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Area forecast discussion 
National Weather Service Bismarck ND
406 am CDT sun Jul 31 2016

Short term...(today and Monday night)
issued at 337 am CDT sun Jul 31 2016

Forecast highlights in the short term period will be chances for
thunderstorms through the period along with much warmer
temperatures. Severe storms will be possible this afternoon and
night, and again Monday afternoon and evening.

Currently, an upper level low was over British Columbia/Alberta. An
upper level shortwave impulse ahead of the western Canadian low was
moving east across Montana/Wyoming. A weak upper level impulse was
over the eastern Dakotas and moving east into Minnesota. A
southerly low level jet was well established over the Western
Plains. An area of thunderstorms that developed over central Montana
moved east into western ND early this morning, but decreased in
intensity. Meanwhile isolated thunderstorms developed over Kidder
County. This appears to be in the vicinity of an h850 speed Max of
around 35 knots. The latest iterations of the hrrr model did develop
storms between Bismarck and Jamestown, and also develops isolated
storms over the eastern third of ND early this morning. Have added
mention of slight chance of thunderstorms there early this morning.
Another question is the current convection over western ND that had
weakened. The hrrr indicates this holding together and moving east
into central ND and remaining in tact until around 10-11 am CDT.
Other short term models do not favor this, but this convection may
persist due to the lift associated with the low level jet. Mixed
layer cape is also fairly strong at around 1000 j/kg. For now
the short term consensus models do not depict this and will keep the
decreasing chances of precip in the west this morning. Confidence
low, and will continue to monitor for needed updates.

Today and tonight, the western Canadian closed upper low
continues to develop and move east to the Saskatchewan/Manitoba
border by daybreak Monday morning. A surface trough ahead of the
system was currently over sask/Mt/WY and is forecast to move into
western ND by around noon. The low level jet remains well
established ahead of the surface trough, and upper level energy
impulses along and ahead of the trough will move east across the
state. Surface dewpoints in the lower 60s this morning should
increase to the upper 60s/lower 70s ahead of the surface trough.
High temperatures should be in the mid/upper 80s, with mid 90s
along and west of the surface trough - where the mid-level thermal
ridge sets up. Most unstable cape values of around 500-1000 j/kg
this morning will increase to 5000+ j/kg this afternoon, combined
with 0-6km bulk shear values of 40-50 knots. Storm Prediction
Center has elevated our risk of severe storms from "marginal" to
"slight" chance for today/tonight. Will mention "possibly severe"
wording for this afternoon and tonight. Best chances of
thunderstorms will be the initiation this afternoon in the west in
the vicinity of the surface trough. Better chances expand into
central ND this evening.

On Monday, the Canadian low continues moving east, reaching Manitoba
Monday night. The northern portion of the surface trough continues
moving eastward slowly...setting up over Manitoba. The southern
portion however lags farther west with a southern surface low
developing over western South Dakota. This sets up the trough over ND in a
northeast-southwest fashion from northeastern ND to south central ND
Monday morning, finally moving east of the state by Monday night.
Strong to severe storms will also be possible Monday along and east
of this surface trough, where higher dewpoints continue to pool
ahead of the trough. Cape and shear values remain high along and
east of the trough. Chances of thunderstorms will remain over
central and southwestern ND daytime Monday, with lingering chances
in the James Valley Monday evening.

Long term...(tuesday through saturday)
issued at 337 am CDT sun Jul 31 2016

Two features will impact the extended period and both are closed
h500 lows. The first, by Tuesday, will be exiting the region by way
of Ontario leaving a shortwave ridge between it and the next h500
low over the Pacific northwest. This ridge should suppress
convection on Tuesday as both GFS/European model (ecmwf) have minimal cape so will
leave the pops out.

However, by Tuesday night the upstream shortwave will approach and
bring better chances for thunderstorms again across west and central
North Dakota with better shear and cape returning. Favorable
conditions for thunderstorms will extend into Wednesday night.
Thursday and Friday do not have enough confidence to add pops as the
upper flow becomes oriented northwesterly as the wavelength between
the two upper lows shortens and they merge over Hudson Bay leaving a
broad northwest flow across the northern plains. This time of the
year northwest flow often remains somewhat active but will
not mention any precip until Saturday night.

Warmest days of the week will be Tuesday and Wednesday with highs in
the upper 80s and lower 90s. The far southwest which has been
relatively dry of late will see minimum relative humidity near 20
percent. Will keep an eye in winds during this period for any fire
weather concerns that pop up.


Aviation...(for the 06z tafs through 06z Sunday night)
issued at 337 am CDT sun Jul 31 2016

Low pressure with an associated cold front in central Montana is
forecast to move east today. The front will be the focus for
thunderstorms late Sunday afternoon and evening.

Thunderstorms are the main aviation hazard today. Early morning
thunderstorms in central North Dakota will active through sunrise.
Then expected to generally diminish with time. A more significant
line of thunderstorms will form along the cold front Sunday
afternoon. Kmot-kbis will see the best chance 00-06z. VFR
conditions expected outside of thunderstorms.


Bis watches/warnings/advisories...


Short term...jv
long term...warm air advection
aviation...warm air advection

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