360
FXUS63 KFGF 201730
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1230 PM CDT Sat Jul 20 2024

.KEY MESSAGES...

- Daily shower and thunderstorm chances through the period.
  Severe weather unlikely.

&&

.UPDATE...
Issued at 1220 PM CDT Sat Jul 20 2024

Signs of convection are starting to present itself over the Lake
of the Woods area. Biggest uncertainty is still the timing of
thunderstorm activity with this thick layer of smoke aloft.
Latest report was from the grand forks airport that had the
smoke up to 5000ft. However thoughts are still thinking
thunderstorm development to start around 21z at the earliest.

UPDATE
Issued at 1013 AM CDT Sat Jul 20 2024

Morning light on visible satellite reveals widespread, thick
smoke aloft around much of the Northern Plains and southern
Canada. Weak winds aloft keeps confidence high in this smoke
will linger through the day. This will have an influence on our
daytime temperatures by slowing diurnal heating and tampering
maximum temperatures some.

During this update, leaning on CAMs that include affects from
smoke like HRRR/RAP, both of which still reach convective
temperatures progged to be around 85 this afternoon. However,
these guidance start thunderstorm development later than some
other guidance, likely owing to the influence of smoke. Adjusted
PoPs a bit to delay the start of isolated to scattered
thunderstorms into the 3pm-5pm timeframe, ending between
8pm-10pm. The exception to this may be in lakes country of
west-central Minnesota where smoke is thinnest leading to
earlier initiation of storms.

Lack of shear today coupled with marginal but sufficient
instability (MLCAPE 1000-2000 J/kg) lends high confidence in
today`s storms being unorganized, pulse-type thunderstorms
depositing outflow boundaries that kick off subsequent
thunderstorms. Main hazards from this type of activity will be
lightning and gusts 40-50 mph in relatively stronger storms.

UPDATE
Issued at 625 AM CDT Sat Jul 20 2024

Mostly quiet weather prevails this morning across much of the
area, with only isolated shower activity in west-central
Minnesota. Temperatures are generally in the low to middle 60s
with light and variable winds.

&&

.DISCUSSION...
Issued at 253 AM CDT Sat Jul 20 2024

...Synopsis...

Current water vapor imagery nicely showing an upper level trough
over the intersection of Minnesota, South Dakota, and North Dakota.
Satellite shows some clouds over the FA, High confidence in lack of shear to organize thunderstorms puts
confidence high in expecting thunderstorms to be mainly in the
southern Red River Valley and MN Lakes country associated with
this low. Northwest flow is here to stay for the majority of the
forecast period, flattening to more westerly to end the week.
Temperatures will be in the 80s through the work week, possibly
warming into the low 90s as the UL ridge gets compressed before
flattening.

...Daily Precipitation Chances...

With the northwest flow, shortwaves are increasingly common in the
mid levels. These shortwaves will bring numerous rounds of
precipitation chances through mid-week, with shower and thunderstorm
chances somewhere in the FA every day between now and then. With
most of these, moisture is lacking to even get a quarter of an inch.
However, Monday into Tuesday morning, WSUP Probabilities are 20 -
30% around the international border for greater than or equal to a
quarter inch of precipitation. With these precipitation chances,
severe chances are very low (less than 5%) with any of these weak
systems that transit the area.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1220 PM CDT Sat Jul 20 2024

VFR conditions throughout the TAF period with the exception of
vicinity thunderstorms. Looking at satellite the thick smoke
aloft covers all the TAFS sites. According the latest PIREPs the
smoke layer stops at 5000 ft so that is represented in the TAFS
as the SCT layer. The smoke layer may also delay thunderstorm
development to create more uncertainty but still thinking after
21z scattered thunderstorms may pop up until 0300 to 06z.

&&

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

&&

$$

UPDATE...CJ
DISCUSSION...AH
AVIATION...MM