000
FXUS63 KGID 031638
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
1038 AM CST TUE DEC 3 2013

.UPDATE...
ISSUED AT 1034 AM CST TUE DEC 3 2013

LOTS OF STRATUS CONTINUES TO PUSH SOUTH ACROSS THE FORECAST AREA
THIS MORNING. WITH THIS STATUS MOVING IN...EXPECT TEMPERATURES TO
STRUGGLE TO CLIMB MUCH AFTER THE SKIES CLOUD OVER...AND
CORRESPONDINGLY DROPPED AFTERNOON FORECAST TEMPERATURES
SIGNIFICANTLY ACROSS THE ENTIRE AREA. STUCK FAIRLY CLOSE TO A
BLEND OF PREVIOUS FORECAST AND RAP MODEL...WHICH MAY ACTUALLY BE
TOO OPTIMISTIC FROM AROUND I80 SOUTH TO THE NE/KS STATE LINE...WHERE
STRATUS CONTINUES TO RAPIDLY ENCROACH A BIT FASTER THAN PREVIOUSLY
THOUGHT.

UPDATE ISSUED AT 628 AM CST TUE DEC 3 2013

SENT ANOTHER UPDATE TO LOWER HIGH TEMPS AND HOURLY TEMPS FURTHER
FROM LEXINGTON-ORD IN COORDINATION WITH LBF.

UPDATE ISSUED AT 603 AM CST TUE DEC 3 2013

WITH THE INITIAL FCST ISSUANCE AT 4 AM...WAS UNSURE WHY THE
00Z/06Z NAM TEMPS WERE FCST TO BEHAVE THE WAY THEY WERE DEPICTED
AND NOW IT IS CLEAR AS WE SEE STRATUS SURGING S ACROSS CNTRL NEB.
THE SKY FCST HAS BEEN ENHANCED BY USING THE 13 KM RAP WHICH HAS AN
EXCELLENT HANDLE ON THE STRATUS...EVEN DEPICTING ITS LEADING EDGE
ERODING AROUND MIDDAY. HAVE ALSO REPLACED THE PREVIOUS HIGH TEMP
FCST BY A 50-50 BLEND THE 00Z/06Z NAM 2M TEMPS. THIS HAS COOLED
FCST HIGHS ALONG THE I-80 CORRIDOR NORTHWARD.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 357 AM CST TUE DEC 3 2013

...AN EXTENDED PERIOD OF HARSH WINTER COLD IS ON THE DOORSTEP AND
ONCE IT ARRIVES TONIGHT THERE ARE NO SIGNS OF IT RELEASING UNTIL
MID-MONTH APPROACHES...

ALOFT: THE COLD CORE ARCTIC LOW THAT WAS OVER SIBERIA 7 DAYS AGO
IS NOW ON OUR DOORSTEP /CURRENTLY OVER MT/. WESTERLY FLOW WILL
BECOME SW AS THE LOW BECOMES ELONGATED AND OPENS UP...EJECTING A
SHORTWAVE TROF ACROSS THE NRN PLAINS THIS AFTERNOON AND TONIGHT.

SFC: THE ARCTIC COLD FRONT WAS ALONG THE SD-NEB BORDER...WITH A
PRE-FRONTAL TROF EXTENDING E-W ACROSS NEB. BOTH OF THESE FEATURES
TO PRESS S...CROSSING THE FCST AREA BETWEEN 2 PM AND 8 PM.
BITTERLY COLD HIGH PRES OVER THE CANADIAN ROCKIES BEGINS BUILDING
IN TONIGHT. A LEE-SIDE LOW WILL MIGRATE DOWN THE FRONT RANGE
TODAY AND THEN EJECT ACROSS OK TONIGHT. THIS WILL MAINTAIN A
TIGHT PRES GRADIENT.

HI-RES MESOSCALE MODELS SUGGEST THE FOLLOWING APPROXIMATE TIMES
OF FRONTAL PASSAGE:

3 PM ORD-LEXINGTON
4 PM OSCEOLA-KEARNEY-ELWOOD
5 PM YORK-FRANKLIN-LONG ISLAND KS
6 PM GENEVA-SMITH CENTER KS-PHILLIPSBURG KS
7 PM MANKATO-OSBORNE-STOCKTON
8 PM BELOIT

EARLY THIS MORNING: A BATCH OF MULTI-LAYERED MID-HIGH CLOUDS WAS
MOVING THRU THE FCST AREA. CLOUD TOPS WERE WARMING. UEX/LNX
RADARS HAVE SHOWN SOME SMALL POCKETS OF PRECIP...BUT SUB-CLOUD
AIR IS TOO DRY FOR ANYTHING TO SURVIVE TO THE SURFACE.

