Precipitation-type-related forecast discussions

COMPOSITE RADAR SHOWS BAND OF WAA INDUCED PRECIP ACRS NRN/CENTRAL IL ATTM AHD OF S/WV TROF MOVG INTO IA. VORT MAX ASSOC WITH THIS TROF LOOKS ON WATER VAPOR LOOP TO BE MOVING INTO NW IA/SW MN ATTM. AS POINTED OUT BY SWOMCS...292K ISENTROPIC SFC THIS MORNING SHOWED ABT 2.5 G/KG MIXING RATIO WHERE IT INTERSECTED 750MB SUGGESTING MAX 5 INCH AMNTS PER GARCIA METHOD. ETA TRACK OF VORT MAX ACRS SRN WI APPEARS REASONABLE THOUGH SPEED LOOKS TO BE A BIT SLOW. BASED ON THIS TRACK EXPECT HEAVIEST SNOW AMOUNTS IN NRN IL IN THE 1 TO 2 INCH RANGE. ETA FCST SOUNDINGS SUGGESTS ALL SNOW FOR CHI WITH A FREEZING RAIN SLEET MIXTURE FROM JUST SOUTH OF CHI-MLI LINE DOWN TO AROUND MTO. ACARS SOUNDINGS FM ORD AND PIA OBS SUGGESTS THESE SOUNDINGS VERIFYING WELL. PLAN ON CONTG WINTER WEATHER/FREEZING RAIN ADVISORIES ISSUED EARLIER TODAY INTO THE EVENING SOUTH AND EAST OF THE IL RIVER. ALTHOUGH TEMPS AHD OF THE PRECIP AREA HAVE RISEN ABV FREEZING IN EAST CENTRAL IL, GROUND IS LIKELY COLDER FM RECENT COLD SNAP THE PAST COUPLE OF DAYS AND DEWPOINTS ARE WELL BELOW FREEZING.

TAYLOR

NOT MUCH MAJOR SYSTEM CHG IN LAST 24 HOURS. PROGS WERE A LITTLE SLOW TDA WITH THE SHEARED PVA IN CMTL IL DROPPING SWD BUT HAVE CAUGHT UP TNGT. THIS ACTUALLY SHOWS UP AS 7H TROF ARND MAJOR CIRCULATION IN ERN CANADA. SHUD EXPECT ASSOC BAND OF HIER CLDS IN TROF TO PROGRESS SWD TDA AND OUT OF IL BY LT THIS AFTN. SO SHOULD RSNBLY XPECT TO SEE DECENT AMNT OF SUNSHINE FOR SRN HLF IL TDA AND FAIR TONIGHT AND THURSDAY. UPR TROF IN NRN ROCKIES FIRES A PIECE OF ENERGY ACRS CNTL PLAINS TNGT ABD ACRS IL THUR. THIS S/W SO WEAK AND MSTR LIMITED THAT XPECT ONLY SOME CI OR HI BKN AC ACROSS MID SECTIONS ON THU.

NOW FOR THE MAIN CONCERN...NRN IL/NWRN IN. BUFKIT A LTL TOO SLO YDA. INVERSION BELOW 850MB LIFTED SOONER THAN EXPECTED AND SHWRS BEGAN BFR MIDNIGHT ACRS NERN IL. ACARS SHOWING 850MB TEMPS ARND -4 WITH PROGS TO -6 TDA. SOME SNOW MIXED IN WITH RAIN ESP NR THE LAKEFRONT. CU CURVES WWD ACRS NCNTL IL TO MLI-UIN. RATHER CLR ACRS RFD-DBQ AREA. CU FM NRN LK MICH RIDING THRU NUCH DRIER AIR AND DISSIPATES BEFORE REACHING NRN IL. HAVE BEEN EXPECTING WINDS TO BECOME MORE NRLY AS FLOW BECOMES LESS ANTICYCLONIC. HOWEVER FLOW OFF LK MICH ON MODELS STILL MAINTAINS NERLY ORIENTATION THRU 30 HOURS. TRAJ FM LK MICH SHIFTS SEWRD HOWEVER SO THAT BY 18Z TDA PLUME OFF LK MICH DIRECTED MORE TO SPI THAN BRL. MODELS DON/T REALLY PRJECT NORTH FLO UNTIL 36 HRS OR THU AM. TEMPS STILL IN -4 TO -6 RANGE AND FETCH LONGER THEN SO SEE NO NEED TO CHG FM MIXING SNOW WITH RAIN ON THU FOR NWRN IN/SERN CHI. WINDS WEAKEN TNGT AND THUR THAN TDA PLUME PROBABLY NOT EXTENDING AS FAR AWAY FROM LAKE.

