Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 241750

Area Forecast Discussion
National Weather Service Bismarck ND
1250 PM CDT FRI JUN 24 2016

Issued at 1250 PM CDT Fri Jun 24 2016

Surface low center was near Bowman/Hettinger/Bison SD at noon cdt.
Southeasterly winds ahead of the low continued to advect low level
moisture into our region...with surface dewpoints well into the 60s
across central and even into northwestern North Dakota. Low level
instability was increasing with surface based CAPE values of 1000-
1500 J/Kg...but CIN values of 150-400 J/Kg reflect the strong
thermal cap already established. Latest meso analysis suggests H700
temperatures of +14C in southwestern North Dakota and +10 from the
Divide County area to the Turtle Mountains. This cap should continue
to build through the day, which should inhibit convection. Some
models suggest no convection this afternoon in North Dakota...while
a couple models suggest some convection at the boundary between the
western edge of the low level jet, the surface dewpoint boundary
between lower 60s southwest and upper 60s/70 to the east. The area
in question would be mainly east of Bismarck to the James Valley and
northward towards the Turtle Mountains and Devils Lake basin. Thus
will keep the slight chance mention of afternoon thunderstorms in
the Turtle Mountains area but also bring the slight mention farther
south into the Stutsman/Logan/LaMoure area for late afternoon.

UPDATE Issued at 1023 AM CDT Fri Jun 24 2016

Convection has generally moved east into eastern North Dakota. At
this time we are not expecting much in the way of late morning
convection. The next upper level impulse enters southwestern North
Dakota this afternoon...but strong capping already underway this
morning should inhibit early afternoon storms in the western half
of the state. Latest high res models show a hint of some
convection possible in the Turtle Mountain/Devils Lake area this
afternoon, but some show nothing - may be related to the strength
of the cap farther east.

Otherwise the main change this update was to increase southerly
winds over eastern portions of central North Dakota today to 15 to
20 mph. We may have to revisit this as we see how high up the
surface winds can tap into higher winds aloft.

UPDATE Issued at 650 AM CDT Fri Jun 24 2016

Main change with update was slight adjustments to pops to account
for convection that flared up just west of Jamestown. Per SPC meso
page, continue to see around 1000 J/KG of elevated CAPE and 40
knots of 0-6 km shear, combined with low level jet helping to
support isolated storms in this area.


.SHORT TERM...(Today and tonight)
Issued at 448 AM CDT Fri Jun 24 2016

The main concerns for the forecast are severe storm potential
today and tonight as strong upper low pressure system approaches,
followed by strong winds on Saturday behind the storm. On the
synoptic scale, water vapor imagery shows deep upper low pushing
inland over the Pacific Northwest with upper level ridge axis
centered over the Dakotas, progressing eastward. Weak surface low
was analyzed over southeast Montana with warm front trailing
southeast from the low. SPC mesoanalysis showed axis of around 1000
J/KG of MUCAPE across southwest ND coincident with 50 knots of
effective shear, supporting a few strong thunderstorms across our
south, also supported by low level jet.

For today, models (both global and CAM solutions) support
increasing low level instability especially across the east as low
level southerly flow continues to advect surface dew points well
into the 60s into the state. Late afternoon CAPE gets as high as
4000-5000 J/KG over the eastern half of the state, with strong
directional and speed shear. However, the limiting factor is
significant capping with CIN values per GFS/NAM over 400 J/KG
through 18z decreasing to less than 100 J/KG after 21Z. Most CAM
solutions greatly limit convection through the period either
showing no convection or weak convection over ND with stronger
cells developing north of the border in Canada. Needless to say,
will need to monitor closely, in case capping turns out to be
weaker than expected, any storms that develop could easily be
severe with a tornadic threat as well.

Higher confidence in storm activity as main surface low and upper
level forcing move into the state this evening. Some differences
exist in timing with CAM solutions, but appears to be around 03Z
when widespread convection increases across the west as low
pressure system and associated cold front move into the state. 00Z
NSSL-WRF also indicates potential supercells moving into southwest
part of the state by 03Z. SPC has continued slight risk of severe
thunderstorms for the northern half of the state, mainly north of
I-94, with the marginal area for points south.

.LONG TERM...(Saturday through Thursday)
Issued at 448 AM CDT Fri Jun 24 2016

Main upper level low will be centered just north of the state at
00Z Sunday and continues to lift to the northeast. Lingering
showers and thunderstorms are expected across the north but the
bigger impacts are expected from wind behind the system. Models
continue to indicate strongest winds over the southwest with
forecast soundings mixing to 700 mb with 40 to 50 knots of wind
near the top of boundary layer. Continues to look like at least
wind advisory criteria will be met over much of the southwest into
possibly central ND on Saturday. Breezy conditions expected again
on Sunday with a continued chance of showers and thunderstorms
over northeast areas. High temps from Saturday through Tuesday
will be in the 70s, with a gradual warm up by mid-week to the 80s.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1250 PM CDT Fri Jun 24 2016

VFR conditions will generally prevail through Saturday. However,
there is a chance of thunderstorms with local MVFR/IFR conditions
late this afternoon through tonight. We carried a VCTS at KISN,
KDIK, and KMOT tonight where the chance of storms is highest in
advance of a cold front. Winds will shift westerly with gusts of
30 to 40 kt behind the front, beginning late tonight southwest
and spreading over all of the west and central Saturday. There is
also a low chance of MVFR or IFR ceilings just behind the front.


.BIS Watches/Warnings/Advisories...


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