SPC Forecast Products Storm Prediction Center

  • SPC May 22, 2019 2000 UTC Day 1 Convective Outlook
    on May 22, 2019 at 7:47 pm

    SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0243 PM CDT Wed May 22 2019 Valid 222000Z - 231200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST OK INTO CENTRAL MO... ...SUMMARY... Severe thunderstorms are forecast this afternoon into evening from Oklahoma into Missouri and central Illinois. Tornadoes, large/damaging hail and severe gusts all are possible. ...20z Update... Note: Severe probabilities are being increased along the I-44 corridor across OK. Latest satellite imagery depicts a subtle but potentially significant mid-level short-wave trough ejecting across the TX South Plains within an otherwise rising height field. It is becoming increasingly clear this feature will play an important role in the evolution of deep convection across OK over the next few hours. High-PW air mass has surged northwest into OK with lower 70s surface dew points across much of the central/eastern parts of the state. Strong heating along the western fringe of this air mass appears to be instrumental in recent thunderstorm development over Tillman County OK. 1813z Arcadia (NE OKC Metro) sounding exhibited minimal inhibition and reflected the approaching short wave at mid levels. Based on recent radar/satellite trends, latest thinking is ongoing storms in southwest OK will continue to mature and lift northeast along the I-44 corridor. The potential for very large hail and tornadoes will be noted with this activity as it spreads downstream. ..Darrow.. 05/22/2019 .PREV DISCUSSION... /ISSUED 1126 AM CDT Wed May 22 2019/ ...OK to IL... Given latest model guidance and observational trends, have opted to upgrade to MDT risk along a narrow corridor from northeast OK into central MO. Consensus continues to grow in model guidance that several discrete supercells will develop along this corridor this afternoon and evening, as low-level moisture streams northward and shear profiles rapidly strengthen. The primary negative indicator of a more significant severe weather event involves the large scale pattern, and the large midlevel height rises that are occurring throughout the Plains. However, latest water vapor loop and model guidance suggest very subtle shortwave troughs embedded in the upper flow, with one currently over southwest OK. This feature would arrive into the risk area around peak heating, potentially helping initiation. Forecast soundings suggest an environment favorable for strong tornadoes and very large hail and if discrete supercells can form. It is unclear how far southwest the development will occur into central OK. Several 12z CAM solutions suggest 1-2 storms near OKC that could be severe if they develop, with a conditional risk of significant tornadoes and hail. However, confidence in persistent thunderstorms that far southwest is lower than farther northeast. Storms that form over central MO will spread eastward into central/northern IL during the evening, with the continued risk of supercells capable of large hail, damaging winds, and a few tornadoes. It is unclear how rich the low-level moisture will be ahead of the storms, but shear profiles will be quite favorable in this area. Read mor […]

  • SPC Tornado Watch 211 Status Reports
    on May 22, 2019 at 7:30 pm

    WW 0211 Status Updates STATUS FOR WATCH 0211 HAS NOT BEEN ISSUED YET Read mor […]

  • SPC PDS Tornado Watch 211
    on May 22, 2019 at 7:30 pm

    WW 211 TORNADO OK TX 221930Z - 230300Z URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 211 NWS Storm Prediction Center Norman OK 230 PM CDT Wed May 22 2019 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Southwest and Central Oklahoma Western North Texas * Effective this Wednesday afternoon and evening from 230 PM until 1000 PM CDT. ...THIS IS A PARTICULARLY DANGEROUS SITUATION... * Primary threats include... Several tornadoes and a few intense tornadoes likely Scattered large hail likely with isolated very large hail events to 3 inches in diameter possible Scattered damaging wind gusts to 70 mph possible SUMMARY...Isolated intense thunderstorms are expected to affect the watch area this afternoon and early evening. Any storm that persists will pose a risk of strong tornadoes, very large hail, and damaging winds. The tornado watch area is approximately along and 60 statute miles north and south of a line from 25 miles south of Altus OK to 45 miles south southeast of Chandler OK. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU1). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. && AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 3 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 24030. ...Hart Read mor […]

