Storm Prediction Center
No watches are valid as of Thu Sep 23 00:16:02 UTC 2021.
No Mesoscale Discussions are in effect as of Thu Sep 23 00:16:02 UTC 2021.
SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0238 PM CDT Wed Sep 22 2021 Valid 222000Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF EASTERN OHIO...WESTERN PENNSYLVANIA...AND NORTHERN WEST VIRGINIA... ...SUMMARY... 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
SPC Day 2 Fire Weather Outlook
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/ ...Synopsis... 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 www.spc.noaa.gov/fire for graphic product...Read more