FXUS63 KFGF 250007

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

Issued at 703 PM CDT Thu May 24 2018

500 mb low moving NE thru SW Manitoba at 00z with best forcing for
storms in Manitoba. Drier airmass still over much of eastern ND
and this is preventing much CU from getting going, the exception
is on eastern edge of deeper moisture on SE side of Manitoba upper
low, which has helped a few showers/tstorms go over far NW fcst
area Langdon/Cando but they have quickly moved into Canada. Also
far SE ND and WC MN where some deeper moisture via water vapor is
showing from E SD into SE ND/WC MN and this has allowed a few
storms to fire in this area. Weak bulk 0-6 km shear has meant they
are having a hard time growing, sustaining themselves. The mid RRV
around Grand Forks is in the limited cape region per mesoanalysis
with capes 500 j/kg so it may very hard pressed to get anything
going in the mid RRV. Will tone down chances a tad to mostly
isold/slight chc


.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 00Z TAFS through 00Z Friday evening)
Issued at 703 PM CDT Thu May 24 2018

VFR thru the pd...except near any storm this eve. Winds will shift
from a more southerly direction to a more westerly direction
overnight into Friday as a trough moves east.




Back to Main Forecast Discussion Page