Office: BIS
FXUS63 KBIS 170855
AFDBIS
AREA FORECAST DISCUSSION
National Weather Service Bismarck ND
355 AM CDT Wed Aug 17 2022
.SHORT TERM...(Today and Tonight)
Issued at 355 AM CDT Wed Aug 17 2022
Presently, upper level high pressure resides over most of the
western half of the CONUS resulting in a broad and somewhat lowly
amplified ridge. The forecast area remains under the eastern
extent of associated thermal ridge. At the surface, weak low
pressure presently located over southern Saskatchewan is helping
to generate isolated showers that have worked into the
northwestern corner of the state over the past few hours.
Through the period, the ridge will narrow and amplify over the
west CONUS as a potent trough slides down the eastern edge through
the forecast area. The expectation is that this will generate a
round of showers and thunderstorms this afternoon followed by
another tonight. Coverage appears somewhat widespread with perhaps
a best estimate that around half the forecast area could see a
wetting rain (.1 inch or more). Locations most likely to see a
wetting rain will be northern and especially central and eastern
ND.
Generally weak thunderstorms are expected as the atmosphere
stabilizes throughout the afternoon, while weak shear remains in
place over the most unstable areas, and mid-level lapse rates
remain marginal. The resulting skinny CAPE profile suggests this
could be another day where storms briefly pulse to strong, if not
marginally severe, before collapsing. In all, if a severe storm or
two was to occur, they would probably be limited to brief quarter
sized hail and isolated wind gusts up to 60 mph.
.LONG TERM...(Thursday through Monday)
Issued at 355 AM CDT Wed Aug 17 2022
Cutoff low pressure develops over the Corn Belt in the wake of the
aforementioned potent trough cutting through the area. This will
result in continued precipitation chances along and east of
Highway 83 through Friday. The further east one goes, the better
chance they have of seeing showers and thunderstorms Thursday and
Friday, along with a greater chance of seeing a wetting rain.
Once the system kicks out further east, conditions look to dry
out for most of the remainder of the extended.
Thursday through Saturday will see below average temperatures on
the order of around 5 to 10 degrees for this time of year. Areas
in the southwest will be closest to average, while areas further
north and east will be the coolest. This is especially true in the
southern James River Valley of ND, where rain and lingering cloud
cover is likely to persist the longest. Towards the end of the
weekend and into early next week, early indications are that a
thermal ridge over the west CONUS will work towards the area. This
will bring temperatures back closer to average, especially in
western ND. NBM MaxT ensemble 25th to 75th percentile spread is
generally on the order of 5 to 7 degrees to start next week. This
suggests moderate confidence in the day 5 to 7 highs.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday Night)
Issued at 1232 AM CDT Wed Aug 17 2022
Showers and weak thunderstorms are expected to impact the area
from west to east through the day Wednesday. Other than during any
showers or thunderstorms, VFR ceilings and visibilities, along
with light winds, will prevail.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Telken
LONG TERM...Telken
AVIATION...Telken
Office: FGF
FXUS63 KFGF 170830
AFDFGF
Area Forecast Discussion
National Weather Service Grand Forks ND
330 AM CDT Wed Aug 17 2022
.SHORT TERM...(Today through Thursday)
Issued at 321 AM CDT Wed Aug 17 2022
A couple of lingering shower/t-storm clusters remain in SE ND
having drifted south-southeast from the Cooperstown area and are
now in the Lisbon ND area at 08z. 50 dbz cores are much lower attm
and threat for small hail has diminished. Unsure how long this
elevated shower/t-storm stuff will linger but I think it should be
done by 13z. One other small area is in Clearwater county MN and
this has been drifting south too.
For the upcoming day Wednesday, the weak boundary separating a
very light and variable wind pattern to the north to a more
south-southwest wind to the south may hold in place. MUCAPES today
1500-2300 j/kg range north to south. But upper levels there isnt
going to be much around as the 500 mb trough axis shifts a bit
more east. Therefore for now when a dry fcst for most of the day.
Late day could see isolated activity in central MN and also some
activity ahead of our next 500 mb system moving into central
Saskatchewan may move in the DVL basin. Chances for
showers/t-storms will increase tonight as 500 mb wave moves east-
southeast to SE Saskatchean. To the south and southeast of the
wave will be cluster of thunderstorms. Severe weather is not
anticipated.
Thursday will see the 500 mb wave combine with a wave dropping
more south thru western Manitoba and stronger 500 mb low will
develop over the Red River valley by 00z Friday. Therefore do look
for increased chances/coverage of general showers and
thunderstorms Thursday.
.LONG TERM...(Thursday night through Tuesday)
Issued at 321 AM CDT Wed Aug 17 2022
BOTTOM LINE UP FRONT...
Heavy rainfall appears to be an increasing threat through Friday. A
rather moist airmass coupled with repeated shots of precipitation
will bring some much needed rainfall to the region. Generally a few
tenths to an inch are expected through Friday, although areas that
receive heavier thunderstorms will see higher totals.
METEOROLOGICAL ANALYSIS...
Our friendly upper low is rotating over Alberta/Saskatchewan and
looks pretty spinny for a lack of better words. This feature is
being handled pretty well by ensemble guidance, so at a minimum
there is high confidence in timing and amplitude of the wave. Expect
this wave to begin to pivot and dive south over the next few days
bringing multiple shots for precipitation.
Within this upper low, a rather moist airmass sits over us. PWAT
values are ranging in the 1.4-1.6" range with this upper low. While
not earth shattering by any stretch of the imagination, it is still
a rather moist airmass. Combining this with rather strong lift, the
potential for solid rainfall with this system appears increasingly
likely.
There does appear to be a rather marginal potential for some flash
flooding threat to arise. However, confidence is very low in this
arising. The ingredients appear there for potential isolated flash
flooding issues, as forecast soundings indicate moist adiabatic
lapse rates across much of the troposphere combined with very low
corfidi vectors. However, with the limited instability field, it
seems like it will be tied heavily to where thunderstorms fall, as
there is a significant lack of steering flow. This would be our
reasonable worst case scenario, however confidence in this scenario
arising is very low.
For the majority of the remaining long term period, the very weak
flow pattern is expected to persist across the area. Potential is
there for brief shots of showers and thunderstorms, mainly diurnally
driven, although confidence and predictability in impacts is low.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1127 PM CDT Tue Aug 16 2022
VFR conditions prevail through the TAF period, with patchy fog
possible around KGFK and KTVF. A stray shower or thunderstorm is
possible along a boundary that stretches from west to east across
the area. Winds remain light and variable through the period.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
$$
SHORT TERM...Riddle
LONG TERM...Perroux
AVIATION...Lynch
