Area Forecast Discussion
Issued by NWS Hastings, NE

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000
FXUS63 KGID 262023
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
323 PM CDT WED AUG 26 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 305 PM CDT WED AUG 26 2015

FOCUS WILL BE ON THE APPROACHING SURFACE LOW TOMORROW WHICH WILL
RESULT IN AN INCREASE CHANCE FOR THUNDERSTORMS TOMORROW
AFTERNOON...SOME OF WHICH COULD BE ON THE STRONG SIDE WITH HAIL AND
WIND BEING THE MAIN THREAT.

IN THE UPPER LEVELS...THERE IS A RIDGE CENTERED OVER THE CONUS WHICH
IS SPLITTING TWO TROUGHS. THE TROUGH TO THE WEST WILL REMAIN
MOSTLY STATIONARY OVER NORTHEASTERN PARTS OF THE PACIFIC THROUGH
THE SHORT TERM PERIOD. AN EMBEDDED SHORT WAVE WILL EJECT OFF THE
ROCKIES AND RIDE OVER THE UPPER LEVEL RIDGE OVER THE CENTRAL
PLAINS TOMORROW. THIS FEATURE WILL RESULT IN A SURFACE LOW THAT
WILL STRENGTHEN AND GENERALLY MOVE IN AN EASTWARD FASHION THROUGH
THURSDAY. THERE WILL BE A COLD FRONT AND WARM FRONT ASSOCIATED
WITH THIS SURFACE LOW THAT WILL RESULT IN THE TRIGGERING
MECHANISM. THE CAP SHOULD DETERIORATE EARLY AFTERNOON TOMORROW AND
THERE WILL BE MUCAPE VALUES IN PLACE RANGING BETWEEN MOSTLY
1000-3000 J/KG. THE NAM BEING OVERALL THE STRONGEST IN THIS
SITUATION WHEN COMPARED TO THE GFS AND THE EUROPEAN. VEERING WIND
CONDITIONS...MID LEVEL LAPSE RATES AROUND 6-8 C/KM...AND SHEAR
VALUES FROM 0-6 KM WILL BE AROUND 20-40 KNOTS...SO THERE WILL BE A
CHANCE FOR ROTATING UPDRAFTS THAT COULD PRODUCED STRONG STORMS.
MAIN TREATS WILL BE WIND AROUND 50 MPH AND HAIL MAINLY AROUND
NICKEL TO QUARTER SIZE. LOW LEVEL HELICITY VALUES RANGE WIDELY
BETWEEN THE GFS...NAM AND EC...BUT THERE COULD BE A FEW VERY BRIEF
TORNADOES GIVEN ALL THESE PARAMETERS MENTIONED ABOVE. THERE IS
ALSO A SMALL CHANCE SOME LOCALIZED AREAS COULD HIGH RAINFALL
AMOUNTS WHERE STORMS ARE NOT MOVING FAST DUE TO WEAK UPPER LEVEL
MEAN FLOW. THE DIFFICULTY IN FORECASTING THIS IS VERY HIGH AND TOO
MUCH UNCERTAINTY EXISTS ABOUT QPF AMOUNTS FOR TOMORROW.

TEMPERATURES TONIGHT WILL BE ABOVE NORMAL WITH VALUES RANGING
BETWEEN THE UPPER 60S AND LOWER 70S. TOMORROWS HIGHS WILL BE RIGHT
AROUND NORMAL TO SLIGHTLY ABOVE NORMAL...RANGING BETWEEN THE MID
80S AND LOWER 90S.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 305 PM CDT WED AUG 26 2015

EXPECTING THUNDERSTORM ACTIVITY TO BE ONGOING AT THE START OF THE
LONG TERM PERIOD THURSDAY EVENING...WITH MODELS IN GOOD AGREEMENT
SHOWING THE MAIN UPPER LEVEL SYSTEM MOVING BASICALLY RIGHT ALONG THE
NEB/SD STATE LINE. THUNDERSTORMS ARE EXPECTED TO HAVE DEVELOPED
ALONG THE ACCOMPANYING SFC FRONTAL BOUNDARY...WHICH MODELS SHOW
BEING ABOUT HALFWAY THROUGH THE CWA BY AROUND MIDNIGHT...AND MAKING
IT TO ROUGHLY THE HIGHWAY 81 CORRIDOR BY SUNRISE FRIDAY. MADE A FEW
MINOR ADJUSTMENTS TO EVENING/OVERNIGHT POPS...WHICH WERE ALREADY IN
THE LIKELY CATEGORY FOR CENTRAL/ERN PORTIONS OF THE CWA 00-6Z...WITH
A GRADUAL WEST TO EAST DOWNWARD TREND 06-12Z. INSTABILITY VALUES
LOOK TO WANE SOME WITH TIME COMPARED TO THE PEAK HEATING HOURS...AND
DEEPER LAYER SHEAR VALUES ARE NOT OVERLY IMPRESSIVE...BUT FORCING IS
GOOD WITH THE UPPER LEVEL SYSTEM MOVING THROUGH ALONG WITH AN SWRLY
LLJ EXPECTED TO INCREASE INTO THE 40-50KT RANGE...AND CANT RULE OUT
SOME STRONG/SEVERE THUNDERSTORMS LINGERING THROUGH MAINLY THE
EVENING HOURS.

