Severe Storm Outlook Narrative (AC)
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702
ACUS01 KWNS 262001
SWODY1
SPC AC 262000

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Fri May 26 2017

Valid 262000Z - 271200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR A LARGE
PORTION OF THE CENTRAL HIGH PLAINS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
CENTRAL HIGH PLAINS SLIGHT RISK...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR CENTRAL
PORTIONS OF ILLINOIS...INDIANA...AND WESTERN OHIO...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
OHIO VALLEY SLIGHT RISK...

...SUMMARY...
Widely scattered severe thunderstorms with hail and damaging gusts
are expected over the central High Plains.  Severe storms capable of
damaging winds, hail, and perhaps a tornado or two are also forecast
for parts of Illinois, Indiana, and Ohio.

...Discussion...
The only changes this forecast update are the following:
1) Have added a small 5% tornado risk and significant hail area over
parts of northeastern CO with developing storms near the Palmer
Divide.  Hodographs are forecast to enlarge this afternoon which may
lead to an area with a slightly higher tornado risk than the
remaining portion of the central High Plains.
2) Added a small significant hail area for portions of central IL to
the east of ongoing storms.

Elsewhere, the forecast remains on track.

..Smith.. 05/26/2017

.PREV DISCUSSION... /ISSUED 1116 AM CDT Fri May 26 2017/

...IL/IN/OH...
Morning satellite loops show a well-defined MCV over eastern IA.
Strong heating/destabilization is occurring along the southeast
flank of this system, with dewpoints climbing into the 60s.  By mid
afternoon, MLCAPE values of 1000-1500 J/kg are expected as far
northeast as from north-central IL into central IN and western OH.
Thunderstorms are likely to develop ahead of the MCV, with 12z CAM
solutions strongly favoring a bowing MCS moving across central IN
into western OH.  While damaging winds are likely the main threat,
increasing low-level vertical shear by late afternoon may also
contribute to some risk of a few tornadoes.  The activity should
weaken as it moves into more stable air over central OH this
evening.

...Eastern CO/Southeast WY/Western NE/Western KS...
Models remain consistent in the development of widely scattered
supercell storms from southeast WY into much of eastern CO this
afternoon and evening.  Low-level winds will be southeasterly,
providing some upslope component.  However, these low-level wind
fields will be rather weak suggesting that large hail is the main
threat.  It appears unlikely that organized storms will build as far
east into central KS as earlier forecast.

$$



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