Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 222345
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
645 PM CDT Fri Sep 22 2017

.UPDATE...
Issued at 645 PM CDT Fri Sep 22 2017

Elevated convection increased in coverage from Stutsman into
Foster Counties late this afternoon, on the nose of the strongest
mid-level warm air advection centered near 850 mb per RAP-based
guidance. That forcing is expected to be the primary driver of
precipitation through the evening and so we refined PoPs slightly
accordingly with this update, focusing on that area northward
toward Rolla. Earlier brief subsidence in the wake of what
appeared to be an eastward-propagating gravity wave per
preliminary, non-operational GOES-16 visible satellite imagery
has shifted eastward. The exit of that mesoscale subsidence also
likely contributed to the convection, but the warm air advection
is also forecast to refocus eastward by mid evening and so that
will cause precipitation chances to dwindle until after 06 UTC,
when another vorticity maximum embedded in southwest flow aloft
will reach southern ND. Some recent HRRR simulations suggest a
strong storm could affect Dickey and LaMoure Counties with that
wave late tonight, where MUCAPE will likely still be sufficient
for isolated stronger, elevated updrafts.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 139 PM CDT Fri Sep 22 2017

Scattered showers and thunderstorms will continue through the
evening hours for most of western and central North Dakota. Later
tonight precipitation shifts south and east as the surface trough
swings into Minnesota. With ample elevated instability, shear and
a low freezing level, several storms could produce marginally
severe hail this afternoon and evening. A very cool night is in
store with northerly winds and temperatures in the 30s and low
40s for most.

.LONG TERM...(Saturday night through Friday)
Issued at 139 PM CDT Fri Sep 22 2017

The main focus for the Long term will be cooler temperatures with
a good chance for showers Saturday and Sunday. The cool weather
will last at least through next Tuesday. Highs during this period
will be in the 50s and lows in the mid 30s to mid 40s. There could
be some patchy frost during this period. Chances for showers will
continue through Tuesday until the upper trough finally moves
through. Then moderating temperatures at least into the 60s are
expected with mainly dry weather for Wednesday and Thursday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 645 PM CDT Fri Sep 22 2017

A mix of VFR ceilings over the northwest half of the state and
MVFR to local IFR conditions in far southwest and south central
ND as of 23 UTC is expected to transition to widespread MVFR and
local IFR ceilings in stratus tonight and Saturday morning.
Showers and a few thunderstorms are possible tonight, mainly in
south central ND and the James River valley. A more widespread
area of rain is expected to develop in southwest ND Saturday
afternoon.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...CJS
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...CJS



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