Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 242038

Area Forecast Discussion
National Weather Service Grand Forks ND
338 PM CDT Thu May 24 2018

.SHORT TERM...(This afternoon through Friday)
Issued at 337 PM CDT Thu May 24 2018

Negatively tilted trough over western ND and southwest MN will
transition along the International Border and east of our CWA
Friday morning, followed by another shortwave trough through
southern Manitoba Friday afternoon. There is already shower
development west of our CWA closer to the upper low center/cold
pool, but over our CWA there is is an axis of subsidence/dry slot
limiting potential over much of our area.

Forcing increases through the weekend, with approaching weak cold
front acting as focus for convergence/thunderstorm initiation
this afternoon/evening. Next moisture plume will transition back
over our CWA, and we should see destabilization ahead of cold
front as it shifts east. Some convective allowing models support
line of thunderstorms developing in our west after 23Z (6PM) and
transition eastward ahead of cold front. There are other models
showing much less coverage, and with current period of stability
it could limit potential if recovery doen`t occur as advertised.
ML CAPE is still advertised to increase once again in ND to 1500
J/KG (or higher) range and while shear is marginal to weak this
would support strong to severe thunderstorm development.

Very warm/hot temperatures are expected again as westerly flow
transitions back over our CWA and WAA redevelops as surface low
pressure redevelops. Thunderstorm chances may remain in Canada,
but there is at least a weak precip signal in our far north as
shortwave passes over southern Manitoba, and a stalled
boundary/front lingers near the International Border. There could
be a narrow axis of instability along this frontal zone, so while
severe threat would be isolated, a few stronger storms can`t be
ruled out.

.LONG TERM...(Friday night through Thursday)
Issued at 330 PM CDT Thu May 24 2018

Sat-Sun: Surface ridge moves over the region Saturday allowing hot
temperatures to develop both Saturday and Sunday. Hottest
temperatures into the mid 90s will reside in the lower Red River
Valley both afternoons. Clouds from low pressure lingering within
southwest Ontario will result in lower high temperatures into the
80s within far northwestern Minnesota on Saturday. There will be a
chance of overnight thunderstorms within southeastern North Dakota
as a nocturnal low level jet pushes better theta-e content within
South Dakota over a northward moving effective warm front.
Convection should dwindle Sunday morning allowing for dry conditions
through the majority of the day Sunday as well as strong
insolation/warming. While the effective warm front moves north, a
cold front also moves southward out of Canada. These two boundaries
meet and stall over the region to create additional thunderstorm
chances late Sunday lasting through the overnight hours.

Mon-Thu: Things get a little plugged up early next week with the
stalled front lingering over the region Memorial Day through
Tuesday. This will produce shower and thunderstorm chances both
days. Recent trends in guidance and markedly increased rain chances
for Memorial Day. Increased thicknesses over the region will also
keep temperatures warmer with Memorial Day highs still capable of
reaching into the 80s. Strength of thunderstorms will depend on how
much heating can be attained both days battling cloud debris.
Overnight convection remains possible Memorial Day and Tuesday
nights again attributed to nocturnal low level jet formation. Rain
chances are also linked to a surface low in western South Dakota
progged to move into the region along the stalled front. There are
still many questions regarding severe potential as better wind shear
comes in proximity with the surface low towards Tuesday, but may not
be fully understood until the day of or night before. Come
Wednesday, the surface low is expected to be northwest of the region
although rain chances remain on the back side of the low.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1244 PM CDT Thu May 24 2018

VFR conditions should prevail across eastern ND and northwest MN,
with reductions possible where thunderstorm activity occurs. Early
in the TAF period a line of showers/thunderstorms (some strong)
will continue to transition eastward (impacting KBJI). Another
round of thunderstorms should develop by 23-00Z over eastern ND,
transitioning eastward through the evening (strong/severe
possible). Gusty winds should diminish this evening, though
through the afternoon there may be some gusts 25-30kt possible
(mainly in the Red River Valley).




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