Special Weather Statement, NWS Topeka, KS

Area Forecast Discussion
National Weather Service Topeka KS
1146 PM CDT Mon Aug 21 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Tuesday)
Issued at 257 PM CDT Mon Aug 21 2017

19Z water vapor imagery shows a low amplitude shortwave moving
through the northern plains. A weak MCV from the early morning
convection has become difficult to discern over northeast KS and
likely has sheared out. Otherwise water vapor imagery shows a plume
of mid level moisture from wester TX through northeast KS. At the
surface, a prefrontal trough was noted from northwest KS into the
eastern Dakotas with a cold front over western ND and into eastern
WY.

For tonight models still show some weak vorticity advection ahead of
the northern plains shortwave and some frontogenesis overnight with
the front. With the very moist airmass in place, showers and
thunderstorms are expected to become widespread this evening and
move through the area overnight. Models have trended slightly faster
with the frontal system and some of the high resolution models show
precip exiting the forecast area to the southeast by 7 am Tuesday.
The clouds and shower activity have slowed down the destabilization
of the boundary layer. But RAP analysis suggests MLCAPE values over
2000 J/kg beginning to develop. Deep layer shear remains a little
marginal, but look to be good enough that if a discrete storm were
able to persist it could go on to produce some severe hail and
winds. Aside from that, the main focus remains on the heavy rain
potential. With PWs still progged over 2 inches, the airmass looked
primed for heavy rainfall. Although with the model trends of a
faster progression to the frontal system, the risk for flash
flooding looks to have diminished somewhat. While the ensemble means
for QPF have also lessened, a few members continue to show the
potential for isolated heavy to excessive rain. Because of this will
maintain the flash flood watch as is.

Showers and thunderstorms should be moving southeast of the area
Tuesday morning and have POPs decreasing with virtually a dry
forecast for much of the area by noon. The stronger cold air
advection looks to hold off until late morning or early afternoon so
Lows tonight are expected to remain muggy with readings in the upper
60s to around 70. Have trended highs cooler by a degree or two with
models showing decent low level cold air advection through the
afternoon. Have forecast highs in the lower and middle 80s.

.LONG TERM...(Tuesday night through Monday)
Issued at 257 PM CDT Mon Aug 21 2017

By Tuesday night, the mid-level trough will be shifting into the
northeastern U.S. with surface high pressure sliding southward from
the Northern Plains into the central U.S.  The region will remain
under the influence of this surface high pressure and northwesterly
flow aloft through Thursday, resulting in dry conditions and
temperatures cooler than the seasonal normals with highs in the low
80s.

By Thursday night, models show a mid-level ridge briefly building
into the central U.S. ahead of a mid-level trough diving into the
Pacific Northwest.  Models are in decent agreement with showing an
embedded shortwave developing within this ridge Thursday night and
gradually tracking across the CWA Friday and Friday night.  The mid-
level trough over the Pacific Northwest will get pushed back into
Canada as a broad mid-level ridge builds across the western U.S.
Saturday through Monday.  The central U.S. will remain under
northwesterly flow aloft into early next week, with models showing
additional embedded waves developing within the mid-level flow.  As
a result, some periods of scattered showers and thunderstorms will
be possible from Thursday night into Sunday, with some isolated
precipitation possibly continuing into early next week. Temperatures
through the weekend and into early next week will remain below the
seasonal normals, with highs staying in the low 80s and low
temperatures in the low 60s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1139 PM CDT Mon Aug 21 2017

Scattered TSRA are gradually clearing KTOP/KFOE towards the east
with improving conditions to VFR. Could still see a few storms in
vicinity of the front as it passes in the 08 to 10Z time frame at
KTOP/KFOE with a mention of temporary MVFR ceilings. KMHK has a
lesser chance of seeing convection overnight. MVFR stratus should
be short lived as increasing dry air advection shunts the low
level moisture out of the area by 15Z.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 10 AM CDT Tuesday for KSZ011-012-023-024-
026-038>040-054>056-058-059.

&&

SHORT TERM...Wolters
LONG TERM...Hennecke
AVIATION...Prieto

Hazardous Weather Outlook
National Weather Service Topeka KS
1027 PM CDT Mon Aug 21 2017

KSZ008>012-020>024-026-034>040-054>056-058-059-230330-
Republic-Washington-Marshall-Nemaha-Brown-Cloud-Clay-Riley-
Pottawatomie-Jackson-Jefferson-Ottawa-Dickinson-Geary-Morris-
Wabaunsee-Shawnee-Douglas-Lyon-Osage-Franklin-Coffey-Anderson-
1027 PM CDT Mon Aug 21 2017

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

.DAY ONE...Tonight.

