501
FXUS63 KABR 121000
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
500 AM CDT Mon May 12 2025

.KEY MESSAGES...

- An extended stretch of hot, dry, and windy conditions will persist
through Tuesday. Temperatures will break the 90 degree mark at many
locations, which is at or near record highs.

- Fire danger will remain elevated to critical through Tuesday for
much of the forecast area with southerly winds gusting 35 to near 50
mph. A Red Flag Warning remains in effect through this evening.

- Thunderstorms are expected Tuesday night through Thursday morning
with highest chances (50 to 70%) Wednesday.

&&

.DISCUSSION...
Issued at 457 AM CDT Mon May 12 2025

Deep southerly flow continues to be maintained early this morning
across our local region as high pressure at the sfc and aloft
remains in a fairly consistent position across the Great Lakes while
lee of the Rockies sfc troughing persists, which is part of a larger
southwest flow regime aloft as an upper trough/low is currently
entering the picture in parts of the Pacific Northwest. The upper
level ridging across the Great Lakes is being squeezed back to the
west so to speak as an upper low churns it way from the Deep South
into the Ohio Valley. This ridging will more or less continue to
keep the dry pattern going through most of this period, but it will
be gradually breaking down over time as the aforementioned PacNW
upper trough digs into the Great Basin the next couple of days.

Hot, windy and dry will continue to be the main themes in this
period today through Tuesday night. Daytime highs will again easily
make it to 90 degrees or better for most locales today as +20C to
+25C 850mb temps are maintained. In fact, new record highs will
likely be achieved as record values for May 12th are only in the
upper 80s to low 90s. NBM wind gust probabilities of 25+ mph for
today once again look solid for most of the area from the Missouri
Valley east into western Minnesota where values range from 75% to
nearly 100%. The exception is our far western zones(north central
SD) where probabilities fall to 40-60%. As noted on Sunday, the
strong winds kicked up and transported areas of blowing dust into
parts of our forecast area reducing visibilities. As conditions
remain unchanged today, we may see a repeat of this especially in
areas where field work is taking place or areas where topsoil has
recently been turned over and remains loose. As temperatures quickly
climb by midday and afternoon into the 80s and 90s under these windy
conditions, RH values fall once again between 15-20% across the
entire CWA. Therefore, the Red Flag Warning will remain in place
through early this evening. RH`s do begin to recover by late evening
but remain below 40% until early Tuesday morning, so we may have to
determine during the daytime hours today if this headline needs to
be extended out further in time.

Tuesday will be sort of a rinse and repeat scenario as not much
change is expected from what we`ve experienced already the last
couple days. There will be a sfc low pressure system and associated
cold front that will track into the western Dakotas during the day
and perhaps make into our far western zones by late afternoon. NBM
wind probs of 25+ mph drop even farther to 30-50% along and west of
the Missouri River Tuesday afternoon. Farther east, another gusty
day is expected as probs of 25+ mph range from 80-100%. One element
worth tracking on Tuesday will be sfc dew point temperatures.
Guidance has been suggesting on some low level moisture recovery to
be maintained for a longer period of time through the afternoon with
values in the 40s to low 50s. However, with daytime temperatures in
the 90s for most locales, this puts our afternoon RH values into the
15-25% category again. We`ll have to consider additional fire
weather headlines for Tuesday if the conditions warrant.

As an upper-level trough to the west of SD moves towards the east
Tuesday evening into Wednesday morning, a surface low pressure sets
up over CO/NE and stretches up into western SD. On the west side of
this low pressure, the models develop a line of precipitation, though
the models vary the location and timing of this precipitation. Most
models have this line setting up over western into north central SD,
while other models keep the precipitation out of central SD. The
precipitation then start to spread over central and eastern SD
Wednesday afternoon into the evening as a cold front moves through
the state. The models vary the location and timing of the surface
low pressure moving out of SD which then causes there to be
differences with the precipitation around the low moving out of the
state. The precipitation will be out of SD during the day Friday.

There is a 20-50% chance for thunderstorms Wednesday as the cold
frontal boundary moves through central and eastern SD Wednesday
afternoon, with a 20-30% chance for storms late Tuesday evening into
Wednesday morning over north central SD. The SPC has put a majority
of central and eastern SD in a marginal (1 of 5) risk for severe
storms to pop up as that cold front moves through. While the CAP
will likely erodes through the day Wednesday, it will likely be on
of the hurdles the storms will need to overcome to become severe.
One hazard to mention is the potential amount of rainfall from the
precipitation moving through Wednesday into Friday. The clusters
currently have a 30-50% chance for greater than an inch of QPF to
happen east of the Missouri River by Friday afternoon. However,
there is still variability in the models as to where the line of
heaviest precipitation will move through and how much is will drop.

Wednesday afternoon southerly winds will increase over the James
River Valley, with gust over 30kts. Then behind the cold frontal
passage, northwesterly winds will increase west of the James River
Thursday, with some areas seeing gusts over 35kts. These stronger
winds stay around and spread east through Friday before dying back
after that. With mid-level having cold air moving into central and
eastern SD after the cold frontal passage, temperatures will start
to drop, becoming 5-15 degrees colder than normal Thursday through
Saturday. High temperatures during this time look to get into the
upper 50s to upper 60s.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1234 AM CDT Mon May 12 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast through the TAF period. Low-level wind
shear (LLWS) will remain a concern through the overnight hours for
all TAF sites. Strong and gusty southerly surface winds will
continue on Monday.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning until 9 PM CDT /8 PM MDT/ this evening for
     SDZ003>011-015>023-033>037-045-048-051.

MN...Red Flag Warning until 9 PM CDT this evening for MNZ039-046.

&&

$$

DISCUSSION...Vipond/12
AVIATION...TMT