Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 151113
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
613 AM CDT Sun Apr 15 2018

.SHORT TERM...(Today and tonight)
Issued at 457 AM CDT Sun Apr 15 2018

Although the weather over these next 24 hours is clearly lower-
impact than the previous 24 hours, it nonetheless features several
subtle challenges, including: 1) Highly variable sky cover across
our coverage area (CWA) today, and the resultant impact on
temps...2) Highly variable snow cover, which could also make for
tricky temps today, especially where it is sunnier...3) The
possibility of pesky light flurries lingering past sunrise and
"ruining" what had been a completely precip-free daytime
forecast...4) The possibility of at least patchy fog tonight
mainly in our western/southern counties where winds will become
lightest/near-calm for several hours. On another note, we continue
mired in a few-days stretch of record to near-record cold...see
separate CLIMATE section below for more specifics on this.

But first, some comments about our departing winter storm before
"putting it to bed":
While we aren`t going to pretend that our storm total snow
forecast was a great one (other than a handful of western counties
including the Kearney area, most places fell at least a few inches
short), this storm "meant business" in various ways, and was NOT
without impacts. Even though only limited areas experienced true
blizzard conditions, many areas dealt with issues such as: 1) A
somewhat unexpected amount of ice/slick roads from a combination
of "flash freeze" and also steady light freezing drizzle that
mainly early Saturday morning...2) Very strong winds (very-well
forecasted) with many hours of peak gusts into the 50-65 MPH
range, resulting in several reports of downed power poles/power
outages and obviously causing considerable drifting snow
especially in those areas that received 2+". Although it`s now a
hindsight-aided statement, we hope our messaging leading up to
this storm focused more on the impacts of the very strong winds
and less-so on specific snow totals. But even so, the snow
forecast was not a complete CWA-wide bust either, as at least some
places (including the Kearney area) accumulated 4+". Moving on...

Examining the current/recent weather scene as of 4 AM...
The only real surprise overnight, and fairly minor at that, has
been the pesky persistence/continued redevelopment of snow
flurries/very light snow mainly within our eastern half, as subtle
lobes of forcing continue rotating around the backside of the
departing/powerful mid level low. Additional accumulation since
late evening has been extremely minimal (if any), but have added
isolated flurry wording to the forecast across much of the
central/east through at least sunrise to account for this.
Speaking of the big departing low, water vapor satellite imagery
and short term model initialization depict its center over the
IA/MO border, with broad ridging off to our west poised to edge
east and be our main weather influence these next 2 days before
the next system arrives (see Long Term section below). At the
surface, the main low has moved well-east into IL, while a roughly
1028 millibar ridge axis has pushed into northwest Nebraska.
While not nearly as windy as 24 hours ago, the lingering pressure
gradient continues promoting sustained north-northwest winds
generally around 20 MPH/gusts up to around 30 MPH (strongest
east/lightest west). Cloud cover trends will remain tricky through
the short term, and are already proving so, as low clouds remain
widespread in most eastern/southern counties, while a fairly
pronounced area of clearing has infiltrated especially the west-
central. Actual morning low temps are currently expected to bottom
out near-20 most areas, except for colder teens west where skies
are clearest/winds lightest.

Now looking ahead through today/tonight...

