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480
FXUS63 KABR 121742 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1242 PM CDT Wed Jun 12 2024

.KEY MESSAGES...

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- There are slight chances to chances (15-45%) of showers and
  thunderstorms through tonight. The precipitation chances this
  afternoon look to remain along and east of the James River
  Valley and mainly east of I-29. Some storms may become strong to
  severe.

- High temperatures today are forecast to warm into the upper 80s
  to mid 90s, which is 10 to 15 degrees above normal.

- A storm system Friday night through Saturday night and early Sunday
  will bring a 30-60% chance of showers and thunderstorms. The
  storm system may produce locally heavy rainfall over eastern SD
  and western MN.
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&&

.UPDATE...
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Issued at 1236 PM CDT Wed Jun 12 2024

See below for an aviation forecast discussion for the 18Z TAFs.

UPDATE Issued at 948 AM CDT Wed Jun 12 2024

Going forecast is doing fine. Made a couple refinements to the
PoPs to account for the precipitation working into the western
forecast zones. No other changes made to the forecast at this
time. Should see 90+F degree high temperatures over much of the
CWA today out ahead of the cold front that is currently positioned
over the western Dakotas. Updates are out.
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&&

.SHORT TERM /TODAY THROUGH THURSDAY AFTERNOON/...
Issued at 453 AM CDT Wed Jun 12 2024

Showers and general thunderstorms have developed early this
morning on the nose of a llj. Over the next few hours, sfc and
850mb winds are expected to become more southwesterly with
westerly winds aloft. That direction lends itself more to drying,
downslope winds rather than moisture converging, convection
developing flow, so will need to see if that cuts off some of
this activity. But, either way, all of the precip is expected to
exit to the east later this morning.

Models then diverge considerably from each other for this afternoon
and evening. Most do not have any further convective development
over this cwa. A couple, including the NAMNest and the ARW, have a
few storms developing either in west central MN or in Deuel county
between 22z and 0z before quickly exiting. SPC`s expansive slight
risk seems overdone to the west given these solutions. There is a
corridor of 3000 to 4000 J/kg of CAPE on models like the RAP with
45 kts of bulk shear along and east of the Coteau, so if any
supercells do form, they would produce large hail and strong
winds. Confidence is low on late afternoon development.

A weak baroclinic zone sets up tonight, though some guidance keeps
it farther south while others have it as far north as ND. Still,
added in some pops for tonight, though precip will have to overcome
the mid level dry air that is also moving in on westerly flow.

&&

.LONG TERM /THURSDAY EVENING THROUGH TUESDAY/...
Issued at 453 AM CDT Wed Jun 12 2024

The long term portion of the forecast begins on Thursday night with
a surface high pressure over the region with an upper level ridge
building over the northern Rockies. A deep upper level trough over
the desert southwest will begin lifting northeast by Friday morning
with perhaps some return flow developing over the Black Hills of
South Dakota. A weak shortwave crossing the area Friday afternoon
may cause convective developed over western South Dakota with the
convection spreading eastward Friday night through Saturday. An
increasing 30-40 knot LLJ, as well as upper level support for an
upper level trough should cause more robust convection Saturday
morning, mainly over eastern South Dakota and western Minnesota. The
NBM maintains a 20-35% chance of one inch of QPF over a 24 hour
period ending at 0Z Sunday. Eastern and especially southeastern SD
has the best potential of seeing moderate rainfall. Convection from
this initial round of storms should push east of the CWA Saturday
morning with a period of dry conditions possible Saturday through
Sunday.

However, an upper level trough and surface low pressure system
crossing North Dakota Saturday night into Sunday may produce
convection along the ND/SD border. Warm 700 mb temps of +12C may
limit the thunderstorm potential. Beyond Sunday, the weather pattern
remains active with two additional low pressure systems crossing the
region, bring more showers and thunderstorms early next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
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Issued at 1236 PM CDT Wed Jun 12 2024

Terminals KABR,KATY,KPIR,KMBG

Outside of thunderstorms, VFR conditions are forecast to prevail
at all four terminals through the TAF valid period. A shower or
thunderstorm may impact KATY terminal airspace between 18Z and 21Z
this afternoon. Any strong/severe thunderstorms are not expected
over far northeast South Dakota until later after 21Z. KATY holds
the highest probability (and it`s still rather low, at that) of
experiencing an early evening thunderstorm, as a cold front pushes
through and switches the wind there to a northwest direction. Once
timing/location of P.M. convection becomes clearer, will
introduce some -shra/-tsra mention into the KATY terminal (and
KABR, if need be) later this afternoon/evening as appropriate.
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&&

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

$$

UPDATE...Dorn
SHORT TERM...Wise
LONG TERM...SD
AVIATION...Dorn