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000
FXUS63 KABR 151540 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1040 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.

&&

.UPDATE...
Issued at 1032 AM CDT Mon Apr 15 2024

The overall trend of morning showers diminishing by mid-day/early
afternoon, then dry with a mix of sun and clouds until evening
convection develops/moves north into the CWA still works. Gridded
forecast database reflects this, so no changes planned to the
today period forecast at this time. As far as strong to severe
convection potential, still wanting to keep a close eye on how
the boundary layer changes over time, between ~23Z and 05Z, down
across Jones/Lyman counties, as that is where a northward moving
warm front will be encroaching during said time. Deep layer/low
level shear and instability appear to potentially trend up
notably this evening across south central South Dakota.

&&

.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 /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 611 AM CDT Mon Apr 15 2024

Terminals KABR,KATY,KPIR,KMBG

We`re starting out with VFR conditions this morning. Aviation
concerns will increase through the morning and into the overnight
hours as winds increase out of the southeast to east with gusts
30-40kts. Light showers over central SD could bring a few rumbles
of thunder to MBG and/or PIR this morning. Low level wind shear
returns at nearly all locations around 04-12Z Tuesday.

&&

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

MN...None.
&&

$$

UPDATE...Dorn
SHORT TERM...Connelly
LONG TERM...Connelly
AVIATION...KF