Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 190359

Area Forecast Discussion
National Weather Service Grand Forks ND
1059 PM CDT Sun Aug 18 2019

.SHORT TERM...(This evening through Monday)
Issued at 234 PM CDT Sun Aug 18 2019

Afternoon surface observations show a surface high over central
SD and a surface low in the vicinity of Hudson Bay that are inducing
westerly winds across the region. Daytime heating through the day
will allow temperatures to continue to warm into the mid 70s with
adiabatic downslope warming allowing some locations to reach into
the upper 70s in the northern Red River Valley. Daytime heating
is also steepening low level lapse rates, favoring downward
momentum transfer of 20-25 knot 850 mb winds to the surface - as
evident by gusty winds across the northern Valley. These gusty
winds will continue until around sunset when radiational cooling
will drive boundary layer decoupling.

The surface high over SD will shift eastward tonight following
behind weak cold advection over the Great Lakes and height rises
behind an associated upper level wave. This will allow southerly
winds to bring a warmer/moist airmass back into the region overnight
tonight and into the day Monday. Despite radiational cooling, the
warm advection will help keep temperatures in the mid 50s. A
diffuse surface trough noted in surface observations across north
central MT will propagate eastward overnight and, aided by
isentropic lift along the axis of an H850 thermal ridge, may bring
a few light rain showers to the international border region late
tonight. However, recent hi-res guidance suggests showers should
remain on the Canada side of the border, so no categorical pops
are included in this forecast issuance.

As warmer air returns to the region tomorrow, temperatures will
climb into the low to mid 80s with dewpoints in the 60s spreading
northward through the day. The continued eastward advection of a
mid level thermal ridge will help build a capping inversion over
the region that will maintain dry weather for the day Monday.

.LONG TERM...(Monday night through Sunday)
Issued at 234 PM CDT Sun Aug 18 2019

Monday night and Tuesday...A shortwave trough moving through
southern Canada and surface low/cold front moving through the Red
River Valley will bring an increased chance of precipitation.
Strongest upper forcing will be to the north and with not much low
level jet we will have to see how well storms can sustain themselves
Monday night. However, it does look there will be at least some MU
CAPE and even drier model solutions have some precip in the north
closest to the upper wave. Have POPs mostly in the north and west
Monday night, with some lingering showers in the northeast into
Tuesday morning as the cold front pushes through. The front will
also knock temps back into the 70s for Tuesday.

Wednesday through Friday...Warming trend returns for mid to late
week as pretty progressive flow shifts northwesterly flow aloft to
brief ridging and then another shortwave. Surface high will move
east and temps will warm back towards seasonal averages. There will
be another chance for precipitation Thursday night into Friday as
the next shortwave moves into the area.

Saturday and Sunday...Model solutions diverge with no strong signal
for timing of various shortwaves in the continued progressive
pattern. Will keep things fairly seasonal with temps near average
and some low chances for precipitation.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1053 PM CDT Sun Aug 18 2019

VFR CIGs prevail at all TAF sites through the period. We could see
an isolated shower or two along the International Border tonight
with otherwise quiet conditions across the region. Added LLWS
toward sunrise Monday at KGFK, KTVF, and KFAR. Mid to high clouds
are expected to gradually increase through the mid afternoon
through early evening Monday.




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