Skip Navigation Links weather.gov 
NOAA logo-Select to go to the NOAA homepage NOAA's National Weather Service   Select to go to the NWS homepage
Storm Prediction Center
navigation bar left  
  navigation bar end cap


 
USA.gov is the U.S. Government's official Web portal to all Federal, state and local government Web resources and services.

    Day 2 Outlook >
Jun 28, 2017 1300 UTC Day 1 Convective Outlook
Updated: Wed Jun 28 12:59:09 UTC 2017 (Print Version | 20170628 1300Z Day 1 shapefile | 20170628 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Tornado Wind Hail
 Population  Cities/Towns  CWAs  Interstates  Counties  ARTCC  FEMA Regions

 Forecast Discussion
   SPC AC 281259

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0759 AM CDT Wed Jun 28 2017

   Valid 281300Z - 291200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM NEAR THE
   NEBRASKA/IOWA/MISSOURI BORDER AREA TO SOUTHWESTERN WISCONSIN...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ELSEWHERE FROM
   EASTERN WISCONSIN AND NORTHERN ILLINOIS TO NORTHEASTERN COLORADO...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   SLIGHT RISK AND EXTENDING TO THE YELLOWSTONE REGION...

   ...SUMMARY...
   Severe thunderstorms with large hail, wind damage and a couple of
   tornadoes will be possible from the Mid Missouri Valley
   northeastward into the mid to upper Mississippi Valley.  Other
   severe storms may occur in the central Plains with isolated,
   marginally severe storms in the central and northern High Plains.

   ...Synopsis...
   In mid/upper levels, the intense ridge that has been dominant over
   much of the Southwest has been shunted somewhat southward, with a
   high just offshore from northern Baja, and a northward-branching
   ridge arching across the northeastern Pacific to the AK Panhandle
   and Yukon.  Downstream, part of a closed cyclone over north-central
   AB will merge with another perturbation over northern SK, while the
   rest digs southward over ID and western MT as a strong shortwave
   trough.  This will contribute to the eastward ejection of a
   lower-amplitude perturbation now over southeastern OR and northern
   NV,  reaching the western Dakotas and southeastern WY by 12Z.

   Farther east, a well-defined, nearly neutral-tilt shortwave trough
   -- augmented by several areas of convective vorticity generation --
   is evident in moisture-channel imagery over the Dakotas, NE and KS. 
   This perturbation is forecast to move east-northeastward through the
   day and weaken somewhat, reaching MN and northern/eastern IA by 00Z.
    The trough should continue to weaken overnight, with the
   primary/residual vorticity max reaching the western Lake Superior
   area by the end of the period.  Meanwhile, the longstanding
   northeastern-U.S. trough, now over New England and just offshore
   from the Mid Atlantic, will continue to eject away from the region
   and over the Canadian Maritimes. 

   At the surface, the 11Z analysis showed a low over the eastern part
   of the SD/ND border, with cold front southwestward across the Pine
   Ridge region to northeastern WY.  The low should move roughly
   eastward over the upper Mississippi Valley by 00Z, with trailing
   front southwestward across western IA and southeastern NE to
   north-central/western KS and west-central CO.  Another low should
   develop around that time over southeastern CO, at or just south of
   the intersection of the front with a lee trough extending southward
   across eastern NM.  That low should move over western KS overnight,
   as the front stalls across northern KS and southeastern NE.  The
   northern-stream surface cyclone, meanwhile, is progged to shift
   eastward and become zonally elongated across the Lake Superior
   region.

   ...Central Plains to Upper Great Lakes...
   Though exhibiting overall weakening in the past few hours, a large
   area of precip and embedded thunderstorms continues in a
   ragged/broken arc from northern MN to southwestern WI, northwestern
   MO, and eastern/southern IA, and northwestern MO, with a narrower
   area of elevated convection from central/northeastern KS to
   northwestern OK.  The KS/OK activity is progged to weaken as it
   moves eastward throughout the remainder of the morning.  The bulk of
   the northern convective area also should weaken, while moving over
   WI/MI and Lake Michigan. 

   Behind the morning convection, prefrontal air-mass moistening and
   destabilization are forecast across the outlook area today, from
   southwest to northeast, related to a combination of low-level
   theta-e advection and diabatic surface heating.  The eastward extent
   of recovery suitable for surface-based effective-inflow parcels is
   nebulous and uncertain, so a gradual gradient in severe
   probabilities will be maintained from the mid/upper Mississippi
   Valley to MI.  The most concentrated potential still appears to be
   along/ahead of the IA and perhaps southeastern NE frontal segment,
   where scattered thunderstorms should form from midafternoon through
   evening and move eastward to southeastward over parts of IL/WI.  The
   main concerns will be damaging gusts and large hail.  Additional,
   more isolated to widely scattered thunderstorms may develop over
   northern KS atop a hotter, more well-mixed boundary layer, with aid
   of frontal lift, and move northeastward across northern KS and
   perhaps southeastern NE this evening.  Scattered thunderstorms also
   are possible in an arc corresponding to the zone of stronger
   large-scale ascent ahead of the main mid/upper vorticity lobe,
   across the upper MS Valley and WI, with gusts and large hail
   possible.  

   Surface dew points in the immediately preconvective warm sector
   should be in the mid/upper 60s F near a moist axis running from
   eastern KS to southeastern NE/northwestern MO and southern/central
   IA, trending to low/mid 60s east of the MS River and mid/upper 50s
   in west-central KS.  Peak MLCAPE 2000-3000 J/kg are possible with
   those higher dew points, amidst 35-40-kt effective-shear magnitudes.
   Although SRH and deep shear will be restricted somewhat by
   southwesterly surface flow (nearly parallel to that part of the
   front), forecast hodographs still show enough low-level and deep
   shear for supercells and the risk of a couple tornadoes before storm
   modes get messier. 

   ...Central/northern High Plains/Rockies...
   Although absolute and elevation-adjusted moisture will be lacking
   relative to farther east, enough will remain to enable widely
   scattered convection this afternoon into evening, initiated in a
   regime of strong diabatic heating of higher terrain.  Activity
   should move eastward with some upscale expansion possible, as deep
   and well-mixed subcloud layers support outflow-dominant storm
   behavior.  Sufficient deep shear will exist to support an assortment
   of supercellular, multicellular, and forward-propagational bow/arc
   structures.  Though low/midlevel lapse rates will be steep across
   the entire area, buoyancy should generally weaken with northward
   extent due to weaker low-level theta-e.

   ..Edwards/Picca.. 06/28/2017

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z

        
Top/Latest Day 2 Outlook/Today's Outlooks/Forecast Products/Home
Weather Topics:
Watches, Mesoscale Discussions, Outlooks, Fire Weather, All Products, Contact Us

NOAA / National Weather Service
National Centers for Environmental Prediction
Storm Prediction Center
120 David L. Boren Blvd.
Norman, OK 73072 U.S.A.
spc.feedback@noaa.gov
Page last modified: June 28, 2017
Disclaimer
Information Quality
Help
Glossary
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities