Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 190628
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
128 AM CDT Wed Apr 19 2017

.UPDATE...

Issued at 128 AM CDT Wed Apr 19 2017

Temperatures dropping where the sky remains clear so hourly trends
were adjusted a bit. Clouds increasing from southwest to northeast
so would expect some of these observation points to rebound/warm
over the next few hours. Thus overall overnight lows were only
tweaked slightly.

I delayed the onset of POPs over southwestern ND a few hours, but
then increased to likely/categorical as precipitation develops
into our area. Wed/Wed night grids were also adjusted to increase
the coverage of showers and increase the percentage. Also
reintroduced thunder back into the west central/northwest for Wed
aft/eve as SREF t-storm probs consistently indicate some
potential.


UPDATE Issued at 936 PM CDT Tue Apr 18 2017

Main change for this update was to delay the onset of
rain chances across southwest ND by a couple hours. The 19.00z NAM
holds off the rain chances until near 19.12z, which is close to
the HRRR timing.

UPDATE Issued at 636 PM CDT Tue Apr 18 2017

Only made small changes to the going forecast to blend in current
conditions. The fog forecast remains a challenge, though the HRRR
and SREF both suggest at least some restriction in visibility
will occur late tonight into early Wednesday morning. The rain
chances for late tonight into Wednesday still look reasonable,
though we may be bringing the chances in a little too quick. Will
take another look, and consider slowing the timing in the next
update.

&&

.SHORT TERM...(This evening through Wednesday)
Issued at 249 PM CDT Tue Apr 18 2017

Weather features as of Tuesday afternoon include a cold frontal
boundary extending from low pressure across Minnesota through
South Dakota. The frontal boundary/baroclinic zone then extends
into Montana in what will remain a quasi-stationary frontal zone.
This will be the focus for increasing chances of rain across the
west and south late tonight and Wednesday.

There is some uncertainty on the potential for fog tonight. On one
hand the cool boundary layer and area of stratus across much of
central North Dakota will be favorable for fog formation as the
stratus erodes this afternoon and evening. This combined with the
abundant low level moisture from the rainfall last night would
increase the likelihood for fog. On the other hand increasing mid
level clouds may tend to inhibit fog. Will favor the fog argument
initially then diminish it late tonight as the clouds increase.

On Wednesday the best chances of rain will be south and west with
the influence of surface high pressure across the northeast
holding off precip chances there.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 249 PM CDT Tue Apr 18 2017

The extended period will be at first mainly dry as h500 fractured
flow/rex blocking across the north central CONUS Thursday and
Friday breaks down to a broad flat ridge by the weekend. This will
support at least near normal to above normal temperatures with
low or no pops until Monday and Tuesday when progressive short
wave energy brings the next chance for rain. Highs will be in the
mid 50s and 60s through the weekend then cooling to the 40s/50s
Monday and Tuesday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)

Issued at 128 AM CDT Wed Apr 19 2017

Observations across western and central ND early this morning
show a few spots reporting variable visibilities in fog. Short
term models suggest the best chances for fog at terminals will be
KDIK, KISN and KMOT. Will not go too low with visibilities at
those locations for now, but could see rapid fluctuations in
visibilities if fog does reach those spots. The next concern will
be rain chances as a storm system moves across the region on
Wednesday. The best rain chances will be across the southern and
western part of the state, and have added light rain with
unrestricted visibility but lower ceilings.


&&

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

&&

$$

UPDATE...NH
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...CK



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