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000
FXUS63 KOAX 170006
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
706 PM CDT SUN JUN 16 2013

.UPDATE...
UPDATED THE FORECAST LATE IN THE AFTERNOON TO INCREASE POPS IN
NORTHEAST NEBRASKA AND INTO PARTS OF EASTERN NEBRASKA DUE TO RADAR
TRENDS...WEAK SHORTWAVE IN NORTHWEST FLOW AND POOLING OF H7
MOISTURE ALONG WITH SOME H85 WAA OVERNIGHT AND RETURN OF H85
MOISTURE.

&&

.DISCUSSION...
LINE OF SHOWERS AND THUNDERSTORMS MOVED INTO NORTHEAST NEBRASKA
DURING THE LATE AFTERNOON. SEVERE STORM TRENDS SHOULD CONTINUE TO
FOCUS TO OUR WEST...HOWEVER SOME SHOWERS AND THUNDERSTORMS SHOULD
MAKE IT INTO PARTS OF EASTERN NEBRASKA. A FEW SHOWERS COULD
CONTINUE TO PUSH EASTWARD OVERNIGHT WITH THE SHORTWAVE...HOWEVER
LEFT COVERAGE AS ISOLATED AS ALL SHORT TERM MODEL TRENDS ARE
MAINLY DRY.

&&

.AVIATION...
VFR CIGS THIS EVENING WITH CONVECTIVE DEBRIS. TSRA MOSTLY SOUTH OR
WEST OF KOFK...ISOLATED SHOWERS WITH CB AT KOFK EARLY IN THE TAF
PERIOD. A FEW SHOWERS COULD ALSO MAKE IT TO KOMA AND KLNK...BUT
CONFIDENCE TOO LOW TO MENTION TSRA AT THIS TIME. SHOWER ACTIVITY
MAY MAKE WINDS VARIABLE...HOWEVER TREND WILL BE FOR SOUTHEAST
WINDS TONIGHT...BECOMING NORTHWEST MONDAY AT UNDER 10 MPH. SOME
MVFR VSBYS WITH FOG FOR A FEW HOURS MONDAY MORNING WITH DEWPOINTS
IN THE LOWER 60S AND LIGHT WINDS.

&&

.PREV DISCUSSION... /ISSUED 315 PM CDT SUN JUN 16 2013/

SHORT TERM...TONIGHT THROUGH WEDNESDAY

WHILE THUNDERSTORMS HAVE BEEN FESTERING THROUGH THE DAY FROM
SOUTHWEST SD TO NORTH CENTRAL NEB...QUIET WEATHER IS IN PLACE
ACROSS THE AREA TODAY. SUBJECTIVE 12Z UPPER AIR ANALYSIS INDICATES
NEARLY ZONAL FLOW ACROSS THE CENTRAL US...WITH WEAK RIDGING ACROSS
THE HIGH PLAINS AND DEEPENING TROUGH OVER THE GREAT LAKES. UPPER-
LEVEL JET EXTENDED FROM CENTRAL NEB ACROSS THE GREAT LAKES AND
TOWARD NEW ENGLAND. 850MB MOISTURE WAS WELL ENTRENCHED ACROSS THE
PLAINS...WITH 850MB DEWPOINTS OF 8C+ INTO SD/NORTHERN IA...AND A
LARGE SWATH OF 16C+ DEWPOINTS IN TX/OK AND OVER WESTERN NEB. AT
THE SURFACE...19Z ANALYSIS INDICATED RIDGING FROM EASTERN SD
THROUGH THE MO RIVER VALLEY..WITH MUCH LOWER SURFACE DEWPOINTS IN
THE 30S/40S TO THE NORTH OF THE RIDGE AXIS. ACROSS THE
CWA..DEWPOINTS RANGED FROM AROUND 50 NORTHEAST TO AROUND 70 IN THE
FAR SOUTH...WITH WEAK EASTERLY WINDS.

MAIN FORECAST CONCERNS ARE POTENTIAL FOR STORMS THIS
EVENING...ANOTHER SLIGHT CHANCE AGAIN TOMORROW AFTERNOON...AND THE
BEGINNING OF A MORE ACTIVE PERIOD ON WEDNESDAY.  SHORT-TERM MODELS
CONTINUE TO SHOW A WIDE RANGE OF SOLUTIONS REGARDING STORMS
TONIGHT...WITH THE MOST AGGRESSIVE RUNS MOVING A LINE OF STORMS
THROUGH CENTRAL TO EASTERN NEB THIS EVENING...WHILE SOME MODELS KEEP
THE CWA ESSENTIALLY DRY TONIGHT.  NORTHEASTERN CWA REMAINS
STABLE...WITH FALLING SURFACE DEWPOINTS...AND HAVE KEPT THE EASTERN
HALF OF THE CWA DRY THROUGHOUT.  DID KEEP A STRIPE OF CHANCE POPS ON
THE WESTERN FRINGE OF THE CWA THIS EVENING...BUT CONFIDENCE IS QUITE
LOW IN STORMS MAKING IT INTO THE AREA.  IN THE SOUTHWEST
CWA...INSTABILITY IS HIGHER...WITH MLCAPE UP TO AROUND 2000-2500
J/KG PER RAPV2 MESOANALYSIS...AND STORMS MAY HAVE A SHOT TO PULSE UP
AND BECOME STRONG/SEVERE.  BULK OF THE SEVERE WEATHER THREAT SHOULD
REMAIN WEST THOUGH...CLOSER TO THE MAIN INSTABILITY AXIS.  ANY
STORMS SHOULD MOVE OUT OF THE AREA BY AROUND MIDNIGHT.

