Weather Alert 7/18-7/21 | High Sierra Topix  

Weather Alert 7/18-7/21

Discussion related to Sierra Nevada current and forecast conditions, as well as general precautions and safety information. Trail conditions, fire/smoke reports, mosquito reports, weather and snow conditions, stream crossing information, and more.
User avatar

Weather Alert 7/18-7/21

Postby maverick » Mon Jul 13, 2015 3:45 pm

Models are showing two scenarios, one having the hurricanes energy missing us, the other having an impact on the southern Sierra, and mixing with the monsoonal flow from the southwest. Please keep any eye on this as we get closer towards the weekend, if the second scenario plays out, it could be a really wet and electric weekend, and possibly beyond in the Sierra.

.DISCUSSION...
SATELLITE LOOPS SHOW MAINLY CLEAR SKIES ACROSS THE CENTRAL
CALIFORNIA INTERIOR. TEMPERATURES AT MIDDAY WERE RUNNING A COUPLE OF
DEGREES WARMER THAN 24 HOURS AGO...IN THE LOWER TO MID 80S IN THE
SAN JOAQUIN VALLEY...AND HIGH TEMPERATURES IN THE CENTRAL AND
SOUTHERN SAN JOAQUIN VALLEY ARE ON TRACK TO REACH THE MID 90S.

AN UPPER-LEVEL TROUGH WILL REMAIN OVER CALIFORNIA THROUGH MIDWEEK...
KEEPING SKIES CLEAR AND TEMPERATURES SLIGHTLY BELOW NORMAL IN A DRY
SOUTHWESTERLY FLOW ALOFT. FOR THE LATTER HALF OF THE WEEK THE TROUGH
IS FORECAST TO WEAKEN AND HIGH TEMPERATURES IN THE CENTRAL AND
SOUTHERN SAN JOAQUIN VALLEY WILL WARM TO AROUND 100.

THE FORECAST FOR THE COMING WEEKEND HAS A GREATER DEGREE OF
UNCERTAINTY TODAY...AS THE ECMWF AND GFS NOW HAVE DIVERGENT
SOLUTIONS FOR HURRICANE DOLORES. AT 20Z /1300 PDT/ THIS AFTERNOON...
DOLORES WAS WEST OF THE CENTRAL MEXICAN COAST NEAR 17.2 N/ 106.3 W.
DOLORES HAD SUSTAINED WINDS OF 65 KTS WITH GUSTS TO 75 KTS. THE
HURRICANE WAS MOVING WEST-NORTHWEST AT 8 KTS.

THE 12Z GFS TRACKS DOLORES NORTHWESTWARD THROUGH WEDNESDAY...THEN
TURNS THE STORM WESTWARD TO 20N/120W BY SATURDAY EVENING. THE
HURRICANE IS THEN FORECAST TO TRACK NORTHWEST SUNDAY AND MONDAY
BEFORE GETTING CAUGHT IN THE CIRCULATION AROUND AN UPPER-LEVEL RIDGE
CENTERED OVER THE DESERT SOUTHWEST TUESDAY OF NEXT WEEK. IF THIS
SOLUTION IS CORRECT...MOISTURE FROM DOLORES WOULD STAY WELL AWAY
FROM CALIFORNIA THIS WEEKEND AND CONDITIONS FOR INTERIOR CENTRAL
CALIFORNIA WOULD BE WARM AND MOSTLY DRY ALTHOUGH THE GFS DOES BRING
A MONSOONAL INFLUX INTO THE KERN COUNTY MOUNTAINS AND DESERT
SATURDAY NIGHT AND SUNDAY FOR INCREASED CLOUDS AND POSSIBLE SHOWERS
AND THUNDERSTORMS.

THE 00Z ECMWF TRACKS DOLORES NORTHWEST TO 24N/120W BY 00Z SUNDAY
/1700 PDT SATURDAY/...THEN TURNS THE STORM NORTHWARD AND WEAKENS IT
AS IT BECOMES ENTRAINED IN THE FLOW AROUND THE RIDGE OVER THE
SOUTHERN UNITED STATES. THE ECMWF HAS MOISTURE FROM DOLORES PUSHING
INTO SOUTHERN CALIFORNIA BEGINNING SATURDAY AS WELL AS THE MONSOONAL
SURGE FROM THE SOUTHEAST. THE ECMWF SOLUTION WOULD BRING A BETTER
CHANCE FOR SHOWERS AND THUNDERSTORMS TO MOST...IF NOT ALL...OF THE
WFO HANFORD WARNING/ FORECAST AREA FOR THE WEEKEND.

