751
FXUS63 KFGF 101444
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
944 AM CDT Wed Jul 10 2024

.KEY MESSAGES...

- Risk for heat related impacts Friday through Sunday.

- Chance for thunderstorms return Friday night and Saturday
  night.

&&

.UPDATE...
Issued at 944 AM CDT Wed Jul 10 2024

Water vapor imagery indicates the upper low across southern
Minnesota continuing to propagate away from our region, with
ridging building across the western CONUS, and surface ridging
building into the northern plains. Satellite imagery shows
elevated smoke lingering across the region, although visibility
is P6SM across the CWA so smoke is elevated which will limit impacts
due to the smoke. Visibility is lower across central North
Dakota, and HRRR smoke forecast is doing fairly well with the
forecast - and keeps these higher impacts to the west of our
CWA. All in all forecast on track and impacts minimal today.

UPDATE
Issued at 719 AM CDT Wed Jul 10 2024

Patchy ground fog Cando area to just west of Devils Lake but
conditions improving. Rest of the area mainly clear. No changes
to forecast or thoughts for the day.

&&

.DISCUSSION...
Issued at 332 AM CDT Wed Jul 10 2024

...Synopsis...

Ensemble guidance supports building 500 mb heights into the
region today into Thursday. Friday and thru the weekend, several
500 mb short waves moving east thru Canada will help suppress
the ridge and make flow aloft more zonal or even west-northwest
by Sunday. These short waves are mot notable Friday night and
Saturday night when chances for thunderstorms increase. Also
temps peak this weekend before falling back early to mid next
week.


Today and Thursday..

The building 500 mb ridge will suppress the daily development
of afternoon thunderstorms, with chances today confined to
eastern and southern Minnesota. Some CU development this aftn
but expect minimal coverage then clear tonight into Thursday.
HRRR, RAP and firesmoke.ca smoke forecasts indicate the same or
even a tad less high level smoke today and Thursday as winds
aloft turn more southwest. For forecast collab purposes did
mention some patchy smoke in the western fcst area against
Bismarck as that area maintains unhealthy AQI this morning
before improvement. Moderate elsewhere. Hazy sun anticipated
today, but sun will remain strong enough to push temps to or
just above national blend of models forecast values. Each day in
the past 3 days, highs have been higher than fcst by 1-3
degrees in many areas, most noticeable in the Red River valley.
Thus used a 50/50 blend of NBM/NBM75 for highs today. An
increase of around 2 degrees above strict NBM.


...Risk for heat related impacts this weekend...

As the upper ridge builds across the western CONUS and gradually
shifts east a much warmer and moist airmass propagates across
the region, especially Friday through Sunday. NBM MaxT 25-75
percentiles range from ~90F to ~98F during this period (across
the southern CWA at least), and with crops nearing peak
Evapotranspiration Td each day should be ~70F. Heat index values
would be >100F if the temperatures were able to reach upper 90s,
but that is still a low probability outcome. At this point most
likely (80% chance) heat index values each afternoon will be in
the mid to upper 90s, which is below advisory criteria. However,
the new NWS heat risk product (which accounts for duration of
heat including both daytime and nighttime temperatures as well
as if those temperatures pose an elevated risk of heat related
impacts based on data from the CDC) indicates a moderate risk
of heat related impacts Friday into Saturday with a major risk
of heat related impacts on Sunday. Slightly cooler air moves in
early next week.

www.wpc.ncep.noaa.gov/heatrisk

...Chance for thunderstorms return Friday night and Saturday
night...

One of several short waves and associated low pressure systems
and fronts will move thru central Canada Thursday sending a
weakening front south toward southeast Saskatchewan and western
Manitoba Thursday night. Instability remains highest in west
central Manitoba and thus anticipate better storm chance north
of the border in that area. There are some low pops into north
central ND in case any storms from the northwest move in. If
they do they will be on a weakening trend.

Friday will see another short wave move east a bit farther south
than the prev one on Thursday with short wave moving central
Manitoba Friday afternoon and a cold front/trough dropping
toward the US/Manitoba border Friday evening and overnight. Mean
ensembles indicate probs more than 40 percent of having surface
CAPEs greater than 3000 j/kg in southern Manitoba and south thru
eastern ND into northeast SD 00z Sat. 0-6 km bulk shear remains
fairly weak (20-30 kts) but instability high and mean CIN in
eastern ND in less than 100 j/kg suggest thunderstorm threat,
possibly severe, is present. Day 3 from SPC indicates this
possibility of MCS may develop and move southeast thru the Upper
Midwest Friday night but still a bit too uncertain yet for
severe outlook.

CSU machine learning indicate that another chance for storms and
possibly severe weather exists Saturday night over E ND and thru
MN southeast toward Chicago. Sunday CSU machine learning progs
indicate that severe weather threat more southeast MN into Ohio.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 944 AM CDT Wed Jul 10 2024

VFR conditions throughout the TAF period with surface high
pressure building into the region.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.

&&

$$

UPDATE...TG/Riddle
DISCUSSION...Riddle
AVIATION...MM/TG