Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 020558
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
1258 AM CDT WED SEP 2 2015

.UPDATE...
ISSUED AT 1258 AM CDT WED SEP 2 2015

FOR THE REST OF TONIGHT: ALTHOUGH THE VAST MAJORITY OF THE CWA
STANDS A GOOD CHANCE OF STAYING DRY...WILL GO WITH SOME "IFFY" 20
PERCENT CHANCES (POPS) FOR SHOWERS/STORMS WITHIN BOTH THE
NORTHEASTERN AND SOUTHEASTERN QUADRANTS OF THE CWA. CERTAINLY THE
MAIN FOCUS FOR OVERNIGHT CONVECTION LOOKS TO BE IN THE NEB/KS/MO
BORDER AREA TO OUR EAST WITHIN THE PRIMARY EXIT REGION OF A
NOCTURNALLY VEERING LOW LEVEL JET...BUT EVEN WITHIN THE PAST HOUR
A TINY ROGUE SHOWER POPPED UP NEAR GRAND ISLAND NEAR THE WESTERN
EDGE OF THIS LEVEL JET AXIS...SO SOME VERY SPOTTY ACTIVITY JUST
CANNOT BE RULED OUT.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 323 PM CDT TUE SEP 1 2015

THE PATTERN ALOFT FEATURED SOUTHWEST FLOW ACROSS THE CENTRAL PLAINS
WITH RIDGING TO THE SOUTH WHILE AN UPPER LOW PRESSURE SYSTEM WAS
JUST OFF SHORE NEAR BRITISH COLUMBIA. A MID LEVEL SHORTWAVE TROUGH
WAS SLOWLY TRANSLATING ACROSS THE CENTRAL PLAINS AND GENERATED
HIT OR MISS CONVECTION EARLIER THIS MORNING. THE MID LEVEL
SHORTWAVE TROUGH IS EXPECTED TO LIFT OUT THIS EVENING...THEN
ANOTHER ROUND OF ISOLATED TO SCATTERED CONVECTION IS POSSIBLE
TONIGHT AS THE LLVL JET STRENGTHENS TO 40KTS. THE ORIENTATION OF
THE JET AXIS PLACES THE BETTER CHCS FOR CONVECTION ALONG OUR
SOUTHERN AND EASTERN ZONES. THE ELEVATED INSTABILITY IS RATHER
MEAGER...NEAR 1000 J/KG AND ALTHOUGH EXPECT THUNDER JUST NOT
LOOKING FOR ANYTHING TO BE SEVERE.

WEDNESDAY COULD SEE A FEW LINGERING SHOWERS OR STORMS IN THE
MORNING...THEN CONDITIONS DRY OUT FOR THE REMAINDER OF THE DAY.
SOUTHERLY WIND SPEEDS RAMP UP AS MIXING DEEPENS AND THE SFC GRADIENT
TIGHTENS. MODEL FORECAST SOUNDINGS INDICATE MIXING ABOVE H85 WITH
WINDS AT THE TOP OF THE LAYER NEAR 30KTS...AND RESULTANT SFC WINDS
ARE EXPECTED TO BE SOUTHERLY AT 20 TO 25 MPH WITH GUSTS OF 30 MPH.
THE STRONGEST WINDS ARE FORECAST FOR OUR SOUTHERN AND EASTERN ZONES
WHERE GRADIENT WILL BE TIGHTER...WHILE THE WESTERN AREAS WILL BE
CLOSER TO THE WESTERN SURFACE TROUGH BOUNDARY. HIGH TEMPERATURES
WILL AGAIN BE ABOVE NORMAL WITH READINGS IN OR NEAR THE 90S...AND
ALSO EXPECT SOME DEGREE OF CLOUD COVER FM MORNING CONVECTION AND
ALSO AS UPPER JET STREAK CROSSES.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 323 PM CDT TUE SEP 1 2015

PRIMARY FORECAST CONCERN THROUGH THE LONG TERM LIES WITH
PRECIPITATION CHANCES.

MODELS SHOWING ZONAL/SLIGHT SWRLY UPPER LEVEL FLOW ACROSS THE AREA
AT THE START OF THE PERIOD WEDNESDAY NIGHT...WITH HIGH PRESSURE
CENTERED OVER WRN TX INTO THE SRN PLAINS...WITH AN AREA OF LOW
PRESSURE OVER THE SWRN COAST OF CANADA AND ACCOMPANYING TROUGH
EXTENDING DOWN THE WEST COAST OF THE US. AT THE SFC...THE CWA
CONTINUES TO SIT WITH SRLY WINDS IN PLACE...AS A TROUGH OF LOW
PRESSURE EXTENDS THROUGH THE HIGH PLAINS. INHERITED A SLIGHT CHANCE
MENTION OF A FEW THUNDERSTORMS IN THE 06-12Z PERIOD WED NIGHT/EARLY
THURS MORNING...AND DEBATED REMOVING THE MENTION...BUT A FEW MODELS
CONTINUE TO SHOW THE POTENTIAL WITH THE PASSAGE OF A VERY WEAK WAVE
AND AN INCREASED LLJ NOSING INTO THE REGION. DID TRIM BACK THE AREA
OF POPS TO FAR SERN PORTIONS OF THE CWA. ANY THUNDERSTORMS THAT DO
DEVELOP ARE NOT EXPECTED TO BE SEVERE.

