Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 131903
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
203 PM CDT SUN APR 13 2014

.UPDATE...
ISSUED AT 202 PM CDT SUN APR 13 2014

NEEDLESS TO SAY...WE HAVE UNDERESTIMATED THE WINTRY ASPECT OF THIS
STRONG SPRING LOW PRESSURE SYSTEM. AS COLDER AIR HAS SLAMMED INTO
THE AREA BOTH AT THE SURFACE AND ALOFT...A WELL-DEFINED
DEFORMATION ZONE EVIDENT AT 700 MILLIBARS AND WELL-CAPTURED BY
MODELS SUCH AS THE 17Z RAP13...HAS RESULTED IN A FAIRLY WIDE BAND
OF ACCUMULATING SNOW ACROSS ROUGHLY THE NORTHWEST HALF OF THE
CWA...WITH SOME SLEET ON ITS LEADING EDGE. DUE TO THE INTENSITY OF
THE BAND...SOME ROAD ACCUMULATION HAS TAKEN PLACE AND UNOFFICIAL
ACCUMULATIONS ON GRASSY SURFACES IN WESTERN COUNTIES HAS REACHED
2+ INCHES IN SOME AREAS. OBVIOUSLY WHEN COMBINED WITH THE STRONG
WINDS...VISIBILITIES HAVE BEEN LESS THAN IDEAL AND NEAR-WHITE OUT
CONDITIONS ARE PRESENT IN THE HEAVIEST BANDS AS EVIDENCED BY AREA
WEBCAMS AND AUTOMATED OBS AT AIRPORT SITES SUCH AS ORD/LEXINGTON.
TO ACKNOWLEDGE THE OBVIOUS...A WINTER WEATHER ADVISORY HAS BEEN
ISSUED THROUGH 01Z/8PM FOR ROUGHLY THE WESTERN 1/2 OF THE NEB
CWA...WHERE ACCUMULATIONS ON GRASSY SURFACES ARE MOST LIKELY TO
REACH 2-4 INCHES. OUTSIDE THE ADVISORY AREA...STILL EXPECT AT
LEAST SOME SNOW ACCUMULATION BEFORE THIS SYSTEM PULL OUT
TONIGHT...BUT MAINLY ONLY IN THE 1 TO 1.5 INCH RANGE. WILL HAVE TO
CLOSELY WATCH THE SNOW BAND THOUGH FOR A POSSIBLE EASTWARD
EXPANSION OF THE ADVISORY. PER THE RAP/HRRR...THIS DECENT APRIL
SNOW EVENT SHOULD GRADUALLY EXIT THE EASTERN/SOUTHERN CWA DURING
THE 9PM-MIDNIGHT TIME FRAME. AS FOR THUNDERSTORMS...A FEW HUNDRED
J/KG OF MUCAPE REMAINS IN SOUTHEAST COUNTIES...BUT ANY THREAT FOR
MARGINALLY SEVERE STORMS IS QUICKLY FADING IF IT HASNT ALREADY.


UPDATE ISSUED AT 1100 AM CDT SUN APR 13 2014

ITS ALREADY BEEN A BUSY MORNING...WITH SEVERAL STORMS WITHIN THE
SOUTHEAST 1/2 OF THE CWA PRODUCING COPIOUS AMOUNTS OF SMALL
HAIL...AND A FEW HAIL STONES TO AROUND QUARTER SIZE EARLIER ON.
AS THE DAY GOES ON...THUNDERSTORM COVERAGE IS EXPECTED TO STEADILY
FADE AWAY FROM NORTHWEST-TO-SOUTHEAST...BUT THAT OPENS THE DOOR
FOR AT LEAST LIGHT...SLUSHY SNOW ACCUMULATIONS TO BECOME THE MAIN
STORY FROM NORTHWEST TO SOUTHEAST. THE BIGGEST CHANGE FROM
PREVIOUS FORECAST WAS THAT SNOW ACCUMULATION POTENTIAL...AGAIN
MAINLY ON GRASSY SURFACES...WAS BEEFED UP INTO THE 1-2 INCH RANGE
FOR AREAS GENERALLY WEST OF A ALMA-FULLERTON LINE...WITH 1 INCH OR
LESS EXPECTED FARTHER SOUTH/EAST. ALTHOUGH THESE AMOUNTS ALONE DO
NOT NORMALLY JUSTIFY A WINTER WEATHER ADVISORY...AND ROAD
ACCUMULATION WOULD PROBABLY BE MINIMAL...WILL HAVE TO KEEP AN EYE
ON VISIBILITIES AS THE DAY GOES ON INTO THIS EVENING IN CASE
TRAVEL DOES BECOME HAZARDOUS ENOUGH TO JUSTIFY A BRIEF WINTER
HEADLINE. FOR NOW...WILL JUST CONTINUE TO MENTION LOCALIZED
VISIBILITY RESTRICTION WITHIN THE ONGOING WIND ADVISORY
PRODUCT...WHICH IS WORKING OUT PRETTY WELL BY THE WAY WITH
WIDESPREAD SUSTAINED SPEEDS OF 25-35 MPH. WE HAVE EVEN HAD A FEW
ENHANCED GUSTS INTO THE 50-58 MPH RANGE...LIKELY AIDED BY FALLING
PRECIPITATION...BUT EXPECT THE OCCURRENCE OF ANY WARNING-LEVEL
SPEEDS SHOULD BE LOCALIZED ENOUGH/FLEETING ENOUGH TO PRECLUDE THE
ISSUANCE OF A FORMAL HIGH WIND WARNING. NEEDLESS TO SAY...TEMPS
ARE FALLING STEADILY...AND ALL BUT ROUGHLY THE SOUTHEAST 1/4 OF
THE CWA SHOULD BE SOLIDLY DOWN IN THE 30S BY MID-AFTERNOON. ENDING
ON A POSITIVE NOTE THOUGH...ESPECIALLY THE NORTHWEST TWO-THIRDS
OF THE CWA SHOULD REALIZE AT LEAST 0.50-1.00 INCH OF MUCH-NEEDED
PRECIPITATION FROM THIS EVENT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 457 AM CDT SUN APR 13 2014

MAIN FOCUS WILL BE ON CHANCES OF PRECIPITATION THROUGHOUT THE SHORT
TERM...ALONG WITH DETERMINING PRECIPITATION TYPE AND POSSIBILITY OF
LINGERING SEVERE WEATHER CHANCES THIS MORNING. SNOW AMOUNTS WERE
ALSO CONSIDERED FOR THIS AFTERNOON INTO TONIGHT.

THIS FORECAST BEGINS WITH A SURFACE COLD FRONT JUST TO THE SOUTH OF
THE CWA AND HAS STALLED...AND MAY WOBBLE TEMPORARILY NORTH EARLY
THIS MORNING BEFORE HEADING SOUTH LATER TODAY AS COLD AIR ADVECTION
TAKES FIRM GRIP. THE TEMPERATURES SHOULD PRETTY MUCH FALL ALL DAY
INTO THE NIGHT. THERE IS STILL A SHOT AT SOME THUNDERSTORM ACTIVITY
THIS MORNING WITH MUCAPES UP TO 1000 J/KG. THERE IS ENOUGH BULK
SHEAR COMBINED WITH THIS LINGERING INSTABILITY TO KEEP A CHANCE OF
SOME MARGINALLY SEVERE HAIL IN THE HWO MENTIONED...MAINLY IN OUR
SOUTH. I TOOK OUT THUNDERSTORM CHANCES IN OUR NORTH COMPLETELY AS
THERE IS NO SUPPORT FOR THUNDERSTORM ACTIVITY THERE. LEANED TOWARD
BCCONSRAW FOR HIGHS TODAY AND CONSRAW FOR LOWS TONIGHT. NO
THUNDERSTORMS ARE EXPECTED BY THIS AFTERNOON AS ELEVATED INSTABILITY
GETS WIPED OUT BY COLD AIR AS THE CANADIAN HIGH BUILD SOUTH. THE
CHANCES OF PRECIPITATION INCREASE QUITE A BIT TODAY AS THE
APPROACHING SHORTWAVE TROUGH MAKES ITS WAY INTO THE CENTRAL
PLAINS. THE LONGWAVE TROUGH AXIS FINALLY CROSS THE CWA
TONIGHT...ENDING THE CHANCE OF PRECIPITATION FOR MOST OF THE CWA
BY NEAR SUNRISE MONDAY MORNING. THE BULK OF ANY SUPPORT WITH THE
LONGWAVE TROUGH REMAINS TO THE SOUTH...HELPING TO KEEP OUR
SOUTHERN CWA WITH CHANCES OF PRECIPITATION A BIT LONGER THAN THE
REST OF US.

