Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 171722 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1222 PM CDT Mon Apr 17 2017

.UPDATE...
Issued at 1212 PM CDT Mon Apr 17 2017

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

UPDATE Issued at 1135 AM CDT Mon Apr 17 2017

Nudged high temps up a degree everywhere but the far eastern
zones. Made a few modifications to afternoon/night-time dewpoints
as well as minor timing adjustments to weather/pop grids based off
the latest HRRR/RAP13 and local WRF trends. Updates are out.

UPDATE Issued at 626 AM CDT Mon Apr 17 2017

See updated aviation discussion below.

&&

.SHORT TERM...(Today through Wednesday Afternoon)
Issued at 304 AM CDT Mon Apr 17 2017

High pressure will slide over Minnesota today setting up an easterly
flow over eastern SD this afternoon. Temps will warm into the upper
60s in the southwest to mid 50s in the northeast. Today will remain
dry.

The main forecast focus is the system tonight. Models are all in
pretty good agreement with bringing a potent fast moving shortwave
across the Dakotas overnight. The jet energy associated with this
wave is impressive, in excess of 80 knots as the front exit region
moves across northern SD. As expected, the EC and GFS are pretty
aggressive with developing convection, but the NAM is more on the
dry side, but still has development. Taking a close look at
stability, the NAM does indicate a very narrow ribbon of moisture
and instability with Most Unstable Cape (MUCAPE) of around 1100
J/KG. However, this cape is not showing up in the bufkit
soundings, perhaps indicating how narrow and short lived this cape
will be before mixing out and convection forming due to strong
jet and warm air advection. Taking a look at the mesoscale models,
all are showing various degrees of convection, with most
indicating a linear cluster moving across the east before exiting
around 12z. 03z-12z looks like the timing of the system as it
moves through. SPC has region under general thunderstorms, but
can`t rule out a few hail storms as the dynamics are pretty
impressive. Storms will be elevated.

Tuesday will remain dry until the next system arrives in the
southwest flow. Pattern looks active with the Monday night and
Wednesday pacific systems taking aim for our region, bringing in
better chances of rain. Wednesday system looks more stratiform in
nature as well.

.LONG TERM...(Wednesday Evening through Sunday)
Issued at 304 AM CDT Mon Apr 17 2017

A mid level shortwave trough over the Northern Plains Wednesday
evening will push off to the east during the overnight hours. Will
then see a brief period of ridging before another shortwave
approaches and tracks across the Central Plains Friday and Saturday.
Most of the energy associated with this trough will remain south of
the region. Ridging develops again on Sunday.

At the surface, low pressure will extend from New Mexico to southern
Iowa Wednesday evening, with precipitation ongoing to the north of
it, including over the ABR CWA. The precipitation will come to an
end overnight as high pressure drops in and pushes the system off to
the east. Much of the remainder of the extended period will be dry,
but cannot rule out a few showers here and there, especially Friday
night into Saturday as a low pressure system tracks across the
Central Plains. Some minor differences in the models on the track of
this, so should it take a more northerly shift, there could be some
precipitation over this area. For now, will keep pops fairly low
since it is still several days out. Instability is virtually non-
existent as well, so will keep precipitation mention throughout the
period as rain. High pressure will bring dry conditions on Sunday.

Temperatures will be right around normal through the period, with
highs mainly in the 60s and lows in the 30s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
Issued at 1212 PM CDT Mon Apr 17 2017

VFR conditions will prevail across the area through this evening.
Showers and thunderstorms will track from west to east across the
region tonight, and cigs and vsbys may briefly fall to MVFR or
worse in heavier/stronger thunderstorms. By Tuesday afternoon,
current guidance showcases prevailing VFR returning.

&&

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

$$

UPDATE...Dorn
SHORT TERM...Scarlett
LONG TERM...Parkin
AVIATION...Dorn



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