Today:
See opening paragraph for a recap of the various subtle
challenges. On the larger scale of the mid-upper levels, the slow-
moving low continues its eastward-trek into IL, while our heights
start to rise as ridging approaches from the west. At the surface,
high pressure will continue building south-southeast over our CWA.
That being said, the combination of the lingering modest pressure
gradient and some diurnal mixing will result in a breezy day, with
most areas seeing sustained north-northwest speeds average 15-25
MPH/gusts 25-35 MPH (generally highest east/lowest west). While
the vast majority of the CWA should stay precip-free today, have
lingered a small chance of flurries into mainly several northeast
counties through mid-morning, as this area seems most favored for
a continuation of some of the pesky light activity observed
already tonight. As for the rest of today`s forecast, so much
hinges on the tricky sky cover/cloud forecast. Generally speaking,
expect a fairly sharp sunnier west-cloudier east gradient, as
various model low-level relative humidity progs (including
RAP/NAM) insist that even if some clearing works into our eastern
half this morning, clouds should fill back in from the north
and/or redevelop, maintaining the west-east disparity in cloud
cover. Very generally, the dividing line between more sun west and
more clouds east should near a Kearney-Red Cloud-Beloit line much
of the day. Temperature-wise, the combo of variable sky cover and
probably to a somewhat-lesser extent variable snow cover makes
highs very tricky. In the end, opted to stick pretty close to
previous forecast, calling for roughly the northeast two- thirds
of the CWA to only top out in the 30s, with better chance for low-
mid 40s southwest where sun should be most prevalent. For sure,
errors of 5-ish degrees are very possible if the cloud forecast
doesn`t live up to these aforementioned general expectations.

This evening/tonight:
The sky cover uncertainties from today could linger into tonight.
At least for now, we are calling for no worse than a mostly clear-
to partly cloudy night all areas, as the stratus in our east-
northeast this afternoon is expected to break up/diminish this
evening. That being said, at least a few models/guidance suggest
that it could hold firmer and perhaps even retrograde southwest
somewhat with time. No matter, am calling for a precip- free night
with much lighter winds, as the surface ridge axis sets up
directly over our western/southern CWA as the night wears on.
Early in the evening, north winds will still commonly be 5-15 MPH,
but post-midnight speeds will diminish to 5-10 MPH at most, and
should actually become very light/variable along the actual
surface ridge axis in our southern/western counties. This sets up
the next possible issue: could at least patchy fog within this
ridge axis where winds will be lightest? Am sometimes skeptical of
model-suggested fog in these setups, but with at least modest snow
melt today contributing to low-level moisture enhancement tonight,
felt it was worth a medium-confidence mention of "patchy fog"
post-midnight, mainly west of a line from Ord-Hastings- Beloit.
Temp-wise, assuming that skies do in fact remain no worse than
partly cloudy, this forecaster has a decent hunch that this will
be the overall-coldest night we see the rest of the spring. Made
very little change to low temps, with most areas aimed into the
teens, with perhaps a few low 20s under any possible areas with
more clouds.

.LONG TERM...(Monday daytime through Saturday)
Issued at 457 AM CDT Sun Apr 15 2018

A ridge of high pressure will be sliding into the plains to start
the extended periods...marking the return of warmer and dry weather
to start the new work week. At the surface...the axis of the surface
ridge will be in place to start the day...making for generally light
winds Monday. With these light winds and clear skies early
on...expect the possibility for at least some patchy fog in spots to
start the week...but any fog that does form should be short lived
with a mostly sunny afternoon expected. Expect the upper level ridge
to then cross overhead early Tuesday...likely making Tuesday the
warmest day of the extended with high temperatures peaking out in
the mid 70s across our southern counties. These warmer temperatures
combined with increasing southerly winds in response to a tightening
pressure gradient...could result in near critical fire weather
concerns...especially across north central Kansas where relative
humidities will be the lowest.

Late in the day Tuesday...expect the next upper level disturbance to
emerge from the Rockies as it approaches the local area. With very
marginal instability in place...on the order of a few hundred
joules...could see an isolated thunderstorm or two develop late in
the day across some of our Nebraska counties where forcing from the
upper level low will be the strongest. Not surprisingly...SPC now how
us in an area of general thunder for this period...but looking at
the parameters...severe weather does not appear likely at this time.
Later in the evening...expect the chance for thunderstorms to
diminish as colder air works its way in from the
north...transitioning any remaining light rain into snow during the
overnight hours. At this point...any accumulating snowfall should be
limited to areas north of interstate 80...with up to one inch of
snow possible on our northernmost fringes.

