000
FXUS63 KBIS 041614
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
1114 AM CDT SAT JUL 4 2009

.UPDATE...

UPDATES THIS MORNING WERE BASED ON LATEST RADAR AND SATELLITE
IMAGERY. IT WOULD APPEAR THAT THE 800 OR SO J/KG CAPE AXIS ALONG
U.S. HIGHWAY 83 WILL NOT BE SUFFICIENT TO CAUSE STORMS TO BECOME
SEVERE. SO...WILL SIMPLY KEEP AN EYE ON EVERYTHING THIS MORNING
AND AFTERNOON...TAKING CARE NOT TO RULE OUT SOME THUNDERSTORMS
WITH SMALL HAIL AND BRIEF GUSTY WINDS. 

&&

.PREV DISCUSSION... /ISSUED 300 AM CDT SAT JUL 4 2009/ 

SHORT TERM...TODAY THROUGH MONDAY NIGHT...
OVERALL PATTERN IN THE SHORT TERM SHOWS AN AMPLIFYING RIDGE
STRETCHING FROM THE FOUR CORNERS INTO THE NORTHERN ROCKIES WITH
THE RIDGE AXIS SHIFTING INTO NORTH DAKOTA BY 12Z TUESDAY. UP UNTIL
THAT TIME...NORTH DAKOTA WILL BE UNDER THE INFLUENCE OF A WEAK
NORTHWEST FLOW WITH WITH DISTURBANCES RIDING THROUGH. THESE
DISTURBANCES IN COMBINATION WITH WEAK SURFACE REFLECTIONS/TROUGHS
AND AN ALREADY UNSTABLE ATMOSPHERE WILL RESULT IN SCATTERED
SHOWERS/THUNDERSTORMS OVER PORTIONS OF THE CWA TODAY AND SUNDAY.

FOR TODAY...FOLLOWED A BLEND OF THE NAM/GFS/4KM WRF. LATEST
SURFACE ANALYSIS SHOWS A SURFACE LOW/TROUGH OVER SOUTHERN
SASKATCHEWAN. BOTH THE NAM AND GFS SHOW THIS TROUGH MOVING
SOUTHEAST ACROSS NORTHERN NORTH DAKOTA THROUGH THE MORNING AND
INTO CENTRAL AND SOUTHERN NORTH DAKOTA MID AFTERNOON THROUGH THE
EARLY EVENING. THIS TROUGH WILL PROVIDE A CONVERGENCE/FOCUSING
MECHANISM TO GET CONVECTION STARTED. WITH THE APPROACH OF AN UPPER
DISTURBANCE AND THE NAM BUFR SOUNDINGS SHOWING AN UNSTABLE/INVERTED-V
TYPE PROFILE...HIGH CAPE AND DECENT SHEAR WILL YIELD WIND AND HAIL
AS THE MAIN THREATS. ALSO PRECIPITABLE WATER VALUES STILL
SLIGHTLY ABOVE ONE INCH AND K INDICES AROUND 30 INDICATE THAT
THUNDERSTORMS MIGHT PRODUCE HEAVY RAIN ONCE THE ENVIRONMENT
OVERCOMES THE INVERTED V PROFILE AND CLOUD BASES BEGIN TO LOWER.
EXPECT ACTIVITY TO DIMINISH BY AROUND SUNSET OVER OUR FAR SOUTHERN
AND SOUTHEASTERN CWA. EXPECTING DRY CONDITIONS AFTER SUNSET AND
FOR THE REMAINDER OF THE NIGHT.

ON SUNDAY...ANOTHER UPPER WAVE MIGRATES THROUGH DURING THE DAY
WHICH WILL INITIATE SOME SHOWER/THUNDERSTORM ACTIVITY. SOUNDINGS
ARE NOT AS UNSTABLE AS TODAY WITH SOME WEAK CIN SHOWING UP AND
OVERALL CAPE MUCH LESS...THUS FEEL SLIGHT CHANCE WILL SUFFICE FOR
NOW. H85 TEMPS CONTINUE TO SHOW A WARMING TREND AND ANOTHER COUPLE
OF DEGREES OF WARMING AT THE SURFACE CAN BE EXPECTED.

SUNDAY NIGHT THROUGH MONDAY NIGHT...THE RIDGE AXIS BEGINS TO EDGE
CLOSER INTO NORTH DAKOTA BEFORE MOVING OVERHEAD MONDAY NIGHT.
SUNDAY NIGHT INTO MONDAY AFTERNOON LOOKS MOSTLY DRY...THEN A
SHORTWAVE RIDES THROUGH THE RIDGE TOP OFFERING SOME POTENTIAL OF
SHOWERS AND THUNDERSTORMS MONDAY NIGHT OVER OUR NORTHWEST AND
NORTH CENTRAL ZONES. 

LONG TERM...TUESDAY THROUGH SATURDAY...
EXTENDED GRIDS BEGIN WITH SHARP RIDGE OVER CENTRAL CONUS PINCHED 
BETWEEN LOWS OVER PACIFIC NORTHWEST AND SECOND LOW NORTH OF GREAT 
LAKES. ECMWF AND GEM IN FAIR AGREEMENT AND WILL USE ECMWF FOR GRIDS. 

MID LEVEL ENERGY PUSHES LEE TROUGH INTO STATE ON TUESDAY WITH EC 
PAINTING BROAD AREA OF SIGNIFICANT PRECIPITATION OVER STATE BOTH 
TUESDAY AND WEDNESDAY. MAIN PACIFIC NORTHWEST LOW MOVES EAST NORTH 
OF CANADIAN BORDER ON THURSDAY  WITH COOLER AND DRIER CONDITIONS FOR 
END OF THE WEEK. HIGH PRESSURE DOMINATES THE NORTHERN PLAINS INTO 
WEEKEND AS MID LEVEL RIDGE REBUILDS OVER CENTRAL CONUS INTO SOUTH 
CENTRAL CANADA. 

SHARP TROUGH APPROACHES STATE AT END OF EXTENDED FOR NEXT ROUND OF 
POSSIBLE SEVERE CONVECTION JUST BEYOND FORECAST PERIOD. 

AVIATION...
LINGERING CONVECTION WESTERN TAF SITES AS WELL AS PATCHY BR WILL BE 
AVIATION CONCERNS TONIGHT. 

&&

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

$$

KS/HW/SCHECK