Special Weather Statement, NWS Aberdeen, SD

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
700 PM CDT Mon May 7 2018

.SHORT TERM...(This Evening through Tuesday Afternoon)
Issued at 344 PM CDT Mon May 7 2018

Two main rounds of thunderstorms will be possible through Tuesday
afternoon, both in response to an incoming shortwave which is
currently positioned across southern Montana. The first round may
develop this evening across western South Dakota by 23z and head
east through the overnight. Several CAMs are picking up on this
idea, as a combination of 1000+ J/kg of CAPE, steep low level lapse
rates and around 20 knots of deep layer shear provide a favorable
environment. By sunset, a multicell cluster of storms may be
underway across central SD. MLCAPE will have taken a nosedive, but
this cluster may be sustained due to a strengthening LLJ of 45+
knots across central/northeastern SD. A few storms may reach severe
limits at times across portions of western and even central South
Dakota, but generic to strong thunderstorms will be most likely
across the majority of the CWA with gusty winds and some small hail
being the main threats. The second main round of thunderstorms are
expected to develop near and southeast of the surface low Tuesday
afternoon/evening once the atmosphere has a chance to destabilize.
Dewpoints into the 50s, CAPE in the 1000-2000 J/kg range, and low-
level shear may once again provide a marginal environment for a few
strong to severe thunderstorms. The area of greatest concern will be
focused along a surface trough extending from the low, in central
South Dakota, southeastward into southeastern South Dakota.

.LONG TERM...(Tuesday Evening through Monday)
Issued at 344 PM CDT Mon May 7 2018

When the period opens, a low pressure system is departing the
region, resulting in decreasing precipitation chances Tuesday night
into Wednesday. Dry conditions should be in place for most of
Wednesday through Thursday before the next low pressure system moves
in, bringing more precipitation chances mainly anchored on Thursday
night into Friday. Beyond that, forecast confidence really dwindles
with an upper level rex-block pattern of sorts developing. Models
tend to mishandle system track/timing in blocky patterns. At the
moment, not all that confident that this forecast areas sees much in
the way of precipitation chances beyond Friday.

The 12Z deterministic GSM models continue to trend cooler with low
level thermal advection progs beyond Wednesday. Temperatures could
be running near to a few degrees below climo normal during the
second half of the week into the weekend. Still not seeing a lot of
support for that scenario in the NAEFS Ensemble S.A. table. 850hpa
standardized anomaly output suggests temperatures could still be one
or more standard deviations above normal beyond Wednesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 659 PM CDT Mon May 7 2018

Outside any thunderstorms, conditions will be mostly VFR through
the night. Lower visibility and cigs can be expected with
thunderstorms.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning until 7 PM CDT this evening for SDZ272-273.

MN...None.
&&

SHORT TERM...Lueck
LONG TERM...Dorn
AVIATION...TDK

Hazardous Weather Outlook
National Weather Service Aberdeen SD
330 PM CDT Mon May 7 2018

MNZ039-046-SDZ003>011-015>023-033>037-045-048-051-082030-
Traverse-Big Stone-Corson-Campbell-McPherson-Brown-Marshall-
Roberts-Walworth-Edmunds-Day-Dewey-Potter-Faulk-Spink-Clark-
Codington-Grant-Hamlin-Deuel-Stanley-Sully-Hughes-Hyde-Hand-Jones-
Lyman-Buffalo-
330 PM CDT Mon May 7 2018 /230 PM MDT Mon May 7 2018/

This Hazardous Weather Outlook is for portions of west central
Minnesota, central South Dakota, north central South Dakota, and
northeast South Dakota.

.DAY ONE...This Afternoon and Tonight

Showers and thunderstorms will develop across the area tonight. A
few storms could be strong to severe along and west of the
Missouri River this evening.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

Some strong thunderstorms are possible Tuesday and Tuesday night.
At this time, it does not appear any of the storms will be
severe.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

Telken

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN SD
651 PM CDT MON MAY 7 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0616 PM     HAIL             4 N EUREKA              45.82N 99.61W
05/07/2018  E0.88 INCH       MCPHERSON          SD   TRAINED SPOTTER

            3 INCHES DEEP IN SPOTS, BUT NONE LARGER THAN
            NICKELS.

&&

JT

Special Weather Statement
National Weather Service Aberdeen SD
607 PM MDT MON MAY 7 2018

SDZ003-080045-
Corson SD-
607 PM MDT MON MAY 7 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN CORSON COUNTY UNTIL
645 PM MDT...

At 607 PM MDT, Doppler radar was tracking a strong thunderstorm near
Thunder Hawk, or 10 miles southeast of Lemmon, moving east at 20 mph.

Dime size hail and wind gusts of 50 to 55 mph will be possible with
this storm.

Locations impacted include...
Morristown, Keldron and Thunder Hawk.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4594 10200 4595 10173 4594 10169 4564 10176
      4573 10200
TIME...MOT...LOC 0007Z 278DEG 16KT 4585 10198

Dorn

Special Weather Statement
National Weather Service Aberdeen SD
720 PM CDT MON MAY 7 2018

SDZ045-080100-
Jones SD-
720 PM CDT MON MAY 7 2018

...SIGNIFICANT WEATHER ADVISORY FOR WESTERN JONES COUNTY UNTIL 800 PM
CDT...

At 719 PM CDT, Doppler radar was tracking a strong thunderstorm over
Midland, or 23 miles northeast of Kadoka, moving east at 30 mph.

Wind gusts up to 50 mph will be possible with this storm.

Locations impacted include...
Okaton, Capa and Van Metre.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4376 10081 4376 10084 4379 10086 4378 10088
      4380 10088 4379 10090 4383 10093 4381 10095
      4385 10099 4384 10103 4386 10103 4385 10106
      4417 10105 4417 10077 4373 10077 4372 10079
TIME...MOT...LOC 0019Z 262DEG 24KT 4406 10116

Dorn