Area Forecast Discussion
Issued by NWS Grand Forks, ND

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000
FXUS63 KFGF 040830
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
330 AM CDT SAT JUL 4 2015

.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 330 AM CDT SAT JUL 4 2015

SEVERE T-STORM POTENTIAL TODAY...AND THEN AGAIN ON SUNDAY WILL BE
THE MAIN CONCERNS. 00Z MODELS IN DECENT AGREEMENT WITH SYNOPTIC
FEATURES.

TODAY-TONIGHT...SPC HAS ADDED A SLIGHT RISK OF SEVERE STORMS FOR
EASTERN NORTH DAKOTA. WATER VAPOR IMAGERY INDICATES A LEAD
SHORTWAVE ACROSS EASTERN MONTANA THAT WILL PROVIDE FORCING ACROSS
EASTERN NORTH DAKOTA DURING THE AFTERNOON HOURS. ADDITIONAL STORMS
ARE EXPECTED TO DEVELOP ACROSS WESTERN NORTH DAKOTA ALONG A COLD
FRONT AND THEN MOVE INTO THIS AREA. CAM GUIDANCE SUGGESTS COVERAGE
WILL REMAIN ISOLD/SCATTERED. MOST GUIDANCE SUGGESTS MLCAPE
1000-2000 J/KG...WITH INCREASING 0-6KM BULK SHEAR (TO AROUND 30
KNOTS) THROUGH THE AFTERNOON AS THE MORE SUBSTANTIAL TROUGH IN
CANADA APPROACHES. THIS INSTABILITY/SHEAR COMBINATION SHOULD LEAD
TO ORGANIZED STORMS WITH MARGINALLY SEVERE HAIL AND WIND THE MAIN
THREATS.

THE SURFACE SMOKE REDUCING VSBY SHOULD DISPERSE A BIT DURING THE
AFTERNOON AS LOW LEVEL WINDS INCREASE.

SUNDAY-SUNDAY NIGHT...ECMWF/GEM HAVE SLOWED DOWN THE PROGRESSION
OF THE COLD FRONT ON SUNDAY...AND LIKEWISE ARE FURTHER NORTH WITH
AN UPPER WAVE SUNDAY NIGHT (COMPARED TO THE GFS/NAM). THE
ECMWF/GEM SOLUTION WOULD INCREASE THE SEVERE POTENTIAL FOR SUNDAY
AFTERNOON...AND ALSO LEAD TO A GREATER THREAT FOR HEAVY RAINFALL
(FLASH FLOODING) POTENTIAL ACROSS THE SOUTHERN FA SUNDAY NIGHT.
REGARDING THE SEVERE POTENTIAL ON SUNDAY...THE MAIN QUESTION STILL
REMAINS HOW QUICKLY THE STRONGER DEEP LAYER SHEAR CAN OVERSPREAD
THE REGION. THERE WILL BE MODERATE INSTABILITY ALONG AND AHEAD OF
THE SFC BOUNDARY SUNDAY AFTERNOON...IT IS JUST A MATTER HOW
QUICKLY THE SFC BOUNDARY MOVES TO THE SOUTHEAST (WILL IT REMAIN
AHEAD OF THE STRONGER DEEP LAYER SHEAR?). WOULD NOT BE SURPRISED
TO SEE SPC UPGRADE THE MARGINAL RISK TO A SLIGHT RISK EVENTUALLY.
STORM MOTION WILL LIKELY BE PARALLEL TO THE SURFACE BOUNDARY
SUNDAY AFTERNOON/EVENING...AND WITH PWATS ABOVE 1.5 INCHES ANY
TRAINING TYPE STORMS COULD LEAD TO HEAVY RAINFALL. IF THIS
OCCURS...WILL BE VERY CONCERNED FOR AN ADDITIONAL 1-3 INCHES THAT
COULD OCCUR TOWARD MONDAY MORNING IF THE ECMWF/GEM ARE CORRECT.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 330 AM CDT SAT JUL 4 2015

MONDAY...MUCH COOLER AIRMASS WILL INVADE THE REGION LEADING TO MAX
TEMPS BARELY REACHING 70F. COLD POOL ALOFT SHOULD LEAD TO AT LEAST
ISOLD AFTERNOON SHOWERS/T-STORMS.

TUESDAY-FRIDAY...MEDIUM RANGE MODELS STILL AGREE ON STARTING OUT
EXTENDED PERIOD AS DRY WITH BELOW AVERAGE TEMPERATURES AS HIGH
PRESSURE BUILDS INTO THE UPPER MIDWEST. SPLIT FLOW RULES AS THE
NEXT SHORTWAVE TROUGH ENTERS THE NORTHERN PLAINS ON WEDNESDAY
SPAWNING ANOTHER ROUND OF AT LEAST SCATTERED THUNDERSTORMS. THE
ECMWF REMAINS FASTER THAN THE GFS IN TIMING THE WAVE THROUGH THE
REGION. BLENDING PROTOCOLS YIELD HIGHER POPS ON
WEDNESDAY/WEDNESDAY NIGHT...WITH WEAK FRONTAL BOUNDARY CLEARING
THE REGION SOMETIME ON THURSDAY. BELOW NORMAL TEMPERATURES
SUCCEEDING EARLY WEEK COLD FRONT WILL EDGE TOWARD AVERAGE VALUES
BY THURSDAY AND FRIDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1130 PM CDT FRI JUL 3 2015

MAINTAINED HAZE THROUGH THE OVERNIGHT FOR ALL BUT BJI. COULD SEE
SOME IMPROVEMENT TOWARDS MORNING BUT MORE LIKELY WILL BE MID
MORNING WHEN MIXING INCREASES. SOME POTENTIAL FOR SHRA/TSRA
TOMORROW AFTERNOON ACROSS EASTERN ND BUT COVERAGE LIKELY TO BE
SPOTTY SO LEFT OUT OF TAFS AT THIS POINT.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&

$$

SHORT TERM...TG
LONG TERM...WJB/TG
AVIATION...VOELKER



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