Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 262358

Area Forecast Discussion
National Weather Service Hastings NE
658 PM CDT Thu Apr 26 2018

.SHORT TERM...(This evening through Saturday daytime)
Issued at 433 PM CDT Thu Apr 26 2018

Once the modestly-strong north winds die down this evening, we
are looking at a guaranteed dry, less-windy and, by most folks
standards, a seasonably-pleasant 48 hours. That being said, it
will be a little breezy each of the next 2 days (just not as
windy as today). These Friday breezes and warmer temps could
support some near-critical fire weather conditions, but see
separate Fire Weather section below for all further discussion of
this. As for low temps tonight, it could get JUST cold enough to
support some patchy/localized frost development, but our office
will not be issuing any formal frost/freeze headlines until after
May 1st given the recent cold/slow start to the growing season.

Reviewing the current/recent weather scene as of 330 PM:
No big surprises today by any means, although if anything it has
been a touch windier than expected, as there have been a
surprising number of sporadic sustained speeds of 30+ MPH/gusts of
45+ MPH at various local airport sites (including a 49 MPH gust at
Grand Island). Although there could have been a few sprinkles
earlier in the day here or there, the preceding night shift
correctly downplayed any true rain potential today, as a few
models from 24 hours ago were certainly proven over-done. In the
mid-upper levels, water vapor satellite and short term model data
clearly reveal a quick-moving/moisture-starved/southwest-northeast
oriented shortwave trough passing directly overhead at this time.
To its south, our south-southeast counties are still seeing some
enhanced mid-high level cloud cover, while steady clearing to
nearly complete sunshine has invaded our northwestern two-thirds.
At the surface, have already mentioned the fairly strong north
winds firmly in place behind the cold front currently positioned
along a line from the TX Panhandle to central IA. Temp-wise, it
appears that most places will end up a degree or two warmer than
early-morning expectations, with most places topping out in the
63-68 range.

Now looking ahead in the forecast through these next 48 hours...

This evening/tonight:
Most importantly, the gusty north winds will steadily subside
especially between 7-9PM, and in fact most of the night will
feature speeds no more than 5-10 MPH as direction transitions from
northerly to westerly. In the mid-upper levels, we will be under
the influence of the eastern fringes of an expansive ridge
centered over the Intermountain West. This will promote nearly
crystal-clear skies. If not for the light-but-steady westerly wind
component, would be more concerned about low temps dropping
farther, but kept them similar to previous forecast (and similar
to last night) with most places bottoming out 34-38.

Friday daytime:
Although it will be a bit breezy especially in our northeast half,
overall a pleasant day. Dry northwesterly flow continues aloft,
as we remain on the downstream side of the western ridge, and this
will provide plentiful sunshine. A weak cold front will gradually
sink southward into the area over the course of the day,
gradually turning winds from more westerly in the morning, to more
northerly by late afternoon/early evening. In roughly our
northeast half, sustained speeds by late morning/afternoon will
average 15-20 MPH/gusts 20-25 MPH, with values roughly 5 MPH
lighter in southwest zones. Nonetheless, this is a slight increase
from previous forecast. Temp-wise, the widespread sun and good
low level mixing will support warmer temps than today (despite the
weak front moving in), and have highs aimed mainly 72-76.

Friday night:
Quiet, guaranteed dry weather continues under benign northwesterly
flow aloft. The weak cold front will continue its trek south-
southwest as surface high pressure builds into the Dakotas/MN.
Winds will average around 10 MPH much of the night, as direction
gradually shifts from more northerly to more easterly with time.
Although still on the cool side for late April, overnight lows
should hold up very slightly milder than tonight in most places,
and have a range from mid-30s north to around 40 far south.

Saturday daytime:
This is the last guaranteed dry period of the 7-day forecast, as
we see one last day dominated by ridging in the mid-upper levels.
Thanks to the "back door" cold front that passes through late
Friday into Friday night, temps will take a slight step back, with
highs ranging from mid-60s northeast to lows 70s far southwest.
Wind-wise, it will start to become breezy especially by mid-late
afternoon from the east-southeast, with sustained speeds averaging
10-15 MPH east and 15-20 MPH west (with gusts to around 25 MPH).

