Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 192350
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
650 PM CDT Fri May 19 2017

.UPDATE...
Issued at 639 PM CDT Fri May 19 2017

Going forecast remains in good shape. Only changes were to blend
in current conditions.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 246 PM CDT Fri May 19 2017

Main highlight is a freeze warning portions of southwest ND,
including Adams/Hettinger/Grant Counties. A frost advisory
surrounds the rest of western ND and central ND, with the
exception of the James River Valley, where clouds should inhibit
temperatures from falling into frost advisory conditions. Both
the freeze warning and frost advisory will be valid from 06z/1am
CDT Saturday through 14z/9am CDT Saturday.

Mainly sct/bkn high clouds continue per latest visible satellite
imagery this afternoon. Expectations of lowering and thickening
of clouds across the James River Valley late tonight as the upper
low moves into South Dakota, with increasing chances for showers
during the day Saturday. That will leave the west and portions of
central ND with thinner clouds overnight, allowing a better
opportunity for radiational cooling.

The latest water vapor imagery loop shows an upper low over
central Colorado which is forecast to move northeast through the
short term period. This places the low into southeast South Dakota
Saturday afternoon, then across Minnesota into western Great
Lakes Sunday evening.

For Saturday, partly cloudy/warmer west with more clouds/cooler
south central. Scattered/numerous rain showers James River Valley
which will be closest to the upper low. Highs in the low to mid
60s west and north Saturday, with 50s elsewhere.

.LONG TERM...(Saturday night through Friday)
Issued at 246 PM CDT Fri May 19 2017

Cyclonic flow fairly pronounced across western/central ND
Saturday night through Monday night with the upper level low from
the short term period shifting into the western Great Lakes.
Patchy frost is forecast Saturday night across southwest and south
central ND. Future shifts can assess this. A shortwave trough and
associated surface cold front over central Saskatchewan Sunday
will move southeast through Monday. A weak surface trough ahead of
the main cold front will be in place across the west and central
Sunday afternoon. SPC has western ND in a General Thunderstorm
Outlook area, and the latest SREF populates/conveys this threat in
the gridded forecast. Between the NAM/GFS, Most Unstable Cape
250-400 J/Kg, 0-6km Bulk Shear 20kt-25kt, and mid level lapse
rates 7C to 7.5C/km Sunday afternoon and evening. The shortwave
trough and surface cold front shift south Sunday night through
Monday morning with a chance of showers across western and most of
central ND, along with thunderstorm chances continuing Monday in
southwest ND. Northerly flow takes control Monday for a cooler
day, with highs in the lower 60s. Another shortwave is forecast
within the cyclonic flow Monday evening for a chance of showers
continuing, before dwindling and ending after 06z Tuesday.

Upper ridge in the northern Rockies will nudge closer to western
and central ND Tuesday and Wednesday, with the GFS and ECMWF out
of phase thereafter. The ECMWF is quicker pushing the ridge east,
allowing another shortwave trough across western/central ND
Wednesday night/Thursday. The Operational GFS/GFS Ensembles hold
onto the northern Rockies ridge into Thursday while keeping the
shortwave trough farther west until Friday. The model blend keeps
a dry forecast Tuesday through Thursday, then brings in a chance
of showers Thursday night and Friday. This seems reasonable given
the uncertainty this far out. After highs in the 60s Tuesday,
temperatures are forecast to rise into the low/mid 70s Wednesday
through Friday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 639 PM CDT Fri May 19 2017

MVFR cigs may develop late Saturday afternoon over the James River
Valley. Otherwise, VFR conditions will prevail.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 1 AM CDT /midnight MDT/ to 9 AM CDT /8 AM
MDT/ Saturday for NDZ001>005-009>013-017>023-031>036-040-043-
045>047-050.

Freeze Warning from midnight tonight to 8 AM MDT Saturday for
NDZ041-042-044.

&&

$$

UPDATE...JJS
SHORT TERM...KS
LONG TERM...KS
AVIATION...JJS



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