Marine Weather and Tide Forecast for San Luis, AZ

KEY MESSAGES

- Major waterways such as the Salt and Gila Rivers will continue to experience elevated flows through at least the weekend due to dam releases.

- With the exception of a slight chances of showers and thunderstorms over parts of south-central and eastern Arizona this afternoon, dry weather will be common through at least the middle of next week.

- Temperatures will warm toward near and slightly above normal levels for the weekend and into next week.



SHORT TERM /Today through Sunday/
A cut-off low, currently spinning over Arizona and northern Mexico will be the focal point for the most appreciable weather changes observed since the beginning of this week. This feature, along with orographic influences, have already set off some light shower activity this morning over eastern Arizona, but rain chances for this area will extend into this afternoon and evening, with perhaps the lower deserts even seeing a stray shower or two.
Available moisture is not overly impressive, with PWATs around 0.5-0.7" (though this is still 150-200% of normal for this time of year) so most activity during this timeframe, much like the morning, should be fairly light. However, boundary-level mixing ratios are currently around 6-7 g/kg, which, combined with day- time heating, should be sufficient enough to generate at least some modest MLCAPE around 250-500 J/kg, enough to promote some isolated thunderstorms that could yield some higher rainfall rates. As for the above-mentioned lower desert rainfall, as the cold-core dives further south, it will help to pull moisture back toward south-central Arizona which could yield some sprinkles or light showers over areas such as the Phoenix metro, but chances are only around 10-20%. Accumulations will generally be anywhere from a few hundredths to around a tenth of an inch, with some locally higher totals under any heavier shower/storms that can develop.

Higher momentum northerly flow aloft over the lower Colorado River Valley and SE California, a product of the interaction between our regional low and eastern Pacific ridging, will result in some breezy conditions this afternoon and into Saturday morning for those above-listed areas. Gusts 20-30 mph will be common for lower elevation locations while ridgetops can expect occasionally higher gusts. As the high shifts further east as we transition into the weekend, surface pressure rises will help generate some marginal, but seasonally common, nocturnal/morning breeziness for portions of south-central Arizona. Readings 15-25 mph appear to be the most likely outcome with typical locally higher gusts around prominent terrain features.

After another afternoon with temperatures near or just below seasonal norms today, the aforementioned Pacific anti-cyclone will provide us a bit of warming for Saturday and Sunday. Forecasted afternoon highs for this timeframe have ticked up a degree or two over the past few forecast periods and now range generally in the upper 70s to mid 80s for the lower elevations, with mid 60s to mid 70s being common for higher terrain areas. These will likely be the first widespread above-normal values we see so far this November, but by only exceeding seasonal levels by about 3-5 degrees, the weekend should be quite pleasant regionwide.

LONG TERM /Monday through Thursday/
With northern stream jet energy retreating towards the Canadian border under broad ridging, several weak low amplitude features will align in the southern stream over northern Mexico during the first half of the week before large scale hemispheric pattern amplification becomes a dominating feature. Predominant anti- cyclonic flow will continue to promote surface pressure rises over the intermountain West and dry N/NE boundary layer flow. The vast majority of ensemble membership keeps any notable shortwave ascent removed from the CWA, and confidence is very good that dry conditions will prevail through at least the middle of the week.
With H5 heights remaining nearly constant in a 580-584dm range, forecast numerical spread is rather narrow indicating very good confidence in a persistence type forecast and readings very near climatology. Ensemble spread grows markedly towards the end of next week as pronounced northern stream pattern amplification driven largely by an unusual early season sudden stratospheric warming (SSW) event unfolds. The perturbation of the polar vortex should cause poleward ridge retrogression while deep negative height anomalies descend equatorward into the NE Conus and Pacific NW. While operational models are consistent in focusing strong jet energy and Pacific moisture towards northern California with inconsequential shortwave energy into the Southwest, there is a non- trivial amount of NAEFS members suggesting much deeper, intense troughing moving into the local area next weekend. Given this amplification phase, continued wide ensemble spread and potentially large variations in operational models yielding low forecast confidence should be expected into next week.

AVIATION
Updated at 0515Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: Winds will exhibit a E/NE direction through the entire TAF period with speeds generally aob 10 kt through the period. Some occasional gusts in the upper teens are possible tomorrow afternoon. FEW-SCT clouds aoa 7-8 kft will continue through tomorrow afternoon before skies become clear tomorrow evening.

Southeast California/Southwest Arizona including KIPL and KBLH: Winds will exhibit a N/NW component at both TAF sites through the period. Wind speeds at KIPL will be aob 10 kt and wind speeds at KBLH will be aob 13 kt through the period. Skies will remain clear.

FIRE WEATHER
A few isolated showers or thunderstorms may impact higher terrain areas north and east of Phoenix today, however wetting rainfall chances are minimal. Otherwise, dry conditions will prevail across the region through at least the middle of next week. Minimum afternoon humidity levels will largely fall into a 20-30% range in western districts and 30-50% in eastern districts. This will follow fair to good overnight recovery in western districts and good to excellent levels in eastern districts. Northerly winds gusts 20-30 mph will be common in western districts this afternoon through Saturday, while a period of enhanced morning easterly winds will develop over Arizona early next week. Outside of these time frames, wind speeds will be light with limited gustiness.

PSR WATCHES/WARNINGS/ADVISORIES
AZ...None.
CA...None.