.LONG TERM...(Saturday night through Thursday)
Issued at 433 PM CDT Thu Apr 26 2018

General overview of this 5-day period:
For those who read this discussion yesterday afternoon, please
note that there have been no big changes in the "big picture", as
our three big stories center around various chances for
thunderstorms mainly Sunday night-Wednesday (some possibly strong
to severe?), strong south gradient winds especially Sunday-
Monday and also our first pronounced truly warm/mild stretch of
both days/nights this spring. Will focus on these topics in a bit
more detail:

1) Rain/thunderstorm potential:
For sure, the late weekend through mid-week time frame turns more
active, but there are still a ton of question marks regarding just
how much so. In the mid-upper levels, the short story is that a
large-scale western CONUS trough will eject several disturbances
into the Central Plains in southwesterly flow aloft, each of which
will be capable of producing at least isolated convection. One
small change from the previous forecast is that we now have a
chance for rain showers (no thunder at at this time) starting as
early as late Saturday night into Sunday morning, in association
with the very first small-scale wave that enters the picture.
Thereafter, instability increases enough that thunderstorms become
a better bet with the various rain chances smattered throughout
mainly the Sunday night through Wednesday night time frame. As is
almost always the case 3+ days out, models still vary considerably
on the finer details of exactly where rain/thunderstorms will
form, and to some extent when, but especially the evening-
overnight hours on both Monday/Tuesday (and perhaps even
Wednesday) will need monitored for at least strong/if not severe
thunderstorm potential. Would like to provide more detail on this,
but it`s just too soon to have enough confidence to do so.
Officially, the overnight SPC Day 4-8 outlook BARELY kept our CWA
out of the severe threat areas for Tuesday/Wednesday, and while it
currently seems that the overall-highest chances for severe storms
should focus slightly to our south-through-east, later outlooks
will most likely include parts of our CWA in at least low-end
severe probabilities. So much yet to sort out here.

2) Strong south winds:
Especially between the Sunday daytime and Monday night time frame,
south winds will crank up area-wide, in response to deepening
surface low pressure to the west. As is typical at the Day 3-4
range, our forecasted speeds are probably still not high enough,
but pattern recognition suggests that sustained speeds of 25-35
MPH/gusts 40+ MPH are a good bet on both of these days, and this
strong wind mention has been introduced to our HWO. It could still
be quite breezy into Tuesday, but models currently suggest a cold
front will start to invade, which if nothing else will shift
direction more northerly and likely decrease speeds somewhat.

3) Warmer/more "humid" weather overall:
Although warm-weather lovers will obviously have to contend with
the aforementioned strong winds especially Sunday-Monday, for
sure this will be our warmest stretch of the spring so far. Sunday
highs are aimed into the 70s, with Monday the overall-warmest day
with widespread upper 70s to low 80s. As the cold front works
through mid-week, highs will likely ease back into the 60s/lower
70s in most areas Tuesday-Thursday. Overnight lows will definitely
be noticeably milder than we`ve seen this spring. Values Saturday
night will hold up in the 40s area-wide, with widespread 50s to
even near 60 Sunday and Monday nights. Tuesday and Wednesday
nights should be a bit cooler, but still well into the 40s most


.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday)
Issued at 640 PM CDT Thu Apr 26 2018

Wind gusts will be the biggest concern for this early evening
until lapse rates and surface pressure gradients decrease. An
increase of wind speed is expected by late morning Friday as
low-level lapse rates increase again, but will not be nearly as
strong as wind gusts from this afternoon.


Issued at 433 PM CDT Thu Apr 26 2018

Although we do not currently anticipate any outright-critical
conditions during the next 7 days that might require Warning
issuance, there are a few afternoons that bear watching for at
least near-critical conditions:

1) Friday afternoon: This latest forecast has increased the
potential for meeting near-critical parameters, due to the combo
of relative humidity (RH) values dropping into the 20-25 percent
range and west-northwest winds gusting 20-25 MPH. The greatest
overlap of these wind/RH parameters appears to focus within
roughly the northeast half of the CWA. Because this is now in the
short term, a mention has been added to the Hazardous Weather
Outlook (HWOGID).

2) Sunday and Monday afternoons: Although the lowest/critical RH
values are expected to focus at least slightly west-southwest of
our CWA, we`ll need to keep an eye on mainly our far western
counties where RH values could a least flirt with 25 percent. Wind
speeds are not in question, as southerly gusts of 30+ MPH are
quite certain.


Issued at 1217 PM CDT Thu Apr 26 2018

..This is currently projected to be the SECOND-COLDEST APRIL on
record at Grand Island/Hastings..

Based on observations from the first 25 days and forecast
expectations from today through month`s end, both Grand Island and
Hastings airports (our two primary long-term climate data sites)
are on pace to have the 2nd-coldest April on record, trailing only
April 1920 in the record books. For those possibly hoping that we
might set a new record for coldest April this month, the above-
normal temperatures anticipated Friday-Monday are expected to
"wreck" this opportunity, and slide April 2018 into 2nd place.
Stay tuned for more specific info on this next week.




SHORT TERM...Pfannkuch
LONG TERM...Pfannkuch
FIRE WEATHER...Pfannkuch
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