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Area forecast discussion 
National Weather Service Hastings NE
624 PM CDT Tuesday Oct 6 2015

Short term...(this evening through wednesday)
issued at 358 PM CDT Tuesday Oct 6 2015

.Fcst uncertainty above average through tomorrow due to stubborn
stratus but improvement is possible tomorrow with warming temperatures...

Aloft: as the case has been since early sept...but the main band of
westerlies was over southern Canada. Its amplitude was low. The flow over
the Continental U.S. Was relatively weak with a cut-off low over the desert SW.
The ridge ahead of this low was currently overhead. The dry slot/pv
anomaly was circulating around the east semicircle of this low. This pv
anomaly will move in tonight...knocking down the ridge. It will then
become elongated west-east across Nebraska tomorrow.

Surface: a cold front extended from low pressure over Hudson Bay SW
across Lake Superior to Minnesota across the sandhills and then northwest into the
northern rockies. This front may sag down to I-80 for a time tonight but
will stall. This front will lift back north as a warm front tomorrow as
low pressure tracks along the US-can border.

Now: stubborn stratus is a major forecast headache...especially because
of its sharp edge. This stratus is trapped below an inversion per
the 12z lbf sounding. It has suppressed temperatures north of Highway 6 today.
Expect very little change through sunset other than the cumulus dissipating
S of Highway 6.

Tonight: this differential in clouds (clear vs cloudy) makes the
temperature forecast a nightmare. Multi-model cross sections are in good
agreement on moisture persisting around 800 mb...but they do not
have the detail on where it will not be. Cloud variability will
judge how low temperatures go. We are probably not cool enough where skies
end up M/clear.

Forecast adjustments in clouds/temperatures will be necessary this evening as
trends become clear.

Tomorrow: probably a continuation of tonight at least through midday.
It will be dictated by cloudy vs clear. Although cross sections
suggest the stratus should clear in the afternoon. This seems
reasonable as it is on the SW fringe of a pool of cooler air and
this pool will shift east of the region. So expect decreasing clouds
where the day starts cloudy with temperatures turning warmer...roughly 6-8f
above normal.

The pv anomaly will have minimal moisture to work with and forecast
soundings maintain the cinh seen on the 12z ddc observed sounding
this am.

Long term...(wednesday night through tuesday)
issued at 358 PM CDT Tuesday Oct 6 2015

Not a lot of noticeable change to this 6-day period has been made
versus the previous few forecast issuances over the last 24
hours. Very generally...this means that in the precipitation
department the only thing going on is a pesky and still somewhat-
uncertain chance for showers/a few non-severe thunderstorms during
the Wednesday night-Thursday time frame. Beyond that...aside from
a just-added slight chance of sprinkles added to Kansas zones Thursday
evening...the entire County Warning Area has a dry forecast from Thursday night
all the way through at least Tuesday.

Temperature-wise: have made only a few fairly minor (3 degrees or
less) tweaks to both highs and lows...but the big story continues
to be above-normal warmth for early-to-mid October with most days
featuring highs somewhere between the middle 70s and low 80s...and
more in the way of widespread low-middle 80s (and even upper 80s in
Kansas zones) Sunday. Although the forecast highs for Sunday are
obviously still subject to plenty of fine-tuning being 5 days won't take much more of an upward nudge to possibly
threaten the Oct. 11th record high at Hastings (89 degrees in 1975
and 1940).The one day that continues to be a cooler exception (but
still right near-normal) is Friday with highs aimed into the upper
60s-low 70s range. As for overnight follows suit that
most nights currently feature above- average lows in the upper
40s- middle 50s range...with the only real cooler exception being
Thursday night with more in the way of low- middle 40s mainly in Nebraska
zones. At least one set of guidance continues to suggest that some
upper 30s are not out of the question in far northern counties
such as valley...but even if this were to occur am not
anticipating values cold enough for frost formation at this time.
As stated here yesterday...there is essentially zero apparent risk
of any portion of the County Warning Area experiencing its first fall freeze
through at least Oct. 13...thus almost assuring a later-than-
average first freeze for even southeastern portions of the County Warning Area.
(See web story posted at the top of our home Page for more

Before diving into day-to-day details...also wanted to comment on
the potential for at least modestly-increasing fire danger on a
few of these upcoming warm days. At least for now...the official
forecast features no afternoons with an overlap of relative
humidity at/below 20 percent and sustained winds at/above 20 miles per hour
(the thresholds needed to trigger Fire Weather Watch/warning
issuance). However...this wouldn/T be the first time that
forecasted fire parameters worsened as a day draws
this will bear watching given that vegetative fuels are starting
to dry out a bit more in many areas despite the lack of a
widespread frost/freeze.

