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FXUS63 KFGF 171731
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1231 PM CDT Tue Jul 17 2018

.UPDATE...
Issued at 1229 PM CDT Tue Jul 17 2018

No additional changes needed today.

UPDATE Issued at 1019 AM CDT Tue Jul 17 2018

Forecast on track. Diurnal CU developing in the far eastern
forecast area as expected as 500 mb temps remain cool enough.
A few CU psbl farther west into the RRV as well but temps warming
aloft will keep coverage small.

.SHORT TERM...(Today and tonight)
Issued at 240 AM CDT Tue Jul 17 2018

Surface high pressure is in place over our CWA and will slowly slide
east and southeast through tonight. Upper low over Hudson Bay will
also slowly transition east through these periods keeping colder air
mass in place and only a slight moderation from our west. Front
stalled just south of our CWA is shown to be possible focus for a
few sprinkles or light showers on high res guidance, but if this
happens it looks to remain out of our area due to much drier air in
place. From a temperature/sky cover standpoint I leaned towards
persistence as there will generally be very little change locally in
air mass (only a slight moderation in temps aloft tonight). CU field
may redevelop this afternoon in NW MN during peak heating in a
similar fashion as yesterday (just shifted eastward a little). Highs
temperatures should be in the 70s to just under 80F (coolest east),
and lows in the 50s (slightly warmer than this morning).

.LONG TERM...(Wednesday through Monday)
Issued at 240 AM CDT Tue Jul 17 2018

Satellite imagery early this morning reveals an upper level impulse
progressing eastward across the OR/ID/MT region. This shortwave is
expected to continue eastward over the northern Rockies today before
diving slightly southeastward on the eastern side of the upper level
ridge positioned over the southwestern CONUS. As this occurs, lee
cyclogenesis is expected across the western Dakotas/NE region on
Wednesday. Southerly winds induced by this feature and the surface
high positioned over the Great Lakes/Ohio river valley region will
allow for warm, moist air to return to the region and amplification
of the upper level shortwave. Afternoon highs in the mid to upper
80s are expected for Wednesday with increasing cloudiness throughout
the day.

Recent guidance suggests rain chances will gradually increase from
Wednesday evening through Thursday morning and continue through
Friday. Rain chances will initially be highest across southeast
ND/western MN but will gradually spread across the region during the
day Thursday and into Friday. With weak instability in place a few
thunderstorms can't be ruled out, but weak flow aloft due to the
proximity to the upper level low will hinder any potential for
severe weather. Both deterministic and ensemble guidance show broad
total QPF signals of 0.5-1 inch with higher local amounts possible
south of the Highway 2 corridor. However, given uncertainty in the
low track and where mid level frontogenetical banding may occur (as
suggested by the 00z GFS and NAM), confidence is low in exact
rainfall totals.

Calmer weather is expected leading into Saturday as surface high
pressure builds back into the region. Clearing skies should allow
afternoon temperatures to rebound into the low 80s. Rain and
thunderstorm chances return to the region Sunday night and into
Monday as a cold front pushes through the region. Decent model
agreement suggests relatively high confidence in these rain chances,
and deterministic guidance suggests a convective environment that
may support strong, possibly severe, thunderstorms. However, overall
confidence on severe thunderstorm potential is low due to
differences in model timing.

&&

.SHORT TERM...(Today and tonight)
Issued at 240 AM CDT Tue Jul 17 2018

Surface high pressure is in place over our CWA and will slowly slide
east and southeast through tonight. Upper low over Hudson Bay will
also slowly transition east through these periods keeping colder air
mass in place and only a slight moderation from our west. Front
stalled just south of our CWA is shown to be possible focus for a
few sprinkles or light showers on high res guidance, but if this
happens it looks to remain out of our area due to much drier air in
place. From a temperature/sky cover standpoint I leaned towards
persistence as there will generally be very little change locally in
air mass (only a slight moderation in temps aloft tonight). CU field
may redevelop this afternoon in NW MN during peak heating in a
similar fashion as yesterday (just shifted eastward a little). Highs
temperatures should be in the 70s to just under 80F (coolest east),
and lows in the 50s (slightly warmer than this morning).

.LONG TERM...(Wednesday through Monday)
Issued at 240 AM CDT Tue Jul 17 2018

Satellite imagery early this morning reveals an upper level impulse
progressing eastward across the OR/ID/MT region. This shortwave is
expected to continue eastward over the northern Rockies today before
diving slightly southeastward on the eastern side of the upper level
ridge positioned over the southwestern CONUS. As this occurs, lee
cyclogenesis is expected across the western Dakotas/NE region on
Wednesday. Southerly winds induced by this feature and the surface
high positioned over the Great Lakes/Ohio river valley region will
allow for warm, moist air to return to the region and amplification
of the upper level shortwave. Afternoon highs in the mid to upper
80s are expected for Wednesday with increasing cloudiness throughout
the day.

Recent guidance suggests rain chances will gradually increase from
Wednesday evening through Thursday morning and continue through
Friday. Rain chances will initially be highest across southeast
ND/western MN but will gradually spread across the region during the
day Thursday and into Friday. With weak instability in place a few
thunderstorms can't be ruled out, but weak flow aloft due to the
proximity to the upper level low will hinder any potential for
severe weather. Both deterministic and ensemble guidance show broad
total QPF signals of 0.5-1 inch with higher local amounts possible
south of the Highway 2 corridor. However, given uncertainty in the
low track and where mid level frontogenetical banding may occur (as
suggested by the 00z GFS and NAM), confidence is low in exact
rainfall totals.

Calmer weather is expected leading into Saturday as surface high
pressure builds back into the region. Clearing skies should allow
afternoon temperatures to rebound into the low 80s. Rain and
thunderstorm chances return to the region Sunday night and into
Monday as a cold front pushes through the region. Decent model
agreement suggests relatively high confidence in these rain chances,
and deterministic guidance suggests a convective environment that
may support strong, possibly severe, thunderstorms. However, overall
confidence on severe thunderstorm potential is low due to
differences in model timing.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1229 PM CDT Tue Jul 17 2018

VFR thru the pd. Scattered CU field mainly nrn RRV and over NW MN
will dissipate late aftn/eve with a mainly clear sky
tonight. Increasing clouds Wednesday from the southwest, mainly
cirrus thru 18z into SE ND. Light and variable winds today turning
a more consistent south Wednesday.

&&

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

$$

UPDATE...Riddle
SHORT TERM...DJR
LONG TERM...AM
AVIATION...Riddle
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