Sunrise 6:09 AM   Sunset 8:09 PM Moonrise 2:54 AM   Moonset 2:13 PM

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PZZ455 Cape Mendocino To Pt Arena Out 10 Nm- 310 Am Pdt Fri May 3 2024
Today - NW winds 5 to 10 kt. Waves nw 5 ft at 8 seconds. Tonight - SE winds 5 to 10 kt - .becoming W 10 to 20 kt. Waves nw 4 ft at 7 seconds. Patchy dense fog. Rain.Sat - NW winds 10 to 15 kt. Waves W 5 ft at 7 seconds. Isolated showers and tstms. Sat night - NW winds 5 to 15 kt. Waves W 7 ft at 9 seconds. Sun - NW winds 5 to 10 kt. Waves W 6 ft at 9 seconds - .and nw 3 ft at 15 seconds. Mon - NW winds 5 to 15 kt. Waves nw 4 ft at 5 seconds - .and nw 5 ft at 12 seconds. Tue - N winds 15 to 25 kt. Waves nw 9 ft at 8 seconds - .and nw 7 ft at 16 seconds.

PZZ400 310 Am Pdt Fri May 3 2024
Synopsis for northern california waters - Lighter winds and lower seas are forecast for today. Southerly winds will increase ahead of a cold front this evening, followed by a rapid shift to westerly after frontal passage late tonight into early Saturday morning. Gusty and sudden westerly wind gusts to 25 kt are possible on Saturday.

FXUS66 KEKA 031251 AFDEKA

AREA FORECAST DISCUSSION National Weather Service Eureka CA 551 AM PDT Fri May 3 2024

SYNOPSIS
A cold front will move across the area this evening through early Saturday morning bringing a period of heavy rain.
Brief heavy wet snow is also expected above 2500 feet early Saturday morning. Colder air will settle over the area for the remainder of the weekend with frost and freezing temperatures expected for the interior valleys during early morning hours.

DISCUSSION
Prefrontal light rain is expected to begin over Del Norte County late this afternoon. Heavy rain will develop this evening for Del Norte and northern Humboldt as a surface cold front moves southward by midnight or shortly after. Heavy rain rates >0.30in/hr are probable (>70% chance). Chance for hourly rates >0.50in/hr are 10-20% for the interior mountains Del Norte and Humboldt, except for the King Range where it is 40%. These heavy rates (>0.50in/hr) per the HRRR are not expected to sustain over a large area (an entire basin) for more than hour or two and thus will hold off on hoisting a flood watch. Minor nuisance flooding of low-lying areas with poor drainage and ponding water on roads are certainly possible with these heavy rates. It is quite anomalous for early May and will continue to highlight the heavy rain in a weather story graphic and social media post. Flows on the rivers are low and April was not exactly wet with above normal precip, so soils are not saturated as earlier this winter. There will be run-off concerns and advisories may be necessary once the heavy rain commences by late this evening.

The cold front will move SE by early Saturday and southern Mendocino and southern Lake Counties will also get a good soaking of rain, 0.50-0.75in over 6-12 hours, mostly Saturday morning. Threat of widespread heavy rain will diminish rapidly by midday Saturday after the brief influx of moisture shifts southward and an unseasonably cold airmass settles over the area. Looking at the HRRR, snow levels are forecast to rapidly fall early Saturday with probabilities >70% for hourly snow rates > 1in/hr. This warrants at least a winter weather advisory for elevations above 2500 feet.
Greatest uncertainty is with snow levels. Levels could vary to as low 2000 feet to as high as 3500 feet. Leaned toward lower snow levels, 2500 ft, due heavy precip rates driving the freezing levels lower. Impacts over the major highway passes will be offset the high May sun angle and relatively warm road surface.
Reduced visibilities from heavy snow and slick roads will have impacts and a winter weather advisory has been hoisted til 11 AM Saturday.

Shower activity will continue during the day on Saturday as the cold core aloft moves overhead and onshore westerlies bring open cellular shallow convection onto the coast. Not all that confident in the potential for low topped thunderstorms with surface temperatures cooling down drastically in the interior and 850mb temps dropping to -3C. High temps for the warmest valleys will struggle to reach 60F. After the precip winds down or diminishing subfreezing temperatures will be primary concern for the interior Sunday morning. It is certain (100%) for the mountains. Valleys will most likely freeze too (>70% chance), mostly in Trinity County. Spreads are much wider with probabilities from 30% to 70% for valleys in Del Norte, Humboldt, Mendocino and Lake. Frost or mid 30's are much more certain, even for coastal areas. Fog and low clouds will probably form and hinder the longwave cooling in some valleys, especially after 1 to 3 inches of rain.

