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000
FXUS63 KLBF 222025
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
325 PM CDT WED MAY 22 2013

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 320 PM CDT WED MAY 22 2013

LOW PRESSURE WAS CENTERED OVER SOUTHWEST WISCONSIN AT MID AFTERNOON
WEDNESDAY...WITH HIGH PRESSURE BUILDING INTO THE PLAINS. 850MB
TEMPERATURES AS OBSERVED FROM 22.12Z SOUNDINGS WERE FROM 3-6C ACROSS
THE NORTHERN PLAINS. LOOKING UPSTREAM...RIDGING ALOFT WAS SEEN ON
WATER VAPOR AS A STRONG UPPER LOW HAS MOVED INTO THE PACIFIC
NORTHWEST.

BACKDOOR COLD FRONT MOVES THROUGH THE FORECAST AREA THIS EVENING AS
HIGH PRESSURE IS CENTRALIZED OVER THE NORTHERN PLAINS. FOR
TONIGHT...WITH RETURN FLOW INTO THE WESTERN PART OF THE FORECAST
AREA...COULD SEE MOISTURE ADVECTING IN...AS WELL AS MOISTURE POOLING
AROUND THE FRONT FOR FURTHER DEVELOPMENT OF STRATUS. SO BELIEVE
CLOUDS WILL AGAIN BE ON THE INCREASE ACROSS THE ENTIRE FORECAST
AREA. THIS WILL KEEP TEMPERATURES FROM DROPPING OFF TOO FAR
OVERNIGHT...AND WILL KEEP LOWS IN THE MID 40S...DESPITE SUGGESTIONS
FROM MODEL GUIDANCE TO HAVE LOWS IN THE UPPER 30S AND LOW 40S /WHICH
WOULD BE POSSIBLE IF SKIES CLEAR RATHER THAN STAY CLOUDY DUE TO THE
COOLER THAN NORMAL AIRMASS IN PLACE.

WILL GET RETURN FLOW BEGINNING ON THURSDAY...WITH THE UPPER LEVEL
RIDGE BUILDING IN AT THE MID LEVELS. BUT TEMPERATURES AT 850-700MB
DON/T REALLY START TO WARM UNTIL AFTER 24.00Z SO EXPECTING ANOTHER
COOL DAY ON THURSDAY...EVEN THOUGH SHOULD GET AT LEAST PARTIAL
SUNSHINE ACROSS MUCH OF NEBRASKA. ONGOING FORECAST HAD MID TO UPPER
60S FOR HIGHS AND THIS STILL LOOKS REASONABLE SO ONLY MINOR
ADJUSTMENTS MADE FOR TEMPERATURES.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 320 PM CDT WED MAY 22 2013

THE END OF THE WEEK IS DOMINATED BY TWO UPPER LEVEL LOW PRESSURE
SYSTEMS FIRMLY IN PLACE ALONG THE EASTERN AND WESTERN COASTS...WITH
AN AMPLIFIED RIDGE AXIS RIGHT UP THE PLAINS REGION. THE RIDGE AXIS
WILL SLOWLY SHIFT EAST...PUTTING WESTERN NEBRASKA IN SOUTHWEST FLOW
ALOFT AND A RATHER UNSETTLED WEATHER PATTERN. MODELS ARE IN GOOD
AGREEMENT ON A SHORTWAVE TROUGH EMBEDDED IN THE SOUTHWEST FLOW
MOVING OVER THE CENTRAL PLAINS THURSDAY NIGHT. AN INVERTED LEE SIDE
TROUGH WILL ALLOW FOR SOUTHERLY FLOW TO ADVECT MOISTURE BACK INTO
THE AREA. THIS COMBINATION SHOULD ALLOW FOR A CHANCE OF SHOWERS AND
MAYBE A FEW THUNDERSTORMS THURSDAY NIGHT...MAINLY ALONG THE NOSE OF
THE 20 TO 30 KT LLJ WHICH WILL VEER OFF INTO CENTRAL NE BY THE
MORNING HOURS.