  • SPC MD 733
    on May 22, 2019 at 7:13 pm

    MD 0733 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR SOUTHWEST INTO CENTRAL AND NORTHEAST OK Mesoscale Discussion 0733 NWS Storm Prediction Center Norman OK 0212 PM CDT Wed May 22 2019 Areas affected...southwest into central and northeast OK Concerning...Severe potential...Watch possible Valid 221912Z - 222045Z Probability of Watch Issuance...60 percent SUMMARY...Monitoring for signs of convective initiation and sustained thunderstorm development. A tornado watch is being considered in the next 1-2 hours. DISCUSSION...Latest surface analysis indicates a triple point over southwest OK with a dryline extending southward into west TX. A maritime warm front has progressed northward across the I-44 corridor in OK and a decaying cold front is located from north-central OK northeastward through southeast KS into west-central MO. Surface observations show temperatures rising into the lower 80s over much of OK south of the warm front with dewpoints in the lower 70s. The warmest conditions are located over southwest OK where convective temperatures are close to being breached. A 17z Norman, OK special sounding showed moderate buoyancy but the boundary layer had not destabilized appreciably. Since then, a very unstable airmass has developed over central OK with 3500 J/kg MLCAPE estimated by objective analysis. KTLX VAD data over central OK indicates a supercell wind profile is in place with 50kt effective shear and around 100 m^2/s^2 0-1km SRH. Model guidance indicates the LLJ will gradually strengthen this afternoon into the early evening. Forecast hodographs become most favorable for low-level mesocyclones/tornadoes during the 5pm-8pm period with a classic sickle-shape structure and 0-1km SRH increasing to 200 m^2/s^2. Models are suggestive of a more isolated coverage from near OKC and south/southwest with widely scattered storms possible farther northeast into northeast OK. Although the severe risk is conditional, high-end severe weather would likely accompany any intense supercell. ..Smith/Hart.. 05/22/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TSA...ICT...OUN... LAT...LON 34269902 34669919 35349907 37059625 37089543 36579489 35929496 34119774 34079864 34269902 Read mor […]

  • SPC Day 2 Fire Weather Outlook
    on May 22, 2019 at 6:26 pm

    SPC Day 2 Fire Weather Outlook Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0125 PM CDT Wed May 22 2019 Valid 231200Z - 241200Z Primary change with this update was to trim portions of the Elevated area over the higher terrain near the Sacramento Mountains in New Mexico, as cooler temperatures (e.g., mid/upper 50s) at higher elevations should keep RH reductions above regional thresholds, with only brief/spotty Elevated conditions now expected. The Elevated fire weather area was also expanded into western portions of the Trans-Pecos in far west Texas, as high-resolution guidance suggests RH values at or below 15%, sustained wind speeds of 15-25 mph, and at least marginally receptive fuels across this area. See previous discussion below for more information. ..Elliott.. 05/22/2019 .PREV DISCUSSION... /ISSUED 0200 AM CDT Wed May 22 2019/ ...Synopsis... The entrance region of a mid-level jet will linger across portions of New Mexico on D2/Thursday as an upper closed low moves into the northern Rockies. At the surface another lee trough will develop in the southern High Plains. Dry southwesterly flow across New Mexico will lead to afternoon RH values of 5-20%. While surface winds of 20-30 mph will be possible in northern New Mexico, the departing mid-level jet core into the central Plains will mean lighter winds of 15-20 mph in much of southern New Mexico. Due to the reduced surface winds over the most receptive fuels, only elevated fire weather concerns can be expected across the highlighted area. Should pockets of more receptive fuels exist, locally critical fire weather will be possible in those locations. ...Please see www.spc.noaa.gov/fire for graphic product... Read mor […]