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Area forecast discussion 
National Weather Service Hastings NE
1222 PM CDT Tuesday Jun 2 2015

Short term...(today and tonight)
issued at 413 am CDT Tuesday Jun 2 2015

Convection which developed along the High Plains Monday evening
rolled eastward and reached our western counties around 06z.
Unimpressed with latest runs of models which are not handling the
pre dawn storms well at all and model runs 24 hours ago had a
handle a better handle on the potential for this activity.
Although convection is not showing immediate signs of winding
down...instability and moisture decrease to the east and this
round of convection should gradually taper off with time.

Aloft...the pattern featured an upper low pressure system moving
into the Pacific northwest with ridging acr0ss the plains
breaking down. In the low levels...a broad low pressure trough was
located in The Rockies and models are consistent with the surface
deepening in the western Dakotas initially with a surface trough
extending south and west through western Nebraska and eastern Colorado.
Then later in the evening the low refocuses in eastern Colorado. In a
tight pressure gradient with the surface low to the
west...south/southeast winds will be on the increase with
breezy/windy conditions expected. Model forecast soundings
indicate mixing around 850 mb with winds at the top of the layer
around 30kts and have ramped up wind speeds for today. Moisture
will continue to be drawn north with dps reaching the low/middle 60s.
Warmer temperatures above normal...in the 80s are also forecast and
instability is prognosticated to increase to around 3000 j/kg. Another
round of storms is forecast to initiate in the vicinity of the
boundaries to our north and west with storms reaching our County Warning Area
later this evening and tonight. The better chances for storms favors
our northern zones and conditions will be favorable for severe
weather in presence of good instability and shear.

Long term...(wednesday through monday)
issued at 413 am CDT Tuesday Jun 2 2015

Continual chances for thunderstorms will be primary concern in the
long term. Starting out with the big picture Wednesday morning...it
looks like there will be a cut off low over the Tennessee
Valley...weak ridging over the central U.S. And a broad low
amplitude trough along the West Coast. At the surface the primary
surface low is expected to be near the Kansas/Colorado border with a warm
front extending northeast across our County Warning Area.

Several models indicate that precipitation could either linger
across much of the County Warning Area during the day Wednesday...or fire along the
warm front during the late afternoon. Cannot discount either of
these so will need to keep 30-40 probability of precipitation going during the daytime. The
more likely scenario however seems to fit more with the latest ec
solution which has convection firing over the High Plains as a middle
level wave moves through and then an mesoscale convective system working through the County Warning Area
overnight as the low level jet Cranks up. Prognosticated instability and
deep layer shear values impressive enough to justify Storm Prediction Center slight risk
over most of our County Warning Area. Concerns include any daytime precipitation/
cloud cover which could damper instability. Also have middle level
capping which may lower the chances in the far south. Final concern
is while it looks fairly certain that a low level jet will
develop...just where the best speed convergence occurs is somewhat
in question. The ec shows it more towards the NE/Kansas state line while
the GFS is a bit further north. For now will keep the highest probability of precipitation
for the week going for the Wednesday night time frame.

Precipitation may linger again during the day on Thursday as stationary
front remains draped across the area and difficult to time
additional middle level waves coming across. May end up with another
mesoscale convective system coming through the County Warning Area overnight. GFS has better low level jet
focus a little ways east of our County Warning Area but other models not necessarily
showing this. Should also mention that by Thursday night the flow
changes just a bit as the West Coast low digs south which should
amplify the ridge over US a little. But I dont expect the ridge and
middle level warming to build in strong enough to shunt convection
further north. Thus will go a little higher with probability of precipitation in the east due
to the possibility of the low level jet focus along with the ridge
keeping the possible mesoscale convective system track just a bit more to the northeast.

For the rest of the extended will need to keep at least some kind of
probability of precipitation going most of the time. Doubt it will rain every days...but
tough to determine just when middle level waves will move across the
plains. The problem is that while the West Coast low remains
anchored there into the weekend and the ridge stays over the Central
Plains...it cannot build/amplify due to the northern jet staying far
enough south to bring middle level waves through the northern plains.

&&

Aviation...(for the 18z kgri/kear tafs through 18z Wednesday afternoon)
issued at 1220 PM CDT Tuesday Jun 2 2015

Low clouds have been persistent this morning and expect them to
continue into the afternoon. They have the potential to lift some
and eventually there could be some breaks toward evening...but
will leave them in for now. Thunderstorms are possible during the
overnight hours.

&&

Gid watches/warnings/advisories...
NE...none.
Kansas...none.
&&

$$

Short term...Fay
long term...ewald
aviation...jcb

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