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000
FXUS63 KLBF 191139
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
639 AM CDT WED JUN 19 2013

.SYNOPSIS...
ISSUED AT 339 AM CDT WED JUN 19 2013

ANALYSIS OF THE 08Z REGIONAL MSL DATA SHOWED AT LEAST TWO
BOUNDARIES...ONE ACROSS SOUTHEAST TO NORTHWEST SOUTH DAKOTA AND
ANOTHER FROM EAST CENTRAL NEBRASKA THROUGH SOUTH CENTRAL TO
NORTHWEST NEBRASKA. THERE WAS NOT A DISTINCT DEWPOINT CONTRAST
ASSOCIATED WITH THE BOUNDARIES AS THERE WAS YESTERDAY. RADAR
CONTINUED TO SHOW A SLOW MOVING PRECIPITATION SYSTEM OVER THE
WESTERN SANDHILLS. WITH A FEW THUNDERSTORMS IN AND AROUND THE BROAD
PRECIPITATION AREA.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 339 AM CDT WED JUN 19 2013

THE SHORT TERM HIGH RESOLUTION RAPID REFRESH AND THE RAP13 SHOW THE
PRECIPITATION WEAKENING AND DISSIPATING BEFORE IT GETS MUCH PAST
CENTRAL NEBRASKA. HOWEVER...THE ASSOCIATED RAIN-COOLED AIR MAY
PROVIDE A BOUNDARY FOR A FOCUS OF CONVECTIVE DEVELOPMENT. THE
SURFACE TROUGH ACROSS WESTERN NEBRASKA IS ALSO A POTENTIAL FOCUS FOR
CONVECTION. IN FACT...THE NAM12 AND RAP13 BOTH SHOW THE MOST
UNSTABLE CONDITIONS ALONG THAT BOUNDARY WITH SURFACE BASED AVAILABLE
CONVECTIVE ENERGY ON THE ORDER OF 4500J/KG OVER THE SOUTHERN
NEBRASKA PANHANDLE AND THE SOUTHWEST WITH 0-6KM BULK SHEAR OF 40KT
OR HIGHER. HOWEVER...THE NAM12 EXTENDS THOSE CONDITIONS NORTHWARD
WELL INTO WESTERN SOUTH DAKOTA. THEREFORE...CONFIDENCE IS MODERATE
TO HIGH THAT STRONG CONVECTION WILL DEVELOP OVER SOUTHWEST NEBRASKA.
THOUGH CONFIDENCE IS NOT AS HIGH...THERE IS A POSSIBILITY OF STRONG
CONVECTION OVER MUCH OF WESTERN NEBRASKA. DIURNAL MIXING AND
RESULTING DESTABILIZATION OF THE BOUNDARY LAYER WOULD INDICATE
CONVECTIVE INITIATION LATE AFTERNOON. REGARDING THE BOUNDARY FROM
THE CONVECTION EARLY THIS MORNING...THUNDERSTORMS ARE WILL PROBABLY
RE-DEVELOP IN NORTH CENTRAL NEBRASKA LATE MORNING OR EARLY
AFTERNOON. HOWEVER...THERE IS NOT MUCH SUPPORT TO FOR STRONG
CONVECTION.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 339 AM CDT WED JUN 19 2013

LARGE UPPER LEVEL LOW WILL SLOWLY MEANDER EAST INTO THE PACIFIC
NORTHWEST THURSDAY. A LEAD SHORTWAVE WILL EJECT EAST/NORTHEAST
ACROSS THE CENTRAL AND NORTHERN PLAINS...WITH AN ASSOCIATED COLD
FRONT EXPECTED TO EXTEND FROM ONEILL TO NORTH PLATTE BY LATE
AFTERNOON. THIS FRONT WILL MAKE VERY LITTLE PROGRESS EAST OF THIS
LINE AS SURFACE LOW PRESSURE DEEPENS ACROSS SOUTHWEST
NEBRASKA/NORTHWEST KANSAS DURING THE AFTERNOON AND EVENING. SET UP
WOULD APPEAR FAVORABLE FOR SURFACE BASED THUNDERSTORM DEVELOPMENT
ALONG THE FRONT DURING THE AFTERNOON...EXCEPT FOR A FAIRLY STOUT
INVERSION AROUND 700 MB. A GLANCE AT 700 MB TEMPS SHOW A FAIRLY
WARM LAYER AT THAT LEVEL /13 TO 15C/ BUT 500 MB TEMPS ARE /-8 TO
-10C/ AND ACTUALLY COOL A BIT MORE THURSDAY NIGHT. SO THIS
SUGGESTS FAIRLY UNSTABLE CONDITIONS ALOFT. IT DOES APPEAR THE LOW
LEVEL CAP SHOULD NEARLY ERODE...ESPECIALLY ACROSS SOUTHWEST
NEBRASKA DURING THE AFTERNOON...BUT NOT SURE WILL BE ABLE TO
COMPLETELY OVERCOME CAPPING INVERSION AS INDICATED ON
SOUNDINGS...SO WILL CONTINUE A DRY FORECAST DURING THE DAY
THURSDAY. THURSDAY NIGHT...NAM MODEL LOOKS QUITE FAVORABLE FOR
ELEVATED STORMS ALONG AND NORTH OF THE FRONT ACROSS THE SANDHILLS
AND NORTH CENTRAL NEBRASKA...WITH A 50 KT SOUTHERLY LLJ NOSING
NORTH INTO THE BOUNDARY FROM KANSAS. WILL INCREASE POPS A BIT
THURSDAY NIGHT...AS CONTINUED ASCENT FROM THE LLJ APPEARS TO
OVERCOME THE INVERSION AT 700 MB WITH PARCELS ABLE TO ENTER THE
UNSTABLE LAYER JUST ABOVE THE INVERSION.

