Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 290957
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
457 AM CDT Mon May 29 2017

.SHORT TERM...(Today and tonight)
Issued at 357 AM CDT Mon May 29 2017

Another nice day is expected across the region with near
seasonable temperatures and occasionally gusty northwestelry
winds. While the radar so far this morning is quiet...models are
picking up on a weak disturbance across the high plains which may
bring a few light showers or sprinkles to north central Kansas
later this morning and possibly into the afternoon hours. In
addition...with very deep mixing forecast...on the order of 700
mb...could once again see some high based CU develop later in the
day...with a sprinkle at any given location not completely out of
the question. While confidence of this was low enough to emit from
the forecast...did increase cloud cover through the afternoon
hours.

With the anticipated deep mixing...also increased winds across the
region this afternoon...with occasional gusts of 30 to 35 mph not
out of the question.

For tonight...expect dry and seasonable conditions to
continue...although a weak disturbance towards morning could
produce a few light showers towards daybreak...but think that the
better chance for this lies just beyond the short term portion of
the forecast.

.LONG TERM...(Tuesday daytime through Sunday)
Issued at 457 AM CDT Mon May 29 2017

General overview of this 6-day period (including storm chances):
First night closely examining these long term periods for this
particular forecaster, so not a great handle on recent model
history. However, in perusing the latest data and also reviewing
our recent discussions, there have been little in the way of
noticeable forecast changes, and generally agree with previous
forecasters that the majority of this time frame appears rather
"quiet" by late-May/early June standards. That being said, with
temps climbing/averaging slightly above-normal and surface
dewpoints (indicative of increasing low-level moisture/humidity)
rising into the 50s to even some 60s mainly Wednesday-Saturday, we
need to be cautious about overly-downplaying chances for at least
isolated strong-to-severe storms on various days/nights. While
upper level forcing/dynamics are admittedly rather weak/nebulous
much of this time, the increasing amounts of CAPE/instability may
tend to make the most of even weaker forcing at times. Not
surprisingly, SPC has continued and/or introduced Marginal Risks
of severe storms to mainly southern portions of our CWA for both
Day 2 (Tuesday) and Day 3 (Wednesday), and would not be surprised
if the Marginal for Wednesday afternoon-night gets expanded
northward as it gets closer in time, as this also still appears to
be our overall-best chance of more widespread rain/thunderstorm
activity in general. In addition, although the details get murkier
as usual beyond the first few days, would also not be surprised
if another Marginal Risk type setup eventually materializes around
the Friday-Saturday time frame. Again though, all this being
said, confidence remains high that these 6 days as a whole will
prevail dry the vast majority of the time.

Temperature-wise:
After averaging being below normal on most days over the past few
weeks, confidence is pretty high that we are entering a solidly
(albeit not dramatically) above normal regime (for reference,
"normal" highs are generally upper 70s/lows mid 50s). If anything,
highs on most days were nudged up 1-2 degrees from the previous
forecast package. More specifically, highs are expected to climb
from mainly the upper 70s/low 80s on Tuesday-Wednesday, more so
into the mid-80s (upper 80s southwest) Thursday-Friday before
possibly easing back a little into the mid-70s to low-80s range
for next weekend, although there are hints that our going values
for next weekend could be aimed a bit too cool. Correspondingly,
after our recent prolonged stretch of most nights falling well
into the 50s or even 40s for lows, we are now looking at a decent
stretch of nights holding up more so in the low-60s especially
Wednesday night-Friday night. Again, far from record-breaking, but
nonetheless more of a "summery" feel than lately.

With the basic precip/thunderstorm and temperature expectations
outlined above, will end as usual with some attempted day-to-day
details, although will focus the majority of this effort on the
closer-range Tuesday-Thursday time frame...

