Area Forecast Discussion
Issued by NWS Hastings, NE

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000
FXUS63 KGID 151249
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
649 AM CST MON DEC 15 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 612 AM CST MON DEC 15 2014

APOLOGIZE FOR THE LATE DISCUSSION...BUT IN SHORT HAVE BEEN QUITE
BUSY CHASING AN EVER-CHANGING/COMPLEX SITUATION ACROSS THE CWA
OVERNIGHT AS A HIGHLY-VARIABLE PRECIPITATION REGIME IS CURRENTLY
IN PLACE HIGHLIGHTED BY A GENERALLY WORSE-THAN-EXPECTED
ACCUMULATING OVERNIGHT SNOW/SLEET (AND LIKELY AT LEAST BRIEF
FREEZING RAIN) ACROSS SEVERAL NORTHERN/WESTERN COUNTIES.
MEANWHILE...SEVERAL CENTRAL SOUTHEASTERN COUNTIES HAVE SEEN
NOTHING MORE THAN RAIN SHOWERS/A FEW EARLIER
THUNDERSTORMS...ALTHOUGH A GRADUAL TRANSITION TO SOME SLEET MIX
MAY BE GETTING UNDERWAY AT ANY TIME.

STARTING WITH A VERY BRIEF LOOK AT THE ONGOING SITUATION...WATER
VAPOR IMAGERY AND SHORT TERM MODEL DATA DEPICTS THE HEART OF THE
LONG-ANTICIPATED...VIGOROUS CLOSED MID LEVEL LOW OVER EAST-CENTRAL
KS...ALONG WITH A NEARLY VERTICALLY STACKED 1000 MILLIBAR SURFACE
LOW IN THE SAME AREA. WHILE THINGS PRETTY MUCH PANNED OUT EXPECTED
THROUGH THE FIRST HALF OF THE NIGHT...THESE LAST 2-3 HOURS
PROVIDED A BIT OF A SURPRISE VERSUS THE PREVIOUS FORECASTS AS THE
MOST CONCENTRATED AREA OF SNOW SET UP IN A NORTH-SOUTH BAND
GENERALLY 20-30 MILES EITHER SIDE OF THE HIGHWAY 183 CORRIDOR.
THIS NARROW BAND OF STEADIER SNOW CONTINUES AT THIS TIME...WITH
SEEMINGLY LIGHTER SNOW AFFECTING SEVERAL COUNTIES NORTH OF
INTERSTATE 80. ALTHOUGH AMOUNTS MAY HAVE GONE UP FARTHER SINCE
THEN...REPORTS AROUND AN HOUR AGO INDICATED A GENERAL 1-2 INCHES
ALREADY ON THE GROUND IN THE HOLDRGE/MINDEN AREAS...AND THIS
SUPPORTED BY RADAR DATA. THIS SNOW BAND IS CONCENTRATED IN THE
TYPICAL...BUT-OFTEN-DIFFICULT TO FORETELL DEFORMATION ZONE OF
LOW-MID LEVEL FRONTOGENESIS ALONG THE NORTHWEST QUADRANT OF THE
PARENT LOW.

GIVEN THAT SOME OF THE HIGHEST SNOW TOTALS SO FAR HAVE CLEARLY
FALLEN OUTSIDE THE ORIGINAL ADVISORY AREA...THE MAIN
ISSUE/CHALLENGE OVERNIGHT HAS BEEN PLAYING CATCH-UP...AND TACKING
ON A NUMBER OF WESTERN AND A FEW MORE NORTHERN COUNTIES TO
HOPEFULLY BETTER-CAPTURE ALL COUNTIES THAT AT LEAST HAVE THE BEST
POTENTIAL TO REACH OR FLIRT WITH THE 2-4 INCH RANGE.
HOWEVER...GIVEN HOW THINGS HAVE ALREADY FARED OVERNIGHT...CONFIDENCE
IS RATHER LOW.

BRIEFLY GOING OVER FORECAST EXPECTATIONS...AND LEANING TOWARD THE
RAP13 MODEL FOR THESE FIRST SEVERAL HOURS AS IT HAS DONE THE BEST
JOB WITH THE DEVELOPMENT OF THE WESTERN BAND...THE PARENT MID AND
LOW LEVEL LOW PRESSURE SYSTEMS ARE EXPECTED TO REACH WESTERN
PORTIONS OF THE IA/MO BORDER BY NOON...AND THEN SOUTH CENTRAL IA
BY SUNSET...BEFORE DEPARTING WELL-EASTWARD TO NEAR THE SOUTHERN
TIP OF LAKE MICHIGAN BY SUNRISE TUESDAY.

