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000
FXUS63 KLBF 181816
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
116 PM CDT SAT MAY 18 2013

.MESOSCALE DISCUSSION...
ISSUED AT 1251 PM CDT SAT MAY 18 2013

SEVERE THUNDERSTORM POTENTIAL STILL ON TRACK THIS AFTERNOON AND
EVENING. LATEST SFC ANALYSIS HAS A SFC LOW PRESSURE CENTER LOCATED
IN EASTERN COLORADO...WITH A DRY LINE EXTENDING SOUTH FROM THE
LOW CENTER THROUGH THE TX PANHANDLE AND WARM FRONT EAST NORTHEAST
ACROSS NORTHERN KS. SFC LOW SHOULD CONTINUE TO LIFT SLOWLY
NORTHWARD TO NEAR GOODLAND BY LATE AFTERNOON A WARM FRONT WILL
ARC NORTHEAST INTO SOUTHWEST NEBRASKA FROM THE LOW CENTER.
THUNDERSTORMS SHOULD INITIATE AROUND IMPERIAL AND HAYES CENTER
AROUND 400 PM CDT ON THE NOSE OF VERY STEEP LOW LEVEL LAPSE
RATES/DRY LINE WHICH WILL BE PUNCHING INTO FAR SOUTHWEST NEBRASKA.
STORMS LIKELY TO BECOME SUPERCELLS QUICKLY AS THEY MOVE NORTHEAST
INTO A VERY TO EXTREMELY UNSTABLE AND FAVORABLE SHEARED
ATMOSPHERE. BACKED SFC WINDS TO THE SOUTHEAST ARE EXPECTED ACROSS
MOST OF SOUTHWEST NEBRASKA...WITH SPEEDS INCREASING JUST OFF THE
SFC EARLY THIS EVENING. THE TIME FRAME FROM 600 PM CDT TO 900 PM
CDT LOOKS TO BE THE MOST FAVORABLE FOR TORNADO DEVELOPMENT ACROSS
SOUTHWEST NEBRASKA. IN ADDITION TO THE TORNADO THREAT...VERY LARGE
HAIL...POSSIBLE BASEBALL SIZE OR LARGER...IS EXPECTED. STORMS WILL
LIKELY MERGE EARLY THIS EVENING INTO A COMPLEX AS THEY ADVANCE
NORTHEAST TOWARD CENTRAL AND NORTH CENTRAL NEBRASKA. LARGE HAIL
AND DAMAGING WINDS WILL BE THE MAIN THREATS FROM THE COMPLEX.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 305 AM CDT SAT MAY 18 2013

THE RAP13 SEEMS TO HAVE THE BEST HANDLE ON THE STRATUS LIFTING NORTH
INTO THE FCST AREA THIS MORNING. IT WAS ALSO THE PREFERRED MODEL FOR
THE SEVERE WEATHER EVENT EXPECTED TO UNFOLD LATE THIS AFTERNOON AND
TONIGHT. THE STRATUS SHOULD BUILD THROUGH THE FCST AREA ALONG AND
WEST OF HIGHWAY 83 THIS AM AND THEN MIX OUT LATE MORNING/EARLY
AFTERNOON.

THE ONGOING TSTMS AND ISOLD SEVERE STORMS SHOULD CONTINUE TO LIFT
NORTH AND EXIT THE FCST AREA BY SUNRISE. THEREAFTER THE RUC PUSHES
MOISTURE AND INSTABILITY FARTHER WEST THAN THE NAM AND SHARPENS UP
THE DRY LINE ACROSS WRN NEB THIS AFTERNOON. ALL THE WHILE
MAINTAINING A STRONG CAP WHICH SHOULD BREAK AROUND 22Z ON THE
DRYLINE. SPC PROVIDED USEFUL INSIGHT INTO THE EVOLUTION OF THIS
EVENT SUGGESTING LARGE/VERY LARGE HAIL AND WIND DAMAGE LATE THIS
AFTERNOON ALONG THE DRY LINE. THE CONVECTIVE COMPLEX MOVES EAST
TOWARD HIGHWAY 83 THIS EVENING. AT THE SAME TIME...LOW LEVEL WINDS
ARE EXPECTED TO BACK AND INCREASE IN SPEED TOWARD SUNSET OR SHORTLY
THEREAFTER ENHANCING THE TORNADO THREAT FOR A FEW HOURS...ROUGHLY
01Z-04Z.

THE ENTIRE SYSTEM OF STORMS WILL CONTINUE TO MOVE NORTHEAST
OVERNIGHT AND EXIT THE FCST AREA BY SUNDAY MORNING.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 305 AM CDT SAT MAY 18 2013

THE MODELS ARE IN RELATIVELY GOOD AGREEMENT REGARDING UPPER
TROUGH APPROACHING THE REGION ON SUNDAY. THE GFS AND ECMWF BOTH
HAVE THE TROUGH CLOSING OFF AND WRAPPING UP OVER SIOUX FALLS AREA
MONDAY THROUGH WEDNESDAY. THIS WILL MEAN COOLER CONDITIONS AND A
BROAD SCALE AREA OF PRECIPITATION POTENTIALLY ON THE BACK SIDE OF
THE LOW. LOOKING CLOSER AT SUNDAY...SEVERE THUNDERSTORMS WILL BE
POSSIBLE DURING THE AFTERNOON IN THE FAR EASTERN FORECAST AREA IN
VICINITY OF THE COLD FRONT ASSOCIATED WITH THE APPROACHING SYSTEM.
ON MONDAY AND TUESDAY...MODELS ARE INDICATING MOISTURE-RICH AIR
WRAPPING AROUND THE LOW PRESSURE SYSTEM INTO PARTS OF CENTRAL AND
WESTERN NEBRASKA. IT APPEARS THAT THE BEST CHANCE FOR
PRECIPITATION WITH THIS SYSTEM WILL BE IN NORTH-CENTRAL NEBRASKA.
HIGHS WILL DIP INTO THE MID 50S TO MID 60S ON MONDAY AND
TUESDAY...BEFORE REBOUNDING TO THE MID 60S TO MID 70S THURSDAY AND
FRIDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1251 PM CDT SAT MAY 18 2013

MVFR CONDITIONS WILL CONTINUE TO BE POSSIBLE ACROSS PORTIONS OF
WESTERN AND NORTH CENTRAL NEBRASKA THIS AFTERNOON IN AREAS OF
LOWER STRATUS CLOUDS.

TSTMS...SOME SEVERE...WILL DEVELOP ACROSS SOUTHWEST NEB LATE THIS
AFTERNOON...AND SPREAD NORTHEAST ACROSS THE ENTIRE AREA THROUGH
THE EVENING. WINDS WILL BE SOUTHEAST...BUT VARIABLE AND GUSTY NEAR
ANY STORM.

&&

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

$$

MESOSCALE...TAYLOR
SHORT TERM...CDC
LONG TERM...KNUTSVIG
AVIATION...TAYLOR