TODAY: ONCE THE BATCH OF CLOUDS DEPARTS TO THE E...WE COULD SEE A
PERIOD OF SUBSTANTIAL SUNSHINE. LOOK FOR A RAPID WARM-UP. THIS
WILL BE THE LAST DAY OF MUCH WARMER THAN NORMAL TEMPS. HIGHS ARE
PRIMARILY BASED ON THE 21Z/2 BIAS CORRECTED SREF.

THE SATELLITE FOG/REFLECTIVITY PRODUCT SHOWS STRATUS OVERCAST
IMMEDIATELY BEHIND T HE FRONT. IT IS DISCONCERTING TO SEE IT
DROPPING INTO NRN NEB. THIS WILL NEED TO BE MONITORED AS
SUBSTANTIAL CHANGES WILL NEED TO OCCUR TO THE SHORT-TERM FCST.
THE 06Z NAM SUGGESTS THE STRATUS WILL DROP INTO AREAS N OF HWY
92...BUT THEN GET ERODED BY BOUNDARY LAYER MIXING.

POSSIBLE FCST SHORT-COMINGS: DO WE HAVE THE TIMING OF FRONTAL
PASSAGE CORRECT? THIS WILL HAVE SIGNIFICANT IMPLICATIONS ON THE
FCST. CONFIDENCE IN HOURLY TEMPS AND HIGHS ARE BELOW AVERAGE FROM
HWY 6 NORTHWARD.

IMMEDIATELY BEHIND THE FRONT EXPECT A RAPID INCREASE IN N WINDS
AND IT WILL CONTINUE THRU TONIGHT.

WIND: COOPERATIVE INSTITUTE FOR PRECIP SYSTEMS /CIPS/ TOP 10
ANALOGS OFFER A 50-60% CHANCE OF 30-35 KT WINDS. THE CHANCE FOR
36-40 KTS IS 30-40%. THE 00Z NAM HAS 30 KTS AS LOW AS 1000 FT AT
ORD WITH A MAX OF 32-34 KTS AVAILABLE AT THE TOP OF THE MIXED
LAYER. OVER THE REST OF S-CNTRL NEB 30 KTS IS FCST AS LOW AS 1500
FT WITH 32 KTS MAX. OVER N-CNTRL KS 30 KTS WILL BE AVAILABLE AT
THE TOP OF THE MIXED LAYER /2000 FT/. THIS MATCHES WELL WITH WHAT
IS OFFERED FROM THE CIPS ANALOGS. SO EXPECT THE HIGHEST GUSTS N OF
I-80...BUT THERE IS POTENTIAL FOR EVERYWHERE TO GUST TO 30 KTS
WITH THE HIGHEST PROBABILITY OVER S-CNTRL NEB. 06Z NAM CHECKED. IT
LOOKS A BIT MORE THREATENING WITH MAX GUSTS UP TO 35 KTS N OF HWY
6.

TONIGHT: CLOUDY WITH HARSH N WINDS. LOW TEMPS NEAR NORMAL.

AS FOR PRECIP TODAY-TONIGHT...A SHALLOW FRONTOGENETIC CIRCULATION
WILL NOT BE AIDED BY ANY DEEP-LAYER FORCING/LIFT. AND WHILE THE
LOW-LEVELS AND MID-LEVELS ABOVE 12K FT WILL BE AT OR NEAR
SATURATION ...THE 7-11K FT LAYER WILL BE DRY. SO PLAYED IT AS A
SLIGHT CHANCE FOR A LITTLE LIGHT RAIN/SNOW N OF HWY 92 LATE THIS
AFTERNOON AND A SLIGHT CHANCE OF LIGHT SNOW TONIGHT. BY 09Z...THE
BASE OF THE STRATUS WILL BECOME COLD ENOUGH FOR ICE TO FORM IN-
CLOUD. SO A SLIGHT CHANCE OF FLURRIES WAS INCLUDED FROM HWY 92
DOWN TO HWY 6 LATE TONIGHT.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 357 AM CST TUE DEC 3 2013

