Area Forecast Discussion
Issued by NWS Hastings, NE

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000
FXUS63 KGID 181100
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
500 AM CST THU DEC 18 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 500 AM CST THU DEC 18 2014

WITH THE ONGOING...REASONABLY "MINOR" SNOW EVENT SEEMINGLY
WINDING DOWN FROM WEST-TO-EAST OVER THESE NEXT FEW HOURS...THERE
IS PROBABLY NOT A WHOLE LOT IN THE WAY OF "HIGH-IMPACT" WEATHER TO
WORRY ABOUT OVER THESE NEXT 24 HOURS. THAT BEING SAID...THE ONE
GLARING CAVEAT INVOLVES A SLIGHT CHANCE OF LIGHT FREEZING DRIZZLE
BOTH IN THE WAKE OF THE SNOW THIS MORNING...AND POSSIBLY AGAIN
OVERNIGHT TONIGHT. THAT BEING SAID...CONFIDENCE IS QUITE LOW IN
ITS OCCURRENCE ESPECIALLY FOR TONIGHT...AND AT THIS TIME NO
IMPACTFUL GLAZE ICING IS EXPECTED TO OCCUR. OTHERWISE...BESIDES
PRECIPITATION CHANCES THE MAIN SHORT TERM ISSUE INVOLVES SKY
COVER/TEMPS...AND UNFORTUNATELY FOR THOSE PARTS OF THE AREA THAT
HAVE LARGELY GONE 7-8 DAYS NOW WITHOUT SEEING SUNSHINE...TODAY
PROBABLY DOESN/T OFFER MUCH HOPE IT APPEARS.

AS OF THIS WRITING AROUND 1030Z/430AM...DARE WE SAY THAT THIS SNOW
EVENT HAS SEEMINGLY WORKED OUT PRETTY DARN WELL VERSUS FORECASTED
EXPECTATIONS (AT LEAST COMPARED TO SOME EVENTS). ALTHOUGH OFFICIAL
OBSERVER TOTALS WILL NOT ARRIVE UNTIL AT LEAST 7-8 AM...LIMITED
GROUND TRUTH FROM AREA LAW ENFORCEMENT THIS MORNING INDICATES
THAT THE 3 WINTER WEATHER ADVISORY COUNTIES
(OSBORNE/JEWELL/MITCHELL) LIKELY AVERAGED AT LEAST 1-2 INCHES OF
ACCUMULATION WITH SOME LOCALLY HIGHER TOTALS POSSIBLE. MEANWHILE
AROUND THE WESTERN/NORTHERN FRINGES OF THIS AREA...TOTALS
GENERALLY AROUND 1 INCH SEEM TO BE THE NORM IN THE FAR
SOUTHEASTERN NEB CWA COUNTIES SUCH AS
NUCKOLLS/THAYER/FILLMORE...ALTHOUGH SUPPOSE A 2-INCH REPORT CANNOT
BE RULED OUT HERE EITHER. FARTHER NORTHWEST...THE TRI-CITIES AREA
(INCLUDING HERE AT THE WFO) HAS RECEIVED WELL UNDER ONE-HALF INCH
FOR THE MOST PART...WITH LIKELY NOTHING MORE THAN A GLORIFIED
DUSTING EXTENDING FARTHER NORTH AND WEST WITHIN THE CWA.
AGAIN...PRETTY DARN CLOSE TO FORECAST EXPECTATIONS YESTERDAY...AS
THE HIGHER SNOW TOTALS HAVE FOCUSED WITHIN CENTRAL/NORTHEAST KS.
AS OF YET...WE ARE NOT AWARE OF ANY ONGOING LIGHT FREEZING DRIZZLE
WITHIN THE CWA...BUT THE LOWEST CEILINGS THAT MIGHT SUPPORT THIS
ARE LARGELY JUST WEST OF THE CWA AT THIS TIME. IN THE MID-UPPER
LEVELS...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA CLEARLY
DEPICT THE PRIMARY SHORTWAVE TROUGH OF INTEREST LIFTING ACROSS
NORTHEAST KS/SOUTHEAST NEB TOWARD NORTHERN MO/SOUTHERN IA...WHILE
UPSTREAM A LARGER SCALE TROUGH PERSISTS OVER THE WESTERN CONUS
WITH ADDITIONAL SHORTWAVE ENERGY. AT THE SURFACE...A WEAK GRADIENT
BETWEEN BROAD HIGH PRESSURE TO THE NORTHEAST AND LOW PRESSURE TO
THE SOUTHWEST IS PROMOTING LIGHT EAST-SOUTHEASTERLY BREEZES ONLY
AROUND 5 MPH OR LESS...WHICH HAS CERTAINLY HELPED LESSEN THE
IMPACT OF THIS SNOW EVENT AS WELL. TEMP-WISE...WIDESPREAD CLOUDS
ARE AGAIN HOLDING THINGS WELL-ABOVE MAX COOLING POTENTIAL...WITH
MOST OF THE CWA LIKELY DROPPING NO LOWER THAN THE LOW 20S THIS
MORNING.

