752
FXUS63 KABR 151147 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
647 AM CDT Mon Jul 15 2024

.KEY MESSAGES...

- Showers and thunderstorms possible late tonight through Tuesday
with precipitation chances ranging from 20 to 50 percent, highest
over central SD. The threat for severe weather will be isolated with
a Marginal Risk (1/5) over central SD. The main threat will be 60
mph wind gusts and up to quarter sized hail.

- Below normal temperatures in the 70s to low 80s are anticipated
Tuesday and Wednesday. Temperatures may be able to recover to
something closer to normal Thursday onward.

&&

.UPDATE...
Issued at 635 AM CDT Mon Jul 15 2024

See below for an aviation forecast discussion for the 12Z TAFs.

&&

.SHORT TERM /TODAY THROUGH TUESDAY AFTERNOON/...
Issued at 250 AM CDT Mon Jul 15 2024

As of 230AM an MCS is moving east/southeast across eastern ND into
MN with a broken line of storms from this moving over our
northeastern CWA. We still could see isolated storms behind the MCS
through the morning with pops of 15-20%. The shortwave will continue
to push east/northeast as HREF indicates the axis of the wave from
northwest MN through northeastern SD by 12Z this morning. Winds
behind this wave will be zonal and turning northwesterly as a ridge
amplifies over the western CONUS/western Canada with the Northern
Plains in between this ridge and a large low moving in over Ontario
with shortwave energy continuing over the Northern Plains. Within
the 850mb trough, the center of the surface low will be over
~central SD with a surface trough extending southward from here,
with much of the northern and northeastern CWA behind the cold front
by 12Z morning. Through the morning into early afternoon, this front
will continue to sink south with a high pressure system behind it,
keeping the area quiet through the day. A broad area of low pressure
exists from southern SD and northwestward into MT tonight into
Tuesday.

With this setup, NBM does a good job indicating moisture moving in
from MT/ND and pushing southeast with pops of 20-40% between 06-12Z
Tuesday, mainly around and west of the Mo River. Additional moisture
moves in over much of the CWA Tuesday with pops ranging from 30-50%
between 12Z Tuesday-00Z Wed. CAMs do indicate this, however, still
dealing with timing and location differences. With the cooler air
mass, dew points will range in the upper 50s to the lower 60s
through Tuesday. Instability is less with MUCAPE, across central SD,
only up to 1000 J/KG and dropping off farther east, however, shear
will be between 30-40kts tonight with lapse rates around 7 in
central SD. So if we have any severe weather it would be very
isolated overnight. Tuesday afternoon and evening instability
increases to around 1000j/kg over south central SD with HREF UH>75
showing a few paintballs in this area, indicating organized
convection. So again, isolated severe storms possible.

With the cooler air behind the front, 850mb temps this afternoon
will range from 14-21C with surface highs in the 80s, with upper 80
readings across south central SD. Even cooler for Tuesday with 850mb
temps 13-19C across the CWA with highs ranging in the 70s to the
lower 80s.

&&

.LONG TERM /TUESDAY EVENING THROUGH SUNDAY/...
Issued at 250 AM CDT Mon Jul 15 2024

Clusters and deterministic progs maintain a western CONUS upper
level ridge throughout the period of varying degrees of magnitude.
But, it appears that the "heat dome" associated with it never quite
makes it as far as this CWA (at least not through Sunday). ECMWF
S.A. ensemble table output for 850hpa is gradually coming down, and
is now between zero and one (or more) standard deviation(s) below
normal from Tuesday of this week through Tuesday of next week. So,
at this point, be looking for a healthy dose of upper 70s to upper
80s for high temperatures in the offing.

As for precipitation chances, in-house PoPs guidance is doing its
summer climo thing over many of the extended forecast periods, while
the CWA sits within either northwest or north flow aloft. Not saying
shortwaves can`t move southeast or south through the region in these
types of set-ups. Just saying they are tough to "see" and time, and
they are not often able to sample a meaningful low to mid-level
moisture source to efficiently produce more then sprinkles to about
a tenth of an inch of rainfall, whenever it does rain. So, be
thinking generally a dry or mostly dry forecast in the out periods
(Tuesday night through Sunday).

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 635 AM CDT Mon Jul 15 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast through tonight. There could be some
occasional sprinkles or very light rain showers this morning, but
most of the TAF valid period should be dry. The next shot at
widespread shower activity shows up on Tuesday, just beyond the
scope of the currently valid TAFs.

&&

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

$$

UPDATE...Dorn
SHORT TERM...MMM
LONG TERM...Dorn
AVIATION...Dorn