Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 261221 AAB
AFDLBF

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE NORTH PLATTE NE
721 AM CDT TUE APR 26 2016

.UPDATE...
ISSUED AT 719 AM CDT TUE APR 26 2016

THE RAP MODEL IS TRENDING COLDER. THE COLD AIR IS OVER-TAKING THE
FCST AREA AND SNOW IS UNDERWAY ACROSS NORTHWEST NEB IN SOUIX
COUNTY. SNOW MAY BE UNDERWAY IN PARTS OF SHERIDAN COUNTY ALSO. A
NEW FORECAST IS OUT FOR PERIODS OF SNOW AND COOLER TEMPERATURES
TODAY.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 325 AM CDT TUE APR 26 2016

TODAY AND TONIGHT...THE SFC FRONT NEAR DODGE CITY AT 06Z LIFTS NORTH
TO NEAR THE KANSAS NEBRASKA BORDER BY 12Z AND REMAINS STATIONARY
TODAY. THE FRONT THEN GETS SWEPT EAST AND SOUTH TONIGHT AS SFC LOW
PRESSURE DEEPENS ACROSS NCNTL KS.

THE RAP MODEL SHOWS 2000 J/KG OF ELEVATED INSTABILITY JUST NORTH OF
THE SFC FRONT AT 12Z WHICH LIFTS NORTH THROUGH THE FCST AREA TODAY.
THIS INSTABILITY SHOULD BE THE CATALYST FOR THUNDERSTORMS CONTAINING
LARGE AND SMALL HAIL. THIS STORM ACTIVITY COULD BE UNDERWAY BY 12Z
ACROSS SWRN NEB. A SECOND AREA OF ELEVATED INSTABILITY SHOULD REFORM
ACROSS SWRN NEB AROUND 21Z WHICH WILL BE THE GENESIS FOR A SECOND
ROUND OF THUNDERSTORMS TONIGHT WHICH SHOULD LAST FOR MANY HOURS
ACROSS THE SANDHILLS AND PRODUCE AN AREAL AVERAGE RAINFALL NEAR 1
INCH. THE THREAT OF HAIL...LARGE AND SMALL...SHOULD CONTINUE
THROUGHOUT THE EVENING.

THE LATEST RAP MODEL PRODUCES HIGHS ONLY IN THE 40S AND 5OS TODAY.
THIS SEVERAL DEGREES COOLER THAN THE DETERMINISTIC MODEL CONSENSUS.
LOWS TONIGHT FALL INTO THE 30S AND 40S. THE NAM SUGGESTS A MIX OF
RAIN AND SNOW ACROSS SHERIDAN COUNTY WHILE THE GFS KEEPS THE PTYPE
ALL RAIN. THE GFS WAS PREFERRED AS THE SNOW AND COLDER AIR APPEARS
ELUSIVE THIS MORNING...CONFINED TO WY...ND AND MT.

THE TORNADO POTENTIAL APPEARS VERY CONDITIONAL THIS AFTERNOON AS THE
MODEL CONSENSUS LIFTS THE SFC LOW AND TRIPLE PT THROUGH KS TODAY AND
TO NEAR LINCOLN NEB BY WEDNESDAY MORNING. THIS WOULD PROBABLY KEEP
ERN LINCOLN COUNTY...FRONTIER AND SRN CUSTER COUNTIES IN THE COOL
SECTOR LESSENING THE RISK OF TORNADO DEVELOPMENT. IF THE WARM FRONT
CAN LIFT INTO SRN NEB...TO NEAR I-80 EAST OF NORTH PLATTE...THEN THE
TORNADO RISK WOULD INCREASE SIGNIFICANTLY.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 325 AM CDT TUE APR 26 2016

