textproduct: NWS Phoenix

UPDATE

06Z Aviation Discussion

KEY MESSAGES

- Well above normal temperatures will persist early this week resulting in areas of minor HeatRisk across lower elevations.

- A pattern change later in the week will lead to cooler temperatures and increasing rain chances to the eastern half of Arizona.

SHORT TERM /Today through Tuesday/

Negative height anomalies in the form of a cutoff low have migrated off the central/southern Baja peninsula in the final vestiges of western Conus Rex blocking. For much of Arizona, subsident ridging with H5 heights near 580dm have folded north of the cutoff with H8 temperatures near +15C and H7 readings above 0C. This pattern configuration will hold nearly steady over the next 36 hours before the relaxation of hemispheric blocking allows longwave Pacific troughing to propagate eastward ejecting the aforementioned cutoff low into the southern plains. As a result, forecast confidence is excellent with respect to temperatures reaching around 15F above normal while approaching daily records today and Monday. The incoming trough Tuesday will force H5 heights closer to a 570-574dm range relegating temperatures back towards a 10F above normal anomaly. Regardless, with dry conditions being maintained over the CWA, widespread minor HeatRisk will be common across lower elevation locations during daytime hours.

LONG TERM /Wednesday through Sunday/

Ensembles continue to be in good agreement in the next troughing feature diving down the West Coast and remaining in the eastern Pacific until late in the week. This feature will bring an increase of high clouds with the addition of cooler temperatures as heights aloft will begin to lower in response. This will lead to afternoon high temperatures in the lower to mid 70s mid to late next week in the lower desert areas (still above normal for this time of year). Though models are not in great agreement with the PVA and moisture associated with this trough, some of the deterministic guidance suggest very limited short-lived rain chances mainly in the eastern portion of the region Friday afternoon, while others suggest more widespread light showers later Friday evening into early Saturday morning. Continued monitoring of how this system will progress later in the week will be needed. If you were excited about seeing precipitation, this system will not be the last hope for precipitation chances as another stronger and better positioned trough looks to be trailing behind. This could lead to more widespread precipitation chances across the Desert SW for the following week, but with this potential system being over a week out, it is difficult to put too much weight into it at this time.

AVIATION

Updated at 0500Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns under mostly clear skies can be expected throughout the TAF period. The overall wind pattern will exhibit light and diurnal tendencies with extended periods of variable to calm conditions. Winds speeds at all terminals will generally be aob 8 kt.

FIRE WEATHER

Well above normal temperatures and dry conditions will continue early this week. Afternoon MinRHs will range from 15-25% through Monday with overnight recoveries generally in a 35-65% range. Winds will remain light, generally below 15 mph through Monday, with a northerly fetch. By the middle of the week, a pattern change is expected which will help cool temperatures several degrees (though remaining above normal), increase MinRHs to 20-30%, and bring occasionally breezy conditions. Late in the week, a weather system will pass through the region providing 15-30% chances for wetting rain over higher terrain areas of the eastern districts.

PSR WATCHES/WARNINGS/ADVISORIES

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