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000
FXUS63 KGID 170520
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
1220 AM CDT FRI MAY 17 2013

.UPDATE...
ISSUED AT 917 PM CDT THU MAY 16 2013

CONVECTIVE ACTIVITY HAS WEAKENED ACROSS THE AREA THROUGH THE PAST
COUPLE OF HOURS. ALTHOUGH A FEW ISOLATED THUNDERSTORMS
REMAIN...THE LOSS OF DIABATIC HEATING AS SIGNIFICANTLY REDUCED
POTENTIAL INSTABILITY ACROSS THE AREA AND AS A RESULT...SEVERE
WEATHER IS NO LONGER EXPECTED. THE SEVERE THUNDERSTORM WATCH WAS
ALLOWED TO EXPIRE AT 8 PM AS A RESULT. SHORT-TERM GUIDANCE DOES
SUGGEST A FEW ISOLATED THUNDERSTORMS WILL REMAIN POSSIBLE THIS
EVENING AND WILL MAINTAIN SUCH WORDING IN THE FORECAST AND HWO AS
A RESULT. OVERALL THE FORECAST REMAINS IN GREAT SHAPE...WITH ONLY
A FEW TWEAKS MADE TO HOURLY TEMPERATURE...DEWPOINT...SKY AND WIND
GRIDS TO BETTER REFLECT CURRENT CONDITIONS.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 403 PM CDT THU MAY 16 2013

CONVECTION THAT WAS MOVING INTO THE CWA THIS MORNING HAS LONG DRIED
UP...WITH THE AREA OF CONVECTION IN NORTHEASTERN NEBRASKA NEAR THE
WARM FRONT AND WILL CONTINUE TO MOVE EAST-NORTHEAST ALONG THE
INSTABILITY AXIS AND EAST OF OUR AREA.

THE NEXT AREA OF CONCERN IS THE AREA OF CONVECTION TO THE WEST OF
THE CWA THIS AFTERNOON...ASSOCIATED WITH A MID-LEVEL PERTURBATION
MOVING INTO THE CENTRAL PLAINS. SHEAR IS WEAK TO PERHAPS
MODERATE...WITH CAPES OF 1500-2000 J/KG. THIS COMBINATION COULD
POSSIBLY BE ENOUGH TO SUSTAIN MARGINALLY SEVERE WEATHER INTO THE
EARLY EVENING...BUT WHEN THE SUN SETS...INSTABILITY WILL
DECREASE...WITH THE LOW-LEVEL JET SETTING UP WEST OF THE
CWA...EXPECT ANY CONVECTION LEFT TO DIE OUT DURING THE
EVENING...PROBABLY NOT MAKING IT EAST OF THE CWA DUE TO LACK OF
SUPPORT. MODELS ARE CONTINUING TO BE DISPARATE AND INEPT IN
PREDICTING THE CONVECTION AS OF LATE...AND ARE OF LITTLE IF ANY HELP.

MODELS AND ENSEMBLES ARE INDICATING THAT WE COULD GET SOME PATCHY
FOG TONIGHT...BUT THE SIGNAL IS NOT TERRIBLY STRONG. WITH HIGHER
DEWPOINTS...I WOULD NOT BE SURPRISED TO HAVE SOMEWHAT REDUCED
VISIBILITY.

DEPENDING ON SYNOPTIC FEATURES FOR THE SHORT TERM FORECAST AS MODELS
HAVE NOT BEEN MUCH HELP WITH DETERMINE MESOSCALE FEATURES. WITH
A RIDGE BUILDING IN FOR FRIDAY I SEE LITTLE CHANCE OF ANY
PRECIPITATION...SO LEAVING THIS DRY. ADJUSTED TEMPERATURES SLIGHTLY
BASED ON RECENT MODEL PERFORMANCE AND BIAS CORRECTED MODELS.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 403 PM CDT THU MAY 16 2013

FRIDAY NIGHT THROUGH THURSDAY. MAIN FORECAST CONCERNS
WILL BE THUNDERSTORM CHANCES FOR SATURDAY AFTERNOON THROUGH TUESDAY
AND AGAIN WEDNESDAY NIGHT AND THURSDAY...AND TEMPERATURES THROUGH
THE PERIOD.