GUIDANCE SUGGESTS A MID TO UPPER LEVEL LONG WAVE TROUGH WILL
EXTEND FROM CENTRAL CANADA...SOUTHWEST INTO THE WESTERN CONUS AT
12Z WEDNESDAY. THIS LONG WAVE TROUGH IS EXPECTED TO PERSIST OVER
THE SAME AREAS THROUGH 12Z FRIDAY...AT WHICH TIME IT SHOULD MOVE
EAST/NORTHEAST AND WEAKEN. A SECOND MID TO UPPER LEVEL LONGWAVE
TROUGH IS THEN EXPECTED TO DEVELOP OVER THE WESTERN CONUS SATURDAY
INTO SATURDAY NIGHT AND PERSIST THROUGH THE END OF THE LONG TERM
FORECAST PERIOD. RESULTANT MID TO UPPER LEVEL FLOW OVER OUR AREA
IS EXPECTED TO REMAIN FROM THE SOUTHWEST 12Z WEDNESDAY THROUGH 12Z
FRIDAY...WITH QUASI-ZONAL FLOW EXPECTED FRIDAY INTO FRIDAY
NIGHT...AND SOUTHWEST FLOW ONCE AGAIN SATURDAY THROUGH THE END OF
THE LONG TERM FORECAST PERIOD. A CLOSED MID LEVEL LOW...EMBEDDED
WITHIN THE FIRST LONG WAVE TROUGH...IS EXPECTED OVER THE NORTHERN
PLAINS AT 12Z WEDNESDAY...WITH THIS MID LEVEL LOW EXPECTED TO
EJECT TO THE NORTHEAST...AWAY FROM THE LONG WAVE TROUGH...INTO
ONTARIO AND QUEBEC BETWEEN 12Z WEDNESDAY AND 12Z FRIDAY. A
SECONDARY MID LEVEL LOW IS ALSO EXPECTED TO MOVE SOUTH AND THEN
EAST FROM SASKATCHEWAN INTO THE NORTHERN PLAINS BETWEEN 12Z
WEDNESDAY AND 12Z FRIDAY. THIS SECONDARY MID LEVEL LOW IS THEN
EXPECTED TO MOVE EAST/NORTHEAST INTO THE UPPER MISSISSIPPI VALLEY
AND ONTARIO...ALONG WITH THE LONG WAVE TROUGH...FRIDAY INTO FRIDAY
NIGHT. THERE ARE THEN INDICATIONS OF A MID LEVEL SHORTWAVE
EJECTING FROM THE WESTERN CONUS AND MOVING EAST ACROSS PORTIONS OF
THE CENTRAL AND SOUTHERN PLAINS ON SUNDAY. AT THE SURFACE AN AREA
LOW BAROMETRIC PRESSURE IS EXPECTED OVER THE UPPER MISSISSIPPI
VALLEY AT 12Z WEDNESDAY...WITH AN ASSOCIATED LOW LEVEL BAROCLINIC
ZONE EXTENDING SOUTH/SOUTHWEST FROM THE LOW INTO THE MID
MISSISSIPPI VALLEY AND SOUTHERN PLAINS. STRONG SURFACE RIDGING
SHOULD BE WORKING INTO THE CENTRAL PLAINS ON WEDNESDAY AS THE
FIRST MID LEVEL LOW AND SURFACE LOW DEPART TO THE NORTHEAST. THE
SURFACE RIDGE SHOULD THEN PERSIST ACROSS THE CENTRAL PLAINS
THROUGH FRIDAY AS THE SECONDARY MID LEVEL LOW ADVANCES SOUTH AND
THEN EAST FROM SASKATCHEWAN...INDUCING A WEAK AREA OF LOW
BAROMETRIC PRESSURE AT THE SURFACE ACROSS PORTIONS OF THE UPPER
MISSISSIPPI VALLEY. LEE SIDE TROUGHING ALONG THE FRONT RANGE IS
THEN EXPECTED TO DEVELOP FRIDAY NIGHT INTO SATURDAY.
FINALLY...THERE IS A LIKELIHOOD A SURFACE LOW WILL MOVE EAST
SOMEWHERE ACROSS THE CENTRAL AND/OR SOUTHERN PLAINS DURING THE DAY
SUNDAY AS THE MID LEVEL SHORTWAVE DOES THE SAME. GIVEN ALL
THIS...LOW LEVEL FLOW SHOULD REMAIN FROM THE NORTH/NORTHWEST
WEDNESDAY FRIDAY...WITH SOUTHERLY FLOW EXPECTED SATURDAY...AND
ANOTHER ROUND OF NORTHWESTERLY LOW LEVEL FLOW TOWARDS THE END OF
THE FORECAST PERIOD.

