Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 111119 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
619 AM CDT Fri Aug 11 2017

.SHORT TERM...(Today through Sunday Afternoon)
Issued at 356 AM CDT Fri Aug 11 2017

High pressure overhead this morning resulting in some isolated areas
of fog, while to the northwest we can see a weak wave drifting
southeast. Models show this feature will shear apart through the
course of the day, and likely have little impact on the forecast
other than some remnant/isolated mid cloud cover. Otherwise, high
pressure centers to the east, with a weak lee low to the west
resulting in light southerly flow, with only an 8mb gradient
across the state. There may also be some shallow cumulus as
evident in GFS/NAM BUFKIT soundings. To the west of the CWA,
several CAMS support surface based thunderstorm activity. Most
keep convection west of the CWA through 00Z, after which we may
see some remnants stagger across the western border before
dissipating with loss of daytime heating.

Overnight, the next shortwave comes in from the northwest, with mid
level isentropic ascent. Despite increasing shear, CAPE values are
negligible thanks to mainly moist adiabatic mid level profiles.
Thus, anticipate scattered weak/elevated shower activity.

Saturday will feature the slow moving shortwave across the western
Dakotas. Low level isentropic upglide is mainly focused west river,
where profiles become more supportive of surface based convection
with upwards of 1000 j/kg MLCAPE, with CAPE values falling off
rapidly eastwards - where the precipitation mode is more associated
with another weak surge of isentropic ascent. Thus, any severe
weather threat is focused along and west of the Missouri valley. The
severe weather risk, while limited by low CAPE numbers, will be
supplemented by much stronger shear thanks to the tail end of a 60-
80kt jet, and about 40kts at 500mb. There is also a decent Q-vector
signature across the area Saturday afternoon, though it appears more
to the east and may favor enhancement of the broadscale area of
precipitation vs surface based convection to the west.

Storms weaken with loss of heating, however precipitation will
linger across the area as the 700mb reflection is slow to move east -
persisting well into Sunday across eastern counties.

.LONG TERM...(Sunday Evening through Thursday)
Issued at 356 AM CDT Fri Aug 11 2017

Upper ridging is expected to build over the Plains early next week
before becoming more zonal midweek. This will help push temperatures
back toward average values with highs in the 80s expected by
Tuesday. A number of shortwaves will move through the upper flow
through the week with a more potent sfc cold front slated for
Tuesday night and again Thursday night. These features will bring
chances for showers and thunderstorms.


.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 618 AM CDT Fri Aug 11 2017

Patchy dense fog will affect northeastern SD early this morning
before the sun rises. This will cause KATY to fall to IFR vsby at
time. VFR conditions are expected through the remainder of the
peirod. Showers will begin to move into KMBG and KPIR after




SHORT TERM...Connelly
AVIATION...Wise is the U.S. government's official web portal to all federal, state and local government web resources and services.