Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 180841
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
341 AM CDT MON AUG 18 2014

.SYNOPSIS...
ISSUED AT 341 AM CDT MON AUG 18 2014

H5 ANALYSIS FROM EARLIER THIS EVENING HAD A CLOSED LOW OVER
EASTERN QUEBEC WITH A TROUGH OF LOW PRESSURE EXTENDING SOUTH INTO
MAINE. FURTHER WEST...STRONG SHORTWAVES WERE NOTED OVER EASTERN
SASKATCHEWAN...THE LOWER OHIO VALLEY AND OVER WESTERN WASHINGTON
STATE. HIGH PRESSURE WAS ANCHORED ACROSS THE DESERT SOUTHWEST AND
EXTENDED NWD INTO THE CENTRAL ROCKIES. CLOSER TO WESTERN AND NORTH
CENTRAL NEBRASKA...A TROUGH ASSOCIATED WITH THE SHORTWAVE OVER
EASTERN SASKATCHEWAN...WAS IMPACTING THE WESTERN DAKOTAS AND
NORTHERN NEBRASKA. AS OF 2 AM CDT...PER WV IMAGERY...THE SHORTWAVE
HAD MOVED INTO SRN MANITOBA WITH THE TROUGH EXTENDING FROM CENTRAL
ND...SWD INTO NORTH CENTRAL NEBRASKA. A BROAD AREA OF SHRAS AND
THUNDERSTORMS WHICH IMPACTED CENTRAL AND NORTH CENTRAL NEBRASKA
EARLIER THIS EVENING...HAS PUSHED EAST TO SOUTHEASTERN NEBRASKA
AND EASTERN KANSAS. AT THE SURFACE...A WEAK TROUGH OF LOW PRESSURE
EXTENDED FROM NERN NEBRASKA INTO NWRN KS THIS MORNING. NORTH OF
THIS FEATURE...WINDS HAVE SHIFTED TO THE WEST OR WERE LIGHT AND
VARIABLE. UNDER CLEAR TO PARTLY CLOUDY SKIES...TEMPERATURES RANGED
FROM 56 AT VALENTINE AND AINSWORTH...TO 63 AT OGALLALA AND
IMPERIAL.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT MON AUG 18 2014

OVER THE NEXT 24 HOURS THE MAIN FORECASTING CHALLENGE WILL BE THE
LOW THREAT FOR THUNDERSTORMS IN SOME SWRN AREAS TONIGHT. FOR
TODAY...THE UPPER LEVEL DISTURBANCE...CURRENTLY OVER SRN
MANITOBA...WILL SLIDE TO THE EAST SOUTHEAST INTO NRN MINNESOTA BY
00Z TUESDAY. THE UPPER LEVEL TROUGH IN ASSOCIATION WITH THIS FEATURE
WILL PUSH INTO UPPER MISSISSIPPI VALLEY. NORTHERLY WINDS WILL
INCREASE ACROSS THE EASTERN DAKOTAS AND FAR NORTHEASTERN
NEBRASKA...WHERE A WEAK FRONT WILL TRY TO BACK INTO NORTHEAST NEBR
LATER TODAY. FURTHER SOUTHWEST...ANOTHER HOT DAY WILL BE IN STORE FOR
SWRN NEBRASKA. HOWEVER...IT WILL BE SLIGHTLY COOLER THAN YESTERDAY
AS HIGHS WILL ONLY REACH THE LOWER 90S IN FAR SWRN NEBRASKA.
ELSEWHERE...HIGHS WILL BE IN THE MID TO UPPER 80S. LATER THIS
EVENING...WITH SUNSET...THE FRONT WILL TRY TO BACK INTO
CENTRAL...THEN SWRN NEBRASKA OVERNIGHT. AT THE SAME
TIME...CONVECTION ACROSS THE HIGHER TERRAIN OF SERN WYOMING AND THE
SRN PANHANDLE...WILL ATTEMPT TO DRIFT TO THE EAST SOUTHEAST INTO FAR
SWRN NEBRASKA OVERNIGHT. ATTM...AM NOT EXPECTING ANY CONVECTIVE
INITIATION IN THE SWRN ZONES AS THE CAP WILL BE DECENT THIS
AFTERNOON AND EVENING...SO ANY STORMS WILL HAVE TO MOVE INTO THE
AREA FROM THE WEST. THAT BEING SAID...WILL CONFINE POPS TO THE FAR
SWRN ZONES...AND LIMIT THEM TO 20 PERCENT. WITH DEW POINTS EXPECTED
IN THE LOWER TO MID 50S IN THESE AREAS...CONVECTIVE POTENTIAL WILL
BE LIMITED AND STORM COVERAGE WILL BE ISOLATED AT BEST. LOWS TONIGHT
WILL GENERALLY BE IN THE MIDDLE 50S TO NEAR 60...THANKS TO DRIER
AIR.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 341 AM CDT MON AUG 18 2014

BEYOND 12Z TUESDAY. PRECIPITATION CHANCES TO HEADLINE THE
EXTENDED DISCUSSION AS SUPPORT FOR LATE WEAK SEVERE CONVECTION
APPEARS TO BE INCREASING.

