939
FXUS63 KFGF 240204 AAA
AFDFGF
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GRAND FORKS ND
904 PM CDT WED JUL 23 2008
UPDATE
CHALLENGE TONIGHT IS TSTM POTENTIAL. INITIAL AREA OF SHOWERS OVER
NW MN MOVING GRADUALLY EAST. THIS IS ASSOC WITH 850 MB WARM/MOIST
ADVECTION. USING 18Z GFS FCST OF 850 MB THETA-E ADV WOULD EXPECT
MAJORITY OF THESE SHOWERS TO EXIT THE FCST AREA BY 06Z.
TO OUR WEST...LIES A COLD FRONT WHICH EXTENDS FROM SFC LOW
PRESSURE WEST OF YORKTON SASK THEN INTO NW ND AND SE MT. A SFC
TROUGH IS LOCATED FROM THE SFC LOW TO JUST EAST OF MINOT TO JUST
WEST OF BISMARCK. THERE WAS A PUNCH OF DRIER SFC AIR BEHIND THIS
TROUGH LATE THIS AFTN INTO WRN 1/2 OF THE STATE...BUT NOT SO SURE
THIS WILL CONTINUE AS WINDS DIMINISH. THUS HAVE A FEELING TROUGH
MAY JUST HANG UP IN CNTRL ND OVERNIGHT. HAD SOME CONVECTION FIRING
RIGHT ALONG TROUGH LATE THIS AFTN WHERE HIGHS REACHED NR 90 AND
DEW PTS REACHED 70. THESE CELLS MOVED EAST AND FOR THE MOST PART
ARE DYING. ONE EXCEPTION IS AREA OF TSTMS ASSOC WITH VORT MAX
WHICH IS MOVING THRU SE SASK INTO MANITOBA ATTM. SRN EDGE OF THIS
SYSTEM CLIPPING NCNTRL ND ATTM AND WE ARE SEEING A FEW CELLS WITH
THIS IN THE RUGBY AREA NORTHWARD. A FEW CELLS WITH THIS WILL
LIKELY CONTINUE AS VORT MOVES NORTHEAST. OTHERWISE UNCLEAR ABOUT
IF ANY MORE CONVECTION WILL FORM THE REST OF THE NIGHT OVER ERN ND
AND THE VALLEY AS 850 MB JET AND WARM ADV IS FCST TO POOL EITHER
TO OUR NORTH OVER THE INTERLAKE REGION OF MANITOBA OR TO THE SOUTH
ALONG THE SD/NE BORDER. WILL LEAVE SOME CHC POPS THRU THE NIGHT
ALL AREAS BUT TWEEK DOWN THE 50S TO MORE 30S.
LOWS LOOK REASONABLE.
PREV DISCUSSION
/ISSUED 238 PM CDT WED JUL 23 2008/
SHORT TERM...
MAIN CHALLENGES FOR THIS FORECAST DEAL WITH PCPN CHANCES AND
WHETHER ANY SEVERE TSTMS WILL BE POSSIBLE IN OUR FA LATE THIS
AFTERNOON AND OVERNIGHT. MODELS CONTINUE TO DO A POOR JOB HITTING
QPF WHERE IT IS CURRENTLY...SO DO NOT HAVE A GREAT DEAL OF
CONFIDENCE BEYOND TONIGHT. FOR THIS REASON WILL CONTINUE TO FOLLOW
FORECAST CONTINUITY MORE THAN ANY ONE MODEL SOLUTION.
TONIGHT...MODELS SHOW THE LOW LEVEL JET STAYING IN PLACE ACROSS
THE FA LATE THIS AFTERNOON AND TONIGHT...AT ABOUT 35 TO 40 KNOTS.
KMVX WSR88D CONFIRMS THIS TOO...DEPICTING A CONSISTENT 35 KNOTS IN
THE LOWEST GATES. IN CONJUNCTION...THERE IS BROAD WARM ADVECTION
IN THE SAME VICINITY TO HELP KEEP THESE WEAK TSTMS GOING. THIS
TREND SHOULD CONTINUE INTO TONIGHT...WITH TSTMS FORMING/DECAYING
..AND THE WHOLE COMPLEX SLOWLY TRANSLATING EAST WITH TIME. THE
SLIGHTLY STRONGER CELLS SEEM TO BE FORMING ALONG THE BACK EDGE AND
THEN WEAKENING AS THEY TRANSLATE EAST INTO THE DRIER/MORE STABLE
COLUMN. CLOUD COVER HAS LIMITED INSTABILITY OVER THE FA...WITH
TEMPS SO FAR STRUGGLING TO GET OUT OF THE UPPER 60S UNDER THE
THICKEST CLOUDS/RAIN. AS FAR AS ADDITIONAL TSTM REDEVELOPMENT...
WILL HAVE TO WATCH THINGS OUT WEST AGAIN FOR ANY SFC BASED TSTMS.
SFC LOW AND TROUGH STILL REMAIN OVER FAR WESTERN ND...WITH A
RIBBON OF MID TO UPPER 60 SFC DEW POINTS AHEAD OF IT. THIS AREA
HAS HEATED OUT NICELY AGAIN...WITH TEMPS APPROACHING 90F AND SFC
BASED LI'S NOW BELOW ZERO. STORMS COULD FIRE IN THIS AREA AND
CONTINUE TO PROGRESS EAST THRU THE NIGHT. THE SECOND POSSIBILITY
FOR REDEVELOPMENT TONIGHT WILL BE ELEVATED TSTMS ASSOCIATED WITH
THE LOW LEVEL JET. THE MODELS HAVE BEEN PRETTY CONSISTENT IN
DEPICTING THE MAIN FOCUS AREA JUST SOUTH OF THE FA...MAINLY FROM
SOUTHERN SD INTO IOWA.
THU/THU NIGHT...COULD BE SOME LINGERING PCPN IN THE EAST THU
MORNING BUT WHAT HAPPENS IN THE AFTERNOON IS QUESTIONABLE. MODELS
BRING THE SFC TROUGH/COLD FRONT SOMEWHERE CLOSE TO A LINE FROM THE
LAKE OF THE WOODS REGION DOWN THRU THE SOUTHERN VALLEY BY LATE
AFTERNOON. WITH MOISTURE STILL IN PLACE...IF SUN CAN BREAK THRU
ANY REMNANT CLOUD COVER AND ALLOW GOOD HEATING TO GET GOING...
TSTMS COULD BREAK OUT AGAIN CLOSE TO THE BOUNDARY. THIS SCENARIO
DOES NOT LOOK GREAT AT THIS POINT...SO WILL JUST KEEP PCPN CHANCES
LOW AND SEE IF MODELS DO BETTER WITH LATER RUNS. THE APPROACH OF
THE MAIN 500MB SHORT WAVE THU NIGHT COULD HELP FUEL SOME PCPN THRU
THE NIGHT.
FRI/SAT...500MB SHORT WAVE CONTINUES TO MOVE ALONG THE CANADIAN
BORDER ON FRI. SOME PIECES OF VORTICITY IN THE CYCLONIC FLOW AND
COOLER 500MB TEMPS COULD SPAWN SOME LIGHT SHOWERS/TSTMS...SO LEFT
IN THE LOW PCPN CHANCES HERE AS WELL. SFC HIGH BUILDS INTO THE
REGION ON SAT...FINALLY PUSHING THE PCPN TO THE EAST.
LONG TERM [SUN-WED]...
LONG TERM MODELS IN SLIGHT AGREEMENT WITH LONG TERM SETTING UP WITH
AN UPPER LEVEL RIDGE JUST WEST OF CWA...ALTHOUGH GFS SHOWS A
SLIGHTLY MORE AMPLIFIED RIDGE AND THE SFC HIGH IS A BIT FURTHER
EAST. REGARDLESS...SUN AND MON LOOK TO BE DRY AND THE NORTHERLY
FLOW OUT OF THE HIGH SHOULD HELP KEEP TEMPS DOWN INTO THE LOWER
80S...WHICH IS NEAR SEASONAL NORMS. ALTHOUGH TIMING IS A BIT
OFF...MODELS DO SHOW A WAVE MOVING ACROSS MAINLY THE NORTHERN CWA ON
TUESDAY...WITH TUE NIGHT LOOKING LIKE THE BEST CHANCE OF CONVECTION
IN THE LONG TERM.
AVIATION...
LOOK FOR PREDOMINANTLY VFR CONDS WITH TEMPO MVFR CIGS IN VCNTY OF
SHOWERS AND THUNDERSTORMS. LINE OF WEAK SHOWERS/STORMS MAINLY WEST
OF VALLEY AND SLOWLY MOVING TO THE EAST. CLEARING BEHIND THE LINE
SHOULD ALLOW ENOUGH HEATING FOR SOME MORE STORMS TO DEVELOP BEHIND
THIS AREA LATER ON TONIGHT. MOS GUIDANCE SHOWING LOWER CIGS
DEVELOPING EARLY TOMORROW MORNING...THUS HINTED AT SOME MVFR CONDS
IN THE NORTHERN VALLEY AFT AROUND 10Z.
FGF WATCHES/WARNINGS/ADVISORIES
ND...NONE.
MN...NONE.
RIDDLE/GODON
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