Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 121126 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
626 AM CDT Sat Aug 12 2017

.SHORT TERM...(Today through Monday Afternoon)
Issued at 342 AM CDT Sat Aug 12 2017

We are already seeing scattered weak convection early this morning
associated with an initial spike in 700-600mb isentropic ascent.
This area of mid level showers will continue east this morning and
into the early afternoon. Additionally, a non-severe MCS west of
Bismarck is headed in the direction of the CWA and several CAMS
support this feature moving into the forecast area by late
morning/mid day.

We will also see an unstable atmosphere develop today ahead of the
shortwave in eastern Montana as well. Despite dewpoints only topping
out in the low 60s, 700mb temperatures are rather cool, between +3
and +7C or about a standard deviation below climo, resulting in
about 1500-2000j/kg MLCAPE across the western periphery of the CWA,
though with a rapid drop off to the east. 0-6kt shear across the
west is also around 40-50kts, though its important to note that
there is little wind below 600mb, and that most of the shear is due
to the 60-80kt jet stream overhead. Conditions west river do look
favorable for strong storms and thus SPC marginal/slight risk area -
with storm rotation and the main risk being hail and winds.

The weak low level jet redevelops again tonight, as the shortwave
moves southeast into the western Dakotas. Q-vectors point to
favorable dynamics aloft as well, with the main focus for model QPF
into eastern South Dakota. CAMS also transition between daytime
convection out west to more widespread light convection across the
east during the evening/early overnight hours. Slow overall motion
of this system and only about 20kts of winds below 20kft supports
slow cell motion so we expect a decent soaking under convection
overnight. PWATS are between 1 - 1.33 which is not
climatologically outside the norm however.

Sunday the wave continues slowly east, with isentropic analysis
suggesting precipitation organizing/intensifying along a warm
front across northeast counties, with a weak TROWAL like feature
extending back to the west into the James valley. Additionally,
GFS BUFKIT profiles are mainly moist adiabatic, so any daytime
heating will result in additional convection outside of the area
of isentropic forcing.

.LONG TERM...(Monday Evening through Friday)
Issued at 342 AM CDT Sat Aug 12 2017

Numerous shortwaves will move across the region through the week as
upper ridging translates back to upper troughing. Coupled with low
pressure at the sfc, expect showers and thunderstorms and an overall
wet pattern through the week with only brief breaks. Finally, by
Saturday high pressure will build in at the sfc and conditions will
dry out. Temperatures will remain a couple of degrees below average
next week with highs in the upper 70s east and mid 80s southcentral
most days.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday Morning)
Issued at 624 AM CDT Sat Aug 12 2017

VFR conditions are expected through this afternoon except in
heavier showers and thunderstorms when conditions may drop to IFR.
MVFR cigs will move into the region late tonight and linger
through Sunday morning.

&&

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

$$

SHORT TERM...Connelly
LONG TERM...Wise
AVIATION...Wise



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