Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 221719 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1219 PM CDT SUN MAY 22 2016

.UPDATE...
Issued at 1025 AM CDT SUN MAY 22 2016

Showers and thunderstorms are ongoing this morning just east of
the James River valley. These waa storms should continue tracking
northeast through the early afternoon hours. Temps at 700 mb are
warming to +8C behind the storms...which should limit convection
over the western CWA through at least 21Z. Some of the latest
models are suggesting the the cold front/dry line will slide
across the far western CWA as early as 0Z. That said...still
believe convection is best in this CWA closer to 3Z and after.

UPDATE Issued at 657 AM CDT SUN MAY 22 2016

12z aviation discussion updated below.

&&

.SHORT TERM...(Today through Tuesday Afternoon)
Issued at 356 AM CDT SUN MAY 22 2016

Main focus will be the today period as the atmosphere continues
to appear primed for severe thunderstorms. Model trends remain
fairly consistent, primarily the slow down of the surface front,
which is now expected to drift into our west river counties this
afternoon. The other noticeable model trend is that the NAM has
continued to bring in much higher dewpoint airmass, ramping up
MLCAPE values into the 3000j/kg range. prefer the GFS 2000j/kg
starting point. A +9C 700mb airmass is moving over the area this
morning, and remaining over the eastern CWA this afternoon. Cooling
at 700mb this afternoon west river will occur ahead of a weak
southwest flow shortwave. The shear environment is mainly
unidirectional with 0-6KM bulk shear values between 30 and 40kts.
Now for the caveats, there is a broad expanse of stratus located
under widespread cirrus which will cut down on heating. High res
models starting to hint at this with mainly spotty/weak/elevated
convection possible just about anywhere across the cwa through much
of the day thanks to that 700mb plume of warmer air, however there
isn`t much consistency with convective development through 00Z
within the location of the front. CAM solutions point to an evening
0-3Z depiction of stronger cell development, suggesting that the low
level jet will play a larger role in convective initiation and
maintenance.

Storms motion is expected to be north/northeast at 30 to 40kts,
however being tied to the front could result in training of storms
overnight. The low level jet lingers across the eastern CWA well
into Monday morning, with redevelopment during the afternoon likely
to be just along the eastern extreme of the cwa before storms move
off into Minnesota. Westerly low level flow will result in dry
conditions for most of the CWA, with deep mixing allowing for
readings in upper 70s/low 80s both Monday and Tuesday. With
southwest flow aloft persisting, we could see some additional mid
level convection associated with a pair of weak waves, late Monday
and again late Tuesday.

.LONG TERM...(Tuesday Evening through Saturday)
Issued at 356 AM CDT SUN MAY 22 2016

The models remain consistent and agree well in the long term with
the upper level flow pattern. Our region remains under southwest
flow aloft from Tuesday Night through Saturday. The period starts
out with a small upper level low pressure area off the CA coast. A
couple short wave troughs will come over our region before this low
pressure area kicks out and northeast into our region. The models
then show a large upper level low pressure area dropping into the
western U.S. Thursday night into Saturday. Therefore...the short
waves around this upper low will eject out and across our region
into Saturday. As a result of all of these short waves...chances of
showers and storms will continue through the entire long term
period. Temperatures through the period will be near to slightly
above normal and mostly in the 70s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday Afternoon)
Issued at 1217 PM CDT SUN MAY 22 2016

A mix of vfr/vfr conditions are expected through the rest of
today and tonight as a front moves east over the region. Sct
shra/tsra are expected to form again over western SD this
afternoon and evening then move east overnight. Gusty winds and
low vsby can be expected with thunderstorms.

&&

.ABR Watches/Warnings/Advisories...
SD...NONE.
MN...NONE.
&&

$$

UPDATE...SD
SHORT TERM...Connelly
LONG TERM...Mohr
AVIATION...TDK


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