Area Forecast Discussion
Issued by NWS Bismarck, ND

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000
FXUS63 KBIS 171944
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
244 PM CDT Tue Oct 17 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 214 PM CDT Tue Oct 17 2017

Strong winds tonight into Wednesday and potential critical fire
weather conditions Wednesday afternoon highlight the short term
forecast.

A strong cold front will enter western North Dakota between 05-07
UTC tonight, and propagate east into central North Dakota by
early Wednesday morning. Strong west to northwest winds are
expected behind this front. The main challenge is how mixed the
post-frontal surface to 825 mb layer will become tonight. The RAP
iterations through the day and 12 UTC NAM soundings at Williston
late tonight suggest that a small inversion may remain in place,
while the 12 UTC GFS has consistently shown near adiabatic lapse
rates throughout the layer. The GFS has also been consistently
stronger with its wind field, and would even support a small
window for gusts in excess of 50kts across northwest and north
central North Dakota late tonight into early Wednesday morning.
For now given uncertainty in mixing tonight, issued a Wind
Advisory for northwest and north central North Dakota into the
Upper James River Valley through Wednesday afternoon. Gusts of
45-50 mph are forecast. A local upgrade to a High Wind Warning
will have to be monitored based on upstream observations if
adiabatic lapse rates can be established during the night behind
the front.

See the Fire Weather Discussion below for details regarding
potential critical fire weather conditions on Wednesday.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 214 PM CDT Tue Oct 17 2017

Above normal temperatures Thursday and Friday highlight the
extended forecast.

An upper level ridge is forecast to build across the Northern
Plains and Upper Midwest Thursday transitioning to southwest flow
aloft on Friday. This favors an anomalously warm airmass
characterized by 850 mb mean temperatures between their 90-99th
percentiles for the period as forecast by the 00 UTC NAEFS. High
temperatures of 70 to 80 are forecast each day, above the 12 UTC
guidance consensus. A windy Saturday is possible behind a cold
front, which will have to be monitored for possible critical fire
weather conditions as fuels dry this week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 214 PM CDT Tue Oct 17 2017

VFR conditions are forecast for the 18 UTC TAF cycle. Southwest
winds with gusts of 20-25 kts are forecast across western and
central North Dakota this afternoon. A strong cold front will
enter western North Dakota tonight, and move through central North
Dakota by early Wednesday morning. Strong northwest winds behind
the front with gusts of 35-45 kts are expected across northern
and much of central North Dakota, with slightly weaker winds
across the southwest. Low level wind shear is also possible across
much of western and central North Dakota tonight into Wednesday
morning.

&&

.FIRE WEATHER...
Issued at 214 PM CDT Tue Oct 17 2017

A Fire Weather Watch is in effect for northern and much of central
North Dakota Wednesday.

For northern and much of central North Dakota, strong west to
northwest winds are forecast on Wednesday behind a cold front.
Sustained winds around 30 mph with gusts to 45 mph are forecast.
Afternoon relative humidity will fall to near 20 percent. While
high temperatures will only be in the 50s, dry and windy
conditions may lead to critical fire weather conditions across
northern and much of central North Dakota. Across southwest North
Dakota, winds will be weaker on Wednesday, sustained around 20 mph
with gusts to 30 mph.

Warm conditions are forecast again on Thursday and Friday with
highs of 70 to 80. However, winds are not expected to be strong
either day. A windy Saturday is possible behind a cold front,
however, there is some uncertainty if relative humidity will
reach critical levels.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Wednesday afternoon through Wednesday
evening for NDZ001>005-009>013-021>023-025-035>037.

Wind Advisory from 4 AM to 7 PM CDT Wednesday for NDZ003>005-
011>013-023-025.

Wind Advisory from 2 AM to 4 PM CDT Wednesday for NDZ001-002-009-
010.

&&

$$

SHORT TERM...PA
LONG TERM...PA
AVIATION...PA
FIRE WEATHER...PA


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