I EXTENDED THE WIND ADVISORY BOTH EARLIER AND LATER IN TIME AS THE
SURFACE PRESSURE GRADIENT IS TIGHTLY PACKED THIS MORNING.
OBSERVATIONS HAVE ALREADY FLIRTED WITH WIND ADVISORY SO THE ADVISORY
IS VALID ALL MORNING UNTIL 10 PM TONIGHT. THE TRANSITION TO ANY SNOW
IS AN EDUCATED GUESS AND IS DIFFICULT TO DETERMINE GIVEN SUCH A
TIGHT TEMPERATURE GRADIENT AS WELL. ANY SNOW AMOUNTS DO NOT LOOK
LARGE...HOWEVER...I INCREASED AMOUNTS A BIT FROM THE PREVIOUS
FORECAST...ESPECIALLY AS CHANCES OF PRECIPITATION HOLD ON A BIT
LONGER IN THE SOUTH AFTER THE ENTIRE AREA IS BLASTED BY TEMPERATURES
COLD ENOUGH FOR SNOW EVERYWHERE.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 457 AM CDT SUN APR 13 2014

DAILY TEMPERATURES WILL FAVOR COOLER THAN NORMAL THIS WEEK...WITH
MUCH COOLER THAN NORMAL MON AND THEN THU-FRI. ENSEMBLE MULTI-DAY 500
MB MEANS CONTINUE TO ADVERTISE THE MEAN TROF OVER THE CNTRL USA.

ALOFT: AN ANOMALOUS -2 STANDARD DEVIATION TROF WILL CROSS THE CNTRL
PLAINS MON FOLLOWED BY NW FLOW TUE. A SHORTWAVE RIDGE WILL ARRIVE
LATE TUE...AHEAD OF THE NEXT LOW-AMPLITUDE PACIFIC TROF. SOME SPREAD
BEGINS TO DEVELOP WED AS TO WHAT OCCURS WITH THIS TROF. THE PAST 2
RUNS OF THE EC/GFS AND THE 00Z GEM ARE IN GOOD AGREEMENT ON THE TROF
ADVANCING ONTO THE PLAINS WED. HOWEVER...YESTERDAYS 12Z GFS/GEM
ATTEMPT TO CLOSE IT AND CUT IT OFF FROM THE FLOW OVER THE SRN
ROCKIES. MOST GFS ENSEMBLE MEMBERS DO THE SAME.

CHATTED WITH WPC MEDIUM RANGE DESK AROUND 545Z AND ONLY ABOUT 10% OF
THE EC MEMBERS CUT IT OFF. THE GFS AND ITS ENSEMBLE MEMBERS HAVE
BEEN A LITTLE TOO EAGER TO CUT IT OFF. SO WE WILL MAINTAIN A MORE
PROGRESSIVE STANCE...BUT THAT IS DIFFICULT TO TRANSLATE INTO THE
FCST SINCE THE EC ENSEMBLE MEAN KEEPS THE TROF OVER HEAD THU. EXPECT
A RIDGE TO MOVE IN FRI-SAT.

SURFACE: HIGH PRES BUILDS IN MON...CROSSES THE REGION MON NIGHT AND
THE WARM SECTOR DEVELOPS TUE AS A CLIPPER-TYPE LOW SLIDES DOWN THE
LEE TROF. COLD FRONTAL PASSAGE OCCURS WED AS THIS LOW HEADS FOR THE
GREAT LAKES. HIGH PRES ARRIVES THU AND SHIFTS E FRI-SAT. THERE COULD
BE A LOW THAT TRIES TO TRACK UP THE FRONT THU...SE OF THE FCST AREA
BUT THIS COULD BE DUE TO SOME MODELS CUTTING OFF THE TROF.

HAZARDS: FIRE WX COULD BE A PROBLEM TUE AFTERNOON.

FCST CONFIDENCE IS ABOVE AVERAGE MON-TUE...AVERAGE WED AND BELOW
AVERAGE THU-SAT.

THE DAILY DETAILS...

MON: DECREASING MID-HIGH CLOUDS IN THE MORNING ONLY TO HAVE LOW-
LEVEL STRATOCU REDEVELOP IN THE AFTERNOON. UNSEASONABLY CHILLY. 850
MB TEMPS AND THE TROF ALOFT ARE BOTH 2 STANDARD DEVIATIONS BELOW
NORMAL. AND WHILE NO RECORDS WILL BE THREATENED...THIS WILL GO DOWN
AS ONE OF THE TOP 10 COLDEST DAYTIME HIGH TEMPS ON RECORD FOR APRIL
14TH.

CANT COMPLETELY RULE OUT SOME BRIEF/SMALL POCKETS OF AFTERNOON
SPRINKLES/FLURRIES N OF HWY 6 IN S-CNTRL NEB. COLD AIR ALOFT WILL
RESULT IN WIDESPREAD STRATOCU DEVELOPMENT. THE ISSUE IS HOW DEEP?
THE GFS IS 8-10F WARMER WITH ITS HIGH TEMPS VS THE NAM AND THIS
RESULTS IN DEEPER MIXING AND A DRIER SUBCLOUD LAYER. REGARDLESS OF
WHICH MODEL IS CHOSEN...THE CLOUD BEARING LAYER WILL BE WITHIN THE
IDEAL SNOW GROWTH ZONE. IF THE NAM IS RIGHT THEN SPRINKLES/FLURRIES
WILL MAKE IT TO THE SURFACE. FOR NOW THE FCST IS DRY...BUT POPS WERE
INCREASED.

