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000
FXUS63 KABR 150718
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
218 AM CDT Mon Apr 15 2024

.KEY MESSAGES...

- Mild day today, with increasing southeast winds (peaking around
  40mph). Low afternoon humidity (20-25%) will warrant issuance of a
  red flag warning for much of the CWA.

- Low pressure will generate strong storms up into western/south
  central SD... just about up to the edge of the forecast area. Any
  storms that cross into the CWA come with mainly a risk of
  hail/winds, though storms will be moving into a less favorable
  environment for severe weather as they proceed into central South
  Dakota.

- Winds and precipitation will continue as the system crosses the
  region Tonight through Wednesday. Rainfall totals on the order of a
  half inch to an inch and a half.

- Cooler temperatures, around 10 to 15 degrees below normal, can be
  expected for the latter half of the week.

&&

.SHORT TERM /TODAY THROUGH TUESDAY AFTERNOON/...
Issued at 217 AM CDT Mon Apr 15 2024

Forecast focus is on fire weather conditions initially, shifting to
a severe weather threat followed by an assessment of rainfall QPF
for Tuesday.

Initially we are seeing high pressure to the northeast with a lee
low developing in Wyoming. The gradient at 12Z should be around 12-
14mb with 1/2km winds around 30-40kts. Through the day this gradient
continues to increase, peaking around 20mb from SW to NE across
SD...and will re-orient as a low over Nebraska becomes the dominant
feature. The time period of relevance however, will be during
daylight hours since we are concerned mainly with fire weather, with
CAM ensemble 25th/75th range for sustained winds/gusts is on the
order of 25 to 30kts and 35 to 40kts respectively...though there is
a period tonight where these winds peak around 45 to 50kts in spots.
So the real question is how warm and how dry for today. CAM
ensembles 25th/75th spread for highs is about 5 degrees so that is
the level of uncertainty we are dealing with...probably owing to the
fact that there will be some degree of cloud cover (mainly mid/high
clouds) influencing daytime heating.  Since we have been
overachieving of late with this dry pattern, will go a little above
the NBM. So what about dewpoints and afternoon humidity? Again there
is still quite a bit of spread (about 6 degrees) with several CAMS
showing lingering upper 20 dewpoints even into the afternoon despite
some higher humidity air eventually advecting into the CWA. With the
afternoon humidity at right around 20-25 percent and the strong
sustained winds/gusts...will upgrade much of the area to a red flag
warning.

Thunderstorm chances increase from the southwest part of the state
this afternoon/evening. While we will see some weak elevated
convection across the area earlier, coverage/intensity prior to the
arrival of the stronger storms will have limited influence on any
fire weather conditions, though it may potentially add a bit of
chaos to the winds. CAMS bring in convection towards Jones/Lyman
counties around 00Z, however thereafter the instability drops off
and BUFKIT profiles suggest convection will remain elevated as it
lifts into the CWA. Thereafter its more of a transition to
widespread rain/shower activity that will close out the short term
period. As for total moisture, the CAM ensemble mean is a bit lower
compared to the NBM mean...but given the convective nature of this
batch of moisture for most of its duration, there is inherently
going to be a wide range of outcomes across the CWA.

&&

.LONG TERM /TUESDAY EVENING THROUGH SUNDAY/...
Issued at 217 AM CDT Mon Apr 15 2024

On the backside of the system we will still be seeing some moisture,
with those gradient winds. Cold advection will enhance winds as
well. Cooler air follows, but its really late Wednesday before we
see the surge of really much colder air. This cold airmass persists
through the weekend, with 850mb temperatures down around a standard
deviation below climo. Should be relatively dry under this follow-on
high pressure system at least.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1211 AM CDT Mon Apr 15 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions for all terminals, with increasing southeast winds
through the course of the TAF period. May be some VFR/high based
VCSH though the day but too limited a coverage for inclusion in
any TAF sites outside of KPIR.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning from 11 AM CDT /10 AM MDT/ this morning to 8 PM
     CDT /7 PM MDT/ this evening for SDZ003>006-009>011-015>023-
     033>037-045-048-051.

MN...None.
&&

$$

SHORT TERM...Connelly
LONG TERM...Connelly
AVIATION...Connelly