Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 040611
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
1211 AM CST WED MAR 4 2015

.UPDATE...
ISSUED AT 1211 AM CST WED MAR 4 2015

ALTHOUGH SNOW AMOUNT EXPECTATIONS STILL REMAIN LARGELY ON TRACK
FROM PREVIOUS FORECAST (MEANING MAINLY BETWEEN 0.5 AND 1 INCH IN
MOST AREAS...WITH SOME LOCALIZED 1+ INCH POCKETS POSSIBLE
ESPECIALLY WITHIN OUR SOUTHWESTERN QUADRANT)...DID INCREASE POPS
CONSIDERABLY INTO THE 60-90 PERCENT RANGE TO BETTER ACKNOWLEDGE THE
OBVIOUS FACT THAT WIDESPREAD LIGHT TO BRIEFLY MODERATE SNOW HAS IN
FACT OVERSPREAD THE MAJORITY OF THE CWA ALREADY. THE MAIN AREA OF
SNOW SHOULD GRADUALLY SLIP SOUTH AND EAST THROUGH THE NIGHT...WITH
ALL BUT POSSIBLY THE FAR SOUTHERN CWA IN KANSAS LIKELY DONE WITH
ANY ACCUMULATION BEFORE SUNRISE.

UPDATE ISSUED AT 930 PM CST TUE MAR 3 2015

THE MAIN BAND(S) OF FRONTOGENETIC FORCING ARE FORMING AND MOVING
INTO THE CWA. THE INITIATION OF THESE BANDS IS A TAD FARTHER NORTH
THAN THE ORIGINAL FORECAST AND I HAVE MADE A SHIFT IN THE
FORECAST. STILL FORECAST TO SLIDE SOUTH. OUR BEST SHOT AT NEAR AN
INCH WILL BE WEST CENTRAL/SOUTHWESTERN CWA. ANYTHING FARTHER EAST
WILL TAKE AWHILE TO MOISTEN AND WILL HAVE LESS SNOWFALL.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 320 PM CST TUE MAR 3 2015

ALOFT: A LONGWAVE TROF EXTENDED FROM THE NRN ROCKIES SSW TO A
CLOSED LOW MOVING INTO BAJA CA. THIS TROF WILL GRADUALLY PROGRESS
E AND WILL MOVE INTO THE FCST AREA BY SUNSET TOMORROW...EXTENDING
FROM THE UPR MIDWEST TO NM. AN EMBEDDED SHORTWAVE TROF /BEST SEEN
AT 700 MB/ WAS OVER WY/UT. THIS TROF WILL MOVE INTO THE FCST AREA
TONIGHT AND WEAKEN IN THE CONFLUENT FLOW...BUT IT WILL STRENGTHEN
THE MID-LVL TEMP GRADIENT ON THE FRONTAL SURFACE...ENOUGH TO
PRODUCE LIFT/SATURATION.

SURFACE: AN ARCTIC COLD FRONT HAS SURGED ACROSS THE FCST AREA
TODAY. ARCTIC HIGH PRES OVER WRN CANADA WAS BUILDING IN AND WILL
SLIDE SE INTO THE NRN PLAINS TOMORROW. IT IS THIS FRONTAL SURFACE
THAT WILL BE STRENGTHENED ALOFT.

TONIGHT: ANY CLEARING THAT OCCURS THIS AFTERNOON WILL BE REPLACED
BY MORE CLOUDS AS A BAND OF MODERATE-STRONG FGEN FORMS IN THE MID-
LVLS AND DROPS ACROSS THE AREA.

MESOSCALE MODELS DEPICTS A BAND OF LIGHT SNOW DEVELOPING FROM CO
INTO SW NEB/NW KS 00Z-03Z...EXPANDING ACROSS PARTS OF THE FCST
AREA 03Z-09Z...AND THEN DIMINISHING AND/OR SINKING S 09Z-12Z.

NAM CROSS SECTIONS DO INDICATE SOME WEAK SYMMETRIC STABILITY. SO
THIS BAND HAS THE POTENTIAL TO OVER-PRODUCE OVER A VERY NARROW
AREA.

SNOW: DESPITE THIS BEING A MINOR EVENT...THE BUST POTENTIAL IS
HIGH. THESE TYPES OF NARROW BANDED EVENTS USUALLY HAVE VERY SHARP
GRADIENTS AND WHILE WE CAN HAVE MEDIUM-HIGH CONFIDENCE THEY WILL
OCCUR...CONFIDENCE IS USUALLY LOW ON WHERE AND HOW MUCH SNOW WILL
FALL.

ACCUM: THE COLUMN WILL BE COLD. SO USED A 20:1 SNOW:LIQUID RATIO
AND THAT MAY NOT BE HIGH ENOUGH. USING A 50-50 BLEND OF THE
06Z/12Z MODELS...THE FCST HAS AROUND 1" S AND W OF HASTINGS WITH A
MAX OF 1.5" OVER FURNAS/HARLAN COUNTIES. THIS IS NOT GOSPEL. IT
WILL DEPEND WHERE THE BAND FORMS AND LINGERS THE LONGEST. WOULD
NOT BE SURPRISED TO SEE AN ISOLATED 3" AMT SOMEWHERE.

