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 1 Outlook   Day 3 Outlook >
Jan 21, 2018 0700 UTC Day 2 Convective Outlook
Updated: Sun Jan 21 06:26:59 UTC 2018 (Print Version | 20180121 0700Z Day 2 shapefile | 20180121 0700Z Day 2 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Probabilistic
 Population  Cities  CWAs  Interstates  Counties  ARTCC  FEMA Regions

 Forecast Discussion

   SPC AC 210626

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1226 AM CST Sun Jan 21 2018

   Valid 221200Z - 231200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF THE SOUTHEAST STATES...

   ...SUMMARY...
   Isolated severe thunderstorms are possible as a cold front moves
   through portions of the Southeast on Monday.

   ...Synopsis...
   Mature cyclone initially centered over the central Plains will eject
   northeastward through the mid MS Valley and into the upper Great
   Lakes region as the overall upper pattern trends more progressive.
   Strong low- to mid-level flow will accompany this system, with a
   streak of 100+ kt at 500 mb arching from the base of the system
   through its eastern periphery and winds over 50 kt at 850 mb
   spreading over much of the eastern CONUS. 

   At the surface, occluded low will track into the Upper Great Lakes
   while a cold front sweeps across the Southeast and TN/OH Valleys.
   This cold front is expected to extend from the western WV Panhandle
   southwestward into the central FL Panhandle at 12Z Tuesday. Showers
   and thunderstorms are anticipated along this front but the
   increasing displacement between the better low-level moisture
   (across the Southeast) and the stronger forcing for ascent (across
   the mid MS and OH Valleys) will likely mitigate the overall severe
   potential.

   ...Southeast...
   Thunderstorms will likely be ongoing across the lower MS Valley at
   the beginning of the period. These storms will likely be in the
   midst of a weakening trend as instability wanes and surface
   temperatures reach their diurnal minimums. Some reintensification is
   possible during the afternoon, particularly across central AL, as
   the cold front continues eastward and modest daytime heating and
   moisture return occur within the downstream airmass. Instability
   will likely remain modest (i.e. MLCAPE below 500 J/kg), limiting
   updraft strength and tempering the overall severe threat, but a few
   storms capable of damaging wind gusts are possible.

   ...Central IL...
   A shortwave trough is expected to rotate through the parent system
   and into the mid MS valley during the afternoon. Forcing for ascent
   attendant to this shortwave as well as the resulting surface trough
   will provide the impetus for convection within the modestly unstable
   environment cultivated by cooling mid-level temperatures. Most of
   the storms within the resultant band of convection will be shallow
   but updrafts may occasionally be deep enough to support lightning
   production as well as small hail.

   ...VA Piedmont...
   Rapid airmass modification is anticipated ahead of the approaching
   upper system and cold front. Mid-level temperatures should be cool
   enough to support lightning but guidance varies on whether or not
   enough modification occurs to support surface-based storms. Given
   the strength of the flow across the region (cloud-layer mean wind is
   over 60 kt), any surface-based storms would pose a risk for damaging
   wind gusts. However, confidence in surface-based convection is too
   low to introduce any severe probabilities with this forecast.

   ..Mosier.. 01/21/2018

   CLICK TO GET WUUS02 PTSDY2 PRODUCT

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z

        
Top/Latest Day 1 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: January 21, 2018
Disclaimer
Information Quality
Help
Glossary
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities