Area Forecast Discussion
Issued by NWS Hastings, NE

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630
FXUS63 KGID 241523
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
1023 AM CDT Fri Mar 24 2017

.UPDATE...
Issued at 1023 AM CDT Fri Mar 24 2017

The HWO was updated at 850 AM with the 13Z convective outlook to
introduce a MRGL risk for a svr tstm or two well SE of HSI.

Sat imagery shows the dry slot has overtaken most of the fcst area
and there is large-scale descent below 500 mb. The narrow band of
-RA from LXN-OLU is near the leading edge of the dty slot and is
being driven by fgen. While currently inching N...guidance from
the 14Z HRRR suggests it could become stationary this afternoon.
This is part of a larger band that extends from Ern CO northeast
into the Neb Sandhills. As the upr low drifts E...this band could
overtake much of S-cntrl Neb this afternoon along and N of I-80.

Where sunshine occurs over N-cntrl KS...and possible up into the
HJH area...destabilization under the cold pool aloft will probably
result in a few shwrs/tstms with daytime heating. There could be
some small hail (possibly up to 1") with these storms.

These will be lop-top storms with the frzg lvl around 7K ft. So
we could be issuing warnings if we see a 50 dBZ core get above 19K
ft. Effective deep layer shear will be dcrsg and probably below 30
kts per 09Z SREF...but 0-3 km SRH will be around 150 m2/s2. A
mini-supercell or two can`t be ruled out. If we see any rotation
with at 50 dBZ core above 19K...the prob for hail will go up and
we will be warning with better confidence.

Also...thunder was removed from the fcst for the rest of the day N
and W of the Tri-Cities per the 12Z NAM stability indices.

&&

.SHORT TERM...(Today and tonight)
Issued at 345 AM CDT Fri Mar 24 2017

An upper low pressure system in southeast Colorado will track
across Oklahoma through tonight, a little farther south than
models indicated 24 hours ago. Scattered showers ahead of the
system have continued through the pre dawn hours across much of
Nebraska with the main frontogenetic precipitation beginning to
organize across western Nebraska.

The cold frontal boundary will gradually advance southeast today,
reaching our southern zones by evening. Low cloud cover, rain
showers and cooler air behind the boundary will bring little
diurnal temperature rise across our western zones where afternoon
highs should average in the 40s, whereas farther south the dry
slot nosing into our southern zones will allow for a period of
insolation and temps should reach the 70s ahead of the front.

For precipitation today, high resolution models suggest a
potential lull or hit or miss activity for much of the day, with
rain showers and perhaps a thunderstorm occurring along our
western zones in the mid level frontogenesis. Also there is a few
hour window of opportunity for thunderstorms to develop across our
southeast zones in proximity to the cold front and if storms can
go in this area, cannot rule out the potential for a strong storm.

The precipitation begins to wind down from west to east heading
into tonight as the upper low system departs. The NAM remains the
most aggressive with the cold air with perhaps a rain/snow mix for
Dawson county before ending, but there is just not support from
other models with the airmass cold enough for snow this far east
and have kept precipitation type as liquid. Cooler and drier air
behind the system will result in a chillier night with lows
averaging in the 30s.


.LONG TERM...(Saturday through Thursday)
Issued at 345 AM CDT Fri Mar 24 2017

Primary forecast concern through the long term lies with multiple
chances for precipitation.

At the start of the period Saturday morning, models are in pretty
good agreement showing the main upper level low pressure system
located in the KS/MO/OK/AR border area. Moisture wrapping around
the backside of the low will keep some small chances for showers
around eastern portions of the CWA through the first half of the
day. As the low moves further east into Missouri, precip is
forecast to end for the afternoon, but lingering light precip
might not be too far outside the CWA. At the surface, a high
pressure ridge axis will start working its way in from the west
during the day, with north- northeasterly winds should diminish in
speed. Skies across the easterly half of the CWA look to remain
mostly cloudy, the further west you go the more sun you`ll see.
High temperatures are forecast to range from near 50 in the east
to near 60 in the west.

Saturday night into at least part of the day on Sunday, the
forecast is dry, with shortwave ridging sliding through the
Plains. Already Sunday morning, the next upper level disturbance
is knocking on the door, at 12Z Sun located over eastern CO.
Models in good agreement taking the path of the system through KS,
keeping the brunt of the lift/precip chances across the southern
half of the CWA. Precip will slide off to the east Sunday night.
Highs on Sunday remain in the 50s/low 60s.

Another "brief" lull in the forecast comes Monday/Monday night,
as once again upper level shortwave ridging between systems passes
through the Plains. Expecting to see a bit more in the way of
sun, highs are a few degrees warmer in the lower/mid 60s.

Unsettled weather returns for the remainder of the forecast
period, through Thursday night. At 12Z Tuesday, models are showing
the next upper level low moving through the Four Corners region.
Lift is on the increase during the day as the system slides east,
ending the day roughly over northern NM. At this point, the better
precip chances looking to be over the western half of the CWA.
Over Wed/Thurs, models not showing much change in its eastward
trek, crossing it mainly through OK, perhaps taking a slight
northeast turn into southern Missouri late in the day Thursday.
Plenty of uncertainty with just how much moisture spreads far
enough north to affect the CWA, with the ECMWF more generous with
its QPF than the GFS. Not much instability shown by models, so no
mention of thunder in the forecast. We`ll see how things trend in
the coming days. Highs Tue-Thurs mainly in the 50s to lower 60s.

&&

.AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Saturday)
Issued at 601 AM CDT Fri Mar 24 2017

It`s a complicated TAF period with regards to timing of
precipitation and varying low cloud cover. Rain showers will be
hit or miss today and into tonight and an isolated thunderstorm is
possible mainly during the afternoon and early evening. Low cloud
cover was settling into the terminals behind a cold frontal
boundary. Cloud cigs generally range from LIFR to IFR however some
of the short term models suggest an MVFR and possibly a cig near
VFR. Current tafs are pretty pessimistic with the expected low
clouds. Northerly winds will be on the increase today with wind
gusts around 30kts. Lingering rain shower activity will gradually
decrease from west to east overnight or early Saturday morning.

&&

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

$$

UPDATE...Kelley
SHORT TERM...Fay
LONG TERM...Pfannkuch
AVIATION...Fay



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