Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 101958

Area Forecast Discussion
National Weather Service Grand Forks ND
258 PM CDT Mon Aug 10 2020

.SHORT TERM...(This evening through Tuesday night)
Issued at 256 PM CDT Mon Aug 10 2020

Quiet weather prevails today, with nearly zonal flow aloft.
Temperatures are on track to reach the middle to upper 70s under
clear skies. Breezy west to southwest winds are expected to continue
through the mid to late afternoon, then diminish this evening.

Dry weather is expected to continue through Tuesday, with
thunderstorm chances returning as we head through the overnight
hours. An upper low begins to deepen across eastern British Colombia
and western Alberta late Tuesday afternoon; this will serve to
amplify the overall flow pattern heading into mid-week.

.LONG TERM...(Wednesday through Monday)
Issued at 256 PM CDT Mon Aug 10 2020

For the Wednesday through Sunday time frame, look for an more active
pattern marked by higher temperatures and humidity and strong to
severe thunderstorm chances. Weather relate impacts are possible
Wednesday and Thursday in association with thunderstorm activity.

Looking at Wednesday, thunderstorm chances increase ahead of an
approaching shortwave and associated cold front. Southeasterly
surface flow will being increasing moisture values into the area,
with dew points expected to approach the upper 60s to low 70s from
the Red River Valley westward. This will facilitate CAPE values in
the 3000 to 3500 J/Kg range, with good ensemble support from both
the GEFS and ECMWF suite. Low level shear in the 0 to 1 km and 0 to
3 km layers will be at or slightly greater than 20 knots
referencing the latest GFS soundings. The main question surrounds
the temporal element of initiation and whether or not it occurs
during peak heating. The better forcing is expected during the
very late afternoon into the evening and overnight; however, there
remains a non-trivial amount of disagreement between ensemble
members, thus introducing an element of uncertainty. As for severe
potential, there will be at least a chance for isolated to
scattered strong to severe thunderstorms during the late evening
and early overnight period.

Heading into Thursday, ongoing embedded thunderstorm activity could
delay any potential activity later Thursday afternoon. Ensemble CAPE
values display a larger degree of disagreement for Thursday, with a
range from 2500 to 4000 J/Kg depending upon which suite we are
referencing. Shear will be rather dismal in the 0 to 6 km layer,
with good low level shear in the 0 to 1 and 0 to 3 km layers.
Although convective activity could begin late in the evening once
more, the severe chances for Thursday look environmentally
favorable. Forcing will be provided along another transient
shortwave along increasingly southwesterly H5 flow.

Friday through Sunday: A cold front will push through the region
late friday afternoon, with another chance for thunderstorms along
and ahead of the front. We could see another day of potentially
strong thunderstorm, although timing and strength this far out
remains uncertain. Much quieter post-frontal conditions prevail
Saturday with some remnant shower and thunderstorm activity
lingering through the morning. Otherwise, look for quiet weather
late Saturday through Sunday.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1216 PM CDT Mon Aug 10 2020

VFR conditions prevail at all TAF sites through the afternoon and
evening hours. West to southwest winds are expected to remain
gusty through the afternoon, with gusts upwards of 28 kt for sites
within the Red River Valley and westward. These winds will
diminish late this afternoon, with speeds of 10 kt or less going
into tonight.



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