Rain Now Expected on Wednesday as Storm Weakens

Satellite image of Hurricane Rosa on September 30, 2018 (Photo: National Weather Service)

Updated Weather Advisory
The National Weather Service is now indicating that the storm that was predicted for Tuesday has weakened and will now arrive on Wednesday. No evacuations from this storm are necessary. The Santa Barbara County Office of Emergency Management and cooperating emergency response agencies will continue to monitor the weather system for changes and will alert the public if the storm becomes a threat for debris flows. Unless the situation changes, no further updates will be issued for this storm. Below is the Spot Weather Forecast:
 
Spot Forecast for SBA South Coast Precipitation Forecast…SBA County OEM National Weather Service Los Angeles/Oxnard CA
137 PM PDT Mon Oct 1 2018
 
Forecast is based on forecast start time of 1400 PDT on October 02.  If conditions become unrepresentative…contact the National Weather Service.
 
.DISCUSSION…Low pressure west of California will approach the southwest coast late Tuesday, then move overhead on Wednesday. This system will continue to weaken as it moves toward land with the heaviest precipitation remaining over the ocean Tuesday afternoon and night. Rain is likely to move onshore on Wednesday with most areas receiving light to briefly moderate rainfall through Wednesday evening. Rainfall totals for the Thomas Fire area through Wednesday is 0.25-0.40 inch for coastal areas and 0.40-0.75 inch for the foothills and mountains of the Santa Ynez Range.

There is a slight chance of thunderstorms Wednesday afternoon, but the risk of rain rates exceeding 0.50 inch/hour is extremely low at this time. [USGS thresholds this season begin at 0.80 inch/hour]. 
 
There is still uncertainty with timing and rainfall amounts with this first rain system of the season. Most importantly we will have a better idea on rain rates on Tuesday when high resolution models
capture this event. 
 
Overall the main impacts in Santa Barbara County will be minimal with just the typical slick roadways and clogged drains that can create traffic issues. 
 
TUESDAY
Sky/weather………Increasing clouds. 
Max temperature…..70-74. 
Wind (20 ft)…….. 
Slope/valley…….Southwest winds 5 to 10 mph early then becoming southwest 8 to 15 mph with gusts to 20 mph. 
Pcpn amount………0.00 inches. 
 
TUESDAY NIGHT
 
Sky/weather………Mostly cloudy. 60 percent chance of rain showers well after midnight. 
Min temperature…..Around 56-60. 
Wind (20 ft)…….. 
Slope/valley…….Southeast winds 5 to 10 mph. 
Pcpn amount………0.15-0.25 inches. 
Rainfall intensity..up to 0.15 inch/hour.
 
WEDNESDAY
 
Sky/weather………Rain showers likely (70 percent chance) through the day. Slight chance of thunderstorms in the afternoon. 
Max temperature…..66-70. 
Wind (20 ft)……..

Slope/valley…….Southeast winds 5 to 10 mph. Locally gusty winds to 20 mph in the afternoon and near any thunderstorms.  

Pcpn amount………0.25-0.50 inches. 
Rainfall intensity..up to 0.33 inch/hour. Possibly 0.50 inch/hour in thunderstorms.

The National Weather Service (NWS), the Santa Barbara County Office of Emergency Management, and cooperating emergency response agencies are all closely monitoring the weather system which is forecasted to arrive in the Santa Barbara area Tuesday afternoon 10/2/18.

At this time the NWS does not expect the system to reach rain intensity thresholds which can produce debris flows from the recent burn areas. No evacuation orders or warnings are planned at this time. Conditions can change so please continue to monitor local news and weather. This office will provide another update tomorrow afternoon.

Go to www.readysbc.org for updates. See below for the latest NWS spot weather forecast for the SB South Coast/mountains.

The first storm of the season is expected to impact the Santa Barbara south coast Tuesday into Wednesday. While there is increasing confidence that rain will occur across the south coast sometime in this time period, there is still considerable uncertainty in the rainfall amounts, timing, and intensities. There is a 20 percent chance of thunderstorms across the south coast sometime between Tuesday afternoon and Wednesday afternoon which could be capable of producing brief heavy downpours.

As a result, there is a low probability of reaching USGS thresholds (0.80 inches in 60 minutes, 0.60 inches in 30 minutes, and 0.40 inches in 15 minutes) for the burn areas in the Tuesday afternoon through Wednesday afternoon time period. Storm totals are generally expected to range between 0.50 and 1.50 inches across the South coast, but local amounts up to 2.00 inches will be possible across south facing slopes and near thunderstorms.

TUESDAY

TUESDAY NIGHT

WEDNESDAY

Sky/weather…………Mostly cloudy. 70 percent chance of showers. 20 percent chance of thunderstorms.
Max temperature……..66-70.
Wind (20 ft)………..South to southeast 8 to 15 mph with gusts to 20 mph.
Rainfall intensities…Low probability of reaching USGS thresholds.