SPC Day 2 Fire Weather Outlook

By Newsroom America Feeds at 13 Sep 15:26

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0223 PM CDT Wed Sep 13 2017 Valid 141200Z - 151200Z ...Portions of KS, the OK/TX Panhandle, and northwest OK... A slight southward expansion was made to the Elevated area into the eastern TX Panhandle. While minimum RH values may be only marginally reduced across the Elevated region (i.e., 20-25%), sustained winds near 20 mph atop at least marginally receptive fuels warrants continuation of the Elevated fire weather risk across the area. See previous discussion below for a more detailed information. ...Southern Idaho... Locally elevated fire weather conditions may also develop in the vicinity of the Snake River Valley during the afternoon, as primarily terrain-enhanced gusty winds overlap receptive fuels. However, uncertainty remains regarding the amount of boundary-layer drying, with the lowest RH values tending to remain removed from the strongest winds. Furthermore, some potential for wetting rainfall exists today (Wednesday), which may render fuels less receptive. Thus, an Elevated area was not introduced with this forecast package due to the aforementioned limiting factors. If trends in RH values suggest greater low-level drying near the strongest winds then an Elevated area may be needed in a future update. ..Elliott/Gleason.. 09/13/2017 .PREV DISCUSSION... /ISSUED 0114 AM CDT Wed Sep 13 2017/ ...Synopsis... Lee surface troughing will occur over the central High Plains, south of a frontal zone extending from the upper Mississippi Valley to the northern Plains. This will be encouraged by mid-level flow attaining more of a zonal component over the central Rockies vicinity. Modest lift well downstream of a mid-level cyclone -- becoming absorbed into a long fetch of southwesterly flow aloft peripheral to an amplifying northwest states trough -- will further enhance the lee surface troughing. These factors will support a relatively enhanced pressure gradient over portions of the central states. ...Portions of KS, the OK Panhandle, northwest OK... The aforementioned pressure gradient is expected to support southerly to south-southwesterly surface winds of 15-22 mph with higher gusts. Despite the southerly flow, moisture return will be very limited on Day-2/Thursday -- owing to the antecedent reinforcement of dry air over the south-central states (south of the remnants of Tropical Cyclone Irma). As temperatures warm into the lower to middle 90s, RH should fall to 19-24 percent (lowest readings in western KS and the adjacent OK Panhandle). Given the drying of fine fuels related to the lack of recent precipitation, elevated fire-weather conditions are anticipated. However, given the lack of an even drier air mass, RH is not expected to become sufficiently low amidst strong winds for Critical designation. ...Please see www.spc.noaa.gov/fire for graphic product... Read more



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