Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 230820

Area Forecast Discussion
National Weather Service Aberdeen SD
320 AM CDT Wed Aug 23 2017

.SHORT TERM...(Today through Thursday Night)
Issued at 319 AM CDT Wed Aug 23 2017

Northwesterly flow will linger aloft through the period. While the
center of the sfc high has shifted across E NE and KS, a ridge
remains in place across eastern SD and western MN. The other main
sfc feature of note is the lee trough across MT/eastern WY/eastern
CO. A few clouds have been able to develop mainly across our south
central counties, which should thin out and exit to the southeast
through the day. Expect the sfc high to slide east today and stretch
from MT/WI down through IA/MO, as a reinforcing high sinks in from
southern Canada. There is an increased concern of rain showers
sliding into northeastern SD and west central MN overnight tonight,
assisted by a shortwave trough swinging across northern and central
MN 00-09Z. The best chance of measurable rain would be across
central Traverse County to eastern Big Stone County.

Late Thursday night may bring about another small chance of mainly
showers to southeastern portions of the cwa, as the sfc trough
slides closer.

.LONG TERM...(Friday through Tuesday)
Issued at 319 AM CDT Wed Aug 23 2017

Will start with an upper wave gradually suppressing the upper ridge
overhead. While we see increasing low level flow south of an
inverted trough/warm front across the forecast area, upper flow will
remain weak. 850mb dewpoints increase to +12 to +15C, and this will
allow for surface dewpoints into the mid/upper 60s - aiding in
destabilizing the atmosphere to the tune of around 1500-2000 j/kg
MLCAPE. Raised POPs over blended guidance to around 40-60 percent.
The setup overnight into Saturday morning features additional
overnight convection potential with weak flow aloft and a low level
jet. The focus of this jet is oriented into the eastern CWA, with
MUCAPE mainly located west of the James valley.  Could be a heavy
rain signature in that weak westerly flow aloft and an east-west
warm front impinged upon by a south-southwest oriented low level jet
may result in training of convection. PWATS are just over 1.5
inches, though these numbers are probably a bit high as 850/700mb
flow shows a tenuous connection to deeper tropical moisture stalled
along the gulf coast.

A near saturated low level airmass remains across the east into the
day Saturday - with a departing shortwave, but zonal flow and some
weak embedded waves evident upstream. Low level flow is weak so it
will be difficult to scour out the moisture during the day - so will
continue to mention the chance for additional convection into the
day Saturday.

We will see some drier northerly flow for Sunday - with a slightly
cooler airmass out of Canada with a 1020mb high. This high continues
slowly south/southeast and will result in mild/dry conditions for
the first half of the work week.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday Night)
Issued at 1227 AM CDT Wed Aug 23 2017

VFR conditions for all terminals.




LONG TERM...Connelly
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