Another shortwave trough in NW flow will probably generate more showers Monday (highest chances Del Norte and northern Humboldt).
This trough will not be as cold and moisture will be limited.
Surface northerlies will begin to strengthen after passage of this shortwave trough and dry conditions are most likely into mid week (>80% chance). Majority of the 500mb ensemble cluster means (>80%) leads to more confidence in dry weather with slow warming of daytime temperatures. The one caveat to the "warming" will be potential for freezing early morning temps in the interior valleys under clearer skies and calm or light winds, assuming absolutely no fog and low clouds. Also, the strength of E-NE winds will factor into "how warm" and the eventual return of coastal stratus.
High temps in the low 90's for warmest valley are not completely out of the realm of possibilities either, increasing to 20-40% on Friday. Interior valley high temps in the 80's are much more probable (>60%) by Friday. DB

AVIATION
VFR prevailed at all terminals this morning. Nighttime fog product showed extensive low clouds and fog in the interior valleys. The LIFR conditions (1/4SM VV002 at FOT for example) will most likely not have long duration impacts at any of the terminals this morning. It may spill out from the valleys around daybreak and get close to KACV resulting in brief LIFR. Otherwise, VFR is forecast to prevail today as multi-layered clouds with an approaching front increase through the day. Conditions are forecast to deteriorate to IFR in moderate to heavy rain this evening at KCEC and KACV. IFR conditions will take longer to envelope UKI where LLWS should return with frontal passage by 12Z Sat. DB

MARINE
Northerly winds have diminished in response to an approaching front. Southerlies are expected to develop this morning and slowly increase through the day today ahead of the cold front. Southerly gusts up to 30 kts are forecast with the passage of the front, particularly in the northern inners this evening, then sharply shift to west behind it's passage. Gusts up to 25 kts are expected with passing convective showers into Saturday morning, slowly becoming restricted to the southern outers by Saturday afternoon. Winds weaken Saturday night and turn westerly Sunday. Another weak frontal passage may pass early next week, then more robust northerlies are possible by midweek. Seas remain low and locally generated through this weekend, and a series of NW swells are expected to fill in early next week.
DB/TDJ

EKA WATCHES/WARNINGS/ADVISORIES
CA...
Winter Weather Advisory from 4 AM to 11 AM PDT Saturday for CAZ102-105>108-111.

Frost Advisory until 8 AM PDT this morning for CAZ107-108.

NORTHWEST CALIFORNIA COASTAL WATERS...
Small Craft Advisory from 9 PM this evening to 3 AM PDT Saturday for PZZ450.

Small Craft Advisory from 9 PM this evening to 9 AM PDT Saturday for PZZ470.

Small Craft Advisory from 3 AM to 9 PM PDT Saturday for PZZ475.

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Mendocino
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Fri -- 01:52 AM PDT     2.08 feet Low Tide
Fri -- 03:54 AM PDT     Moonrise
Fri -- 06:13 AM PDT     Sunrise
Fri -- 07:20 AM PDT     4.66 feet High Tide
Fri -- 01:54 PM PDT     -0.00 feet Low Tide
Fri -- 03:13 PM PDT     Moonset
Fri -- 08:11 PM PDT     Sunset
Fri -- 08:42 PM PDT     5.25 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Mendocino, Mendocino Bay, California, Tide feet

Point Cabrillo
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Fri -- 02:51 AM PDT     0.00 knots Slack
Fri -- 03:54 AM PDT     Moonrise
Fri -- 05:33 AM PDT     0.71 knots Max Flood
Fri -- 06:13 AM PDT     Sunrise
Fri -- 08:19 AM PDT     -0.00 knots Slack
Fri -- 11:22 AM PDT     -1.13 knots Max Ebb
Fri -- 03:05 PM PDT     0.00 knots Slack
Fri -- 03:13 PM PDT     Moonset
Fri -- 06:11 PM PDT     1.08 knots Max Flood
Fri -- 08:11 PM PDT     Sunset
Fri -- 09:20 PM PDT     -0.00 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION

Point Cabrillo, California Current, knots

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