Area Forecast Discussion
Issued by NWS Hastings, NE

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000
FXUS63 KGID 252358
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
558 PM CST THU DEC 25 2014

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 357 PM CST THU DEC 25 2014

AS A COLD FRONT TRANSITIONS THROUGH THE REGION TODAY...EXPECT CLOUD
COVER TO INCREASE AND THE POTENTIAL FOR ACCUMULATING SNOWFALL FOR
MUCH OF THE CWA. CONSEQUENTLY...A WINTER WEATHER ADVISORY WILL BE IN
EFFECT FOR OUR WESTERN AND NORTHWESTERN COUNTIES. THE ADVISORY WILL
BE FOR SNOWFALL AMOUNTS NEAR ONE TO THREE INCHES THROUGH TOMORROW
NIGHT.

AT 21Z...A COLD FRONT WAS LOCATED JUST TO OUR NORTH BEGINNING
TO PASS THROUGH ORD...WITH SNOWFALL ONGOING ACROSS THE NEBRASKA
PANHANDLE. EXPECT THIS COLD FRONT TO CONTINUE PUSHING SOUTH
THROUGHOUT THE DAY AND EVENING. BY FRIDAY MORNING...THE COLD FRONT
WILL HAVE MADE ITS WAY COMPLETELY THROUGH THE CWA...AND SNOWFALL
SHOULD BEGIN ACROSS WESTERN PARTS OF THE OUTLOOK AREA.

WITH THE ABSENCE OF A STRONG SURFACE LOW/MID LEVEL LOW...SNOWFALL
SHOULD BE PRETTY CONSISTENT DURING THE EVENT BEING DRIVEN PRIMARILY
BY AN UPPER LEVEL WAVE. MEANING...CHANCES FOR SNOW BANDING TO OCCUR
IS LIMITED UNDER THESE CIRCUMSTANCES. HOWEVER...CONFIDENCE IS HIGH
REGARDING OVERALL SNOW POTENTIAL AND LEANED TOWARDS WPC FOR
QPF...WHICH RESULTED IN TOTAL AMOUNTS RANGING AROUND 0.10 AND 0.25
INCHES. SEVERAL SETS OF GUIDANCE INDICATED QPF AROUND THESE VALUES.
THE SREF PROBABILITY ENSEMBLE FOR 0.25 INCHES OR GREATER WAS NEAR
60%-80% THROUGH FRIDAY NIGHT ACROSS OUR WEST...WHICH FURTHER LEAD TO
HIGH CONFIDENCE IN REGARDS TO QPF. UNDER A COLD ATMOSPHERIC
PROFILE...I BASICALLY USED A 15 TO 1 SNOWFALL RATIO FOR
COLLABORATION PURPOSES...BUT SERIOUSLY CONTEMPLATED A HIGHER RATIO
NEAR 20 TO 1. THERE ARE DECENT OMEGA VALUES IN PLACE WITHIN A MOIST
DGZ LAYER. THREE INCHES OF SNOWFALL IS EXPECTED ALONG AND NORTH
OF A LINE FROM ROUGHLY BEAVER CITY...TO KEARNEY...TO GREELEY. I
WOULD NOT BE SURPRISED IF MORE COUNTIES WERE ADDED EASTWARD INTO
THE ADVISORY OVER THE NEXT COUPLE OF SHIFTS. FRIDAY NIGHT WE LOSE
ALL FORCING AND MOISTURE...SO SNOWFALL SHOULD END SOUTHWEST TO
NORTHEAST BY THIS TIME.

BEHIND THE COLD FRONT...HIGHS TOMORROW WILL BE DRASTICALLY DIFFERENT
THAN WHAT WE EXPERIENCED TODAY. HIGHS WILL BE IN THE MID TO UPPER
20S FOR MOST OF THE OUTLOOK AREA...WITH PERHAPS SOME KANSAS COUNTIES
REACHING THE LOWER 30S TOMORROW AFTERNOON. THESE TEMPERATURES WILL
NOT FLUCTUATE MUCH FROM LOWS TONIGHT. OVERCAST SKIES WILL KEEP
TEMPERATURES PRETTY STEADY FROM TONIGHT THROUGH TOMORROW.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 357 PM CST THU DEC 25 2014

ALOFT: THE PRIMARY SHORTWAVE TROF WILL LIFT NE OUT OF THE WRN USA
LONGWAVE TROF AND CROSS KS/NEB FRI NIGHT. THIS TROF WILL BE SHEARED
AND WEAKENING WITH NO CLOSED CIRCULATION ALOFT. THE TROF HEADS FOR
THE GREAT LAKES SAT WITH BROAD/FLAT FLOW LEFT BEHIND OVER THE REGION
INTO SUN. MEANWHILE...THE NEXT SHORTWAVE TROF WILL DIVE INTO THE WRN
USA SUN-MON AND CLOSE OFF OVER THE DESERT SW. MEAN WESTERLY FLOW
OVER THE CNTRL PLAINS WILL BECOME NW BY MID-WEEK WITH CONFLUENT FLOW
DOWNSTREAM.

