Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 210234
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
934 PM CDT FRI MAY 20 2016

.UPDATE...
Issued at 929 PM CDT Fri May 20 2016

Quick update to blend to observed trends through 02 UTC. Overall,
the window for an isolated thunderstorm across far southwest
North Dakota this evening is quickly closing and scaled back PoPs
into tonight.

UPDATE Issued at 634 PM CDT Fri May 20 2016

Other than to blend to observed trends through 23 UTC, forecast
expectations remain unchanged for the remainder of the evening and
overnight. The 18-22 UTC high resolution suites are in agreement
on convection remaining in Montana in the vicinity of the surface
trough through the night.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 247 PM CDT Fri May 20 2016

Latest water vapor imagery details a shortwave trough sliding south
into the James River Valley this afternoon. Meanwhile a closed low
and deep upper trough in the west is forecast to lift north and then
move east through the short and into the long term period. Visible
imagery shows some vertical motion to these clouds and Bowman
radar trend shows some enhancement to the reflectivitys. Thus will
mention a slight chc of a shower or thundershower this afternoon
far southwest.

As the upper low lifts north, a mid to upper level ridge will
amplify across central and eastern North Dakota tonight through
Saturday. A decent mid level cap develops and remains in tact
across western North Dakota through 00z Sunday. The net result
will be dry and warmer central Saturday with convection being
suppressed until Saturday evening. Increasing southeast flow in
southwest North Dakota ahead of an approaching cold front has lead
to the issuance of a wind advisory Saturday mid morning through
early Saturday evening. Expect sustained winds to 35 mph and gusts
to 50 mph in southwest ND Saturday. It will be breezy elsewhere. Highs
Saturday will be in the 80s across western and central ND.

.LONG TERM...(Saturday night through Friday)
Issued at 247 PM CDT Fri May 20 2016

Main weather highlight will be severe thunderstorm expectations west
Saturday night and into Sunday morning, then shifting into south
central ND Sunday afternoon and evening.

Severe thunderstorms in Montana will impinge into our western
counties late Saturday evening through Saturday night. Despite some
likelihood of the cap eroding across the west, soundings still
support enough of a cap to inhibit any large area of severe weather
at this time. The better threat for severe weather comes mid to late
afternoon Sunday and into Sunday evening for south central ND.

Interesting to note though that with a deep and unidirectional
southerly flow Saturday night into Sunday afternoon across central
ND, the MET/MAV and consequently their soundings show a decent layer
of stratus developing in central ND Saturday night through mid
Sunday afternoon. As the cold front approaches Sunday afternoon, mid
level winds turn southwest which is expected to produce drying and
erode the stratus layer. This introduces complexity in the
forecast as the timing of stratus erosion, and axis of most
unstable cape and shear may or may not become disjointed, causing
a narrower window of severe weather than what may be anticipated.
Much uncertainty on the coverage of severe weather at this time
due to the above. Will need to watch this closely for any changes
in clearing and destabilization. Thunderstorms are forecast to
shift into the James River Valley Sunday night.

A break Monday morning, however southwest flow aloft will keep
the threat of daily showers and thunderstorms going Monday
afternoon through Friday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 929 PM CDT Fri May 20 2016

Strong southeast winds are expected once again on Saturday with
gusts of 25-35 kts. Thunderstorms are possible across western
North Dakota after 00 UTC Sunday. VFR conditions are forecast for
the 00 UTC TAF cycle.

&&

.BIS Watches/Warnings/Advisories...
Wind Advisory from 9 AM to 9 PM MDT Saturday for NDZ031>033-040-
041-043-044.

&&

$$

UPDATE...AYD
SHORT TERM...KS
LONG TERM...KS
AVIATION...AYD



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