Area Forecast Discussion
Issued by NWS Grand Forks, ND

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000
FXUS63 KFGF 190849
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
349 AM CDT Wed Jul 19 2017

.SHORT TERM...(Today and tonight)
Issued at 348 AM CDT Wed Jul 19 2017

Shortwave energy moving east into North Dakota from Montana will be
the initial focus for thunderstorm chances this morning. Favorable
effective shear and moisture and modest instability reside in
western ND, in closer proximity to the surface low, allowing for
storm development early this morning. Expect initial isolated to
widely scattered storms to form in north central North Dakota,
gradually tracking east into the Devils Lake basin area and
northeast North Dakota early this morning. The CAMs indicate that a
few strong to severe thunderstorms are possible in this area with
the main threats being hail to one inch in diameter and gusts to 60
mph.

By mid to late morning, surface based instability will begin
development and the warm front will begin working north into the
southern Red River valley. Additional shower and storm development
in central North Dakota will gradually move into eastern North
Dakota. Many CAMs suggest this development will eventually collide
with warm front forcing in the central valley, yielding thunderstorm
activity strengthening into the strong to severe discrete cells and
eventually a complex of storms moving southeast through the southern
Red River valley in the afternoon. These discrete cells and complex
would have the strongest threats with hail up to 2 inches in
diameter, damaging gusts to 75 mph, and tornadoes possible. Heavy
rainfall is a notable concern as well with precipitable water values
maxing at 1.5 to 2.0 inches this afternoon, especially over areas in
west central MN that received several inches of rain recently.
Additionally, there is some potential for additional storm
development behind the main complex in the middle to late
afternoon in the central to southern Red River valley, but this is
very uncertain at this time.

.LONG TERM...(Thursday through Tuesday)
Issued at 348 AM CDT Wed Jul 19 2017

Thursday-Friday...Weak ridging within zonal flow will lead to a dry
day on Thursday with temperatures near to above normal values.
Return flow commences Thursday night with weak shortwaves possible.
For Thursday night, most guidance suggests axis of instability will
remain across western North Dakota and that any early morning
actiivty should be weakening as it enters eastern North Dakota.
Although details are still uncertain, the potential does exist for
strong to severe storms Friday afternoon/evening as the axis of
instability propagates over the region with strong deep layer shear
in place.

Saturday-Monday...A stronger upper level wave will propagate
southeast across Canada into the Great Lakes region. This will
spread a cooler and drier airmass into the region. A few showers
will be possible across northwst Minnesota Saturday afternoon. The
airmass behind this system will be much cooler, and ridging will
lead to below normal temperatures on Sunday and Monday (with dry
weather).

Tuesday...Most guidance is in agreement suggesting upper flow
becoming zonal with the next series of upper waves bringing shower
and thunderstorm chances.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1135 PM CDT Tue Jul 18 2017

Still a lot of uncertainty in regard to convective development
Wednesday. Lots of differences between the models in the area and
timing. Seems like models still show KFAR to have the highest
potential, with lesser for the other TAF sites. That said, some of
the high resolution models do show weaker convection further
north, which would affect the other TAF sites. Do not have a good
feel for when that would be, so have just added a VCTS mention by
late morning for most of them. Will hopefully get a better idea
with later TAF sets.


&&

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

$$

SHORT TERM...BP
LONG TERM...TG
AVIATION...TG



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