000
FXUS63 KLBF 152328
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
628 PM CDT WED MAY 15 2013

.SYNOPSIS...
ISSUED AT 321 PM CDT WED MAY 15 2013

THE H5 ANALYSIS FROM THIS MORNING HAS LOW AMPLITUDE FLOW
ACROSS THE NRN CONUS WITH A SHORTWAVE TROUGH ACROSS QUEBEC AND NEW
ENGLAND. SEVERAL EMBEDDED SHORTWAVES WERE NOTED ACROSS THE SRN THIRD
OF THE CONUS...ONE OVER WEST TX...A SECOND IN THE VICINITY OF THE
FOUR CORNERS AND A THIRD OVER SRN NEVADA. AT THE SURFACE...LOW
PRESSURE WAS CENTERED OVER FAR SWRN KS...WITH A WARM FRONT EXTENDING
ENE OF THIS FEATURE INTO FAR NERN KS. HIGH PRESSURE WAS CENTERED
OVER THE EASTERN BLACK HILLS. BETWEEN THE TWO SURFACE
SYSTEMS...DECENT EASTERLY WINDS HAVE DEVELOPED THIS AFTERNOON WITH
SPEEDS RANGING FROM 15 TO 25 MPH. TEMPERATURES AS OF 2 PM CDT WERE
IN THE UPPER 70S ACROSS ALL OF WESTERN AND NORTH CENTRAL NEBRASKA.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 321 PM CDT WED MAY 15 2013

THROUGH 00Z FRIDAY.  PRECIPITATION CHANCES HEADLINE
THE SHORT TERM DISCUSSION.  CONVECTION ASSOCIATED WITH A WESTERN
CONUS SHORTWAVE TROUGH WILL DEVELOP AND SPREAD EAST INTO THE
NEBRASKA PANHANDLE LATE THIS EVENING...THEN CONTINUE EAST INTO THE
SANDHILLS REGION OVERNIGHT.  COVERAGE WILL INITIALLY BE ISOLATED TO
SCATTERED...HOWEVER INTO TOMORROW STORMS SHOULD BECOME MORE
WIDESPREAD.  THE GFS IS GENERALLY MORE WIDESPREAD WITH ACCUMULATING
QPF...WHEREAS THE NAM SOLUTION CONTINUES TO FAVOR NORTH CENTRAL
NEBRASKA AND PORTIONS OF THE SANDHILLS REGION.  LOWER TROPOSPHERIC
MOISTURE WILL BE ON THE INCREASE THROUGH THE PERIOD...WITH PWATS
INCREASING TO OR IN SOME CASES ABOVE 1.25" BY 15Z THURSDAY.  FEEL
THAT WITH THE INCREASING MOISTURE...LOW LEVEL CONVERGENCE AND MID LEVEL
ENERGY...PRECIPITATION CHANCES WILL BECOME A BIT MORE
WIDESPREAD...THUS WILL MAINTAIN SOLID CHANCE POPS ACROSS MUCH OF THE
REGION THROUGHOUT THE DAY ON THURSDAY.  INSTABILITY WILL BE IN PLACE
AS WELL...WITH SB CAPES RISING AOA 1.5-2.0 KJ/KG BY
MID-AFTERNOON...DEEP CONVECTION THAT DEVELOPS WOULD HAVE THE
CAPABILITY TO PRODUCE LARGE HAIL AND STRONG WIND GUSTS.  ALSO WITH
THE INCREASING LOW LEVEL ATMOSPHERIC MOISTURE...BENEFICIAL RAIN MAY
BE REALIZED UNDER THE HEAVIEST OF CELLS...BUT TOTAL OVERALL QPF
AMOUNTS LOOK TO REMAIN LIGHT /0.25" - 0.50"/ EXCEPT UNDER THE
HEAVIEST OF CELLS.