Now finishing up with the usual dose of day-to-day details and
uncertainties in 12-48 hour blocks...with the biggest focus on
Wednesday night-thursday:

Wednesday/evening-night: for being such a low risk of measurable
rain as a whole...this is a pesky period. Officially...have gone
with only a slight 20 percent chance of showers/isolated weak
storms in all areas at some point during the night...but some
models (such as the nam12) essentially keep all areas Bone-
dry...while others (such as the gfs) paint a bit more widespread
rain potential within the area. Turning to the higher-res
solution of simulated reflectivity from the 12z 4km WRF-nmm...the
truth may very well be somewhere in the middle...meaning that a
few places catch a spotty shower/storm while most Don/T. For now
will just continue to blanket the slight chance all areas given
the inherent uncertainty. No matter what...the more favorable rain
chances during the night should focus generally 100-200 miles
northeast of the County Warning closer proximity to a shortwave
disturbance tracking east-southeast across the Dakotas toward the
Great Lakes. At the surface...initially southerly breezes in the
evening will turn more westerly as the night wears on just ahead
of an approaching surface cold front that should just be entering
the northwest edges of the County Warning Area around sunrise.

Thursday daytime-night: continuing the same theme from Wednesday
night...another pesky 24 hours of precipitation forecasting for only
officially being 20-30 percent chances at most. In the middle-upper
levels...the trailing southwestern portion of the aforementioned
Great Lakes region trough will pass over the Central Plains in
northwest flow aloft...with some modest amplifying/strengthening
occurring as it does so. Despite the halfway-decent synoptic
forcing...model variances continue regarding rainfall
chances...with the latest nam12 continuing to be eerily
dry...while other solutions such as from the 12z European model (ecmwf) suggest
that especially the afternoon hours could feature a fair amount of
scattered shower/at least sprinkle activity just ahead of the
passing middle level trough axis. Obviously Thursday will start
coming into better focus over the next 24 hours as the higher-res
shorter-term models come into play...but for now went with only a
slight chance of non-measurable sprinkles in northern zones...up
to only a 30 percent chance of showers in southern zones. Am not
completely comfortable without at least having a slight
chance/isolated mention of a few non-severe thunderstorms during
the day...but the previous night shift just pulled out this
thunder mention...and instead of "flip-flopping" this aspect of
the forecast will just keep it generic rain showers for now and
let the next few shifts take a closer look to see if maybe an
isolated thunder mention may need re-introduced. As if the day is
not tricky enough...a few models (especially the ecmwf) are now
suggesting that at least a spotty shower potential could linger into
Thursday evening as well...especially in southern zones. Although
this seems possible given that the middle level trough axis will not
have yet cleared the not sold on inserting a legit
measurable pop into the evening forecast just yet. As a
compromise...have introduced a "slight chance of sprinkles" to the
far southern County Warning Area during the evening...while maintaining a dry
Post-midnight all areas.

Friday daytime-night: despite the passage of at least one
additional...weaker disturbance in northwest flow aloft behind the
stronger one that has already moved through by this time...models
continue to be pretty insistent on a dry 24 hours here. Would not
be surprised to see clouds be a bit more prevalent than currently
advertised however. At the surface...high pressure prevails during
the day resulting in fairly light/somewhat variable breezes before
southerly flow picks back up at night. No matter...this still
looks like the overall-coolest day of the next week for most of
the County Warning Area.

Saturday daytime-Sunday night: 12z runs of the European model (ecmwf)/GFS remain in
fairly impressive agreement for this entire 48-hour weekend
period...with most of it dominated by broad low amplitude
ridging...resulting in above normal warmth (especially sunday) and
almost none chance of rain. Saturday is trending toward being
rather breezy out of the south...and there is decent agreement
that a modest cold front will pass through Sunday night in
response to the next quick-moving disturbance passing by just to
the north.

Monday daytime-Tuesday daytime: these last 36 hours of the
official forecast continue to carry a reasonably high confidence
of staying dry as broad ridging aloft continues to be the dominant
influence. Temperatures are a bit tricky for Monday in the wake of the
Sunday night front...but for now still have highs well up into the
70s to low 8os on both days.


Aviation...(for the 00z kgri/kear tafs through 00z Wednesday evening)
issued at 619 PM CDT Tuesday Oct 6 2015

Stratus continues across the terminals this evening and it appears
it will remain through the night. There could be a few
breaks...but the clouds should fill back in during the overnight


Gid watches/warnings/advisories...


Short term...halblaub
long term...pfannkuch

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