Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 271753
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
1253 PM CDT Tue Jun 27 2017

.UPDATE...
Issued at 1237 PM CDT Tue Jun 27 2017

Temperatures in our northeast CWA are not warming as expected with
several locations in the low to mid 70s. Thick, high level clouds
is keeping temps from warming in this area. The threat for strong
to severe storms still looks good for tonight, mainly in south
central SD and along the ND, SD border. The NAM model suites are
showing the best convection occurring in Nebraska with a limited
coverage in this CWA. Other models suggest the cap will hold in
Nebraska with convection occurring along the ND, SD border.
Damaging winds and large hail will be the main hazards with any
thunderstorms. With high PWATS, brief periods of heavy rain will
also be possible.

&&

.SHORT TERM...(Today through Thursday Afternoon)
Issued at 417 AM CDT Tue Jun 27 2017

First off, we will see strong southerly winds today as a 16-18mb
pressure gradient develops across the Dakotas. Additionally,
pressure falls of 8-9mb in 6 hours are noted across the area. This
will push us close to advisory level winds, with sustained winds
around 30mph, though gusts will probably fall shy of 45 mph
except for all but the more exposed areas. This is also
responsible for high fire danger conditions today.

These strong winds proceed a front and upper wave, and will draw
somewhat higher humidity into the region, with a narrow ribbon of
850mb dewpoints increasing to +12 to +14C by 00Z, which
translates into dewpoints in the upper 50s to low 60s Fahrenheit.
700mb temperatures increase to +10 to +12C, which will cap the
atmosphere for today, though there may be some weak elevated
convection through the afternoon, which is depicted in a handful
of CAMs. As the cold front moves into the western CWA and towards
the Missouri valley between 00 and 03Z, it will be the focus for
surface based convection, with the core of 700mb warm air moving
off to the east. Low level turning is evident in NAM BUFKIT
profiles, but winds aloft are not very strong, and 0-6km shear
around 50kts is probably dominated by this strong low level flow.
CAPE ranges between 1500-3000 J/kg, so the threat for supercells
and tornadoes exists, although LCL of 4kft initially is a tad high
in my taste. CAMS generally support the transition of storms east
across the CWA between 02-08Z. During this time, a low level jet
with 1/2km winds of 40-50kts will develop. This may enhance low
level turning ahead of the front before storms transition to
elevated convection with a stronger wind/hail threat.

.LONG TERM...(Thursday Evening through Monday)
Issued at 417 AM CDT Tue Jun 27 2017

An upper level trough will be over the central part of the country
at the beginning of the extended period, with a series of shortwaves
set to track across the region Thursday night through Saturday
before the trough exits to the east and northwest flow becomes
dominant.

At the surface, broad weak low pressure will be over the Northern
Plains early in the period. With the upper shortwaves moving through
during this time, may see some shower and thunderstorm activity
Thursday night and Friday before high pressure settles in over the
region, bringing dry conditions back for the early part of the
weekend. Another low pressure system looks to track somewhere across
the central plains region on Sunday and Monday, bringing unsettled
conditions and precipitation chances back to the area.

Below normal temperatures will be the rule early on, with highs in
the 70s Friday and Saturday. Will then see a gradual warming trend
with highs back up in the 80s Sunday and Monday. Overnight lows will
be mainly in the 50s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 1237 PM CDT Tue Jun 27 2017

VFR conditions will prevail through this evening. A strong area of
low pressure will cross the region late this afternoon and through
the overnight hours. Winds ahead of the surface low will be gusty
from the south with sustained winds in the 20 mph range. Winds
will shift to the west then northwest behind the surface low.
Strong to severe thunderstorms will be possible as the low crosses
the region. Some storms could produce damaging winds and large
hail. Flying conditions will change drastically for any terminal
that experience a thunderstorm tonight.

&&

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

$$

UPDATE...SD
SHORT TERM...Connelly
LONG TERM...Parkin
AVIATION...SD



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