SOME UNCERTAINTY IN EXACTLY WHEN THINGS WIND DOWN FOR OUR CWA...A
FEW MODELS HANG ONTO LINGERING ACTIVITY A BIT LONGER THAN
OTHERS...CURRENT FORECAST KEEPS 20 POPS IN PLACE ACROSS ERN PORTIONS
THROUGH THE MID MORNING HOURS FRIDAY. THE REMAINDER OF THE DAY IS
EXPECTED TO BE DRY...AS NORTHWESTERLY FLOW SETS UP IN THE UPPER
LEVELS BETWEEN THE DEPARTING SYSTEM AND RIDGING THROUGH THE ROCKIES.
AT THE SFC...THE MAIN FRONT CONTINUES WORKING ITS WAY EAST...WITH
BREEZY N/NWRLY WINDS EXPECTED THROUGH MUCH OF THE DAY BEFORE THE
PRESSURE GRADIENT STARTS TO RELAX CLOSER TO EVENING. HIGH TEMPS LOOK
TO BE COOLER...FORECAST TO RANGE FROM THE UPPER 70S IN THE NORTHEAST
TO MID 80S IN THE SW.

LOOKING AHEAD TO THE UPCOMING WEEKEND AND INTO THE FIRST FEW DAYS OF
THE NEXT WORK WEEK...KEPT THE FORECAST DRY...WITH MODELS IN FAIRLY
GOOD AGREEMENT SHOWING UPPER LEVEL RIDGING BEING THE PRIMARY FEATURE
TO AFFECT THE AREA. THROUGH THE WEEKEND THE PATTERN BECOMES MORE
AMPLIFIED...WITH THE RIDGE AXIS EXTENDING WELL NORTH INTO CENTRAL
PORTIONS OF CANADA BY SUNDAY MORNING...SET UP BETWEEN TROUGHS
LOCATED OVER THE ERN CONUS AND ALONG THE WEST COAST. AS THE WEST
COAST SYSTEM CONTINUES PUSHING EAST WITH TIME...THE RIDGE AXIS
BECOMES MORE ORIENTED SW TO NE...RIGHT THROUGH THE CENTRAL PLAINS.
NO SIGNIFICANT CHANGES WERE MADE TO TEMPERATURES THROUGH THIS
PERIOD...REMAINING IN THE 80S FOR MOST LOCATIONS...LOWER 90S
POSSIBLE MAINLY ACROSS NC KS.

&&

.AVIATION...(FOR THE 18Z KGRI/KEAR TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1239 PM CDT WED AUG 26 2015

VFR CONDITIONS ARE EXPECTED AT BOTH THE TERMINALS THROUGHOUT THE
VALID TAF PERIOD. CONFIDENCE IS PRETTY HIGH WITH THIS FORECAST.
ONE CONCERN IS WE COULD SEE SOME CEILINGS AROUND 1000-3000 FT
(MVFR CONDITIONS) TOMORROW MORNING...BUT CONFIDENCE WAS NOT HIGH
ENOUGH TO GO QUITE THAT LOW ON CEILINGS AT THIS TIME. THE OTHER
AREA OF CONCERN REVOLVES AROUND SURFACE WINDS AND THEN A CHANCE
FOR LOW LEVEL WIND SHEAR TOMORROW MORNING. FIRST...WIND SPEEDS
SHOULD PICK UP LATER THIS AFTERNOON TO AROUND 15 KNOTS WITH GUSTS
CLOSER TO 20-25 KNOTS. WIND SPEEDS WILL DECREASE TONIGHT AROUND
00Z. WIND SPEEDS WILL AGAIN PICK BACK UP TOMORROW AFTERNOON TO
AROUND 15 KNOTS AHEAD OF A STRENGTHENING LOW AT THE SURFACE...BUT
GUSTS COULD BE CLOSER TO 25 KNOTS. DEPENDING ON THIS SURFACE LOW
TRACK...WIND SPEEDS COULD CHANGE IN BOTH MAGNITUDE AND DIRECTION
SO KEEP AN EYE ON THAT FOR TOMORROW. LASTLY...IT DOES APPEAR THERE
WILL BE A CHANCE FOR LOW LEVEL WIND SHEAR TOMORROW MORNING AS A
LOW LEVEL JET NOSES INTO THE FORECAST AREA AHEAD OF THE SURFACE
LOW. CONFIDENCE IN TIMING AND INTENSITY IS STILL A LITTLE
UNCERTAIN SO LOOK FOR POSSIBLE CHANGES IN SUBSEQUENT TAFS FOR
LLWS.

&&

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

$$

SHORT TERM...GUERRERO
LONG TERM...ADP
AVIATION...GUERRERO


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