STORM CHANCES WILL CONTINUE FRIDAY INTO FRIDAY NIGHT. STORMS MAY
INITIATE FRIDAY EVENING ACROSS THE EASTERN PANHANDLE AND WESTERN
SANDHILLS AND THEN MOVE NORTHEAST. A FEW STRONG TO SEVERE STORMS
WILL BE POSSIBLE AS SFC CAPE BUILDS TO AOA 1000 J/KG BENEATH 30 KTS
OF DEEP LAYER SHEAR. ONE LIMITING FACTOR WILL BE A STOUT CAP IN
PLACE WHICH COULD KEEP ACTIVITY ISOLATED UNTIL THE LLJ CRANKS UP
OVERNIGHT.

THE SEVERE WEATHER POTENTIAL FOR SATURDAY WILL HAVE TO BE CLOSELY
MONITORED AS MODELS ARE INDICATING A SETUP FAVORABLE FOR MORE ROBUST
SEVERE STORMS...ALTHOUGH A FEW DIFFERENCES IN THE MODELS SUCH AS THE
POSITION OF THE WARM FRONT WILL NEED TO BE IRONED OUT. MODEST
LOW-LEVEL/DEEP LAYER SHEAR PROFILES AND SFC CAPE ON THE ORDER OF
2000-3000 J/KG WILL BE WELL ESTABLISHED OVER WESTERN NE BY THE EARLY
EVENING HOURS. SFC WINDS WILL BACK SOUTHEAST AS ANOTHER SHORTWAVE
TROUGH WILL DEEPEN A SFC LOW OVER NORTHEAST COLORADO. STORMS WOULD
LIKELY CONGEAL INTO A LINEAR SYSTEM AND MOVE EAST SATURDAY NIGHT AS
LLJ STRENGTHENS TO 40+ KTS AND VEERS OFF TO THE EAST.

STORM CHANCES CONTINUE THROUGH THE EXTENDED PERIOD AS THE HIGH
PLAINS REMAINS IN A SOUTHWEST FLOW PATTERN. WEST COAST LOW WILL
CONTINUE TO EJECT SHORTWAVES OVER THE AREA AS THE RIDGE AXIS
CONTINUES TO SHIFT EAST AND THE FLOW BECOMES LESS AMPLIFIED. MODELS
ARE HAVING DIFFICULTIES RESOLVING THE TIMING OF THESE SHORTWAVES SO
HAVE LEFT POP GRIDS WITH MOSTLY SLIGHT TO LOW END POPS FOR NOW.
HIGH TEMPERATURES LOOK TO REMAIN STEADY IN THE UPPER 70S/LOW 80S
THROUGH THE PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 103 PM CDT WED MAY 22 2013

FORECAST THROUGH THURSDAY IS PLAGUED BY CLOUD COVER WITH PASSAGE
OF BACKDOOR COLD FRONT TONIGHT. SHOULD GET STRATUS IN THE VICINITY
OF THE FRONT...WHICH WOULD OCCUR ACROSS ALL OF WESTERN AND NORTH
CENTRAL NEBRASKA. MODELS WOULD SUGGEST THE STRATUS MOVING OUT OF
NORTH CENTRAL NEBRASKA BY 12Z...BUT WITH INVERSION SET UP...KEPT
THE STRATUS IN THROUGH MID MORNING AT KVTN AND KLBF. WINDS WILL
SWITCH OVER TO THE EAST BY THURSDAY MORNING...AND COULD GET SOME
GUSTS TO 20 MPH BY LATE MORNING. SHOULD THE STRATUS NOT DEVELOP AS
ANTICIPATED...FORECAST WILL IMPROVE GREATLY.


&&

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

&&

$$

SHORT TERM...BROOKS
LONG TERM...MARTIN
AVIATION...BROOKS