR LAKE MICHIGAN REMAINS COMPLICATED THIS MORNING...WITH
TWO AREAS OF LOW PRESSURE EXPECTED TO BRING PERIODS OF STRONG WINDS
ACROSS THE LAKE OVER THE NEXT SEVERAL DAYS.
THE FIRST LOW WAS MOVING SOUTHEAST ACROSS THE DAKOTAS EARLY THIS
MORNING...WITH A TIGHTENING PRESSURE GRADIENT EXTENDING EAST INTO
THE WESTERN LAKES. OBSERVATION PLATFORMS ALONG THE WEST AND
NORTHWEST SHORES OF THE LAKE WERE REPORTING SOUTH WINDS IN THE 25-30
KT RANGE...WITH WINDS TO 30 KT EXPECTED TO BACK TO THE EAST AS THE
LOW MOVES TO THE IOWA-MISSOURI BORDER TONIGHT. THE LOW WILL THEN
BEGIN TO FILL AS IT TURNS NORTHEAST...LIFTING ACROSS NORTHERN LAKE
MICHIGAN LATE TUESDAY.
EXPECTATIONS ARE THAT A SECOND LOW WILL DEVELOP TO THE SOUTH ACROSS
THE TENNESSEE AND OHIO RIVER VALLEYS BY EARLY WEDNESDAY MORNING...
DEEPENING AS IT LIFTS NORTHWARD INTO THE CENTRAL GREAT LAKES REGION
BY WEDNESDAY EVENING. MODELS CONTINUE TO SHOW DIFFERENCES IN THE
EXACT TRACK AND STRENGTH OF THE LOW AS IT PASSES EAST OF LAKE
MICHIGAN...AS WELL AS NORTH AND NORTHWEST WIND SPEEDS WEDNESDAY
AFTERNOON INTO THURSDAY MORNING. AT THIS POINT...IT APPEARS THAT
WINDS OF 25-30 KT ARE LIKELY...AND POSSIBLY STILL GALES FOR A TIME
IF THE LOW DEEPENS A LITTLE FASTER. WINDS THEN LOOK TO DIMINISH AND
BACK TO THE WEST AND THEN SOUTHWEST CHRISTMAS DAY. MODELS ARE IN
BETTER AGREEMENT IN ANOTHER LOW APPROACHING AND LIFTING ACROSS THE
NORTHERN LAKES FRIDAY AND FRIDAY NIGHT.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 9 AM TUESDAY.
SMALL CRAFT ADVISORY...LMZ741-LMZ742 UNTIL 9 AM TUESDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
904 AM CST Mon Dec 22 2014
.UPDATE...
ISSUED AT 904 AM CST MON DEC 22 2014
Made a quick update to the forecast to increase PoPs to 100
percent as light rain has already spread across much of the KILX
CWA. The exceptions are northwest of the Illinois River and
further east near the Indiana border. Based on radar trends and
latest HRRR and NAM forecasts, light rain will spread across the
remainder of the area over the next couple of hours. May see a
brief period of a rain/sleet mix northeast of I-74 near Rantoul
and Danville as the precip initially begins, but it will quickly
transition to all rain. Also made a few tweaks to hourly temps and
lowered afternoon highs by a couple of degrees due to rain and a
continued E/SE flow. Highs will reach the lower to middle 40s.
&&
.SHORT TERM...(Today)
ISSUED AT 501 AM CST MON DEC 22 2014
Strong jet (175kts) over the Pacific Northwest digging southeast
into a deepening central Plains trof this morning will eject an
initial wave into our area today bringing rain along with mild
temperatures. Low pressure is expected to consolidate over north
central Missouri by late this afternoon and then track thru
northwest Illinois early this evening. The southerly flow in advance
of the storm system will quickly saturate the lower levels of the
atmosphere with rain overspreading the area from southwest to
northeast this morning. Some weak isentropic lift and moisture
convergence early this morning has produced some spotty light
rain/drizzle over parts of central Illinois and expect that to
continue before the stronger forcing arrives later this morning.
Models suggest the strongest lift moves into our area from mid
morning thru the early evening hours, so high POPs are warranted
over most of the forecast area today. Despite the cloud cover and
precip, mild temperatures to prevail again today with afternoon
readings in the mid to upper 40s.
&&
.LONG TERM...(Tonight through Sunday)
ISSUED AT 501 AM CST MON DEC 22 2014
Increased rain chances to categorical this evening with supporting
lift of low level jet and short waves ejecting ne from
central/southern plains into IL tonight. Rain chances to diminish
from sw to ne during overnight into Tue morning as energy shifts
north of central IL Tue. Appears to be a lull in rain chances Tue
and Tue evening over much of central IL with best rain chances
shifting to our north with surface low pressure over southern WI Tue
afternoon and also to our se. Mild lows tonight of 40-45F and highs
Tue range from mid 40s over IL river valley and lower 50s in
southeast IL.
00Z models still not in good agreement with development of strong
low pressure system from northwestern Gulf of Mexico and deepening
nne across the ohio river valley Wed. NAM model appears is dry over
IL Tue night and Wed but feel its low pressure track is too far east
near the foothills of the Appalachians. Will use a blend of the
ECMWF/GEM and GFS models for the storm system during midweek. Have
precipitation chances spreading back northward across central IL
overnight Tue night into Wed and diminishing from west to east by
overnight Wed night. Warm enough for rain Tue evening, then mixing
with and gradually changing to light snow later Tue night into Wed
from west to east. Deformation band of light snow accumulations
likely to set up on back side of storm system, though placement of
this band is still too difficult to pinpoint down. WPC keeps snow
accumulations less than 1 inch over central/eastern IL on
Wed/Christmas eve. Cooler highs Wed in the upper 30s to near 40F
eastern IL and will likely slip during the afternoon with increasing
WNW winds.
Christmas Day still looks dry with return of some sunshine as strong
storm system lifts into Quebec and 1025 mb surface high pressure
over gulf of mexico ridges northward into the ohio river valley.
Highs in the lower 40s Thu/Christmas Day, so any snow that does fall
Wed will likely melt.
Models have another low pressure taking a track more nw of central
IL Friday and lifting into the western Great Lakes Friday night.
Have small chances of light precipitation Fri/Fri night and then dry
for the weekend. Models showing yet another southern low pressure
system over gulf of Mexico Sat night/Sunday but for now will keep
precipitation chances south of central IL.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
ISSUED AT 515 AM CST MON DEC 22 2014
Deteriorating conditions expected across the area this morning
as a storm system tracks into the region. Mostly VFR cigs being
reported early this morning but expect those to transition to
MVFR and then IFR from south to north after 15z this morning as
rain increases in coverage over our area. We expect IFR to LIFR
conditions this afternoon into tonight as the rain continues on
and off thru 00z. In the 03z-06z, the rain is expected to taper
off with a lull in the precip after 06z as the storm system shifts
north of our area overnight. Surface winds will be east to southeast
today at 10 to 15 kts with a few gusts around 20 kts later this
morning into the afternoon hours. Southeast winds of 10 to 15 kts
can be expected tonight.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Barnes
SHORT TERM...Smith
LONG TERM...07
AVIATION...Smith
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
103 PM EST MON DEC 22 2014
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 425 AM EST MON DEC 22 2014
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW SW FLOW ALOFT OVER
THE WRN GREAT LKS TO THE E OF A DEEPENING UPR TROF IN THE CENTRAL
CONUS CAUSED BY SHRTWVS DIGGING SEWD IN NW FLOW ALOFT E OF UPR RDG
ALONG THE W COAST. SHRTWV RESPONSIBLE FOR THE SN ON SUN EVNG IS
LIFTING NEWD THRU NW ONTARIO. AS THE ACCOMPANYING STRONGER DYNAMIC
FORCING SHIFTS TO THE NE...IR STLT IMAGERY SHOWS WARMING CLD TOP
TEMPS AS THE COMMA TAIL MSTR BAND SHIFTS TO THE E. ALTHOUGH RADAR
SHOWS THE HEAVIER PCPN IS FOLLOWING OFF TO THE NE...SOME PATCHY
ECHOES REMAIN OVER MUCH OF THE CWA. COMPOSITE RADAR INDICATES
GENERALLY LIGHT MIXED PCPN STRETCHES OFF TO THE SW THRU MUCH OF THE
NW HALF OF WI...WHERE MODELS SHOW AN AXIS OF WEAKER DEEP LYR QVECTOR
CNVGC. SFC OBS INDICATE LOWER SFC DEWPTS OVER NRN LOWER MI...UPWIND
OF THE E HALF OF THE CWA.
MAIN FCST CONCERNS TODAY FOCUS ON DIMINISHING PCPN TRENDS. FOCUS FOR
TNGT SHIFTS TO TIMING THE ARRIVAL OF ANOTHER AREA OF SN/MIXED PCPN
AS ANOTHER SHRTWV LIFTS NEWD OUT OF DEEPENING UPR TROF THAT CAUSES A
CLOSED H5 LO TO DEVELOP IN THE CENTRAL PLAINS.
TODAY...EXPECT SOME GENERALLY LGT SN/MIXED WITH RA TO IMPACT MAINLY
THE W HALF OF THE CWA THRU THIS MRNG AWAY FM THE DRIER NEAR SFC AIR
ADVECTING INTO THE ERN ZNS AND UNDER LINGERING BUT SLOWLY FADING
DEEP LYR QVECTOR CNVGC AS SHRTWV RDG APRCHS FM THE SW. DURING THE
AFTN...ARRIVAL OF DRIER AIR ALOFT FM THE S WITHIN THE NVA SHOULD END
ANY LINGERNING LARGE SCALE PCPN. BUT CONCERNED SOME SN GRAINS/
FREEZING DZ/DZ WL LINGER OVER MAINLY THE CENTRAL CWA WITH UPSLOPE SE
FLOW OFF LK MI. THIS POTENTIAL WL BE LIMITED BY ADVECTION OF LOWER
H95-9 SPECIFIC HUMIDITY NOW OVER NRN LOWER MI...ESPECIALLY OVER THE
E HALF AND BY LATE AFTN EVEN OVER THE CENTRAL. EXPECT TEMPS TO TOP
OUT ABOVE FREEZING EVERYWHERE...SO ANY FREEZING DZ SHOULD END BY
NOON OR SO.
TNGT...AS AREA OF SGNFT DEEP LYR QVECTOR CNVGC/DEEP ISENTROPIC
ASCENT/UPR DVGC IN ADVANCE OF SHRTWV LIFTING NE TOWARD THE GREAT LKS
OVERSPREADS THE AREA...EXPECT PCPN TO DEVELOP OVER THE SCENTRAL BY
MIDNGT AND THEN SPREAD TO OVER ALL THE KEWEENAW BY 12Z TUE. PER NCEP
PREFERENCE...TENDED TOWARD THE 00Z NAM FOR FCST DETAILS. THIS MODEL
GENERATES ABOUT 0.25 INCH OF TOTAL QPF AT MENOMINEE BY 12Z TUE.
PTYPE IS A CONCERN. WHILE THE NAM FCST SDNG FOR MENOMINEE INDICATES
MAINLY RA FOR THAT LOCATION...MODEL SDNGS/H100-85 THKNS INDICATE
AREAS AWAY FM LK MI WL SEE MAINLY SN THRU 12Z TUE. ARRIVAL OF LLVL
DRY AIR TODAY THAT WL ENHANCE NEAR SFC EVAPORATIVE COOLING AND
BACKING NEAR SFC FLOW TOWARD THE ENE THAT WL CUTOFF THE ARRIVAL OF
WARMER AIR APPEAR TO BE THE REASON THE LLVL TEMPS TREND COLD ENUF
FOR MAINLY SN EXCEPT NEAR LK MI. SN/WATER RATIOS WL BE LIMITED BY
RELATIVELY HI/THIN DGZ...SO AN INCH OR TWO OF SN WL LIKELY
ACCUMULATE BY SUNRISE OVER MUCH OF THE SE HALF OF THE CWA TO THE NW
OF THE RA/SN LINE.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 438 AM EST MON DEC 22 2014
...WIDESPREAD MODERATE SNOW ON TUESDAY...
ONE PRIMARY CHANCE FOR ACCUMULATING SNOW OVER ALL OF CWA IN THE LONG
TERM ON TUESDAY BUT CANNOT RULE OUT MORE SNOW CHIRSTMAS EVE FOR
EASTERN CWA AS THE ON AGAIN OFF AGAIN LOW PRESSURE SYSTEM IS STILL
AROUND IN LATEST MODELS. ANOTHER SYSTEM MAY IMPACT REGION WITH SWATH
OF SNOW FRIDAY INTO SATURDAY...BUT LACK OF CONTINUITY FM THE MODELS
LIMITS CONFIDENCE IN THAT PART OF FORECAST ATTM.
EVOLVING LOW PRESSURE SYSTEM MOVING OUT OF THE PLAINS TUESDAY INTO
WEDNESDAY APPEARS MORE LIKE RECENT RUNS OF ECMWF. QUESTION IS HOW
FAR EAST THE MID-LEVEL AND SFC LOWS REACH ON TUESDAY AS THAT IMPACTS
DRY SLOT AND PRECIP INTENSITY...ESPECIALLY OVER THE SOUTHERN PART OF
CWA. BLEND OF NAM/SREF SUPPORTED BY NCEP AND LOOKED LIKE 12Z ECMWF.
PRIMARY SHORTWAVE AND SFC LOW MOVE TO EASTERN IOWA BY 12Z TUESDAY
AND LIFT ACROSS EASTERN WISCONSIN ON TUESDAY AFTN. CIRCULATION AROUND
SFC-H85 LOWS PULLS H7 MIXING RATIOS OVER 3G/KG NORTH OF THE LOWS OVER
MAJORITY OF UPR MICHIGAN. PER GARCIA METHOD WITH NO PTYPE
CONSIDERATIONS THAT WOULD FAVOR 3 INCHES OF SNOW IN 6 HRS. BLEND OF
FAVORED QPFS POINT TO 0.30-0.50 INCH OF LIQUID EQUIVALENT OVER MOST
CWA...WITH HIGHER AMOUNTS OVER 0.50 INCH OVER FAR WEST AND SCNTRL.
TROUBLE IS 00Z ECMWF TRENDED EAST WITH SFC LOW AND HAS DRY SLOT INTO
SCNTRL...REALLY CUTTING ITS PRECIP THERE.
PTYPE ALSO AN ISSUE...UNFORTUNATELY. SOUNDINGS FM NAM KEEP BLYR
COOL...WITH ONLY SURE CHANGE TO RAIN AT MNM WITH ENE FLOW OFF BAY OF
GREEN BAY. ENE WINDS WOULD LEAD TO COOLING TO PERSIST AT KESC AND
KISQ. GFS SIMILAR WHILE GEM-REGIONAL IS MUCH WARMER/WESTWARD WITH
1000-850MB THICKNESSES OVER 1305M. SINCE WINDS ARE BACKING AND OFF
LAND IN LOW-LAYERS WILL FAVOR COOLER IDEA OFFERED BY NAM/GFS IN THE
MORNING BUT WILL BRING MORE GEM IDEA IN THE AFTN AS SFC LOW EDGES
CLOSER TO THE AREA FM THE SOUTH. RESULT WILL BE RAIN/SNOW MIX OVER
SCNTRL UPR MICHIGAN ALONG BAY OF GREEN BAY...WITH SNOW ELSEWHERE
INTO EARLY AFTN...THEN GO FOR A MIX OF RAIN AND SNOW OVER MOST OF
THE EAST HALF CWA BY MID AFTN. NAM SOUNDINGS SHOW THE SNOW MAY LAST
THROUGH THE DAY OVER MOST OF THE WEST HALF OF CWA AND EVEN FOLLOWING
GEM THICKNESSES QPF THAT OCCURS THERE IN THE MORNING WOULD STAY ALL
SNOW. OVERALL...WILL LEAN TOWARD MOST SNOW OVER WEST HALF. SOUNDINGS
MAINTAIN LOOK OF ELEVATED NARROW DGZ AND TEMPS WARMER THAN -8C
BLO...SO LOW SLR/S...PROBABLY AROUND 10:1. BY LATE TUESDAY
AFTN...EXPECT TOTAL SNOWFALL OVER 4 INCHES OVER MOST OF THE WEST
HALF OF THE CWA...MAYBE PUSHING TOWARD 6 INCHES OVER INTERIOR WEST.
CLOSER TO LK SUPERIOR OVR NCNTRL WHERE ENE WINDS PROVIDE FLOW OF
LAKE MODIFIED WARMING...EXPECT SNOW TOTALS TO BE HELD DOWN. CONTINUED
TO INCREASE POPS TO CATEGORICAL. IT WILL SNOW. ONLY THING THAT
TEMPERS CONFIDENCE ON ISSUING 3RD PERIOD ADVY IS INCONSISTENCIES IN
WHERE THE HIGHER QPF IS ON MODELS. WILL OPT FOR A SPECIAL WEATHER
STATEMENT AND LET DAYSHIFT GET SOME MORE DATA BEFORE MAKING FINAL
CALL ON HEADLINE.
BULK OF PRECIP WILL BE DONE BY WEDNESDAY EVENING. 00Z NAM WAS QUITE
EMPHATIC WITH DEFORMATION ZONE OF LINGERING SNOW OVER THE WEST CWA
BUT WAS NOT SUPPORTED IN ITS INTENSITY BY ANY OTHER GUIDANCE. 06Z
NAM IS NOT AS BULLISH. THOUGH SOME LGT SNOW COULD CONTINUE AS AN
AREA OF MID LEVEL FGEN/DEFORMATION WILL BE REINFORCED BY WEAK TROWAL.
EVEN THIS AREA OF SNOW SHOULD DIMINISH TO LGT SNOW/FLURRIES LATE ON
TUESDAY NIGHT. FARTHER EAST...SOUNDINGS SIGNAL POSSIBLE DRIZZLE OR
FREEZING DRIZZLE AND FOG AS MID-LEVEL DRYING LEAVES MOIST LOW-LEVELS
WITH TEMPS MAINLY WARMER THAN -7C. CARRIED SLIGHT CHANCE POPS FOR
RAIN/SNOW...BUT THIS MAY NEED TO BE CONVERTED TO DZ/FOG WITH LATER
FORECASTS.
MODELS CONTINUE TO HAVE FUN WITH THE CHRISTMAS EVE SYSTEM AFFECTING
THE GREAT LAKES. AFTER BACKING AWAY COMPLETELY 24 HR AGO...MOST OF
THE MODELS CAME BACK TO SHOWING A STRONG LOW LIFTING NORTHWARD OVER
THE CNTRL GREAT LAKES WITH THE RUNS ON SUNDAY. THAT IS WHERE WE
REMAIN FOR MOST PART NOW...WITH ALL BUT THE GEM-GLOBAL AND PARALLEL
GFS INDICATING THIS SYSTEM MISSES UPR MICHIGAN. KEPT SMALL CHANCES
IN OVER FAR EAST...VCNTY OF LUCE COUNTY...BUT OTHERWISE KEPT THE CWA
VOID OF ANY POPS FM THE SYSTEM. HAVE SOME SMALL CHANCE POPS OVER THE
WEST HALF ON CHRISTMAS EVE DAY...BUT THIS IS GENERALLY DUE TO SOME
SIMBLANCE OF THE LINGERING DEFORMATION AREA FM THE TUESDAY SYSTEM
THAT WILL ONLY BE SLOWLY UNRAVELING OVER THE EAST PART OF CWA ON
WEDNESDAY.
INTO CHRISTMAS AND BEYOND...RAN WITH CONSENSUS. COULD SEE SOME LGT
LK EFFECT FOR WNW-NW FLOW AREAS ON CHRISTMAS THOUGH H85 TEMPS NEAR
-10C ARE ONLY MARGINAL FOR PURE LES. WOULD NEED SOME ADDITIONAL
LARGE SCALE SUPPORT TO RESULT IN BETTER CHANCES OF LES VIA LAKE
ENHANCEMENT. AS LONG AS THE CNTRL GREAT LAKES LOW DOES NOT COME ANY
FARTHER WEST...WILL NOT BE VERY WINDY EITHER. HIGHS ON CHRISTMAS TOP
OUT ABOVE NORMAL...WITH LOW TO MID 30S EXPECTED. AS ALLUDED TO
EARLIER...ANOTHER CLIPPER TYPE SYSTEM COULD SPREAD SOME LGT SNOW TO
THE AREA ON FRIDAY. UNCERTAINTY AND CONSISTENCY IN THAT IDEA BOTH
ARE HIGH...SO CHANCE POPS UNTIL IT GETS MORE REFINED. AT THE MOST
COULD SEE MODERATE SNOW AMOUNTS. IDEA OF COLDER WEATHER WITH LK
EFFECT STILL ON TRACK FOR THE WEEKEND. MOISTURE IS A QUESTION THOUGH
SO EVEN THOUGH H85 TEMPS FALL DOWN BLO -15C ON SUNDAY...EVEN
MODERATE LK EFFECT SNOW IS NOT A DONE DEAL YET. COOLER TEMPS WILL BE
NOTICABLE THOUGH AFTER THE RATHER MILD CHRISTMAS WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1257 PM EST MON DEC 22 2014
MVFR TO IFR CEILINGS COVER MUCH OF UPPER MICHIGAN AS MOIST
SOUTHEASTERLY FLOW IS OCCURRING AHEAD OF A LOW PRESSURE SYSTEM IN
EASTERN SOUTH DAKOTA. AT KSAW...CEILINGS AND VISIBILITES ARE LOWER
DUE TO THE FAVORABLE UPSLOPE WIND DIRECTION. EXPECT THESE LOWER
CLOUDS TO REMAIN INTO THE EVENING HOURS...ALTHOUGH THEY MAY RAISE
SOME TOWARDS LATE AFTERNOON AS DRIER AIR FROM LOWER MICHIGAN
ATTEMPTS TO WORK INTO THE AREA. HAD THE GREATEST CONFIDENCE AT
CONDITIONS STAYING AT OR BELOW MVFR...BUT THERE COULD BE A PERIOD OF
VFR CEILINGS IF THE DRIER AIR CAN WORK INTO THE AREA.
SNOW WILL WORK INTO THE AREA OVERNIGHT INTO TUESDAY AS THE LOW
PRESSURE SYSTEM LIFTS NORTHEAST TOWARDS THE AREA. THERE WILL LIKELY
BE TWO SURGES OF PRECIPITATION WITH THIS LOW...THE FIRST COMING
DURING THE OVERNIGHT HOURS AND THE SECOND ARRIVING BY LATE MORNING
OR EARLY AFTERNOON. THE SECOND WAVE WILL PRODUCE THE STRONGEST SNOW
AND DID DROP KSAW DOWN TO LIFR VISIBILITES TO ACCOUNT FOR THAT
MOVING THROUGH LATE IN THE TAF PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 425 AM EST MON DEC 22 2014
SSE WINDS UP TO 25-30 KTS OVER MAINLY THE E HALF OF LK SUPERIOR WILL
PERSIST THRU TODAY BUT THEN BACK TO THE E TONIGHT AND THEN THE NE ON
TUE AS A LO PRES SYSTEM MOVES NE FROM THE CENTRAL PLAINS TO OVER
LAKE MICHIGAN BY LATE IN THE DAY ON TUE. SINCE THIS LO WILL SLOWLY
WEAKEN AS IT MOVES TO THE NE...THE NE WINDS WILL FALL UNDER 20 KTS
ON TUE NIGHT. SINCE THE LATEST GUIDANCE INDICATES THE NEXT DEEPER LO
WILL TRACK N FARTHER TO THE E ON WED...A WEAKER PRES GRADIENT/N WIND
UNDER 20 KTS WILL DOMINATE ON WED. YET ANOTHER LO PRES MAY MOVE NE
FROM THE CENTRAL PLAINS LATE IN THE WEEK. AT THIS TIME...WINDS UNDER
25 KTS ARE EXPECTED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...JLA
AVIATION...SRF
MARINE...KC
AREA FORECAST DISCUSSION
NWS BILLINGS MT
358 PM MST MON DEC 22 2014
.SHORT TERM...VALID FOR TUE AND WED...
UNSETTLED NORTHWEST FLOW OVER THE REGION WITH A BETTER AREA OF
WRAP AROUND SNOWFALL IN SOUTHEAST MONTANA WHERE ACCUMULATIONS OF
1/2 INCH TO AN INCH HAVE BEEN REPORTED WITH OBSERVATIONS SHOWING
20 TO 30 MPH WINDS. RADARS SHOW SNOW STILL MOVING INTO THE AREA
WITH RAP FORECASTING ADDITIONAL SNOWFALL THROUGH THE EVENING
HOURS. WILL KEEP THE ADVISORY FOR FALLON AND CARTER COUNTIES BUT
ECHOS ARE DECREASING FOR CUSTER AND POWDER RIVER COUNTIES SO WILL
CANCEL THE ADVISORIES FOR THOSE AREAS.
TUESDAY IS A QUIETER WEATHER DAY ACROSS THE REGION AS HEIGHTS
BUILD AND THE AIRMASS DRIES OUT. A SERIES OF DISTURBANCES MOVING
THROUGH BC BEGIN A ROUND OF LEESIDE TROUGHING LATE IN THE DAY WITH
WILL PROMOTE SOME MIXING BUT TEMPERATURES WILL NOT REBOUND PAST
THE 30S. LEESIDE TROUGHING STRENGTHENS TUESDAY NIGHT WHICH SETS UP
GAP FLOW WINDS FOR LIVINGSTON AND NYE AREAS. GUIDANCE SHOWS WIND
ADVISORY CRITERIA WINDS DEVELOPING AFTER MIDNIGHT SO WILL NOT
ISSUE A HIGHLIGHT YET BUT WILL BEGIN MESSAGING ABOUT A PERIOD OF
STRONG WINDS ALONG I90 LATE TUESDAY INTO WEDNESDAY.
ENERGY CONTINUES TO STREAM ACROSS ALBERTA AND BC WEDNESDAY WITH A
STRONGER WAVE MOVING INTO WASHINGTON AND OREGON DURING THE DAY.
THIS MAINTAINS THE FAVORABLE PRESSURE GRADIENTS AND INCREASES
MIXING SO TEMPERATURES WILL BE WARMER BY A FEW DEGREES. APPROACH
OF THE DISTURBANCE WEDNESDAY NIGHT ALLOWS A COLD FRONT TO MOVE
NORTH TO SOUTH THROUGH MONTANA WITH THE HEIGHTS FALLING. THE
ALIGNMENT OF THE FRONT MOVING INTO SOUTHERN MONTANA AFTER MIDNIGHT
AND THE DYNAMICS OF THE UPSTREAM WAVE INCREASING THE MOISTURE IN
THE AIRMASS WILL ALLOW FOR THE DEVELOPMENT OF SNOW AND
FRONTOGENESIS. EXPECT SNOW TO BEGIN FOR AREAS AROUND JUDITH GAP
AND HARLOWTON WEDNESDAY EVENING AND SPREADING SOUTH OVERNIGHT. BY
LATE WEDNESDAY NIGHT EXPECT MOST AREAS TO SEE SOME SNOW FALLING
WITH THE EXCEPTION OF SHERIDAN COUNTY WHICH MAY STILL BE WAITING A
FEW HOURS FOR IT TO DEVELOP.
THE FAVORABLE INGREDIENTS LATE WEDNESDAY NIGHT SHOULD YIELD 1 TO 3
INCHES OF SNOWFALL BY DAYBREAK WITH SNOW CONTINUING WITH THE
HIGHER AMOUNTS EXPECTED WEST OF BILLINGS...SOUTHEAST MONTANA
ACCUMULATIONS WILL BE CLOSER TO AN INCH. WINDS BECOMING UPSLOPE
WILL HELP SNOWFALL RATES INCREASE IN THE LATE NIGHT HOURS WITH A
GOOD RATE OF SNOWFALL EXPECTED AT THE VERY END OF THE SHORT TERM
FORECAST PERIOD. BILLINGS HAS NOT HAD AN INCH OR BETTER OF
SNOWFALL ON CHRISTMAS DAY SINCE 1988 AND SHERIDAN SINCE 1996 SO
THIS WILL BE A NOTABLE EVENT. THE RECORD SNOWFALL FOR BILLINGS FOR
CHRISTMAS DAY OF 4.5 INCHES COULD BE THREATENED. BORSUM
.LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
THE MAIN FOCUS IN THE EXTENDED REMAINS THE SNOW ON CHRISTMAS DAY.
THE LATEST RUNS OF THE GFS AND ECMWF HAVE COME INTO BETTER
AGREEMENT WITH EACH OTHER. THE 12Z NAM IS MAYBE SLIGHTLY FASTER
THAN THE GFS/ECMWF...BUT THE GEM IS THE MAIN OUTLIER...MAINTAINING THE
FASTER SOLUTION. HAVE TRENDED THE SNOW AMOUNTS UP
SLIGHTLY...GENERALLY 3 TO 5 ACROSS MUCH OF THE PLAINS...WITH
AMOUNTS INCREASING TO WEST INTO THE MOUNTAINS. WINDS WILL BE OUT
OF THE NORTH FOR MUCH OF CHRISTMAS DAY...WHICH SETS UP A GOD
UPSLOPE FLOW EVENT FOR THE MOUNTAINS. BUFKIT SOUNDINGS ARE SHOWING
A VERY MOIST DENDRIDIC GROWTH LAYER THROUGH MUCH OF THE DAY...SO
EXPECTING GOOD SNOWFALL RATES OUT OF THIS SYSTEM.
GIVEN THAT THE AREA WILL BE UNDER CLOUD COVER WITH FALLING
SNOW...HAVE KEPT TEMPERATURES CHRISTMAS DAY A LITTLE COOLER THAN
GUIDANCE. THROUGHOUT THE EXTENDED...TEMPERATURES WILL REMAIN
COLD...WITH HIGHS GENERALLY IN THE 20S TO LOWER 30S...AND LOWS
DROPPING INTO THE TEENS.
FRIDAY THINGS SHOULD DRY OUT AS THE SYSTEM MOVES INTO THE CENTRAL
PLAINS. SATURDAY SHOULD BE ANOTHER QUIET DAY ACROSS THE
AREA...BEFORE WE SEE THE NEXT TROUGH MOVE INTO THE AREA WITH
ANOTHER ROUND OF SNOW SUNDAY. THE GFS IS A BIT FASTER WITH THIS
SECOND SYSTEM...BUT AT THIS POINT AM GOING WITH A BLEND OF THE
MODELS GIVEN THAT THIS IS AT THE END OF THE FORECAST PERIOD.
REIMER
&&
.AVIATION...
LIGHT SNOW SHOWERS WILL CONTINUE ACROSS THE AREA THROUGH
MIDNIGHT...WITH THE HEAVIER SNOWFALL FROM MILES CITY TO BROADUS
AND EAST. GENERALLY VFR CONDITIONS WILL PREVAIL. SOME SNOW SHOWERS
WILL PRODUCE SOME BRIEF LOCALIZED MVFR CONDITIONS...AND CONTINUE
TO OBSCURE THE MOUNTAINS. WINDS WILL REMAIN GUSTY THROUGH MID
EVENING. REIMER
&&
.PRELIMINARY POINT TEMP/POPS...
TUE WED THU FRI SAT SUN MON
-----------------------------------------------------------
BIL 025/039 026/042 027/028 012/025 012/029 018/027 008/019
20/N 01/B 78/J 51/B 11/B 23/J 32/J
LVM 014/034 023/042 025/026 012/028 011/031 018/030 009/023
20/N 02/W +9/J 62/J 11/N 23/J 32/J
HDN 022/037 019/042 026/027 010/025 010/028 015/027 008/019
30/B 11/B 58/J 52/J 11/B 23/J 32/J
MLS 021/035 019/042 026/027 013/023 009/028 013/024 006/016
41/B 11/E 66/J 41/E 11/B 22/J 22/J
4BQ 024/034 017/042 025/026 014/024 007/027 013/027 007/019
52/S 11/B 47/J 42/J 11/B 13/J 32/J
BHK 024/029 015/038 024/025 008/019 007/025 009/021 003/013
72/S 11/B 45/J 41/E 11/B 22/J 22/J
SHR 025/036 018/042 025/026 012/026 008/031 013/029 010/022
41/B 01/B 48/J 52/J 11/B 13/J 32/J
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY IN EFFECT UNTIL 5 AM MST TUESDAY FOR
ZONES 33-37.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
307 PM EST MON DEC 22 2014
.SYNOPSIS...
MOISTURE WILL OVERRUN A COOL SURFACE AIR MASS THE REMAINDER OF THE
DAY LEADING TO PERIODS OF LIGHT RAIN. THIS AIR MASS LIFTS OUT ON
TUESDAY CLEARING THE PATH FOR WARMER TEMPERATURES AND EVEN MORE
MOISTURE. A COLD FRONT MAY ADD SOME THUNDER WEDNESDAY AND WEDNESDAY
NIGHT. DRY AND SEASONABLE WEATHER RETURNS FOR CHRISTMAS AND THE
DAYS THAT FOLLOW.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
AS OF 3 PM MONDAY...THE COASTAL FRONT IS STILL LOCK IN ITS LOCATION
OFF THE COAST AND EXPECT IT TO REMAIN OFF THE COAST THROUGHOUT THE
OVERNIGHT PERIOD. OF THE 2 U.S. DETERMINISTIC MODELS THE NAM APPEARS
TO BE HANDLING THIS FEATURE THE BEST BY KEEPING OFF THE COAST
LONGER. THE GFS CONTINUES WITH IT INSTANCE TO BRING THE BOUNDARY
CLOSER TO THE COAST OVERNIGHT. WITH PAST HISTORY OF MODELS AND IT
POOR HANDLING OF COASTAL FRONTS WILL SIDE WITH THE SLOWER NAM MODEL.
THE LATEST HRRR MODEL...16 UTC...IS DEPICTING TWO WAVE PASSING
ACROSS THE FORECAST AREA THROUGH 06 UTC. ONE FOR THIS AFTERNOON AND
A SECOND BEFORE MIDNIGHT. THE BEST CHANCES APPEAR IN THE EASTERN
HALF OF THE FORECAST AREA.
WITH THE COLD AIR DAMMING IN PLACE DO NOT EXPECT TEMPERATURE TO
BUDGE OVERNIGHT WITH LOW CLOUDS AND A LIGHT NORTH WINDS.
TEMPERATURES ARE EXPECTED TO RANGE BETWEEN 42 AND 45 DEGREES.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...SHORT TERM WILL BE QUITE ACTIVE WITH A
COMPLEX STORM SYSTEM AFFECTING THE EASTERN CONUS. PERIOD BEGINS
WITH HIGH PRESSURE RIDGING DOWN THE COAST AND FRONT STALLED
OFFSHORE. AS IS TYPICAL THE GUIDANCE WANTS TO MOVE THE FRONT
ONSHORE EARLY TUE...BUT THIS PROBABLY WONT HAPPEN SAVE FOR THE
COAST UNTIL LATE IN THE DAY TUE OR EVEN TUE EVENING. THE RESULT
WILL BE CONTINUATION OF LIGHT PATCHY RAIN ALONG WITH POTENTIAL FOR
SOME EMBEDDED ELEVATED CONVECTION. THE FRONT AND ITS LOCATION ON
TUE WILL DETERMINE HIGH TEMPERATURE GRADIENT...WHICH IS LIKELY TO
BE SIGNIFICANT. ALONG THE COAST MID TO UPPER 60S IS POSSIBLE WHILE
WEST OF I-95 HIGHS MAY STRUGGLE TO REACH 50.
COASTAL FRONT PUSHES NORTHWEST OF THE AREA TUE NIGHT WITH STRONG
WARM ADVECTION AND IMPRESSIVE LOW LEVEL JETTING IN THE AREA.
FORECAST SOUNDINGS SHOW 45 KT DEVELOPING BY WED MORNING WHICH WILL
KEEP LOWS ABOVE TO WELL ABOVE CLIMO. INLAND AREAS MAY END UP WITH
TUE HIGHS AND TUE NIGHT LOWS BEING THE SAME OR WITHIN A DEGREE OF
EACH OTHER. FORECAST SOUNDINGS SHOW SOME WEAK INSTABILITY ABOVE
900MB ALONG WITH PVA AHEAD OF SHORTWAVES EJECTED NORTHEAST FROM THE
BASE OF THE 5H TROUGH. ALTHOUGH HARD TO PIN DOWN A FAVORED
LOCATION/TIME TUE NIGHT SHOULD BE FAIRLY ACTIVE AND WILL MAINTAIN
INHERITED CATEGORICAL POP. ALTHOUGH THERE WILL BE ELEVATED
INSTABILITY AND IMPRESSIVE JETTING DO NOT THINK DAMAGING WINDS WILL
BE AN ISSUE. THE BOUNDARY LAYER IS QUITE STABLE SO WHILE SURFACE
WINDS WILL BE GUSTY DUE TO THE ENHANCED GRADIENT DO NOT FORESEE
SIGNIFICANT SEVERE THREAT.
IMPRESSIVE WARM ADVECTION CONTINUES WED AHEAD OF THE APPROACHING
COLD FRONT. HIGHS WILL CLIMB INTO THE 70S IN A LOT OF AREAS DESPITE
CLOUD COVER. ONCE AGAIN THERE WILL BE STRONG LOW LEVEL JETTING AND
AN ABUNDANCE OF SHEAR BUT INSTABILITY WILL BE LACKING. FORECAST
SOUNDINGS PEAK MLCAPE VALUES BETWEEN 100 AND 200 J/KG WED AFTERNOON
WITH LOW LEVEL LAPSE RATES MARGINAL AT BEST. CONTINUE TO EXPECT
WIDESPREAD PRECIP BUT NOT AS CONFIDENT ON POTENTIAL FOR STRONG TO
SEVERE STORMS. STORM MOTIONS WILL BE ON THE ORDER OF 35 KT AND WITH
POTENTIAL FOR SOME CONVECTION CANNOT RULE OUT SEVERE WEATHER BUT IT
SEEMS LIKE A LONG SHOT AT THIS POINT...HENCE SPC HAVING MOST OF THE
FORECAST AREA IN MARGINAL RISK FOR DAY 3. DO THINK RAIN COULD BE
HEAVY AT TIMES WITH PRECIPITABLE WATER VALUES IN FORECAST SOUNDINGS
AROUND 2 INCHES. WORTH NOTING 2 INCHES WOULD BE RIGHT AROUND THE
HIGHEST EVER RECORDED FOR LATE DEC.
COLD FRONT MOVES ACROSS THE FORECAST AREA LATE WED NIGHT BRINGING AN
END TO PRECIP. LATE ARRIVAL/PASSAGE OF FRONT WILL NECESSITATE
KEEPING HIGH POP IN THE WED NIGHT PERIOD THOUGH BASED ON LATEST
TIMING THINK PRECIP WILL BE OVER IN MOST AREAS AROUND MIDNIGHT. THE
EXCEPTION WOULD BE THE NC COAST WHERE PRECIP MAY LINGER A FEW HOURS
AFTER MIDNIGHT. MID LEVEL TROUGH AXIS REMAINS WEST OF THE AREA INTO
THU KEEPING WHAT COLD AIR IS PRESENT WELL TO THE WEST. FORECAST
SOUNDINGS SHOW LOW LEVEL DRY AIR SPREADING OVER THE REGION BUT
MOISTURE ALOFT WILL KEEP CLOUD COVER IN PLACE THROUGH THE END OF THE
PERIOD. CLOUD COVER AND DEEP WESTERLY FLOW WILL KEEP WED NIGHT LOWS
ABOVE TO WELL ABOVE CLIMO.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 3 PM MONDAY...SUNSHINE WILL MAKE A REAPPEARANCE FINALLY ON
CHRISTMAS DAY. THE MID TO UPPER TROUGH JUST ENTERING THE CAROLINAS
THURS MORNING WILL PUSH THE COLD FRONT FARTHER OFF SHORE THROUGH THE
DAY LEAVING A DEEP W-NW FLOW OF DRIER AND SOMEWHAT COOLER AIR.
DEWPOINT TEMPS WILL DROP THROUGH THE DAY WITH A 20 PLUS DEGREE DROP
FROM PREVIOUS DAY. PCP WATER VALUES WILL DROP LESS THAN A HALF INCH
BY NOON AS COLUMN DRIES OUT. OVERALL EXPECT CLEARING THROUGH THE
MORNING WITH INCREASING SUNSHINE...GUSTY WINDS AND SEASONABLE TEMPS
CLOSER TO 60.
HIGH PRESSURE WILL BUILD UP FROM THE GULF COAST OVER THE SOUTHEAST
THURS INTO FRI. GUSTY WESTERLY WINDS ON THURS WILL LIGHTEN UP
BECOMING NEAR CALM THURS NIGHT AS THE CENTER OF THE HIGH SETTLES
OVER THE CAROLINAS. THE CLEAR SKIES AND LIGHT WINDS SHOULD ALLOW FOR
SOME DECENT RADIATIONAL COOLING AND TEMPS DOWN IN THE 30S THURS
NIGHT. A RETURN FLOW WILL SET UP THROUGH FRI AS RIDGE OF HIGH
PRESSURE SHIFTS OFF SHORE. THIS SOUTHERLY FLOW WILL ALLOW FOR A
RETURN OF MOISTURE AND WARMER TEMPS HEADING INTO THE WEEKEND. SHOULD
SEE AN INCREASE IN CLOUDS THROUGH SATURDAY AHEAD OF COLD FRONT
REACHING INTO THE CAROLINAS BY SAT NIGHT. BEST CHC OF PCP WILL COME
SAT NIGHT AS THE FRONT MOVES THROUGH. THIS COLD FRONT SHOULD PUSH
SOUTH THROUGH SUNDAY BUT THE FLOW ALOFT WILL REMAIN SW AS RIDGE
HOLDS ON TO OUR SOUTHEAST. THEREFORE WILL END UP WITH LOW CLOUDS
HANGING ON THROUGH THE START OF NEXT WEEK. TEMPS UP IN THE 60S ON
SATURDAY WILL BE BACK DOWN IN THE 50S MOST PLACES SUN AND MON
ESPECIALLY IF LOW CLOUDS HANG AROUND.
&&
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
AS OF 18Z...CIGS REMAIN AOB 600-700 FEET EARLY THIS AFTERNOON. VSBYS
ARE VFR...BUT MVFR/IFR VSBYS ARE OCCURRING IN AREAS OF RAIN/BR AND
EMBEDDED SHOWERS MOVING NE MAINLY BETWEEN THE INLAND AND COASTAL
TERMINALS.
LITTLE IMPROVEMENT IS EXPECTED THIS AFTERNOON. KFLO/KLBT STAND THE
BEST CHANCE OF HAVING 700-900 FT CIGS/VFR VSBYS...BUT AN INCREASING
CHANCE OF RAIN WILL LIKELY DROP VSBYS AT TIMES TO MVFR THROUGH THIS
EVENING AT THOSE TERMINALS. EXPECT WORST CIGS/VSBYS AT THE COASTAL
TERMINALS THIS AFTERNOON AND EVENING WHERE PRECIPITATION IS MORE LIKELY.
THE PRECIPITATION ENDS THIS EVENING BUT A SATURATED LOW LEVEL AND
LOWERING LOW-LEVEL INVERSION SUGGEST CIGS/VSBYS APPROACHING 200 /
1/2 AT THE COASTAL TERMINALS. KFLO/KLBT SHOULD HAVE THE BETTER
FLIGHT CONDITIONS BUT STILL AOB 600/2.
MVFR CIGS MAY DEVELOP AT KCRE/KMYR LATE IN THE TAF PERIOD AS A WARM
FRONT APPROACHES...BUT THE REMAINING TERMINALS STAND A GOOD CHANCE
OF REMAINING AOB 600/2.
EXTENDED OUTLOOK...LIFR/IFR CIGS TUE WITH INCREASING CHANCES OF
SHOWERS. MVFR COASTAL TERMINALS LATER IN THE DAY. WED EXPECT
SHOWERS/MVFR AND GUSTY WINDS AHEAD OF A COLD FRONT. GUSTY WEST WINDS
AND VFR THU BEHIND THE FRONT. VFR FRI/SAT.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 PM MONDAY...THE COASTAL FRONT REMAINS EAST OF FRYING PAN
SHOALS AND THE BEST NUMERICAL MODEL KEEPS THIS FRONT TO THE EAST OF
THE COASTAL WATERS. THIS WILL PROVIDE FOR A NORTH TO NORTHEAST WIND
OF LESS THAN 15 KNOTS AND SEAS SHOULD RUN IN THE 2 TO 4 FOOT RANGE
OVERNIGHT. AS LONG AS THE COASTAL FRONT STAYS TO THE EAST OF THE
WATERS THERE SHOULD BOT BE A THREAT OF SEA FOG.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 PM MONDAY...COASTAL FRONT ACROSS THE WATERS TUE WILL MOVE
ONSHORE LATER IN THE DAY. TIMING THE FRONT...AND THE RESULTING
STRONG SOUTHERLY FLOW IS ALWAYS DIFFICULT. GUIDANCE IS USUALLY TOO
FAST TO MOVE THE FRONT INTO THE COLDER AIR AND TUE APPEARS TO BE
NO DIFFERENT. THUS CONTINUE FOLLOWING THE TREND FROM PREVIOUS
FORECASTS WITH MOVEMENT OF THE FRONT DELAYED UNTIL TUE
AFTERNOON/EVENING. THIS WILL KEEP WINDS OVER THE NEARSHORE WATERS
LIGHT AND VARIABLE TOMORROW BEFORE SOUTHERLY FLOW INCREASES TUE
NIGHT. SPEEDS LATE TUE NIGHT AND WED WILL BE INTO THE 20 TO 25 KT
RANGE AT TIMES...BUILDING SEAS ACROSS ALL WATERS OVER 6 FT. SCA
WILL BE NEEDED PROBABLY STARTING CLOSE TO MIDNIGHT AND LASTING
THROUGH WED AND WED NIGHT. LATE IN THE PERIOD THE COLD FRONT MOVES
ACROSS THE WATERS WITH OFFSHORE FLOW DEVELOPING. COLD ADVECTION IS
LACKING BUT GRADIENT REMAINS TIGHT AND SPEEDS WILL REMAIN NEAR THE
20 TO 25 KT RANGE THROUGH THE END OF THE PERIOD.
LONG TERM /THURSDAY THROUGH FRIDAY/...
AS OF 3 PM MONDAY...COLD FRONT WILL SHIFT FARTHER OFF SHORE ON
THURS AS HIGH PRESSURE BUILDS UP FROM THE GULF COAST. GUSTY W-SW
WINDS EARLY THURS WILL VEER AROUND BECOMING WEST THROUGH THE DAY.
SEAS UP AROUND 5 TO 7 FT SHOULD FALL BELOW SCA THRESHOLDS BY THURS
AFTN WITH HIGHEST SEAS GETTING PUSHED FARTHER OFF SHORE IN STRONGER
W-NW FLOW BEHIND FRONT. WINDS WILL VEER FURTHER TO THE NW AND
LIGHTEN UP LATE THURS INTO FRI AS CENTER OF HIGH SHIFTS CLOSER
OVERHEAD. SEAS WILL BE DOWN TO 2 TO 4 FT BY THURS NIGHT AND DOWN TO
3 FT OR LESS THROUGH FRI AS HIGH PRESSURE MOVES OVERHEAD WITH MORE
VARIABLE WINDS EXPECTED.
HIGH PRESSURE WILL SHIFT FARTHER OFF SHORE ON SATURDAY WITH A RETURN
FLOW UNDER 15 KTS SETTING UP. A COLD FRONT WILL APPROACH SAT NIGHT
WITH WINDS VEERING AROUND AND INCREASING SLIGHTLY. THIS WILL PUSH
SEAS BACK UP CLOSER TO 3 TO 4 FT BY SUNDAY MORNING.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...DRH
SHORT TERM...III
LONG TERM...RGZ
AVIATION...MRR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1244 PM EST MON DEC 22 2014
.SYNOPSIS...
MOISTURE WILL OVERRUN A COOL SURFACE AIR MASS THE REMAINDER OF THE
DAY LEADING TO PERIODS OF LIGHT RAIN. THIS AIR MASS LIFTS OUT ON
TUESDAY CLEARING THE PATH FOR WARMER TEMPERATURES AND EVEN MORE
MOISTURE. A COLD FRONT MAY ADD SOME THUNDER WEDNESDAY AND WEDNESDAY
NIGHT. DRY AND SEASONABLE WEATHER RETURNS FOR CHRISTMAS AND THE
DAYS THAT FOLLOW.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1245 PM MONDAY...THE SURFACE LOW PRESSURE HAS SHIFTED
NORTHEASTWARD AND IS NOW OFF THE COAST BETWEEN NEAR CAPE
HATTERAS. THIS LOW HAS REINFORCED THE COOL NORTH WINDS AND IS
KEEPING THE COASTAL FRONT EAST OF FRYING PAN SHOALS. THE 12 UTC
NAM/GFS BOTH SHOWS THE COASTAL FRONT REMAINING OFF THE COAST UNTIL
TUESDAY MORNING.
ANOTHER WAVE OF IS MOVING UP THE COAST AND THE LATEST HRRR IS SHOWING
THE PRECIPITATION MAINLY TO THE SOUTH OF THE FORECAST AREA MOVING ACROSS
THIS AFTERNOON AND MAINLY EAST OF A KINGSTREE TO ELIZABETHTOWN
LINE. SO HIGH POPS TO THE EAST OF THE LINE AND CHANCE OF POPS TO
THE WEST.
WITH COLD AIR DAMMING IN PLACE AND CLOUDY SKIES ALL DAY EXPECTED
THE HIGHS WILL ONLY REACH 42-46 INLAND TO 47-49 AT THE BEACHES.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
AS OF 3 AM MONDAY...VERY ACTIVE WEATHER EXPECTED FOR THE DURATION OF
THE PERIOD. WEDGE WILL FINALLY BE BREAKING DOWN ON TUESDAY. THE
SPEED AT WHICH THIS OCCURS, WHICH IS NOTORIOUSLY DIFFICULT TO MODEL,
WILL MODULATE HIGH TEMPS. CURRENT FCST LEANS MORE ON THE SLOWER WRF
KEEPING MID 50S INLAND WHILE COASTAL LOCALES GET INTO MID/UPPER 60S.
DEEP SWRLY FLOW OF MOISTURE TO BRING PLENTY OF CLOUDS AND OCCASIONAL
RAIN FROM TIME TO TIME. PINNING DOWN WHERE RAIN WILL BE HEAVIEST IS
DIFFICULT AT THIS TIME. RAINFALL RATES TO INCREASE TUESDAY NIGHT
INTO WEDNESDAY AS STRONGER FLOW AND DYNAMICS SPREAD ACROSS THE
REGION WHILE COLD FRONT APPROACHES FROM THE NORTH AND WEST. THE
STRONGER RESULTING FLOW WILL BRING EVEN MILDER AIR INTO THE COASTAL
PLAIN AND HIGHS IN THE 70S APPEAR LIKELY DESPITE THE CLOUDS AND
RAIN. DESPITE THE WARMTH FORECAST SOUNDINGS SHOW SUCH POOR LAPSE
RATES THAT INSTABILITY IS REALLY GOING TO BE TOUGH TO COME BY, MAYBE
ENOUGH ENOUGH TO WORRY ABOUT HSLC SETUP. HAVE LEFT ISO THUNDER AS
SOME FAIRLY STRONG VERTICAL MOTION MAY IMPACT THE REGION LATE IN THE
PERIOD. WEDNESDAY NIGHT`S LOWS MAY BE VERY MILD LIKE TUESDAY NIGHT
SAVE FOR SOME COLD ADVECTION RELATED TO FROPA TOWARDS DAYBREAK
THURSDAY. SIMILARLY RAIN WILL BE RAPIDLY SHUTTING OFF FROM WEST TO
EAST LATE WEDNESDAY NIGHT...THE EXACT TIMING LIKELY NEEDING OF SOME
REFINEMENT IN FUTURE FORECASTS.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 3 AM MONDAY...CHRISTMAS AND THE FEW DAYS THAT FOLLOW WILL
FEATURE A RETURN OF SUNSHINE...NOT SEEN IN QUITE A WHILE. ALSO SINCE
THE UPPER WAVE DRIVING THE FRONT THROUGH NOW RETAINS A DEFINED
POSITIVE TILT THE COLD ADVECTION APPEARS QUITE TEMPERED AND THE
HOLIDAY WEEKEND NO LONGER SEEMS TO OFFER UP UNSEASONABLY COOL
TEMPERATURES IN FAVOR OF SEASONABLE WEATHER IF NOT A FEW DEGREES
ABOVE. MOISTURE MAY BE ON THE RISE BY SUNDAY AS A WEAK COLD FRONT
APPROACHES IN A STILL RATHER LOW AMPLITUDE PATTERN ALOFT.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AS OF 18Z...CIGS REMAIN AOB 600-700 FEET EARLY THIS AFTERNOON. VSBYS
ARE VFR...BUT MVFR/IFR VSBYS ARE OCCURRING IN AREAS OF RAIN/BR AND
EMBEDDED SHOWERS MOVING NE MAINLY BETWEEN THE INLAND AND COASTAL
TERMINALS.
LITTLE IMPROVEMENT IS EXPECTED THIS AFTERNOON. KFLO/KLBT STAND THE
BEST CHANCE OF HAVING 700-900 FT CIGS/VFR VSBYS...BUT AN INCREASING
CHANCE OF RAIN WILL LIKELY DROP VSBYS AT TIMES TO MVFR THROUGH THIS
EVENING AT THOSE TERMINALS. EXPECT WORST CIGS/VSBYS AT THE COASTAL
TERMINALS THIS AFTERNOON AND EVENING WHERE PRECIPITATION IS MORE LIKELY.
THE PRECIPITATION ENDS THIS EVENING BUT A SATURATED LOW LEVEL AND
LOWERING LOW-LEVEL INVERSION SUGGEST CIGS/VSBYS APPROACHING 200 /
1/2 AT THE COASTAL TERMINALS. KFLO/KLBT SHOULD HAVE THE BETTER
FLIGHT CONDITIONS BUT STILL AOB 600/2.
MVFR CIGS MAY DEVELOP AT KCRE/KMYR LATE IN THE TAF PERIOD AS A WARM
FRONT APPROACHES...BUT THE REMAINING TERMINALS STAND A GOOD CHANCE
OF REMAINING AOB 600/2.
EXTENDED OUTLOOK...LIFR/IFR CIGS TUE WITH INCREASING CHANCES OF
SHOWERS. MVFR COASTAL TERMINALS LATER IN THE DAY. WED EXPECT
SHOWERS/MVFR AND GUSTY WINDS AHEAD OF A COLD FRONT. GUSTY WEST WINDS
AND VFR THU BEHIND THE FRONT. VFR FRI/SAT.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1245 PM MONDAY...THE COASTAL FRONT REMAINS EAST OF FRYING
PAN SHOALS AND AND THE LOW THAT PAST JUST EAST OF THE WATERS HAS
SHIFTED NORTHEAST OF CAPE HATTERAS. THE WINDS ARE NORTHERLY AND
ARE AT 10 TO 15 KNOTS. THE SEAS HAVE DROPPED N A FOOT TO 4.5 FEET AT
41110 AND 5 FEET AT 41013. WINDS WILL REMAIN FROM THE NORTH AND AT
OR BELOW 15 KNOTS THROUGH THE NIGHT.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 3 AM MONDAY...TUESDAY CHARACTERIZED BY WEAKENING WEDGE OF HIGH
PRESSURE OVER LAND. THE SPEED AT WHICH THIS OCCURS IS ALWAYS A BIT
UNCERTAIN AND THIS WILL AFFECT HOW QUICKLY LOCAL WINDS VEER AND
INCREASE IN SPEED. HAVE OPTED FOR THE SLOWER MODEL SOLUTION WHICH
WILL KEEP THE MAIN DETERIORATION OF CONDITIONS OFF UNTIL TUESDAY
NIGHT. AT THIS TIME THE SSWRLY FLOW REALLY BECOMES ESTABLISHED IN A
STRENGTHENING STATE AS LOW LEVEL WIND FIELDS CRANK UP AND A COLD
FRONT AND STRONG UPPER TROUGH APPROACH. SMALL CRAFT ADVISORY
EXPECTED BY TUES NIGHT. WIND AND SEAS ONLY INCREASE FROM THERE AS
THE APPROACHING BOUNDARY TIGHTENS THE GRADIENT AND THE APPROACH OF
THE UPPER WAVE STRENGTHENS LOW LEVEL WIND FIELDS. FROPA EXPECTED
TOWARDS THE END OF THE PERIOD WITH AN ABRUPT WIND VEER.
LONG TERM /THURSDAY THROUGH FRIDAY/...
AS OF 3 AM MONDAY...THE LONG TERM STARTS OFF WITH SMALL CRAFT
ADVISORY FLAGS FLYING JUST FOLLOWING VIGOROUSLY DRIVEN COLD FRONT.
HOWEVER THE COLD SURGE ITSELF IS RATHER UNIMPRESSIVE AND WINDS AND
SEAS SHOULD BOTH DROP OFF RATHER NICELY AS THE DAY WEARS ON. TOUGH
TO RULE OUT A PERIOD OF SCEC THOUGH AS THE SHARP WIND SHIFT COULD
LEAD TO RATHER STEEP WAVE FACES EVEN AS THEIR OVERALL HEIGHT
DECREASES. FRIDAY BRINGS A LIGHT OFFSHORE FLOW AS HIGH PRESSURE
SLOWLY BUILDS IN FROM THE WEST.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...HAWKINS
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...MRR
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1221 PM CST MON DEC 22 2014
.UPDATE...
ISSUED AT 1221 PM CST MON DEC 22 2014
WINTER WEATHER CONTINUES WITH IMPACTS ON TRAVEL TODAY. MAIN
CHANGES WERE TO ISSUE A WINTER WEATHER ADVISORY FOR THE JAMES
RIVER VALLEY INTO FAR SOUTH CENTRAL NORTH DAKOTA FOR THE
ANTICIPATED TROWAL INDUCED SNOW BAND STARTING TO DEVELOP ACROSS
THE SOUTHEASTERN PART OF NORTH DAKOTA NOW. A PERIOD OF RAIN OR A
RAIN/SNOW MIX IS LIKELY FROM EASTERN PORTIONS OF FOSTER SOUTH
THROUGH LAMOURE AND DICKEY BEFORE BECOMING ALL SNOW LATER. WINTER
WEATHER ADVISORY NORTHEAST IN GOOD SHAPE...AND THE WINTER WEATHER
ADVISORY WEST ALSO GOOD FOR THIS UPDATE. DID ADD GRANT COUNTY
WHICH HAS BEEN RECEIVING SNOW FOR MUCH OF THE MORNING AND MAY GET
GRAZED WITH THE WRAP AROUND SNOW TONIGHT.
DENSE FOG ADVISORY WAS EXPIRED WITH THE ISSUANCE OF THE WSW.
UPDATE
ISSUED AT 1005 AM CST MON DEC 22 2014
ANOTHER COMPLEX WEATHER SCENARIO ACROSS THE NORTHERN PLAINS THIS
MORNING.
DEFORMATION ZONE WELL ESTABLISHED ACROSS WESTERN NORTH DAKOTA
CONTRIBUTING TO ACCUMULATING SNOWFALL AS EXPECTED. REGIONAL
SATELLITE IMAGERY DEPICTS THE AXIS OF DILATATION WELL...STRETCHED
FROM WESTERN/CENTRAL SOUTH DAKOTA BACK NORTH-NORTHWEST ACROSS
WESTERN NORTH DAKOTA INTO SOUTHERN SASKATCHEWAN. CURRENT WINTER
WEATHER ADVISORY IN GOOD SHAPE THERE.
MODELS YESTERDAY ACCURATELY PREDICTED THE UNSATURATED ATMOSPHERE
NOW IN PLACE ACROSS THE NORTHEASTERN QUARTER OF THE STATE.
WIDESPREAD FREEZING DRIZZLE HAS BEEN ONGOING AND CONTINUES THERE.
MY COUNTIES BORDERING THE DEVILS LAKE BASIN ARE ON THE EDGE OF MID
LEVEL CLOUDS/SATURATE AIR ALOFT TO THE WEST. WE MADE A FEW CALLS TO
THOSE LOCATIONS AND BASED ON THOSE REPORTS AND IN COLLABORATION
WITH WFO GRAND FORKS OPTED TO HOIST A WINTER WEATHER ADVISORY FOR
THE FREEZING DRIZZLE. ENDED AT 00Z AS MODELS SUGGEST WE SHOULD BE
WELL SATURATED THROUGH THE MID LEVELS BY LATE THIS AFTERNOON.
DENSE FOG ADVISORY WAS EXTENDED THROUGH 19Z WITH VIS STILL 1/4
MILE OR LESS MANY LOCATIONS. WILL REEVALUATE OVER THE NEXT 3 HOURS
IN CASE IT NEEDS TO BE RE EXTENDED...OR PORTIONS OF IT.
NEXT WEATHER HAZARD WILL BE SNOW DEVELOPMENT ACROSS THE JAMES
RIVER VALLEY AND OVER MY FAR SOUTH CENTRAL AS A TROWAL BECOMES
ESTABLISHED AND WRAPS OVER THE EASTERN DAKOTAS. A WINTER WEATHER
ADVISORY MAY BE NEEDED THERE IN THE NEAR FUTURE AND WILL MAKE THAT
DECISION BEFORE 3PM CST TODAY.
UPDATE ISSUED AT 655 AM CST MON DEC 22 2014
WITH THIS UPDATE ISSUED A DENSE FOG ADVISORY THROUGH 16 UTC FOR
SOUTH CENTRAL NORTH DAKOTA AND THE JAMES RIVER VALLEY GIVEN
CURRENT OBSERVATIONS AND WEBCAMS. ALSO HIGHLIGHTED THE FREEZING
DRIZZLE POTENTIAL FOR THESE AREAS AS WELL. WILL ISSUE AN SPS FOR
THE NORTH CENTRAL WHERE FOG IS NOT DENSE...BUT...PATCHY FREEZING
DRIZZLE IS ALSO POSSIBLE. IN REGARDS TO THE WINTER WEATHER
ADVISORY...ADDED DIVIDE AND WILLIAMS COUNTIES AS THE 06 UTC
NAM/GFS...00 UTC GEM AND 10-11 UTC RAP RUNS ALL HIGHLIGHT THIS
AREA FOR THREE TO FOUR INCHES OF SNOW TODAY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 412 AM CST MON DEC 22 2014
FORECAST HIGHLIGHTS IN THE SHORT TERM WILL INCLUDE FOG AND THE
POSSIBILITY OF FREEZING DRIZZLE IN CENTRAL NORTH DAKOTA THIS
MORNING. THEN ATTENTION TURNS TO DEVELOPING SNOW IN THE WEST
SPREADING INTO CENTRAL NORTH DAKOTA...WITH ACCUMULATING SNOW AND
SOME BLOWING SNOW.
CURRENTLY...A SURFACE LOW WAS CENTERED OVER WESTERN NORTH DAKOTA -
OVER WESTERN LAKE SAKAKAWEA...WITH A TROUGH EXTENDING SOUTHEASTWARD
INTO CENTRAL SOUTH DAKOTA. LOW STRATUS CLOUDS BELOW 500 FEET AND FOG
WITH VISIBILITIES FROM 1/2 MILE TO 5 MILES. AT UPPER LEVELS A BROAD
TROUGH WAS IN PLACE ACROSS THE FRONT RANGE AND PLAINS STATES. WATER
VAPOR SAT LOOP INDICATES A SMALL CIRCULATION ACROSS SOUTHWESTERN
NORTH DAKOTA AND INTO WESTERN SOUTH DAKOTA...INDICATIVE OF EMBEDDED
SHORTWAVE AND A MINOR UPPER LOW. REGIONAL RADAR MOSAIC LOOPS
INDICATE INCREASING COVERAGE IN LIGHT RETURNS FROM NORTHEASTERN
MONTANA ACROSS WESTERN NORTH DAKOTA INTO CENTRAL/WESTERN SOUTH
DAKOTA. DICKINSON REPORTED "UNKNOWN PRECIPITATION" THIS PAST
HOUR...WHICH COULD BE RAIN CHANGING TO SNOW.
THE UPPER LEVEL LOW/TROUGH IS EXPECTED TO CONTINUE DEVELOPING A
CLOSED LOW OVER SOUTH DAKOTA THIS AFTERNOON. THIS WILL INDUCE THE
SURFACE LOW CENTER TO DEVELOP SOUTH INTO CENTRAL/EASTERN SOUTH
DAKOTA TODAY. THUS THE MAIN ENERGY...UPPER LEVEL CIRCULATION AND
LIFT...AND BEST SURFACE CONVERGENCE WILL DEVELOP SOUTH OF THE ND/SD
BORDER. SINCE THE EVOLUTION OF THIS SYSTEM HAS SLOWED AND EXPECTED
PRECIPITATION HAS BEEN LATER THAN PREVIOUSLY FORECAST...COMBINED
WITH THE SOUTHWARD MOVEMENT OF THE STORM SYSTEM...WE DO NOT EXPECT
QUITE AS MUCH SNOWFALL ACROSS WESTERN AND CENTRAL NORTH DAKOTA.
INSTEAD THE BULK OF THE SNOW IS EXPECTED IN SOUTH DAKOTA AND INTO
SOUTHERN MINNESOTA.
EXPECT DEVELOPING SNOW OVER WESTERN NORTH DAKOTA THIS
MORNING...SPREADING INTO CENTRAL NORTH DAKOTA LATER THIS
MORNING...AND CONTINUING MAINLY ACROSS THE SOUTHERN HALF OF NORTH
DAKOTA TONIGHT AND INTO TUESDAY.
TOTAL SNOWFALL EXPECTED TODAY THROUGH TUESDAY: NORTHERN NORTH DAKOTA
SNOWFALL TOTALS SHOULD RANGE FROM 1/2 INCH IN THE TURTLE MOUNTAINS
TO AROUND 2 INCHES AT WILLISTON. ACROSS SOUTHERN NORTH DAKOTA
SNOWFALL TOTALS OF 2 TO 2 1/2 INCHES ALONG AND SOUTH OF A LINE FROM
WATFORD CITY TO HARVEY AND CARRINGTON.
NORTHWEST WINDS OF 15 TO 30 MPH ARE EXPECTED OVER SOUTHWESTERN NORTH
DAKOTA TODAY AND TONIGHT. THIS WILL CREATE AREAS OF BLOWING AND
DRIFTING SNOW THAT WOULD IMPACT HOLIDAY TRAVEL. A WINTER WEATHER
ADVISORY HAD BEEN ISSUED FOR THIS AREA...IN EFFECT TODAY AND
TONIGHT. WILL KEEP THIS ADVISORY GOING BECAUSE OF THE BLOWING SNOW
HAZARD REDUCING VISIBILITIES...DESPITE THE LOWER SNOW AMOUNTS
EXPECTED. WILL ALSO KEEP A SPECIAL WEATHER STATEMENT RUNNING FOR THE
REST OF WESTERN AND CENTRAL NORTH DAKOTA TO HIGHLIGHT THE EXPECTED
SNOW FOR HOLIDAY TRAVEL.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 352 AM CST MON DEC 22 2014
DIMINISHING SNOW ON TUESDAY AND LIGHT SNOW CHRISTMAS DAY HIGHLIGHT
THE EXTENDED FORECAST.
TO BEGIN THE PERIOD...THE 00 UTC DETERMINISTIC AND ENSEMBLE SUITES
ARE IN AGREEMENT ON WRAP AROUND LIGHT SNOWFALL ENDING FROM WEST
TO EAST THROUGH TUESDAY ACROSS NORTH DAKOTA AS THE UPPER LEVEL LOW
SLOWLY FILLS AND PROPAGATES INTO THE GREAT LAKES. TRAVEL ON
WEDNESDAY ACROSS THE NORTHERN PLAINS LOOKS GOOD. HOWEVER...FOR
CHRISTMAS DAY THURSDAY THE MODELS BEGIN TO DIVERGE ON THEIR TIMING
AND EVOLUTION OF THE PACIFIC NORTHWEST WAVE AS IT PROPAGATES
ACROSS THE ROCKIES...WITH AN ASSOCIATED SNOW BAND IN ISENTROPIC
LIFT POSSIBLE ACROSS THE DAKOTAS. WHILE UNCERTAINTY
REMAINS...SOME TRAVEL IMPACTS ARE POSSIBLE FOR CHRISTMAS DAY
ACROSS WESTERN AND CENTRAL NORTH DAKOTA. THEREAFTER...TEMPERATURES
TREND BELOW NORMAL A AS ABROAD LONG WAVE TROUGH ENVELOPS THE CONUS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1221 PM CST MON DEC 22 2014
HAZARDS TO AVIATION TODAY INVOLVE LOW IFR CONDITIONS WITH PATCHY
FREEZING DRIZZLE CENTRAL AND EAST TODAY...SNOW WEST...AND
DEVELOPING SNOW SOUTH CENTRAL AND SOUTHEAST TODAY INTO TONIGHT.
MVFR/IFR CONDITIONS IN SNOW AND BLOWING SNOW AT KISN-KDIK WITH
GUSTS TO 30 KTS AND VSBYS LESS THAN 1 MILE AT TIMES IN BLOWING
SNOW. MVFR/IFR IN SNOW WEST SPREADING EAST. WIDESPREAD IFR
CONDITIONS WILL PERSIST THROUGH TUESDAY MORNING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 6 PM CST TUESDAY FOR NDZ025-036-
037-045>048-050-051.
WINTER WEATHER ADVISORY UNTIL 6 AM CST /5 AM MST/ TUESDAY FOR
NDZ001-009-017-031>033-040>044.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR NDZ005-
013-023.
&&
$$
UPDATE...NH
SHORT TERM...JV
LONG TERM...AYD
AVIATION...AYD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1259 PM EST MON DEC 22 2014
.SYNOPSIS...
HIGH PRESSURE WILL RETREAT NORTHEAST INTO THE CANADIAN MARITIMES
EARLY THIS WEEK...AS A WEAK LOW PRESSURE SYSTEM LIFTS UP THE MID
ATLANTIC COAST. AN INTENSIFYING STORM SYSTEM WILL TRACK WEST OF
PENNSYLVANIA WEDNESDAY NIGHT...PUSHING A COLD FRONT THROUGH
THE STATE. ANOTHER LESS POTENT COLD FRONT IS LIKELY TO IMPACT THE
REGION BY NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MOISTURE SLOWLY INCREASING NORTH OF THE MASON DIXON LINE AS
MARITIME INFLUENCE INCREASES ACROSS SOUTHERN AND EASTERN PA. AT 1
PM...FZDZ/DZ IS NEARING THE KHGR AREA WITH SFC TEMPS THERE AT 34F
(TD 25F). BLEND OF THESE TRENDS PLUS THE LATEST HI RES HRRR AND
4KM HRW ARW SAYS POCKETS OF FZDZ AND FZRA ARE POSSIBLE FROM EARLY
AFTERNOON ONWARD LIFTING NORTH OF THE MD BORDER AND COVERING MUCH
OF THE SOUTH CENTRAL MOUNTAINS AFT 20Z. BEST ICING CHANCES ARE LATE
THIS AFTERNOON IN THESE AREAS...LIFTING NORTHWARD INTO THE
LAURELS AND NORTHERN PARTS OF THE SOUTH CENTRAL MOUNTAINS BEFORE
DARK.
FZRA ADVISORIES IN EFFECT FOR THE LAURELS AND SOUTH CENTRAL
MOUNTAINS...ALTHOUGH WESTERN PORTIONS OF THE LAURELS MAY BE LEFT
OUT OF THE PRECIP FOR SEVERAL HOURS (UNTIL WELL PAST DARK).
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
MOIST SERLY FLOW OFF THE ATLANTIC AND ASSOC OROGRAPHIC FORCING OF
SHALLOW MOISTURE LYR WILL LIKELY PRODUCE PATCHY LGT RAIN/DRIZZLE
TONIGHT AND TUESDAY. BEST CHC OF MEASURABLE PRECIP SHOULD COME
BTWN 00Z-06Z THIS EVENING WITH BENEFIT OF LG SCALE FORCING AHEAD
OF MID LVL SHORTWAVE. SFC TEMP FIELDS OF BOTH OPER AND ENSEMBLE
DATA SUGGEST THERE COULD BE ICING CONCERNS OVER THE HIGHER TERRAIN
OF CENTRAL PA. HOWEVER...TEMPS WILL BE VERY MARGINAL WITH ICING
MOST LIKELY ON THE RIDGETOPS. ALSO...NOT ENTIRELY SURE MEASURABLE
PRECIP WILL EVEN REACH FAR ENOUGH WEST TO CREATE A CONCERN. WILL
THEREFORE CONTINUE TO MENTION THREAT OF ICY ROADS IN THE HWO AND
AWAIT 12Z GUIDANCE TO GET A BETTER HANDLE ON THIS EVENT.
ANY ICING THREAT SHOULD END BY DAYLIGHT TUESDAY...WHEN ALL PLUME
MEMBERS RISE ABV FREEZING. RAINFALL AMTS TUESDAY SHOULD BE VERY
LIGHT...WITH SHALLOW MOISTURE IN MDL SOUNDINGS IMPLYING OCNL
DRIZZLE RATHER THAN RAIN.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
THE MOST SIGNIFICANT FORECAST ISSUE IN THE LONG TERM REMAINS THE
EVOLUTION OF DEEP TROUGH AND ASSOC SFC LOW TRACKING WEST OF PA
WED/WED NITE. STRONG SOUTHERLY FLOW AHEAD OF THIS SYSTEM SHOULD SCOUR
OUT LINGERING SHALLOW COLD AIR EAST OF THE APPALACHIANS. LOW-LEVEL
TEMPERATURE AND MOISTURE FIELDS RISE WELL ABOVE THEIR SEASONAL
VALUES...IMPLYING IT WILL BE A BALMY CHRISTMAS EVE FOR ALL.
ALL MED RANGE GUIDANCE TIMES THE TRAILING COLD FRONT THRU CENTRAL
PA WED NITE. A STRONG SOUTHERLY LL JET AND ASSOC PWAT ANOMALIES
ABOUT +3 SIGMA ABOVE NORMAL ARE PROGGED BY GEFS TO PASS THRU THE
AREA IN ADVANCE OF THE FRONT WED NITE. THIS STRONG SOUTHERLY
FLOW...HIGH PRECIPITABLE WATER AND SHARP CDFRONT ALL IMPLY A
FRONTAL RAIN EVENT WITH PERHAPS SOME RARE LATE DECEMBER (ELEVATED)
CONVECTION. HAVE ADDED CHC OF THUNDER BASED ON EXPECTED STRONG LG
SCALE FORCING IN ADVANCE OF UPPER TROF AND PRESENCE OF SOME MEAGER
MDL CAPES.
INTENSIFYING SFC LOW PASSING NORTH OF PA IS A FAVORABLE PATTERN
FOR STRONG WINDS ACROSS CENTRAL PA DURING THE COLD SEASON...SO STILL
MONITORING THE POTENTIAL OF STRONG WINDS COINCIDENT AND FOLLOWING
PASSAGE OF CDFRONT LATE WED NITE AND THURSDAY. WILL MENTION
POTENTIAL IN HWO.
COLDER AIR WORKING IN BEHIND COLD FRONT WILL LIKELY PRODUCE
OROGRAPHIC SNOW SHOWERS ACROSS THE ALLEGHENY PLATEAU ON CHRISTMAS
DAY. HOWEVER...AIR MASS NOT LOOKING PARTICULARLY COLD AND SFC
TEMPS LIKELY TO BE ABV FREEZING...LIMITING THE POTENTIAL OF
ACCUMS.
TEMPERATURES SHOULD REBOUND FRIDAY AHEAD OF ANOTHER NORTHERN STREAM
WAVE MOVING INTO THE MID-WEST. ECENS OUTPUT SUGGESTS THIS
SHORTWAVE WILL LIFT NORTH OF PA NEXT WEEKEND...PUSHING A DYING COLD
FRONT INTO THE REGION.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
COMBINATION OF RETREATING HIGH PRES OVR THE CANADIAN MARITIMES AND
WEAK LOW LIFTING UP THE MID ATLANTIC COAST WILL SPREAD AN
INCREASINGLY MOIST SERLY FLOW INTO CENTRAL PA ON TODAY. LOWER CIGS
LIFTING NORTHWARD THIS MORNING IN RESPONSE TO DEEPENING LLVL
MOISTURE AND ONSHORE FLOW. THE INCREASING MOISTURE...COMBINED
WITH LG SCALE FORCING AHEAD OF SHORTWAVE LIFTING OUT THE SE
STATES...COULD SPREAD A BIT OF LIGHT RAIN INTO SOUTHERN PA LATE
THIS AFTN.
MAIN CONCERN WILL BE POTENTIAL OF SOME LIGHT ICING...GIVEN COLD
AIR DAMMING SIGNATURE AND IMPLIED LOW-LEVEL AGEOSTROPHIC NORTHERLY
FLOW HOLDING LOW-LEVEL COLD AIR IN. OPER MDL SOUNDINGS AND ENS
PTYPES SUGGEST THE BEST CHC OF LATE DAY LIGHT -FZRA WOULD BE OVR
THE LAUREL HIGHLANDS AND HIGHER TERRAIN OF THE SC MTNS...WITH A
BETTER CHANCE TONIGHT ACROSS THE CENTRAL MTNS.
OUTLOOK...
TUE...LOW CIGS WITH DRIZZLE/LIGHT RAIN LIKELY. BECOMING BREEZY
MAINLY ACROSS HIGHER TERRAIN. LLWS POSS N/W.
WED...PERIODS OF RAIN ALONG WITH WIDESPREAD REDUCTIONS. BREEZY.
LLWS LIKELY.
THU...WINDY AND COLDER WITH SCT MVFR CIGS AND -SHSN. LLWS.
FRI...FAIR AND MOSTLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
FREEZING RAIN ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
PAZ024>028-033>036-056-063-064.
FREEZING RAIN ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065.
&&
$$
SYNOPSIS...DEVOIR/FITZGERALD
NEAR TERM...DEVOIR/FITZGERALD
SHORT TERM...DEVOIR/FITZGERALD
LONG TERM...FITZGERALD
AVIATION...DEVOIR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1112 AM EST MON DEC 22 2014
.SYNOPSIS...
HIGH PRESSURE WILL RETREAT NORTHEAST INTO THE CANADIAN MARITIMES
EARLY THIS WEEK...AS A WEAK LOW PRESSURE SYSTEM LIFTS UP THE MID
ATLANTIC COAST. AN INTENSIFYING STORM SYSTEM WILL TRACK WEST OF
PENNSYLVANIA WEDNESDAY NIGHT...PUSHING A COLD FRONT THROUGH
THE STATE. ANOTHER LESS POTENT COLD FRONT IS LIKELY TO IMPACT THE
REGION BY NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
16Z UPDATE** COLLAB WITH LWX AND PBZ ON ISSUING WSW ADVISORY FOR
FREEZING RAIN OVER LAURELS AND SOUTH CENTRAL MOUNTAINS.
LOW CLOUDS LIFTING CENTRAL MOUNTAINS AT MID MORNING
WITH DEEPER MOISTURE STARTING TO POOL SOUTH OF THE MASON DIXON
LINE...IN RESPONSE TO INCREASING MARITIME INFLUENCE IN INCREASING
EASTERLY/ONSHORE FLOW BETWEEN CAPE HATTERAS LOW PRESSURE AND
NORTHERN NEW ENGLANHIGH PRESSURE. THE INCREASING
MOISTURE...COMBINED WITH LG SCALE FORCING AHEAD OF SHORTWAVE
LIFTING OUT THE SE STATES...COULD SPREAD A BIT OF LIGHT RAIN INTO
SOUTHERN PA THIS AFTN. BLEND OF LATEST MDL GUIDANCE SUPPORTS CHC
POPS ACROSS THE SOUTHERN COUNTIES THIS AFTN.
FOR THE DAY...THE MAIN CONCERN FOCUSES ON POTENTIAL OF SOME ICING
LATER ON... GIVEN COLD AIR DAMMING AND LLVL AGEOSTROPHIC NLY FLOW
LOCKING THE COLD AIR IN. LATEST HRRR AND 4KM HRW-ARW DIFFER
SIGNIFICANTLY ON ARRIVAL OF PRECIP INTO SOUTH CENTRAL PA. LATEST
HRW-ARW HAS COME INTO LINE WITH PREVIOUS HRRR HOWEVER...IN
DELAYING PRECIP UNTIL AFTER 20Z...AND MOST OF THAT BEING RAIN
OVERF THE LOWER SUSQ RIVER VALLEY.
THUS...LATEST HI RES RUNS...FORECAST SOUNDINGS AND ENS PTYPES
SUGGEST THE BEST ICING CHANCE LATE THIS AFTERNOON...STARTING NEAR
THE MASON DIXON LINE MID TO LATE AFTERNOON...AND LIFTING NORTHWARD
INTO THE LAURELS AND SOUTH CENTRAL MOUNTAINS BEFORE DARK.
STILL NO ADVY TO BE POSTED AT THIS TIME DUE TO THE LOW CERTAINTY
OF MEASURABLE FZRA...BUT CONFIDENCE INCREASING FROM ADAMS COUNTY
WESTWARD THAT AN ADVISORY MAY BE NEEDED FROM ADAMS COUNTY WESTWARD
MID TO LATE AFTERNOON. WILL MONITOR TRENDS AND ISSUE ACCORDINGLY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
MOIST SERLY FLOW OFF THE ATLANTIC AND ASSOC OROGRAPHIC FORCING OF
SHALLOW MOISTURE LYR WILL LIKELY PRODUCE PATCHY LGT RAIN/DRIZZLE
TONIGHT AND TUESDAY. BEST CHC OF MEASURABLE PRECIP SHOULD COME
BTWN 00Z-06Z THIS EVENING WITH BENEFIT OF LG SCALE FORCING AHEAD
OF MID LVL SHORTWAVE. SFC TEMP FIELDS OF BOTH OPER AND ENSEMBLE
DATA SUGGEST THERE COULD BE ICING CONCERNS OVER THE HIGHER TERRAIN
OF CENTRAL PA. HOWEVER...TEMPS WILL BE VERY MARGINAL WITH ICING
MOST LIKELY ON THE RIDGETOPS. ALSO...NOT ENTIRELY SURE MEASURABLE
PRECIP WILL EVEN REACH FAR ENOUGH WEST TO CREATE A CONCERN. WILL
THEREFORE CONTINUE TO MENTION THREAT OF ICY ROADS IN THE HWO AND
AWAIT 12Z GUIDANCE TO GET A BETTER HANDLE ON THIS EVENT.
ANY ICING THREAT SHOULD END BY DAYLIGHT TUESDAY...WHEN ALL PLUME
MEMBERS RISE ABV FREEZING. RAINFALL AMTS TUESDAY SHOULD BE VERY
LIGHT...WITH SHALLOW MOISTURE IN MDL SOUNDINGS IMPLYING OCNL
DRIZZLE RATHER THAN RAIN.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
THE MOST SIGNIFICANT FORECAST ISSUE IN THE LONG TERM REMAINS THE
EVOLUTION OF DEEP TROUGH AND ASSOC SFC LOW TRACKING WEST OF PA
WED/WED NITE. STRONG SOUTHERLY FLOW AHEAD OF THIS SYSTEM SHOULD SCOUR
OUT LINGERING SHALLOW COLD AIR EAST OF THE APPALACHIANS. LOW-LEVEL
TEMPERATURE AND MOISTURE FIELDS RISE WELL ABOVE THEIR SEASONAL
VALUES...IMPLYING IT WILL BE A BALMY CHRISTMAS EVE FOR ALL.
ALL MED RANGE GUIDANCE TIMES THE TRAILING COLD FRONT THRU CENTRAL
PA WED NITE. A STRONG SOUTHERLY LL JET AND ASSOC PWAT ANOMALIES
ABOUT +3 SIGMA ABOVE NORMAL ARE PROGGED BY GEFS TO PASS THRU THE
AREA IN ADVANCE OF THE FRONT WED NITE. THIS STRONG SOUTHERLY
FLOW...HIGH PRECIPITABLE WATER AND SHARP CDFRONT ALL IMPLY A
FRONTAL RAIN EVENT WITH PERHAPS SOME RARE LATE DECEMBER (ELEVATED)
CONVECTION. HAVE ADDED CHC OF THUNDER BASED ON EXPECTED STRONG LG
SCALE FORCING IN ADVANCE OF UPPER TROF AND PRESENCE OF SOME MEAGER
MDL CAPES.
INTENSIFYING SFC LOW PASSING NORTH OF PA IS A FAVORABLE PATTERN
FOR STRONG WINDS ACROSS CENTRAL PA DURING THE COLD SEASON...SO STILL
MONITORING THE POTENTIAL OF STRONG WINDS COINCIDENT AND FOLLOWING
PASSAGE OF CDFRONT LATE WED NITE AND THURSDAY. WILL MENTION
POTENTIAL IN HWO.
COLDER AIR WORKING IN BEHIND COLD FRONT WILL LIKELY PRODUCE
OROGRAPHIC SNOW SHOWERS ACROSS THE ALLEGHENY PLATEAU ON CHRISTMAS
DAY. HOWEVER...AIR MASS NOT LOOKING PARTICULARLY COLD AND SFC
TEMPS LIKELY TO BE ABV FREEZING...LIMITING THE POTENTIAL OF
ACCUMS.
TEMPERATURES SHOULD REBOUND FRIDAY AHEAD OF ANOTHER NORTHERN STREAM
WAVE MOVING INTO THE MID-WEST. ECENS OUTPUT SUGGESTS THIS
SHORTWAVE WILL LIFT NORTH OF PA NEXT WEEKEND...PUSHING A DYING COLD
FRONT INTO THE REGION.
&&
.AVIATION /16Z MONDAY THROUGH FRIDAY/...
COMBINATION OF RETREATING HIGH PRES OVR THE CANADIAN MARITIMES AND
WEAK LOW LIFTING UP THE MID ATLANTIC COAST WILL SPREAD AN
INCREASINGLY MOIST SERLY FLOW INTO CENTRAL PA ON TODAY. LOWER CIGS
LIFTING NORTHWARD THIS MORNING IN RESPONSE TO DEEPENING LLVL
MOISTURE AND ONSHORE FLOW. THE INCREASING MOISTURE...COMBINED
WITH LG SCALE FORCING AHEAD OF SHORTWAVE LIFTING OUT THE SE
STATES...COULD SPREAD A BIT OF LIGHT RAIN INTO SOUTHERN PA LATE
THIS AFTN.
MAIN CONCERN WILL BE POTENTIAL OF SOME LIGHT ICING...GIVEN COLD
AIR DAMMING SIGNATURE AND IMPLIED LOW-LEVEL AGEOSTROPHIC NORTHERLY
FLOW HOLDING LOW-LEVEL COLD AIR IN. OPER MDL SOUNDINGS AND ENS
PTYPES SUGGEST THE BEST CHC OF LATE DAY LIGHT -FZRA WOULD BE OVR
THE LAUREL HIGHLANDS AND HIGHER TERRAIN OF THE SC MTNS...WITH A
BETTER CHANCE TONIGHT ACROSS THE CENTRAL MTNS.
OUTLOOK...
TUE...LOW CIGS WITH DRIZZLE/LIGHT RAIN LIKELY. BECOMING BREEZY
MAINLY ACROSS HIGHER TERRAIN. LLWS POSS N/W.
WED...PERIODS OF RAIN ALONG WITH WIDESPREAD REDUCTIONS. BREEZY.
LLWS LIKELY.
THU...WINDY AND COLDER WITH SCT MVFR CIGS AND -SHSN. LLWS.
FRI...FAIR AND MOSTLY VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
FREEZING RAIN ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
PAZ024>028-033>036-056-063-064.
FREEZING RAIN ADVISORY UNTIL 7 PM EST THIS EVENING FOR PAZ065.
&&
$$
SYNOPSIS...FITZGERALD
NEAR TERM...DEVOIR/FITZGERALD
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD
AVIATION...DEVOIR/RXR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
237 PM MST MON DEC 22 2014
.SHORT TERM...THIS EVENING THROUGH TUESDAY NIGHT
ISSUED AT 230 PM MST MON DEC 22 2014
UPPER LOW IS CENTERED OVER SD...WITH SURFACE LOW OVER
NORTHEAST SD. RAIN/SNOW IS WRAPPING AROUND THE LOW INTO WESTERN SD.
A TIGHT PRESSURE GRADIENT IS KEEPING NORTHWEST WINDS STRONG THIS
AFTERNOON...ESPECIALLY JUST EAST OF THE HILLS. TEMPS ARE IN THE 30S
TO LOW 40S.
WINDS WILL BECOME MORE NORTHERLY TONIGHT AS THE LOW SLIDES
SOUTHEASTWARD. STRONG WINDS OF 25-35 KTS WITH HIGHER GUSTS ARE STILL
EXPECTED THROUGH THE NIGHT...WITH THE STRONGEST WINDS GRADUALLY
SHIFTING SOUTHWARD. TWEAKED THE ADVISORIES TO CONVERT RAPID CITY AND
CUSTER COUNTY PLAINS TO WINTER WEATHER ADVISORIES FOR BLOWING SNOW
THIS EVENING AFTER THOSE AREAS RECEIVE SNOW. EXTENDED THE WIND
ADVISORY FOR THE SOUTHEASTERN FOOTHILLS AND THE FALL RIVER PLAINS
THROUGH TUESDAY MORNING. WILL LET SOUTHERN FOOTHILLS WIND ADVISORY
EXPIRE THIS EVENING...AS DO NOT EXPECT AS STRONG WINDS THERE WITH
THE MORE NORTHERLY DIRECTION.
MOST OF THE SNOW WILL FALL OVERNIGHT...AND TOTAL AMOUNTS HAVE NOT
CHANGED MUCH FROM PREVIOUS FORECAST. LOOKS LIKE AN ADDITIONAL 6 TO 9
INCHES IS POSSIBLE IN THE NORTHERN HILLS...WITH ABOUT 3 TO 5 INCHES
ON THE SD PLAINS...POSSIBLY MORE AROUND THE SHANNON/JACKSON/BENNETT
COUNTY AREAS. FOR THE RAPID CITY AREA...1-3 INCHES STILL LOOKS ON
TRACK. THREAT OF MOST CONCERN WILL BE THE REDUCED VISIBILITIES DUE
TO BLOWING SNOW...WHICH COULD RESULT IN WHITE-OUT CONDITIONS AT
TIMES. CONSIDERED A WARNING FOR THE SHANNON/JACKSON/BENNETT
AREAS...BUT MAINLY FOR BLOWING SNOW. WINDS DO NOT LOOK INCREDIBLY
STRONG THERE...AND ALTHOUGH SNOW AMOUNTS MAY APPROACH WINTER STORM
WARNING CRITERIA...THINK THE WINTER WEATHER ADVISORY SHOULD COVER
THE THREAT FOR BLOWING SNOW.
