Special Weather Statement, NWS Kansas City, MO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1249 PM CDT TUE AUG 7 2012

...UPDATED AVIATION DISCUSSION...

.DISCUSSION...

Have raised afternoon temperatures by a few degrees owing to
presence of h8 thermal ridge overhead, plenty of sun and a boundary
layer that is once again drying out and allowing for super-adiabatic
lapse rates to occur near the surface. Also bumped up pops over far
northeast KS and parts of far nw MO due to new convection which
sprouted over northeast KS since 1645Z. None of the short range
convective models are handling the convection over KS. Using the
overall LSX local WRF, HRRR and NAM20 model trends suggest
convection should have a difficult time moving too far owing to a
very weak steering flow and relatively stable downstream airmass.

MJ

&&

.PREV DISCUSSION...
/337 AM CDT Tue Aug 7 2012/
Today through Thursday...

The main forecast challenge in the short term is precipitation
chances for this afternoon through Wednesday across the region. Both
the NAM and GFS break out convection this afternoon across eastern
Nebraska, where a subtle surface boundary creates minor lift for
initiation. The front will likely become more diffuse as it travels
southward, which will combine with an increasing capping inversion
to make precipitation unlikely in our area through late this
evening. However; in case thunderstorms that do develop track into
our far northwest this evening, edged some slight chances into our
far northwest before 06z Wednesday.

Currently, the highest probability for rainfall looks to be across
our far west after 06z Wednesday. A decent low level jet develops
across central Kansas and eastern Nebraska around midnight, while a
slight southeasterly turn to the low level wind field brings a bit
more moisture into play across the region. These ingredients could
support thunderstorm development or the enhancement of ongoing
convection in southeast Nebraska and northeast Kansas, which could
form an MCS that tracks through northwest Missouri early Wednesday
morning. A shortwave trough will approach the region around daybreak
on Wednesday, turning steering winds to the west southwest and
pushing any weakening activity across southern Iowa and far northern
Missouri, likely exiting the region around mid morning. As a result,
there will be a marginal severe weather threat across our northwest
early Wednesday morning if a well-formed MCS can develop and move
through the region.

By Wednesday afternoon, the shortwave will drop southeastward
through northern Missouri, possibly supporting broadly scattered
showers and thunderstorms across the CWA during the daytime. Without
appreciable surface focus for initiation and the mixing of low-level
moisture during the afternoon, the probability of precipitation
remains somewhat low, but is worth mentioning with decent midlevel
forcing. Models are a bit inconsistent on the speed of the wave and
its trajectory, but precipitation chances should taper off Wednesday
night from west to east, ending Thursday morning.

Temperatures during the period will depend on the coverage of clouds
and precipitation, but should be warmest today with mixing of mid
20s C 850 temperatures and only scattered midlevel clouds, then
cooler Wednesday and Thursday as the trough over the east deepens
and temperatures aloft cool.

Laflin

Medium Range (Friday - Monday)

The pattern during the extended forecast seems pretty slow to evolve
leaving the region in prolonged northwest flow. this should keep
temperatures at or possibly even below normal for the period. While
models show some precipitation chances over the weekend due to an
advancing shortwave, latest ECMWF shows our chances diminishing.
With atmospheric moisture limited, low to no pops is probably the
right choice. For now will go with the 15-20 pops the model blend
init gave, but wouldn't be surprised to see us go dry for the
weekend over the next few days if the trend continues.

Bailey

&&

.FIRE WEATHER...

Much like Monday afternoon, very dry conditions are expected again
Tuesday afternoon as winds turn to the south at 5 to 10 knots.
Relative humidity values will once again fall to around 20% but
light winds will preclude widespread red flag conditions. However,
given the severity of the drought conditions, any increase in winds
will lead to substantially higher fire danger threats. Will continue
to issue an SPS for the elevated fire danger threat.

MJ

&&

.AVIATION...

For the 18z TAFs, expect VFR conditions overall during this forecast
period. Short range models not handling the current upstream
convection very well. However, weak steering flow suggests this
activity will be slow moving and pass west of KSTJ and likely not
reach the KMCI/KMKC terminals. Owing to much uncertainty in timing
and lack of confidence later in the forecast will use VCTS to
indicate potential of nearby storms and await better modeling or
established radar trends and amend if necessary. Better bet for
convection will most likely occur after 18z Wed.

