Forecast Discussion
000 FXUS65 KTWC 082128 AFDTWC Area Forecast Discussion National Weather Service Tucson AZ 228 PM MST Mon Mar 8 2021 .SYNOPSIS...A storm system slowly moving in from the northwest will bring gusty winds at times and a steady cooling trend through the week. We may also see a few valley rain and mountain snow showers, with best chances late Thursday into late Friday. && .DISCUSSION...Southeast Arizona is caught in between high pressure south and east of our area, and a strong approaching weather system currently just off the Pacific Northwest coast. As this system slowly digs into the region, our winds will increase with some gusty afternoons over the next several days. We don`t expect them to be strong enough for wind headlines, but there are definite fire weather concerns as outlined in the fire weather section below. The evolving split is rather deep with a good track bringing the system into Arizona Friday. The high amplitude flow isn`t very progressive with a building ridge through the Gulf of Mexico and less higher latitude support as the system approaches from the northwest the second half of the week. With slower timing we should have enough of a fetch to bring in enough moisture for a chance of valley rain and mountain snow showers by late Thursday or Thursday night into Friday or Friday night. Precip amounts are not expected to be significant, with valley locations looking to stay under 1/3 of an inch at this point. Cool enough for snow levels as low as 4500 feet, with 1 to 3 inches above 6000 feet. Some clearing from the west next weekend as the low shears into the front range of the Rockies and the central plains. However, ensemble mean height anomalies suggest continued large scale troughiness through the region at least the first half of next week. && .AVIATION...Valid through 10/00Z. BKN-OVC clouds generally AOA 15K-18k ft MSL thru 09/18Z, then clearing skies from west to east. SFC wind SLY/SWLY SFC at 8-18 kts and gusts up to 25 kts (with the strongest wind east of Tucson) thru 09/02Z. Aft 09/02Z, diminishing wind and SFC wind less than 12 kts between 09/04Z and 09/17Z. SFC wind increasing again aft 09/17Z, and SWLY SFC wind at 15-25 kts and gusts to 25-35 kts by 09/20Z. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Dry conditions are expected into the middle of this week, with a slight chance of precipitation in the White Mountains starting on Tuesday and then across the rest of southeast Arizona Thursday night into Saturday. High temperatures will be 3-7 degrees above normal Tuesday, with much colder temperatures overspreading southeast Arizona Thursday through Saturday. Gusty 20-foot wind speeds are expected Tuesday into Saturday. Critical fire weather conditions are expected Tuesday south and east of Tucson and therefore a Red Flag Warning has been issued for portions of Santa Cruz and Graham counties and all of Cochise county from 1 pm to 7 pm MST Tuesday for strong and gusty southwest winds, low relative humidity values and a high fire danger. There will be the possibility of localized critical fire weather conditions being met during the afternoon and early evening hours in areas south and east of Tucson again Wednesday, with borderline conditions hanging on over Cochise County Thursday as the colder air overspreads the area and higher RH values follow. && .TWC WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 1 PM to 7 PM MST Tuesday for AZZ151-152- 154. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
NWS TWC Office Area Forecast Discussion