As Tuesdays upper level low departs the local area...expect windy
westerly winds in its wake to combine with marginally low relative
humidity values across north central Kansas to prompt another
afternoon of near critical fire weather concerns. While both Tuesday
and Wednesday afternoons do look fairly marginal...very dry fuels
across north central Kansas do justify at least the mention of
elevated concerns in the HWO for the time being.

Brief ridging will once again make its way across the area late in
the week...helping temperatures return to near or slightly above
normal Thursday afternoon. Then...as the next upper level low over
the four corners region begins to track east...expect the chance for
precipitation to spread across the local area. With the more
southerly and consistent track of this system amongst the global
models this morning...chances for thunder have been removed and
could see a chance for some light accumulating snow during the
overnight hours Thursday night into Friday morning, again Friday
night into Saturday morning...and then finally Saturday night into
Sunday morning. While there are off and on again chances for precip
Thursday night through Sunday morning...at this time...the primary
focus appears to be Friday afternoon through Saturday
afternoon...when the main upper level low should be sliding by to
our south.

&&

.AVIATION...(For the 12Z KGRI/KEAR TAFS through 12Z Monday)
Issued at 612 AM CDT Sun Apr 15 2018

General overview:
While confidence is quite high in VFR visibility and
precipitation-free conditions (save for perhaps a few rogue
flurries mainly at KGRI), ceiling is a bit of a challenge, as KEAR
generally favors prevailing VFR through most of the period, while
KGRI generally favors MVFR, especially the first half. Wind-wise,
it will remain fairly breezy from the north-northwest through the
first 12 hours (albeit not nearly as windy as yesterday), with
sustained speeds commonly 15-20kt/gusts 20-26kt, but speeds will
steadily decrease to under 10kt this evening and remain light
through the night. Read on for more details regarding ceiling
trends...

Ceiling:
This will be tricky, especially during the first 12 hours.
Starting off, KEAR is solidly VFR while KGRI is solidly MVFR. In
general, it should remain this way through much of the day, but
even KEAR has the potential to drop back to MVFR for at least a
few hours as low stratus builds back in from the north, and this
has been handled with a TEMPO group centered from 14-18Z. Although
confidence is medium at best, will depict KGRI becoming prevailing
VFR by 00Z, but according to at least one set of guidance, MVFR
could potentially hang around on at least a temporary basis well
into tonight. Again, this is a low-confidence situation for MVFR
versus VFR, but at least confidence is rather high that any
ceiling will be no lower than MVFR.

&&

.CLIMATE...
Issued at 457 AM CDT Sun Apr 15 2018

As we continue our incredibly cold (overall) first half of April,
various cold temperature records have been broken/could yet be
broken for the April 14th-16th time frame at Grand Island and
Hastings airports, our two primary climate records sites. The
details follow:

ALREADY OCCURRED:

** Coldest HIGH temp for April 14th, and also the coldest high on
 record so late into the spring! **
- Grand Island: New April 14th record of 31 degrees (previous was
  35 in 1986). This was the latest spring occurrence of a max temp
  of 31-or-colder on record, the previous mark was 27 degrees on
  April 11, 1997.
- Hastings: New April 14th record of 30 degrees (previous was 40
  in 1993). This was the latest spring occurence of max temp 30
  -or-colder, the previous mark was 27 degrees on April 11, 1997

UPCOMING OPPORTUNTITIES:

** Coldest low temperature for April 15th (this morning) **
- Grand Island: Record is 15 in 1905...forecast is 21
- Hastings: Record is 23 in 2014...forecast is 21

** Coldest high temperature for April 15th (this afternoon) **
- Grand Island: Record is 32 in 2000...forecast is 33
- Hastings: Record is 32 in 2000...forecast is 33

** Coldest low temperature for April 16th (Monday morning) **
- Grand Island: Record is 20 in 1904...forecast is 18
- Hastings: Record is 20 in 1951...forecast is 17

&&

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

$$

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



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