Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 190837
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
337 AM CDT TUE AUG 19 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 337 AM CDT TUE AUG 19 2014

UPPER TROUGH OVER GREAT LAKES DRUG A SURFACE COOL FRONT THROUGH
NEBRASKA LAST NIGHT WITH REMNANTS OF CONVECTION EXITING SOUTHEAST
NEBRASKA EARLY THIS MORNING. WEAK RIDGING INTO THE NORTHERN ROCKIES
PLACING WESTERN NEBRASKA IN FAST NORTHWEST FLOW. CLOSED LOW OVER
CENTRAL CALIFORNIA COAST AS SEEN IN WATER VAPOR. SKIES GENERALLY
CLEARING EARLY THIS MORNING OVER WESTERN NEBRASKA WITH SOME WEAK
CONVECTION OVER NORTHEAST COLORADO. WILL HAVE TO TAKE A LAST MINUTE
LOOK TO SEE WHETHER TO INCLUDE ISOLATED POPS OVER SOUTHWEST ZONES
EARLY THIS MORNING. RIDGE WILL BEGIN TO FLATTENING SOME AS A STRONG
MID LEVEL WAVE MOVES OUT OF THE BOTTOM OF THE CLOSED LOW TO THE
WEST. FRONT RANGE WILL SEE EFFECTS OF THIS UPPER WAVE INITIALLY THIS
AFTERNOON. SOUTHERLY FLOW WILL INCREASE THIS MORNING AND ADVECT
MOISTURE INTO WESTERN NEBRASKA THIS AFTERNOON. SURFACE LOW TO
DEVELOP OVER NORTHWEST KANSAS THROUGH THE DAY IN RESPONSE TO UPPER
WAVE. HIGHS IN THE UPPER 80S NORTH AND LOW 90S SOUTHWEST WITH DEW
POINTS RISING INTO THE MID 60S. CONVECTION TO MOVE OFF FRONT RANGE
AND WILL AFFECT THE NEBRASKA PANHANDLE THIS AFTERNOON AND EXPAND
EAST INTO WESTERN NEBRASKA THIS EVENING. BOUNDARY OVER NORTHERN
NEBRASKA WILL BE THE FOCUS FOR THUNDERSTORMS TUESDAY NIGHT INTO
WEDNESDAY MORNING.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 337 AM CDT TUE AUG 19 2014

BEYOND 12Z WEDNESDAY. THE PRIMARY FOCUS OF THE LONG TERM
DISCUSSION WILL BE ON NEAR DAILY STORM CHANCES...WITH PERIODIC
SEVERE WEATHER POSSIBLE FOR PORTIONS OF THE CWA. NOT ALL AREAS
WILL EXPECT DAILY QPF...BUT AN ACTIVE PATTERN APPEARS POSSIBLE.

THE SYNOPTIC PATTERN ACROSS THE CONTIGUOUS 48 WILL AMPLIFY MID TO
LATE WEEK AS AN UPPER LEVEL RIDGE BUILDS NORTHWARD ATOP THE MIDWEST
AND INTO THE GREAT LAKES REGION WHILE THE WESTERN CONUS TROUGH
ADVANCES ACROSS THE ROCKIES.  THIS PATTERN WILL FAVOR ACTIVE
SOUTHWEST FLOW ALOFT ATOP THE CENTRAL HIGH PLAINS WEDNESDAY THROUGH
EARLY NEXT WEEKEND...WITH THE PERIODIC PASSAGE OF SHORTWAVE IMPULSE
PASSING THROUGH THE MEAN FLOW.  AT THE SURFACE...A MEANDERING WARM
FRONT WILL BE WITHIN THE REGION...WITH OTHER BOUNDARIES AND/OR SFC
LOWS SHOWN TO BE A INFLUENCE TO THE CWA.

