Administrators NorthGeorgiaWX Posted September 30 Administrators Share Posted September 30 SPC Day 3-8 Fire Weather Outlook Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0334 PM CDT Mon Sep 30 2024 Valid 021200Z - 081200Z Fire weather concerns will persist intermittently through the extended period across the western half of the CONUS. Long-range ensemble guidance continues to show a general ridging pattern over the southern half of the country, which will continue to favor stronger mid/upper-level flow along the U.S./Canadian border. This regime will favor seasonal to above-normal temperatures for the Plains into the West and mostly dry conditions. Consequently, dry fuels will likely be maintained and gradually expand in coverage for many locations. Fire weather concerns will emerge as shortwave troughs embedded within the mean zonal flow (and their attendant surface lows/fronts) propagate across the northern CONUS. ...D3/Wednesday - Southern Wyoming... Strong zonal flow is expected to persist across the northern CONUS through late D3/Wednesday. This will maintain a downslope flow regime into the WY Basin with afternoon RH values forecast to reach into the teens to low 20s. Deterministic and ensemble guidance show a signal for 15-25 mph winds, and with ERCs generally near the 90th percentile, elevated to critical fire weather conditions appear likely. ...D3/Wednesday - Coastal Southern CA... Upper ridging over the Great Basin combined with a weak coastal low will promote a modest offshore flow regime across southern CA. Unseasonably hot temperatures will continue to dry fuels and maintain very dry conditions. Localized elevated fire weather conditions are possible - mainly within the higher coastal terrain - late Wednesday into early Thursday morning. ...D5/Friday - northern Great Basin... Latest water-vapor imagery reveals a broad upper trough over the central Pacific, which is forecast to reach the West Coast by D5/Friday. Stronger flow overspreading the Pacific Northwest will promote downslope winds and surface pressure falls in the lee of the Cascades/northern Sierra Nevada. While run-to-run trends continue to show some variability regarding the strength of the winds, recent European solutions, which typically under-forecast winds, align with latest GEFS wind probabilities and suggests fire weather concerns may emerge during D5/Friday afternoon. ...D6/Saturday - northern Rockies/High Plains... The upper trough that is forecast to reach the Pacific Northwest on D5/Friday is expected to migrate into the northern Plains through D6/Saturday. As this occurs, lee cyclogenesis is probable and should support strengthening low-level pressure gradient winds both ahead of and behind the primary surface trough/cold front. While some uncertainty remains regarding the degree of RH reductions across the region, very dry fuels already in place (ERCs well above the 90th percentile) combined with a strong wind signal hint that a fire concern is possible. Further adjustments/expansions into the Plains are possible as guidance continues to come into better alignment. ..Moore.. 09/30/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more View the full article Quote Link to comment Share on other sites More sharing options...
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