BECAUSE OF THE DIFFERENCES BETWEEN THE ECMWF AND THE GFS...THE
FORECAST IS A COMPROMISE BETWEEN THE SOLUTIONS. HAVE GONE WITH
SLIGHT CHANCE POPS FOR THE KERN COUNTY MOUNTAINS AND DESERT AND THE
TULARE COUNTY MOUNTAINS SATURDAY AFTERNOON/EVENING WITH SLIGHT
CHANCE POPS FOR THUNDERSTORMS SPREADING ACROSS THE ENTIRE WFO HANFORD
WARNING/FORECAST AREA SATURDAY NIGHT THROUGH NEXT MONDAY...EXCEPT
FOR CHANCE POPS OVER THE HIGHER TERRAIN OF THE SOUTHERN SIERRA
NEVADA...INCLUDING THE PIUTES SATURDAY NIGHT THROUGH SUNDAY NIGHT
AND CONTINUING NORTH OF KERN COUNTY MONDAY MORNING.
HST= Wilderness Adventurer who knows no bounds, except for their own imagination.

Have a safer backcountry experience by using the HST ReConn Form 2.0, named after Larry Conn, a HST member: http://reconn.org



User avatar
maverick
Forums Moderator
Forums Moderator
 
Posts: 8028
Joined: Thu Apr 06, 2006 5:54 pm
Experience: Level 4 Explorer

User avatar

Re: Weather Alert 7/18-7/19

Postby Hobbes » Mon Jul 13, 2015 4:32 pm

I was thinking of posting this earlier, but figured I could wait until you put up a more official weather warning:

Saturday the 18th into Sunday the 19th could see very significantly sized surf from Dolores as this system makes its way to SoCal, potentially making landfall on the US/Mexico border in San Diego around that time. Wave energy could be in the overhead range Saturday the 8th, with swell angled from a slightly better 165°. Sunday the 19th could then see wave energy reach DOH at south facing breaks with swell angled from 170-180°.

Conditions, however, are highly questionable by the weekend. Although the current course for Dolores only goes out 5 days on the NHC models, longer range models show Dolores sitting just a couple hundred miles off the SoCal coast this weekend...and then hitting SoCal Saturday afternoon. Nearly all models I'm looking at this morning (FNMOC, GFS, NCEP) agree on this — there is only one outlier right now, the CMC-GDPS, European model, that shows anything different, and even that just delays the storm's arrival until Sunday into Monday, and staying just a tad more off the coast.

Most all weather models show Dolores either making landfall in San Diego (near the Mexican border) or fizzling out no more than 200-300 miles off LA. Either way, rain becomes extremely likely. Currently, it looks like SD could see light rain early Saturday morning, and then all of SoCal seeing heavy rain by Saturday afternoon into Sunday morning. Winds could also become quite strong...see below....

Winds at 8:00 AM were light and variable. Afternoon onshores should reach 10-15 mph. No major change is expected through Friday. Saturday is when winds become questionable from Dolores. If Dolores takes the path most weather models show today, then winds could reach 35 mph off SD early Saturday morning, and about 20-30 mph from VC south through OC later in the morning on Saturday. Also, winds may be strongly offshore on Dolores's north end (as it spins counter-clockwise). So, LA and VC could see offshore winds Saturday morning, but not long before SE winds come ashore. Either way, it's too early to call Dolores today...more details in my next report.


http://forecasts.surfingmagazine.com/#p ... one_Sat_-1

If this hurricane goes out to sea, then we should expect to see some normal moonsonal flow. However, it it tracks up into San Diego and into the Mojave, then the amount of rain that could hit the Sierra & Owens valley could be quite significant. The huge ravine in the Shepherd trail was created by a flash flood 2 years ago in 7/2013.