FORECAST WISE AND STARTING WITH EARLY THIS MORNING THROUGH
SUNSET...THE MILLION DOLLAR QUESTION IS WHETHER OR NOT AT LEAST
PATCHY/LIGHT FREEZING DRIZZLE SHOWS ITS HAND YET THIS MORNING IN
THE WAKE OF THE EASTWARD-DEPARTING SNOW. SPEAKING OF THE SNOW...BY
6-7 AM EXPECT THE VAST MAJORITY OF THE CWA TO BE SNOW FREE...WITH
MAYBE ONLY AN ADDITIONAL FEW TENTHS OF AN INCH ACCUMULATION
POSSIBLE ALONG THE HIGHWAY 81 CORRIDOR IN THE FAR EAST BEFORE
ENDING COMPLETELY BY MID-MORNING. IN THE MID-UPPER
LEVELS...ISENTROPIC DOWNGLIDE COMMENCES AND A LOW-AMPLITUDE
SHORTWAVE RIDGE MOVES IN BEHIND THE DEPARTING SYSTEM...ALL BUT
ASSURING THE END OF MEASURABLE WINTRY PRECIP FOR THE DAY.
HOWEVER...AS HAS BEEN PONDERED FOR A FEW DAYS NOW...AS DENDRITIC
LAYER/MID LEVELS DRY OUT BEHIND THE DEPARTING SYSTEM...THERE COULD
BE JUST ENOUGH LIFT REMAINING IN THE LINGERING LOWER STRATUS DECK
TO PROMOTE A LITTLE LIGHT DRIZZLE...POTENTIALLY THROUGH AROUND
MID-DAY. ALTHOUGH CONFIDENCE IS LOW IN THIS PROSPECT...FELT IT
WOULD BE WISE TO KEEP A PATCHY -FZDZ MENTION GOING GIVEN THAT IT
WAS ALREADY IN THE FORECAST...AND THAT WFO LBF JUST WEST OF THE
CWA HAS REPORTED A LITTLE OF IT FALLING AT THEIR OFFICE DURING THE
NIGHT. BY THIS AFTERNOON...FEEL FAIRLY SAFE IN KEEPING THIS
POSSIBILITY OUT OF THE FORECAST...AS DESPITE THE LIKELY-LINGERING
STRATUS DECK THERE SHOULD NO LONGER BE ENOUGH LIFT TO SUPPORT
DRIZZLE. SPEAKING OF SKY COVER...ALTHOUGH MODELS INDICATE
"CLEARING" A FEW THOUSAND FEET UP AT THE 850 MILLIBAR LEVEL...IT
APPEARS THAT LOWER STRATUS BASED AROUND 900/925MB WILL PROBABLY
TRY HOLDING PRETTY FIRM OVER AT LEAST THE MAJORITY OF THE
CWA...AND THUS HAVE UNFORTUNATELY MAINTAINED A NO-BETTER THAN
MOSTLY CLOUDY SKY COVER THROUGH THE DAY...ALTHOUGH SUPPOSE A FEW
PLACES ESPECIALLY NEAR THE WESTERN EDGES OF THE CWA COULD MAYBE
SEE A FEW PEEKS OF SUN...BUT WOULD NOT BET MUCH ON IT. TEMP-
WISE...FELT IT PROB WOULD BE BEST TO AIM PLACES ONLY VERY SLIGHTLY
"WARMER" THAN YESTERDAY...AND THUS CALLING FOR MOST PLACES TO
REACH UPPER 20S/LOW 30S AT BEST.

