Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 181758 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1258 PM CDT THU AUG 18 2016

.UPDATE...
Issued at 1258 PM CDT THU AUG 18 2016

18z aviation discussion updated below.

UPDATE Issued at 949 AM CDT THU AUG 18 2016

Just some quick updates this morning to increase pops over the
eastern third of the CWA. Continue to monitor storms over northern
Roberts County, that have been producing 45mph winds and pea to
possibly dime sized hail. Minute by minute SRSOR data has been
very helpful, especially over central SD, showing the warming
aloft with the line extending towards PIR.

UPDATE Issued at 627 AM CDT THU AUG 18 2016

See updated aviation discussion below.

&&

.SHORT TERM...(Today through Saturday Afternoon)
Issued at 439 AM CDT THU AUG 18 2016

Have seen an uptick in thunderstorm activity across the area over
the past couple hours, especially in/near the James valley as low
level jet/warm air advection increases over the region. Have
adjusted POPs accordingly over the next couple hours to account for
a bit better coverage of storms over the James valley. Main focus
will be later today as the strong cold front pushes southeast across
the CWA. Rich low level moisture will be in place ahead of the front
with dewpoints in the 60s to around 70 degrees. Mid-level heights
will also begin to fall as the upper trough approaches. Moderate
instability will set up across the CWA today as the front moves
through. Quite a spread of solutions noted amongst the CAMs which
unfortunately leads to a fairly low confidence forecast regarding
where storms will set up today. This led to a rather broad-brushed
approach to POPs. Seems there could even be some post-frontal
convection where slightly better 0-6km bulk shear resides. Given all
the severe parameters, strong to severe storms are certainly
possible with large hail and strong winds being the main threats.
The main question though is areal coverage and placement of the
storms. One area models seem to be hitting at the most is the
eastern CWA into west central MN as current activity over ND
eventually makes its way southeast by later today.

After this activity moves out by this evening, focus will then be on
the much cooler temperatures moving in. Although, chances for
showers and storms will remain in the forecast. Highs Friday and
Saturday will only be in the upper 60s to low 70s with continued
chances for precipitation as the upper trough swings through the
Dakotas.

.LONG TERM...(Saturday Evening through Wednesday)
Issued at 439 AM CDT THU AUG 18 2016

An upper level trough will be centered over Minnesota when the
extended period begins, with northwest flow beginning to develop
over the CWA. This trough will slide east of the area by midday
Sunday, with the northwest flow then dominant until ridging builds
over the plains on Monday. Will see a shift to southwest flow on
Tuesday as the ridge pushes east and another trough approaches, with
a few weak shortwaves set to track across the area Tuesday and
Wednesday.

Surface high pressure will be over the area Saturday night and
Sunday, then pushes east with the area becoming situated between the
exiting high and approaching low pressure. The low and associated
frontal boundary will reach the area Tuesday night, becoming the
focus for shower and thunderstorm development. May see lingering
precipitation across the east into the day Wednesday as the front
slowly pushes east.

Temperatures will be a bit cool on Sunday under the surface high,
with highs mainly in the 70s. Will then see warmer air return with
highs in the 80s to lower 90s Monday and Tuesday, before the front
moves through and temps cool slightly, with highs mainly in the
lower to mid 80s on Wednesday. Overnight lows will be cool to start
the period, with 40s Saturday night and 50s Sunday night before a
return to lows in the 60s Monday night and Tuesday night.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1258 PM CDT THU AUG 18 2016

Other than some temporary mvfr ceilings early on at abr and aty,
expect mainly vfr conditions at all locations through tonight and
Friday morning. The main issue will be the scattered showers and
thunderstorms developing through the night as an upper level low
pressure trough drops in from the northwest. The stations are
expected to be affected with at least some showers and vicinity
thunder.

&&

.ABR Watches/Warnings/Advisories...
SD...NONE.
MN...NONE.
&&

$$

UPDATE...Mohr
SHORT TERM...TMT
LONG TERM...Parkin
AVIATION...Mohr



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