Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 211520 AAC

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1020 AM CDT Mon Sep 21 2020

Issued at 1019 AM CDT Mon Sep 21 2020

Current forecast is on track, therefore no changes made at this

UPDATE Issued at 704 AM CDT Mon Sep 21 2020

Made a few changes to the grids/forecast due to radiation fog
early this morning over the James River valley. The fog should
dissipate by mid morning.


.SHORT TERM...(Today through Tuesday Afternoon)
Issued at 347 AM CDT Mon Sep 21 2020

The short term looks rather inactive. A sfc boundary will remain
splayed mainly to the east and south of the CWA through tonight,
with any activity likely to occur nearer that boundary, per what
tnt`s CAM solutions indicate. On Tuesday, the front will start to
return north as a warm front with some increase in LLM and also
instability. However, a quick glance at soundings late Tuesday
afternoon continues to show, overall, a quite dry troposphere across
the region. So, the dry forecast should work out just fine.
Temperatures over the next couple days will be quite warm for the
time of year. Afternoon LL lapse rates should turn dry adiabatic
both today and Tuesday, which should lead to fairly deep mixing. And
according to the HRRR model, smoke shouldn`t be much of an issue.
So, how warm will we get? After looking over various LL thermal
progs/guidance, it appears it will be just a touch cooler today vs
Sunday, but then a bit warmer again for Tuesday. Overall, didn`t
stray too far from model blend.

.LONG TERM...(Tuesday Evening through Sunday)
Issued at 347 AM CDT Mon Sep 21 2020

Mild conditions, for late September, will continue into the
extended, with lows in the mid to upper 50s Tuesday night (~10 F
above normal). A shortwave is forecast to track across the Northern
Plains Wednesday, but it will have a difficult time yielding any
precipitation this far south. A sfc low will be in the presence of
an EML and 500 to maybe 1000 j/kg of CAPE by Wednesday afternoon
across the CWA, but forcing likely won`t be strong enough to
initiate showers/storms (>20 POPs are currently well northeast into
ND/MN). The warm air aloft should help promote very mild
temperatures however, with highs in the upper 70s to mid 80s. A low-
amplitude ridge aloft builds in for Thursday, keeping the area
largely dry and mild.

A bit of a change appears to develop from Friday into the weekend,
as an upper trough slides in from the Pacific Northwest. Per NAEFS
Percentiles, the most anomalously warm air aloft (850/700mb) passes
through Thursday night, but another mild day should develop Friday
prior to the eventual cold frontal passage. In addition to cooler
air for the weekend, with high temperatures near or below average,
this feature will bring the potential for precipitation. Details
about this, as well as the pattern that follows, are difficult to
pin down at this time.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning)
Issued at 618 AM CDT Mon Sep 21 2020


Other than some patchy fog around KABR/KATY early this morning,
VFR skies/vsbys are expected regionwide today and tonight.

***Construction to improve taxiways at both KABR/KPIR terminals
may cause an occasional temporary visibility reduction due
to blowing dust (bldu), mainly during daytime hours UFN.




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