SPC Day 1 Fire Weather Outlook

By Newsroom America Feeds at 18 Mar 2018

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1032 AM CDT Sun Mar 18 2018 Valid 181700Z - 191200Z ...EXTREMELY CRITICAL FIRE WEATHER AREA FOR PORTIONS OF FAR SOUTHEAST NEW MEXICO INTO THE TEXAS SOUTH PLAINS VICINITY... ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE CENTRAL AND SOUTHERN HIGH PLAINS... Minor adjustments have been made to the critical and elevated areas mainly across eastern portions of the OK/TX Panhandles. Current cloudiness should mostly move out of the region by around 17-18z, allowing for stronger heating and mixing of the boundary layer. However, guidance suggests thunderstorms will develop near the dryline from southwest KS into parts of the OK/TX Panhandle by 22-23z (see Day 1 Convective Outlook for severe weather details). The critical area has been adjusted to be in line with the expected position of the dryline by mid-to-late this afternoon. An elevated area remains east of the dryline owing to strong winds and favorable fuel conditions, despite RH values not expected to fall below roughly 20-30 percent across the eastern OK/TX panhandles into far western OK. Further west across eastern NM and western TX, a large area of critical to extremely critical fire weather conditions are expected to develop in the next few hours. Deep boundary layer mixing will allow for very strong surface winds as an intense midlevel jet streak of 80-90 kt overspreads the region. RH values should fall into the upper single digits to 10 percent across the extremely critical area, with values 10-15 percent elsewhere in the critical. For more details, see previous discussion below. ..Leitman.. 03/18/2018 .PREV DISCUSSION... /ISSUED 0155 AM CDT Sun Mar 18 2018/ ...Synopsis... A shortwave trough will move eastward from the Southwest to the southern High Plains through this evening, with a belt of very strong (70-100+ kt) mid-level flow overspreading eastern NM into west TX and the TX/OK Panhandles by late this afternoon. Large-scale lift preceding this shortwave trough will promote the deepening of a surface low over southeastern CO today. A Pacific cold front associated with the shortwave trough will sweep eastward across the southern High Plains through the day, likely reaching into southeastern KS and far western OK into western north TX by late this evening. Preceding this front, a dryline should extend southward from the surface low across the southern High Plains, and an eventual merging of the front/dryline should occur across the eastern TX/OK Panhandles by late this afternoon. ...Portions of the Southern/Central High Plains... As the surface pressure gradient strengthens and enhanced mid-level winds reach the surface with mixing of the boundary layer, strong/gusty southwesterly to westerly winds of 20-40 mph will develop today across parts of the southern/central High Plains. Higher gusts to 50-60 mph may also occur. RH values will likely fall into the 7-15% range across much of this region due to downslope warming/drying processes even though temperatures will be reduced behind the cold front passage. Critical conditions appear most likely from eastern NM into west TX, much of the TX/OK Panhandles, far southeastern CO, and extreme southwestern KS. Elevated conditions should occur across a broader portion of the southern/central High Plains, with low-level moisture return across much of OK and central TX generally limiting the eastward extent of substantial fire-weather concerns. High-end critical to extremely critical conditions should be realized across parts of far eastern NM into the TX Panhandle and west TX for a few hours this afternoon beneath the core of the mid-level jet. Here, sustained winds of 30-40 mph now appear likely, with RH values around 7-10% through peak diurnal heating. Confidence in these meteorological conditions has increased enough to introduce an extremely critical area across this region where the strongest winds are expected this afternoon. Very dry fuels and ongoing drought across this region will allow for extreme rates of fire spread given the forecast strength of the winds. Short-term guidance is now in better agreement regarding how far east elevated/critical conditions will develop across southwestern KS and the eastern TX/OK Panhandles along a composite dryline/cold front early this evening. Have therefore made minor changes to the elevated and critical delineations across these areas. Elevated to critical conditions may continue through the evening and early overnight hours across the southern High Plains as winds remain strong/gusty behind the cold front passage. ...Please see www.spc.noaa.gov/fire for graphic product... Read more



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