FOR THIS MORNING...EXPECT THE MOST-PROBLEMATIC WESTERN BAND TO
GRADUALLY DIMINISH IN INTENSITY AS IT SLOW PIVOTS EASTWARD.
ALTHOUGH ITS CERTAINLY POSSIBLE THAT FURTHER COUNTIES MAY NEED
ADDED TO THE ALREADY-GROWING ADVISORY...WILL HOLD OFF FOR NOW AND
LET DAY SHIFT MONITOR TRENDS/IMPACTS. BY THIS AFTERNOON EXPECT THE
MAJORITY OF ACCUMULATING SNOW FOCUS/HIGHEST POPS TO FOCUS NORTH OF
INTERSTATE 80...WHILE THE DEPARTING MOVEMENT OF THE SYSTEM ALLOWS
SOUTHERN/WESTERN COUNTIES TO SEE IMPROVING CONDITIONS. CERTAINLY
THE MAJORITY OF ISSUES SHOULD BE OVER BY 00Z/6PM WHICH HAPPENS TO
BE THE END OF THE ADVISORY TIME FOR NOW...BUT AT LEAST A FEW
TENTHS OF AN INCH OF ACCUMULATION COULD LINGER MAINLY IN
NORTHEASTERN ZONES INTO MAINLY THE 6-9 PM TIME FRAME...BEFORE ALL
PRECIPITATION ENDS FOR THE NIGHT...WITH RATHER HIGH CONFIDENCE IN
BEING PRECIP-FREE CWA-WIDE BY MIDNIGHT. OBVIOUSLY IN ADDITION TO
THE FALLING SNOW (AND MAYBE SOME SLEET THIS MORNING MAINLY
SOUTHEAST)...INCREASING NORTH-NORTHWEST WINDS BEHIND THE DEPARTING
LOW WILL BE AN ISSUE...AND IF ANYTHING BUMPED UP SPEEDS THIS
AFTERNOON/EVENING A FEW MORE MPH WITH SUSTAINED VALUES POSSIBLY
FLIRTING WITH 30 MPH AT TIMES/GUSTS TO AROUND 40 MPH...BEFORE
SLOWLY DIMINISHING OVERNIGHT...WITH SPEEDS BY SUNRISE TUESDAY
GENERALLY AVERAGING 10-15 MPH WEST AND 15-20 MPH EAST WITH HIGHER
GUSTS.

TEMP-WISE...TOOK A BEST STAB AT HOURLY TRENDS...AS ACTUAL HIGHS
ARE EXPECTED TO CLIMB VERY LITTLE IF ANY FROM VALUES THIS
MORNING...AND THUS WITH MOST OF THE CWA TOPPING OUT SOMEWHERE IN
THE LOW-MID 30S...WHICH ACCOMPANIED BY THE STRONG WINDS WILL
RESULT IN WIND CHILL VALUES GENERALLY IN THE TEENS TO LOW 20S FOR
MUCH OF THE DAY...MAKING FOR A NOTICEABLY END THE SPRING-LIKE
MILDNESS OF THE PAST FEW DAYS. FOR LOWS TONIGHT...STAYED CLOSER TO
A MODEL BLEND AND 00Z MET GUIDANCE WITH VALUES AIMED MAINLY INTO
THE 15-22 RANGE...AS THE PRESENCE OF LINGERING CLOUDS AND STEADY
BREEZES SHOULD KEEP VALUES ABOVE THE TOO-COLD LOOKING 00Z MAV
GUIDANCE.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 612 AM CST MON DEC 15 2014

THE BIGGEST CHALLENGE WILL BE DETERMINING CHANCES OF
PRECIPITATION WEDNESDAY NIGHT THROUGH FRIDAY NIGHT.

