Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 141045
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
545 AM CDT MON APR 14 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 438 AM CDT MON APR 14 2014

THE MAIN FOCUS IN THE SHORT TERM WILL BE A CHANCE OF LIGHT
PRECIPITATION AS A RESULT OF STEEP LAPSE RATES AND THE PASSING
LONGWAVE TROUGH AXIS. TEMPERATURES WILL BE DIFFICULT TO DETERMINE
AS THIS DEPENDS ON SNOW COVER AND HOW MUCH SUN BREAKS
OUT...ESPECIALLY TO THE WEST/NORTHWEST WHERE MORE SNOW FELL
YESTERDAY. I ACTUALLY LOWERED TEMPERATURES A BIT MORE IN THE
NORTH. WINDS HAVE STAYED IN THE WIND ADVISORY RANGE FOR AT LEAST
PART OF THE CWA FOR THE OVERNIGHT HOURS...THIS HAS CAUSED SOME
ISSUES FOR BLOWING SNOW...SO I HAVE INCLUDED THIS IN THE FORECAST
THROUGH MID-MORNING. THE LOWEST VISIBILITY SO FAR TONIGHT ON
ASOS/AWOS SITES HAS BEEN 3 MILES. THE WIND SHOULD SUBSIDE A BIT BY
LATE MORNING BUT STILL BE ELEVATED AS THE SURFACE PRESSURE
GRADIENT IS SLOW TO RELAX. WENT WITH SIMILAR LOWS FOR
TONIGHT...BUT A BIT LOWER FOR SOME SPOTS AS THE SURFACE HIGH
BUILDS IN AND WIND SETTLES DOWN.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 438 AM CDT MON APR 14 2014

WINTRY WX IS NOT DONE YET AS MORE ACCUMULATING SNOW LOOKS POSSIBLE
FOR PARTS OF THE FCST AREA WED NIGHT INTO THU. PRELIMINARY TAKE ON
THIS SUGGESTS THE GREATEST AMOUNTS WOULD BE OVER N-CNTRL KS INTO
THAYER/NUCKOLLS COUNTIES.

ALOFT: AS OF THIS MORNING...A LONGWAVE TROF WAS OVER CNTRL N AMERICA
WITH A HIGHLY AMPLIFIED RIDGE ALONG THE W COAST AND A MODERATE
AMPLITUDE RIDGE OVER THE WRN ATLANTIC. WATER VAPOR IMAGERY SHOWED A
SHORTWAVE TROF APPROACHING BRITISH COLUMBIA. THIS TROF WILL MOVE
ONSHORE TONIGHT...MOWING DOWN THE RIDGE W COAST RIDGE. A SHORTWAVE
RIDGE WILL SLIDE THRU HERE TUE FOLLOWED BY THAT SHORTWAVE TROF WED.
THIS WILL RESULT IN RE-AMPLIFICATION OF THE CNTRL N AMERICA TROF
INTO THU WITH HEIGHTS BUILDING AGAIN OVER THE WRN USA. THE PAST TWO
CYCLES OF MODEL RUNS AND THE 12Z EC ENSEMBLE MEAN FCST THE TROF TO
SHIFT INTO THE MS VALLEY FRI...WITH NW FLOW DEVELOPING HERE.
POTENTIAL FCST PROBLEMS LIE IN WAIT WED-THU AS MODEL/ENSEMBLE SPREAD
REMAINS WITH THE DETAILS OF HOW THE BASE OF TROF EVOLVES.

WHILE THE INITIAL TROF MOVES THRU WED /PRIMARILY OVER THE NRN
PLAINS/...A 120 KT JET STREAK WILL BE CARVING OUT A NEW LONGWAVE
TROF WED NIGHT...WITH A SHORTENING WAVELENGTH. THIS WILL INDUCE
MODEST CYCLOGENESIS THU ALONG THE FRONT THAT MOVES THRU HERE WED. A
COUPLE JET STRUCTURE DEVELOPS THU AND LOOKS THREATENING FOR WINTRY
WX.

THE 12Z EC MEAN HAS ANOTHER TROF MOVING INTO THE NRN PLAINS SAT WITH
NW FLOW AND RISING HEIGHTS IN ITS WAKE SUN. WE DO NEED TO WATCH THE
TROF THAT WILL BE EJECTING OUT OF THE DESERT SW SAT-SUN. AT THE
LEAST IT WILL INCREASE CLOUDS AND COULD BRING SOME LIGHT RAIN.

SURFACE: THE WARM SECTOR DEVELOPS TUE AS A CLIPPER LOW DIVES INTO
SD. ITS COLD FRONT WILL PRESS THRU THE AREA WED AS THE LOW HEADS FOR
WI AND EVENTUALLY THE GREAT LAKES BY DAWN THU. ANOTHER SURGE OF
UNSEASONABLY COLD AIR WILL SPILL INTO THE REGION AND THIS COULD
SPELL TROUBLE AS THE JET STREAK/FALLING HEIGHTS INDUCE CYCLOGENESIS
THU INTO THU NIGHT. THIS LOW WILL RIDE UP THE FRONT AND WILL BE OVER
MO BY DAYBREAK FRI. SRN CANADA HIGH PRES BUILDS IN FRI AND SLIPS E
OF THE REGION SAT...WITH RETURN FLOW AND RENEWED LEE-SIDE TROFFING
DEVELOP. A POSSIBLE SNAG NEXT WEEKEND IS THE POTENTIAL FOR CLOUDS
AND SOME LIGHT PRECIP.