FRIDAY INTO FRIDAY NIGHT...SIMILAR SYNOPTIC SET UP WHEN COMPARED TO
THURSDAY. LEEWARD LOW WILL REMAIN ANCHORED ACROSS NORTHEAST
COLORADO...WITH A NEARLY STATIONARY FRONT LYING SOUTHWEST TO
NORTHEAST ACROSS THE FORECAST AREA TO THE NORTHEAST OF THE COLORADO
LOW. IN THE UPPER LEVELS...LARGE UPPER LOW WILL REMAIN ANCHORED
ACROSS THE NORTHERN ROCKIES...WITH EMBEDDED DISTURBANCES MARCHING
EAST/NORTHEAST ACROSS THE AREA IN MODEST WEST/SOUTHWEST FLOW ALOFT.
AGAIN THUNDERSTORMS POSSIBLE FRIDAY AND ESPECIALLY FRIDAY NIGHT AS
SOUTHERLY LLJ CRANKS UP ONCE AGAIN ACROSS KANSAS...WITH NOSE OF JET
DIRECTED AT OUR FORECAST AREA. SEVERE THREAT MAT BE A LITTLE HIGHER
THAN ON THURSDAY AS SHEAR APPEARS SOMEWHAT STRONGER.

SIMILAR PATTERN CONTINUES THROUGH THE WEEKEND...WITH A FRONT
REMAINING IN OR VERY NEAR THE AREA.

TEMPERATURE WISE...COULD BECOME A BIT TRICKY AS THE AFOREMENTIONED
FRONT REMAINS IN THE AREA. HIGHS MAY END UP BEING A LITTLE COOLER
THAN FORECASTED ACROSS THE NORTH...AS THAT AREA MAY END UP REMAINING
TO THE NORTH OF THE FRONT FOR MUCH OF THE PERIOD...ESPECIALLY IF
CONVECTION HELPS TO REINFORCE THE FRONT. THE SOUTH DEFINITELY STANDS
THE BEST CHANCE OF BEING THE WARMEST AREA...WITH HIGHS IN THE 90S
LIKELY AT LEAST SOME OF THE TIME. HERE TOO THE FRONT COULD POSSIBLE
SLIP JUST SOUTH OF THE AREA DEPENDING ON CONVECTION. WILL CONTINUE
TO MONITOR.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 638 AM CDT WED JUN 19 2013

FOUR OF FIVE SHORT TERM MODELS SHOW THUNDERSTORMS DEVELOPING ON A
BOUNDARY THIS MORNING ACROSS NORTHERN KANSAS THEN SPREADING INTO
CENTRAL THROUGH SOUTHWEST NEBRASKA. HOWEVER...COVERAGE IS EXPECTED
TO BE LIMITED AND THUNDERSTORMS WILL NOT BE INCLUDED IN THE TERMINAL
FORECASTS FOR LBF AND VTN AT THIS TIME. BY 15Z...INSTABILITY AND
WIND FIELDS SEEM TO SUPPORT THAT SCENARIO. CONDITIONS ARE NOT
EVOLVING YET AS THOSE MODELS INDICATE...CASTING A PALL OF
UNCERTAINTY OVER THE FORECAST.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...SPRINGER
SHORT TERM...SPRINGER
LONG TERM...TAYLOR
AVIATION...SPRINGER