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Area forecast discussion 
National Weather Service Grand Forks ND
643 am CDT Thursday Jul 24 2014

Update...
issued at 643 am CDT Thursday Jul 24 2014

There is an intimidating line of thunderstorms marching across
North Dakota this morning. Model guidance is no help as to how
this line will evolve over time...and will need to use experience.
Instability axis remains across the western Dakotas...and
transitions to a stable airmass across eastern North Dakota.
Thus...anticipate that this line of storms will begin to weaken
in the next hour or two...and although remnants will make it into
this forecast area...it will be much weaker. The current 20-30 probability of precipitation for later
this morning should still get this point across. The main idea
that the best chance for thunderstorms will be after sunset still
seems the most reasonable.

&&

Short term...(today through friday)
issued at 345 am CDT Thursday Jul 24 2014

A stable airmass remains across the forecast area...with moderate to strong
instability located across the western Dakotas. Not much change
expected through the day. There is a stronger shortwave that will
ride over the upper ridge and into the forecast area later this morning. Any
associated activity will be moving into a stable airmass...with
dissipating convection possible across eastern North Dakota. Will
cover this precipitation chance with 20-30 probability of precipitation (following mainly the
hrrr guidance)...and will add more detail with the 7am update.
Otherwise...much of the day and evening will be dry. The best
chance for thunderstorms will be overnight (likely after midnight)
as convection from the west (initiated by a cold front/surface trough)
moves into the region. Models indicate the moderate instability
will move into eastern North Dakota...along with deep layer shear
around 40 knots. These parameters would favor supercell storms.
However...a strong 850mb low level jet will be focused near our
southern forecast area at 06z...then veer southeast into southern Minnesota by
12z. Thus...not sure if there will be enough dynamics to support
nocturnal severe storms. Neighborhood probability type products
show very low chances for severe storms past sunset. Although
scattered thunderstorms are likely...the stronger storms will be
more isolated.

Guidance is now quicker with the passage of the cold front/surface
trough on Friday...meaning that the afternoon/evening severe
threat is likely shifted east of the forecast area (into north central
minnesota).

Long term...(friday night through wednesday)
issued at 345 am CDT Thursday Jul 24 2014

Friday night-Saturday night...upper level low will propagate from
Saskatchewan into northern Minnesota. Showers and possibly some
thunder will be possible across the northern portions of the forecast area.

Sunday-Wednesday...the strong upper shortwave trough will rotate
southeastward into the Great Lakes on Sunday. Energy diving south
on the back-side of the upper low and cool air aloft could still
result in a bit of shower/storm activity. Cool highs in the upper
60s to low 70s are expected with 850 mb temperatures in the 7-10c range.

Otherwise...through the rest of the period...a return to an
amplified East Coast upper trough/western US ridge is
expected...with surface high pressure slowly working eastward across
the plains. A slow moderation in temperatures to near seasonable averages
will occur. Rain chances will be low...with limited moisture
return/instability...dependent upon any impulse that may dive
southeastward in the northwest flow towards the middle of next week.

&&

Aviation...(for the 12z tafs through 12z Friday morning)
issued at 643 am CDT Thursday Jul 24 2014

Stable airmass remains across the region and anticipate little to
no thunderstorm activity through much of the day. Chances increase
tonight...but coverage may not be widespread and did not mention
in the forecast. Ceilings will be VFR...with breezy southeast winds
developing.

&&

Fgf watches/warnings/advisories...
ND...none.
Minnesota...none.
&&

$$

Update...tg
short term...tg
long term...tg/makowski
aviation...tg

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