Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 211518 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1018 AM CDT Sun May 21 2017

.UPDATE...
Issued at 1012 AM CDT Sun May 21 2017

An area of low pressure over eastern MN will continue producing
cloudy skies and light drizzle in the eastern half of this CWA.
With the cloudy skies, temperatures along and east of the I-29
corridor will only warm into the upper 40s to the lower 50s. Have
lowered temps down a few degrees in east. Further west, CAMS
suggest showers developing late this afternoon. These showers
could reach the Missouri River valley before dissipating.

&&

.SHORT TERM...(Today through Tuesday Afternoon)
Issued at 422 AM CDT Sun May 21 2017

Today: Light returns continue in wrap around that extends across the
James valley while to the east, its more drizzle than actual
rainfall. Also have seen a few pockets of snow mixed in but no
accumulation. CAMS suggest as the low continues to migrate away from
the CWA, precipitation will wane, however clouds will be slow to
erode with GFS off and on saturated at the 500/700mb levels. NAM
profiles also suggest some daytime heating will translate into
strato-cumulus. Thus expect much of the eastern CWA will struggle to
warm past 60, while farther west will see better insolation and
highs in the 60s.

Tonight: The pressure gradient will continue to relax with a weak
inverted ridge over the eastern CWA. Given the cool start, any gaps
in mid/high clouds will allow temperatures to plummet thanks to the
light winds. Thus, added mention of frost across mainly eastern
counties. Farther west, mid level moisture associated with the
secondary wave pinwheeling around the upper low to the east should
limit the temperature drop. Additionally, given the recent moisture
and potential for clearing - also added patchy fog to the forecast.

Monday: Secondary wave pivoting across the Dakotas will support
shower activity. For most of the area precluded mention of thunder
with a mid level inversion/skinny cape limiting the intensity of
convection within hail growth region, with most of the CAPE below
10kft. Steep mid/low level lapse rates will also allow for gusty
northwest winds.

Tuesday: We will see the cool low level airmass become transformed
by diabatic heating, resulting in shallow convection. At only a few
hundred feet in depth according to NAM soundings - don`t expect much
for QPF - just deep enough to generate sprinkles. This also means
temperatures will continue to struggle to surpass 60F.

.LONG TERM...(Tuesday Evening through Saturday)
Issued at 422 AM CDT Sun May 21 2017

A mid level trough and associated shortwave energy will the on the
way out of the region Tuesday night, with ridging setting up
Wednesday and Thursday. A low will become nearly stationary over
central Canada Friday and Saturday, with southwest flow and periods
or shortwave energy affecting the Northern Plains Friday and
Saturday.

Surface high pressure will dominate the pattern Tuesday night
through the day Wednesday. The high gets pushed east Wednesday night
by an approaching low pressure system and associated frontal
boundary. This system will become reinforced over the central part
of the country as one low remains over Canada and another develops
to the south, keeping a somewhat active pattern in place Friday and
Saturday. Will keep the pops fairly low for the time being to allow
for fine tuning as the time period gets closer.

Temperatures will be mild through the period, with highs mainly in
the 70s. After a cool night with lows in the lower 40s Tuesday
night, lows in the upper 40s to the lower 50s will be common.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday Morning)
Issued at 628 AM CDT Sun May 21 2017

IFR/MVFR cigs will remain over the far eastern CWA this morning,
before lifting to VFR levels in the afternoon. The remainder of
the area will see VFR conditions, with just a few light rain
showers lingering across the north central CWA early this morning.
By mid to late afternoon, VFR conditions will then prevail across
the entire area through the TAF period.


&&

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

$$

UPDATE...SD
SHORT TERM...Connelly
LONG TERM...Parkin
AVIATION...Parkin


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