INITIALLY STORM CHANCES LOOK TO BE SOMEWHAT CONDITIONAL EARLY IN THE
EXTENDED PERIOD AS A THERMAL RIDGE BUILDS ACROSS THE CENTRAL PLAINS
TUESDAY.  WARMING TEMPERATURES MAY CAP THE CONVECTIVE POTENTIAL
THROUGH MUCH OF THE DAY...BUT THE ARRIVAL OF A SHORTWAVE TUESDAY
EVENING MAY BE SUFFICIENT FOR STORM DEVELOPMENT.  THE DETERMINISTIC
MODELS INDICATE CONVECTION OFF THE HIGH PLAINS OF WESTERN NEBRASKA BY
00Z WEDNESDAY...THEN GENERALLY PUSH STORMS NORTHEAST ACROSS THE
SANDHILLS AND INTO NORTH CENTRAL NEBRASKA LATE EVENING/OVERNIGHT.  A
STRONG OR SEVERE STORM WILL BE POSSIBLE AS STEEP LOWER TO MID
TROPOSPHERIC LAPSE RATES PROMOTE MODEST INSTABILITY IN AN ATMOSPHERE
CHARACTERIZED WITH 30-40KTS OF 6KM BULK SHEAR.  HAIL WOULD REMAIN A
THREAT...BUT INVERTED PROFILES WOULD SUGGEST A GREATER THREAT OF
DAMAGING WIND.

UPPER RIDGE AXIS TO SHIFT EAST ACROSS THE MID MISSOURI VALLEY
WEDNESDAY...SOUTHWEST FLOW ALOFT WILL THEN PREVAIL AND DIRECT
ANOTHER SHORTWAVE ACROSS THE NORTHERN PLAINS. THE GREATEST FOCUS OF
AFTERNOON/EVENING CONVECTION IS SHOWN TO BE NORTH OF THE CWA WITH
THIS SHORTWAVE...HOWEVER A NORTHWARD RETREATING WARM FRONT AND/OR A
PRE-FRONTAL SFC TROUGH MAY SERVE AS A FOCUS FOR ADDITIONAL STORM
DEVELOPMENT LATE AFTERNOON ACROSS NORTH CENTRAL NEBRASKA. DESPITE
POSSIBLE MORNING CONVECTION IN THIS AREA...THE MODELS INDICATE THAT
THERMODYNAMIC PROFILES WILL RE-LOAD AND WOULD SUPPORT SEVERE
WEATHER.  HOWEVER 6KM BULK SHEAR VALUES DECREASE IN THE 20-30KT
RANGE...SO ATTM STRONG STORMS WOULD BE ANTICIPATED IF CONVECTION IS
REALIZED.

THE GFS AND EC POINT TO ANOTHER SW IMPULSE IMPACTING PORTIONS OF THE
CWA THURSDAY AFTERNOON INTO FRIDAY MORNING.  THE MODELS ARE KEYING
IN ON A FRONTAL BOUNDARY WITH AMPLE MOISTURE AND INSTABILITY IN
PLACE...STRONG OR SEVERE STORMS WOULD BE POSSIBLE GIVEN THE CURRENT
LONG TERM MODEL PROJECTIONS OF BULK SHEAR AND CAPE.  SIMILAR
FOR FRIDAY AND POSSIBLY SATURDAY AS THE UPPER LEVEL PATTERN BECOMES
MORE AMPLIFIED.  UPPER RIDGE WILL BUILD OFF TO OUR SOUTHEAST AS A
TROUGH DEEPENS OVER THE INTERMOUNTAIN WEST AND SHIFTS EAST TOWARD
THE NORTHERN/CENTRAL PLAINS.  THERE REMAINS DIFFERENCES IN TIMING OF
INDIVIDUAL WAVES/SFC FEATURES...SO WON/T GET TOO CARRIED AWAY WITH
THE FORECAST/HWO YET.  CRFCT_INT POPULATED A GOOD PORTION OF THE CWA
WITH 40-50 PERCENT POPS FRIDAY INTO SATURDAY...WHICH SEEMS A BIT
HIGH FOR CONVECTIVE POTENTIAL FIVE DAYS OUT ESPECIALLY FOR THE MONTH
OF AUGUST.  BUT DECIDED TO LEAVE THE BLENDED FORECAST AS IS FOR NOW
AS THIS LATE WEEK SETUP IS MORE REMINISCENT OF A LATE SPRING SEVERE
WX PATTERN RATHER THAN DURING THE DOG DAYS OF SUMMER.

TEMPERATURES THROUGH LATE WEEK ARE ANTICIPATED TO BE RATHER
MONOTONOUS...WITH HIGHS MAINLY IN THE UPPER 80S TO LOWER 90S...LOW
IN THE UPPER 50S TO MID 60S.   EXCITING THOUGH IS THE PROSPECTS OF A
COLD FRONTAL PASSAGE NEXT WEEKEND...WHICH WOULD TEMPORARILY COOL
HIGH TEMPERATURES INTO THE 80S FOR MOST LOCATIONS... SARCASTIC YAY!

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1131 PM CDT SUN AUG 17 2014

VFR CONDITIONS FOR THE KLBF AND KVTN TAFS THROUGH 06Z/19TH.
SCATTERED HIGH CLOUDINESS OVERNIGHT INTO MONDAY. NORTHERLY WINDS
AOB 12KTS TO SET IN AFTER 16Z.


&&

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

$$

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








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