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Area forecast discussion 
National Weather Service Bismarck ND
630 PM CDT Tuesday Jul 7 2015

issued at 613 PM CDT Tuesday Jul 7 2015

Two areas of thunderstorms continue to move through the
region...with the first one moving from northwest into north
central North Dakota and the second moving through southwest North
Dakota. Right now storms are in the axis of greatest instability
(~ 1 kj/kg) but will move to the east of this over the next few
hours. Therefore...expect the limited severe threat to be on the
decrease as the evening moves on.


Short term...(this evening through wednesday)
issued at 234 PM CDT Tuesday Jul 7 2015

The main forecast issue for the short term period will be
thunderstorm chances this afternoon/evening across the west and in
the central Wednesday.

Currently...scattered thunderstorms have developed over far
northeast and southeast Montana...poised to move into western
North Dakota. Slightly unstable airmass exists over western North
Dakota with sb convective available potential energy around 1000-1500 j/kg...with steepening low
level lapse rates and increasing bulk shear. Middle level lapse rates
are lagging across the west with best shear remaining over the
southwest. Will continue a mention of thunderstorms west this
evening. Could still be a few strong to potentially severe
storms...most likely over the southwest. But enough limiting factors
to leave out a mention of severe.

Tonight...convection is expected to move into central North Dakota
tonight. Latest iterations of the rap/hrrr continue to indicate
the showers outpacing the instability. Thus the potential for
thunder after late this evening and after midnight will
diminish...but did keep a mention of isolated thunder across the
central tonight. Could be some patchy fog on the back side of the
showers that move through. Also...will keep a mention of smoke
through tonight.

Wednesday...frontal boundary lingers over eastern portions of
central North Dakota Wednesday with morning showers and afternoon
thunder. At this time it looks like the best instability and
forcing will be east of the forecast area...limiting the potential

Long term...(wednesday night through tuesday)
issued at 234 PM CDT Tuesday Jul 7 2015

A departing surface cold front/upper shortwave/jet streak in the
James River Valley will result in diminishing chances for
showers/thunderstorms early Wednesday night. Dry weather follows the
rest of Wednesday night through Friday morning as 700mb-500mb
ridging develops. This ridging is out ahead of a southwest upper
flow induced by a closed upper low/upper trough working onshore from
California...which is forecast to eject northeast with time. As
mentioned this will keep warm/dry weather over western and central
North Dakota Thursday into Friday. A lead midlevel shortwave trough
ejecting across Wyoming/Montana will induce a surface low pressure
in southeast Montana Friday evening. A slight chance of
showers/thunderstorms in the far west Friday afternoon in the
vicinity of the surface low and approach of the shortwave. The
shortwave and surface feature is forecast to shift into northeast
Montana and northern North Dakota Saturday...then drop southeast
into the James River Valley Sunday. A chance for showers and
thunderstorms will accompany this pattern...however the highest
chances will remain in the north near the vicinity of the upper low
and surface low. For Monday and Tuesday...shortwaves continue to
migrate over broad ridging in place. The European model (ecmwf) is more aggressive
than the GFS in generating precipitation. The portrays a slight
chance for showers/thunderstorms and concur at this time.


Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 613 PM CDT Tuesday Jul 7 2015

Isolated/scattered thunderstorms and rain will decrease in coverage this evening with mainly
lingering -shra overnight. Patchy fog possible late tonight in the
wake of the storms/showers reducing visibilities. Patchy smoke
from wildfires will also continue. Otherwise...VFR conditions


Bis watches/warnings/advisories...


short term...twh
long term...twh

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