Scientific Forecaster Discussion
fxus63 kfgf 180249
Area forecast discussion
National Weather Service Grand Forks ND
949 PM CDT Sat Aug 17 2019
issued at 944 PM CDT Sat Aug 17 2019
Any lightning has moved east or south of the area with a few
lingering showers remaining. These should end over the next few
hours with a dry overnight and day setting up for Sunday.
Update issued at 646 PM CDT Sat Aug 17 2019
Line of convection continues to move east across the Minnesota counties
stretching from waskisk to Detroit Lakes to near Wheaton. Will
continue to see a mostly sub severe storm wind threat with an
occasional 60mph severe gust possible as storms push to the east
the remainder of the evening. Strongest instability exists in
areas mainly from Grant co and southwards so did include Grant in
Severe Thunderstorm Watch with more organized convection moving
into the area from the west.
Short term...(this evening through Sunday night)
issued at 303 PM CDT Sat Aug 17 2019
Convection timing and strength tonight will be the main
challenges for the period.
Showers and thunderstorms that initially went up along the surface
trough axis this morning have mostly moved off to the east and
weakened, and there has been some decent sunshine and heating out
ahead of the main shortwave and cold front that is entering the
western County Warning Area this afternoon. Storm Prediction Center mesoanalysis Page has ml cape of
1500-2000 j/kg with not much cin left over our southwestern
counties. Deep layer bulk shear is not huge at around 25-35 kts,
but still adequate and the shear should improve as the shortwave
comes into our area. Web cams of the cumulus field west of Fargo
show not much vertical development yet, and day cloud phase rbg
curve is mostly liquid in that area. However, further north in
western Grand Forks County, there is a bit more vertical
development of cumulus starting and even the Fargo cu field has
started to improve. The more recent hrrr runs have some
convective initiation in that area, so might not be a bad first
guess. Will continue to keep an eye on developing storms and
should start to see more activity in the next few hours.
At this point it seems cells going up are rather isolated but
with mean wind close to the orientation of the cold front, that
may not last very long. Cams seem to show the first initiation
around gfk moving eastward into Minnesota with a bigger convective
complex of thunderstorm clusters later this evening possible.
This does not seem completely out of the question and some quarter
inch hail and wind gusts to 60 mph will be possible mainly in
southeastern ND and western Minnesota. Heavy rain could also be an issue
in some areas as precipitable water values are around 1.2 inches but there could
be some training echoes along the boundary. There is good
agreement on the frontal boundary and the showers and storms
pushing east of our counties around 09 to 10z tonight, with most
of our area going dry by morning. Some clearing in the
northwestern counties could drop temps down below 50 degrees.
Sunday should be dry with cooler temps mostly in the upper 60s to
mid 70s even with sunshine. Winds will pick up out of the
southwest Sunday night ahead of the next trough, and temps should
stay in the 50s with decent mixing.
Long term...(monday through saturday)
issued at 303 PM CDT Sat Aug 17 2019
Scattered thunderstorms will be possible again during the overnight
hours Monday into Tuesday with quieter weather likely for middle
part of the work week. Rain and storm chances pick up again heading
into the upcoming weekend.
Monday through Monday night...
Long and medium range deterministic and ensemble guidance is in
fairly good agreement in the chance for thunderstorms late Monday
into early Tuesday. Guidance depicts zonal flow over the northern
rockies inducing Lee troughing over eastern Montana/western ND through
the day Monday. Higher Theta-E air will advect northward into the
region in response to the Lee troughing and will support at least
moderate levels of instability by late Monday. A 50-70 knot mid
level jet over southern Canada will support enough deep layer shear
to introduce the potential for a few strong to severe storms.
Thunderstorms will likely develop by the evening hours as an
eastward advancing cold front pushes through the region.
Tuesday through Wednesday...
High pressure is expected to build into the region in the wake of
Monday night's cold frontal passage. Temperatures during this period
will be slightly below seasonal normals with highs in the mid to
upper 70s for Tuesday and Wednesday.
Thursday through Saturday...
Long range guidance is again in reasonable agreement about the
approach of an upper level shortwave from the Pacific northwest into
the northern plains Thursday into early Friday. The approach of this
wave (and attendant surface low) and eastward exit of the surface
high will induce breezy southerly return flow through the plains
that will allow temperatures to warm slightly into the upper 70s and
low 80s for Thursday afternoon. Showers and thunderstorms will be
possible along a cold front as it moves eastward through the region.
However, it should be noted that difference between guidance gives
low confidence regarding the timing of precip during this
After this period, divergence in model solutions throws uncertainty
into the extended forecast. However, the general trend is that
nearly zonal mean flow aloft will continue to allow shortwave
troughs to quickly propagate through into the region and bring
periodic rain/thunderstorm chances heading into the weekend.
Aviation...(for the 00z tafs through 00z Sunday evening)
issued at 646 PM CDT Sat Aug 17 2019
Line of storms will impact bji over the next 2 hours. After that
the taf period looks to be mostly VFR with west to northwest winds
at 5 to 15kt with gusts tomorrow afternoon around 20kts. There is
some guidance bringing in MVFR cigs for a brief period tonight at
tvf and bji. Will monitor before including in the next set of