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KEY MESSAGES

* Warm, dry, and breezy weather continues today with choppy lakes and isolated critical fire weather conditions this afternoon for W.Nevada.

* Critical fire weather concerns expected for W.Nevada due to gusty winds and dry conditions with a strong cold front on Friday and Saturday. * Temperatures cool 10-20 degrees below average over the weekend with light showers possible Friday-Saturday.

DISCUSSION

For today, forecast guidance depicts a generally westerly flow over the CWA that begins to turn a bit more west-southwesterly late this afternoon and evening as a PacNW upper trough begins to move down into the W CONUS. With this pattern above, the region looks to see one last day of above late June normal temperatures. W NV valleys will experience highs in the lower 90s this afternoon with Sierra communities ranging between the upper 70s and lower 80s. While dry conditions will prevail through the rest of today, area winds expect to increase in the late afternoon with gusts up to 25-35 mph that will last through the evening hours. A Lake Wind Advisory remains in effect for the rest of today for W NV lakes including Pyramid Lake as choppy lake waters are expected. Sierra ridge winds also look to gust up to around 60 mph through the night. With portions of the W NV seeing relative humidity dropping down to the lower teens to upper single digits in the afternoon, a few hours of elevated to isolated areas of critical fire weather conditions are expected this afternoon into the early evening. Low temperatures tonight cool down to the upper 50s to lower 60s in W NV with NE CA and the Sierra ranging between the lower 40s to the lower 50s.

For tomorrow, models have the trough moving over the CWA by early Friday morning and remaining in the W CONUS through the day. With this setup aloft, the first in a series of cold front passages looks to move through on Friday. The region sees cooler daytime high temperatures on Friday with W NV valleys in the middle 70s to lower 80s range and the Sierra communities in the middle 60s to lower 70s range. According to the latest run of the RRFS, the front will allow for a band of light showers to move through portions of W NV generally north of I-80 during the early morning that will progress into the remaining W NV portions of the CWA going through the rest of the morning. Behind it going into the afternoon, there looks to be around 20-40% chance for isolated showers north of US-50 with the higher end chances around the Tahoe Basin. Within these showers, there is a 10-15% chance for an isolated thunderstorm in the afternoon though not anticipating these storms to be severe. QPF values do not look to exceed 0.1 inches through the day though locally higher amounts could be possible from a thunderstorm producing a brief downpour. Winds increase on Friday with sustained winds of 20-25 mph gusting up to 35-45 mph in the forecast bringing another day of lake wind concerns as well as potential blowing dust near W NV desert sinks and playas. Critical fire weather conditions are also expected with these winds and thunderstorm chances on Friday in W NV (please see the Fire Weather section and the Red Flag Warning for more information). Overnight low temperatures drop to the 40s and 50s with portions of the Sierra cooling to the middle to upper 30s. Chances for showers near the OR border also increase up to around 50-60% overnight with another approaching cold front.

Forecast guidance then projects the upper trough to remain over the W CONUS on Saturday though having its axis pass over the CWA during the afternoon hours. Chances for precipitation in N Washoe, N Pershing, E Modoc and Lassen Counties will increase even more to around 55-85% during the Saturday morning hours with a 10-15% chance for isolated thunderstorms. By late afternoon and going into the night, these chances will decrease to around 25-65% while spreading south down to around US-50. The latest QPF values for Saturday range from a trace around US-50 up to around 0.3 inches in northern portions of Lassen County. Temperatures continue to cool with the secondary cold front passage causing a chilly Saturday night with lows in the 30s and 40s (some portions of the Sierra dropping below freezing). Snow levels lower to around 6.5-7.5 kft in NE CA as well which may allow higher elevations in the northern Tahoe Basin and the Warner Mountains to see a dusting of snow by Sunday morning. Mostly similar winds to those seen on the previous day will allow for similar maritime impacts (Lake Wind Advisory now continues through Saturday) as well blowing dust and fire weather concerns. One difference from Friday winds is that ridge winds are forecast to gust up to around 65-75 mph for the first half of the day.

Well-below normal temperatures continue on Sunday with some lingering morning shower chances in eastern Pershing and Churchill Counties. Area temperatures then begin to rebound as they gradually trend warmer going through next week with mostly dry conditions at least through the middle of next week. -078

AVIATION

VFR conditions are expected through the rest of today and tonight within the region. Afternoon winds gusting up to around 25-30 kts expect to subside by around 26/04-05Z. However, areas of mountain turbulence and LLWS are in the forecast going into the night for all TAF sites (with exception of KMMH) as FL100 winds of 35-40 kts are to be expected. A series of cold fronts will bring shower and thunderstorm chances to the region tomorrow and Saturday along with winds gusting up to around 35-45 kts (Sierra ridge winds up to to 55-65 kts). LLWS and mountain waves may pose hazards on these days with portions of the W NV Basin and Range seeing potential blowing dust lowering visibilities. -078

FIRE WEATHER

* Critical fire weather concerns are expected this weekend across W NV as series of potent cold fronts track through the area. Red Flag Warnings remain in effect for the Sierra Front eastward into the W NV Basin and Range Friday and Saturday.

* Elevated to isolated areas of critical fire weather conditions are expected late this afternoon in W NV as afternoon westerly gusts increase to 25-35 mph when afternoon RH drops into the upper single digits and lower teens.

* Friday will see more widespread gusty conditions as the first front moves through. West-southwesterly sustained winds of 20-25 mph with gusts of 30-35 mph are expected across both the Eastern Sierra and W NV by mid-afternoon through early evening. RH continues to trend a bit higher in the latest forecast guidance with afternoon minimums now around ~15-25% across W NV. In addition, there will be a 15-25% chances of light showers with a 10-15% chance for an isolated thunderstorm which may raise fire weather concerns.

* Critical fire weather conditions will lull Friday night into early Saturday as humidity recoveries increase to around 40-70%, but winds will remain breezy for mid-slopes and ridges.

* Saturday will see stronger wind potential as the main front sweeps through the region. Higher sustained winds of 20-30 mph with gusts of 30-40 mph are still expected with W NV afternoon RH dipping back down to ~10-20%.

* Overall, slightly higher RH values on Friday and Saturday may be negated by the stronger winds, dry fuels/grasses, and recent lightning holdover potential from last week's storms.

* Eastern Sierra fire weather zones are also expected to see these same strong winds on both days with ridgetops seeing wind gusts near 80 mph. However, fuels have not been reported to be critical and minimum RH is expected to be around 30-40%. Fuentes/078

REV Watches/Warnings/Advisories

NV...Red Flag Warning from 11 AM Friday to 11 PM PDT Saturday NVZ420.

Lake Wind Advisory from 11 AM Friday to 11 PM PDT Saturday NVZ001>004.

Lake Wind Advisory until 11 PM PDT this evening NVZ004.

Red Flag Warning from 11 AM Friday to 11 PM PDT Saturday NVZ423- 429.

CA...Lake Wind Advisory from 11 AM Friday to 11 PM PDT Saturday CAZ071- 072.