Area Forecast Discussion
Issued by NWS Hastings, NE

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000
FXUS63 KGID 160934
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
334 AM CST TUE DEC 16 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 334 AM CST TUE DEC 16 2014

WITH LITTLE TO NO RISK OF PRECIPITATION DURING THESE NEXT 24
HOURS...THE MAIN FORECAST CHALLENGE CENTERS AROUND
TEMPERATURES/SKY COVER...AND THE OBVIOUS AFFECT ONE HAS ON THE
OTHER...ALONG WITH ANY INFLUENCE ON TEMPS FROM SNOW COVER IN
NORTHERN/WESTERN COUNTIES.

STARTING OFF WITH THE HERE AND NOW AS OF 0900Z/3AM...ITS
CERTAINLY BEEN A MUCH QUIETER NIGHT THAN THE PRECEDING ONE...AS
ANY MEASURABLE PRECIP ASSOCIATED WITH THE DEPARTING LOW PRESSURE
SYSTEM IS NOW WELL-EAST INTO EASTERN IA. IN THE MID AND UPPER
LEVELS...WATER VAPOR SATELLITE AND SHORT TERM MODEL DATA CLEARLY
DEPICT THE CENTER OF THE CLOSED 500 MILLIBAR LOW OVER NORTHERN
IL...WHILE UPSTREAM FROM IT...THE LEADING EDGE OF A BROAD
SHORTWAVE RIDGE AND ASSOCIATED HEIGHT RISES IS STARTING TO
OVERSPREAD THE LOCAL AREA...WITH THE RIDGE AXIS GENERALLY ALIGNED
NORTH-SOUTH THROUGH THE ROCKIES. FARTHER WEST...THE NEXT BROAD
TROUGH IS IN THE PROCESS OF COMING ONSHORE THE WEST COAST...WHICH
WILL PROVIDE PLENTY OF CHALLENGES LOCALLY IN THE DAYS 2-4 PERIOD
AS COVERED IN THE LONG TERM SECTION BELOW. AT THE
SURFACE...CERTAINLY THE BIG STORY OVERNIGHT HAS BEEN CONTINUED
FAIRLY STRONG NORTHWEST WINDS...ALTHOUGH THEY ARE ON A SLOW-BUT-
STEADY DOWNWARD TREND AS THE PRESSURE GRADIENT STARTS TO RELAX IN
THE WAKE OF THE DEPARTING 1004MB LOW OVER NORTHERN IL...AND AS A
BROAD RIDGE AXIS CENTERED AT AROUND 1030MB OVER THE DAKOTAS/SOUTH
CENTRAL CANADA STARTS TO EXERT INCREASING INFLUENCE LOCALLY. AS OF
THIS TIME HOWEVER...SUSTAINED SPEEDS OF AT LEAST 20-25 MPH ARE
HANGING ON IN EASTERN ZONES WITH HIGHER GUSTS...AND MORE SO 15-20
MPH IN WESTERN ZONES. EARLIER IN THE NIGHT...THERE WERE LAW
ENFORCEMENT REPORTS OF SOME DICEY TRAVEL CONDITIONS DUE TO SLICK
ROADS/LIMITED BLOWING SNOW IN/NEAR THE FAR NORTHERN CWA COUNTIES
OF VALLEY/GREELEY...BUT FORTUNATELY THE DECREASING SPEEDS SHOULD
AT LEAST IMPROVE THIS SITUATION SLIGHTLY. ACTUALLY THE NUMBER ONE
VERY SHORT-TERM CHALLENGE IS SKY COVER...AS WHILE THE MAJORITY OF
THE CWA REMAINS UNDER A BROAD LOW STRATUS DECK AROUND 1500 FT
AGL...AN AREA OF CLEARING HAS RECENTLY BROKEN OUT OVER SOUTHWEST
COUNTIES. TEMP-WISE...AS SUSPECTED 24 HOURS THE COMBO OF CLOUDS
AND/OR BRISK BREEZES IS HOLDING UP THINGS FAIRLY WELL...AND
ALTHOUGH SOME DROPS COULD YET OCCUR AROUND SUNRISE...THINK THE
MAJORITY OF THE CWA SHOULD HOLD UP NO COLDER THAN THE 17-20 RANGE.

