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Area forecast discussion 
National Weather Service Grand Forks ND
138 PM CDT sun Jul 5 2015

issued at 138 PM CDT sun Jul 5 2015

Quick update to pull the northwestern corner of the watch out. The
cold front has moved through...and although there is still a small
amount of instability behind the boundary think that cells going
up in that area will be sub severe and short lived. Kept Cass
County and Minnesota counties still ahead of the front...Polk County made
it complicated as Crookston is well in the cool air and Fosston is
still out ahead of the boundary. Kept the weird shaped counties
in just for ease and will pull them out in the next update.

Update issued at 1251 PM CDT sun Jul 5 2015

Storms moving into northeastern County Warning Area have started to lose their
punch as they have moved east. The cold front has moved through
gfk and Valley City...and out ahead of the front conditions have
been destabilizing nicely. The hrrr has some additional
thunderstorms developing along the cold front around 19-21z and
depending on how fast the boundary moves through this seems
reasonable. Will continue to keep fairly high probability of precipitation redeveloping
mostly over our south and east near the boundary for this
afternoon and evening.

Update issued at 1042 am CDT sun Jul 5 2015

Update for Severe Thunderstorm Watch. Storms moving into western
County Warning Area are starting to put out some wind...and storms will become
more surface based as they move east.

Update issued at 940 am CDT sun Jul 5 2015

Convection has fired mainly north of Highway 2 as the shortwave
trough approaches...with additional storms further south into
central ND along the surface boundary. Hrrr has a good handle on
convection this followed for the next few hours.
Precipitation will continue mainly in the north this morning with the
best lift...then shift south later today as the cold front pushes
south and surface based instability takes over. Included a severe
mention even this morning given a few elevated storms have pulsed
up enough to produce hail. Will make further adjustments as clouds
move into the area and could impact destabilization later today.

Update issued at 653 am CDT sun Jul 5 2015

Unfortunately still unsure how exactly this potential severe event
is going to unfold. Area of weak thunderstorms now across central
North Dakota continues to approach the region...and is about to
enter a more unstable atmosphere. There is the potential for at
least stronger storms across the northern forecast area this morning. This
system may provide enough cloud cover that convective development
this afternoon will be delayed...which would shift the northern
edge of the severe threat south (latest hrrr depicts development
along and south of a Bemidji to Jamestown line). Will need to see
what happens in the next few hours before adjusting the
forecast...the current forecast is in decent shape considering
most incoming guidance.


Short term...(today through monday)
issued at 355 am CDT sun Jul 5 2015

Initial area of thunderstorms associated with 850mb warm air
advection continue to slowly propagate eastward...and into a less
favorable environment for stronger/organized storms. Anticipate a
brief break for most areas and then severe thunderstorm potential
quickly increases by early afternoon. 00z models are in agreement
that a low level boundary that currently (08z) extends from near
dvl to bde will be in a similar location around 18z...with 80f to
90f temperatures and dewpoint values in the upper 60s south of
this feature...leading to moderate instability (mlcape 1500-2500
j/kg). The upper trough propagating eastward through Canada today
should be enough to gradually push this feature southward. 00z
guidance in agreement that near 30 knts deep layer shear will
overspread the warm sector. Judging from the past overnight
activity...severe storms seem likely considering similar
environment but will occur during peak heating. Hail up to 2-2.5
inches and damaging wind gusts would appear to be the main
threats. Individual storms will be moving relatively quickly...but
the low level boundary will be moving very slowly and training
storms appear possible...which is a concern considering these
storms will have higher precipitation rates (pwats near 1.75 inches).
Will also need to watch the track of the surface low tonight as an
upper wave rotates through the region...and how much additional
rainfall from this system might occur (current indications are
that the heavier rainfall from this secondary system will remain
south of the region).

Still uncertain how this event will unfold...especially with how the
convective complex entering the western Dakotas will unfold and
how this affects storm potential this afternoon. Hrrr indicates
this system will weaken...but cloud cover could delay storm
development. Other guidance indicates mesoscale convective vortex from this complex could
lead to earlier convective development. Hopefully will have more
details with the 7am update.

Monday...cold pool aloft could lead to isolated showers. It will be
cool and windy.

Long term...(monday night through saturday)
issued at 355 am CDT sun Jul 5 2015

Monday night-Tuesday night...high pressure will lead to dry and
cooler weather.

Wednesday-Saturday...northwest flow is entrenched over the region
at start of extended period as weak shortwave approaches early on
Wednesday. This will result in a return to southerly winds at the
surface...warmer and slightly more humid conditions... and
scattered showers and thunderstorms for Wednesday afternoon and
evening. Thursday should be dry but warmer still as overall flow
shifts from a more southerly direction. Longer range model
guidance indicates that upper level trough should remain in place
off the California coast from Thursday into Saturday with a more
convectively unstable southwesterly 500 mb flow arching into the
central and northern plains from Friday into Saturday. GFS and
European model (ecmwf) are a bit out of phase toward end of period but all
solutions depict a commensurate increase in moisture and risk for
strong thunderstorms.


Aviation...(for the 18z tafs through 18z Monday afternoon)
issued at 1251 PM CDT sun Jul 5 2015

Expect widespread MVFR conditions in thunderstorms across the
northern Red River basin...along and north of Highway 200...through the
early afternoon. Conditions there will be improving to VFR
after middle afternoon from dvl into gfk...and through late
afternoon gfk into vwu. Areas soputh of Highway 200 will see
scattered MVFR conds in tunderstorms developing through the middle
afternoon and extending into early evening from far-bwp line into
central Minnesota lakes country. Late evening and overnight will
Post frontal drying and return to VFR conds.


Fgf watches/warnings/advisories...


long term...wjb/tg

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