ALTHOUGH THERE COULD BE A WEAK RIBBON OF MID LEVEL THERMAL
ADVECTION GRAZING OUR NORTHWEST DURING THE DAY WEDNESDAY...AT THIS
TIME IT APPEARS ANY SUBSTANTIAL OMEGA WILL REMAIN RELEGATED
NORTH/NORTHEAST AND WEST OF OUR AREA...EITHER IN CLOSER PROXIMITY
TO THE DEPARTING MID LEVEL LOW TO OUR NORTH/NORTHEAST OR IN CLOSER
PROXIMITY TO THE LONGWAVE TROUGH AXIS TO OUR WEST. WENT AHEAD WITH
DRY CONDITIONS ON WEDNESDAY AS A RESULT. HEADING INTO WEDNESDAY
NIGHT...THERE ARE INDICATIONS OF A ~90KT MID LEVEL JET STREAK
MOVING INTO THE MID MISSISSIPPI VALLEY...WITH THE RIGHT-REAR
QUADRANT OF THIS STREAK PERHAPS GENERATING ENOUGH OF A DIRECT
THERMAL CIRCULATION AND RESULTANT OMEGA FOR PRECIPITATION
PRODUCTION ACROSS PORTIONS OF OUR CWA. QPF FIELDS FROM THE
NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL SEEM TO SUGGEST OUR
WEST/SOUTHWEST CWA STAND THE BEST CHANCE AT OBSERVING MEASURABLE
PRECIPITATION. AS A RESULT...WENT AHEAD WITH ~20% POPS ACROSS OUR
WEST/SOUTHWEST 00Z-06Z THURSDAY. IT APPEARS THE MID LEVEL JET
STREAK WILL PERSIST THURSDAY INTO THURSDAY NIGHT AS WELL...HOWEVER
IT ALSO APPEARS THE JET STREAK AXIS WILL SHIFT EAST/SOUTHEAST
SOMEWHAT...THUS POSITIONING THE RIGHT-REAR QUADRANT AND RESULTANT
OMEGA SLIGHTLY SOUTH/SOUTHEAST OF OUR AREA AS WELL. ALTHOUGH SOME
GUIDANCE SUGGESTS OUR EXTREME SOUTH COULD OBSERVE MEASURABLE
PRECIPITATION AT ONE TIME OR ANOTHER THURSDAY AND THURSDAY
NIGHT...THERE REALLY IS NO AGREEMENT BETWEEN THE MODELS AS TO
WHETHER THIS WILL OCCUR THURSDAY...THURSDAY NIGHT...OR AT ALL.
ALTHOUGH WE PROBABLY CANNOT COMPLETELY RULE OUT A PERIOD OF VERY
LIGHT PRECIPITATION AT SOME POINT DURING THE THURSDAY-THURSDAY
NIGHT TIME PERIOD...GIVEN THE PRIMARY AXIS OF OMEGA APPEARS TO
REMAIN SOUTH/SOUTHEAST OF OUR AREA AND THE VERY LOW CONFIDENCE
THAT ANYONE WOULD ACTUALLY OBSERVE MEASURABLE
PRECIPITATION...OPTED TO REMOVE MEASURABLE PRECIPITATION FROM THE
THURSDAY-THURSDAY NIGHT TIME PERIOD AND INSTEAD GO AHEAD WITH A
MENTION OF SNOW FLURRIES. THE APPROACH OF THE MID LEVEL SHORTWAVE
SUNDAY COULD THEN BRING A CHANCE FOR PRECIPITATION SUNDAY.
ALLBLEND RESPONDED BY PROVIDING ~30% POPS TO THE AREA AND THESE
POPS WERE LEFT UNCHANGED FOR THE MOST PART.

FORECAST PROXIMITY SOUNDINGS FROM ACROSS THE CWA...PER THE NAM
AND OPERATIONAL GFS...SUGGEST AN INVASION OF ARCTIC AIR WILL KEEP
THE LOWER TROPOSPHERE COLD ENOUGH FOR SNOW PRODUCTION DURING THE
LONG TERM FORECAST PERIOD. ANY SNOWFALL THAT IS REALIZED ACROSS
OUR CWA WEDNESDAY NIGHT INTO THURSDAY SHOULD REMAIN VERY LIGHT.
THAT BEING SAID...THE VERY COLD/DRY LOWER TROPOSPHERE SUGGESTS
SNOW-WATER RATIOS WILL BE VERY HIGH...SOMEWHERE IN 20-30:1
RANGE...THUS EVEN A COUPLE HUNDREDTHS OF AN INCH OF LIQUID
PRECIPITATION...WHICH IS FORECAST ACROSS OUR WEST/SOUTHWEST 00-06Z
THURSDAY...COULD BE CAPABLE OF PRODUCING ~0.5" OF SNOWFALL. THE
MID LEVEL SHORTWAVE WHICH COULD POTENTIALLY IMPACT OUR AREA NEXT
SUNDAY IS SLIGHTLY MORE INTERESTING...WITH THE OPERATIONAL GFS AND
EC BOTH SUGGESTING SNOWFALL ACCUMULATION IN EXCESS OF AN INCH WILL
BE REALIZED ACROSS THE CWA. CERTAINLY SOMETHING TO CONTINUE
MONITORING.