WEDNESDAY...SEVERE STORMS WILL BE POSSIBLE BY LATE AFTERNOON ACROSS
OUR NORTH CENTRAL NEBRASKA ZONES.  THE MID RANGE DETERMINISTIC
MODELS AGREE THAT A WARM FRONT WILL RETREAT NORTH DURING THE DAY AND
TAKE UP RESIDENCE FROM CENTRAL SD SOUTHEAST THROUGH NORTH CENTRAL
NEBRASKA.  UNDER STRONG SOLAR ISOLATION...THE ATMOSPHERE IS EXPECTED
TO RE-LOAD AND BECOME MODERATELY TO STRONGLY UNSTABLE WITHIN
INCREASING DEEP LAYER SHEAR OF 25-35KTS OR SO.  LARGE HAIL WILL BE
POSSIBLE IN SUPERCELLS THAT DEVELOP.  BUFR SOUNDINGS ACROSS NC NEB
REVEAL INVERTED PROFILES IN THE LOWEST 7K FEET OF THE
TROPOSPHERE...A DAMAGING WIND THREAT WOULD BE POSSIBLE AS WELL.
ISOLATED STORMS MAY BE POSSIBLE ALONG THE TRAILING SFC TROUGH SOUTH
OF THE LIFTING LOW/WARM FRONT...HOWEVER WITH LESSER
CAPE/MOISTURE/SHEAR ANTICIPATED TO BE IN PLACE...WIDESPREAD SEVERE
WEATHER ACROSS OUR SOUTHEASTERN ZONES IS NOT EXPECTED.

THURSDAY INTO EARLY FRIDAY...ADDITIONAL WEAK SW IMPULSES ARE
INDICATED TO TRACK FROM THE SOUTHERN ROCKIES TOWARD THE CENTRAL
PLAINS AND INTERACT WITH WEAK SFC LOW PRESSURE/WARM FRONT LOCATED
ACROSS SOUTHWEST NEBRASKA.  SUFFICIENT FORCING FOR ISOLATED STORMS
IS SHOWN BY THE DETERMINISTIC MODELS...AND IF STORMS ARE
REALIZED...MODEST INSTABILITY COULD PROMOTE A SEVERE STORM OR TWO BY
LATE AFTERNOON.

FRIDAY AND BEYOND...THE PATTERN REMAINS POTENTIALLY ACTIVE WITH
ADDITIONAL ATMOSPHERIC IMPULSES IMPACTING WITH AN UNSTABLE
ATMOSPHERE AND VARIOUS LOWER TROPOSPHERIC BOUNDARIES.  THE MODELS
THE LAST FEW RUNS HAVE STRUGGLED WITH TIMING AND LOCATION WITH NOT
ONLY THE FINER SCALE FEATURES OF THE SW IMPULSES...BUT ALSO WITH THE
HANDLING OF THE LARGE SCALE MEAN TROUGH.  THUS CONFIDENCE IN THE
CONVECTIVE FORECAST FRIDAY THROUGH THIS WEEKEND IS LOW...AND FOR
THIS OPTED TO KEEP POPS THIS WEEKEND BELOW 50 PERCENT AT THIS TIME.
THE BEST SHOT OF WIDESPREAD STORMS APPEARS TO ARRIVE LATE SATURDAY
NIGHT INTO SUNDAY WITH THE ARRIVAL OF A CANADIAN COLD FRONT.

AFTER HIGHS IN THE 80S AND 90S THROUGH FRIDAY...TEMPERATURES WILL COOL
SATURDAY AND ESPECIALLY SUNDAY INTO EARLY NEXT WEEK AS A COOL
CANADIAN AIRMASS SETTLES SOUTH BEHIND THE COLD FRONT.  HIGHS SUNDAY
AND EARLY NEXT WEEK MAY FALL SOME 10-15 DEGREES BELOW CLIMO.  LOWS
THROUGH THE EXTENDED SHOULD REMAIN IN THE 60S FOR MOST
PLACES...HOWEVER BEHIND THE CANADIAN COLD FRONT...WIDESPREAD LOWS IN
THE 50S SHOULD BE THE NORM.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1251 AM CDT TUE AUG 19 2014

VFR CONDITIONS FOR THE KLBF AND KVTN TERMINALS OVERNIGHT AND
TUESDAY. AN APPROACHING DISTURBANCE WILL TRIGGER SCATTERED
THUNDERSTORMS LATE TUESDAY AFTERNOON AND TUESDAY NIGHT.
THUNDERSTORMS ARE MORE LIKELY TO AFFECT THE KVTN TERMINAL TUESDAY
EVENING...AND FROM THE LATEST MODEL OUTPUT...HAVE INCLUDED A TEMPO
FOR 5SM TSRA FROM 03Z-06Z.

&&

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

$$

SHORT TERM...POWER
LONG TERM...JACOBS
AVIATION...POWER










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