30-Day Weather Outlook for July 1, 2024 to July 31, 2024

Jul 01, 2024

BASIC PATTERN

Large Scale Pattern

The focus of lingering upper lows continues west of the Pacific Northwest, and troughing at 140-150W. High pressure aloft develops at times across central California by July 4
Our IVTinitô analysis shows the calculated estimate of one day (Day0 Total Integrated Vapor Transport (TIVT24), based on the sea surface temperature anomaly pattern from the coast out to 180W.
This is calculated by Fox Weather LLCís CyclogenIVT AI application each day. It shows for us the potential areas for development of troughs and rains upstream from California and the West Coast. Physical units of TIVT are comparable to CW3Eís 24 hour TIVT.
Troughing occurs 1-3 July. Upper high pressure and hot conditions develop 4 July onward to 8th. Weak dry troughing occurs 9-10, mostly focused on N and NW California, while SOCAL remains under strong upper high pressure and hot conditions. More troughing occurs about 15 July with a chance for showers or light rain/drizzle at the North Coast Humboldt County north.
For forestry and upcoming Fire Season 2024 in NORCAL and Sierras. it is becoming very dry, with onset of occasional overnight gusty wind events in mountains and NE Plateau, related to troughs coming into the Pacific Northwest and hot upper high pressure developing in most of central and S California including the Sierras.
Tropical cyclones are becoming a regular feature across S Mexico and off to SW of Baja. The strongest cyclone (hurricane strength) appears to develop about 10-11 July to SW of Baja tip and heads WNW-ward.

FORECASTS FOR CALIFORNIA

Forecast for Northern California
NORCAL Precipitation: Jul 16-17
NORCAL Hot-Dry Periods: Jul 2-9, 12-14 and 22-24
NORCAL Cool and Breezy Periods: Jul 16-17, 20-21 and 25-27.

North Sierra Precipitation Jul 15-17
Central Sierra Precipitation Jul 15-16.

Forecast for Central California
Central Calif Precipitation: Dry with rain unlikely
Central Calif Warm/Hot Periods: Jul 2-10, 13-14 and 22-24
Central Calif Cool Periods: Jul 17, 20-21 and 26-27

Forecast for Southern California

SOCAL RAINS: Jul 21 and 25 (east deserts)
SOCAL Warm or hot-dry Periods: Jul 2-10, 13-20 and 23-24
SOCAL Cool Periods: Jul 21 and 25

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The listings of dates normally included for hot and cold spells, and precipitation are approximate. They are based on GFS and our CFSDaily and CFSDailyAI products; and present expected trends in precipitation and temperature (FoxCFSDailyAI) to 5km. Our AI system gives some consideration to terrain and coastal influence. Although we consider the CFSv2 one of the better ways to represent basic weather in the sub-monthly time scale, performance of the CFSDaily. CFSv2 daily products during storm seasons has been especially inconsistent and difficult to apply to the useful criterion needed by cropland agriculture, and viticulture beyond the 15ñday GFS.

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Looking Ahead — Longer Range Outlook for June

Southern California Deserts Outlook

Troughing Dates - Weak trof N Jun 30-July 2

Upper high pressure will become more dominant in July and August due to usual tropical cyclone activity off southern Baja and SW Mexico.

For July 30 - August 30
N and Central California and Sierras

Above average temperature overall, with recurrent very hot spells during August. Rainfall will recover to near or slightly below average. For Southern CaliforniaÖ Away from the coastal influence area, we look for above average temperature overall, with a transition to the usual recurrent hot spells during August. Rainfall will recover to near or slightly below average with a few of the usual mountain/desert TSTMS.

Monsoonal Conditions
Tropical cyclones have begun for the ocean area south of Mexico. Monsoonal moisture and thunderstorm conditions appear to be starting for the mountains of western Mexico.

Looking Farther Ahead
California temperatures appear to return closer to average during mid September onward and through October. It continues drier than average in California through September and into early to mid October.

(Terms and Definitions Used In This Weather Outlook)