Area Forecast Discussion
Issued by NWS Aberdeen, SD

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419
FXUS63 KABR 231143 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
643 AM CDT Wed May 23 2018

.SHORT TERM...(Today and Tonight)
Issued at 410 AM CDT Wed May 23 2018

Fairly large complex of showers and thunderstorms continues to move
north-northeast within zone of convergence of the low level jet. A
few hours ago, there were wind gusts of 40 to 60 mph over parts of
south central SD, along with potentially marginal to sub-severe
hail. A handful of SPS`s have been issued over the past few hours to
cover this, but radar trends recently have showed weakening while
the main complex of precipitation still seems to be holding
together. Noting new development across the northern FSD CWA getting
ready to move into the southeast CWA. Have been adjusting POPs over
the past several hours to match radar trends and expected movement
of this complex over the next several hours. Look for this first
batch of showers and storms to eventually dissipate later this
morning.

Will then be watching how warm temps get today as breezy/gusty south
winds develop and we see even warmer air at 925/850 mb compared to
yesterday. If we`re able to get rid of morning convective debris
clouds early enough, we should be able to warm well into the upper
80s and low 90s across the region. Dewpoints will be a bit higher
today as well, with most areas well into the 60s. Therefore, it will
feel rather muggy. Increased wind speeds today closer to raw MAV
numbers instead of blended guidance, which seemed too low given the
good gradient and decent uni-directional wind speeds from the
surface up through 850 mb. Should be able to have good mixing today.

Focus then shifts to convection chances late this afternoon and
through the overnight. Moderate instability develops across the area
today. Strong afternoon heating may be able to erode the cap in
place and bring some widely scattered afternoon thunderstorms across
the area, but it appears the higher concentration of storms will be
across western SD into the NE panhandle where better deep layer
shear will exist and also where the surface trough sets up. CAM
solutions seem to suggest this, with varying degrees of areal
coverage of afternoon/early evening "heat of the day" storms over
the CWA, but a higher coverage farther west. As the storms out west
move east, an increasing low level jet once again in the
evening/overnight hours should allow an eastward propagation of some
form of a thunderstorm complex into the western CWA or even as far
east as the James Valley. Could see a strong wind threat with
whatever MCS develops eastward into central SD this evening.

.LONG TERM...(Thursday through Tuesday)
Issued at 410 AM CDT Wed May 23 2018

An upper ridge will continue to transition east on Thursday as an
upper trough approaches. A sfc low moving off the Rockies and
shortwave activity ejecting out ahead of the upper trough will keep
showers and thunderstorms in the forecast through Thursday night,
mainly across the east.

Conditions are expected to remain very warm next weekend as another
upper ridge builds in on Saturday. High temps will max out in the
90s, about 15 to 20 degrees above climo norms. Models have started
to show shortwave energy ejecting out of a deep western CONUS
trough. Coupled with another lee side low, there could be enough
instability to generate thunderstorms both Sat night and Sun night.
The upper trough will slowly move east through the early part of
next week keeping showers and thunderstorms in the forecast.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday Morning)
Issued at 641 AM CDT Wed May 23 2018

VFR conditions will prevail through the period. However, there
will be a few rounds of showers and thunderstorms set to affect
the taf sites this morning and then again overnight. Conditions
may deteriorate to IFR/MVFR in stronger storms.

&&

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

$$

SHORT TERM...TMT
LONG TERM...Wise
AVIATION...Wise



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