Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 222344
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
644 PM CDT MON SEP 22 2014

.SYNOPSIS...
ISSUED AT 252 PM CDT MON SEP 22 2014

AT H5 RIDGE OVER WESTERN CONUS WITH UPPER CUTOFF LOW MOVING INTO
WYOMING. STRONG HUDSON BAY LOW WITH TROUGH INTO SOUTHEAST CONUS.
AT THE SURFACE A COLD FRONT EXTENDING FROM NORTHERN MAINE ALONG
THE ATLANTIC SEABOARD INTO EAST TEXAS. SURFACE HIGH PRESSURE
CENTERED OVER MISSISSIPPI RIVER VALLEY ALONG MISSOURI IOWA
BORDER. SURFACE TROUGH THROUGH THE NORTHERN ROCKIES.

&&

.SHORT TERM...(THIS AFTERNOON THROUGH TUESDAY)
ISSUED AT 252 PM CDT MON SEP 22 2014

TONIGHT AND TOMORROW.  PRECIPITATION CHANCES HEADLINE
THE SHORT TERM DISCUSSION...WITH THUNDER CHANCES BEING A SECONDARY
FOCUS.

THE NEAR TERM DETERMINISTIC SOLUTIONS...INCLUDING THE CONVECTIVE
ALLOWING RAP/HRRR CONTINUE TO INDICATE THE DEVELOPMENT OF WIDESPREAD
PRECIPITATION ACROSS MUCH OF THE OUTLOOK AREA LATE THIS AFTERNOON AND
TONIGHT.  THE PRECIPITATION IS ASSOCIATED WITH THE APPROACH OF A MID
LEVEL LOW PRESSURE SYSTEM THAT IS SHOWN TO EJECT EAST ACROSS WYOMING
AND THEN ONTO THE NORTHERN PLAINS EARLY TUESDAY.  SOUTHERLY LOWER
TROPOSPHERIC FLOW IN ADVANCE OF THE UPPER LOW HAS INCREASED PWAT
AMOUNTS ACROSS MUCH OF THE REGION IN EXCESS OF AN INCH AN A
QUARTER...WHICH IS NEAR 200 PERCENT OF NORMAL.  WITH THE APPROACH OF
THE LARGE SCALE LIFT...SHOWERS AND POSSIBLY STORMS WILL HAVE THE
POTENTIAL TO PRODUCE MEASURABLE QPF...AND IN SOME CASES...RAINFALL
RATES MAY APPROACH A QUARTER OF AN INCH PER HOUR...WITH TOTAL
ACCUMULATIONS POSSIBLY ECLIPSING A HALF OF AN INCH ACROSS OUR
EASTERN ZONES AND NORTHEAST.  THE CONVECTIVE POTENTIAL THIS EVENING
AND OVERNIGHT HAS DECREASED SOMEWHAT...DUE MAINLY IN PART TO THE
LACK OF DESTABILIZATION OF THE ATMOSPHERE AS A PERSISTENT DECK OF
CLOUDS HAVE ENCOMPASSED MUCH OF THE CWA TODAY.  THAT BEING SAID
THERE HAS BEEN A FEW BREAKS...ESPECIALLY WEST AND EAST...WITH THE
LATEST MESOANALYSIS INDICATING 50-100 J/KG OF MUCAPE IN PLACES.
DEBATED PULLING ALL MENTION OF THUNDER FROM THE FORECAST THIS
EVENING/OVERNIGHT...BUT WILL LEAVE AN ISOLATED MENTION IN AS A CG
STRIKE OR TWO IS NOT ENTIRELY OUT OF THE QUESTION.  THE ACTIVITY IS
ANTICIPATED TO SHIFT EAST ACROSS THE CWA THIS EVENING AND
OVERNIGHT...TRENDED THE FORECAST TO ACCOUNT FOR THIS AND TRIED TO
INCLUDE A LIKELY MENTION WHERE PRECIPITATION CONFIDENCE IS HIGH
ENOUGH.