Tuesday daytime:
We remain under our current/ongoing northwest-flow-aloft regime,
as the Central Plains is brushed by a series of small-scale
disturbances rotating around the backside of a larger-scale trough
centered over the Upper Great Lakes/southeast Canada region. At
the surface, a rather weak cold front will settle southward
through our coverage area (CWA) over the course of the day,
reaching far southern zones in KS by mid-late afternoon. While the
vast majority of the CWA should see a mostly sunny day with
northerly breezes only averaging 5-15 MPH, various models continue
suggesting that mainly our extreme southern KS counties
(Rooks/Osborne/Mitchell) could see some strong to perhaps
marginally severe storms fire up with peak heating along this
boundary, before quickly departing southward out of our domain by
00z/7PM. As is often the case, the NAM shows considerably higher
mixed-layer CAPE to work with (perhaps 1500+ J/kg) compared to the
GFS (closer to 500 J/kg), but even taking the lower-end of this
range, this may be enough for a quick bout of marginally-severe
storms with a hail/wind threat in the presence of around 40kt of
deep layer shear. Whether or not any strong-severe storms do
affect our KS zones during the afternoon, we are also carrying
some low precip chances (PoPs) in this same area during the
morning to account for some possible early-day shower/weak storm
activity.

Tuesday evening-mid-afternoon Wednesday:
Confidence is pretty high that this 18+ hour period should largely
remain dry (and the official forecast reflects this), although
there are subtle hints in the latest NAM that perhaps Wednesday
morning could already feature some spotty shower/weak thunder
activity. Overall though, Tuesday night looks to be the last
coolish night of the week with lows ranging from mid-40s far north
to mid-50s far south.

Late Wednesday afternoon-early Thursday morning:
As mentioned in the overview section, this 12-15 hour period
continues to carry our overall-highest rain/thunderstorm chances
of the entire week for the CWA as a whole, although PoPs have been
kept below "likely" percentages for now until details become a bit
clearer. Very generally speaking, the mid-upper air pattern
flattens out/becomes more zonal, allowing a series of subtle/low
amplitude disturbances to head eastward into the Plains. At the
surface, a fairly classic warm-air advection/northward-lifting
warm front pattern will commence, with Wednesday featuring
somewhat breezy southeast winds turning more true-southerly
Wednesday night into Thursday. Despite the relatively weak upper
forcing, relatively cool mid level temps and respectable
instability generally as high as 1000-1500 J/kg should allow a
halfway decent coverage of thunderstorms to commence, perhaps
starting late Wednesday afternoon in southwest counties but then
spreading north/east as the evening/night wears on. While not
expecting a high-end severe event, this looks like the kind of
environment that could perhaps foster a few slow-moving severe
supercell storms early on...morphing into more of a marginally-
severe cluster mode overnight with locally heavy rain. As earlier
stated, would not be surprised to see the current Day 3 Marginal
Risk area expanded as this setup gets closer.

Thursday daytime-Friday morning:
At least for now, this remains another dry interlude with warmer
temps as the Wednesday night convection moves off to the
north/east with the passing warm front and forcing remains weak.
that being said, with enough heating would not be surprised to see
very isolated convection develop with heating.

Friday afternoon-Sunday daytime:
While various, off-and-on chances for showers/storms return to the
forecast, the details are extremely murky as the mid-upper air
pattern remains fairly weak by early-June standards. About the
only things that look somewhat promising to have confidence in
are: 1) There are reasonable signals in both the ECMWF/GFS of a
cold front passing through Saturday, with the GFS showing somewhat
decent thunderstorm potential although the ECMWF/Canadian are
drier. For now, PoPs for Saturday are only 20-40 percent. 2)
Whether or not it storms Saturday into Saturday night, Sunday
would tend to favor largely dry and perhaps slightly cooler
conditions per both the ECMWF/GFS in the wake of the
aforementioned front, although even this is difficult to
guarantee at this Day 7 time range in such a pattern.

&&

.AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Monday)
Issued at 1230 AM CDT Mon May 29 2017

VFR conditions are anticipated through the period. Expect some
passing high clouds...with a few mid level CU likely forming
during the afternoon hours again tomorrow as good mixing is
realized across the region. In addition...with the good
mixing...expect some gusty afternoon winds.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&

$$

SHORT TERM...Rossi
LONG TERM...Pfannkuch
AVIATION...Rossi



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