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358
FXUS63 KBIS 251734
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1234 PM CDT Sun Jun 25 2017

.UPDATE...
Issued at 1219 PM CDT Sun Jun 25 2017

This update focused on showers and temperatures. Band of light to
moderate rain showers extended from Dunn County east/southeast near
Washburn/New Salem towards Mandan/Bismarck/Wilton and east to much
of Kidder County/Steele and south across Napoleon/Wishek/Ashley
areas. Latest iterations of high res CAMs indicate this area of
showers will continue its movement southeastward. Looking at
forecast soundings, it is possible we may realize some CAPE and get
some isolated thunder thunder in some of the stronger cells, but
nothing severe. The CAMs are suggesting that by around 7pm we might
see some lingering showers in the James Valley near the SD border,
but for the most part shower activity should end by early evening.

Regarding temperatures, temps were cooler than forecast beneath
cloud cover in central ND, but a tad higher than forecast in hourly
obs in the far southwest. The backdoor cold front was draped across
southwestern ND with drier air and west/northwest winds evident from
eastern MT into far southwestern ND. Adjusted hourly temps with
current high res models with highs in the mid 70s far
southwest...and only reaching the mid to upper 60s north and east of
the Missouri River.

UPDATE Issued at 859 AM CDT Sun Jun 25 2017

This update will focus on the showers moving through west central
into central North Dakota. Updated POPs to likely across this
region this morning.

UPDATE Issued at 615 AM CDT Sun Jun 25 2017

Current band of showers has set up a little farther west than
forecast. RAP/HRRR have not completely caught on so made some
small manual adjustments after populating with a blend of the non
time lagged versions of the RAP/HRRR. Otherwise no significant
changes to the going forecast.

&&

.SHORT TERM...(Today and tonight)
Issued at 243 AM CDT Sun Jun 25 2017

Cool temperatures and shower activity highlight the short term
forecast period today.

CAMS continue to be persistent in bringing a band of showers from
northwest through south central ND today. A shortwave currently
over southern Saskatchewan will propagate southeast today along a
weak baroclinic zone. This will result in a fairly narrow band of
shower activity along this same area. We utilized a blend of time
lagged RAP/HRRR as a guide for pops today. Will certainly need
some tweaks as we go through the day but they have been fairly
consistent with the overall development of this activity and match
up fairly well to the latest radar trends showing shower activity
from northwest ND into southern Saskatchewan. Thunderstorm
potential looks minimal but can not be completely ruled out this
afternoon in the south central. Also CAMS show some diurnally
driven isolated shower activity to the west of the main band of
showers this afternoon, thus we added a small area of slight
chance pops this afternoon in the far southwest and south central.

Ahead of this activity, there is a small area of southwest ND
(Hazen to Glen Ullin and Hettinger) that has fallen into the low
to mid 30s. Approaching clouds associated with the aforementioned
system will soon move into these areas so any impacts due to frost
are expected to be minimal. Most areas of the southwest and south
central remain in the upper 30s to mid 40s.

Tonight will likely be another cool night with surface high
pressure, light winds and clear skies over central ND at 12 UTC
Monday. Have lowered min temperatures tonight over a good portion
of central ND.

.LONG TERM...(Monday through Saturday)
Issued at 243 AM CDT Sun Jun 25 2017

Warm and humid with thunderstorm chances on Tuesday. Otherwise
seasonably cool through most of the long term period.

After a cool beginning on Monday we finally start to see a return
flow set up with warmer temperatures creeping into eastern Montana
by Monday afternoon. On Tuesday, a cold front will move into the
western Dakotas during the afternoon. Ahead of this we will see
warm temperatures and moisture return to the area with an
increasing southerly return flow. The thermal ridge pushes into
western ND Tuesday afternoon just ahead of the cold front. Not
quite sure why model and numerical guidance are not at least a
little warmer over western ND. GEFS plumes still indicate a mean
temperature in the low to mid 90s from Bismarck to Dickinson with
85h temps remaining around 25-27C. Have bumped up highs a little
over the southwest and south central closer to the GEFS mean
values. There is increasing mid and high level clouds that pushes
into the area mid to late afternoon, but until then we should see
good heating.

As for the thunderstorm potential, through 00Z we remain pretty
strongly capped. When the mid level trough pushes into the west
from 00Z-03Z Wednesday, the thunderstorm threat should increase as
the cap erodes. However, by then the wind profile begins to
become less favorable from west to east. It looks like a pretty
narrow window from around 00Z-03Z for possible severe storms,
with the potential diminishing thereafter. SPC Day 3 thunderstorm
outlook has a marginal risk of severe thunderstorms over the area,
which seems reasonable. If the upper trough were a little quicker
to move into the area, think the severe threat would be higher.
We`re still a couple of days away and will continue to monitor.

Beyond Tuesday, the upper low associated with this system begins
to drop south from Canada which keeps a chance of shower and
thunderstorms in the forecast through Friday, with another system
possible late in the weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1219 PM CDT Sun Jun 25 2017

For the 18Z TAFS, VFR conditions are expected. Scattered rain
showers associated with an upper level disturbance will exit the
region Sunday afternoon. High pressure will move over the region
tonight.

&&

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

$$

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