ARCTIC AIR REMAINS POISED TO OCCUPY THE CENTRAL PLAINS DURING THE
LONG TERM FORECAST PERIOD. TEMPERATURES WITHIN THE SOURCE REGION
OF THE ARCTIC AIRMASS...CURRENTLY ACROSS PORTIONS OF
ALBERTA...SASKATCHEWAN AND MANITOBA...ONLY CLIMBED INTO THE TEENS
AND 20S MONDAY AFTERNOON...AND THESE VALUES ARE ALSO BEING
PRESENTED TO OUR AREA BY MULTIPLE SETS OF GUIDANCE THURSDAY
ONWARD. WEDNESDAY MAY ACTUALLY BE A TOUCH WARMER AS THE TRUE MASS
OF ARCTIC AIR WILL TAKE SOME TIME TO WORK INTO THE REGION...THUS
WEDNESDAY AFTERNOON HIGHS RANGING FROM THE 20S TO NEAR 30 ARE
FORECAST. BASED ON THE SOURCE REGION OF THE INCOMING ARCTIC AIR
MASS...IT APPEARS LIKELY OVERNIGHT LOWS IN THE SINGLE DIGITS WILL
ALSO BE COMMON THURSDAY ONWARD.

FINALLY...LATEST GUIDANCE SUGGESTS A SUSTAINED LOW LEVEL WIND
FIELD AT AROUND 15KTS...WORKING IN CONCERT WITH THE AFOREMENTIONED
SINGLE DIGIT OVERNIGHT LOWS...WILL PROVIDE APPARENT TEMPERATURE
VALUES BETWEEN -15 AND -19 DEGREES F ACROSS NORTHWESTERN PORTIONS
OF OUR CWA WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING. WILL GO
AHEAD AND OUTLOOK THESE CONDITIONS IN THE HWO...PRIMARILY FOR
LOCATIONS ALONG AND NORTHWEST OF A LINE OF LEXINGTON...TO LOUP
CITY AND GREELEY. ALTHOUGH THESE VALUES DO NOT JUSTIFY ADVISORY
ISSUANCE...THIS WILL CERTAINLY NEED TO BE MONITORED THROUGH THE
NEXT COUPLE DAYS IN CASE HEADLINES BECOME NECESSARY. ALTHOUGH NOT
AS WIDESPREAD...APPARENT TEMPERATURE VALUES ARE ALSO FORECAST TO
APPROACH -15 DEGREES F ACROSS VALLEY AND GREELEY COUNTIES EARLY
FRIDAY MORNING AS WELL.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 603 AM CST TUE DEC 3 2013

TODAY: FOG/REFLECTIVITY SATELLITE IMAGERY SHOWS IFR STRATUS IS
SURGING S TOWARD GRI AT 12Z. ODX IS NOW OVC008 AND HAVE TIMED
THIS INTO GRI AT 14Z. THE STATISTICAL MODEL OUTPUT IS NOT HANDLING
THIS STRATUS. SO THIS FCST IS BASED ON CURRENT TRENDS AND MODEL RH
FIELDS...WHICH INDICATE THE LEADING EDGE OF THE STRATUS COULD
BEGIN ERODING AROUND MIDDAY...ALLOWING FOR A COUPLE HRS OF VFR
CIGS. IF THIS OCCURS...STRATUS WILL RE-INVADE AROUND 21Z WITH
FRONTAL PASSAGE. SHOULD SEE A SIGNIFICANT INCREASE IN N WINDS...
BUT THERE IS UNCERTAINTY ON IF ITS GRADUAL OR ABRUPT. CONFIDENCE:
AVERAGE

TONIGHT: STATISTICAL MODEL OUTPUT SUGGESTS MVFR CIGS...BUT CURRENT
OBS UPSTREAM ARE LARGELY IFR. THE TAF CIG IS MORE PESSIMISTIC THAN
MOS BUT NOT AS PESSIMISTIC AS CURRENT OBS UPSTREAM. BE AWARE THAT
CIGS MAY NEED TO BE DOWNGRADED A CATEGORY LATER TODAY. CONFIDENCE:
AVERAGE.


&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&

$$

UPDATE...ROSSI
SHORT TERM...HALBLAUB
LONG TERM...BRYANT
AVIATION...HALBLAUB