FAIR WEATHER SHOULD CONTINUE THROUGH THE MORNING...WITH AGAIN
CONSIDERABLE UNCERTAINTY IN THE FORECAST FOR MONDAY.  NAM12/GFS
BRING A SURFACE BOUNDARY INTO SOUTHERN NEB BY AFTERNOON...WITH
CONVECTION DEVELOPING ALONG THE BOUNDARY FROM AROUND I-80
SOUTHWARD...AND 4KM WRF ALSO HINTS AT A FEW STORMS IN THE AREA.
HAVE INCLUDED SCHC POPS FROM I-80 SOUTHWARD IN THE AFTERNOON...WITH
LOW CONFIDENCE ON COVERAGE.  SREF INDICATES WEAK DEEP-LAYER
SHEAR...WHICH WOULD LIMIT SEVERE POTENTIAL.  FAIR WEATHER RETURNS
MONDAY NIGHT THROUGH TUESDAY NIGHT AS HIGH PRESSURE PIVOTS OVER
IA...WITH SURFACE WINDS BECOMING SOUTHEASTERLY AND WITH RISING
HEIGHTS AS AN UPPER-LEVEL RIDGE MAKES PROGRESS ONTO THE PLAINS.
WHILE A TROUGH WILL DIG INTO THE ROCKIES...COMBINING WITH UPSLOPE
FLOW TO GENERATE STORMS ON THE HIGH PLAINS...DO BELIEVE THAT STORMS
THAT DEVELOP TUESDAY AFTERNOON/EVENING WILL DIE BEFORE THEY REACH
EASTERN NEB...AND HAVE MAINTAINED A DRY FORECAST.

SIMILAR BUT STRONGER SYNOPTIC SETUP WILL BE IN PLACE ON WEDNESDAY AS
UPPER-LEVEL TROUGH NUDGES OUT OF THE ROCKIES...WITH SOUTHERLY 850MB
WINDS AND SOUTHEASTERLY SURFACE WINDS.  ONCE AGAIN...EXPECT
CONVECTION TO FIRE ON THE HIGH PLAINS...BUT DID INCLUDE A SLIGHT
CHANCE POP ON WEDNESDAY AFTERNOON IN THE WESTERN CWA FOR THE LOW
PROBABILITY THAT CONVECTION COULD DEVELOP INTO CENTRAL NEB AND MOVE
INTO THE AREA BEFORE 00Z.  OVERALL...EXPECT THE RISK OF
THUNDERSTORMS TO MAINLY FOCUS ON WEDNESDAY EVENING/NIGHT.

MAYES

LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY

A FAIRLY ACTIVE AND WARM PERIOD APPEARS TO BE IN STORE FOR THE
EXTENDED PERIOD OF THE FORECAST. TROUGHING IN THE WESTERN US WILL
DOMINATE THE PERIOD AND LEAD TO PERIODIC CHANCES FOR SHOWERS AND
THUNDERSTORMS. THE CLIMATOLOGICAL FAVORED TIMING FOR THIS TIME OF
YEAR IS DURING THE LATE EVENING AND OVERNIGHT HOURS...AND WE WILL
CENTER THE HIGHEST POPS DURING THESE PERIODS BUT TIMING OF
CONVECTION AT THIS RANGE IS VERY DIFFICULT. WILL ALSO PUT THE
HIGHEST POPS IN THE NRN CWA AS THERE IS STRONGER ENSEMBLE SUPPORT
FOR THE SURFACE BOUNDARY TO BE IN THIS AREA. TEMPERATURES WILL
ALSO BE DEPENDENT ON CONVECTIVE DEBRIS AND POTENTIAL OUTFLOW...BUT
MODELS ARE IN GOOD AGREEMENT THAT 850 MB TEMPERATURES WILL WARM
INTO THE LOWER TO MID 20S BY LATE IN THE PERIOD THIS WILL
GENERALLY SUPPORT HIGHS AROUND OR SLIGHTLY WARMER THAN 90 IN PARTS
OF THE AREA.

BOUSTEAD

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&

$$

ZAPOTOCNY