Severe Thunderstorm Warning 208, NWS Des Moines, IA

876 
WWUS53 KDMX 101632
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
1132 AM CDT TUE JUL 10 2018

IAC147-151-101645-
/O.CON.KDMX.SV.W.0208.000000T0000Z-180710T1645Z/
Pocahontas IA-Palo Alto IA-
1132 AM CDT TUE JUL 10 2018

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1145 AM CDT
FOR NORTHWESTERN POCAHONTAS AND SOUTHWESTERN PALO ALTO COUNTIES...

At 1132 AM CDT, a severe thunderstorm was located over Silver Lake,
or 13 miles southwest of Emmetsburg, moving southeast at 25 mph.

HAZARD...Ping pong ball size hail and 60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...People and animals outdoors will be injured. Expect hail 
         damage to roofs, siding, windows, and vehicles. Expect wind 
         damage to roofs, siding, and trees.

Locations impacted include...
Laurens, Silver Lake, Rush Lake, Lost Island Lake, Ruthven, Mallard,
Ayrshire, Havelock, Plover, Curlew and Lost Island Lake State Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Continuous cloud to ground lightning is occurring with this storm.
Move indoors immediately. Lightning is one of nature's leading
killers. Remember, if you can hear thunder, you are close enough to
be struck by lightning.

&&

LAT...LON 4288 9451 4278 9485 4286 9492 4324 9491
TIME...MOT...LOC 1632Z 318DEG 23KT 4300 9489 

HAIL...1.50IN
WIND...60MPH
 
$$

Boksa

Area Forecast Discussion
National Weather Service Des Moines IA
628 AM CDT Tue Jul 10 2018

.SHORT TERM.../Today through Tonight/
Issued at 325 AM CDT Tue Jul 10 2018

Weak surface boundary has made it to the I80 corridor early this
morning.  Some drier air has begun to enter far northern Iowa,
otherwise little difference is noted on either side of the front
other than the wind shift. The slightly cooler airmass will ease
across the northeast half of the forecast area today with some minor
relief to highs today along with slightly lower dewpoints.  Farther
to the south and west, temperatures and dewpoints will be similar to
Monday and anticipate heat index values in the mid 90s again today
across the southwest third of so of the forecast area.  Other
concern is some of the CAMs bring the convection across North Dakota
close to the northeast corner of the forecast area toward midday on
leading edge of moisture gradient.  While the mention of storms have
been left out of the forecast in those locations, near term trends
will need to be monitored closely for the eventual evolution of
these storms.

For tonight, the best forcing and low level moisture transport
remains well west and north of the forecast area.  Western and
southern areas will be the warmest where higher dewpoints and
proximity to the thermal ridge will keep readings higher.  More
pleasant conditions are forecast to remain in the northeast where
slightly lower dewpoints/temps will persist into tonight.

.LONG TERM.../Wednesday through Monday/
Issued at 325 AM CDT Tue Jul 10 2018

Upper level ridging will continue to be over the area on Wednesday
with surface high pressure over the Great Lakes. This will allow for
a return to southerly flow that will promote another very warm day
with a bit of a bump upwards in humidity. High temperatures will be
4 to 5 degrees above normal with heat index values in the 90s.

As an area of low pressure tracks across the Canadian prairies with
a cold front trailing to the south over the northern states, the
upper level ridge will weaken. The front will lose its upper level
support later on Thursday leaving this boundary as a focus for
showers and storms. Clouds will increase Wednesday night with
chances of rain and storms increasing on Thursday. As has been noted
in previous discussions, the severe potential is less than the
locally heavy rain potential at this point. The limiting factor to
the severe is the lack of robust shear with the boundary being over
southern Minnesota at peak heating with strong instability. Focus
for any severe threat will be damaging wind gusts with isolated
large hail given the shear parameters. The greater concern will be
Thursday night as the boundary slowly moves into northern Iowa where
the atmosphere will be moisture laden. Precipitable water values
will be above normal with the 9/12z NAEFS specific humidity values
in the 90th or higher percentile over the area. Warm cloud depths
will be greater than 13000 feet with warm rain processes dominating.
While mean flow will be 20 to 30 knots, the flow will be largely
parallel to the boundary indicating a possibilitiy of training
storms. Latest WPC outlook highlights northern Iowa with a marginal
risk of excessive rainfall for this reason. While there will be
breaks in the rainfall, the overall set up for the possibility of
locally heavy rainfall will persist into Friday and may linger
into Saturday as the boundary sinks farther south into the state
with perhaps weaker mean flow these two days.

A new area of low pressure will move across the Canadian prairies
bringing a cold front into the state either late Sunday or more
likely Monday. This would bring a round of showers and strong storms
across central Iowa. The GFS continues to be the more progressive
solution driving the front into Missouri with chances for showers
and storms ending by early next week. Meanwhile, the ECMWF keeps
storm chances as it is the slower and less progressive solution. At
this time range, will stick with the initial blended guidance for
Monday into early next week.

&&

.AVIATION.../For the 12Z TAFS through 12Z Wednesday morning/
Issued at 628 AM CDT Tue Jul 10 2018

Widespread VFR conditions for much of the period with some
scattered cumulus today as well as high cirrus drifting overhead.
Surface winds will be light and eventually swinging around to the
east southeast tonight.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

SHORT TERM...Cogil
LONG TERM...Ansorge
AVIATION...Cogil

Hazardous Weather Outlook
National Weather Service Des Moines IA
959 AM CDT Tue Jul 10 2018

IAZ004>007-015>017-023-024-111500-
Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo-
Pocahontas-Humboldt-
959 AM CDT Tue Jul 10 2018

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Today and tonight

Thunderstorms will track through north central Iowa this morning
and into early afternoon. Severe weather threat is low, but small
hail and gusty winds are possible.

River Flood Warnings are in effect for parts of the Des Moines
River basin. Please refer to the National Weather Service website
at weather.gov/desmoines for further details.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

River Flood Warnings will remain in effect for parts of the Des
Moines River basin likely into the first part of this weekend.
Please refer to the National Weather Service website at
weather.gov/desmoines for further details.

Thunderstorm chances will increase Thursday into Friday lingering
into this weekend. There is a risk of strong to severe storms
over northern Iowa later Thursday with the main threats being
damaging wind gusts, locally heavy rainfall, and large hail. The
risk for locally heavy rain will remain possible on Friday.

.SPOTTER INFORMATION STATEMENT...

Spotters activation is not needed at this time.

IAZ025>028-033>039-044>050-057>062-070>075-081>086-092>097-111500-
Wright-Franklin-Butler-Bremer-Sac-Calhoun-Webster-Hamilton-Hardin-
Grundy-Black Hawk-Crawford-Carroll-Greene-Boone-Story-Marshall-
Tama-Audubon-Guthrie-Dallas-Polk-Jasper-Poweshiek-Cass-Adair-
Madison-Warren-Marion-Mahaska-Adams-Union-Clarke-Lucas-Monroe-
Wapello-Taylor-Ringgold-Decatur-Wayne-Appanoose-Davis-
959 AM CDT Tue Jul 10 2018

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Today and tonight

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Thunderstorm chances will increase Thursday into Friday lingering
into this weekend. There is a risk of strong to severe storms
over northern Iowa later Thursday with the main threats being
damaging wind gusts, locally heavy rainfall, and large hail. The
risk for locally heavy rain will remain possible on Friday.

.SPOTTER INFORMATION STATEMENT...

Spotters activation is not needed at this time.