BEGINNING 12Z WEDNESDAY.  THE NEGATIVELY TILTED UPPER LEVEL LOW IS
PROJECTED TO BE CENTERED NEAR THE KS/NEB BORDER ON WEDNESDAY.  THE
PLACEMENT OF THE LOW FAVORS THE HIGHEST POPS ACROSS OUR NORTHERN
ZONES...BUT ALL AREAS HAVE A SHOT AT ADDITIONAL ROUNDS OF
SHOWERS/STORMS.  THE LATEST GUIDANCE HAS BACKED OFF ON THE
INSTABILITY PARAMETERS THIS EVENING FOR WEDNESDAY...BUT SUFFICIENT
ELEVATED CAPE REMAINS FOR AT LEAST AN ISO MENTION OF THUNDER FROM
SOUTHWEST NEB NORTHEAST TO OUR NORTH CENTRAL NEB ZONES.  AS THE LOW
EJECTS EAST IN THE EVENING HOURS...THE MODELS SUGGEST ENOUGH COLD AIR
ON THE BACKSIDE OF THE LOW FOR A COMPLETE CHANGE OVER TO SNOW ACROSS
NW NEB...AND A MIX AS FAR EAST AS THE HIGHWAY 83 CORRIDOR.  THE
RECENT TREND OF THE MODELS HAS BEEN COOLER...WHICH WILL NEED TO BE
MONITORED IN THE EVENT THAT ACCUMULATIONS OCCUR.  WARM GROUND
TEMPERATURES WILL CREATE AN UNFAVORABLE ENVIRONMENT FOR
ACCUMULATIONS ACROSS NW NEB...SO FOR NOW...WILL KEEP ACCUMULATIONS
MINIMAL.  THE LOW WILL LIFT TOWARD SOUTHERN WISCONSIN ON THURSDAY
ALLOWING A LOW AMPLITUDE RIDGE TO FOLLOW.  THE RIDGE WILL BE
CHARACTERIZED AS TRANSIENT AS THE NEXT LOW CLOSES ON THE PLAINS FOR
FRIDAY.  TEMPERATURES WITH THE RIDGE WILL HAVE LITTLE TIME TO
RECOVER...SO THE BELOW AVERAGE HIGHS WILL CONTINUE INTO THE NEXT
SYSTEM WITH THE POSSIBILITY OF A MIX OF SNOW ONCE AGAIN ACROSS
NORTHWEST NEBRASKA EARLY FRIDAY MORNING...ELSEWHERE SHOWERS OF RAIN
ARE FORECAST.  ONE WOULD EXPECT THE TRACK OF THE H5 LOW WOULD ALLOW
SOME INSTABILITY TO WORK BACK INTO SOUTHERN PORTIONS OF THE CWA AT A
MINIMUM.  WILL ONCE AGAIN KEEP AN ISO T MENTION GOING IN THE
FORECAST FRIDAY AFTERNOON INTO EARLY SATURDAY.  IT SHOULD BE NOTED
THAT THE ECMWF IS COOLER THAN THE GFS WITH THE WEEKEND SYSTEM...THUS
A MIX OF SNOW IS POSSIBLE ONCE AGAIN ACROSS NW NEBRASKA DURING THE
EARLY MORNING HOURS AS THE ECMWF SUGGESTS H85 T/S FALLING BELOW 0C.
ANOTHER POTENTIALLY SIGNIFICANT TREND IS THAT BOTH THE GFS AND EC
ARE GENERATING MODERATE QPF AT TIMES OVER MUCH OF THE CWA AS THE
TRACK NOW FAVORS THE SANDHILLS.  IN ADDITION...AS THE H5 LOW TAKES
ON A NEGATIVE TILT OVER THE HIGH PLAINS...IT STALLS AND IMPACTS THE
CWA FOR A PERIOD OF 48 HOURS OR MORE.  SOLID RAIN CHANCES WILL
CONTINUE INTO MONDAY OF NEXT WEEK WITH THE POSSIBILITY OF A MIX OF
RAIN AND SNOW ACROSS THE NORTHWEST DURING THE EARLY MORNING HOURS.
TEMPERATURES WILL BE COOL THROUGH MUCH OF THE EXTENDED GIVEN THE
PRESENCE OF CLOUDS...PRECIP AND PERIODS OF CAA. BY EARLY NEXT WEEK A
WELL DEFINED RIDGE IS SHOWN TO DEVELOP AND SPREAD WARMING TEMPS BACK
ACROSS THE CWA.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 623 AM CDT TUE APR 26 2016

MIXED FLIGHT CONDITIONS MVFR/IFR ARE EXPECTED TO CONTINUE TODAY
AND TONIGHT WITH TSTMS/STRONG/SVR TSTMS. HAIL IS THE SEVERE
WEATHER CONCERN. ONCE LOW LEVEL WINDS BECOME NORTHWEST LATE
TONIGHT...CIGS SHOULD LIFT TO MVFR/VFR IN RAIN.


&&

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

$$

UPDATE...CDC
SHORT TERM...CDC
LONG TERM...JACOBS
AVIATION...CDC


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