Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 011149
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
649 AM CDT WED OCT 1 2014

.UPDATE...
ISSUED AT 620 AM CDT WED OCT 1 2014

INTERESTING MESO-BETA SCALE CHANGES ARE MODIFYING THE CONDITIONS
AND NECESSITATING SHORT-TERM CHANGES TO THE FCST. A SERIES OF
GRAVITY WAVES HAVE EMANATED FROM THE SHWR ACTIVITY THAT DEVELOPED
OVER CUSTER COUNTY. THIS HAS INITIATED AN ARC OF CLEARING OF THE
STRATUS FROM NW-SE. THE SKY FCST WILL NEED TO BE ADJUSTED. WINDS
HAVE SHIFTED TO THE NW BEHIND THESE WAVES...BUT ARE STILL LIGHT
ENOUGH WITH LOW DWPT DEPRESSIONS THAT THIS CLEARING COULD ALLOW
FOG TO REDEVELOP.

SO EXPECT A TEMPORARY IMPROVEMENT OF SKY/VSBY...BUT VSBYS COULD
LOWER AGAIN IN FOG.

AN SPS WAS POSTED AT 520 AM FOR PATCHES OF DENSE FOG. IT EXPIRES
AT 630. WE WILL CONT TO MONITOR TRENDS FOR ANOTHER ISSUANCE. AT
THIS TIME...THE ONLY DENSE FOG WAS OVER PORTIONS OF N-CNTRL KS.
UPDATED FCST WILL BE OUT SHORTLY.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 408 AM CDT WED OCT 1 2014

ALOFT: A SHORTWAVE TROF WAS MOVING THRU EARLY THIS MORNING AND
HAS BEEN RESPONSIBLE FOR EXTENSIVE MID-HIGH CLOUDS AND EVEN TSTMS
OVER FILLMORE/THAYER COUNTIES. ANOTHER MORE POTENT/AMPLIFIED TROF
WAS OVER THE INTERMOUNTAIN W. THIS TROF WILL CONT E AND WILL BE
MOVING ONTO THE PLAINS AT SUNRISE TOMORROW WITH ITS WAVELENGTH
SHORTENING.

SURFACE: A STATIONARY FRONT BISECTED CNTRL NEB/KS. THIS FRONT
WILL SHOW A GENERAL TENDENCY TO DRIFT E TODAY AND THEN ACCELERATE
S AND E OF THE FCST AREA TONIGHT. LEE CYCLOGENESIS WILL OCCUR NEAR
PUB TODAY AND WILL LATCH ONTO THE FRONT TONIGHT. THIS LOW WILL BE
A PLAYER IN OUR WX THU-FRI.

EARLY THIS MORNING: CLOUDY MOST AREAS WITH HIGHLY VARIABLE
VISIBILITIES IN PATCHY FOG. THERE WILL BE POCKETS OF 1/4SM
VISIBILITY AT TIMES. THE ONLY AREA THAT HAS HAD SUSTAINED 1/4SM IN
DENSE FOG IS LXN. IF THIS CONTS WE WILL ISSUE A SPECIAL WX
STATEMENT /SPS/ BEFORE THE MORNING COMMUTE ENSUES.

SOME SHWRS HAVE DEVELOPED FROM THE SANDHILLS DOWN TO CUSTER
COUNTY. THESE SHWRS WERE ASSOCIATED WITH THE TAIL PORTION OF THE
COMMA CLOUD OVER CNTRL NEB AND COULD SKIRT THRU AREAS ALONG AND N
OF I-80 THRU 9 AM.

TODAY: WHATEVER FOG/STRATUS IS OCCURRING THIS MORNING SHOULD BEGIN
ERODING 9-10 AM AND BE GONE BY 1 PM. HOWEVER...THIS IS BASED JUST ON
PAST EXPERIENCE. THE MODELS DO NOT HANDLE STRATUS WELL. THE EDGES
OF THE STRATUS ARE NEARBY...SO DAYTIME HEATING AND BL MIXING
SHOULD ALLOW FOR EROSION AND EVENTUAL DISSIPATION. FOR WHAT IT`S
WORTH...THE 00Z NAM LOW CLOUD FCST INDICATES IMPROVEMENT...BUT THE
LAST AREAS TO IMPROVE WILL BE ALONG THE NEB HWY 81 CORRIDOR. THE
06Z HRRR IS ON BOARD WITH IMPROVEMENT FROM THE W. IT COULD
POTENTIALLY TAKE UNTIL MID-AFTERNOON TO CLEAR OUT THERE.

