Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 190236
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
936 PM CDT THU SEP 18 2014

.UPDATE...

ISSUED AT 936 PM CDT THU SEP 18 2014

FORECAST REMAINS ON TRACK FOR THE LATE EVENING UPDATE. MAIN
MODIFICATIONS WERE TO POPS...TO ACCOUNT FOR THE EASTWARD
PROGRESSION OF CURRENT SHOWER ACTIVITY ACROSS THE SOUTH
CENTRAL...AND FOR A LARGE AREA OF SHOWERS/ISOLD THUNDER ACROSS
SOUTHEASTERN MONTANA MOVING EAST-NORTHEAST TOWARDS MY SOUTHWEST.


UPDATE

ISSUED AT 710 PM CDT THU SEP 18 2014

ROBUST CAPPING INVERSION KEEPING A LID ON STRONG CONVECTION EARLY
THIS EVENING ACROSS WESTERN AND CENTRAL NORTH DAKOTA DESPITE 1-2K
JOULES OF CAPE AND STRONG 0-6KM WIND SHEAR OF 40-45KTS. AN AREA OF
ELEVATED SHOWERS OVER THE SOUTHWESTERN QUARTER OF NORTH
DAKOTA...ASSOCIATED WITH A MID LEVEL IMPULSE...CONTINUES EASTWARD.
MODIFIED POPS BASED ON LATEST RADAR AND NEAR TERM HR MODEL
OUTPUT...TAKING THIS AREA OF PRECIPITATION EAST-NORTHEAST OVER THE
NEXT SEVERAL HOURS. GIVEN THE INSTABILITY PRESENT WILL MENTION AT
LEAST AN ISOLATED THUNDERSTORM CHANCE.

MID LEVEL SHORT WAVE APPROACHING THE INTERMOUNTAIN WEST AND
FORECAST TO MOVE EAST ACROSS THE NORTHERN PLAIN FRIDAY MORNING WILL
BRING A CONTINUED CHANCE FOR SHOWERS AND ISOLATED THUNDERSTORMS
ACROSS THE LOCAL AREA OVERNIGHT TONIGHT THROUGH FRIDAY MORNING.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 326 PM CDT THU SEP 18 2014

CONVECTIVE FORECAST CONTINUES TO BE COMPLICATED BY A RELATIVELY
STRONG LOW LEVEL CAPPING INVERSION ACROSS CENTRAL AND EASTERN
NORTH DAKOTA BUT WITH MID AND HIGH CAPE ABOVE AS MOST FLOW
OVERRIDES. WARM FRONT CURRENTLY EXTENDS FROM LOW PRESSURE IN
SOUTH CENTRAL SASKATCHEWAN SOUTHEAST THROUGH WESTERN NORTH DAKOTA.
WARM ADVECTION OVER THE WARM FRONT CURRENTLY GENERATING SOME
ELEVATED CONVECTION ACROSS NORTH CENTRAL NORTH DAKOTA AS CURRENT
NAM MODEL FAIRLY WELL PREDICTS. LATEST HRRR DOES NOT HANDLE THIS
WELL. CURRENT THINKING HAS THE MAJORITY OF CONVECTION WITH THE
COLD FRONT LATER TONIGHT. POPS FOR TONIGHT ARE STILL A BIT SPOTTY
OWING TO THE CAP...MOSTLY 20 TO 30 POPS. BY FRIDAY NORTHWEST FLOW
BEHIND THE COLD FRONT WILL SUPPRESS THUNDERSTORMS SOUTH AND
FOCUSED ON THE NORTH HALF FRIDAY AFTERNOON. LOWS TONIGHT 55 TO 65
AND HIGHS FRIDAY 78 TO 86.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 326 PM CDT THU SEP 18 2014

FRIDAY NIGHT THROUGH SATURDAY THE FORECAST AREA WILL BE UNDER THE
INFLUENCE OF NORTHWEST FLOW ALOFT WITH WEAK SHORT WAVES EMBEDDED IN
THE FLOW. THUS WILL KEEP THE SMALL CHANCE MENTION OF THUNDERSTORMS
MAINLY OVER NORTHERN COUNTIES.

THEN THE UPPER LEVEL WESTERN RIDGE PUSHES EASTWARD...ALONG WITH
SURFACE HIGH PRESSURE...BRINGING DRY CONDITIONS TO WESTERN AND
CENTRAL NORTH DAKOTA THROUGH MONDAY.

ALONG WITH THE WESTERN RIDGE...AN UPPER LEVEL LOW OVER CALIFORNIA
SATURDAY WILL MEANDER SLOWLY BENEATH THE RIDGE CREATING A REX BLOCK
OVER THE ROCKIES. BY EARLY NEXT WEEK THE WESTERN RIDGE BEGINS TO
PROGRESS EASTWARD AND THE MEANDERING UPPER LOW IS FORECAST TO MOVE
INTO THE PLAINS. MODELS ARE COMING INTO BETTER AGREEMENT AND LIFTING
THE UPPER LOW NORTHEASTWARD - APPROACHING NORTH DAKOTA ON TUESDAY.
THIS SLOW-MOVING LOW WILL BRING SOME CHANCE OF SHOWERS/THUNDER TO
THE REGION TUESDAY THROUGH THURSDAY...BUT CONFIDENCE IS NOT HIGH
REGARDING ITS IMPLICATIONS FOR PLACEMENT/TIMING OF PRECIPITATION.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)

ISSUED AT 710 PM CDT THU SEP 18 2014

LOW PRESSURE IN SOUTH CENTRAL SASKATCHEWAN WITH AN ASSOCIATED WARM
FRONT WILL MOVE EAST TONIGHT. THIS WILL BE FOLLOWED BY A COLD FRONT
LATE TONIGHT AND FRIDAY. SCATTERED TO WIDELY SCATTERED SHOWERS
AND THUNDERSTORMS WILL BE ASSOCIATED WITH THE WARM FRONT ACROSS
CENTRAL NORTH DAKOTA THIS EVENING. THE COLD FRONT WILL BE THE
FOCUS FOR SHOWERS AND THUNDERSTORMS ACROSS WEST AND CENTRAL
TONIGHT INTO FRIDAY MORNING...AND ACROSS NORTHERN NORTH DAKOTA
FRIDAY AFTERNOON. GIVEN THE STRONG CAPPING INVERSION...OPTED TO
USE VCSH AS THE OVERALL THUNDERSTORM THREAT WILL BE ISOLATED AT
BEST. OVERALL VFR IS EXPECTED.


&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...NH
SHORT TERM...WAA
LONG TERM...JV
AVIATION...NH






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