Area Forecast Discussion

SYNOPSIS

Warm, dry, and breezy conditions will remain through Thursday. Moisture than increases through the end of the week, with chances for showers and thunderstorms over the weekend.

DISCUSSION

Another warm and dry day lies ahead. High pressure will continue to build over Arizona through the day. The result will be weaker pressure gradients for lighter winds, generally southwest to west at 10-20 mph this afternoon. Temperatures will warm today under the building high pressure system with many lower elevations locations approaching or surpassing the 100 degree mark. This will be especially true for the Grand Canyon where Phantom Ranch is expected to achieve its first high of 110 degrees of the year. For this reason and Extreme Heat Warning is in effect for elevations below 4000 feet in the Grand Canyon.

On Friday...High pressure building over the southwest United States and northwest Mexico will open the door to a moisture incursion across Arizona. The harbinger of this moisture increase can be noted on evening infrared satellite imagery over northwest Mexico where thunderstorm activity has been on the upswing the last few evenings. Southerly surface flow over the Gulf of California, likely helped along the by thunderstorms outflow, will push moisture into Arizona. Moisture will remain limited but a stray showers or thunderstorm is not out of the question. A bit cooler temperatures are forecast for Phantom Ranch at this time.

For Saturday through Monday...Moisture will continue to push across Arizona on Saturday and Sunday and interact with a weak trough brushing Arizona from the north. Increased moisture and slightly cooler mid-level temperatures associated with the trough will combine with daytime heating to produce widespread instability. On Saturday, the main focus of scattered showers and thunderstorms will be from the Mogollon Rim southward based on the expected northward progress of deeper moisture. By Sunday, scattered showers and thunderstorms are anticipated across all of northern Arizona. The very best chances will be over the higher terrain. It looks as if moisture will now linger into Monday. The trough axis will head east on Monday with a drier west to northwest flow developing but the dry-out will be slow enough for a few showers from about the Mogollon Rim southward.

From Tuesday onward...A drier air mass will take over with high pressure becoming reestablished over the area. Look for daytime temperatures to officially climb into the hot category for all locations with dry conditions and the usual afternoon breezes.

AVIATION...Thursday 11/12Z through Friday 12/12Z

VFR conditions. Winds becoming SW to W around 10 kts gusting 20 kts after 16Z. Returning to variable around 5 kts by 04Z.

OUTLOOK...Friday 12/12Z through Sunday 14/12Z...Primarily VFR conditions. Daytime winds SW to W 5-15 kts, subsiding to 5-10 kts each night. Slight chance of -SHRA/-TSRA Friday afternoon through Saturday morning. Scattered -SHRA/-TSRA developing from KGCN- KFLG-KSOW southward Saturday afternoon and evening with a slight chance of MVFR conditions.

FIRE WEATHER...Today and Friday

Warm weather will continue. Dry conditions today will be followed by an increasing moisture trend resulting in a very slight chance for a shower or thunderstorm on Friday. Expect southwest to west winds 5-15 mph with minimum afternoon RH of 8-15% each day.

Saturday through Monday...Warm with chances for showers and thunderstorms each day. Best chances for activity will be Saturday and Sunday afternoon, with some decline in coverage into Monday. Southwest to west winds at 10-20 mph are forecast on Saturday and Sunday, turning west to northwest on Monday. Look for minimum RH of 15-25% on Saturday and Sunday, decreasing to 10-20% on Monday.

FGZ WATCHES / WARNINGS / ADVISORIES

Extreme Heat Warning from 10 AM this morning to 8 PM MST this evening for AZZ006.