Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 232024

Area Forecast Discussion
National Weather Service Grand Forks ND
324 PM CDT Wed May 23 2018

.SHORT TERM...(This afternoon through Thursday)
Issued at 323 PM CDT Wed May 23 2018

Several weak embedded impulses withing southwest diffluent flow
will lead to periods of showers and thunderstorms over the next
few days, with a stronger shortwave trough Thursday through
Thursday night. Moist plume has resulted in higher PWAT values
over our CWA in the 1.2 to 1.5 range and this will support locally
moderate or heavy rainfall with some activity. Convective
allowing models indicate potential complex/cluster forming
southwest of our CWA and tracking northeast mainly along/south of
Highway 2 likely associated with period of increasing WAA and LLJ
development. Instability increases this evening and ML CAPE should
be in the 1500-2000 J/KG range and while shear will be limited we
should see potential for some stronger updrafts. Due to limited
shear profiles "pulse" type thunderstorm activity would be favored
with hail/wind main concerns this evening.

Forcing may be stronger on Thursday and axis of instability may be
in place early in the afternoon allowing for possible convective
development during the afternoon and increasing coverage through
Thursday evening. Shear may once again be the limiting factor,
but severe potential may be better from a coverage stand point
(hail/wind still favored threats).

Hot temperatures during the day and mild temperatures at night
are expected with unseasonably warm air mass established over the
region (cloud cover/precip will be wild card on temps). Many
locations will be near 90F across the RRV and mid to upper 80s
elsewhere. Lows will tend to be in the upper 50s and 60s.

.LONG TERM...(Friday through Wednesday)
Issued at 307 PM CDT Wed May 23 2018

On Friday morning, expect remnant showers and storms from overnight
activity to be exiting northwest MN to the east. Later Friday and
Friday night, surface troughing in the vicinity coinciding with a
shortwave propagating through the region will allow for additional
shower and storm development. Chances for organized stronger storms
are fairly low due to marginal deep layer shear and stronger forcing
having moved eastward out of the area, but decent instability
remaining in the region indicates some potential for a few stronger
storms to develop. Rain chances will taper off from west to east
Friday night, persisting into early Saturday for north central MN
and the Lake of the Woods region.

A hot and mostly dry weekend ahead will kick off the unofficial
start to summer, with high temperatures near record levels Saturday
and Sunday. A strong upper ridge will progress east from the Rockies
into the Plains Friday through Sunday night. Persistent dry air
aloft and surface high pressure across the Northern Plains during
this period will allow for abundant sunshine and fairly large
diurnal temperature swings. Expect daytime high temperatures in the
80s to lower 90s and overnight lows in the 50s and 60s each day.
Despite temperatures well above seasonal averages, humidity values
will be fairly low and winds light.

Monday through Wednesday, summer like temperatures continue with a
wetter weather pattern setting up. The previously mentioned upper
ridge builds eastward out of the Plains and an approaching system
brings chances for showers and thunderstorms each day.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1232 PM CDT Wed May 23 2018

VFR conditions should prevail through the TAF period, though
brief restrictions in vis/cig to MVFR (or even IFR) can`t be ruled
out if moderate/heavy rain were to impact a terminal. Shower and
thunderstorm activity should increase in coverage through the
afternoon, with best chance for impacts to terminals in the
evening. Currently best chance for thunderstorm impacts would be
outside of the first 6 hours, and with lower confidence on
thunderstorm coverage during that period I decided against VCTS
or TSRA mention in TAFs at this time. Southeast winds may gust
during daytime periods in the 20-30kt range (mainly at KFAR and
KDVL). A period of low level wind shear may also develop (mainly
at KBJI).




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