Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 270703
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
203 AM CDT Thu Jul 27 2017

.UPDATE...
Issued at 203 AM CDT Thu Jul 27 2017

Latest satellite and radar imagery shows mid level cloud tops
cooling and subsequently higher reflectivities with multiple
lightning strikes in northwest ND. With MU Cape around 500 J/Kg
and Effective Shear of 50kt along with decent mid level lapse
rates of 7C/Km, expecting coverage to expand over the north
central, and possibly reach into portions of south central before
sunrise per latest CAM`s. Updates to text products forthcoming.

UPDATE Issued at 1150 PM CDT Wed Jul 26 2017

Latest regional radar showing weak returns in northeast Montana
with an increase in mid level clouds across most of western ND.
RAP soundings from Williston to Dickinson, and Bowman indicate
increasing vertical motion overnight with the previous mentioned
low level jet taking control for the next few hours. The
HRRR/RAP13 and NBM have similar forecast trends with the pops
favoring the northwest overnight. Have kept the southwest with
slight chance, but have increased pops farther north based on
radar and the latest high resolution model trends.

UPDATE Issued at 939 PM CDT Wed Jul 26 2017

A few clouds linger over southwest North Dakota where low level
jet is expected to intensify later this evening. Still not
confident anything will develop, but the potential is there for
some convection so will keep low precipitation chances in for late
tonight.

UPDATE Issued at 639 PM CDT Wed Jul 26 2017

Quiet weather continues early this evening with no changes needed
to current forecast.

&&

.SHORT TERM...(This evening through Thursday)
Issued at 230 PM CDT Wed Jul 26 2017

Surface analysis shows high pressure centered over the southern
Saskatchewan/Manitoba border, bringing sunshine with a few fair
weather cumulus clouds and calm winds to the state. Further
upstream several upper level impulses depicted on water vapor
imagery over Idaho and Nevada were causing surface pressure to
fall over central Montana. A corridor of meager high based
instability was present in southeastern Montana, possibly into far
southwestern North Dakota, aided by dew points that managed to
reach into the low 50s. With the majority of the dynamic forcing
still upstream and the weak instability profiles, several
convection-allowing model runs have still managed to squeeze out a
few signs of thunderstorm activity in our far southwest. Given
the wide low level dew point depressions and lack of a steep lapse
rate overlay, thunderstorm threats will mainly stick to gusty
winds. Into the overnight hours a secondary chance of elevated
convection is possible on a strengthening low level jet over the
western half of the state, though not expecting many strong
storms with this activity.

On Thursday a brief period of southerly return flow through the
west will allow for at least somewhat of a CAPE/shear profile
possible for convective activity ahead of mid-level shortwave.
While model consensus shows that CAPE values will struggle to
reach 1000 J/kg, deep layer shear values up to 30-40 kts in the
southwest will bring a marginal chance of severe weather.

.LONG TERM...(Thursday night through Wednesday)
Issued at 230 PM CDT Wed Jul 26 2017

Early Friday the second 700mb wave arrives from the west bringing
another chance of showers and thunderstorms for the far west,
especially on the nose of an early morning 850mb low level jet.
Chances for convection will continue into the Friday evening hours
as the surface trough axis shifts from west to east, however
likelihood of severe weather will depend on atmospheric recovery
behind the earlier convective activity.

Going into this weekend the upper level ridge builds once again
keeping the area dry with highs into the 80s and a few spots in
the low 90s. GFS/ECMWF agreement indicates the upper level ridge
shifting off to the east by the beginning of next week, marking
the next chance for precipitation.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1150 PM CDT Wed Jul 26 2017

For this Taf period, a vcts was mentioned at KISN/KMOT/KDIK at
various times. It appears that any precipitation would be isolated
through 18z Thursday, then perhaps increasing in coverage across
western ND Thursday afternoon through the evening. No mention of
precipitation at KBIS or KJMS.


&&

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

$$

UPDATE...KS
SHORT TERM...AE
LONG TERM...AE
AVIATION...KS


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