WINTER COLD: THE PATTERN IS LOOKING COLDER...FAVORING BELOW NORMAL
TEMPS THE NEXT 10 DAYS....AND 2-3 DAYS OF MUCH BELOW AS A RIDGE
BUILDS OVER AK AND UNLOADS SIGNIFICANT ARCTIC COLD INTO THE USA.
MULTI-DAY EC/GFS/GEM ENSEMBLE MEANS CONT IN UNISON WITH A STRONG
SIGNAL...A +TILT LONGWAVE TROF FROM HUDSON BAY SW INTO THE WRN USA.
THE INITIAL PUSH INTO THE WRN USA GUARANTEES TEMPS WILL PLUMMET IN
THE 12/29-1/1 TIME FRAME. THEREAFTER...THE TRACK OF THE ALBERTA
CLIPPERS WILL DETERMINES IF THE COLD EASES AND WE REMAIN ON ITS WRN
FRINGE IN DOWNSLOPE FLOW. THERE ARE SIGNS THE AK RIDGE WILL BE
UNDERCUT BY THE WESTERLIES.

SURFACE: CANADIAN HIGH PRES WILL CONT TO SLIDE SE OVER THE PLAINS
FRI NIGHT AND WILL BE OVERHEAD SAT. IN THE MEANTIME...AN ARCTIC COLD
FRONT WILL PRESS S...ARRIVING AT THE NRN USA BORDER AT DAWN SUN.
THIS FRONT WILL SWEEP THRU HERE LATE SUN NIGHT WITH ARCTIC HIGH PRES
SLIDING DOWN THE FRONT RANGE BEHIND. THIS HIGH WILL BE OVERHEAD TUE
AND SLIP S WED WITH DOWNSLOPE W FLOW DEVELOPING. ANOTHER ARCTIC
FRONT WILL DROP INTO THE NRN USA THU. THIS NEXT SURGE OF FRIGID AIR
WILL PROBABLY MAKE IT IN HERE LATE NEXT WEEK.

THE DAILY DETAILS...

FRI EVE: LIGHT SNOW WILL BE IN PROGRESS ACROSS THE ENTIRE FCST AREA
AT SUNSET AND WILL GRADUALLY END FROM SW-NE.

BELIEVE WE`RE LOOKING AT A 7-10 HR PERIOD OF SNOW AT ANY ONE
LOCATION. IT ENDS FIRST OVER N-CNTRL KS...BY MIDNIGHT. THEN OVER S-
CNTRL NEB 12AM-4AM.

THE GREATEST LIFT WILL OCCUR THE FRONT HALF OF THE EVENT AND WILL BE
DONE BY 02Z AND THAT MEANS THE GREATEST ACCUMS WILL OCCUR BEFORE
THEN. SO WHILE SNOW WILL LINGER INTO THE NIGHT...THERE WILL BE
LITTLE ADDITIONAL ACCUM AFTER 8 PM.

SNOWFALL: THE INGREDIENTS JUST ARE NOT THERE FOR THIS TO AMOUNT TO
MUCH. NO WARM AIR ADVECTION OR CLOSED MID-LVL LOW AND DEFORMATION.
THIS IS PRIMARILY DRIVEN BY THE APPROACHING TROF AND A SUBTLE JETLET
OUTSIDE THE MAIN CORE OF THE UPR JET. BELIEVE AN ADVISORY WILL
HANDLE IT. WENT A LITTLE BELOW WPC QPF WHICH PAINTED A SWATH OF 1-3"
ACROSS THE FCST AREA WITH THE HIGHEST AMOUNTS N AND W OF THE TRI-
CITIES.

CURRENT EXPECTATIONS...

LESS THAN 2" PLAINVILLE KS-HEBRON NEB-YORK
2-3" ALMA-HASTINGS-FULLERTON
AROUND 3" BEAVER CITY-LEXINGTON/KEARNEY-ORD/GREELEY

MAIN AXIS: MULTI-MODEL CONSENSUS AND THE PAST SEVERAL RUNS OF THE
SREF MEAN HAVE THE AXIS OF GREATEST SNOWFALL/QPF FROM IMPERIAL-
BROKEN BOW-O`NEILL. THE SRN FRINGE OF THIS SHOULD BRUSH DAWSON/
SHERMAN/VALLEY COUNTIES.

SNOW RATIO: USED 13-17:1 00Z-06Z WITH THE HIGHER VALUES N AND W OF
THE TRI-CITIES. THIS IS A 6-HR AVERAGE WHICH SHOULD HANDLE THE
DECREASING LIFT IN THE IDEAL SNOW GROWTH ZONE...AND WHAT LIFT IS
FCST PRIMARILY ABOVE THAT LEVEL. AFTER 06Z USED 8-10:1 AS THE
QUALITY OF THE FLAKES WILL BE POOR FOR ACCUM.