MULTIPLE MODELS ARE GENERATING SOME VERY LIGHT QPF WHICH IS
CERTAINLY OVERDONE...BUT THE HINT IS THERE.

TUE: A COLD START WITH A HARD FREEZE EXPECTED EVERYWHERE. BUT A VERY
NICE IMPROVEMENT AS THE COLD DEPARTS AND WARM AIR ADVECTION /WAA/
DEVELOPS. GUSTY SW WINDS PROPEL TEMPS BACK TO NEAR NORMAL FOR MID
APRIL. WINDS AND LOW RH COULD LEAD TO CRITICAL FIRE DANGER S OF HWY
6. BOTH THE GFS/NAM SUGGEST MIXING HEIGHTS TO 750 MB. THIS SUGGESTS
DEWPOINTS DROPPING INTO THE UPPER TEENS.

WED: COLD FRONTAL PASSAGE /CFP/ AND IT`S NOW LOOKING LIKE THE
BEGINNING OF THE DAY VS 24 HRS AGO WHEN THE CFP WAS MODELED LATE
DAY. BELIEVE IT WILL END UP MOSTLY CLOUDY.

THU: CHILLY CANADIAN HIGH PRES BUILDS IN FROM THE N. HOWEVER...THERE
IS POTENTIAL FOR A LOW TO TRACK UP THE FRONT WED NIGHT INTO THU...
WHICH WILL BE STATIONARY FROM THE TX PANHANDLE TO THE GREAT LAKES.
MINOR DEFORMATION ZONE RAIN/SNOW COULD DEVELOP.

HARD TO KNOW HOW CHILLY TO TAKE HIGH TEMPS THU. THERE APPEARS A
DECENT CHANCE THAT CLOUDS WILL PUT A STRANGLE HOLD ON TEMPS. WE ARE
SEEING GUIDANCE SUGGESTIVE OF HIGHS NO BETTER THAN 35-42F. SUFFICE
TO SAY WE MAY BE GOING COLDER WITH FUTURE FCSTS.

FRI-SAT: GENERAL IMPROVEMENT EXPECTED AND WHILE MODEL DISPARITY
EXISTS...IT DOES APPEAR HIGH PRES WILL REASSERT ITSELF FRI WITH
RETURN FLOW AND WAA DEVELOPING INTO SAT.

&&

.AVIATION...(FOR THE 18Z KGRI TAF THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 202 PM CDT SUN APR 13 2014

THE WINTRY ASPECT OF THIS LOW PRESSURE SYSTEM HAS DEFINITELY
REARED ITS HEAD MORE THAN PREVIOUSLY EXPECTED. AS A RESULT...THE
EXPECTATION IS NOW FOR POTENTIALLY SEVERAL HOURS OF IFR
VISIBILITY/CEILING THIS AFTERNOON INTO EARLY THIS EVENING IN
FALLING SNOW...WHICH COULD AT LEAST BRIEFLY SLIP INTO LIFR
VISIBILITY IN THE HEAVIEST BANDING. THE MAIN PART OF THE SNOW BAND
SHOULD CLEAR THE TERMINAL BY AROUND 00Z...BUT LINGERING LIGHT SNOW
IN MVFR VISIBILITY COULD LINGER UNTIL CLOSER TO 03Z. WHENEVER SNOW
DOES FINALLY END THIS EVENING...THAT SHOULD BE THE END OF
PRECIPITATION FOR THE PERIOD...AND HAVE CEILING RETURNING TO VFR
AROUND THIS TIME AS WELL. NORTH WINDS WILL REMAIN STRONG THROUGH
ESPECIALLY THE FIRST 6-9 HOURS OF THE PERIOD WITH SUSTAINED SPEEDS
25-30KT AND GUSTS UP INTO THE 35-40KT RANGE...BUT SPEEDS WILL
GRADUALLY SUBSIDE OVERNIGHT AND BY SUNRISE MONDAY MORNING NORTH-
NORTHWESTERLY GUST POTENTIAL SHOULD AVERAGE ONLY 20-25KT.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY UNTIL 10 PM CDT THIS EVENING FOR NEZ039>041-
     046>049-060>064-072>077-082>087.

     WINTER WEATHER ADVISORY UNTIL 8 PM CDT THIS EVENING FOR NEZ039-
     040-046-047-060>062-072>074-082>084.

KS...WIND ADVISORY UNTIL 10 PM CDT THIS EVENING FOR KSZ005>007-
     017>019.

&&

$$

UPDATE...PFANNKUCH
SHORT TERM...HEINLEIN
LONG TERM...HALBLAUB
AVIATION...PFANNKUCH



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