AS FOR AFTERNOON TSTM POTENTIAL. IT LOOKS DOUBTFUL IN THIS FCSTRS
ESTIMATION. WHILE THE FRONT WILL REMAIN IN PLACE...THE FCST AREA
WILL BE IN BETWEEN SHORTWAVE TROFS DURING PEAK HEATING AND WEAK
LOW-LVL WINDS MEANS A LACK OF BL CONVERGENCE. FURTHERMORE...THERE
IS A LOT OF DRY AIR ABOVE THE BOUNDARY LAYER AND CONSENSUS OF MOS
AND MODEL 2M TEMPS IS THAT DWPTS WILL MIX DOWN INTO THE 40S W OF
HWY 281 AND 50S TO THE E. THE EASTWARD DRIFT OF THE FRONT WILL
ALSO SHOVE HIGHER DWPTS E OF THE FCST AREA. THAT WILL CREATE CINH
WHICH SHOULD PUT A CAP ON POTENTIAL FOR DEEP CONVECTION...
ESPECIALLY WITHOUT SOME HELP ALOFT. COORDINATED WITH SPC AND
PENDING EVALUATION OF MORNING SOUNDINGS...THEY MAY SCALE BACK THE
SLGT RISK AREA. VERY LOW POTENTIAL IS THERE FOR AN ISOLATED TSTM
...BUT COVERAGE JUST LOOKS WAY TOO LIMITED TO WARRANT A SLGT.

WHILE THE 15Z AND 21Z SREF INDICATED SOME POTENTIAL FOR ISOLATED
TSTMS...THE 03Z CAME IN DRY IN THE 21Z-00Z TIME FRAME.

IF SOMETHING CAN FORM...SREF MLCAPE OF 1000-1500 J/KG IS FCST.
LOW-LVL WINDS WILL BE WEAK...BUT STRONGER WINDS ALOFT WILL RESULT
IN DEEP LAYER SHEAR AROUND 35 KTS. WILL CONT MENTION IN THE HWO
BUT KNOW THAT THIS IS CONDITIONAL BASED IN "IF" A TSTM OR TWO
FORMS AT ALL.

HIGH TEMPS ARE BELOW AVERAGE CONFIDENCE BASED ON STRATUS AND HOW
LONG IT LINGERS. AREAS ALONG HWY 81 YESTERDAY STAYED IN THE 60S
FOR HIGHS BECAUSE CLOUDS LINGERED LONGER THAN ANTICIPATED.

SO BOTTOM LINE FOR TODAY...CLOUDY TO START WITH EVENTUAL CLEARING.
SHOULD BE A NICE AFTERNOON WITH LIGHT WINDS AND LOW HUMIDITY.

TONIGHT: BECOMING CLOUDY. THE NEXT SHORTWAVE TROF WILL
SUPERIMPOSE SUBSTANTIAL QG FORCING/LIFT OVERTOP THE FRONTAL
SURFACE... RESULTING IN DEEP LIFT. THIS WILL RESULT IN A BURST OF
SHWRS AND TSTMS...ALTHOUGH WANING INSTABILITY WILL GRADUALLY BRING
THE THREAT OF THUNDER TO AN END FROM NW-SE. FRONTOGENETIC BANDING
POTENTIAL SUGGESTS THIS COULD RESULT IN A SWATH OF HEALTHY
RAINFALL (0.75" TO 1") FOR SOME PORTIONS OF THE FCST AREA.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 408 AM CDT WED OCT 1 2014

A COUPLE OF UPPER TROUGHS/COLD FRONTS WILL BRING AN END TO THE
MILD WEATHER THE PAST COUPLE OF WEEKS. STARTING ON THURSDAY...AN
UPPER TROUGH WILL BE MOVING ACROSS THE CENTRAL PLAINS AND FAIRLY
WIDESPREAD PRECIPITATION WHICH DEVELOPS WED NIGHT WILL BE ONGOING
THURSDAY MORNING. INSTABILITY REMAINS ACROSS OUR EASTERN ZONES AND
CANNOT RULE OUT AN OCCASIONAL LIGHTNING STRIKE BEFORE PCPN ENDS
W/E BEHIND THE DEPARTING TROUGH AXIS. THE COLD FRONTAL BOUNDARY
WILL CONTINUE TO ADVANCE EAST DURING THE DAY...REACHING IA/EASTERN
KS IN THE AFTN. H85 TEMPS DROP NEARLY 10C FROM WED TO THURS BEHIND
THE FRONT AND HIGH TEMPS ARE EXPECTED TO AVERAGE IN THE LOW/MID
60S.

AS THIS LOW PRESSURE SYSTEM DEPARTS THURSDAY...THE NEXT ONE WILL
BE ON ITS HEELS...DIVING SOUTH FM SASKATCHEWAN ACROSS THE DAKOTAS
AND INTO THE UPPER MIDWEST REGION THURSDAY NIGHT. A REINFORCING
COLD FRONT REACHES OUR NW CWA AROUND MIDNIGHT AND RAPIDLY SWEEPS
SOUTHEAST OVERNIGHT. THREE HOUR PRESSURE RISES BEHIND THE FRONT
AVERAGE 3 TO 6 MB AND THE NOCTURNAL FROPA WILL BE NOTICEABLE WITH
AN INCREASE IN WIND SPEEDS AND GUSTS OVER 30/40 MPH WILL BE
POSSIBLE. STRONG MID LEVEL FRONTOGENESIS ACROSS N/NW NEBRASKA MAY
GENERATE LIGHT PCPN IN VCNTY OF OUR NORTHERN ZONES...BUT WITH LLVL
MOISTURE LACKING HAVE LEFT FORECAST DRY WITH SILENT POPS BUT WILL
NEED TO MONITOR FOR PERHAPS A SPRINKLE MENTION.

