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fxus63 kfgf 202026 

Area forecast discussion
National Weather Service Grand Forks ND
326 PM CDT Fri Sep 20 2019

Mesoscale discussion...
issued at 312 PM CDT Fri Sep 20 2019

Ongoing convective activity from this morning, continues to slowly
push eastward as we head through the afternoon with marginally
severe storms remaining possible.

Our next complex of storms will impact the region later this
afternoon into the evening hours as a cold front moves through the
area. Ahead of the front, mixing ratios of 12.5 to 13.5 g/kg and dew
points in the middle to upper 60s will enhance instability.
Effective layer bulk shear is expected to be in the 40 to 45 knot
range ahead of the Theta-E boundary, giving US a chance for either
embedded supercells or supercell/multicell cluster hybrid-Mode
storms initially early this afternoon. Progression into linear Mode
will be rapid, possibly occuring prior to moving into the County Warning Area.

MLCAPE levels will top out just below 4000 j/kg, thus plenty of
instability remains available heading into this evening. The best
chance for severe thunderstorms will occur in the Devils Lake basin
from around 5pm Onward through about 7pm, progressing eastward into
the Red River valley from about 7pm Onward. Risks will include large
hail, especially for the Devils Lake basin, damaging wind gusts, and
possibly tornadoes (along a possible qlcs), possibly pushing into
northwestern Minnesota before midnight.


Short term...(this evening through saturday)
issued at 312 PM CDT Fri Sep 20 2019

High confidence in slow moving storm complex to impact the
northern half of the area tonight with the severe potential
mentioned in the mesoscale discussion. With precipitable waters greater than
1.5 inches and abr/bis soundings indicating 150 to 200 percent
above normal values storms will be very efficient rainfall
makers. Given these conditions and the slow moving forcing from
the upper low and embedded short wave will see a line of storms
train as they propagate slowly east southeast this evening into
the overnight. This results in a widespread 1 to 3 inches of
rainfall possible across the northern half of the forecast area with an inch
or less for areas along and south of I-94 through the noon hour

With the upper low slowly lifting northeast across southern
Manitoba and westerly wind shift or cold front pushing across the
forecast area tomorrow morning into the afternoon will see storm coverage
increase early in the afternoon Saturday with another round of
storms possible. Some storms could become severe with wind gusts
to 60mph and hail up to an inch in northwest Minnesota.

Long term...(saturday night through friday)
issued at 312 PM CDT Fri Sep 20 2019

Sunday and Monday...upper level trough currently over southern
Idaho will move into Ontario by 12z sun. Wrap around precip over the
northeast zones will move north and east out of the area sun.
Short wavelength ridge will move across the Red River valley Mon.
Quiescent weather is expected Mon.

Tue - Fri

Long wave trough over central Canada and the northern plains will
shift into Hudson Bay. Long wave ridge over the eastern Pacific will
build north into the Gulf of Alaska. Downstream long wave trough will
dig into the West Coast. Long wave ridge over the southeast US
builds farther north into the mid Atlantic states. Southwest flow
aloft develops over the northern plains by Fri.

The operational models have a cutoff low over the Desert Southwest
will get kicked out to the northern plains on Fri as another trough
will drop into the Desert Southwest. GFS and European model (ecmwf) ensemble mean
precip agree reasonably well for next Fri. The European model (ecmwf) and GFS
operational models are in good agreement through Wed. The GFS
becomes the faster model thereafter.


Aviation...(for the 18z tafs through 18z Saturday afternoon)
issued at 1235 PM CDT Fri Sep 20 2019

Winds and storms will be the major impact over the taf period.
Warm front near tvf will continue to bring thunder to the area for
the early afternoon. South winds will continue to gust to around
25kts in the valley this afternoon into the evening. As line of
storms develops to the west it will move into the dvl area around
00z and then gfk in the 02 to 04z time frame based on the latest
guidance. A line of storms will gradually move east overnight.
Westerly winds will develop tomorrow with gusts in the 20 to 25kt
range again. MVFR cigs may develop overnight behind the storms and
would linger into the late morning hours.


Fgf watches/warnings/advisories...


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