LOOKING FORWARD INTO THE DAYTIME FORECAST AND STARTING WITH THE
MID-UPPER LEVEL SCENE...THE AFOREMENTIONED BROAD RIDGE AXIS
OVERSPREADS THE CENTRAL PLAINS BUT FLATTENS A BIT AS IT DOES SO.
AT THE SURFACE...CERTAINLY THE MOST NOTICEABLE CHANGE FROM MONDAY
WILL BE THE DECREASING NORTHWESTERLY WINDS...AS THE PRESSURE
GRADIENT CONTINUES EASING UP AS THE SOUTHERN EDGE OF THE RIDGE
AXIS CENTERED TO THE NORTH CONTINUES PUSHING SOUTHWARD INTO THE
CENTRAL PLAINS IN THE WAKE OF THE DEPARTING LOW THAT REACHES THE
LAKE HURON AREA BY SUNSET. SPEED-WISE...BY MID-DAY SUSTAINED
SPEEDS SHOULD AVERAGE ONLY AROUND 15 MPH IN EASTERN ZONES...AND NO
MORE THAN 10-15 MPH IN WESTERN COUNTIES...AND BY NIGHTFALL THE
ENTIRE CWA SHOULD BE DOWN TO ONLY 5-10 MPH. AS MENTIONED...SKY
COVER/TEMPS ARE REALLY THE FORECAST CHALLENGE OF THE DAY. MODELS
SUCH AS THE 06Z NAM CLEARLY HOLD ONTO PLENTIFUL LOW LEVEL CLOUD
COVER THROUGH THE ENTIRE DAY WITHIN ROUGHLY THE NORTHEAST 1/2 OF
THE CWA...BUT DO SHOW AT LEAST SEVERAL HOURS OF MOSTLY SUNNY-
PARTLY CLOUDY POTENTIAL OVER MUCH OF THE SOUTHWESTERN 1/2.
ALTHOUGH THE LATEST HRRR LOW LEVEL SKY COVER PRODUCT SPORTS A
SIMILAR THEME...IT SUGGESTS THAT SOME OF THE CLEARING THAT OCCURS
COULD FILL BACK IN AS MORE CLOUDS ADVECT IN FROM THE NORTH-
NORTHWEST. EVEN IF PARTS OF THE CWA DO ENJOY APPRECIABLE CLEARING
AND WELCOMED SUNSHINE THROUGH MUCH OF THE DAY...ESPECIALLY THE
LATER AFTERNOON HOURS SHOULD BRING A GRADUAL INCREASE IN MID-HIGH
CLOUDS STREAMING IN FROM THE WEST IN ASSOCIATION WITH A WEAK/LOW
AMPLITUDE SHORTWAVE TROUGH WELL OUT AHEAD OF THE LARGER WESTERN
TROUGH. SO IN SUMMARY...GENERALLY EXPECT MOSTLY CLOUDY SKIES
NORTHEAST 1/2 TODAY...AND MOSTLY SUNNY-PARTLY CLOUDY
SOUTHWEST ESPECIALLY KS ZONES...BUT SOME VARIATION FROM THIS IS
LIKELY AS WELL. OBVIOUSLY THIS TRICKY SKY COVER WILL WORK IN
CONCERT WITH THE GENERALLY 1-3 INCHES OF SNOW COVER IN PLACE OVER
SEVERAL NORTHERN/WESTERN COUNTIES TO MAKE HIGH TEMPS A BIT
CHALLENGING AS WELL. WITH RAW MET/MAV GUIDANCE LOOKING A BIT TOO
COOL ESPECIALLY IN SOUTHERN ZONES...OPTED TO MAKE ONLY MINOR
TWEAKS TO PREVIOUS FORECAST BY TRYING TO STRIKE SOME KIND OF
BALANCE BETWEEN VARIABLE SNOW COVER AND SKY COVER. THE NET
RESULT...ALTHOUGH NOT OVERLY CONFIDENT...YIELDS ONLY MID-UPPER 20S
WITHIN MANY NORTHERN/WESTERN NEB COUNTIES...MAINLY LOW 30S IN
EASTERN/SOUTHERN NEB ZONES...AND GENERALLY MID 30S IN KS ZONES.