FOR THIS EVENING/TONIGHT...THERE IS CERTAINLY A CHANCE THAT THINGS
COULD REMAIN QUIET/VERY UNEVENTFUL ACROSS THE VAST MAJORITY OF
THE CWA...AND AM CERTAINLY NOT EXPECTING ANY MEASURABLE PRECIP
POTENTIAL. BUT THAT BEING SAID...THERE ARE AT LEAST WEAK SIGNALS
THAT SOME LIGHT FREEZING DRIZZLE AND/OR AT LEAST PATCHY FOG COULD
TRANSPIRE IN SOME PLACES. ALTHOUGH CONFIDENCE IN OCCURRENCE IS
LOW...LET ALONE AREAL PLACEMENT...IT WOULD SEEM THAT GENERALLY
SPEAKING THE GREATER FOG POTENTIAL MIGHT TARGET WESTERN
ZONES...WHILE THE SLIGHT CHANCE OF FREEZING DRIZZLE COULD MAINLY
TARGET EASTERN ZONES. FOR NOW THOUGH...HAVE KEPT A MORE BROAD
MENTION ACROSS THE AREA LARGELY IN LINE WITH WHAT WAS ALREADY IN
PREVIOUS FORECAST...WHILE ADDING THE FOG MENTION WEST. AS FOR THE
MID-UPPER LEVEL PICTURE...FORCING IS NOT STRONG BUT THERE COULD
BE A LITTLE LIFT FROM THE APPROACH OF THE NEXT LOW AMPLITUDE
SHORTWAVE TROUGH ENTERING WESTERN PORTIONS OF NEB/KS POST-
MIDNIGHT. ASSUMING THAT A LOW STRATUS LAYER REMAINS FIRMLY
INTACT...00Z/06Z NAM FORCAST SOUNDINGS AND PLAN-VIEW RELATIVE
HUMIDITY PROGS SUGGEST MOISTURE DEPTH COULD BE JUST ENOUGH TO
GENERATE SOME LIKELY LOW-IMPACT SPOTTY FREEZING DRIZZLE...BUT IT
SURE LOOKS IFFY. PONDERED PULLING OUT THIS SLIGHT CHANCE MENTION
ALTOGETHER...BUT AGAIN WITH IT ALREADY BEING IN THE FORECAST FELT
THERE WAS JUST ENOUGH SUPPORT TO LEAVE IT THERE FOR NOW AND GIVE
DAY SHIFT ANOTHER LOOK AT LATEST MODEL RUNS. AT ANY RATE...NOT
EXPECTING ANY KIND OF IMPACTFUL ICING EVENT. AS FOR SURFACE
FEATURES TONIGHT...BREEZES WILL GENERALLY REMAIN WELL UNDER 10 MPH
FROM MAINLY A SOUTHERN DIRECTION. TEMP-WISE...AGAIN ASSUMING
PLENTIFUL CLOUD COVER REMAINS...KEPT LOWS SOLIDLY 3-5 DEGREES
ABOVE TOO-COLD-LOOKING 00Z MET/MAV GUIDANCE...BUT DID NUDGE DOWN
PREVIOUS FORECAST SLIGHTLY...AIMING MOST OF THE CWA BETWEEN 21-25
DEGREES.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 348 AM CST THU DEC 18 2014

GUIDANCE SUGGESTS SEVERAL UPPER TROPOSPHERIC SHORT WAVES WILL BE
NOTED MOVING OVER THE CENTRAL PLAINS DURING THE LONG TERM FORECAST
PERIOD. THE FIRST SHORT WAVE IS EXPECTED TO EXIST OVER THE CENTRAL
HIGH PLAINS TO START THE LONG TERM FORECAST PERIOD AT 12Z
FRIDAY...WITH THIS SHORT WAVE THEN EXPECTED TO CLEAR THE CENTRAL
PLAINS DURING THE DAY FRIDAY. A SECOND UPPER TROPOSPHERIC SHORT
WAVE IS EXPECTED TO CLEAR OUR AREA SATURDAY INTO SATURDAY
NIGHT...WITH ONE MORE SHORT WAVE THEN EXPECTED SUNDAY NIGHT INTO
MONDAY.