WITH THE EXPECTED INCREASE IN CLOUDS AND PRECIPITATION...HIGH
TEMPERATURES ARE GOING TO BE TRICKY TOMORROW AFTERNOON ESPECIALLY
SINCE PLENTIFUL WARM AIR ADVECTION WILL BE ON-GOING IN THE LOWER
LEVELS.  WILL CONTINUE TO SIDE TOWARD THE COOLER SIDE OF
GUIDANCE...AND MAINTAIN UPPER 70S TO LOW 80S ACROSS THE FORECAST
AREA...BUT IF THE SUN BREAKS OUT UNDER CLEARING SKIES...THE
INCREASING WARM AIR MAY ALLOW FOR HIGHS WELL INTO THE 80S.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 321 PM CDT WED MAY 15 2013

MID TERM...THURSDAY NIGHT THROUGH SATURDAY NIGHT...MAIN FORECASTING
CHALLENGES ARE PRECIPITATION CHANCES...MAINLY FRIDAY NIGHT THROUGH
SATURDAY...AS WELL AS CLOUDS AND TEMPERATURES. FOR THURSDAY
NIGHT...THE UPPER AIR PATTERN WILL BEGIN TO AMPLIFY ACROSS THE
WESTERN CONUS. SRLY WINDS AND A LOW LEVEL JET WILL DEVELOP THURSDAY
NIGHT...PUSHING LOW LEVEL MOISTURE INTO THE FORECAST AREA OVERNIGHT.
DECIDED TO INCREASE CLOUDINESS LATE THURSDAY NIGHT INTO FRIDAY...AS
BOTH THE GFS AND NAM SOLNS ARE INDICATING DECENT STRATUS POTENTIAL.
WITH SRLY WINDS PERSISTING INTO THE DAY ON FRIDAY...AND THE ABSENCE
OF HIGH LEVEL CLOUDINESS...STRATUS SHOULD SCATTER OUT BY AFTERNOON
ALLOWING TEMPS TO SURGE INTO THE 80S. BY FRIDAY AFTERNOON...LEE SIDE
TROUGHING WILL ALLOW SRLY WINDS TO CONTINUE...AND WILL HELP TO
ESTABLISH A DRY LINE ACROSS WESTERN KS AND NEBRASKA FRIDAY
AFTERNOON. VERY UNSTABLE CONDS WILL DEVELOP FRIDAY AFTERNOON AND
EVENING ACROSS THE WESTERN CWA...WITH CAPES RANGING FROM 2500 TO
3500 J/KG. WITH A WEAKENING CAP PRESENT IN THE PANHANDLE AND NWRN
ZONES...CHANCES FOR THUNDERSTORM INITIATION LOOKS DECENT. FURTHER
SOUTH IN THE SWRN CWA AND WESTERN KS...A DECENT CAPPING INVERSION
EXISTS...SO WILL CONFINE POPS TO THE NORTHWEST AND PANHANDLE ZONES
FRIDAY AFTERNOON. DEEP LAYER SHEAR CONTINUES TO BE MEAGER FRIDAY
AFTERNOON/FRIDAY EVENING...SO WIDESPREAD SEVERE STORMS DOESN/T LOOK
PROBABLE ATTM. WITH RESPECT TO PCPN CHANCES FRIDAY NIGHT...HAVE LEFT
IN A MENTION OF THEM IN THE CENTRAL AND EAST...THOUGH CONFIDENCE IN
THEM IS WEAK AT BEST. THE LATEST NAM HAS THE LOW LEVEL JET FRIDAY
NIGHT FOCUSED ACROSS WESTERN NEBRASKA...WHILE THE GFS IS FURTHER
EAST AND OVER MY CENTRAL AND EASTERN CWA OVERNIGHT. GIVEN THE DEGREE
OF INSTABILITY AND SOME DOUBT AS TO WHERE THE LLJET WILL FOCUS
ITSELF...WILL CONTINUE LOW POPS IN THE CENTRAL AND EAST OVERNIGHT
FRIDAY NIGHT.

