Area Forecast Discussion
Issued by NWS Bismarck, ND

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590
FXUS63 KBIS 281729
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1229 PM CDT Wed Jun 28 2017

.UPDATE...
Issued at 1222 PM CDT Wed Jun 28 2017

Clouds are more persistent across the James River Valley so
adjusted back to cloudy most of the afternoon. Matched up with
the western offices and added a slight chance of showers for the
southwest this afternoon where weak showers continue to move east
through Montana.

UPDATE Issued at 950 AM CDT Wed Jun 28 2017

Updated cloud cover as satellite loops shows more extensive clouds
through the James River Valley. Otherwise current forecast looks
good.

UPDATE Issued at 550 AM CDT Wed Jun 28 2017

A narrow line of showers and isolated thunderstorms have
re-developed from southeast Rolette County to southern Pierce and
into Sheridan county. Also, a few weak cells were moving into
northern Burleigh county from Sheridan county. It appears they
are developing along a final shortwave/vort lobe per 06z GFS,
which shifts into the northern James River Valley by 15z. Thus
will extend the mention of precipitation along this line and areas
east until 10Am CDT.

&&

.SHORT TERM...(Today and tonight)
Issued at 245 AM CDT Wed Jun 28 2017

For the near term, now through sunrise, the latest water vapor
imagery shows a departing shortwave trough, which produced the
showers/thunderstorms yesterday evening, is now into exiting the
James River Valley. Radar loop shows a mid level circulation over
Wells County with showers continuing to shrivel and shift east.

A brief mid/upper level transitory ridge progresses through western
and central ND this afternoon. However, a subtle shortwave in
southwestern Montana early this morning slides east today,
increasing vertical motion in eastern Montana/southwestern ND this
afternoon. Global models show some precipitation approaching the
western border by 00z Thursday, while the higher resolution models
produce some showers this afternoon in the west. The gridded
forecast portrays this signature to an extent, and will leave it
in there for now and let the dayshift evaluate/monitor. Elsewhere,
dry and not as warm today, but still pleasant. Expect northerly
winds between 10 and 20 mph, with afternoon highs reaching the
upper 70s to lower 80s.

Looking farther upstream, a mid/upper level closed low was seen
circulating over central Alberta. This upper low is forecast to
slide into southeast ALberta this evening, then into southwest
Saskatchewan by 12z Thursday. In doing so, surface low pressure
develops with an attending cold front, stretching from Swift
Current, Saskatchewan back across northern Montana this evening.
This surface low and cold front will edge slowly east tonight,
just nosing into northwest ND by sunrise Thursday. Isolated to
scattered showers will develop across the west overnight tonight.

The NAM/GFS indicate a few hundred joules of CAPE developing in
the far northwest after midnight, and with the proximity of the
surface low, cold frontal position, and sufficient mid level
lapse rates, a thunderstorm or two is not out of the realm of
possibilities. Thus will trend the forecast to mention thunder in
the northwest late tonight, with showers mentioned elsewhere in
the west.

.LONG TERM...(Thursday through Tuesday)
Issued at 245 AM CDT Wed Jun 28 2017

A temperature swing occurs again, with a downward trend through
Friday (highs in the 60s Friday); followed by a warming trend with
highs in upper 80s to lower 90s Monday through Wednesday.

The abnormally cooler air is a result of a surface cold front
slated to slowly move across western and central ND Thursday into
Thursday night. This will be followed up by the closed mid/upper
low mentioned in the short term period, sliding through during the
day Friday. Scattered showers and thunderstorms expected Thursday
and Friday. Looking at the Cape/Shear values on both the NAM/GFS,
would not expect severe weather as values are weak/low. High
temperatures Thursday in the 70s, then 60s Friday as mentioned
above.

For the weekend, partly to mostly sunny and dry with a moderating
trend as northwest flow transitions to broad ridging. Highs in
the 70s Saturday, then 70s to lower 80s Sunday.

Warmer Monday through Tuesday. The GFS is more active than the
ECMWF. The GFS produces showers/thunderstorms Sunday night, while
the ECMWF keeps it dry. The gridded forecast has a slight chance
of showers/thunderstorms Sunday night, and probably is a good
compromise given the uncertainty. Tuesday is also dry in the
ECMWF, with the GFS pushing a quick surface low and frontal system
across the northwest and north central along with some
precipitation. The gridded forecast again looks like a compromise
between the two models. The main message is warm both days, with a
much greater dry time verses any wet periods.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1222 PM CDT Wed Jun 28 2017

Low pressure over eastern North Dakota will maintain MVFR
conditions at KJMS for a few hours this afternoon before becoming
VFR. Otherwise all TAF sites VFR.


&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...WAA
SHORT TERM...KS
LONG TERM...KS
AVIATION...WAA



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