STARTING WITH FRIDAY MORNING...GUIDANCE FROM THE NAM AND
OPERATIONAL GFS SUGGEST 0-0.5KM RELATIVE HUMIDITY VALUES IN EXCESS
OF 90%...ALONG WITH 0-0.5KM BULK SHEAR NEAR OF JUST ABOVE
10KTS...AS WELL AS SOME SUBTLE LIFT AHEAD OF THE FIRST OF THE
AFOREMENTIONED UPPER TROPOSPHERIC SHORT WAVES...MAY PROMOTE
PERIODIC LIGHT FREEZING DRIZZLE ACROSS EASTERN PORTIONS OF THE CWA
THROUGH LATE MORNING. IT IS WORTH MENTIONING THAT FORECAST
PROXIMITY SOUNDINGS FROM ACROSS OUR CWA...PER THE NAM AND
OPERATIONAL GFS...SUGGEST THE LAYER OF SATURATION NEAR THE SURFACE
WILL BE VERY THIN AND BASED ON THIS DATA...IT SHOULDN/T TAKE LONG
TO MIX OUT THE SATURATED LAYER POST- SUNRISE. BUT NONETHELESS
THERE IS STILL AN OPPORTUNITY FOR FREEZING DRIZZLE FOR AT LEAST A
TIME FRIDAY MORNING AND GIVEN THIS...WILL GO AHEAD AND CONTINUE
SUCH WORDING IN THE FORECAST THROUGH 15Z FRIDAY.

OF THE THREE AFOREMENTIONED SHORT WAVES...THE OPERATIONAL GFS AND
EC BOTH SUGGEST THE THIRD WAVE...SUNDAY NIGHT INTO MONDAY...WILL
BE THE STRONGEST AS IT CLEARS THE REGION. IN FACT...DPVA AND UPPER
TROPOSPHERIC THERMAL ADVECTION...AS WELL AS TROPOSPHERIC
MOISTURE...IN ASSOCIATION WITH THE FIRST TWO WAVES APPEAR SO
MEAGER THAT THE PROBABILITY OF MEASURABLE PRECIPITATION PRODUCTION
WITH EITHER OF THE TWO FIRST WAVES SEEMS VERY LOW AND AS A
RESULT...WENT AHEAD WITH A PRECIPITATION-FREE FORECAST FRIDAY
THROUGH THE DAY SUNDAY.

HEADING INTO SUNDAY NIGHT...GUIDANCE SUGGESTS BOTH DPVA AND UPPER
TROPOSPHERIC THERMAL ADVECTION WILL INCREASE ENOUGH FOR
PRECIPITATION PRODUCTION ACROSS PORTIONS OF THE
REGION...ESPECIALLY ACROSS NORTHERN AND EASTERN NEBRASKA AS THE
THIRD SHORT WAVE APPROACHES. GIVEN THIS...WENT AHEAD WITH ~20%
POPS ACROSS EXTREME EAST/NORTHEASTERN PORTIONS OF THE CWA SUNDAY
NIGHT INTO MONDAY. ALTHOUGH IT APPEARS THE UPPER TROPOSPHERIC
SHORT WAVE WILL CLEAR THE REGION DURING THE DAY MONDAY...THERE ARE
ALSO INDICATIONS...FROM THE OPERATIONAL GFS AND EC...THAT THE
LEFT-FRONT QUADRANT OF A ~150KT UPPER TROPOSPHERIC JET STREAK WILL
DEVELOP OVER THE CENTRAL PLAINS MONDAY NIGHT INTO TUESDAY...THUS
PROVIDING ADDITIONAL CHANCES FOR PRECIPITATION PRODUCTION. GIVEN
THIS...WENT AHEAD WITH ~20% POPS ACROSS NORTHERN AND EASTERN
PORTIONS OF OUR CWA MONDAY NIGHT INTO TUESDAY AS WELL.

FORECAST PROXIMITY SOUNDINGS FROM ACROSS THE OUR NORTHERN AND
EASTERN CWA...PER THE OPERATIONAL GFS AND EC...SUGGEST
PRECIPITATION TYPE WILL VARY BETWEEN LIGHT RAIN AND LIGHT SNOW
MONDAY THROUGH TUESDAY. IT IS WORTH MENTIONING THAT PRECIPITATION
TYPE WILL NEED TO BE CLOSELY MONITORED EARLY MONDAY MORNING JUST
PRIOR TO SUNRISE AS THIS IS A TIME WHEN FORECAST PROXIMITY
SOUNDINGS FROM THE OPERATIONAL GFS AND EC BOTH SUGGEST A STRONG
ELEVATED WARM LAYER WILL CONTINUE TO PROMOTE LIQUID PRECIPITATION
AS SURFACE TEMPERATURE READINGS APPROACH THE FREEZING MARK. AT
THIS TIME THE CURRENT FORECAST CALLS FOR SURFACE TEMPERATURE
READINGS TO REMAIN JUST ABOVE FREEZING THROUGH SUNRISE MONDAY BUT
AGAIN...THIS WILL NEED TO BE MONITORED AS ANY DECREASE IN THE LOWS
FOR MONDAY MORNING COULD PRESENT THE POSSIBILITY FOR PERIODIC
LIGHT FREEZING RAIN ACROSS OUR NORTHEAST FOR A FEW HOURS MONDAY
MORNING.