AN UPPER LEVEL RIDGE SLIDES TO THE EAST FRIDAY NIGHT WITH A SURFACE
WARM FRONT WELL NORTH OF THE FORECAST AREA. THIS WILL KEEP
TEMPERATURES ON THE WARM SIDE FOR THE NIGHT. THERE WILL ALSO BE AN
INCREASE IN MOISTURE DURING THE NIGHT. ON SATURDAY A COLD FRONT
DEVELOPS TO THE WEST OF THE AREA. MOIST AIR CONTINUES TO PUSH INTO
THE FORECAST AREA DURING THE DAY ON THE SOUTH WINDS. TEMPERATURES
WILL REMAIN ON THE WARM SIDE FOR SATURDAY. AN UPPER LEVEL WAVE
STARTS TO AFFECT THE AREA SATURDAY AFTERNOON AND THUNDERSTORM
CHANCES INCREASE DURING THE AFTERNOON. MUCAPE VALUES OF AROUND 5000
J/KG ARE FOUND DURING THE AFTERNOON ACROSS THE FORECAST AREA. THE
THUNDERSTORMS CONTINUE INTO THE EVENING. THE MUCAPE DECREASES DURING
THE EVENING AND MOST OF THE THUNDERSTORMS SHOULD START TO DIMINISH
DURING THE OVERNIGHT HOURS.

A COLD FRONT WILL MOVE THROUGH THE AREA SATURDAY NIGHT INTO SUNDAY.
BY SUNDAY TEMPERATURES WILL BE COOLER BEHIND THE FRONT. AN UPPER
LEVEL LOW SETTLES IN JUST TO THE NORTH OF THE FORECAST AREA ON
SUNDAY. THIS UPPER LEVEL LOW WILL DRIFT TO THE EAST THROUGH TUESDAY
AND BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS TO THE AREA DURING
THIS TIME. THE BEST CHANCE FOR SOME THUNDERSTORMS DURING THIS PERIOD
WILL BE SUNDAY AFTERNOON AND EVENING. THERE IS SOME POTENTIAL FOR
THUNDERSTORM CHANCES TO DIMINISH FOR SUNDAY MORNING...BUT THE MODELS
HAVE SOME DIFFERENCES AND THE TIMING IS A BIT UNCERTAIN.
TEMPERATURES WILL BE BACK AROUND NORMAL FOR THIS TIME OF YEAR FOR
MONDAY AND TUESDAY WITH ON AND OFF THUNDERSTORMS.

FOR MID WEEK...ANOTHER RIDGE BUILDS BEHIND THE UPPER LEVEL LOW AS IT
MOVES TO THE EAST. MODELS HAVE SOME DIFFERENCES IN THE AMPLITUDE OF
THE RIDGE. BOTH THE GFS AND THE ECMWF HAVE SOME INDICATIONS THERE
MAY BE A WEAK UPPER LEVEL WAVE THAT MOVES THROUGH THE RIDGE. THERE
WILL BE A SMALL CHANCE FOR THUNDERSTORMS FOR WEDNESDAY NIGHT INTO
THURSDAY WITH THIS WEAK UPPER LEVEL WAVE. THE RIDGE AND WARM
ADVECTION WILL BRING A WARMING TREND TO TEMPERATURES FOR WEDNESDAY
AND THURSDAY.

&&

.AVIATION...(FOR THE 06Z KGRI TAF THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1220 AM CDT FRI MAY 17 2013

VFR CONDITIONS ARE EXPECTED TO PREVAIL AT KGRI FOR THE NEXT 24
HOURS. EXPECT THE MID LEVEL CLOUD DECK COVERING MUCH OF NEBRASKA
THIS EVENING...TO GRADUALLY CLEAR OVERNIGHT AS A SHORT WAVE RIDE
TRANSITIONS ACROSS THE PLAINS. THIS SHOULD PUT AN END TO ANY
REMAINING SHOWER ACTIVITY AS WELL. WHILE WINDS WILL HAVE A SLIGHT
SOUTHEASTERLY COMPONENT AND DEWPOINTS WILL REMAIN ELEVATED
OVERNIGHT...MAY SEE SOME PATCHY FOG DEVELOPMENT AS INDICATED BY
SOME OF GUIDANCE...BUT CONFIDENCE OF THIS IS LOW...AND DID NOT
INCLUDE IN TAF. OTHERWISE...EXPECT A SURFACE TROUGH OF LOW
PRESSURE TO DEVELOP TO THE WEST TOMORROW AFTERNOON...AND THIS
SHOULD HELP TO TIGHTEN UP THE PRESSURE GRADIENT...SO WENT AHEAD
AND INCLUDED WIND GUSTS INTO THE LOWER 20S TOMORROW AFTERNOON.

&&

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

$$

UPDATE...BRYANT
SHORT TERM...HEINLEIN
LONG TERM...JCB
AVIATION...SAR