Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 161006

Area Forecast Discussion
National Weather Service Hastings NE
506 AM CDT Mon Apr 16 2018

.SHORT TERM...(Today and tonight)
Issued at 446 AM CDT Mon Apr 16 2018

To be certain, the vast majority of "action" in the latest 7-day
forecast can be found in the Long Term section below, as overall
these next 24 hours will be fairly "quiet" with guaranteed dry
conditions, milder (albeit still below normal) temperatures and
relatively light breezes. That being said, the short term is not
without some subtle challenges, namely: 1) The evolution of a
very pesky low stratus deck that has plagued roughly the northeast
half of the coverage area (CWA) since yesterday and continues to
do so...2) Any resultant effect this stratus could have on high
temps today, especially if it lingers longer than currently

Before getting into the forecast details, two side notes of sorts:
1) Sunday marked the second-consecutive day of record/near-record
cold, and at least at Grand Island/Hastings we can now officially
declare that this was THE COLDEST first half of April on
record...see separate climate section below and also an
infographic that will be posted on the web/social media within a
few hours for more details.

2) For those who might have missed it in this product over the
weekend, see AFDGID issued 457 AM Sunday for some "closing
comments" on the April 13-14 winter storm.

Turning to the current/recent weather scene as of 4 AM...
Clearly the biggest issue/challenge of the ongoing night/early
morning has been the evolution of the pesky low stratus deck
currently blanketing roughly the east-northeast half of the CWA.
As "feared" here 24 hours ago, this deck of clouds did in fact
survive well into the night despite the insistence of some (not
all) models/guidance to the contrary. In the big-picture of the
mid-upper levels, things have definitely quieted down over the
past 24-48 hours, as water vapor satellite and short term model
initialization depict the center of our long-departed low near the
southern tip of Lake Michigan, while we are increasingly-
influenced by a brief round of ridging moving in before the
Tuesday night system arrives. At the surface, the heart of an
elongated north-south ridge axis (local pressure around 1024
millibars) is centered through our CWA, providing much lighter
breezes than lately. That being said, several spots especially in
the east half of the CWA have still reported speeds of 10+ MPH
through most of the night so far, while west-southwest counties
are becoming more light/variable. Getting back to the
aforementioned "stratus problem", its evolution through daybreak
will obviously play a big factor in low temps this morning, as
clear areas (mainly west) will easily bottom out in at least the
upper teens, while cloudy areas (mainly east) will struggle to
drop below the mid 20s. Speaking of these cold lows, based on
climatology alone, there is a decent chance that most of the CWA
will probably not see another night this spring as cold as this

Now looking ahead forecast-wise through today/tonight...

Early this morning and Today:
Not to belabor the point, but if not for the stubborn low stratus
deck staring back at me all night on GOES-16 satellite, this would
likely be a pretty straightforward forecast. As of this writing,
it generally encompasses areas east of an Ord-Minden- Tipton KS
line, while to the west skies are essentially clear. One of the
few models that seem to be handling its evolution somewhat well
(in low-level RH fields) is the RAP13, so have generally tried to
follow its solution closely. This means that between now and
sunrise, this cloud mass should continue to gradually erode along
both its western and eastern edges, in other words becoming
"skinnier" with time but still remaining focused over especially
our eastern 1/3 to 1/2 into at least the first part of the
daytime. However, by mid-morning (perhaps 10AM-ish?) it should in
theory scatter/out dissipate to the point it is no longer much of
a factor through the remainder of the day. As a result, other than
some fairly thin high cirrus pushing in from the west mainly this
afternoon, the day as a whole is currently expected to average
mostly sunny in most areas. That being said, low stratus can be a
very fickle entity, and even if it does mostly or completely
disappear by mid-morning, would not be surprised to see at least a
scattered "fair weather" low cloud deck redevelop with daytime
heating this afternoon, especially within our northeast 1/2.
Backing up a bit, 24 hours ago was a bit concerned about a
corridor of at least patchy fog mainly in our western/southern CWA
this morning within the axis of lightest winds, but so far there
has been no real hint of this and short term RAP/HRRR visibility
progs are not very supportive of much fog formation in our CWA at
all. As a result, have formally pulled all patchy fog mention
except for western Dawson County which would seem more favored
than anywhere at this point. At the surface today, the ridge axis
currently over our area will gradually slide east toward the MO
River. As a result, breezes will gradually transition from
northerly, to very light/variable, before eventually becoming more
established from the east-southeast especially this afternoon. In
general, afternoon sustained speeds should only top out around 10
MPH east and 15 MPH/gusts around 20 MPH west. As for high temps,
am banking on sky cover averaging no worse than mostly sunny
(especially this afternoon), and have nudged up values roughly 2-3
degrees from previous forecast, aiming for a range from mid 40s
north to mid-upper 50s far south- southwest...certainly an
improvement but still a solid 10-15 degrees below normal.

This evening/tonight:
Not a lot to discuss really. In the mid-upper levels, our brief
shortwave ridging will start to depart as a large-scale trough
approaches from the southwestern CONUS. Locally, however, the
night is still very much dry, with only increasing, primarily high
level cirrus from the west as the night wears on, resulting in
generally partly cloudy skies. That being said, very late in the
night toward sunrise there could be a quick development of another
lower cloud deck, this time mainly in our southern zones. At the
surface, at least weak pressure falls will promote a steady-but-
relatively light east-southeast breeze through the night,
generally no more than 10-15 MPH with some slightly higher gusts
possible. The combo of these steady breezes and increasing cloud
cover all but guarantees a slightly milder night than the ongoing
one. Made very little change to previous low temps, aiming for
upper 20s north to low-mid 30s south.

.LONG TERM...(Tuesday daytime through Sunday)
Issued at 500 AM CDT Mon Apr 16 2018

A ridge of high pressure will be transitioning across the plains to
start the extended periods as a trough of low pressure crosses the
intermountain west. Expect the warmest day of the week
mostly sunny skies and high pressure aloft help temperatures climb
into the 60s across south central Nebraska...and into the lower 70
across our Kansas counties. This warm up will be short the aforementioned upper level system works its
way into the plains late Tuesday...and rapidly tracks across the
local area on Wednesday. As this system approaches the local area
Tuesday afternoon...expect a small amount of instability to build
ahead of its arrival...and with forcing from the upper level low and
modest low level moisture in place...expect the possibility for a
few thunderstorms during the evening hours. With only modest
instability and severe weather is expected at
this time.

Thereafter...temperatures should plummet as cooler air filters in
from the north...allowing for a switchover to snow primarily north
of interstate 80...with now 1-2 inches of snow possible primarily
across areas north of highway 92 Tuesday night. That said...this
will be a very progressive another upper level ridge is
anticipated to build back in across the local area by Wednesday
afternoon as yet another...more powerful...upper level low organizes
across the four corners region. Ahead of this next system...a windy
afternoon is expected on Wednesday...and while temperatures will not
be as warm as Tuesday...drier air filtering in combined with these
breezy/wind conditions...will result in at least elevated fire
weather concerns across north central Kansas Wednesday afternoon.

Behind this system...Thursday should be a fairly nice day across the
region as lighter winds under an upper level ridge take over across
the region. While temperatures will not be as warm as Tuesday...with
the lighter winds and mainly cloud free skies...Thursday should be a
fairly nice day ahead of the vigorous upper level low forecast to
lift out of the southwest and into the plains on Friday. With the
track of this next low now consistently tracking east near the OK/KS
state lines the past couple of mornings...confidence is increasing
that cooler air will once again filter in across the local area
along with generally unsettled conditions late Thursday night
through Sunday morning. As a result...while most areas will see
primarily rainfall...some areas...mainly north of interstate
80...will see the possibility for a few light snow showers mixed in
during the overnight through early morning hours late Thursday
through Sunday morning. At this time...significant snowfall
accumulations are not anticipated...but there is still plenty of
time for a change in the trajectory of this low pressure system as
it emerges into the plains late in the week.


.AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Tuesday)
Issued at 113 AM CDT Mon Apr 16 2018

General overview:
Confidence is very high in precip-free conditions and is
moderately high in VFR visbility throughout. That leaves ceiling
as the major question mark, especially during these first 3-6
hours as a stubborn MVFR stratus deck has remained in place (KGRI)
or moved back in from the east (KEAR). Wind-wise, this will be a
much "quieter" period than the past few days, with sustained
speeds throughout the period largely below 11kt, and direction
transitioning from light/variable to southeasterly-easterly with
time. Read on for more ceiling comments...

As was suspected here 24 hours ago, the MVFR stratus that had been
in place much of the past 24 hours at KGRI (and has since drifted
back west into KEAR) has been a struggle for several sets of
forecast models/guidance to handle. Based on satellite trends and
what currently appears to be the most reliable model solution,
this MVFR deck should gradually erode along its edges during these
first 3-6 hours. In theory, KEAR is most favored to return to VFR
first and have taken a "best stab" with 09Z, while KGRI could
easily hold on a few hours longer, and have gone with 12Z. Of
course, each of these times could easily be off somewhat given the
already very tricky nature of this cloud deck. Once the stratus
finally does abate, expect no worse than scattered lower clouds
during the day, and scattered high clouds Monday evening.


Issued at 446 AM CDT Mon Apr 16 2018

A few climate records notes regarding our incredibly cold
(overall) start to April at Grand Island and Hastings airports,
our two primary climate records sites...

Thanks in large part to the past few days, both of our
primary sites have set a new mark for coldest first half of
April on record (based on average temperature/average of
highs and lows).

-- Grand Island airport (top-3 coldest April 1-15 on record):
1) 36.0 degrees...2018
2) 37.0 degrees...1957
3) 37.8 degrees...1983

-- Hastings airport (top-3 coldest April 1-15 on record):
1) 36.5 degrees...2018
2) 37.4 degrees...1920
3) 37.5 degrees...1997

 temp for April 15th, and also the coldest high on record so late
 into the spring at Grand Island!
- Grand Island: New April 15th record of 31 degrees (previous was
  32 in 2000). This was the latest spring occurrence of a max temp
  of 31-or-colder on record. Oddly enough, the previous latest
  mark was just set the day before on April 14th.
- Hastings: New April 15th record of 31 degrees (previous was 32
  in 2000).

Coldest LOW temp for April 15th:
- Hastings: New April 15th record of 21 degrees...previous was 23
  in 2014




SHORT TERM...Pfannkuch
CLIMATE...Pfannkuch is the U.S. government's official web portal to all federal, state and local government web resources and services.