textproduct: NWS Phoenix

UPDATE...Updated 00z Aviation Discussion

KEY MESSAGES

- Temperatures will remain stable several degrees above normal through Saturday followed by further cooling closer to the daily normals early next week.

- Breezy conditions will return to the area over the weekend with the strongest gusts across SE California and the Arizona high terrain.

SHORT TERM /Today through Friday/

Subtropical high pressure has fully shifted into the southern plains this afternoon while elongated troughing and weak height falls spread into the SW Conus. Deep southerly flow has imported a measure of mid/high level moisture/clouds into the region, however lower levels remain largely dessicated relegating any chance of precipitation to mountainous areas well north and east of the CWA. This troughing feature will, however, aid in mechanical mixing of higher momentum air through the boundary layer though this evening, though the strongest wind gusts will be relegated to northern Arizona. Otherwise, modest height falls along with scattered cloud cover will ensure temperatures several degrees cooler than yesterday. Weak troughing will linger over the SW Conus through Friday maintaining H5 heights around 582dm, and forcing a near persistence forecast. Confidence is very good of afternoon highs 4F-8F above normal while clearing skies and a dry airmass support comfortable overnight lows very close to the daily normals.

LONG TERM /Saturday through Wednesday/

The weather pattern through the weekend is shaping up to drive a deep Pacific trough through the Northwestern U.S. with at least one piece of energy reaching the Desert Southwest on Saturday and/or Sunday. West northwesterly dry flow is expected to dominate across our region through at least early next week keeping skies clear to mostly clear and humidities seasonably low. The main forecast concern will be the increased winds associated any passing disturbances bringing elevated to critical fire weather conditions. Differences in model timing and the track of the disturbances still remain, but based on pattern recognition it is likely to result in at least a day or two of elevated fire weather conditions. The current timing of the stronger winds favors southeast California and southwest Arizona Saturday, the Arizona higher terrain Sunday, and potentially the Lower CO River Valley on Monday.

Temperatures are expected to dip further starting around Sunday, but model spread is fairly high at this point. A deeper system could drop lower desert highs closer to 90 degrees, whereas one that somewhat bypasses to the north may only bring mid 90s for a day or two early next week. Beyond early next week, guidance mostly show a ridge building back into the region bringing gradually warmer temperatures. The latest NBM/WPC guidance shows readings potentially reaching 100 degrees again by next Wednesday.

AVIATION

Updated at 2310Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No major aviation weather concerns under some passing high cloud decks can be expected throughout the TAF period. The overall wind pattern through Thursday afternoon will follow the typical diurnal tendencies. Peak wind gusts through early this evening will generally be around 20 kts before subsiding after 02-03z. The overall wind speeds on Thursday will be weaker although some seasonal afternoon gusts into the mid to upper teens will be possible once again.

Southeast California/Southwest Arizona including KIPL and KBLH: Periods of gusty winds under generally clear skies can be expected throughout the TAF period. At KIPL, winds will generally be out of the west while at KBLH, winds will generally be out of the south to southwest. Peak wind gusts upwards of 20-30 kts will be common through the evening before weakening overnight. Winds on Thursday will be generally aob 10 kts at KBLH, however, gusts upwards of 20-25 kts are anticipated once again at KIPL by the late afternoon.

FIRE WEATHER

Hot, dry, and locally breezy to windy conditions will result in elevated fire weather potential this afternoon across the Lower CO River Valley. Wind gusts of 20-30 mph along with RHs 7-10% are expected across the Lower CO River Valley. Elsewhere today, winds will be lighter but with afternoon gusts of 15-20 mph possible. Wednesday will bring another round of breezy winds over southeast California and the Arizona high terrain with elevated fire weather conditions again a possibility. Temperatures today will be 10-15 degrees above normal dropping to 5-8 degrees above normal starting Wednesday. Winds will diminish starting Thursday, but very dry conditions will continue to prevail.

PSR WATCHES/WARNINGS/ADVISORIES

AZ...None. CA...None.