Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 260536
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
1236 AM CDT Wed Jul 26 2017

.SHORT TERM...(This evening through Wednesday night)
Issued at 358 PM CDT Tue Jul 25 2017

The main concern in the short term is the potential for
thunderstorms overnight tonight through Wednesday night.

Overall today has panned out as expected with highs in the 90s
and dewpoints in the upper 60s to low 70s. Heat indices are
beginning to reach above 100 for a few sites and should peak
between 100 and 105 across much of the area late this afternoon.
Winds have been gusty at times out of the south at 15 to 25mph
which will hopefully

Thunderstorm chances return tonight with a line expected to move
in from the west around midnight. Severe potential is somewhat in
question, but the initial line has the potential for strong to
severe wind gusts and small hail. The latest NAM NEST is hinting
at some spotty shower/tstorm development ahead of the line across
areas south of I-80 but currently have things dry until the main
line comes through.

Rain showers will linger through the overnight hours, with a
narrow but strong low level jet developing overnight ahead of the
advancing cold front that should help keep precip around into the
early morning hours. Models are recently hinting that things may
clear out for a few hours allowing for more destabilization to
occur allowing for the potential for redevelopment Wednesday
afternoon especially across our southeastern zones. Any storms
that do develop have the potential to be strong to severe,
although we are currently not outlooked. These will then track off
to the southeast out of the area by late Wednesday night.


.LONG TERM...(Thursday through Tuesday)
Issued at 358 PM CDT Tue Jul 25 2017

General overview of this 6-day period: It`s probably somewhat of
a good news/bad news situation depending on one`s viewpoint, as
while it will be trending somewhat cooler it also looks to remain
relatively dry with no "big soakers" for those wanting/needing
decent rains.

By far the number 1 story is temperatures: In contrast to the
slightly above to occasionally well-above normal heat/humidity
that has defined most of July so far, the last several days of the
month into the first day of August should actually average near-
to- slightly-below average for a change. We are not talking
"refreshingly cool" by any means, but we are talking several
consecutive days withs highs "only" in the 80s across the majority
of our county warning area (CWA), with perhaps some low 90s
occasionally brushing into a few of our typically-hotter
southwestern counties at times. Low temperatures look to follow a
similar trend, with most nights at least cooling into the low-mid
60s, as opposed to the upper 60s- mid-70s lows that have defined
much of July so far in many areas. And last but not least in this
department, dewpoint temperatures and resultant humidity levels
look to be more tolerable as well with more in the way of low-mid
60s instead of the more oppressive 70s much of especially the
northeast half of the CWA has endured on many recent days.

Precipitation-wise: Technically speaking, this latest forecast
package now features more in the way of pesky/small/fairly
uncertain rain/thunderstorm chances (PoPs) than the previous one
did, as at least some portion of the CWA features at least a 20
percent (slight chance) during each day/night period from Friday
night through Tuesday. At this time, the very highest PoPs are
only 30-40 percent (and limited in area at that), so certainly
nothing that looks overly widespread/soaking for beneficial rains
at this point (beyond tonight/tomorrow`s halfway decent chance
outlined in the Short Term section above). The same goes for
severe thunderstorm chances. While this type of summer pattern is
certainly conducive to at least isolated/occasional strong to
severe storms, there does not appear to be anything very
organized/widespread in the Friday-Tuesday time frame. Backing up
to the nearer-term Thursday daytime-Friday daytime periods, these
36 hours look to be about as "guaranteed dry" as July can possibly
get, as we catch a glancing blow of Canadian high pressure, also
responsible for our aforementioned slightly cooler and drier
airmass.

Briefly covering the large-scale weather pattern, the vast
majority of this time frame will be dominated by a large-scale
ridge over the western/southwest CONUS and a large-scale trough
over the eastern states, placing our region under fairly
persistent/consistent northwest-flow aloft, featuring the passage
of intermittent/fairly weak disturbances.

With the main points covered, will conclude with some day-to-day
specifics for those interested...

Thursday daytime-night: Although there is probably the slightest
chance that a rogue sprinkle/shower could linger slightly past
sunrise in our extreme southeast CWA behind the departing system
from Wednesday night, have maintained a dry forecast CWA-wide for
now. Overall, the day should feature plentiful sunshine and
northeast winds around 10 MPH. Did nudge up high temps very
slightly from previous, but still "only" talking 83-87. Weak high
pressure will dominate the region Thursday night, and as long as
skies remain clear, lows temps should make it all the way down
into the 59-62 range most areas, which would mark the overall-
coolest night most places (including the Tri Cities) have seen in
at least 2 and a half weeks!

Friday daytime-night: Breezes transition to out of the east-
southeast behind departing surface high pressure, but high temps
look very similar to Thursday with mainly mid-upper 80s. While
confidence remains high in a dry day and probably evening too, the
late night hours feature the return of some "iffy" small
shower/thunderstorm chances.

Saturday daytime-Sunday night (the weekend): Don`t get too
concerned about the fairly persistent small PoPs, as "most" of the
weekend should remain dry in most areas, with continued high
temps mainly mid-upper 80s and lows in the low-mid 60s. The latest
GFS especially is suggesting perhaps a somewhat better chance of
rain mainly late Saturday night, but this has fairly limited
support from the ECMWF.

Monday-Tuesday: Overall much the same story as the weekend as we
head into August, so again: highs mainly mid- upper 80s and some
intermittent low rain chances. There are hints (especially per the
GFS) that a somewhat stronger mid level wave could bring a more
promising hope for more widespread rain just beyond the current
official 7-day forecast around next Wednesday, but this scenario
currently has very little support from either the ECMWF or
Canadian at this time, and appears to be somewhat of an outlier.

&&

.AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Wednesday)
Issued at 1236 AM CDT Wed Jul 26 2017

Significant Wx: LLWS until roughly 12Z. Sct TSRAs. Cool frontal
passage Wed.

Overnight: Generally VFR but sct TSRAs could result in brief IFR
VSBYs and G35 kts. Winds S-SSE 10-15 kts with ocnl G20 kts outside
of TSRAs. Confidence: Medium. Watch for amendments as we monitor
trends.

Wed: VFR but there could be some low clds around 12Z-16Z...
gradually lifting to around 4K ft. There is significant
uncertainty on how much SHRA/TSRA activity will be around based on
multiple model fcsts. WSHFT with passage of cool front.
Confidence: Low

Wed Eve: Probably VFR to start. Any SHRA/TSRA activity ends early
then MVFR CIGs may move in. NNE winds 10-15 kts. Confidence:
Medium

&&

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

$$

SHORT TERM...Petr
LONG TERM...Pfannkuch
AVIATION...Kelley



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