textproduct: NWS Flagstaff

SYNOPSIS

Dry and warmer conditions will continue today. A pair of winter weather systems is expected to impact northern Arizona from late Monday through much of next week, bringing gusty winds and chances for rain and snow.

DISCUSSION

High pressure was centered over the Arizona/New Mexico border during the early morning hours, heading eastward. The remainder of the week will be highlighted by a series of shortwave troughs which will deliver colder temperatures, windy conditions and good chances for mountain snow and lower elevation rain. Driving will become difficult and hazardous at times through the coming week due strong crosswinds and snow accumulation on roads. Make sure and plan your travels accordingly.

For today...High pressure will move east of Arizona in advance of a trough approaching from over the Pacific Ocean. Weather conditions will remain dry with mild daytime temperatures. However, clouds will be on the increase in advance of the Pacific trough, with south to southwest winds at 5-15 mph gusting to 25 mph as surface pressure gradients tighten.

On Monday and Tuesday...The first in a series of shortwave troughs will move from west to east across Arizona later on Monday through Tuesday. In advance of the trough, during the day Monday, look for southwest winds at 15-25 mph gusting to 35-45 mph as pressure gradients strengthen further. These strong winds are likely to continue Monday night through Tuesday. As a result, a Wind Advisory is in effect for portions of Arizona on Monday and may be extended through Tuesday if model trends continue. As moisture increases and upper dynamics move in Monday night it is expected that widespread showers will develop. Snow levels start out in the 7,000-8,000 foot range but then fall to 5,500-6,500 feet by midday Tuesday. Models are showing that this initial trough will tap into more moisture than we were looking at 24 hours ago. Elevations above 6000 feet are expect to see general snowfall accumulation of 3-6 inches (which is a slight increase over previous forecasts) with higher amounts over the San Francisco Peaks and highest elevations of the Kaibab Plateau. Likewise, lower elevations will see 0.20-0.45 inches of rainfall which is also an increase due to the additional moisture.

From Wednesday into Thursday...The next shortwave trough will move in during the day Wednesday. Winds will remain strong on Wednesday, generally from the southwest at 15-25 mph gusting to 35-45 mph, especially along and northeast of the Mogollon Rim. Winds quite a bit lighter by Thursday as the trough heads eastward. This will be colder system as it will approach from a more northerly direction. As a result, the snow level looks to start out in the 5,500-6,500 foot range but then drop to 4,000-5,000 feet before the trough exits the area on Thursday. The shortwave trough will have a little further north trajectory than the Monday/Tuesday trough. As a result, the best snow accumulations are forecast to be from near Happy Jack northwestward over the higher terrain. The forecast is for general snow accumulations of 4-8 inches at elevations above 6,000 feet across this area with up to a foot over the very highest mountain locations. Lower elevations are forecast to see 0.10-0.25 inches of rainfall.

Looking at Friday into next weekend...Forecast models are beginning to lock on to another fast moving shortwave trough for Arizona on Friday which would deliver additional mountain snow and lower elevation rain. Our confidence in this feature is low at this time so we will wait a day or two to provide details. Still looking like fair weather moves in for next weekend.

AVIATION...Sunday 15/06Z through Monday 16/06Z

VFR conditions. Winds light and VRB overnight, becoming S/SW 5-15 kts with gusts 20- 25 kts after 18Z. Winds subsiding to around 5 kts after 02Z.

OUTLOOK...Monday 16/06Z through Wednesday 18/06Z...VFR conditions through 00Z Tuesday, with MVFR/IFR conditions developing RA/SN from west to east. Periods of LIFR in +SN/BLSN over the higher terrain late Monday-early Tuesday. Winds S/SW 15-25 kts with gusts 30-40 kts each day.

FIRE WEATHER...Today and Monday

Dry and warm conditions today with temperatures 5-10 degrees above average. Monday will be windy and dry through the day, but rain and snow showers begin spreading from west to east by late evening into the night as the next storm system approaches. Snow levels are 7000-8000 feet by the onset of precipitation and drop into the night. Winds S-SW 10-15 mph gusting to 25 mph today, increasing to SW 15-30 mph with gusts 35-45 mph on Monday. Minimum afternoon RH values 20-35% today, increasing to 20- 40% Monday.

Tuesday through Thursday...Periods of widespread rain and snow showers continue as a series of weather disturbances pass through. Accumulating snow or wetting rains are likely through the period. Gusty conditions will continue, winds SW 15-30 mph with gusts 35-45 mph on Tuesday and Wednesday. Winds decrease Thursday, becoming W 10- 15 mph gusting to 25 mph.

FGZ WATCHES/WARNINGS/ADVISORIES

Wind Advisory from 11 AM to 8 PM MST Monday for AZZ006>008-012- 013-015-016-038-039.