FRIDAY IS SHAPING UP TO A COOL WINDY DAY AS THE UPPER SYSTEM
MOVES INTO IOWA. THE SFC GRADIENT REMAINS TIGHT THRU THE DAY IN
BETWEEN THE DEPARTING LOW/COLD FRONT TO THE EAST AND A 1025MB HIGH
PRESSURE SYSTEM BUILDING SOUTHEAST ALONG THE HIGH PLAINS. FORECAST
SOUNDINGS INDICATE MIXING ABOVE H85 WITH WINDS AT THE TOP OF THE
AVERAGING 40KTS AND IF MODEL TRENDS CONTINUE WILL LIKELY NEED A
WIND ADVISORY FRIDAY. IN CAA...DAYTIME TEMPS WILL ONLY AVERAGE IN
THE 50S/LOW 60S.

BIGGER CHANGES IN THE FORECAST COME IN THE FRIDAY NIGHT PERIOD IN
THE COLD AIRMASS...AND WE COULD SEE THE FIRST FREEZE OF THE SEASON
IN SEVERAL LOCATIONS. THE SFC GRADIENT RELAXES FRIDAY NIGHT AS THE
LOW DEPARTS AND THE SURFACE HIGH SETTLES IN. WIND SPEEDS DECREASE
AND GOOD RADIATIONAL CONDITIONS DEVELOP THRU THE OVERNIGHT HOURS.
SFC DPS ARE PROGGED IN THE 20S AND TEMPS SHOULD EASILY DROP INTO
THE 30S FOR LOWS. HAVE WENT WITH TEMPS AROUND THE FREEZING MARK
ACROSS OUR W/NW CWA...WITH MID 30S FARTHER SOUTH...AND THIS IS
BASED ON A BLEND AND THERE IS MODEL SUPPORT FOR TEMPS A SEVERAL
DEGREES COLDER THAN THIS FORECAST. WILL INCLUDE THE COLD TEMPS IN
THE HWO IF TRENDS CONTINUE MAY NEED A FREEZE/FROST HEADLINE AS
THINGS GET CLOSER.

AFTER A COLD START TO THE WEEKEND SATURDAY MORNING...TEMPS WILL
TREND UP OVER THE WEEKEND AND INTO EARLY NEXT WEEK IN HEIGHT RISES
BEHIND THE DEPARTING UPPER TROUGH. AS THE UPPER LOW LIFTS INTO
ONTARIO AND ENERGY ROTATES AROUND THE BACK SIDE...WE COULD SEE
SOME COOLER AIR BACKING IN FROM THE EAST LATE SUNDAY INTO MONDAY
BUT THE AIRMASS CHANGE WILL BE NEGLIGIBLE. CONDITIONS ARE STILL
PREDOMINANTLY DRY SUNDAY THRU TUES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 648 AM CDT WED OCT 1 2014

THIS MORNING: SATELLITE IMAGERY SHOWED SKIES HAVE CLEARED AT EAR
AND WILL BE SHORTLY AT GRI. WHILE THIS HAS RESULTED IN TEMPORARY
IMPROVEMENT...LIGHT WINDS AND LOW DEWPOINT DEPRESSIONS SUGGEST
CONDITIONS WILL REMAIN FAVORABLE FOR FOG TO REDEVELOP. SEE THE
LAST FEW OBS AT LXN. CONDS SHOULD DECAY THRU 13Z BUT RAPIDLY
IMPROVE TO VFR BY 14Z GIVEN THE THIN/PATCHY NATURE OF THE FOG.
CONFIDENCE: HIGH

AFTER 15Z: VFR. LIGHT NW WINDS UNDER 10 KTS. CONFIDENCE: HIGH

TONIGHT: VFR WITH CIRROSTRATUS CIGS INVADING AS SHWRS/TSTMS
DEVELOP UPSTREAM. WINDS WILL SHIFT TO THE N BY 00Z AND REMAIN
UNDER 10 KTS. AFTER 06Z...MULTI-LAYERED CEILINGS WILL GRADUALLY
DESCEND WITH RAIN MOVING IN AFTER 09Z. AT THIS TIME...CIGS/VSBYS
ARE HIGHLY UNCERTAIN AND PREFERRED TO LEAVE VFR FOR NOW AND LET
MODEL GUIDANCE GET A BETTER HANDLE ON HOW THIS COULD EVOLVE. N
WINDS WILL INCREASE TO 10-15 KTS AFTER 06Z.

CONFIDENCE: HIGH THRU 06Z. LOW AFTER 06Z.

&&

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

$$

UPDATE...HALBLAUB
SHORT TERM...HALBLAUB
LONG TERM...FAY
AVIATION...HALBLAUB



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