HAZARDS: CRITICAL OR NEAR CRITICAL FIRE WX STILL EXPECTED TOMORROW.
HELD OFF ON A FIRE WX WATCH DUE TO LINGERING UNCERTAINTY ON
DEWPOINTS. I WANT TO GIVE THE DAY SHIFT A CHANCE TO RE-EVALUATE.

ACCUMULATING SNOWFALL IS NOW OUTLOOKED FOR WED NIGHT-THU...PRIMARILY
S AND E OF THE TRI-CITIES. THERE IS POTENTIAL FOR 3-5 INCHES OF WET
SNOW...POSSIBLY MORE.

FCST CONFIDENCE IS AVERAGE TUE-FRI AND BELOW AVERAGE SAT-SUN.

THE DAILY DETAILS...

TUE: SUBSTANTIAL IMPROVEMENT. TEMPS ROCKET BACK CLOSE TO NORMAL BUT
WITH SW WINDS GUSTING 30-35 MPH. HIGH CLOUDS WILL BEGIN TO INVADE IN
THE AFTERNOON.

USED THE CONSENSUS OF MODEL 2M TEMPS FOR HIGHS WHICH INCORPORATES AS
SWATH OF RELATIVELY COOLER TEMPS N AND W OF THE TRI-CITIES WHERE THE
GREATEST SNOW FELL.

WED: COLD FRONTAL PASSAGE...BUT THE COLDEST AIR WILL NOT ARRIVE
UNTIL WED NIGHT. FAIRLY CLOUDY. CANT RULE OUT A FEW SPRINKLES N OF I-
80 BUT IT`S NOT IN THE FCST YET. WINDS WILL PICK UP FROM THE N
BEHIND THE FRONT...ESPECIALLY WED NIGHT IN COLD AIR ADVECTION /CAA/.

PRECIP WILL BEGIN TO FALL WED NIGHT AS WAA AND DEFORMATION ZONE
PROCESSES DEVELOP. CAA WILL BE COOLING THE COLUMN SO PRECIP COULD
INITIALLY FALL AS RAIN AND THEN CHANGE OVER TO SNOW. KEPT THE FAR SE
FRINGE OF THE FCST AREA ALL RAIN. HOWEVER...THESE ARE DETAILS THAT
WILL NEED TO BE REFINED AS WE GET CLOSER.

THU: PLAYED IT ALL SNOW...WITH A CHANCE OF RAIN TO COVER THE
POSSIBLE MORNING TRANSITION PERIOD S AND E OF THE TRI-CITIES. SNOW
WILL END THU NIGHT.

SOME CHANGES MAY BE REQUIRED TO START/END TIMES AND CHANGEOVER
TIMES...IN FUTURE FCSTS.

00Z EC ENSEMBLE PROBABILITIES FOR 1" OF SNOW ARE 50%. 20% FOR 3" AND
AROUND 10% FOR 6". THE LAST 2 RUNS OF THE DETERMINISTIC EC/GEM/GFS
ARE IN UNISON ON AT LEAST AN ADVISORY LEVEL SNOW EVENT /3-5"/ AND
THERE IS POTENTIAL FOR 6" OR MORE. CONTINUE TO MONITOR FUTURE FCSTS
AND SNOWFALL OUTLOOKS FROM THE WX PREDICTION CENTER.

BELIEVE WE ARE NOT COLD ENOUGH FOR HIGH TEMPS THU. I LOWERED HIGHS
WITH THIS FCST PACKAGE TO AROUND 40F...BUT THERE IS A VERY HIGH
PROBABILITY THAT PART OR MOST OF THE FCST AREA WILL SEE HIGHS IN THE
30S. THIS IDEA HAS MULTIPLE MODELS AND MULTIPLE MODEL CYCLES BEHIND
IT.

FRI: USE OUR HIGH TEMPS WITH CAUTION. IF SNOW DOES ACCUMULATE THU
THEN THE CURRENT TEMPS MAY BUST TOO WARM BY SEVERAL DEGREES.

SAT-SUN: INCREASING CLOUDS AND WARMER. WATCHING POTENTIAL FOR SOME
LIGHT PRECIP.

&&

.AVIATION...(FOR THE 12Z KGRI TAF THROUGH 12Z TUESDAY MORNING)
ISSUED AT 543 AM CDT MON APR 14 2014

SNOW HAS EXITED THE AREA...BUT NORTH WINDS WILL REMAIN QUITE
STOUT TODAY...BUT THE SURFACE PRESSURE GRADIENT SHOULD RELAX
ENOUGH BY EARLY EVENING MONDAY TO ALLOW WIND SPEEDS TO FINALLY
DIMINISH WITH THE SURFACE HIGH SETTLING IN. VFR CONDITIONS ARE
EXPECTED...BUT THERE IS A SMALL CHANCE OF SOME SPRINKLES OR
FLURRIES IN THE LATE AFTERNOON AND EARLY EVENING. THE CHANCE IS
LOW ENOUGH THAT THIS HAS NOT BEEN INCLUDED IN THE CURRENT
FORECAST.

&&

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

$$

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



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