Blue Flower

Outlook (Main)

Storm Prediction Center
SPC Forecast Products
  1. No watches are valid as of Thu Sep 23 00:16:02 UTC 2021.
  2. No Mesoscale Discussions are in effect as of Thu Sep 23 00:16:02 UTC 2021.
  3. SPC 2000Z Day 1 Outlook
    Day 1 Outlook Image
    Day 1 Convective Outlook  
    NWS Storm Prediction Center Norman OK
    0238 PM CDT Wed Sep 22 2021
    Valid 222000Z - 231200Z
    The greatest potential for damaging to severe thunderstorm winds and
    a few tornadoes today will be over parts of Ohio, West Virginia and
    western Pennsylvania.
    ...20Z Update...
    ...Upper OH Valley...
    Recent surface analysis places a deepen low near the OH/WV/PA border
    intersection, along the leading edge of a cold front pushing
    eastward across the OH Valley. Overall instability remains modest
    ahead of the front, but still sufficient for updrafts deep enough to
    produce lightning. Additionally, the clearing across southwest PA
    has allowed temperatures to climb into the low 80s, fostering
    locally higher buoyancy in this region. Vertical shear remains
    strong and the threat for embedded bowing structures capable of
    damaging wind gusts and a tornado or two is expected to persist
    throughout the afternoon into the early evening. 
    ...VA and Carolinas...
    As mentioned in recently issued MCD #1776, a couple damaging gusts
    may accompany the stronger storms through the remainder of the
    afternoon. However, any severe threat is expected to isolated and/or
    brief given the limited vertical shear.
    ..Mosier.. 09/22/2021
    .PREV DISCUSSION... /ISSUED 1107 AM CDT Wed Sep 22 2021/
    ...Upper OH Valley...
    A deep upper trough is moving slowly eastward across parts of
    IL/IN/KY today, with an associated surface cold front extending from
    central OH southward into east TN and northern GA.  A pocket of
    partly cloudy conditions has developed ahead of the front from
    central WV into eastern OH and western PA.  Continued afternoon
    heating/destabilization will yield MLCAPE values of 1000-1500 J/kg. 
    A surface low along the front over OH will deepen today as it tracks
    into western PA.  Backing/strengthening low-level winds ahead of the
    low will enhance convergence and aid in the development of
    thunderstorms along the cold front.  Shear profiles will be rather
    strong, posing the risk of supercell and bowing structures capable
    of damaging winds and a few tornadoes.  Storms should weaken by
    early evening as they move into more stable air over central PA.
    ...VA and Carolinas...
    The aforementioned surface cold front will move across the mountains
    of western VA/NC this afternoon.  Warm and humid conditions ahead of
    the front will result in thunderstorm development.  Low and
    deep-layer wind fields in this region are weaker than farther north,
    suggesting storms will be less organized.  Nevertheless, isolated
    intense cells may develop, with locally damaging winds possible.
    Read more
  4. SPC Day 2 Fire Weather Outlook
    Day 2 Fire Weather Outlook Image
    Day 2 Fire Weather Outlook  
    NWS Storm Prediction Center Norman OK
    0255 PM CDT Wed Sep 22 2021
    Valid 231200Z - 241200Z
    Added an elevated area for the southern Plains. More widespread
    winds of 15 to 20 mph seem likely with relative humidity of 13 to 18
    percent. In addition, recent fuel guidance shows ERC values locally
    above the 90th percentile indicating pockets of critically dry fuels
    are likely present.
    ..Bentley.. 09/22/2021
    .PREV DISCUSSION... /ISSUED 0144 AM CDT Wed Sep 22 2021/
    Morning surface observations from the Canadian Prairies show weak
    surface pressure falls already occurring as a lee low begins to
    develop. This feature is expected to continue deepening today before
    shifting eastward Thursday, funneling cold air into the northern and
    central High Plains as a result. Breezy and dry conditions behind
    this cold front may support a low-end fire weather concern.
    Increasing southerly winds across the Southern Plains may likewise
    support elevated conditions, but the probability of sustained 15+
    mph winds appears too low for highlights at this time. 
    ...Central High Plains...
    Recent ensemble guidance shows reasonably high probabilities for
    15-20 mph winds immediately behind the dry cold front as it shifts
    southward along the High Plains. A combination of dry air advection
    and a weak downslope component will likely result in widespread RH
    reductions into the teens and low 20s. While elevated wind/RH
    combinations appear likely, rainfall over the past 72 hours has
    reduced fuel readiness for many locations. Dry conditions today may
    help cure fine fuels to a degree, and highlights may be introduced
    in subsequent outlooks if fuel conditions sufficiently deteriorate.
    ...Please see for graphic product...
    Read more