BRUMER

SHORT TERM DISCUSSION FOR NORTHEAST AND NORTH CENTRAL COLORADO: RADAR/SATELLITE PICTURES SHOW PRECIPITATION ON THE SLIGHT DECREASE IN THE IMMEDIATE UPSTREAM. VAD WIND/PLATTEVILLE PROFILERS BOTH SHOWING UPSLOPE WIND COMPONENT UP TO AROUND 600MB. GRIDS SHOWING LOW AND MID LEVELS TO REMAIN SATURATED THROUGH THE PERIOD TODAY...WITH THE UPSLOPE TO CONTINUE. MODELS SHOW UPPER SYSTEM MOVING SLOW ENOUGH THROUGH THE DAY TO KEEP SOME WEAK SYNOPTIC LIFT OVER THE FORECAST AREA THROUGH SUNSET. CROSS SECTIONS CONTINUE TO SHOW GOOD POTENTIAL INSTABILITY THROUGH THE DAY WITH ONLY FAIR LAPSE RATES . PRECIPITATION GRIDS FROM THE 03Z ETA AND THE FORECAST SYSTEMS LABORATORY'S SCALABLE FORECAST MODEL SHOW SOME MODEST AMOUNTS THROUGH THE DAY THROUGH MOST OF THE FORECAST AREA. ALL AND ALL...EXPECT CURRENT SITUATION TO BASICALLY CONTINUE THROUGH THE DAY. AS FAR AS THE SNOW/RAIN...FREEZING LEVEL SITUATION IS CONCERNED...TEMPERATURE/THICKNESS GRIDS POINTING TO A 1.0-1.5C COOL OFF FROM YESTERDAY FOR TODAY/S HIGHS. SO BY LATE AFTERNOON SNOW MAY BE MIXING IN OVER THE PLAINS. RAWS/SNOTEL OBSERVATIONS AND SOME CURRENT AIRCRAFT SOUNDINGS SHOWING CURRENT FREEZING LEVEL ABOUT 8000 FEET ACROSS MOST OF THE FORECAST AREA. BEST AS I CAN TELL...THE ALPINE AREAS CURRENTLY HAVING VERY LITTLE OR VERY LIGHT PRECIPITATION. WITH MODELS SHOWING POOR TO NO OROGRAPHIC FLOW...MID AND UPPER LEVEL MOISTURE ON THE DECREASE...AND NEARLY NO Q-G ASCENT...WILL GO VERY LITTLE ACCUMULATION IN THE MOUNTAINS. MAY EVEN GO SCATTERED IN ZONES 30/32/33/35. THE HIGHEST AMOUNTS...BUT NOT THAT MUCH...CAN BE EXPECTED IN ZONES 36...37 AND 34 SOUTH OF I-70.

RJK

SATELLITE IMAGERY AND PRESSURE GRADIENTS SHOW OLD STRETCHING OCCLUSION OVER THE CASCADES AT 16Z FOLLOWED BY COOL UNSTABLE NWLY FLOW ALOFT. WITH EXCEPTION TO UNDERESTIMATING STRENGTH OF 150 KT JET STREAK AIMED TOWARD SRN ORE AND NRN CA...MODELS APPEAR WELL INITIALIZED AND RATHER CONSISTENT WITH PREVIOUS RUNS WITH 12Z NGM ONLY SLIGHTLY SLOWER THAN PREFERRED ETA IN TRANSITIONING TO WEAK OFFSHORE FLOW THIS AFTERNOON. CURRENT FORECASTS STATEWIDE LOOK GOOD AND REQUIRE ONLY MINOR ADJUSTMENT.

.WESTERN WASHINGTON... LOW SNOW LEVELS WITH SHOWERS IN NW FLOW AS 16Z SURFACE TEMPERATURES IN MID AND UPPER 30S AND ACARS FROM SEATAC SHOWING FREEZING LEVELS NEAR 2000 FT (A DROP OF 500 FEET SINCE 12Z). HENCE WILL DROP SNOW LEVEL LOCALLY TO 1000 FT THIS AFTERNOON AND INTRODUCE ICE PELLETS AND SHOWERS DOWN TO SEA LEVEL.

CAPES THIS AFTERNOON AS DEPICTED BY 03Z MESO ETA OVER 750 J/KG WITH COOL AIR ALOFT AND SOME INSOLATION. SO WILL MAINTAIN CHANCE OF AFTERNOON THUNDERSTORMS WITH CONVERGENCE ZONE. SNOW RATES IN THE MOUNTAINS NEAR AN INCH AN HOUR WITH THE FRONT. THIS COULD LOCALLY CONTINUE THIS AFTERNOON WITH CONVERGENCE SO WILL ISSUE MARGINAL SNOW ADVISORY FOR CENTRAL CASCADES TODAY.

SHOWERS WILL GRADUALLY DECREASE AS CONVERGENCE AND ONSHORE FLOW DIMINISHES TONIGHT AND THU MORNING. NO CHANGES TO POPS

ALBRECHT

CONTINUATION OF MOIST CYCLONIC FLOW WILL RESULT IN MORE OF THE SAME FOR IL TODAY...OCCASIONAL LIGHT RAIN AND DRIZZLE AS VARIOUS MINOR WAVES MOVE THROUGH. MAIN UPPER LOW LOCATED OVER NORTHERN OH IN WATER VAPOR SATELLITE LOOP PROGGED TO MOVE NORTHEAST TODAY AND TONIGHT WITH CYCLONIC MID AND LOW LEVEL FLOW WEAKENING WITH TIME. UPPER RIDGING INTO MID MS VALLEY TODAY BETWEEN NORTHEAST SYSTEM AND NEXT MAJOR PLAYER ON AZ/NM BORDER PER SATELLITE COMBINED WITH WEAKENING CYCLONIC FLOW SHOULD RESULT IN DECREASE IN LIGHT RAIN...ESPECIALLY IN SOUTHERN PART OF ILLINOIS...LATER TODAY.

CAA AS INDICATED BY BACKING OF WINDS WITH HEIGHT IN PROFILERS HAS COOLED LOWER LEVELS ENOUGH TO SUPPORT SNOW AT MKE AND ENW EARLIER THIS MORNING. AIRCRAFT SOUNDINGS IN THE MKE AND ORD AREAS SHOW FREEZING LEVEL ABT 890 MB BUT FEEL SNOW SHOULD HOLD OFF UNTIL TONIGHT WHEN UPPER LOW PARKED OVER SD PER PROFILERS MOVES INTO NW IL AND ACROSS NORTHERN IL DURING THE DAY TUE.

WITH CAA AND OVERCAST TEMPERATURES WILL MAKE LITTLE UPWARD PROGRESS TODAY SO WILL GO WITH STEADY TEMPERATURE...UPPER 30S NORTH TO MID 40S SOUTH. TEMPERATURE DROP TONIGHT NOT EXPECTED TO BE MORE THAN 5 TO 8 DEG ACROSS THE STATE WITH SIMILAR RISES THURSDAY.

TRS

12Z ETA DVLPS SFC LOW FURTHER OFF SC COAST THAN WITH PREVIOUS RUNS. THUS PRECIP WITH THIS FEATURE LOOKS TO BE MAINLY OFFSHORE. MOST FORCING IS WITH VIGOROUS UPPER LEVEL SHORT WAVE AND JET MAX AND THE ETA SHOWS A BRIEF PERIOD OF LIGHT PRECIP WITH THIS FEATURE LATE TONIGHT AND EARLY WED MORNING. AT THIS TIME AM LOOKING AT POPS IN THE 40 TO 50 RANGE BASED ON BLEND OF CENTRAL AND LOCAL GUIDANCE. ANALYSIS OF SOUNDINGS AND THICKNESS FORECASTS INDICATES PRECIP TYPE AS MOSTLY SNOW OVER SC MIDLANDS...POSSIBLY MIXED WITH A LITTLE SLEET. FURTHER SOUTH AND EAST FROM AGS TO OGB TO FLO...A MIXTURE OF RAIN...SLEET AND SNOW. ALONG THE COAST FROM NBC TO MYR MAINLY RAIN. ACARS SNDGS HAVE WARMED A LITTLE BELOW 700MB BETWEEN 14Z AND 16Z...BUT TEMPS ARE STILL AROUND THE -4C MARK. THICKNESSES ARE COLDER WITH THE LATEST RUN THAN WITH THE PREVIOUS RUNS. AT THIS TIME EXPECT ANY PRECIP AMTS TO BE LIGHT...LESS THAN 1/10 INCH. WITH SFC TEMPS AROUND THE FREEZING LEVEL EXPECT LITTLE IF ANY ACCUMULATION OF SNOW OR SLEET. GREATEST POTENTIAL FOR ACCUMULATION IS OVER THE NRN MIDLANDS...N OF A LINE FROM NEWBERRY TO CAE TO CHESTERFIELD. AT THIS TIME WITH LOW POPS AND LIGHT PRECIP...NO ADVISORY ANTICIPATED.

MWC

VORT MAX SEEN ON IR LOOPS LIFTING NE ACRS SRN IA ATTM. MODELS IN GOOD AGREEMENT THAT THIS FEATURE WILL WEAKEN AS IT LIFTS NE ACRS NWRN IL TODAY. 88D'S SHOWING BANDS OF WAA PRECIP OVER NW 1/4 OF IL ATTM. PRECIP AREA EXPECTED TO CONT EXPANDING ACRS NRN IL THIS MORNING THEN LIFT NE OF THE STATE THIS AFTERNOON. PRECIP MOSTLY SNOW THOUGH SOME FREEZING RAIN HAS BEEN REPORTED NEAR THE MS RIVER. WL LEAVE ADVISORIES IN TACT FOR THIS MORNING. ACARS SOUNDIGS FROM ORD SUGGESTS PRECIP WL BE SNOW AS IT MOVES INTO NC/NE IL. 2.5 G/KG MIXING RATIONS UPSTREAM SUGGEST POTENTIAL FOR UP TO 5 INCHES OF SNOW. HEAVIEST ACCUMS WL BE OVER FAR NW WHERE SATURATION WL PERSIST THE LONGEST...MORE BANDED SNOW FURTHER SE. WL TAPER OFF ACCUMS TO LESS THAN AN INCH OVER CENTRAL IL INTO NW IND. SNOWFALL COULD END AS A PERIOD OF DRIZZLE OR FREEZING DRIZZLE AS H85 LOW STAYS WEST OF THE STATE THIS AFTERNOON AND TONIGHT PROVIDING SOME WK LIFT OF SATURATED LOWER LEVELS. ANOTHER S/W MOVG EAST ACRS PLAINS STATES THU SHOULD HAVE SIMILAR RESULTS ACRS NRN IL AS SATURATED LAYERS WILL BE CONFINED TO LOW LVLS.

TAYLOR

SHORT TERM: BASED CURRENT SURFACE OBSERVATIONS AND LATEST ACARS TEMPERATURE PROFILES...WILL REMOVE ALL MENTIONS OF FREEZING RAIN FROM THE FORECAST EXCEPT FOR NE CT. FREEZING LEVEL IS AT 6000 FT. OVERALL PATTERN OF THE MODELS SHOWS REASONABLE AGREEMENT WITH WEAK SFC LOW MOVING UP THE MID ATLANTIC REGION AHEAD OF THE PACIFIC COLD FRONT WHICH MOVES ACROSS THE REGION BETWEEN 06Z AND 12Z WEDNESDAY.

ON THE QPF SIDE...THERE IS AN OBVIOUS LACK OF A MOISTURE PLUME ON SATELLITE. THETA E RIDGE SLIDES EAST OF THE REGION BY EVENING. PW'S ARE IN THE 1 INCH RANGE WHICH IS 200% OF NORMAL THIS AFTERNOON. WITH THE STRONG WARM AIR ADVECTION...SOUTHEAST FLOW...PERSISTENT QC FORCING SEEN IN THE MODELS AND THE LARGE SHIELD OF PCPN EXPECT THE MODEL QPF/S TO VERIFY. THUS EXPECT JUST UNDER AN INCH OVERALL. THIS IS BELOW LATEST FFG OF 1.5 TO 2 INCHES FOR THE 3 TO 6 HOUR PERIOD. STEADY PCPN TO TAPER TO MORE SHOWERY THIS EVENING AND TONIGHT.

TEMPS...FLOW OFF OCEAN SHOULD KEEP US DOWN A BIT BELOW FWC GUIDANCE.

WINDS...STABLE LOW LEVEL SITUATION PREVENTS WINDS FROM MAKING IT DOWN TO SURFACE. WILL TONE THIS DOWN IN ZONES.

.WEDNESDAY...FRONT IS PAST REGION BY 12Z...BUT IS HUNG UP A BIT IN CLEARING THE AREA. ETA SHOWING RESIDUALMOISTURE. PLAN TO LEAVE A CHANCE FOR A SHOWER ESPECIALLY EAST.

TONGUE

LOW PRESSURE DEVELOPING SOUTH OF LI AS SEEN IN THE CURRENT PRESSURE AND WIND FIELDS. THIS FITS THE 18Z ETA WELL.

CURRENT PCPN TYPE IS RAIN IN THE OKX FCST AREA EXCEPT NYZ067 WHERE COLDER AIR ALOFT IS MAKING FOR RAIN MIXED WITH SNOW. LOW PRESSURE OFF LONG ISLAND BECOMING THE MAIN LOW AND PCPN INTENSIFYING AS A RESULT.

THIS LOW WILL MAKE FOR A WESTERLY FLOW TO SET UP HELP TO RUSH THE COLD FRONT INTO THE REGION WEDNESDAY AM. LATEST ACARS SOUNDINGS SHOW FREEZING LEVEL STILL UP AT 4K FEET IN THE NYC AREA WITH 1K IN THE BDL AREA. THE FREEZING LEVEL WILL DROP SOME THROUGH THE NIGHT...BUT EXPECT LIQUID FOR THE MAJORITY OF THE REGION. INLAND... ORANGE AND PUTNAM COUNTIES...THE MIXED RAIN WILL CHANGE PRIMARILY TO SNOW...SOME MIX IN THE COLDER NW ZONES.

AS COASTAL LOW MOVES OUT IN THE OVERNIGHT...EXPECT PRECIPITATION TO BE ON A DIMINISHING TREND FROM EAST TO WEST. WILL ADD A LIGHT ACCUMULATION TO THE INTERIOR ZONES.

WEDNESDAY...ANY MORNING PCPN WILL QUICKLY CHANGE OVER TO SNOW AS TEMPS FALL. WILL NOT HAVE ANY ACCUMULATION WITH THE CHC POPS.

WINDS EXPECTED TO GUST TO JUST BELOW THE WIND ADVISORY CRITERIA. CURRENT FCST WIND MAX LOOKS TO BE RIGHT ON. WILL ADJUST WORDING AS EARLY MORNING WINDS WILL NOT BE THAT BAD.

TONGUE

MAIN FORECAST PROBLEM WITH THIS PACKAGE IS WHETHER OR NOT A SNOW ADVISORY SHOULD BE WARRANTED.

LATEST WATER VAPOR LOOP SHOWS TWO DISTINCT SHORTWAVES. ONE OF THE SHORTWAVES IS ROTATING THROUGH NORTHWEST AR WHILE THE OTHER IS MOVING THROUGH THE GREAT LAKES. AHEAD OF THESE WAVES...ISENTROPIC LIFT CONTINUES TO TAKE PLACE ACROSS THE OH VLY. CURRENT KPAH RDAR LOOP SHOWS A BAND OF LIGHT SNOW MOVING THROUGH SW KY WHICH IS ASSOC WITH THE SHORTWAVE IN AR. MODELS PROG THIS SHORTWAVE TO DIVE SOUTHEAST TODAY AND SHEAR OUT AT THE SAME TIME. SOUTH CENTRAL KY MAY SEE ABUST OF SNOW EARLY THIS MORNING...BUT ACCUMULATIONS SHOULD BE LESS THAN AN INCH.

THE SECOMD SHORTWAVE ACROSS THE NORTH IS ONLY PRODUCING SOME LAKE EFFECT SNOW AT THE MOMENT. NM SEEMS TO BE TOO AGRESSIVE WITH THIS WAVE TO THE NORTH IN PRODUCING PCPN IN NORTH CENTRAL KY EARLY THIS AFTERNOON. WE WENT THE SLOWER ETA SINCE WE BELIEVE MOST OF PCPN SHOULD BE FOCUSED JUST AHEAD OF AND ALONG THE FRONT. LATEST ACARS SOUND SHOWS A 60 KT 850JET OVER KSDF WHICH WAS POORLY IDENTIFIED BY THE MODELS. WE BUMPED UP THE WINDS A LITTLE MORE TODAY WITH THAT IN MIND.THIS MAY ALSO BUMP UP TEMPERATURES MORE THAN PROGGED MAINLY AT 850MB WHICH COULD HELP CHANGE THE SNOW OVER TO RAIN LATER TODAY. WE DECIDED TO GO AGAINST THE ADVISORY THIS AFTERNOON SINCE TEMPERATURES SHOULD BE ABOVE FREEZING IN MOST AREAS BEFORE THE ONSET OF THE SNOW LATE THIS AFTERNOON. WE WENT WITH FWC TEMPERATURES SINCE THEY LOOK TO HAVE A GOOD HANDLE ON THE SITUATION.

COX

UPPER LOW OFF CENTRAL COAST STILL NEARLY STATIONARY THIS EVENING. FRONTAL BAND HAS DRAGGED SLOWLY EASTWARD ACROSS SLO/SBA COUNTIES PAST 12 HOURS AS EXPECTED. EASTWARD EXTENT OF THE RAINFALL IS THE SBA/VTU COUNTY BORDER...WITH RAINFALL EXPECTED TO MOVE INTO WESTERN VENTURA COUNTY SHORTLY. AS EXPECTED...RAINFALL AMOUNTS HAVE BEEN FAIRLY IMPRESSIVE ACROSS SBA/SLO COUNTIES...WHERE SOME RAINFALL TOTALS HAVE ALREADY EXCEEDED ONE INCH. FAIRLY STRONG SOUTHERLY LOW LEVEL WINDS STILL EVIDENT ON VANDENBERG VAD WIND PROFILER...WHICH WILL CONTINUE TO KEEP HEAVIER OROGRAPHIC RAINFALL TOTALS ACROSS THE SANTA YNEZ RANGE AND SURROUNDING AREAS.

EXPECT MAIN FRONTAL BAND TO EDGE CLOSER TO THE LA BASIN LATER TONIGHT...WITH MOST OF THE RAIN SATURDAY MORNING AND AFTERNOON. VORTICITY CENTER ROTATING AROUND NORTHWEST SIDE OF UPPER LOW ALSO EXPECTED TO SWING THROUGH AREAS SATURDAY. THIS COMBINED WITH COOLER AIR MOVING IN ALOFT WILL ALLOW FOR THREAT OF SHOWERS AND SLIGHT CHANCE OF THUNDERSTORMS ON SATURDAY. RAINFALL TOTALS EXPECTED TO RANGE FROM ONE TO TWO INCHES ACROSS SAN LUIS OBISPO AND SANTA BARBARA COUNTIES...EXCEPT UP TO 3 INCHES POSSIBLE IN SANTA YNEX MOUNTAINS. ACROSS LA AND VENTURA COUNTIES...ONE HALF TO ONE INCH ACROSS COASTAL AND VALLEYS AREAS...WITH UP TO TWO INCHES POSSIBLE IN THE MOUNTAINS. LATEST ACARS SOUNDINGS STILL SHOWING VERY HIGH FREEZING LEVELS ACROSS LA BASIN...ABOVE 8000 FEET. AS UPPER LOW APPROACHES COAST...SNOW LEVELS AREA EXPECTED TO GRADUALLY LOWER ON SATURDAY. WINTER STORM WATCH STILL IN EFFECT FOR LA AND VENTURA COUNTY MOUNTAINS.

GOMBERG

SHORT TERM DISCUSSION FOR NORTHEAST AND NORTHCENTRAL COLORADO: THE SHORT WAVE DU JOUR HAS INDUCED ENOUGH LIFT TO PRODUCE AREAS OF LIGHT SNOW IN THE PAST HOUR ON THE PLAINS. SATELLITE PICTURES HAVE BEGUN TO SHOW A BIT OF ENHANCEMENT IN THE CLOUD TOPS AS RADAR ECHOES HAVE INCREASED. THE FEATURE IS POORLY HANDLED BY THE MODELS...BUT EMBEDDED IN THE NWLY FLOW AND EXTENDS BACK TO JUST N OF KRWL AT THE PRESENT TIME. ANOTHER SURFACE SURGE APPEARS TO BE WORKING ITS WAY SWD THRU CENTRAL WY. THIS HAS PRODUCED LIGHT SNOW IN KGCC AND COOLED TEMPS IN KSHR AROUND MIDDAY. THE TWO FEATURES COME TOGETHER OVR N-CENTRAL CO BY 06Z OR SO. ACARS SOUNDINGS FM KDEN SHOW THAT 600MB TEMP IS DOWN TO -20C WHICH IS TOO COLD FOR THE GENERATION OF LARGE SNOW CRYSTALS...SO THE SNOW TONIGHT SHOULD STAY ON THE LIGHT AND FLUFFY SIDE. ACCUMULATIONS SHOULD BE IN THE 1 TO 3 INCH RANGE...EVEN IF IT SNOWS FOR 6 OR 8 HOURS. ANOTHER THING TO KEEP AN EYE ON IS THE GRADIENT WINDS ON THE NE PLAINS. KAKO HAS GUSTS UP TO 36 KTS...WITH TEMPS CURRENTLY IN THE MID 20S. AS TEMPS DROP OVERNIGHT AND COOLER AIR FM KCDR MOVES IN...WIND CHILL VALUES SHOULD DROP ENOUGH TO WARRANT A WIND CHILL ADVISORY IN ZONES 48...49...50. SINCE THE SHORT WAVE IS OVR THE MTNS...LIGHT SNOW WL BE LIKELY UP THERE...BUT ONCE AGAIN THE AMS IS SO COOL THAT IT CANNOT SUPPORT HVY ACCUMS. WL NOT HAVE ANY HIGHLIGHTS UP THERE

KDRBY