Special Weather Statement, NWS Topeka, KS

Area Forecast Discussion
National Weather Service Topeka KS
251 AM CDT Sat Aug 5 2017

.SHORT TERM...(Today and tonight)
Issued at 231 AM CDT Sat Aug 5 2017

Several modes of severe weather are possible across the
forecast area today, with a complex pattern evolving over the state.
Showers and thunderstorms starting to develop at this early morning
hour, as the low level jet continues to settle into its
southwesterly fetch and continues to increase in speed.  Good
agreement for overnight showers and storms to move east with time,
with a possible late morning lull in activity as the atmosphere then
recharges for the next, more complicated round of activity this
afternoon and into the evening hours.  Morning convection and
outflows will also have an influence on how the afternoon/eve
pattern evolves.  Of concern is considerable instability and
strengthening shear that develop, along both the warm front and
eventually the dryline and triple point somewhere over central
Kansas late this afternoon. Persistent LLJ throughout the entire day
over our area continues to ramp up the moisture available for
thunderstorms as well, aiding in the continued threat of flooding
with heavy rainfall from these storms. The initial activity through
mid day appears to be driven by the LLJ and isentropic lift
converging over the mid level front, which then later becomes
reinvigorated by the strengthening warm front lifting out of
southern Kansas into our southern CWA, as well as from the front
sliding southwestward from Nebraska and reinforced by outflow winds
from daytime convection. Heavy rainfall is the initial concern, with
the mean member of the GEFS ensemble plumes still bringing nearly
four inches of rainfall potential to the Topeka area and points east
and south. Added to the flooding threat, which continues throughout
the day and into the evening hours, is the potential for the strong
instability and shear to make its way into the counties generally
along and south of I70, bringing the risk of damaging winds, large
hail and even the threat for a tornado if the front lifts far enough
northward into our area. With all modes of severe weather possible
today, please be alert to conditions as they unfold and develop
throughout today and into the evening hours.

.LONG TERM...(Sunday through Friday)
Issued at 231 AM CDT Sat Aug 5 2017

Mid level drying behind the front will begin to shift the heavier
precipitation axis towards southeast Kansas by Sunday morning. Still
cannot rule out a few lingering showers, perhaps even light drizzle
over north central Kansas where deep low level saturation and lift
holds through the morning. Lack of dry air mixing in the boundary
layer with the sfc ridge overhead will likely keep the low stratus
around through Monday before gradually clearing occurs from north to
south.

Dry and cool conditions persist throughout the week over northeast
Kansas. Upper flow pattern changes little with the upper ridge
holding over the west and several waves rotating through the plains
and Midwest regions. By Tuesday, an elongated sfc trough translates
south and east over KS, with showers and thunderstorms developing
off the plains and tracking east along a frontal boundary. Moisture
return is limited so pops are not particularly high Tuesday and
Wednesday with respect to coverage. Uncertainty in guidance
increases Thursday onward as guidance signals a stronger mid level
trough interacting with a frontal boundary in the area. EC remains
the faster and weaker solution with an earlier onset of precip
Friday night, while the GFS is deeper and slower, resulting in
possible heavy rainfall once again for the weekend. Temps throughout
the week are well below normal with the cloud cover and no warm
advection until perhaps late in the week. Highs will generally be in
the upper 70s with lows in the 60s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday)
Issued at 1140 PM CDT Fri Aug 4 2017

Biggest uncertainty deals with how far north the warm sector
advects Saturday afternoon and whether MVFR CIGS will hang over
the terminals or not. Confidence is not great either way as models
seem to be split on how far the warm front lifts. Initially think
elevated precip and relatively dry air near the surface will keep
CIGS VFR. However probabilities for lower CIGS are likely to
increase as the afternoon progresses into the evening. This could
be from the warm front setting up south of the terminals or TS
with heavy rainfall impacting the terminals. So will include a
mention of lower CIGS. High resolution models continue to show a
break in precip by the early afternoon so will maintain this idea
in the forecast, trying to focus prevailing precip in the most
likely windows.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch from 7 AM CDT this morning through Sunday
morning for KSZ024-026-039-040-055-056-058-059.

&&

SHORT TERM...67
LONG TERM...Prieto
AVIATION...Wolters

Hazardous Weather Outlook
National Weather Service Topeka KS
335 PM CDT Fri Aug 4 2017

KSZ008>012-020>024-026-034>040-054>056-058-059-052045-
Republic-Washington-Marshall-Nemaha-Brown-Cloud-Clay-Riley-
Pottawatomie-Jackson-Jefferson-Ottawa-Dickinson-Geary-Morris-
Wabaunsee-Shawnee-Douglas-Lyon-Osage-Franklin-Coffey-Anderson-
335 PM CDT Fri Aug 4 2017

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

.DAY ONE...This Afternoon and tonight.

Scattered thunderstorms will develop tonight mainly after
midnight. Gusty winds and small hail are possible with these
storms.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Thunderstorms Saturday morning through Sunday may produce
widespread rainfall amounts of 1 to 3 inches with locally higher
amounts likely. Flash flooding is a risk from tomorrow morning
through tomorrow night. A Flash Flood Watch is in effect across
portions of east central Kansas.

There is also a risk for severe weather tomorrow in parts of
central and east central Kansas. Thunderstorms may develop in the
afternoon along a frontal boundary with the main hazards being
damaging winds and hail.

.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
406 AM CDT SAT AUG 5 2017

KSZ037-038-054-050930-
Wabaunsee-Lyon-Morris-
406 AM CDT SAT AUG 5 2017

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN MORRIS...SOUTH
CENTRAL WABAUNSEE AND NORTHWESTERN LYON COUNTIES UNTIL 430 AM CDT...

At 406 AM CDT, Doppler radar was tracking a strong thunderstorm near
Council Grove, moving northeast at 40 mph.

Dime size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Council Grove, Allen, Bushong, Dunlap and Council Grove Lake.

LAT...LON 3867 9660 3893 9620 3873 9598 3852 9647
      3852 9650
TIME...MOT...LOC 0906Z 241DEG 35KT 3864 9646