CENTRAL PORTIONS OF THE FORECAST AREA REMAIN UNDER A 5% OUTLOOK FOR
SEVERE STORMS ON TUESDAY AS THE MID-LEVEL LOW/TROUGH ADVANCES SLOWLY
EAST ACROSS THE DAKOTAS AND SOUTHERLY FLOW PULLS MOISTURE NORTHWARD
ACROSS THE SANDHILLS INTO THE LOW.  SHOWERS AND POSSIBLY A THUNDERSTORM
OR TWO SHOULD BE ONGOING ACROSS OUR EASTERN ZONES EARLY
TUESDAY...BUT CLEARING AND SUBSEQUENT DIABATIC SURFACE HEATING WILL
SERVE TO DESTABILIZE THE ATMOSPHERE WHERE THE MOISTURE ADVECTION IS
OCCURRING.  MODEL GUIDANCE SUGGESTS A WEAKLY MODERATE UNSTABLE
ATMOSPHERE CHARACTERIZED BY 500-1000 J/KG OF MLCAPE BY LATE
AFTERNOON...AND WITH EFFECTIVE SHEAR OF 25-30KTS IN PLACE...ISOLATED
STORMS CAPABLE OF MARGINALLY SEVERE HAIL WOULD BE POSSIBLE BEFORE
DARK.  WILL MAKE NO BIG CHANGES TO THE INHERITED FORECAST DURING THE
DAY TUESDAY...WHICH INDICATES A 20-30% CHANCE OF STORMS.  WILL ALSO
CONTINUE TO MENTION A LOW END SEVERE THREAT IN THE HWO.

HIGHS TUESDAY WILL BE COOL ONCE AGAIN FOR MUCH OF THE CWA...BUT A
SURFACE TROUGH WILL CROSS INTO THE WESTERN SANDHILLS WITH STRONG WAA
IN IT/S WAKE.  WHERE THE BOUNDARY CROSSES...LOCATIONS TO THE WEST
MAY SEE HIGHS RETURN BACK INTO THE 80S.  EAST OF THE SFC
FEATURE...UPPER 60S TO MID 70S SHOULD PREVAIL.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 252 PM CDT MON SEP 22 2014

MID TERM MODELS ARE IN GOOD AGREEMENT AND IN THE LONG TERM MODELS
BEGIN TO DIVERGE. HAVE GOOD CONFIDENCE IN FORECAST. TUESDAY NIGHT
THUNDERSTORMS TO CONTINUE OVER WESTERN NEBRASKA. MUCAPE VALUES OF
1500 TO 2500 AT 00Z FROM AINSWORTH TO BROKEN BOW. DYNAMICS WILL
DECREASE WITH THE HEATING OF THE DAY AND AS THE 850MB LLJ MOVES
QUICKLY EAST. PRECIPITATION TO MOVE ACROSS NORTH CENTRAL NEBRASKA
THROUGH THE EARLY MORNING HOURS AND ENDING EARLY WEDNESDAY
MORNING. ON THE BACKSIDE OF THE UPPER SYSTEM INCREASING HEIGHTS
AND WARMER AIR MOVING IN FROM THE SOUTHWEST. SOME RESIDUAL
CLOUDINESS DURING THE DAY OVER NORTHERN NEBRASKA IN DEFORMATION
ZONE. LIGHT RAINSHOWERS POSSIBLE BUT HAVE LEFT DRY FOR NOW. HIGHS
IN THE 80S WEST AND 70S EAST WEDNESDAY AND THURSDAY. FRIDAY AND
SATURDAY RIDGE HOLDS OVER NORTHERN PLAINS WITH UPPER TROUGH
MOVING EAST ACROSS THE WESTERN CONUS HIGHS IN THE 80S AND DRY.
INCREASING CLOUDS SUNDAY WITH PRECIPITATION SUNDAY NIGHT MONDAY OVER
WESTERN NEBRASKA. HIGHS IN THE 70S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 643 PM CDT MON SEP 22 2014

SHOWERS...WITH EMBEDDED THUNDERSTORMS...WILL BE POSSIBLE ACROSS
WESTERN AND NORTH CENTRAL NEBRASKA INTO THE OVERNIGHT HOURS. CIGS
WILL GENERALLY BE VFR INTO THE OVERNIGHT. SOME MVFR CIGS ARE
POSSIBLE OVERNIGHT TONIGHT INTO EARLY TUESDAY MORNING AT THE KVTN
TERMINAL. SOME LIMITED CLEARING IS POSSIBLE TUESDAY
AFTERNOON...PARTICULARLY AT THE KLBF TERMINAL. AT THE KVTN
TERMINAL...EXPECT CLOUDY SKIES TUESDAY WITH CIGS RANGING FROM 5000
TO 10000 FT AGL.

&&

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

$$

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






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