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000
FXUS63 KBIS 260006
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
706 PM CDT SAT MAY 25 2013

.UPDATE...
ISSUED AT 705 PM CDT SAT MAY 25 2013

TORNADO WATCH 217 REMAINS IN EFFECT UNTIL 10 PM MDT /11 PM CDT/
ACROSS SOUTHWESTERN ND. SEVERAL SEVERE THUNDERSTORM WARNINGS HAVE
BEEN ISSUED IN THE WATCH AREA...THOUGH NO TORNADO WARNINGS YET.
WITH REGARD TO THE UPDATE...MAINLY NUDGED CURRENT FORECAST TOWARD
OBSERVATIONS WITH NO CHANGES MADE TO POPS...WITH SHOWERS AND
THUNDERSTORMS CONTINUING TO PUSH EASTWARD. MODELS HAVE HAD
DIFFICULTY KEYING IN ON CONVECTIVE AREAS...MISSING EARLY MORNING
CONVECTION IN WESTERN ND. SOME OF THOSE STORMS REACHED SEVERE
CRITERIA. IN ADDITION TO CURRENT SEVERE THREAT ACROSS THE
SOUTHWEST...GFS/NAM/ECMWF DO SHOW AGREEMENT WITH DISTURBANCE
AFFECTING NORTHWESTERN ND LATER THIS EVENING. RADAR...SATELLITE
IMAGERY AND LIGHTNING NETWORK SHOW CONVECTIVE DEVELOPMENT ACROSS
PORTIONS OF NE MONTANA...WHICH WILL NEED TO BE MONITORED FOR
POSSIBLE MOVEMENT INTO ND.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 232 PM CDT SAT MAY 25 2013

MAIN FORECAST PROBLEM IN THE SHORT TERM WILL BE THUNDERSTORM
ACTIVITY TONIGHT THROUGH SUNDAY. CURRENT CONVECTION CONTINUES OVER
WESTERN NORTH DAKOTA...NORTH OF A FRONTAL BOUNDARY IN A GOOD SHEAR
ENVIRONMENT AND INCREASING MID LEVEL LAPSE RATES. THIS CONVECTION
HAS BEEN STRONG TO AT TIMES MARGINALLY SEVERE THROUGH THE MORNING
AND INTO THE EARLY AFTERNOON. EXPECT THIS TREND TO CONTINUE MAINLY
WEST OF THE HIGHWAY 83 CORRIDOR THROUGH THE AFTERNOON AND EARLY
EVENING.

NEXT AREA OF CONCERN WILL BE SOUTHEAST MONTANA INTO THE WESTERN
DAKOTAS LATE THIS AFTERNOON AND TONIGHT. UPPER LEVEL IMPULSE LIFTING
ACROSS THE NORTHERN ROCKIES WILL ERODE CINH. THIS...COMBINED WITH
DAYTIME HEATING WILL BE ENOUGH TO FIRE A FEW STORMS OVER THE HIGH
PLAINS. WITH STRONG DEEP LAYER SHEAR AND A STEEP EML...SOME
THUNDERSTORMS LIKELY BECOME SEVERE WITH LARGE HAIL THE MAIN THREAT.
ALTHOUGH WITH A GOOD SHEAR PROFILE AND LARGE CAPE VALUES...SOME OF
THE STORMS COULD PRODUCE TORNADOES. THINK THAT OVER TIME THIS
EVENING...CONVECTION WILL TRANSITION FROM DISCRETE CELLS TO A AN
MCS.

ON SUNDAY...NOT A LOT WILL CHANGE AS QUASI-STATIONARY LOW WILL
REMAIN OVER THE MONDAK REGION WITH A SOUTHWEST UPPER LEVEL FLOW.
WILL ADD A MENTION OF SEVERE STORMS TO THE WEST SUNDAY AFTERNOON.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 232 PM CDT SAT MAY 25 2013

UNSETTLED WEATHER WILL CONTINUE THROUGH MOST OF THE EXTENDED
PERIOD. THE UPPER LEVEL PATTERN WILL INITIALLY CONSIST OF A TROUGH
ALONG THE WEST COAST AND RIDGING OVER THE GREAT LAKES REGION
LEAVING THE NORTHERN PLAINS IN A SOUTHWEST FLOW. SPC CONTINUES TO
HIGHLIGHT A SLIGHT RISK OF SEVERE WEATHER FOR SOUTHWESTERN ND ON
MONDAY WITH THE GFS SHOWING 1000-2000 J/KG CAPE ACROSS MUCH OF THE
WESTERN HALF OF ND WITH A DEEPENING SURFACE LOW APPROACHING. BY
MIDWEEK GFS/ECMWF BRING THE TROUGH EASTWARD WHILE DEEPENING
IT...RESULTING IN A CONTINUED CHANCE OF PRECIPITATION ACROSS ND
THROUGH THE REMAINDER OF THE WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY AFTERNOON) ISSUED
AT 705 PM CDT SAT MAY 25 2013

MOST THUNDERSTORM ACTIVITY CONTINUES ACROSS SOUTHWESTERN ND AT
THIS TIME. OVERNIGHT...EXPECT SHOWERS AND THUNDERSTORMS TO
CONTINUE AT MANY LOCATIONS...MAINLY WEST AND CENTRAL WITH CEILINGS
ALSO LOWERING OVERNIGHT. EXPECT ALL TAF SITES TO BE EITHER MVFR
OR IFR BY 05Z...AND FOR CONDITIONS TO WORSEN OVERNIGHT AND EARLY
MORNING TOMORROW DUE TO LOW CEILINGS AND POSSIBLE LOWER
VISBILITIES DUE TO FOG. THE ASOS AT KDIK WILL REMAIN OUT OF SERVICE
UNTIL TUESDAY.

&&

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

$$

UPDATE...JNS
SHORT TERM...TWH
LONG TERM...JNS
AVIATION...JNS