SHORTWAVE RIDGING WILL ENSURE A DRY FORECAST FOR TUESDAY INTO
WEDNESDAY. WE MAY FINALLY SEE THE SUN ON TUESDAY BEFORE MORE
CLOUDINESS TAKES OVER MID TO LATE WORK WEEK. A LONGWAVE TROUGH WILL
MOVE INTO THE WESTERN ROCKIES BY WEDNESDAY NIGHT AS ISENTROPIC LIFT
AHEAD OF THIS TROUGH DEVELOPS BY LATE WEDNESDAY NIGHT...GIVING US
POTENTIAL FOR SOME LIGHT SNOW. THE GFS DISPLAYS A PROMINENT DRY MID-
LEVEL FOR THURSDAY...SUGGESTING THE POTENTIAL FOR FREEZING DRIZZLE
JUDGING BY THE INVERTED SATURATED LOW-LEVEL TEMPERATURE AND
DEWPOINT PROFILE AND THE VEERING LOW-LEVEL WIND PROFILE. THE ECMWF
DOES NOT ADVERTISE THE ABSENCE OF MOISTURE IN THE DENDRITIC GROWTH
ZONE OR SHOW A PROMINENT DRY LAYER IN MID-LEVELS...SO I AM LEAVING
FREEZING DRIZZLE OUT FOR NOW AS THERE IS NOT GOOD AGREEMENT AMONG
NUMERICAL MODELS AND THIS IS FAIRLY FAR OUT IN TO THE FORECAST AS
WELL.

UNTIL THE TROUGH AXIS PASSES TO THE EAST...WE WILL HAVE SMALL
CHANCES OF PRECIPITATION...MAINLY SNOW.. WEDNESDAY NIGHT THROUGH
FRIDAY/FRIDAY NIGHT. NOT LOOKING FOR BIG SNOW AMOUNTS FOR NOW...AS
THE MAIN FOCUS OF ENERGY WITH THE WAVE WILL BE WELL SOUTH OF THE
CWA.

SATURDAY AND SUNDAY ARE FORECAST TO BE DRY IN THE SUBSIDENCE BEHIND
THE TROUGH. TEMPERATURES WILL BE FAIRLY SEASONABLE OVER THE WEEKEND
WITH HIGHS IN THE MID 30S TO NEAR 40 AND LOWS IN THE TEENS TO LOWER
20S. DID NOT MAKE ANY WHOLESALE CHANGES TO TEMPERATURES IN THE LONG
TERM.

&&

.AVIATION...(FOR THE 12Z KGRI/KEAR TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 649 AM CST MON DEC 15 2014

NEEDLESS TO SAY...THIS IS A LOW CONFIDENCE TAF PERIOD ESPECIALLY
WITH RESPECT TO PRECIPITATION TIMING...ALONG WITH CEILING
TRENDS. AT LEAST AS OF THIS MOMENT...KGRI HAS LIKELY YET TO SEE
ACCUMULATING SNOW...WHILE KEAR HAS SEEN AT LEAST A LIGHT DUSTING.
GIVEN THAT THE MAJORITY OF ACCUMULATING SNOW POTENTIAL SHOULD
FOCUS DURING THE MORNING HOURS...HAVE FOCUSED A TEMPO GROUP WITH
MVFR VISIBILITY AND IFR CEILING DURING THAT TIME...WHILE KEEPING
PREVAILING VFR VISIBILITY AND MVFR CEILING THROUGH THE MAJORITY OF
THE TAF PERIOD. ALTHOUGH CONFIDENCE IS LOW REGARDING WHEN CEILINGS
WILL RAISE/AND OR SCATTER TO VFR CATEGORY...HAVE TAKEN A STAB AT
IT LATE IN THE PERIOD. BARRING SIGNIFICANT CHANGES...STORM TOTAL
SNOW ACCUMULATION AT THE TAF SITES SHOULD AVERAGE UNDER 2
INCHES...AND POTENTIALLY WELL-BELOW THAT AT KGRI.
FORTUNATELY...CONFIDENCE IS REASONABLY HIGH IN SURFACE WIND
TRENDS...AS A FAIRLY CONSISTENT NORTH-NORTHWESTERLY DIRECTION WILL
PREVAIL THROUGH THE PERIOD WITH SUSTAINED SPEEDS INCREASING TO
GENERALLY 20-25KT AND FREQUENT GUSTS TO AROUND 30-35KT OR
HIGHER...ESPECIALLY THIS AFTERNOON AND EVENING...WITH SLOWLY-
DECREASING SPEEDS AS THE NIGHT WEARS ON.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR
     NEZ039>041-046-047-060-061-072>074-082>084.

KS...NONE.
&&

$$

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



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