THE MID SHIFT WILL NEED TO MONITOR TRENDS IN VERTICAL MOTION FOR
POSSIBLE CHANGES TO SLR`S AND POSSIBLE ADJUSTMENTS TO ACCUM. WOULD
NOT BE SURPRISED TO SEE 20:1 ON THE NW FRINGE OF THE FCST AREA. THE
TEMP PROFILE IS FAIRLY COLD /NEAR -10C IN THE LOWEST 12K FT/.

SAT: CLEARING. HIGH TEMPS BELOW AVERAGE CONFIDENCE AS FRESH SNOW
WILL BE ON THE GROUND. MODELS DO NOT HANDLE THIS WELL AND IT IS
TOUGH TO ACCOUNT FOR. WE CURRENTLY HAVE 23-30F BUT BELIEVE WE COULD
BE 3-5F TOO COLD.

SUN: MULTI-LAYERED MID-HIGH CLOUDS. BELIEVE IT ENDS UP M/CLOUDY AND
WE ARE PROBABLY NOT PESSIMISTIC ENOUGH IN THE FCST JUST YET. AGAIN
HIGHS ARE BELOW AVERAGE CONFIDENCE.

MON: COLD AIR ADVECTION. BLUSTERY/CLOUDY/MUCH COLDER WITH N WINDS
GUSTING 25-30 MPH. POSSIBLY SOME FLURRIES OR BRIEF SNOW SHWRS.

TUE: BITTERLY COLD. WE CONT TO SEE POTENTIAL FOR HIGHS IN THE SINGLE
DIGITS /OVER S-CNTRL NEB/ IN THE MODELS THAT HANDLE EXTREME COLD THE
BEST. THE FCST CONTS TO TREND COLDER.

WED: QUIET AND DRY. STILL VERY COLD.

THU: QUIET AND DRY. TEMPS SHOULD TEMPORARILY RETURN TO NEAR NORMAL
/30S/.

LOTS OF UNCERTAINTY IN WHEN THE NEXT ARCTIC COLD FRONTAL PASSAGE
OCCURS...BUT THE PATTERN FAVORS MORE ARCTIC INTRUSIONS.&&

.AVIATION...(FOR THE 18Z KGRI/KEAR TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1136 AM CST THU DEC 25 2014

EXPECT VFR CONDITIONS THROUGH MID TO LATE AFTERNOON TODAY. A COLD
FRONT WILL TRANSITION THROUGH THE REGION LATER TODAY...RESULTING
IN A NORTHERLY WIND SPEED BEHIND THE FRONT AROUND 15 KNOTS...AND
AN INCREASE IN CLOUD COVER AS WELL. CEILINGS WILL BEGIN TO
DEGRADE LATE THIS AFTERNOON AND WILL TRANSITION TO MVFR
CONDITIONS FOR AT LEAST THE REMINDER OF THIS TAF PERIOD. ALTHOUGH
TOO EARLY TO ENTER INTO THIS TAF ISSUANCE...CONFIDENCE FOR IFR
CONDITIONS AND SNOWFALL ARE LOOKING LIKELY BY AT LEAST FRIDAY
AFTERNOON...PERHAPS AS EARLY AS LATE FRIDAY MORNING. DURING THIS
TIME VISIBILITY MAY BE AROUND 1 MILE AND CEILINGS LOOK TO BE
AROUND 1000 FEET. AGAIN...TOO EARLY FOR THIS TAF...BUT ANTICIPATE
THESE CHANGES OR SOMETHING SIMILAR IN THE COMING TERMINAL
FORECASTS.

&&

.AVIATION...(FOR THE 00Z KGRI/KEAR TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 554 PM CST THU DEC 25 2014

STRATUS AND EVENTUALLY SNOW WILL LIKELY MOVE IN BY FRIDAY.
CONFIDENCE IS LOW REGARDING HOW SOON ANYTHING MORE THAN FLURRIES
WILL OCCUR. THIS WILL MOST LIKELY HAPPEN TOWARD MID-AFTERNOON
FRIDAY. CONFIDENCE IS LOW WITH VISIBILITY ON FRIDAY AFTERNOON AS
WELL. STRATUS SEEMS TO HAVE STALLED A BIT JUST SOUTH OF ORD...BUT
THE INTRODUCTION OF MVFR CEILINGS NEAR 07Z MIGHT BE TOO LATE IF A
PUSH SOUTH RESUMES.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY FROM 9 AM FRIDAY TO MIDNIGHT CST FRIDAY
     NIGHT FOR NEZ039-040-046-047-060-061-072-073-082.

KS...NONE.
&&

$$

SHORT TERM...GUERRERO
LONG TERM...HALBLAUB
AVIATION...HEINLEIN



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