Training thunderstorms across portions of northeast and east
central Kansas has resulted in heavy rainfall and reports of flash
flooding earlier this evening. Flash Flood Warnings are in effect
across portions of the outlook area. Rainfall totals range from 1
to 5 inches in these areas with additional inch or two possible.
Thunderstorms through midnight may produce strong wind gusts.

Later tonight, scattered thunderstorms are expected to drop
southward along a cold front. These storms are capable of
producing heavy rainfall and the risk for flash flooding,
especially over east central and portions of northeast Kansas
where rain has fallen.

Flash Flood Watch remains in effect through Tuesday morning for
the eastern half of the outlook area.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed through tonight.

&&

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TOPEKA KS
1000 PM CDT MON AUG 21 2017

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

0945 PM     HEAVY RAIN       CORNING                 39.66N 96.03W
08/21/2017  E4.00 INCH       NEMAHA             KS   TRAINED SPOTTER

            STORM TOTAL SINCE 9:45 PM CDT.

&&

JP

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TOPEKA KS
1006 PM CDT MON AUG 21 2017

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

1003 PM     FLOOD            TOPEKA                  39.05N 95.68W
08/21/2017                   SHAWNEE            KS   LAW ENFORCEMENT

            10" OF STANDING WATER REPORTED AT 10TH AND
            TOPEKA.

&&

SMB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TOPEKA KS
1008 PM CDT MON AUG 21 2017

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

1003 PM     FLASH FLOOD      TOPEKA                  39.05N 95.68W
08/21/2017                   SHAWNEE            KS   LAW ENFORCEMENT

            10" OF STANDING WATER REPORTED AT 10TH AND
            TOPEKA. ...CORRECTION...

&&

SMB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TOPEKA KS
1102 PM CDT MON AUG 21 2017

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

0921 PM     TSTM WND DMG     EMPORIA                 38.40N 96.18W
08/21/2017                   LYON               KS   PUBLIC

            RELAYED VIA PHOTOS ON SOCIAL MEDIA. 10 INCH
            TREE BRANCH SPLIT FROM THE MAIN TRUNK. RADAR
            ESTIMATED TIME.

&&

JP

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TOPEKA KS
143 AM CDT TUE AUG 22 2017

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

0120 AM     FLOOD            2 S OTTAWA              38.59N 95.26W
08/22/2017                   FRANKLIN           KS   LAW ENFORCEMENT

            MINOR STREET FLOODING ALONG 15TH STREET
            BETWEEN OAK AND MULBERRY STREETS.

&&

Special Weather Statement
National Weather Service Topeka KS
229 AM CDT TUE AUG 22 2017

KSZ023-024-026-038>040-054>056-220800-
Wabaunsee-Shawnee-Lyon-Pottawatomie-Jefferson-Douglas-Jackson-
Franklin-Osage-
229 AM CDT TUE AUG 22 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN FRANKLIN...
JEFFERSON...SHAWNEE...DOUGLAS...EASTERN WABAUNSEE...NORTHERN OSAGE...
SOUTHEASTERN POTTAWATOMIE...SOUTHERN JACKSON AND NORTHEASTERN LYON
COUNTIES UNTIL 300 AM CDT...

At 228 AM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 6 miles northeast of Lawrence to near Keene.
Movement was south at 30 mph.

Wind gusts up to 50 mph will be possible with these storms.

Locations impacted include...
Topeka, Lawrence, Baldwin City, Carbondale, Valley Falls, Rossville,
Oskaloosa, Eskridge, Tecumseh, Eudora, St. Marys, Richland, Dover,
Silver Lake, Auburn, Overbrook, Burlingame, Perry, McLouth and
Meriden.

This includes the following highways...
 Interstate 70 between mile markers 336 and 355.
 Kansas Turnpike between mile markers 146 and 205.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with these storms, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3863 9607 3934 9618 3942 9527 3942 9518
      3897 9519 3896 9517 3898 9516 3896 9508
      3898 9508 3884 9505 3876 9506
TIME...MOT...LOC 0728Z 351DEG 25KT 3903 9519 3894 9601