Special Weather Statement, NWS Topeka, KS

Area Forecast Discussion
National Weather Service Topeka KS
1153 PM CDT Sun Aug 5 2018

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Monday)
Issued at 342 PM CDT Sun Aug 5 2018

Currently, cyclonic flow regime is situated over the Hudson Bay
region into portions of southern Canada.  Broad anticyclone remains
over the southern portions of the Desert Southwest region with mid
to upper ridging over the Pac Northwest. In between, a broad
fetch of southwesterly to quasi-zonal flow remains over the
central Plains into portions of the western Great Lakes region.
Speed max is evident aloft with shortwave energy moving into the
western Nebraska vicinity. Based on sounding analysis, showers and
some embedded thunderstorms blanket a good portion of Nebraska
into southern South Dakota into northwest Iowa. A weak synoptic
surface boundary that is expected to be reinforced with with
digging shortwave into Monday, and impact the forecast area late
Monday evening, is extended through southern SD into western MN
at this time.

Over the forecast area at the surface, a tight pressure gradient
remains in place in response to the lee trough over western KS into
eastern CO.  This has kept strong gusty south/southwesterly winds in
place into this afternoon.  A nice thermal ridge near the H85 level
has sampled at 22C from the 12Z TOP RAOB sounding has only increased
by a couple degrees.  This has kept a cap in place for today and
surface temps have increased to 100F at several locations including
Lawrence and Topeka with Manhattan not far behind tapping the warmer
temps aloft within a well mixed boundary layer.  Should remain dry
this afternoon and evening with apparent forcing remaining north of
the forecast area.  Short-term model guidance and HREF solutions
continued to back off from the idea of showers and storms making
their way into portions of north central KS until more near the
12Z period. It may be difficult even at that point to get much in
the way of precipitation as the sub cloud layer below 10kft is
rather dry and will take a while to saturate and by this time the
shortwave energy appears to have lifted northeast of the area.

During the day Monday, the thermal ridge will likely hold in place
acting to reinforce the cap during the early morning hours and into
the early afternoon.  Thinking is that much of the cloud cover
Monday hangs over northern areas.  This should allow areas
especially along and south of the I-70 corridor to warm into the 90s
and remain nearly as warm as today over some areas.  The surface
boundary should advance into the area as it is pushed along slowly
by a digging shortwave emerging from the northern Rockies by late
afternoon into the evening Monday.  There may be some late afternoon
storms that form if they can break the cap, but again this appears
to be uncertain if not unlikely at this time based on most
solutions.  With MLCAPE around 2000 J/kg on the higher end and
marginal deep layer shear values around the 30-35kt range, there
could be a hail threat with a storm or two.  But, would expect
mainly a strong wind threat with most storms again if they are able
to form.

.LONG TERM...(Monday night through Sunday)
Issued at 342 PM CDT Sun Aug 5 2018

Into the evening Monday and overnight is when the focus for storms
will likely increase.  Still keeping in the thought that as the
front enters the area, and a few storms that form early could pose
mainly a wind threat and still not ruling out hail.  As the upper
wave interacts more strongly with the lower levels into the late
evening and the LLJ increases to around 30kts into the boundary,
storms that move into the area from western KS could add to the
heavy rain potential over the area mainly into the midnight time
frame and overnight period.  Hard to tell for sure how heavy the
overall rain threat may be due to again soundings suggesting the
boundary layer will still have a large dry wedge in place.  But, if
storms can train then the fact that PWATs will be around 2 inch
range, there could be efficient rain producing storms.

Into Tuesday, at least the GFS does have some lingering storms
remaining in the forecast.  But, overall forcing from the upper wave
should be shifting east of the area rapidly after mid morning.  This
should tend to mitigate further storm chances from this point. With
the semi-permanent western ridge amplifying again, a period of
northwesterly flow maintains near normal temps for the middle part
of the week.  Looks like any significant precipitation chances after
this Monday/Tuesday morning round hold off for the foreseeable
future and the typical August pattern holds in place.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1150 PM CDT Sun Aug 5 2018

Expect VFR conditons through the next 24 hours. Isolated to
scattered thunderstorms may approach the terminals late Monday
evening. A southwesterly low-level jet will increase during the
early morning hours to 30-30 KTS 1500 feet above the ground.
However, surface winds should remain 8 to 12 KTS through the
night, thus the low-level shear will be in the 20 to 30 KT range
through 14Z MON.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

SHORT TERM...Drake
LONG TERM...Drake
AVIATION...Gargan

Hazardous Weather Outlook
National Weather Service Topeka KS
347 PM CDT Sun Aug 5 2018

KSZ008>012-020>024-026-034>040-054>056-058-059-062100-
Republic-Washington-Marshall-Nemaha-Brown-Cloud-Clay-Riley-
Pottawatomie-Jackson-Jefferson-Ottawa-Dickinson-Geary-Morris-
Wabaunsee-Shawnee-Douglas-Lyon-Osage-Franklin-Coffey-Anderson-
347 PM CDT Sun Aug 5 2018

This hazardous weather outlook is for east central...north
central and northeast Kansas.

.DAY ONE...This Afternoon and tonight.

There is a slight chance of thunderstorms over north central and
portions of northeast Kansas overnight.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

There is a chance of strong to potentially a severe thunderstorm
or two Monday late afternoon through Monday night. The main
threats will be heavy rainfall. Can not rule out strong winds and
possibly hail especially with late afternoon and early evening
storms on Monday.

hail threats also possible.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed through tonight.

&&

More detailed information can be accessed at...
http://www.weather.gov/top/sitrep

Special Weather Statement
National Weather Service Topeka KS
1158 PM CDT SUN AUG 5 2018

KSZ008-060530-
Republic-
1158 PM CDT SUN AUG 5 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN REPUBLIC COUNTY UNTIL
1230 AM CDT...

At 1157 PM CDT, Doppler radar was tracking a strong thunderstorm near
Byron, moving northeast at 40 mph.

Winds of 40 to 50 MPH will be possible with this storm.

Locations impacted include...
Scandia, Courtland, Republic, Munden and Narka.

LAT...LON 4000 9737 3993 9737 3974 9793 4000 9793
TIME...MOT...LOC 0457Z 240DEG 49KT 3996 9779

Gargan