Area Forecast Discussion
Issued by NWS Grand Forks, ND

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204
FXUS63 KFGF 151808
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
108 PM CDT Tue Aug 15 2017

.UPDATE...
Issued at 108 PM CDT Tue Aug 15 2017

Band of isolated sprinkles/light rain entering a drier airmass as
it approaches the valley. The stronger forcing and more widespread
showers now (100pm) across central North Dakota will affect
northeast North Dakota and the northern Red River Valley later
this afternoon into the evening hours. For the remainder of the
overnight into Wednesday, a couple more upper waves should eject
into the region, with each subsequent wave affecting areas a bit
further south than the previous wave. Heavy rain no longer
considered a threat, and most areas will remain under an inch
rainfall thorugh Wednesday. Updated PoPs/Wx/QPF for this latest
thinking and tried to time higher PoP chances through Wednesday.

&&

.SHORT TERM...(Today and tonight)
Issued at 332 AM CDT Tue Aug 15 2017

The main forecast challenge is the next pcpn event, which is
mainly contained within this time range. Models had been showing
the potential for another round of 1 to 2 inches of rain across
the southern half of the FA. Latest runs have been pushing the
heavier rainfall south of the FA now, more so from southeast SD
into southern and eastern MN. Still could see amounts around an
inch or so, mainly south of a line from Valley City to Bemidji.
After coordinating with adjacent offices and WPC, reduced the
overall rainfall amounts to match this further south solution and
dropped the marginal risk for excessive rainfall from our FA. The
overall lack of much instability in our FA will limit the overall
thunder chances, and without organized thunderstorms there is
generally a reduced heavy rain threat. So will be putting out our
various products with this message. There is not a threat of
severe weather and the reduced expected rainfall should not cause
any issues for the area. The event also looks to occur over a
shorter time range than the models were showing yesterday too. So
looking at mainly a tonight event for the steadier rainfall
amounts, then more so in MN by Wed.

Other than the rainfall, there is also some morning fog. At this
point, it is not dense, but will have to monitor. The fog so far
has been over the eastern and southwest FA. High clouds spreading
in from the west may limit the fog from being as extensive as
yesterday morning. These clouds will continue to spread into the
FA today, with pcpn chances slowly spreading from west to east.
Think through most of the day, this rain will stay west of the Red
River.

.LONG TERM...(Wednesday through Monday)
Issued at 332 AM CDT Tue Aug 15 2017

Some of the above mentioned rain will linger into Wed and Wed
night, but mainly over the MN portion of the FA. This will hold
down high temps on Wed, while clouds decrease from west to east
Wed night. With light winds again, there may be some fog around
again Wed night, however will hold off on mentioning it at this
point. Thu looks like a pretty nice day, with mild highs and
continued low wind speeds. Next chance of pcpn will spread into
the FA Thu night.

For Friday through Monday...High pressure moving toward eastern
Minnesota Thu night will be replaced by advancing sfc
boundary/digging short wave early Fri. Severe potential may be
minimal, with weak shear coupled with moderate instability at
best, during Fri morning.

The weekend looks warmer and dry, owing to building high pressure
both at the surface and aloft. The next threat for convection would
most likely arrive with the approach of a short wave on Mon. The GFS
and ECMWF closely agree on the timing of these features.

Temps will be near seasonal Fri, rising to the low and mid 80s for
the weekend and beyond.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 108 PM CDT Tue Aug 15 2017

Cigs will be trending lower through the period, eventually into
the MVFR (potentially IFR) category. On and off again rain
chances, and tried to time the best chances for each site.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&

$$

UPDATE...TG
SHORT TERM...Godon
LONG TERM...WJB/Godon
AVIATION...TG



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