FXUS63 KABR 191545 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1045 AM CDT Tue May 19 2026

.KEY MESSAGES...

- Frost/Freeze expected tonight/Wednesday morning (28 to 33
  degrees) between the Missouri valley region east into the 
  Sisseton hills region. 

- Another round of moisture, mainly Friday. Lower and upper 
  range for moisture is just a few hundredths to a 1/2 inch. 

- Turning warmer late weekend/early next week, about 10 to 20  
  degrees above normal (Highs: 80s to near 90).

&&

.UPDATE...
Issued at 1018 AM CDT Tue May 19 2026

Radar shows a few echoes across the CWA under some of these
lower level stratocumulus clouds. Sprinkles are already in the
forecast so not much for changes there. Temperatures will be
cool today with highs mostly in the 50s. Will make a few minor
changes to sky cover grids to account for satellite trends.
Otherwise, main story will be the frost/freeze conditions
tonight and will cover more of that for the afternoon forecast
package.

&&

.DISCUSSION...
Issued at 130 AM CDT Tue May 19 2026

Will leave the frost advisory in place though temperatures still in 
the low 40s/upper 30s with cloud cover and mid/upper 30 dewpoints, 
and northwest winds gusting to 15 to 20 mph making frost highly 
unlikely expect in the most protected/drainage prone areas.

Focus for freeze conditions continues tonight with high pressure 
shifted a little east in comparison to previous forecasts, centered 
over the Sisseton hills region. This still makes us ground zero for 
a frost/freeze. From the Missouri river and north of highway 14 NBM 
temperatures are still down around 30F. NBM upper bound (90th) even 
has lows in the low/mid 30s so at a minimum a frost. And the NBM has 
been consistent, leaving little doubt that the area will experience 
these cold temperatures and related impacts.

Additionally, daytime heating still showing up in NAM/GFS/RRFS 
BUFKIT profiles with shallow CAPE between 2 to 3kft up to about 
6kft. Cloud cover dissipates with loss of daytime heating. Evening 
temperatures are only expected to top mid 50s. Did bring back the 
mention of sprinkles as well. 

Aside from frost, some evidence for fog under the high given recent 
moisture and cool temperatures/lack of mixing. 

Focus shifts to additional rain chances late Thursday through Friday 
with southwest flow and then a negatively tilted shortwave. After 
that flow becomes more zonal and then another trough sets up out 
west for early next week. This flow regime results in milder 
temperature trends with NAEFS 850mb temperatures increase to a 
standard deviation above climo. NBM highs Sun-Tues some 10 to 20F 
above climo, though starting Friday the NBM 25th/75th range in 
temperatures begins to expand to 7 to 10 degrees suggesting lower 
confidence.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 620 AM CDT Tue May 19 2026

Terminals KABR,KATY,KPIR,KMBG

VFR to MVFR ceilings remain over the area, with pockets of
clearing. This is resulting in larger TEMPO groups for the first
few hours. Expect VFR ceilings at all locations by around 19Z,
holding out longest at ATY.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Freeze Warning from 11 PM this evening to 8 AM CDT Wednesday 
     for SDZ004>011-016>023-034>037-051.
MN...None.

&&

$$

UPDATE...TMT
DISCUSSION...07
AVIATION...06