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000
FXUS63 KLBF 171118
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
618 AM CDT MON JUN 17 2013

.SYNOPSIS...
ISSUED AT 358 AM CDT MON JUN 17 2013

AT 08Z...SURFACE WIND BETRAYED THE PRESENCE OF A TROUGH ACROSS THE
HIGH PLAINS OF EASTERN WYOMING AND EASTERN COLORADO. THERE WAS ALSO
A FRONT...INDICATED BY DEWPOINTS AND A SLIGHT WIND SHIFT...ACROSS
SOUTHEAST NEBRASKA AND NORTH CENTRAL TO WESTERN
KANSAS.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 358 AM CDT MON JUN 17 2013

WITH A BOUNDARY OR SURFACE FRONT ALONG THE KANSAS-NEBRASKA BORDER...
THERE IS A GOOD FOCUS LINE FOR THUNDERSTORM DEVELOPMENT. WITH
CONVECTIVE POTENTIAL ENERGY AT 2500J/KG IN SOUTH CENTRAL AND
SOUTHWEST NEBRASKA BY LATE MORNING...CONVECTION IS LIKELY TO BE
STRONG THOUGH NOT NECESSARILY SEVERE. THE 0-6KM BULK SHEAR IS
FORECAST TO BE ONLY ABOUT 30KT...WHICH IS NOT EXTREMELY FAVORABLE
FOR SUSTAINED UPDRAFTS. LIKE YESTERDAY THOUGH...IT MAY INITIATE
FAIRLY EARLY ON THE HIGH PLAINS BOUNDARY.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 358 AM CDT MON JUN 17 2013

CONVECTION CHANCES CONTINUE TO HEADLINE THE EXTENDED
PERIODS...WITH A SECONDARY FOCUS BEING WARMING TEMPERATURES LATE
THIS WEEK.

NOT MUCH HAS CHANGED OVER THE PAST 24 HOURS CONCERNING THE SYNOPTIC
TRANSITION OF THE UPPER LEVELS FROM QUASI-ZONAL TO SOUTHWESTERLY.
THE OPERATIONAL MODELS AND ENSEMBLES CONTINUE TO ADVERTISE THE
ESTABLISHMENT OF AN UPPER TROUGH/LOW ACROSS THE PACIFIC
NORTHWEST...WHICH IN TURN WILL FORCE AND AMPLIFY AN UPPER RIDGE EAST
ACROSS THE PLAINS. WITH THE RIDGE AXIS SHIFTING EAST...SOUTHWESTERLY
FLOW ALOFT WILL PREVAIL ACROSS THE HIGH PLAINS OF WESTERN NEBRASKA
AS EARLY AS 06-12Z WEDNESDAY.  THEREAFTER...SOUTHWESTERLY FLOW WILL
REMAIN ENTRENCHED ACROSS THE NORTHERN/CENTRAL PLAINS THROUGH THE
EXTENDED PERIODS AS THE UPPER LOW RELUCTANTLY SHIFTS EAST ACROSS THE
BITTEROOTS AND INTO THE NORTHERN ROCKIES.  WHILE THE LARGE SCALE
DETAILS ARE HANDLED FAIRLY WELL IN THE EXTENDED...THE SMALLER SCALE
PERTURBATIONS CONTINUE TO BE PROBLEMATIC TO THE FORECAST...WITH VERY
LITTLE IN THE WAY OF CONSISTENCY SEEN BETWEEN THE VARIOUS
SOLUTIONS.  TIMING AND LOCATION OF THESE PERTURBATIONS /ASSOCIATED
INCREASED OMEGA/ IS CRUCIAL TO OUR PRECIPITATION FORECAST AND GIVEN
THE LACK OF CONSISTENCY...POP AND ASSOCIATED QPF FORECAST CONFIDENCE
IS RATHER LOW...ESPECIALLY BEYOND 12Z THURSDAY.  FOR THE EXTENDED
PERIODS BEYOND 12Z THURSDAY...MADE LITTLE IN THE WAY OF CHANGE TO
THE ALLBLEND PROCEDURE SAVE FOR LIMITING POP VALUES TO LESS THAN 30
PERCENT.  EVEN THOUGH THE PROBABILITY OF SUCCESSFULLY IMPROVING THE
ALLBLEND FORECAST AT THIS JUNCTURE IS RATHER LOW...I COULDN/T
JUSTIFY LEAVING POPS ABOVE 30 PERCENT THIS FAR OUT...ESPECIALLY
GIVEN THE UNPREDICTABLE NATURE OF THESE SUBTLE PERTURBATIONS.  FOR
THE 12Z TUESDAY THROUGH 12Z THURSDAY TIMEFRAME...THERE IS CERTAINLY
SOME TIMING AND LOCATIONAL DIFFERENCES THAT YET NEED TO BE RESOLVED
WITH THE OPERATIONALS...BUT I GENERALLY FOCUSED THE HIGHEST POPS
ACROSS WESTERN PORTIONS OF THE CWA DURING THE AFTERNOON HOURS AND
THEN CARRIED THOSE POPS EAST THROUGH THE EVENING/OVERNIGHT. AMPLE
INSTABILITY AND STEEP LAPSE RATES COULD ALLOW FOR PERIODIC LARGE
HAIL AND/OR GUSTY ERRATIC WIND.  CONFIDENCE IS LOW
HOWEVER...ESPECIALLY SINCE CONVECTIVE FEEDBACK IN THE OPERATIONALS
IS READILY APPARENT.  FOR NOW WILL LEAVE THE POPS AT 35-40 PERCENT
OR LESS DURING THIS TIME PERIOD.

