Area Forecast Discussion
Issued by NWS Bismarck, ND

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753
FXUS63 KBIS 201405
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
905 AM CDT Sat May 20 2017

.UPDATE...
Issued at 901 AM CDT Sat May 20 2017

Large precipitation shield associated with the upper low moving
north into the eastern Dakotas this morning. Clouds filling in
northwest with the increasing moisture. Some breaks in the cloud
deck southwest. Current forecast trending ok with some minor
adjustment to lower cloud amount southwest today.

UPDATE Issued at 639 AM CDT Sat May 20 2017

Current forecast in good shape. Showers are beginning to encroach
upon southeast ND and should push into the far southeast forecast
area this morning. Removed the mention of frost for this morning.
Updated text products will be sent shortly.

&&

.SHORT TERM...(Today and tonight)
Issued at 202 AM CDT Sat May 20 2017

Main highlights in the short term period continue to be
frost/freeze highlights. Also precipitation chances over the far
south central into the James River Valley.

Current temperatures are mainly in the upper 30s and 40s, even
within the freeze warning. Will cancel the frost advisory and
freeze warning. A few areas could see some frost, but nothing
widespread is anticipated this morning.

An upper level low over the central plains will lift northeast
into the eastern Dakotas and Minnesota by 12 UTC Sunday. This will
bring a chance of showers to far south central ND into the James
River Valley this afternoon and tonight. Elsewhere, considerable
cloudiness will be the rule today with clearing across the west
and possibly into the central portion of the state late tonight.

For highs today we leaned toward a MOS based forecast with
temperatures a little warmer than yesterday in the west, about the
same north central and a little colder in the south central,
closer to the approaching upper low. We also utilized a blend of
the given short term guidance with a time lagged blend of the
RAP/HRRR to determine minimum humidities this afternoon. This
lowered them from the given guidance but did not drop off as
drastically as the HRRR/RAP did this afternoon. We then blended
our given guidance with MOS based winds to arrive at slightly
higher winds this afternoon.

Day shift will need to monitor for possible frost/freeze
highlights again tonight. MOS Guidance did not do a particularly
good job with lows this morning with the added moisture/cloud
cover. But if we do clear out in the west as forecast tonight, we
could again see lows in the middle and possibly even lower 30s.

.LONG TERM...(Sunday through Friday)
Issued at 202 AM CDT Sat May 20 2017

The upper level low that lifts into the northern plains tonight
will linger over the northern Great Lakes through early Tuesday.
This will keep a cyclonic upper level flow and a chance for
showers and isolated thunderstorms Sunday and Monday.

We did bump up winds over our given guidance both Sunday and
Monday. The surface gradient is not that impressive, especially on
Sunday, but a uni-directional northwest flow Sunday afternoon
should develop as we mix out with daytime heating. With weak
instability in the west Sunday afternoon, we could see a few
thunderstorms. If they do develop, would not be surprised to see
some gusty winds given the inverted V signature of the forecast
soundings. Monday winds are not uni-directional as high up into
the atmosphere as Sunday, but upper level winds are stronger and
the surface gradient is tighter. Not expecting windy conditions
either day, but breezy conditions can be expected each afternoon
with a few gusts into the 20-30 mph range.

Deterministic models are now in better agreement as we head into
the middle portion of the work week. The Western U.S. Ridge
Finally pushes the Great Lakes trough eastward, bringing a warm
and dry period over forecast area during the middle portion of
the work week. An upstream trough pushes the upper ridge south and
east of the area toward the end of the work week bringing a
little cooler weather with a more active flow bringing a daily
chance of showers and possibly a few thunderstorms.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 639 AM CDT Sat May 20 2017

Low pressure moving from the central plains into the Great Lakes
region will keep VFR clouds over the area with an easterly flow
through the day today. Added a VCSH this morning at KJMS and then
showers this afternoon. Both short term models and MOS guidance
are pointing towards MVFR to possible IFR ceiling at KJMS tonight
as low pressure approaches. Added a period of MVFR VSBYS and
ceilings beginning at 03 UTC Sunday. Surface flow generally east
today 15 mph or less. Flow becomes light tonight and switches to
the west over western TAF sites toward the end of the period.


&&

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

$$

UPDATE...WAA
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...TWH



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