438
FXUS63 KABR 041522 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1022 AM CDT Thu Jul 4 2024

.KEY MESSAGES...

- Below normal/cool temperatures, spotty rain showers and a few weak
thunderstorms will persist across the area through the day today.

- There is a 20% chance of mainly afternoon showers and weak
thunderstorms Friday.

- The active weather pattern of showers and thunderstorms will
persist into the weekend, mainly focused over eastern SD into west
central MN with around a 50% chance of showers and
thunderstorms Saturday afternoon and Sunday afternoon.

&&

.UPDATE...
Issued at 1016 AM CDT Thu Jul 4 2024

No major changes to the going forecast. The low pressure system
responsible for morning showers and thunderstorms continues to
rotate around the region. Widespread coverage should reduce to
isolated coverage this evening. Lightning is the main hazard with
any thunderstorms today.

&&

.SHORT TERM /TODAY THROUGH FRIDAY AFTERNOON/...
Issued at 418 AM CDT Thu Jul 4 2024

The surface weather map shows low pressure over eastern
ND/northwestern MN and eastern SD, with a large area of high
pressure set up from western MT through much of WY. The area of low
pressure will focus over western MN by 21Z this afternoon, before
shifting to southeastern MN/western WI by 06Z Friday.

Normal high temperatures for the 4th of July are in the low to
mid 80s. Cool and humid conditions are expected today, with highs in
the upper 60s and low 70s, or 10 to near 15 degrees below normal.
Relative humidity values today will remain above 50 percent. While
some short term CAMs do indicate the potential for low clouds, they
are more scattered that originally expected.

While severe weather is not anticipated today, a few thunderstorms
will remain possible. With significant outdoor activities planned
for today, the potential of lightning has been highlighted in the
Hazardous Weather Outlook. We`ve also continued a lightning safety
graphic on our webpage and social media accounts for folks to seek
shelter in a building or hard-topped vehicle when lightning is
around. Limited thunderstorms are expected, but can`t be ruled out
today with our CAPE values below 500 J/kg (highest over eastern
SD/western MN this afternoon). A more spotty/scattered look to the
showers and thunderstorms is expected, ending west to east this
evening as the surface low continues to exit east. Dry weather will
return late tonight.

3-hourly flash flood guidance is below 2 inches for portions of the
Missouri River valley from roughly Mobridge and Selby and Hovel,
southwest through Stanley County and northwestern Jones County.
Precipitable Water values range from near 1" from our southwesterly
counties to closer to 1.3" over eastern SD and west central MN
through the day, which is in the 50th to 75th percentile (or near to
slightly above normal for this day climatologically) based on the
SPC sounding climatology page. Plenty of moisture will be around,
with a few stronger/more persistent showers or thunderstorms able to
produce rainfall amounts of around 1" this afternoon.

A 20 percent chance of afternoon showers and thunderstorms will
return Friday afternoon, well behind the surface low over MI as a
ridge of high pressure builds into western SD.

&&

.LONG TERM /FRIDAY EVENING THROUGH WEDNESDAY/...
Issued at 418 AM CDT Thu Jul 4 2024

Friday evening we are between systems as a low moves off to our east
and a low/shortwave moves in from the west. Models vary a bit on
what is going to happen over the weekend. The EC and Canadian have a
shortwave move across the Dakotas Saturday and then have a weak
low/strong shortwave come through Sunday lasting through Monday
night. The NAM (through the end of its run) and the GFS have a low
move across ND with the trough stretching south into SD through
Sunday night. There is no second low/shortwave with these second two
models. Then we stay in north to northwesterly flow aloft through
the end of the period.

While showers and storms are possible Friday evening through early
Monday morning, accumulations are expected to be less than half an
inch. NBM shows chances of more than a quarter of an inch in 72
hours (ending Monday morning) to be around 50% for areas along and
east of the James River and less to the west. The best chances are
Saturday evening into early Sunday morning with 30-55% PoPs (highest
mainly east of the James River). Otherwise, chances max out around
30%. After Monday, chances for rain are minimal.

Saturday and Sunday look to be the coolest days of the period with
highs in the mid 70s to around 80. This is 5 to 10 degrees below
normal. The rest of the period is expected to be around normal.
Winds for the most part will be relatively calm with gusts only
reaching 25 mph for a few hours Sunday and again on Thursday west
river, and maybe reaching 20 mph to the east.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 717 AM CDT Thu Jul 4 2024

Terminals KABR,KATY,KPIR,KMBG

Showers have started to fill in across central and eastern SD by
12Z, with showers becoming more predominant in the TAFs through
much of the daytime hours. While thunderstorms will remain
possible, they are more scattered in coverage. VFR to MVFR
conditions are expected through the period, down to MVFR in more
moderate rain and with lower clouds moving to ATY around daybreak
Friday.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

UPDATE...Serr
SHORT TERM...KF
LONG TERM...KK
AVIATION...KF