THE DENDRITIC GROWTH ZONE WILL BE DEEP! ROUGHLY 10K FT.

NOT AS EASY CALL ON LOW TEMPS. MULTI-MODEL 2M TEMPS USUALLY
VERIFY BEST IN THESE CLOUDY NIGHTTIME SITUATIONS...AND MOS IS
USUALLY TOO COLD. COULD NOT GO AS WARM AS I WANTED TO...BUT USED A
BLEND OF THE MODEL 2M TEMPS AND THE PREVIOUS FCST WITH A BIAS
CORRECTION. THAT DID INCREASE TEMPS A LITTLE...ESPECIALLY N OF HWY
6.

WED: ANY LEFTOVER SNOW OVER N-CNTRL KS WILL END. MULTI-MODEL
CROSS SECTIONS STILL SHOW CONSIDERABLE MID-LVL RH REMAINING. SO
SKIES PROBABLY WONT BEGIN TO CLEAR MOST AREAS UNTIL AFTERNOON.
USED BIAS CORRECTED CONSENSUS OF MODEL 2M TEMPS FOR HIGHS /26-32F
WITH UPR 20S IN THE TRI-CITIES/. THIS IS 15F COLDER THAN NORMAL.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 320 PM CST TUE MAR 3 2015

AN UPPER LEVEL TROUGH MOVES THROUGH THE AREA WEDNESDAY NIGHT AND
A SURFACE LOW MOVES TO THE SOUTH TO THE EAST OF THE FORECAST AREA.
COLD AIR CONTINUES TO PUSH INTO THE AREA WEDNESDAY NIGHT AND LOWS
IN THE SINGLE DIGITS ARE EXPECTED.

ONCE THE SURFACE HIGH MOVES OFF TO THE EAST EARLY THURSDAY...
THERE WILL BE WARM ADVECTION AND TEMPERATURES RISE RAPIDLY ALOFT.
TEMPERATURES DURING THE DAY THURSDAY WILL STILL BE A LITTLE BELOW
NORMAL FOR THIS TIME OF YEAR...BUT MUCH WARMER THAN WEDNESDAY.

NORTHWEST FLOW CONTINUES ACROSS THE AREA THROUGH THE WEEKEND AND
INTO EARLY NEXT WEEK. THERE ARE A FEW FAIRLY WEAK WAVES THAT MOVE
THROUGH THE AREA. NONE OF THEM ARE VERY STRONG AND AT MOST EXPECT
A FEW CLOUDS TO MOVE THROUGH. THERE IS A WEAK COLD FRONT FRIDAY
NIGHT WITH AN UPPER WAVE THAT IS MAINLY TO THE NORTHEAST OF THE
AREA. THIS COULD BRING A FEW ADDITIONAL CLOUDS TO THE AREA FOR
SATURDAY AND A LITTLE COOLER TEMPERATURES BUT ONLY A COUPLE OF
DEGREES.

&&

.AVIATION...(FOR THE 06Z KGRI/KEAR TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1210 AM CST TUE MAR 3 2015

BY FAR THE MAIN ISSUE DURING THE PERIOD INVOLVES THESE FIRST
3-6 HOURS RIGHT OFF THE BAT EARLY THIS MORNING...AS A BROAD BAND
OF GENERALLY LIGHT TO MODERATE SNOW SHIFTS EAST-SOUTHEAST ACROSS
THE AREA. HAVE GONE WITH A 2-HOUR TEMPO GROUP OF MVFR/IFR
VISIBILITY AND MVFR CEILING TO CAPTURE THE HEIGHT OF THE
SNOWFALL...BUT BRIEFLY-WORSE CONDITIONS ARE CERTAINLY POSSIBLE.
SNOW SHOULD LARGELY BE OVER WITH BY 09Z...BUT COULD SEE AN MVFR
CEILING HANG ON A FEW MORE HOURS...AND AM TENTATIVELY AIMING FOR A
RETURN TO VFR BY 11Z. THEREAFTER THROUGH THE REMAINDER OF THE
PERIOD...CONFIDENCE IS FAIRLY HIGH IN VFR CEILING/VISIBILITY WITH
ONLY SOME MID LEVEL CLOUDS. WIND-WISE...A GENERALLY NORTHERLY
DIRECTION WILL HOLD FIRM THROUGHOUT THE PERIOD...WITH SPEEDS THIS
MORNING AVERAGING NEAR/BELOW 10KT...THEN INCREASING DURING THE DAY
WITH GUST POTENTIAL INTO THE 20-25KT RANGE...BEFORE FALLING OFF
CONSIDERABLY THIS EVENING.

&&

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

$$

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


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