ON SATURDAY...THE INGREDIENTS FOR MORE WIDESPREAD SEVERE
THUNDERSTORMS ARE EVIDENT ACROSS WESTERN AND NORTH CENTRAL NEBRASKA.
THE LATEST SWODY48 HAS MOST OF OUR AREA OUTLOOKED FOR SEVERE STORMS
SATURDAY AND SATURDAY NIGHT...GENERALLY EAST OF HIGHWAY 61 FROM
MERRIMAN TO IMPERIAL. ALOFT...THE UPPER LEVEL TROUGH OF LOW PRESSURE
MENTIONED ABOVE...WILL CROSS THE INTERMOUNTAIN WEST SATURDAY...WITH
A STRONG UPPER LEVEL SHORTWAVE EMERGING ONTO THE HIGH PLAINS OF
EASTERN COLORADO SATURDAY AFTERNOON. A WELL ESTABLISHED DRY LINE
WILL EXTEND FROM THE NEBRASKA PANHANDLE INTO NERN COLORADO AND WRN
KS SATURDAY AFTERNOON. BOTH THE NAM AND GFS ARE INDICATING A
WEAKENING CAP...IN PARTICULAR ACROSS WESTERN KS AND NERN COLORADO
LATE SATURDAY AFTERNOON...WHICH IS COLLOCATED WITH A DRY LINE BULGE
OVER NERN COLORADO AND WRN KS. WITH H5 WINDS ORIENTED SSW TO NNE AND
WITH INITIATION EXPECTED IN NERN COLORADO AND NWRN KS...CHANCES FOR
PRECIPITATION WILL INCREASE SUBSTANTIALLY FOR WESTERN AND NORTH
CENTRAL NEBRASKA LATE SATURDAY AFTERNOON INTO SATURDAY EVENING.
CONVECTION WILL BE ENHANCED INTO THE OVERNIGHT HOURS THANKS TO A
STRONG LOW LEVEL JET FOCUSED OVER CENTRAL AND EASTERN NEBRASKA. THE
ONGOING FCST HAS THIS HANDLED NICELY WITH 40 POPS IN THE WEST AND 50
TO 60 POPS IN THE EAST. AS FOR THE SEVERE THREAT SATURDAY
AFTERNOON...LARGE HAIL AND DAMAGING WINDS APPEAR TO BE THE MAIN
THREATS ATTM...AS VERY  STEEP MID LEVEL LAPSE RATES ARE EXPECTED AND
WET BULB ZERO HTS ARE IN THE VERY FAVORABLE RANGE OF 8000 TO 10000
FT AGL. THE THREAT FOR HAIL AND WINDS WILL CONTINUE INTO THE
OVERNIGHT...WITH THE THREAT FOR TORNADOES INCREASING INTO THE MID
EVENING HOURS AS THE MODELS ARE INDICATING BACKING OF THE LOW LEVEL
WINDS...ESPECIALLY OVER SWRN NEBRASKA.

SUNDAY THROUGH WEDNESDAY...THE MAIN UPPER LEVEL TROUGH OF LOW
PRESSURE WILL EMERGE ONTO THE CENTRAL PLAINS SUNDAY AFTERNOON.
SHOWERS AND THUNDERSTORMS ARE EXPECTED ONCE AGAIN AND MAY BE STRONG
TO POSSIBLY SEVERE IN SOME EASTERN PORTIONS OF THE CWA. ATTM...THE
DAY 5 OUTLOOK FROM SPC HAS THE THREAT FOR SEVERE STORMS EAST OF THE
AREA...BUT WITH THE SYSTEM SLOWING SOMEWHAT...THE THREAT IS EXPECTED
TO SHIFT WEST. SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO
MONDAY...ENDING MONDAY NIGHT INTO TUESDAY AS THE UPPER LEVEL LOW
TRACKS INTO THE UPPER MIDWEST. TRANQUIL AND DRY CONDS WILL SET IN
MONDAY NIGHT...PERSISTING INTO WEDNESDAY AS BROAD NWRLY FLOW ALOFT
DEVELOPS ACROSS THE REGION...WITH RELATIVELY DRY BL CONDITIONS
PRESENT.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 627 PM CDT WED MAY 15 2013

THERE IS CONSIDERABLE DISAGREEMENT AMONG THE DIFFERENT SHORT RANGE
SIMULATIONS REGARDING THE POTENTIAL AND TIMING FOR THUNDERSTORMS
THROUGH THE NEXT 36 HOURS. THERE IS A WEAK SURFACE FRONT ACROSS
NORTHERN AND WESTERN KANSAS WHICH COULD PROVIDE A FOCUS FOR
THUNDERSTORM DEVELOPMENT TONIGHT. HOWEVER...SHORT RANGE PROJECTIONS
INDICATE THE HIGHEST CHANCES OF THUNDERSTORMS 15Z OR LATER WHEN THE
FRONT BEGINS TO MAKE ITS WAY NORTHWARD INTO NEBRASKA. GOING WITH THE
MOST LIKELY SCENARIO...WE WILL BRING SHOWERS AND THUNDERSTORMS INTO
CENTRAL AND WSETERN NEBRASKA AFTER 15Z. THIS TIMING WOULD APPLY TO
THE AREA EAST OF AN IEN-OGA LINE. ALONG AND WEST OF THAT LINE...AN
EARLIER ONSET IS POSSIBLE.

&&

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

$$

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