Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 282116
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
416 PM CDT SAT MAY 28 2016

.SHORT TERM...(This evening through Sunday night)
Issued at 416 PM CDT Sat May 28 2016

For the first time in DAYS, we are finally enjoying a much-needed,
albeit potentially brief break from severe weather/heavy rainfall
chances from tonight into at least the first part of Sunday.
Although cannot guarantee it stays completely/totally dry tonight
in all areas, once the late afternoon showers/weak storms fade
from eastern counties the vast majority of measurable rain
potential should be over with until Sunday. Speaking of Sunday,
although we have noted that the latest SPC Day 2 outlook kept the
official Marginal Risk area slightly to our south, model data
suggests that a northward expansion of this Marginal risk "may" (key
word may) be warranted in future updates, and this will need
monitored. That being said, the biggest question for Sunday
afternoon/night has more to do with how many storms could even
form in the first place, as several models suggest it could be
pretty sparse.

Taking a quick look at the current scene as of 330 PM, other than
being a bit breezier from the west-northwest (gusts commonly
20-25 MPH especially within the northeast 1/2 of the CWA),things
have turned out pretty close to expectations from the early-
morning forecast. In the mid-upper levels, water vapor satellite
and short term model data indicate a well-defined shortwave trough
departing northeast through the NE/IA/SD/MN border area. There
has been just enough forcing/modest instability with mixed-layer
CAPE to around 500 J/kg to spark isolated shower/weak thunderstorm
activity mainly within our far eastern/northeast CWA this
afternoon, but the vast majority of the area has remained dry.
Slightly upstream, another weak wave is sparking isolated
convection in the Neb Panhandle. At the surface, the
aforementioned west- northwest breezes locally are flowing in
behind a roughly 1007 millibar low centered over the northwest IA
area. High temps appear on track to range between 72-77 most
areas.

Now looking ahead forecast-wise over these next 36 hours or so:

This evening/tonight: As the aforementioned disturbance to our
northeast continues to depart, confidence is reasonably high that
at least the vast majority of the CWA stays dry. That being said,
cannot completely rule out at least a few weakening
showers/sprinkles drifting in from the west, mainly from the
remnants of the current western NE activity. As a result, will
carry a generic "slight chance of sprinkles" for parts of the area
tonight. For the record, cannot completely rule out a few
steadier measurable showers, but confidence is not high enough to
go any more than sprinkles for now. Otherwise, under mostly clear
to partly cloudy skies and in the presence of fairly light,
generally southerly winds, low temps are aimed into the low-mid
50s.

Sunday daytime-night: Although the forcing is not nearly as
strong/concentrated as had been with the previous system(s) the
past several days, the area resides in quasi-zonal (generally west
to east) flow aloft, with hints of one or more subtle, low-
amplitude waves working through the flow and sparking fairly
uncertain thunderstorm chances. In all reality, the morning is
probably dry most areas, but at least kept a sprinkle possibility
going. Then during the afternoon and evening, modest but less-
than-likely thunderstorm chances return to all areas, as daytime
heating with highs aimed into the low 80s sparks respectable
mixed-layer CAPE at least into the 1000-1500 J/kg range, but also
with fairly weak deep-layer shear. Nonetheless, a few strong if
not severe storms are probably not completely out of the question
as alluded to in the opening paragraph. That being said, the
coverage of any storms could be pretty sparse. Kept slight chances
going post-midnight, but again most areas should stay dry.

.LONG TERM...(Monday through Saturday)
Issued at 416 PM CDT Sat May 28 2016

The very basics of this 6-day period:
We face at least one more potential risk for strong/severe storms
and locally heavy rainfall centered on Monday afternoon into
Monday night and possibly lingering into Tuesday as well, but
beyond that, confidence remains high in a fairly prolonged and
much-needed stretch of dry weather especially Wednesday-Friday.
The very last day of the latest 7-day forecast (Saturday) brings
back some "iffy" thunderstorm chances to parts of the CWA, but
this is far from a "sure thing". Temperature-wise, near to
slightly below normal is the best way to describe it. Highs/lows
were changed no more than a few degrees from previous forecast,
with highs on most days somewhere in the 70s, and lows generally
in the 50s, but with some upper 40s not out of the question
especially in northern/western zones on nights such as Tuesday
night.

Focusing a bit more on the Monday (Memorial Day) severe weather
chances: At least on paper, the current SPC Day 3 Marginal Risk
seems warranted, but at this point uncertainty in the details is
still relatively high. Compared to Sunday, models are advertising
a more unstable afternoon airmass with ML-CAPE rising into
generally the 2000-3000 J/kg range, but again deep-layer shear is
weaker than during the past week at generally only around 25kt.
That being said, with increasing forcing provided by a shortwave
trough drifting east-southeast from the Northern Rockies, this
should in theory support increasing coverage of storms, especially
by early evening and into the overnight. On the flip-side, the
morning stands a better chance of staying dry over the majority of
the area. Hopefully the severe weather picture comes into better
focus over the next 36 hours, but typical large hail/damaging
winds look to be the main threats, along with locally heavy rain.
Have maintained 60 percent "likely" POPs for most areas Monday
evening/night.

Respectable rain/storm chances linger into Tuesday as a
seasonably-decent cold front passes through, but admittedly the
low rain chances for Tuesday night/Wednesday could be getting on
increasingly-shaky ground as flow aloft transitions northwesterly
in response to a building western CONUS ridge.

&&

.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Sunday afternoon)
Issued at 1253 PM CDT Sat May 28 2016

Confidence is fairly high in VFR ceiling/visibility through the
period. A rogue shower/weak thunderstorm cannot be ruled out
mainly this afternoon. More details follow...

Ceiling/visibility: About the only "catch" to VFR is right away
during these first 6 hours this afternoon, as it is possible that
a brief, high-end MVFR ceiling could materialize as stratocumulus
continues blossoming over the area with daytime heating. However,
this cloud deck is more likely to remain VFR. Later in the period,
expect only varying degree of mid-level VFR clouds.

Precipitation/thunderstorms: Have gone with a generic "vicinity
shower" (VCSH) group for this afternoon to account for hit-and-
miss activity drifting through. However, a brief, weak
thunderstorm also cannot be ruled out. Beyond late this
afternoon, cannot guarantee it stays dry, but chances are too low
for TAF inclusion.

Winds: The strongest winds of the period will occur right away
this afternoon, with sustained speeds 12+kt and gust potential
15-20kt. Thereafter, a generally light (less than 10kt) breeze
will prevail, mainly from a south or southwest component.

&&

.HYDROLOGY...
Issued at 416 PM CDT Sat May 28 2016

Although it is certainly possible that localized, minor flooding
might still persist in other areas due to heavy rain over the
past few days, at least officially, the only Flood Warning
currently in effect is for southeastern Thayer County along the
Rose Creek.

Given how saturated several of our counties have become of late
(especially southeastern ones such as Fillmore, Thayer,
Mitchell)...this roughly 24-36 "break" in steady rain chances
could not have come at a better time. Even so, if some heavy
downpours develop again during the Sunday afternoon-Monday night
time frame, renewed flooding issues could easily develop and this
will need monitored closely.

&&

.GID Watches/Warnings/Advisories...
NE...None.
KS...None.
&&

$$

SHORT TERM...Pfannkuch
LONG TERM...Pfannkuch
AVIATION...Pfannkuch
HYDROLOGY...Pfannkuch



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