MJ

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&

WFO EAX

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
1258 PM CDT TUE AUG 7 2012

KSZ025-057-060-102>105-MOZ001>008-011>017-020>025-028>033-037>040-
043>046-053-054-081115-
ATCHISON KS-MIAMI-LINN KS-DONIPHAN-LEAVENWORTH-WYANDOTTE-JOHNSON KS-
ATCHISON MO-NODAWAY-WORTH-GENTRY-HARRISON-MERCER-PUTNAM-SCHUYLER-
HOLT-ANDREW-DE KALB-DAVIESS-GRUNDY-SULLIVAN-ADAIR-BUCHANAN-CLINTON-
CALDWELL-LIVINGSTON-LINN MO-MACON-PLATTE-CLAY-RAY-CARROLL-CHARITON-
RANDOLPH-JACKSON-LAFAYETTE-SALINE-HOWARD-CASS-JOHNSON MO-PETTIS-
COOPER-BATES-HENRY-
1258 PM CDT TUE AUG 7 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHWEST...NORTH CENTRAL AND
WEST CENTRAL MISSOURI...AS WELL AS EXTREME EASTERN KANSAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT

THE FIRE DANGER WILL AGAIN BE ENHANCED THIS AFTERNOON AS TEMPERATURES
RISE INTO THE UPPER 90S TO 103 DEGREES AND RELATIVE HUMIDITY
DECREASES INTO THE 20 TO 25 PERCENT RANGE. ALTHOUGH WINDS WILL BE
LIGHT...THE COMBINATION OF DRY AIR AND VERY DRY VEGETATION WILL MAKE
FIRE DIFFICULT TO CONTAIN.

THERE IS A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON
OVER EXTREME NORTHEAST KANSAS AND ADJACENT FAR NORTHWEST
MISSOURI...AND THEN LATER TONIGHT NORTH OF THE MISSOURI RIVER. WHILE
SEVERE THUNDERSTORMS ARE NOT ANTICIPATED...AN ISOLATED STRONG STORM
COULD PRODUCE GUSTY WINDS UP TO 50 MPH THIS AFTERNOON OR EARLY
EVENING.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

SCATTERED THUNDERSTORMS ARE POSSIBLE OVER THE ENTIRE REGION ON
WEDNESDAY...AND AGAIN ON SATURDAY NIGHT AND SUNDAY. THE SEVERE
WEATHER THREAT WILL REMAIN LOW DURING THESE PERIODS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED.

MJ

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
228 PM CDT TUE AUG 7 2012

MOZ002-072000-
NODAWAY MO-
228 PM CDT TUE AUG 7 2012

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN NODAWAY COUNTY UNTIL 300
PM CDT...

AT 224 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 6 MILES NORTHEAST OF SKIDMORE...OR 6 MILES WEST
OF MARYVILLE...MOVING EAST SOUTHEAST AT 25 MPH.

WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS STORM.

LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...
  MARYVILLE...ARKOE AND BARNARD.

THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND
TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS... FOR ADDITIONAL
INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE.

LAT...LON 4034 9467 4015 9479 4025 9508 4026 9507
      4026 9511 4027 9513 4038 9501
TIME...MOT...LOC 1928Z 290DEG 20KT 4031 9496

MJ

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
320 PM CDT TUE AUG 7 2012

MOZ002-011-012-072045-
ANDREW MO-HOLT MO-NODAWAY MO-
320 PM CDT TUE AUG 7 2012

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN ANDREW...
SOUTHWESTERN NODAWAY AND EASTERN HOLT COUNTIES UNTIL 345 PM CDT...

AT 318 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM NEAR MAITLAND...OR 6 MILES NORTHEAST OF MOUND
CITY...MOVING SOUTH AT 5 MPH.

HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 50 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN.

LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...
  MOUND CITY AND GRAHAM.

THIS WILL IMPACT

 I-29 BETWEEN MILE MARKERS 73 AND 85.

TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND
UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED
ROADWAY.

LAT...LON 4007 9492 3998 9520 4023 9529 4030 9507
TIME...MOT...LOC 2019Z 339DEG 6KT 4018 9514

CUTTER