Area Forecast Discussion
Issued by NWS Grand Forks, ND

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997
FXUS63 KFGF 222349
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
649 PM CDT MON AUG 22 2016

.UPDATE...
Issued at 644 PM CDT Mon Aug 22 2016

Forecast challenge for tonight will be potential for convection
developing along I 94 in the late evening hours. Appears a cell
tried to develop north of Devils Lake and growth was quickly
limited with 12 to 14 deg H700 temp cap. Experimental HRRR had
developed activity by 03Z over the Valley City area, where alto cu
evident on latest satellite image. Appears potential certainly is
there however the mid level cap will be a player. Will continue
thinking of low POPs for the tonight period. No grid changes
planned.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 310 PM CDT Mon Aug 22 2016

Main forecast challenge will be tstm chances tonight into Tuesday.
As of 3 pm skies remained clear although there was some smoke
drifting into western ND. Wind speeds remained a little gusty from
the south too. Looking ahead into tonight, think most of the
evening will be very nice. Models begin to crank up the low level
jet into east central ND in the 03z-06z Tue time frame, then
slowly lift it NNE overnight. However, models do differ on
whether this will be enough to generate isolated showers and
tstms. SPC HRRR develops showers/tstms in the 00z Tue time frame,
which seems way too fast. Prefer the exp HRRR which develops
echoes in the 05z-06z Tue time frame and lifts these slowly NNE.
This also resembles the 12z GFS20 and forecast continuity.

So will go with the idea of isolated convection initiating in the
late evening time frame over east central ND and lifting into the
northern Red River Valley and NW MN by morning. These models
eventually lift most of this activity into southern Canada or east
of the FA, so most of Tue morning dries out again. Question then
turns to additional tstm development along the cold front, which
moves into the Red River Valley region Tue afternoon. SPC Day2
severe weather outlook has most of the FA in a marginal risk.
Limiting factors appear to be the amount of moisture return and
the best shear lagging behind the front. Thermal recovery could
also depend on how fast any showers and tstms exit the FA Tue
morning too. So some uncertainty yet, which is why the SPC
outlook is only marginal.

.LONG TERM...(Tuesday night through Monday)
Issued at 310 PM CDT Mon Aug 22 2016

Main challenge will be periodic precipitation chances throughout the
period.

Models continue to be in pretty good agreement regarding the timing
of Tuesday`s cold front and associated precipitation. The front
should be near the Red River Valley to start the period and push
east of the area in the 06-09z time frame Wednesday morning.
Although instability begins dropping off, storm chances will persist
along and ahead of the front as a 35-40 kt low level jet kicks in
across northern Minnesota late in the evening and early overnight.
The front and its associated forcing should clear the eastern
forecast area near daybreak Wednesday.

Behind the front, temperatures will be much cooler with highs in the
mid to upper 60s across the Devils Lake basin with mid 70s
everywhere else for Wednesday. It will feel even cooler as high
pressure building into the northern Rockies will create a decent
gradient across the region with northwesterly winds of 20-25 kts
west of the valley and 10-20 kts elsewhere. As the 500 mb low passes
just north of the international border, additional shower/storm
chances will persist throughout the day across the extreme north.

As the upper low pulls away on Thursday, the region will transition
to more zonal flow with several chances for embedded short waves.
The strongest appears to pass through on Friday and linger into the
first half of the weekend. Additional weak waves will be possible
for Sunday and Monday even as weak ridging builds in to the central
CONUS.

After Wednesday`s cooldown, temperatures will gradually moderate
each day throughout the period with the return of seasonal norms
by late in the weekend.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 644 PM CDT Mon Aug 22 2016

VFR however a cold front will move across the region and result in
a sharp change in wind direction from S to WNW tomorrow aftn.
Still too low of confidence for coverage/placement of resultant
TSRA activity for mention in TAF, but can expect SCT TSRA across
the valley region tomorrow afternoon.

&&

.FGF Watches/Warnings/Advisories...
ND...None.
MN...None.
&&

$$

UPDATE...Speicher
SHORT TERM...Godon
LONG TERM...Lee
AVIATION...Speicher



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