Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 241756
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
1256 PM CDT Thu May 24 2018

.UPDATE...
Issued at 1240 PM CDT Thu May 24 2018

See updated Aviation discussion below.

UPDATE Issued at 1042 AM CDT Thu May 24 2018

An environment increasingly suitable for thunderstorm development
is taking shape across eastern South Dakota and west central
Minnesota this morning. Thinning cloud cover and increasing
dewpoints into the 60s are increasing CAPE to around 1500 J/kg,
in the warm sector out ahead of a cold frontal boundary. The main
area of low pressure sits across far northeastern Montana, and
thus the better forcing resides further north. CAMs reflect this
idea, as only widely scattered storms are output across the CWA.
While only 30 or less kts of bulk shear is expected, steep low-
level lapse rates should help increase the chance for severe
weather - large hail and damaging winds - where storms do develop,
generally just west/along and then east of the James River Valley
this late afternoon/evening.

&&

.SHORT TERM...(Today and Tonight)
Issued at 349 AM CDT Thu May 24 2018

MCS from last evening has decayed across central SD and we are just
left with low-level jet-induced showers across the eastern CWA. Made
some adjustments to POPs to reflect current radar trends. It would
appear today that we will see less residual morning
convection/showers compared to yesterday. Therefore, feel clouds
will be a bit thinner through the morning with more sunshine
available to heat things up ahead of the approaching frontal
boundary. Will once again see breezy/gusty south winds along with
dewpoints rising through the 60s. Highs look to reach the upper 80s
to low 90s as the air mass out ahead of the front/dry line become
moderately unstable by afternoon. Will once again have the potential
to see afternoon showers and thunderstorms in the warm sector ahead
of the approaching boundary. Strong to severe storms are possible
based on parameters including adequate bulk shear values and mid-
level lapse rates. It would appear that the stronger forcing for
ascent in relation to the upper trough will be across ND. There is
some overlap in our CWA with the better mid-level lapse rates and
the moist axis.

.LONG TERM...(Friday through Wednesday)
Issued at 349 AM CDT Thu May 24 2018

A sfc trough will exit Friday morning leaving the region mostly dry.
The dominant feature through the weekend will be a building upper
ridge that will allow very warm temps to surge into the region.
Highs in the 90s are expected on Sat and Sun. Another lee side low
will develop by Sat evening. Coupled with some shortwave energy
ejecting out of an intermountain upper trough in the west, there
will be sufficient instability for some thunderstorm development
both Sat and Sun nights. The upper trough and the lee side low will
transition east into the Dakotas on Monday bringing further chances
for showers and thunderstorms all the way into Thursday. Some cooler
air will move into the Dakotas behind the low on Thursday with highs
falling back into the 70s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1240 PM CDT Thu May 24 2018

VFR conditions are expected through the period, the possible
exception being during thunderstorms if they manage to develop
over the ABR and/or ATY sites. Best chance for thunderstorms will
be this afternoon/evening.

&&

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

$$

UPDATE...Lueck
SHORT TERM...TMT
LONG TERM...Wise
AVIATION...Lueck


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