BREEZY WINDS WILL CONTINUE ON TUESDAY...AND SNOW WILL LINGER LONGEST
OVER SOUTH CENTRAL SD. SKIES WILL GRADUALLY CLEAR FROM WEST TO
EAST...AND HIGHS WILL BE IN THE 30S. LOWS TUESDAY NIGHT WILL BE IN
THE TEENS.
.LONG TERM...WEDNESDAY THROUGH MONDAY
ISSUED AT 230 PM MST MON DEC 22 2014
ALTHOUGH EXTENDED PERIOD STARTS UNDER UPPER RIDGING...
LONG WAVE TROF DEEPENS OVER THE WESTERN US...INFLUENCING THE WEATHER
OVER THE PLAINS THROUGH THE WEEK BEFORE MOVING EASTWARD AND NEXT
SYSTEM MOVES ONSHORE. BROAD RIDGE WILL BE IN PLACE OVER THE ROCKIES
AND NORTHERN PLAINS WED WHILE SURFACE LOW TRACKS ACROSS SOUTHERN
CANADA WITH A WARM FRONT MOVING NORTH. FORECAST AREA WILL BE IN THE
WARM SECTOR WITH SOUTHWEST WINDS AND PARTLY CLOUDY SKIES...WHICH
WILL WARM TEMPERATURES INTO THE 40S OVER FAR SOUTHWESTERN SD AND THE
NORTHERN AND EASTERN SLOPES OF THE BLACK HILLS. WITH POTENTIAL
SNOWFALL FROM CURRENT STORM...TEMPERATURES PROBABLY WILL NOT GET
INTO THE 50S. COLD FRONT WILL DROP ACROSS THE AREA LATE ON CHRISTMAS
EVE. AS TROF MOVES OVER THE ROCKIES...PRECIPITATION WILL SPREAD
NORTHEASTWARD AHEAD OF IT...WITH MODELS CONVERGING ON THE SURFACE
LOW TRACK ACROSS THE CENTRAL PLAINS INTO THE MISSOURI RIVER
VALLEY...WHICH WOULD GIVE SOUTH CENTRAL SD THE MOST SNOW.
PRECIPITATION SHOULD BE JUST SNOW AS AIRMASS IS DRY WHEN FORECAST
SOUNDINGS SHOW TEMPERATURES ABOVE FREEZING...BUT COOLS QUICKLY
BEHIND COLD FRONT BEFORE BECOMING SATURATED AND BETTER DYNAMICS
REACH THE AREA. TROF CLEARS THE AREA FRIDAY MORNING. AN ALBERTA
CLIPPER SYSTEM DROPS ACROSS THE NORTHERN PLAINS LATE FRIDAY...GFS
SHOWS IT WEAK WITH VIRTUALLY NO QPF...BUT ECMWF HAS A STRONGER
SOLUTION...SO POPS MAY INCREASE IN SUBSEQUENT FORECASTS. ARCTIC HIGH
WILL PUSH SOUTHWARD...WITH MUCH COOLER TEMPERATURES FRIDAY. ANOTHER
ARCTIC HIGH WILL FORCE A BACKDOOR COLD FRONT WESTWARD OVER THE
AREA...WITH EVEN COOLER TEMPERATURES. NEXT SYSTEM DEEPENS AS IT
MOVES FROM THE PACIFIC NORTHWEST INTO THE GREAT BASIN...WITH MORE
SNOW POSSIBLE EARLY NEXT WEEK.
&&
.AVIATION...FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING
ISSUED AT 230 PM MST MON DEC 22 2014
SNOW IS INCRSG OVR WRN SD THIS AFTN...WITH CIGS/VSBY
LOWERING. EXPECT MVFR/IFR CONDITIONS OVER MOST PLACES XCPT
DOWNSLOPED AREAS FROM RAP TO HSR. GUSTY NW WINDS WILL CONTINUE THRU
THE NIGHT...LEADING TO LWR VSBYS IN BLOWING SNOW. SNOW AND WNDS WL
DCRS TUESDAY MORNING AND CIGS/VIS WILL GRADUALLY IMPROVE THRU THE
DAY.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER STORM WARNING UNTIL NOON MST TUESDAY FOR SDZ024-025.
WINTER WEATHER ADVISORY UNTIL NOON MST TUESDAY FOR SDZ013-014-
028-031-032-042>044-072-073.
WINTER WEATHER ADVISORY UNTIL 6 PM CST TUESDAY FOR SDZ046-047-
049.
WIND ADVISORY UNTIL NOON MST TUESDAY FOR SDZ041-074.
WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY FOR SDZ001-002-
012.
WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO NOON MST
TUESDAY FOR SDZ026-030.
WIND ADVISORY UNTIL 8 PM MST THIS EVENING FOR SDZ027-030.
HIGH WIND WARNING UNTIL 8 PM MST THIS EVENING FOR SDZ026.
WY...WINTER STORM WARNING UNTIL NOON MST TUESDAY FOR WYZ057.
WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY FOR WYZ056-071.
&&
$$
SHORT TERM...POJORLIE
LONG TERM...55
AVIATION...55
AREA FORECAST DISCUSSION
NWS AUSTIN/SAN ANTONIO TX
1222 PM CST MON DEC 22 2014
.AVIATION...
MOST OF THE LOW CLOUDS HAVE ERODED DUE TO THE DOWNSLOPING WESTERLY
COMPONENT IN THE LOWER AND MID LEVELS. WE CONTINUE TO SEE SOME IFR
DECKS AT DRT BUT SHOULD SEE THIS DISSIPATE IN THE NEXT HOUR OR SO.
HIGH LEVEL CLOUDINESS WILL PERSIST THIS AFTERNOON ACROSS ALL THE
AREA. WINDS WILL VEER TO A WESTERLY DIRECTION BY LATE AFTERNOON
WITH EVEN SOME LIGHT NORTHERLY WINDS POSSIBLE BY LATE EVENING.
NAM MODEL IS VERY BULLISH IN BRINGING A REPEAT OF IFR INTO
SAT/SSF IN THE MORNING BEFORE THE BIG FRONTAL PUSH. HRRR IS ALSO
STARTING TO HIT THIS SCENARIO. THEY ARE BANKING ON THE WESTERLY
FLOW DYING OFF THIS EVENING AND A RETURN OF SE WINDS BEFORE THE
FRONT ARRIVES.
THE TRUE COLD FRONT WITH COLDER AIR AND STRONGER SPEEDS WILL WAIT
UNTIL TUE MORNING. ALONG WITH THE COLD AIR ADVECTION...MODELS ARE
DEVELOPING SOME OVERUNNING CLOUDS BELOW 850 MB. WILL BRING DECKS
DOWN TO MVFR AT ALL SITES BY 16Z TOMORROW. WE WILL LIKELY HAVE
SOME SORT OF LIGHT PRECIPITATION AT AUSTIN IN THE MORNING BUT AM
NOT CONFIDENT ENOUGH WITH TIMING AND OVERALL POP CHANCES TO INPUT
AT THIS TIME. WILL WATCH LATER RUNS TO SEE IF THIS TREND
CONTINUES. N AND NW WINDS WILL BE RATHER GUSTY OVER 20 KTS TUE
AFTERNOON ESPECIALLY ALONG THE ESCARPMENT.
&&
.PREV DISCUSSION... /ISSUED 917 AM CST MON DEC 22 2014/
UPDATE...
WITH SOME LOCATIONS ON THE PLATEAU STILL REPORTING FOGGY
CONDITIONS AT 15Z. EXTENDED PATCHY FOG MENTION FOR THESE LOCATIONS
ANOTHER FEW HOURS. ALSO RAN STANDARD UPDATE FOR HOURLY T TRENDS
AND DEW T. OTHERWISE...FORECAST ON TRACK.
PREV DISCUSSION... /ISSUED 600 AM CST MON DEC 22 2014/
AVIATION...
STRONG SOUTHEASTERLY FLOW ABOVE THE SURFACE HAS RESULTED IN
IFR/LIFR CIGS THIS MORNING. ALSO SEEING VIS REDUCED IN FOG WITH
THE WORST VIS AT DRT. CONDITIONS SHOULD IMPROVE BY AROUND NOON AS
WEST WINDS MOVE IN. A COLD FRONT WILL MOVE THROUGH THE REGION
TUESDAY BRINGING NORTH WINDS BY MID-MORNING.
PREV DISCUSSION... /ISSUED 408 AM CST MON DEC 22 2014/
SHORT TERM (TODAY THROUGH TUESDAY)...
FOG COVERS MOST OF SOUTH CENTRAL TEXAS EARLY THIS MORNING. A
DEEPENING TROUGH MOVING OUT INTO THE PLAINS WILL CAUSE SOUTHWEST
TO WESTERLY LOWER LEVEL WINDS. LOW CLOUDS AND FOG ERODE FROM WEST
TO EAST BY MID MORNING ALLOWING TEMPERATURES TO RISE TO WELL ABOVE
AVERAGE THIS AFTERNOON. A PRE-FRONTAL TROUGH MOVES ACROSS OUR AREA
TONIGHT...THEN A COLD FRONT EARLY TUESDAY WITH AN UPPER LEVEL
TROUGH LATE TUESDAY. THE FRONT AND UPPER TROUGH GENERATE UPWARD
MOTION OF SUFFICIENT MOISTURE TO PRODUCE SLIGHT CHANCE TO CHANCE
POPS FOR SHOWERS NORTHEAST OF A ROCKSPRINGS TO NEW BRAUNFELS TO
KARNES CITY LINE. RAINFALL WILL BE LIGHT WITH AMOUNTS LESS THAN
ONE QUARTER INCH. COLD ADVECTION AND CLOUD COVER WILL DROP
TEMPERATURES TO BELOW AVERAGE ON TUESDAY. BREEZY CONDITIONS WILL
DEVELOP IN THE WAKE OF THE FRONTAL PASSAGE DUE TO TIGHT PRESSURE
GRADIENT.
LONG TERM (TUESDAY NIGHT THROUGH SUNDAY)...
THE BREEZY CONDITIONS CONTINUE INTO TUESDAY NIGHT KEEPING THE
TEMPERATURES FROM BOTTOMING OUT...ONLY FLIRTING WITH THE FREEZING
MARK IN SOME LOW LYING AND WIND SHELTERED HILL COUNTRY SPOTS
WEDNESDAY MORNING. BELOW AVERAGE TEMPERATURES CONTINUE CHRISTMAS
EVE THROUGH CHRISTMAS MORNING. MORE WIDESPREAD FREEZING
TEMPERATURES ARE EXPECTED CHRISTMAS MORNING AS THE SURFACE HIGH
SETTLES OVER THE AREA...BUT STILL MAINLY IN LOW LYING SPOTS IN
THE HILL COUNTRY AND ALONG THE ESCARPMENT. THE SURFACE HIGH MOVES
OFF TO THE EAST ALLOWING A SOUTHERLY FLOW AND TEMPERATURES WARMING
TO ABOVE AVERAGE FOR CHRISTMAS AFTERNOON. A ZONAL FLOW ALOFT
PREVAILS FRIDAY THROUGH SUNDAY WITH THE MODELS DELAYING THE NEXT
STRONG COLD FRONT UNTIL FRIDAY NIGHT INTO EARLY SATURDAY. HAVE
WARMED FRIDAY AFTERNOON TEMPERATURES ONLY SLIGHTLY. SOME MODELS
ARE SHOWING RAIN CHANCES. HOWEVER...MOISTURE WILL BE LIMITED AND
HAVE NOT INCLUDED POPS. BELOW AVERAGE TEMPERATURES ARE EXPECTED
SATURDAY AND SUNDAY WHICH WILL LIKELY CONTINUE BEYOND THIS
FORECAST THROUGH THE NEW YEAR.
&&
.PRELIMINARY POINT TEMPS/POPS...
AUSTIN CAMP MABRY 73 49 56 38 56 / 0 10 30 - 0
AUSTIN BERGSTROM INTL AIRPORT 72 47 57 37 56 / 0 10 20 - 0
NEW BRAUNFELS MUNI AIRPORT 74 49 58 38 57 / 0 10 10 - 0
BURNET MUNI AIRPORT 71 46 54 36 53 / - 10 30 0 0
DEL RIO INTL AIRPORT 75 48 59 37 59 / 0 - - 0 0
GEORGETOWN MUNI AIRPORT 70 47 55 36 54 / 0 10 30 - 0
HONDO MUNI AIRPORT 75 46 61 35 59 / 0 - 10 0 0
SAN MARCOS MUNI AIRPORT 72 48 57 36 56 / 0 10 20 - 0
LA GRANGE - FAYETTE REGIONAL 73 52 57 38 56 / - 10 30 - 0
SAN ANTONIO INTL AIRPORT 75 50 59 38 58 / 0 - 10 - 0
STINSON MUNI AIRPORT 75 50 59 38 59 / 0 - 10 - 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE/AVIATION...09
SYNOPTIC/GRIDS...29
PUBLIC SERVICE/DATA COLLECTION...33