Severe Thunderstorm Warning 267, NWS Grand Forks, ND

FORECAST DISCUSSION FOR EASTERN NORTH DAKOTA AND NORTHWEST
MINNESOTA...CORRECTED FOR TIME
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
255 PM CDT TUE SEP 5 2000

FORECAST CHALLENGE CONCERNS TSRA AND TEMPS.

OVERALL MODELS IN SIMILAR AGREEMENT WITH OVERALL FEATURES. ETA HAS
PERFORMED WELL OVER PAST SEVERAL DAYS WITH CURRENT PATTERN AND WILL
UTILIZE FOR DETAILS.

NORTHERN STREAM S/W TO PUSH EAST WHICH WILL SHIFT LOW LEVEL
BOUNDARY/COLD FRONT WHICH HAS BEEN STATIONARY OVR E MT/W ND PAST FEW
DAYS EASTWARD TOWARDS FA. CONVECTION WHICH DEVELOPED IN MOIST AXIS
AND IN ZONE OF WAA ON NOSE OF APPROACHING UPPER JET WILL CONTINUE TO
PROPAGATE E-NE AFFECTING WESTERN HALF OF FA IN THE NEAR TERM.
STRONGEST CONVECTION LOCATED ALONG AND NORTH OF INL BORDER AREA
WHICH APPEARS TO BE ENHANCED BY STRONGER CONVERGENCE NEAR LOW LEVEL
BOUNDARY. EARLY IN PERIOD EXCEPT FOR FAR NORTH WOULD EXPECT EASTWARD
PROPAGATION MUCH PAST RRV LIMITED DUE TO LACK OF ELEVATED
INSTABILITY AND MOIST.

OVERNIGHT H8 THETA-E RIDGE AND INSTABILITY AXIS WORKS EAST INTO FA.
AS H8 50 KT LOW LEVEL JET SHIFTS EAST OVR FA AND WAA INCREASES
EXPECT CONVECTION TO BECOME MORE WIDESPREAD ACROSS FA AHEAD OF WAVE
AND COLD FRONT. SIZEABLE CAP TO OVERCOME ACROSS THE SOUTH AS H7
+10-12 TEMPS SPREAD EAST. THIS WOULD PUT FAVORABLE LOCATION FOR PCPN
ACROSS NORTHERN 2/3 FA. PTNS OF NW COUNTIES HAVE RECIEVED HEAVY
RAINFALL PAST 24 HOURS AND IF ADDNL CONVECTION BECOMES ORGANIZED IN
THIS AREA MAY NEED TO CONSIDER FLASH FLOOD HEADLINES AS 3 HOUR
GUIDANCE UNDER AN INCH. IN ADDITION PAST HISTORY WITH EVENTS WOULD
INDICATE ELEVATED SVR THREAT POSSIBLE ACROSS NORTHWEST. WINDS WILL
CONTINUE STRONG OVERNIGHT IN TIGHT GRADIENT. INCREASING CLOUD
COVER...WIND TO HOLD TEMPS UP AND WILL GENERALLY FOLLOW GUIDANCE.

COLD FRONT TRACKS EAST ACROSS FA TOMORROW. WITH CAPPING IN PLACE
WILL PUT HIGHEST POPS ACROSS NORTHERN HALF OF FA. WILL TIME PCPN
THREAT FROM WEST TO EAST AHEAD OF CFP. WITH CLOUDS AND PCPN FEEL FWC
GUIDANCE TOO HIGH AND WILL LEAN MORE TOWARDS MAV GUIDANCE.

HIGH PRESSURE BUILDS INTO FA FROM WEST TO EAST WED EVENING INTO
THURSDAY WHICH WILL BRIEFLY BRING AN END TO PCPN. LACK OF STRONG CAA
SHOULD AND SOLAR SHOULD ALLOW TEMPS TO REACH NORMAL RANGE.

EXTENDED FORECAST...MODELS HAVE SIMILAR TRENDS...BUT STILL HAVE
TIMING DIFFERENCES. THE MRF MATCHES THE ECMWF SOLUTION THE BEST WITH
THE UKMET THE FASTEST. 500 MB RIDGE HOLDS OVER CWFA ON FRI ALONG
WITH SFC HIGH...KEEPING CWFA DRY. BY 12Z SAT...NEXT UPPER LEVEL TROF
HAS MOVED TOWARDS CWFA WITH SFC LOW DEVELOPING IN THE CENTRAL
PLAINS...PROVIDING THE NEXT OPPORTUNITY FOR PCPN OVER CWFA ON SAT
AND SUN. FOR MON...UPPER LEVEL FLOW GOES SW AS CWFA UNDER INFLUENCE
OF WEAK SFC HIGH PRESSURE RIDGE AND SFC LOW MAINTAINS ITS PRESENCE
IN CENTRAL PLAINS...SO KEPT FORECAST DRY. FOR MON NIGHT AND
TUE...SFC LOW STARTS TO LIFT NE...PUTTING CWFA ONCE AGAIN ON TRACK
FOR POSSIBLE TSRA...WHICH INCLUDED IN TUE FORECAST. AS FAR AS
TEMPS...MRF SFC TEMPS WARMER THAN FMR GUIDANCE FOR LOWS...BUT PRETTY
SIMILAR FOR HIGHS. THEREFORE...UTILIZED COOLER FMR GUIDANCE NUGMBERS
FOR LOWS (WHICH WERE IN LINE WITH CURRENT FORECAST TRENDS) AND STUCK
WITH CURRENT TRENDS FOR HIGHS.

.FGF...NONE

VOELKER/NG