textproduct: NWS Phoenix

UPDATE

Updated Aviation

KEY MESSAGES

- Dry conditions with above normal temperatures and mostly clear skies will prevail through the middle of next week. - Periods of breezy winds will affect the Lower Colorado River Valley and higher terrain areas of south-central Arizona today, Friday, then again during the middle and end of next week.

SHORT TERM /TODAY THROUGH FRIDAY/

Skies are steadily clearing west to east early this afternoon with high pressure ridging developing along the West Coast. This ridge will continue to nudge eastward into the Interior West through the end of the week and through this weekend. This high pressure will continue to result in above normal temperatures across the region, with a slow warming trend into the weekend. For today and Friday, lower desert high temperatures are expected to top out in the middle to upper 70s, around 5-8 degrees above normal for the end of January. Morning low temperatures will remain around seasonal levels, which is chilly for most desert folk. With clear skies tonight, lows will be a degree or two cooler than they were this morning, with most lower desert locations in the 40s.

In addition to the temperatures, there are some breezy spots today, in response to 1032mb+ surface high pressure over the Great Basin. The breeziest spot is along the Lower CO River where winds have been gusting up to 20-30 mph from the north. The daytime breeziness will continue through at least Friday, with the gradient pivoting to favor more of a northeasterly wind. The northerly to northeasterly winds will also bring drier air, with afternoon dew point temperatures falling into the teens, and should bring some downslope warming into the lower deserts.

LONG TERM /SATURDAY THROUGH NEXT FRIDAY/

Higher amplitude ridging is heavily favored to move eastward from off the West Coast by Saturday with H5 heights over our region rising to between 579-582dm, or well into the 90th percentile of climatology. The higher heights, continued dry conditions, and plenty of sunshine are expected to push daytime highs to around 80 degrees for a good portion of the lower deserts this weekend. Guidance also shows a weak cut-off low developing well west of Baja on Friday before drifting eastward over the weekend. The most likely track of this feature keeps it to our south passing across central Baja on Sunday as it becomes an open wave. Our region should see a slight uptick in moisture over the weekend and some higher level clouds on Sunday, but little if anything will come from this cut-off low.

For at least the first half of next week, our weather will remain quiet with dry conditions persisting. For Monday and Tuesday, heights aloft are expected to lower due to the lingering dying cut- off low as well as a passing shortwave trough well to our northeast. We are also likely to see a decent amount of high clouds early next week which combined with the lowering heights should knock a couple of degrees off of daytime highs. The latest NBM shows lower desert highs mostly in a 76-80 degree range for Monday and Tuesday.

Ensembles then show a Rex block developing Tuesday into Wednesday with the core of the ridge setting up over the Pacific Northwest into the Great Basin and another cut-off low developing somewhere to our southwest. Our region should continue to be dominated by the upper level ridge through at least Thursday and potentially longer depending on what happens with the cut-off low. Temperatures will at least remain above normal during the latter half of next week, but they may start to trail off by next weekend if the cut-off low shifts into our region. There is too much uncertainty at this point to know if and when the cut-off low may affect our region. Ensembles do show some small precip chances by around Friday or into next weekend, but so far only 5-10% of the members show QPF for Phoenix. There will also likely be some more northerly to northeasterly breeziness mid to late next week with surface high pressure redeveloping and strengthening to the north under the ridge.

AVIATION

Updated at 0510Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No major weather issues will exist through Friday night under clear skies. East winds should prevail through mid afternoon, however model evidence shows a brief period of a light SW wind around sunrise at KPHX before reverting back to easterly. Confidence is good that the typical west switch Friday afternoon will likely occur towards late afternoon before switching back to east mid evening.

Southeast California/Southwest Arizona including KIPL and KBLH: Under clear skies, the primary weather issue Friday afternoon will be locally gusty north winds. Gusts around 20 kts at KBLH should materialize again early Friday afternoon before relaxing after sunset. Similar to the past 24 hours, wind directions will shift between northerly and westerly at KIPL with little to no gustiness.

FIRE WEATHER

Dry weather conditions will prevail through the next week, with MinRH values in the 10-20% range most afternoons. There will be a subtle moisture increase late this weekend into Monday, but MinRH values only increase to 20-25% at best. Overnight recoveries will remain poor to fair with humidities mostly between 30-55%. Some breezy winds are ongoing this afternoon, focused along the Lower CO River Valley, with gusts up to 20-30 mph. Another round of breeziness is expected again tomorrow afternoon for the same western districts and some parts of south-central AZ. There may also be lingering easterly breeziness across south-central AZ Saturday and Sunday. The weather pattern will again support breezy daytime conditions mid to late next week. Temperatures will continue to warm several degrees above normal each day, with lower desert highs peaking near 80 degrees this weekend.

PSR WATCHES/WARNINGS/ADVISORIES

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