A PERSISTENT SOUTHERLY COMPONENT TO THE BOUNDARY-LAYER WIND FIELD
AND RESULTANT THERMAL ADVECTION SHOULD PROMOTE A GENERAL WARMING
TREND FRIDAY THROUGH MONDAY. AFTERNOON HIGHS IN THE 30S AND LOW
40S ON FRIDAY ARE CURRENTLY EXPECTED TO RISE INTO THE 40S AND LOW
50S ACROSS THE CWA BY MONDAY...WHILE OVERNIGHT LOWS START IN THE
TEENS AND LOW 20S FRIDAY NIGHT BUT SHOULD EVENTUALLY CLIMB INTO
THE UPPER 20S AND LOWER 30S BY SUNDAY NIGHT. THE PASSAGE OF A
BOUNDARY-LAYER BAROCLINIC ZONE MONDAY...IN ASSOCIATION WITH THE
UPPER TROPOSPHERIC SHORT WAVE ALSO CLEARING THE AREA...SHOULD THEN
ALLOW FOR A SOMEWHAT COOLER FINISH TO THE FORECAST PERIOD...WITH
HIGHS IN THE MID 30S TO LOW 40S AND LOWS IN THE BACK INTO THE 20S
BY NEXT WEDNESDAY.

&&

.AVIATION...(FOR THE 06Z KGRI/KEAR TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1152 PM CST WED DEC 17 2014

YET AGAIN...ANOTHER TAF PERIOD WITH A SOMEWHAT CHALLENGING/TRICKY
FORECAST REGARDING MAINLY CEILING TRENDS...BUT POSSIBLY VISIBILITY
AS WELL. ON TOP OF THIS...AT LEAST A BRIEF PERIOD OF LIGHT SNOW IS
LIKELY RIGHT AWAY DURING THESE FIRST 6 HOURS EARLY THIS
MORNING...WITH AMOUNTS LIKELY AVERAGING LESS THAN ONE-HALF INCH.
ALTHOUGH NOT INDICATED IN THE TAFS DUE TO LACK OF CONFIDENCE IN
COVERAGE/OCCURRENCE...A BRIEF PERIOD OF LIGHT FREEZING DRIZZLE
CANNOT BE RULED AS WELL. SO...THE BOTTOM LINE IS THAT CEILING-
WISE...DESPITE SOME MODELS/GUIDANCE SUGGESTING A RETURN TO
PREVAILING VFR THROUGH MUCH OF THE LATTER HALF OF THE
PERIOD...HAVE INSTEAD MAINTAINED A MORE PESSIMISTIC ROUTE AS
SUGGESTED BY OTHER MODELS/GUIDANCE AND THE PREVIOUS
FORECAST...WITH A COMBINATION OF MVFR/IFR CEILING PERSISTING
THROUGH NEARLY THE ENTIRE PERIOD. VISIBILITY WISE...ALTHOUGH SOME
LIGHT FOG COULD BECOME A FACTOR...FOR NOW HAVE ONLY INDICATED SUB-
VFR CONDITIONS IN ASSOCIATION WITH ANY FALLING SNOW DURING THE
FIRST SEVERAL HOURS. FORTUNATELY...SURFACE WINDS WILL NOT BE A
MAJOR AVIATION ISSUE THROUGH THE PERIOD...WITH SUSTAINED SPEEDS
AVERAGING UNDER 10KT THROUGHOUT...AS DIRECTION TRANSITIONS FROM
EASTERLY TO SOUTHERLY.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...WINTER WEATHER ADVISORY UNTIL 9 AM CST THIS MORNING FOR KSZ007-
     018-019.

&&

$$

SHORT TERM...PFANNKUCH
LONG TERM...BRYANT
AVIATION...PFANNKUCH


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