Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 200239

Area Forecast Discussion
National Weather Service Grand Forks ND
939 PM CDT Mon Jun 19 2017

Issued at 934 PM CDT Mon Jun 19 2017

Adjusted POPs for line of showers/storms east of the valley moving
SE at 35 kts...which exits them from ern CWA bndry around 07Z to
09Z timeframe. Similar speed/motion for line of storms in NE NODAK
will arrive into Grand Forks area in the 10 PM to 11 PM timeframe
and hi-res guidance has them diminishing as they move across the
valley into MN. Will go with that idea and extend if needed. Still
seeing 30 to 40 mph winds with storms and believe they will remain
well sub-severe as CIN increases across region as activity to east
has already transitioned to primarily SHRA.

UPDATE Issued at 637 PM CDT Mon Jun 19 2017

Line of rain showers and thunderstorms along a Pembina-Forest
River-Petersburg-New Rockford line will continue moving SE across
the forecast area this afternoon. At the current time the main
threat with this activity is winds generally in the 35 to 40 mph
range but some gusts up to 45 mph are possible. DCAPE gradient
vcnty of Hallock is tightening so will be monitoring for some
higher winds in the northern valley but expecting storms to stay
sub-severe. Have removed POPs behind the line however last few
radar scans are showing re-development NW of Turtle Mtns in SW MB.
Will monitor and adjust POPs again if needed, but with loss of
solar expecting activity to weaken...which is supported by an
increase in MLCIN shown on latest SPC Mesoanalysis.


.SHORT TERM...(This evening through Tuesday)
Issued at 308 PM CDT Mon Jun 19 2017

Challenge will be coverage of convective activity this evening as
a potent short wave approaches the FA from the NW. Line of
convection approaching the FA from southern Manitoba will be
watched for down bursts winds and hail. Given meager ML CAPE
values 250 to 500 J/kg combined with strong shear, 30 to 40kts
effective will have storms with marginally severe hail and wind
capability. Wave will quickly translate to the southeast with
activity diminishing rapidly in the 7 to 9pm time frame. Rain
totals will be on the low side except for under the stronger
echoes. Generally less than a tenth for most with up to a quarter
possible under the stronger storms.

Overnight winds will lighten and where skies clear out the
possibility for some patchy fog will develop especially over areas
that receive the higher amounts of rain. Full sun will quickly
erode any fog and temps will rise into the 70s for most areas
Tuesday afternoon. Light north winds with SFC high pressure
gradually moving into the FA during the afternoon.

.LONG TERM...(Tuesday night through Monday)
Issued at 308 PM CDT Mon Jun 19 2017

On Tuesday night, surface high pressure departs eastward and an
upper level ridge rushes through. Cloud cover and rain chances will
increase in eastern North Dakota overnight into Wednesday morning as
a shortwave moves in. At this time, expect an initial round of
showers Wednesday morning in the Devils Lake area with this
shortwave, then mid day/afternoon development of showers and
thunderstorms forced by the cold front that will move through in the
afternoon and evening, eventually moving out of northwest/west
central Minnesota Wednesday night. Favorable convective ingredients
include strong effective 0-6 km bulk shear of 50-60 kts, dew points
in the upper 50s to middle 60s, precipitable water values near 1
inch, and perhaps some 850 mb jet forcing, but morning showers and
cloud cover will likely limit instability, especially in the north.
There is still model disagreement on which areas will be able to
recover, but the NAM and GFS do indicate potential for moderate
instability with MUCAPE values maxing out at 2000-3000 J/kg in the
southern half of the forecast area. Scattered thunderstorms on
Wednesday will have the potential to become strong to severe with
these ingredients. Expect any severe thunderstorms during this
timeframe to have main threats of large hail and damaging winds.

On Thursday, the upper low associated with Wednesday`s system churns
through Manitoba and into Ontario. Weak shortwave energy, combined
with a strong 850 mb jet, will bring small chances for showers to
the northern half of the area Thursday and Thursday night, but
moisture is quite limited as we remain in northwest flow aloft. Of
greater impact on Thursday will be breezy west winds with gusts to
35 mph in the Devils Lake basin region.

For Friday through the weekend, a more active northwest flow pattern
and weak upper level waves moving through will perhaps yield some
showers and storms in the area on and off. The better rain chances
are associated with a shortwave moving through Friday night and
Saturday. That being said, the weekend doesn`t look to be a wash out
by any means, and heavy rain or severe storms are not anticipated at
this time.

Expect Wednesday to be the warmest day through next weekend with
highs reaching the 70s in the north to the 80s in the southern Red
River Valley. For the end of the week through the weekend, highs
will be in the 60s to middle 70s, with lows in the 40s to 50s.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 637 PM CDT Mon Jun 19 2017

Line of SHRA/TSRA will move through GFK-TVF over next couple of
hours and FAR-BJI toward mid-evening. Expecting no activity behind
the line...which should impact sites for no more than 45 to 60 min
as they move through. Clearing behind line may cause some patchy
fog tomorrow morning as NW winds decrease, but not enough
confidence spatially to mention in TAFs at this time.




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