Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 121821
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
121 PM CDT Sat Aug 12 2017

.UPDATE...
Issued at 945 AM CDT Sat Aug 12 2017

Light rain approaching JMS now however north of Carrington-Harvey
area looks more like virga/clouds on latest radar trends. Have
adjusted POPs with latest CAM guidance which slows arrival into
Valley City down an hour and slightly lowers POPs further north
through 00Z. No changes to temps at this time.

UPDATE Issued at 706 AM CDT Sat Aug 12 2017

The echoes on radar have pushed east of a Minot to Bismarck line,
and could approach western Benson or western Eddy counties in
another hour or two. High resolution model guidance keeps some low
chances for pcpn from western Benson county down through Barnes
county from mid to late morning. This is a little faster than
expected, so updated the forecast with this timing in mind. Still
think that with heating this morning, additional afternoon pcpn
development is possible from Devils Lake down through the Wahpeton
and Breckenridge area. Some of the high resolution models show
development even further east, but will keep that area dry for
now, and later shifts can monitor that possibility. The thicker
cloud cover has also crept into the Devils Lake to Jamestown
corridor, so updated the cloud forecast to account for that too.

&&

.SHORT TERM...(Today and tonight)
Issued at 320 AM CDT Sat Aug 12 2017

Main forecast challenge will be pcpn chances and rainfall amounts
mainly across the southern half of the FA today through Sunday
night. Currently there is an area of showers and thunderstorms
just west of a Bismarck to Minot line. There are also some
showers over central SD. This activity should stay west and south
of the FA through 12Z. However, some of the pcpn may start to move
into the southwest FA by late morning and continue over the
southern FA through the afternoon. Cloud cover will limit heating
to some degree across the south today, so CAPE values do not look
very impressive. There is also a lack of shear, so no severe
weather is expected. The low level jet shifts into the eastern
Dakotas tonight, and the models differ slightly on where its best
focus will be. For this FA, the best potential will be across the
far south. The 500mb short wave also remains over the area, so
that will also help with forcing. Increased pcpn chances a bit
across the south, but confidence in higher pcpn amounts is not as
great. Went with a blended WPC/superblend solution to pcpn
amounts, which would favor a half an inch up to about an inch over
the southern FA today/tonight.

.LONG TERM...(Sunday through Friday)
Issued at 320 AM CDT Sat Aug 12 2017

Cloud cover and continued rain chances will continue into Sunday
and Sunday night, mainly across the southern FA. Once again, there
will be limited instability, so no severe weather is expected.
However still have the 500mb short wave moving through, so showers
and weak thunderstorms will continue across the south. Also raised
pcpn chances for this time frame, especially across the far south.
Total pcpn amounts for the entire today through Sunday night
period could range from 1 to 2 inches, but thinking the higher end
amounts will need slow moving or training storms. Dew point
values have struggled to reach past the upper 50s lately, and
precipitable water values stay on the lower end. The short wave
will finally exit the area by Monday, but the next system will
begin to affect the western FA by late Monday night.

Tuesday through Saturday...An upper ridge axis will exist over MN
on Tuesday morning, shifting eastward as an upper wave moves into
the area. A surface low will be moving eastward across the
Dakotas with a warm front likley lifting northward into the
forecast area. Showers and thunderstorms will accompany this
system and could produce heavy rain in some areas. The GFS slowly
moves the main upper trough through the area Wednesday and
Wednesday night, bringing more precipitation to MN during this
time. The ECMWF is more progressive and goes to a drier westerly
flow aloft by midday Wednesday. The current forecast is basically
a blend of the two solutions. Another wave may push through the
area on Thursday night and Friday. So, it looks like an active
week with a some good chances for precipitation. Also,
temperatures look to remain near to slightly below average with
highs generally in the mid 70s to low 80s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 120 PM CDT Sat Aug 12 2017

VFR cigs spreading across southern Red River Valley this aftn and
tonight with rain showers south of FAR. May see an isold TSTMS
vcnty FAR in the early evening hours but VFR outside of any
activity.

&&

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

$$

UPDATE...Speicher
SHORT TERM...Godon
LONG TERM...Godon/Knutsvig
AVIATION...Speicher



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