Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 190605
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
105 AM CDT Fri May 19 2017

.UPDATE...
Issued at 1122 PM CDT Thu May 18 2017

Updated the forecast this evening to decrease chances of
precipitation earlier from the southwest and increase chances
where it is raining, especially east and northeast.

&&

.SHORT TERM...(This evening through Friday)
Issued at 309 PM CDT Thu May 18 2017

Aloft: GOES WV imagery showed a sizable low centered over UT/CO
at 19Z. There were two vort maxima dumbbelling around the low. The
first was over CO and it will lift N and NW into WY tonight. The
second was over NV/UT and it will swing into NM tonight and then
lift into Wrn KS Fri eve.

Surface: A cool front extended from Ern Canada WSW thru the
GtLakes across KS to low pres over the TX Panhandle. This front
will pivot cyclonically tonight as a weak low ejects into KS. The
front should remain just SE of the CWA. This front will then
remain quasi- stationary across KS tomorrow with the main low
lingering near the TX Panhandle. Meanwhile...chilly high pres will
migrate across Srn Canada...with an axis expanding down into the
Cntrl Plns by late tomorrow.

Late this afternoon: Please follow meso discussions and outlooks
from SPC...and any possible watch/warning products from this
office.

Very little has changed from prvs thinking. The main svr wx show
will be S-SE of the CWA...with some of these storms and storm
clusters migrating N into the CWA. A very cool air mass remains
even over our N-cntrl KS counties where low clouds have retarded
daytime heating. As these storms lift N they will become
increasingly elevated...mitigating the damaging wind and tornado
threat. There will be enough elevated instability (MUCAPE up to
1500 J/kg) to support svr hail over Rooks/Osborne/Mitchell/Jewell
Counties.

Over S-cntrl Neb...believe we`re looking at general tstms with
limited potential for sub-svr hail (< 1").

Tonight: Cldy. We should see a large swath of rain lift from S-N
across the CWA along with embedded tstms. We remain very concerned
about hvy rain as the soil remains saturated over the SE 2/3 of
the CWA. Most of the rain should be out of the CWA by daybreak
Fri.

QPF: Model consensus and SREF as well as the NCAR CAM ensemble
suggest that a swath of 1-2" of rain will fall over part of the
CWA tonight. Flash flood guidance suggests 2" in 6 hrs will be
enough to initiate flash flooding.

Fri: Cldy and unseasonably chilly with blustery NE winds gusting
25- 35 mph at times. Really cut the mention of shwrs in the AM and
removed thunder altogether. We`ll be in the wake of overnight
tstms and deep moisture will be gone. The mention of AM shwrs over
S-cntrl Neb is probably overdone. Expect patchy drzl.

As the second vort max approaches...expected more tstms to
develop in the afternoon over Wrn/Cntrl KS. These storms will lift
N into the CWA once again...but with even less instability than
today. So the drzl should transition to shwrs with most tstm
activity limited to N-cntrl KS...although a couple rumbles can`t
be ruled out over S-cntrl Neb S of Hwy 6.

Again...more swaths of locally R+ are possible...especially as a
deformation zone develops/matures with the vort max lifting across
the region.

Was tempted to extend the flash flood watch back to daybreak Sat
...but will hold off and let later shifts extend if necessary.

.LONG TERM...(Friday night through Thursday)
Issued at 309 PM CDT Thu May 18 2017

The upr low referenced above will lift across the Cntrl Plns Sat
with the upr trof remaining overhead. The mean longwave trof that
has been over the W will transition over the Plns in the wake of
this low with NW flow finally becoming established by Tue as the
trof nudges E...but some guidance suggests that might not occur
til Wed. Substantial diff`s develop Thu in the last 2 runs of the
EC and the CMC/GFS. The EC runs have a ridge moving over the Plns
with a potent low over Alberta/Sask while the GFS/CMC and the GFS
ens mean maintain NW flow. The 00Z EC ens mean supports this
scenario.

As far as shorter wavelengths...models are in good agreement that
a shortwave trof will swing thru Mon-Tue...possible bringing a
few shwrs and non-svr tstms.

Temps: Sat will still be unseasonably cool. Temps will return
close to normal Sun thru Wed but will still be a little below
normal.

Frost: Sun AM has the potential for a bit of frost over the usual
cold spots in Dawson/Valley/Greeley countries...possibly more.
Bias corrected guidance suggests we may not be cold enough with
fcst temps.

&&

.AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Friday)
Issued at 100 AM CDT Fri May 19 2017

This is a complex aviation forecast with low clouds a constant
concern through the next 24hrs. Will likely see a long duration of
IFR ceiling conditions and perhaps even some shorter durations of
LIFR ceilings. Rain will end at KGRI within the next hour or two
and then we should remain mostly dry until the next round of
precipitation moves in late Friday afternoon and evening.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...Flash Flood Watch through late tonight for NEZ048-049-062>064-
     073>077-083>087.

KS...Flash Flood Watch through late tonight for KSZ005>007-017>019.

&&

$$

UPDATE...Heinlein
SHORT TERM...Kelley
LONG TERM...Kelley
AVIATION...Wesely



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