Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 250528 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1228 AM CDT Sun Jun 25 2017

.UPDATE...
Issued at 1224 AM CDT Sun Jun 25 2017

See updated aviation discussion below.


UPDATE Issued at 624 PM CDT Sat Jun 24 2017

Adjusted overnight temperatures at the borders a little lower than
previous. Increased cloud cover based on latest satellite imagery.
Models aren`t resolving the stratus shield moving down from ND
very well, but areas east of the Missouri River look like they
will be affected. While these clouds could have an impact on
overnight temperatures, there are some breaks in the stratus well
to the north and skies are expected to clear after midnight.

&&


.SHORT TERM...(This Evening through Sunday)
Issued at 254 PM CDT Sat Jun 24 2017

Forecast challenges include low temperatures tonight and
precipitation chances Sunday afternoon.

Currently, under a partly to mostly sunny sky, temperatures are
warming through the 60s and in some places into the 70s. Breezy to
windy northwest winds also continue throughout the region at this
time.

The unseasonably cold airmass in place throughout the region will
remain through Sunday, as steering winds aloft continue to direct
cool/dry high pressure southeastward out of Canada. Sunday morning
low temperatures could be flirting with record territory once again
in some spots (see PNSABR). Much will depend on how long cloudiness
sticks around over northeast South Dakota and west central MN and
where winds go light and variable/calm for the longest overnight.
Surface high pressure Sunday morning should be centered over the
Missouri River valley region.

Water vapor imagery reveals a couple shortwaves embedded within
the northwest flow pattern aloft over Alberta and southern
Saskatchewan that will likely be over this CWA by Sunday
afternoon, bringing some low end chances for rain showers/isolated
thunder. Augmented the previous shifts enhancements with latest
available hourly CAM output for afternoon pops coverage/timing.
Also, per deterministic and ensemble thermal progs, much below
normal (2 standard deviations) temperatures persist for Sunday
high temperatures again.


.LONG TERM...(Sunday Night through Saturday)
Issued at 254 PM CDT Sat Jun 24 2017

A 1026mb high pressure will move into the Dakotas early Monday
morning allowing for favorable radiational conditions yet again.
This high pressure slowly drifts southeast with return flow
developing by Tuesday. The gradient across the area increases with
about a 16-20mb gradient across the state, so again will increase
winds above blended guidance. GFS BUFKIT mixed winds are again
topping out in the 30-40kt range so close to advisory level.

While not a great fetch for gulf moisture, the GFS depicts a narrow
plume of higher 850mb dewpoints extending into the region, in part
thanks to those strong conveyor winds. Warming 700mb temperatures,
between +10 and +13C should result in capped conditions however. The
strong winds will decouple Tuesday night into a 50-60kt low level
jet. This is ahead of a shortwave, which has sped up slightly in the
12Z suite of model runs. The combination of these two features,
combined with cooling 700mb temperatures, will result in convective
instability, with strong low level shear, and the potential for
severe storms - although jet stream winds are only around 40kts.

The front clears our area early Wednesday so the potential for storms
drops off quickly. The upper flow is more zonal with the low
circulation just to our north, with several weak waves moving in
from the Pacific Northwest - and while not terribly unstable with
temperatures at/below average and low low level humidity - mid level
clouds and precipitation will provide additional chances for
moisture across the region late in the work week and for the
weekend.


&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday Night)
Issued at 1224 AM CDT Sun Jun 25 2017

VFR conditions are expected overnight and through the day Sunday.
Winds will continue to diminish overnight and become light and
variable for the western sites. As a shortwave moves through the
region on Sunday, isolated thunderstorms will be possible. Still
too uncertain on areal extent and timing to add a mention in the
TAFs, however.

&&


.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

UPDATE...Wise
SHORT TERM...Dorn
LONG TERM...Connelly
AVIATION...Parkin



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