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Area forecast discussion 
National Weather Service Hastings NE
1252 PM CDT Tuesday Sep 2 2014

Update...
issued at 1252 PM CDT Tuesday Sep 2 2014

Our hourly forecast dewpoints have been running too high and based on
lbf/oax soundings and current ob trends...this is not likely to
improve. So current dewpoints were blended with consensus of high-res
short-term model guidance the rest of the afternoon.

Update issued at 1021 am CDT Tuesday Sep 2 2014

Forecast is in good shape. Still doing some analysis/diagnosis and
getting spun up after several days off.

GOES-east will be put into rapid scan Mode at 1614z.

&&

Short term...(today and tonight)
issued at 405 am CDT Tuesday Sep 2 2014

Broad upper level troughing resulting from low pressure over far
northern portions of Canada continues to affect much of the northern
Continental U.S....with an area of elongated high pressure spread across the
southern Continental U.S.. satellite imagery showing a disturbance in the main
flow continuing to slide east across the Central Plains early this
morning...and along with the entrance region of an upper level jet
streak brought some shower/thunderstorm activity this evening but
has since tapered of to perhaps a few sprinkles across southern
portions of the County Warning Area. At the surface...the main frontal boundary
extends from up near the Hudson Bay area S/SW through the Great
Lakes and toward the panhandles of TX/OK. North of the
front...high pressure continues to build into the area from the
west...centered over western portions of Nebraska. Skies have been
gradually clearing as the disturbance slides east...and surface high
pressure has resulted in light/variable winds across the
County Warning Area...with temperatures having fallen into the Lower/Middle 50s for most
locations as of 3 am...NC Kansas still in the lower 60s.

Looking at the forecast for the daytime hours today...it remains
dry with models in good agreement showing little overall change
in the upper level pattern...remaining zonal with no notable
disturbances expected to slide through. High pressure will
continue to be the primary feature at the surface...keeping winds
on the lighter side through the day. The direction is expected to
transition from light/variable to more southerly with time...as
the the center of the high sets up to the east/southeast of the County Warning Area and a
trough of low pressure develops over the High Plains. Start to see
warmer air aloft advecting into the area through the day...with
highs expected to climb into the Lower/Middle 80s this afternoon.

No significant changes were made to the forecast as we get into
this evening and overnight...with there still the potential for
some precipitation across mainly the southeastern third of the County Warning Area. Models
continue to show a weak middle level disturbance moving through the
area...and together with increased lift thanks to warm
air/moisture advection associated with a stronger low level jet...show
precipitation sliding north/NE with time tonight. Made only minor adjustments
to the area...but did hold of probability of precipitation until after 03z. Enough
instability/shear present that a strong thunderstorm cant be
completely ruled out.

Long term...(wednesday through monday)
issued at 405 am CDT Tuesday Sep 2 2014

The biggest issue in the long term will be determining chances of
precipitation and thunder. Progressive west to southwest flow will
continue to not give US very long stretches of dry
weather...with the dry stretches being more typical of what to
expect in September.

We start off the the long term with a rather warm note. Numerical
models are in pretty good agreement that this will be a moist and
breezy day...and dry. Strong warm air advection and cap should
ensure this. The strong warm air advection continues into
Wednesday night ahead of an approaching cold front from the
northwest. I increased overnight lows...keeping middle 70s in the
south. I would have been comfortable bumping up the central and
southern County Warning Area by a degree from what I have in there.

Any precipitation in association with the front moving through
should be Post-frontal and elevated. This should generally hold
off until Thursday night. As the front continues to move
south...the elevated convection north of the front will follow and
eventually instability will substantially decrease to take out
thunder completely by Saturday. Saturday night should be dry for
the most part...under control of the surface high...but this high
quickly moves east and allows the front to begin returning as a
warm front. As a result...more elevated convection should fire in
our southwest Sunday...and spread northeast as the warm front
advances. There could be enough instability and shear by early
next work week for some severe weather...but it is too early to
tell to make much of a determining statement...at least not enough
to mention in the severe weather potential statement for now.

I liked the NAM for highs Wednesday as this is the last day
completely in the warm sector and went with consraw for lows
Wednesday night as this is the last night in the warm sector.
These models tend to do best in these situations. Went more
toward bcconsraw for highs on Thursday...and allblend for Thursday
night.

&&

Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1252 PM CDT Tuesday Sep 2 2014

This afternoon: VFR sky clear. Winds will eventually organize from the
SW under 10 kts. Confidence: high

Tonight: VFR sky clear decays to MVFR fog/IFR stratus around 10z. The
evidence for this is the MVFR stratus that has been lifting north
through the iml area this morning. The dewpoint at iml has increased
from 49f at 12z to 59f at 17z. So moisture is streaming north. Low level wind shear
will develop and this will keep the Richardson number very low...
indicating a mixed lower atmosphere which favors stratus. The GFS
lamp forecast guidance support it. Winds shift to southeast under 10 kts.
Confidence: medium due to uncertainty on onset of IFR stratus and
ceiling heights.

Wednesday morning: IFR stratus gradually lifts to MVFR and should begin
breaking up by 16z. Winds become S and gust up to 18 kts.
Confidence: medium due to uncertaint on ceiling heights and timing
of break-up.

&&

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

$$

Update...halblaub
short term...ado
long term...heinlein
aviation...halblaub

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