TURNING TO THIS EVENING/TONIGHT...THE MID-UPPER LEVEL PICTURE
FEATURES THE AFOREMENTIONED/RATHER SUBTLE LEAD SHORTWAVE
DISTURBANCE CROSSING OVER THE LOCAL AREA...WHILE MORE ENERGETIC
WAVES REMAIN WELL OFF TO THE WEST-SOUTHWEST. MEANWHILE AT THE
SURFACE...THE RIDGE AXIS WILL SLOWLY EDGE EASTWARD. ALTHOUGH WIND
SPEEDS SHOULD REMAIN LIGHT GENERALLY WELL-UNDER 10 MPH THROUGH THE
ENTIRE NIGHT...DIRECTION WILL GRADUALLY TRANSITION FROM NORTHERLY
TO EASTERLY. DESPITE THE FAIRLY WEAK NATURE OF THE PASSING
DISTURBANCE...MODEL RELATIVE HUMIDITY PROGS DEPICT A FAIRLY DECENT
COVERAGE OF MID-HIGH CLOUD COVER THROUGH THE NIGHT...AND HAVE THE
ENTIRE CWA IN PARTLY TO MOSTLY CLOUDY SKY COVER CATEGORY. WHILE
CONFIDENCE IS FAIRLY HIGH IN A PRECIP-FREE NIGHT (ESPECIALLY
MEASURABLE) AND THE OFFICIAL FORECAST REFLECTS SUCH...WOULD NOT BE
TOTALLY SURPRISED TO SEE A WEST-EAST ORIENTED BAND OF FLURRIES
TRY TO GET GOING LATE IN THE NIGHT MAINLY OVER/NEAR THE NORTHERN
CWA IN RESPONSE TO SOME FAIRLY MODEST ISENTROPIC LIFT/FRONTOGENESIS
FOCUSED IN THE ENTRANCE REGION OF A DEPARTING UPPER JET STREAK.
DESPITE THE LIGHT BREEZES...THE EXPECTED FAIRLY HIGH SKY COVER
SHOULD KEEP TEMPS FROM REALLY FALLING OFF...AND AS A RESULT KEPT
LOW TEMPS GENERALLY 2-4 DEGREES ABOVE A 00Z MET/MAV GUIDANCE
BLEND...AIMING MOST OF THE CWA INTO THE 15-20 RANGE...EXCEPT FOR
COLDER READINGS AROUND 10 FAR NORTH. LASTLY...DESPITE FAIRLY HIGH
VALUES OF FORECAST LOW-LEVEL RELATIVE HUMIDITY...CONFIDENCE WAS
NOT SUFFICIENT ENOUGH IN FOG FORMATION TO INTRODUCE EVEN A PATCHY
MENTION FOR LATE TONIGHT...ALTHOUGH 03Z SREF/06Z NAM VISIBILITY
PROGS SUGGEST THAT MAYBE LOCALIZED POCKETS OF MAINLY THE FAR
WESTERN CWA COULD BEAR WATCHING FOR THIS...ESPECIALLY IF ENOUGH
SNOW MANAGES TO MELT TODAY TO ENHANCE LOW-LEVEL MOISTURE.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 334 AM CST TUE DEC 16 2014

THE LONG TERM DISCUSSION WILL BE ADDED HERE WITHIN THE NEXT HOUR
OR SO...STAY TUNED.

&&

.AVIATION...(FOR THE 06Z KGRI/KEAR TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1208 AM CST TUE DEC 16 2014

ALTHOUGH CONFIDENCE IS RATHER HIGH IN BOTH WIND SPEEDS/DIRECTION
AND THE FACT THAT VFR VISIBILITY SHOULD PREVAIL...UNFORTUNATELY
THERE ARE SOME QUESTION MARKS REGARDING CEILING TRENDS...INVOLVING
BOTH WHEN A RETURN TO VFR MIGHT OCCUR AND IF SO FOR HOW LONG. IN
SHORT...OPTED TO ERR A BIT MORE ON THE CAUTIOUS/PESSIMISTIC SIDE
VERSUS PREVIOUS TAF ISSUANCE AND EXTEND AN MVFR CEILING THROUGH
18Z...WITH SOME MODELS/GUIDANCE SUGGESTING THIS MAY BE TOO
LONG...WHILE OTHERS SUGGEST IT MAY NOT BE LONG ENOUGH WITH THE
POTENTIAL FOR MVFR THROUGHOUT THE ENTIRE PERIOD. SO FOR NOW AM
JUST PLAYING A MIDDLE-GROUND. NO MATTER WHAT CEILINGS
DO...CONFIDENCE IS HIGH IN A PRECIPITATION-FREE PERIOD. WIND-
WISE...THINGS START OUT QUITE BRISK EARLY THIS MORNING WITH
SEVERAL MORE HOURS OF NORTHWESTERLY GUST POTENTIAL TO AROUND 30KT
POSSIBLE...ALTHOUGH A SLOW-BUT-STEADY DECREASING TREND WILL TAKE
PLACE DURING THE PERIOD WITH GUST POTENTIAL BY MID-DAY EASING
BELOW 20KT...AND IN FACT FAIRLY LIGHT BREEZES IN PLACE BY TUESDAY
EVENING AS HIGH PRESSURE SETTLES IN.

&&

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

$$

SHORT TERM...PFANNKUCH
LONG TERM...HEINLEIN
AVIATION...PFANNKUCH



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