DURING THE DAYTIME HOURS ON THURSDAY...DID KEEP THE FORECAST
DRY...BUT MODELS ARE SHOWING THE UPPER LEVEL PATTERN BECOMING MORE
AMPLIFIED ACROSS THE CONUS...AS THAT UPPER LEVEL LOW AND TROUGH DIG
FURTHER SOUTH INTO THE PAC NW AND WEST COAST. THE MAIN RIDGE AXIS
PUSHES FURTHER NORTH...REACHING FROM THE SRN PLAINS INTO THE WRN
GREAT LAKES...LEAVING SHARPER SWRLY FLOW IN PLACE ACROSS THE CENTRAL
PLAINS. AT THE SFC...THERE DOESNT LOOK TO BE A LOT OF CHANGE...WITH
THE CWA REMAINING ON THE ERN SIDE OF LOW PRESSURE/TROUGH
AXIS...KEEPING WINDS SRLY.

THROUGH THE REST OF THE LONG TERM PERIOD...THURS NIGHT THROUGH
MONDAY...THE POTENTIAL IS THERE FOR MORE OF AN UNSETTLED PATTERN.
THE MORE AMPLIFIED PATTERN LOOKS TO REMAIN IN PLACE WELL INTO THE
WEEKEND...AS THAT PAC NW LOW DIGS A LITTLE FURTHER SOUTH...ENDING UP
ROUGHLY OVER SRN IDAHO BY 00Z SUN. SUN/MON...MODELS SHOW THIS SYSTEM
THEN TAKING A MORE NERLY TURN...PASSING THROUGH THE ROCKIES AND BY
MONDAY MORNING IS LOCATED NEAR THE ND/CAN BORDER. PERIODIC SHORTWAVE
DISTURBANCES OUT AHEAD OF THIS SYSTEM...AND WITH THIS SYSTEM
ITSELF...WILL BRING OPPORTUNITIES FOR PRECIPITATION. HAVE POPS GOING
IN EACH PERIOD THURS NIGHT THROUGH MONDAY...BUT KEPT THEM IN THE 20-
30 PERCENT RANGE...AS CONFIDENCE IN TIMING/LOCATION/OVERALL COVERAGE
IS NOT HIGH...BUT IN THE COMING DAYS EXPECTING THERE TO BE SOME
PERIOD DRIED OUT.

AS FAR AS TEMPERATURES GO...NO SIGNIFICANT CHANGES WERE MADE...WITH
MOST DAYS IN THE MID 80S TO MID 90S. THE END OF THE PERIOD ON MONDAY
HAS MORE UNCERTAINTY...AS MODELS TRYING TO SHOW A COLD FRONTAL
PASSAGE WITH THE MAIN UPPER LEVEL SYSTEM PUSHING THROUGH...DROPPING
THINGS INTO THE 70S/80S.

&&

.AVIATION...(FOR THE 06Z KGRI/KEAR TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1258 AM CDT WED SEP 2 2015

CONFIDENCE REMAINS HIGH IN VFR CEILING/VISIBILITY THROUGH THE
PERIOD...WITH ONLY A LIMITED COVERAGE OF HIGH AND POSSIBLY MID
CLOUDS FROM TIME TO TIME. ALTHOUGH THE RISK OF A BRIEF
SHOWER/THUNDERSTORM IS NOT TRULY "ZERO"...IT IS FAR TOO LOW TO
JUSTIFY EVEN A "VICINITY" MENTION. THAT LEAVES LOW LEVEL WIND
SHEAR (LLWS) AS THE MAIN ISSUE...THROUGH BOTH THESE FIRST FEW
HOURS EARLY THIS MORNING...AND THEN POSSIBLY AGAIN TOWARD THE END
OF THE PERIOD WEDNESDAY NIGHT. FOR NOW...WILL NOT INSERT ANY LLWS
CONCERNS FOR LATE IN THE PERIOD AND WILL DEFER TO LATER TAF
ISSUANCES TO ADDRESS.

HOWEVER...FOR THE ONGOING/IMMINENT ROUND OF LLWS THIS
MORNING...WILL MAINTAIN 5 HOURS OF FORMAL MENTION AT KGRI THROUGH
11Z...AS WINDS WITHIN THE LOWEST 1000 FT AGL QUICKLY ACCELERATE
TO AROUND 40KT FROM THE SOUTH-SOUTHWEST...CREATING ROUGHLY 30-35
KNOTS OF BULK SHEAR DIFFERENCE BETWEEN THE SURFACE AND THIS LEVEL.
HOWEVER...AT KEAR...HAVE REMOVED ANY MENTION OF LLWS AS THIS SITE
APPEARS TO BE JUST FAR ENOUGH WEST TO LARGELY KEEP OVERALL-BULK
SHEAR IN THE LOWEST 1000 FT BELOW 30KT.

AS FOR SURFACE WIND...BOTH THIS MORNING AND AGAIN THIS EVENING
SHOULD SEE SOUTHERLY WIND SPEEDS ONLY AROUND 10KT...ALTHOUGH THE
AFTERNOON HOURS WILL SEE INCREASED SPEEDS WITH GUST POTENTIAL UP
TO AROUND 20KT.

&&

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

$$

UPDATE...PFANNKUCH
SHORT TERM...FAY
LONG TERM...ADP
AVIATION...PFANNKUCH



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