TEMPERATURE WISE THROUGH THE COMING WORK WEEK...WITH BUILDING
HEIGHTS AND INCREASING SOUTHERLY FLOW ANTICIPATED...HIGHS WILL BEGIN
TO SLOWLY MODERATE WITH WIDESPREAD TEMPERATURES OF THE LOW TO MID
80S EXPECTED TUESDAY AND WEDNESDAY...AND POSSIBLY A RETURN TO THE
LOW 90S FOR SOUTHWEST NEBRASKA THURSDAY AND FRIDAY.  LOWS WILL
REMAIN SEASONAL TO SLIGHTLY ABOVE AVERAGE AND GREATLY DEPENDENT ON
ANY NOCTURNAL CLOUDS/PRECIPITATION.  FOR NOW...WILL KEEP LOWS MAINLY
IN THE 60S THROUGHOUT THE EXTENDED PERIODS.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 618 AM CDT MON JUN 17 2013

SOME PATCHY VALLEY FOG IN THE LBF AREA WILL DISSOLVE FAIRLY QUICKLY
THIS MORNING AFTER SUNRISE. THEN...NO WEATHER RESTRICTIONS ARE EXPECTED
EXCEPT NEAR THUNDERSTORMS.

THUNDERSTORMS IN SOUTHWEST SOUTH DAKOTA AND EAST CENTRAL WYOMING WILL
MOVE ACROSS THE NORTHERN NEBRASKA PANHANDLE AND EVENTUALLY EXPAND INTO
A THUNDERSTORM SYSTEM LATE THIS MORNING AS THEY MOVE EAST. THE LATEST
RAPID REFRESH SHORT RANGE PROJECTION SHOWS STORMS MOVING INTO THE VTN
AREA AROUND 17Z AND INTO THE LBF AREA AROUND 19Z.

THERE ARE HINTS OF ANOTHER THUNDERSTORM SYSTEM THIS EVENING AFTER
00Z...BUT THE UNCERTAINTY IS HIGH.

&&

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

$$

SYNOPSIS...SPRINGER
SHORT TERM...SPRINGER
LONG TERM...JACOBS
AVIATION...SPRINGER