I've been planning on heading up Shepherd to the meet-up on Tues, so besides hoping for some good surf this coming weekend, I'm watching to see what the storm's impact will be.
User avatar
Hobbes
Topix Expert
 
Posts: 678
Joined: Wed Apr 27, 2011 8:09 am
Location: The OC
Experience: N/A

User avatar

Update

Postby maverick » Tue Jul 14, 2015 3:48 pm

NWS:

THE PATTERN BECOMES MORE COMPLICATED IN THE SATURDAY THROUGH
MONDAY PERIOD. DURING THIS TIME WE WILL NEED TO KEEP OUR EYES
FOCUSED ON THE TROPICS. THE MODELS INDICATE THAT MOISTURE FROM
HURRICANE DOLORES WILL INEVITABLY GET ENTRAINED IN THE SOUTHWEST
FLOW ALOFT OVER CA. WHAT REMAINS UNCERTAIN IS HOW FAR NORTH THIS
MOISTURE GETS BY SUNDAY AND MONDAY. A LOT WILL DEPEND ON THE
POSITION OF AN UPPER LEVEL TROUGH IN THE NORTHERN BRANCH OF THE
JET STREAM. THE 12Z GFS BRINGS THIS TROUGH INTO NORTHERN CA THIS
WEEKEND WHICH WOULD THEORETICALLY SHEAR APART AN INFLUX OF
MOISTURE ANY FARTHER NORTH THAN KERN COUNTY. ON THE OTHER HAND...
THE 12Z ECM AND CANADIAN GLOBAL SOLNS KEEP THE DOOR WIDE OPEN TO
THE TROPICS THIS WEEKEND AND BRING TROPICAL MOISTURE INTO NORTHERN
CA AS EARLY AS SUNDAY MORNING. CONSIDERING HOW EASILY MOISTURE FROM
EPAC TROPICAL CYCLONES HAS MADE INROADS INTO CENTRAL CA THIS
YEAR...WE ARE LEANING HEAVILY TOWARD THE EUROPEAN AND CANADIAN
SOLUTIONS WHICH COINCIDENTALLY SIDE WITH THE LATEST ENSEMBLES.
ADDITIONALLY...THE MODELS FORECAST A NORTHWARD SURGE OF HIGH
PRECIPITABLE WATER INTO CENTRAL CA (1.75+ INCHES) IN THE SUNDAY
THROUGH MONDAY PERIODS. ANY UPPER LEVEL ENERGY BROUGHT INTO CENTRAL
CA BY THE TROUGH IN THE NORTHERN BRANCH DURING THIS TIME FRAME COULD
EASILY IGNITE THUNDERSTORM DEVELOPMENT ANYWHERE OVER THE CWA. POPS
WERE INCREASED SLIGHTLY DURING THIS PERIOD ACCORDINGLY AND ARE
CERTAINLY WELL ABOVE CLIMO IN MOST AREAS.

BY NEXT TUESDAY...A SLIGHTLY DRIER AND MORE STABLE AIR MASS
MIGHT SETTLE INTO CENTRAL CA AS THE TROUGH IN THE NORTHERN BRANCH
SHIFTS EASTWARD. HOWEVER...THE 12Z ECM FORECASTS WINDS ALOFT TO
REMAIN RATHER LIGHT...AND SOUTHERLY...SO THERE IS LOW CONFIDENCE
THAT TROPICAL MOISTURE...ONCE HERE...WILL EVER GET SWEPT OUT OF
CENTRAL CA ON DAY 7. WE CURRENTLY CONFINE THUNDERSTORM CHANCES TO
THE SIERRA NEXT TUESDAY BUT IT COULD JUST AS EASILY ENCOMPASS
MORE OF THE CWA IF THE ECM SOLN WINS OUT. WHATEVER THE CASE...OUR
WEATHER WILL DEFINITELY TREND CLOUDIER AND RATHER MUGGY THIS
WEEKEND WITH AN INCREASE IN THUNDERSTORM ACTIVITY...ESPECIALLY
OVER THE HIGHER TERRAIN.
HST= Wilderness Adventurer who knows no bounds, except for their own imagination.

Have a safer backcountry experience by using the HST ReConn Form 2.0, named after Larry Conn, a HST member: http://reconn.org
User avatar
maverick
Forums Moderator
Forums Moderator
 
Posts: 8028
Joined: Thu Apr 06, 2006 5:54 pm
Experience: Level 4 Explorer

User avatar

Weather Update

Postby maverick » Sun Jul 19, 2015 10:09 am

Flash Flood Watch in effect till mid-day Monday.


NWS Hanford:

.SYNOPSIS...
TROPICAL MOISTURE WILL CONTINUE FLOWING INTO THE REGION FROM THE
SOUTH. THERE WILL REMAIN A THREAT OF SHOWERS AND THUNDERSTORMS
TODAY AND CONTINUING INTO EARLY THIS WEEK.

&&

.DISCUSSION...
TROPICAL MOISTURE MOVED INTO INTERIOR CENTRAL CALIFORNIA WITH A
VENGEANCE SATURDAY...TRIGGERING THUNDERSTORMS THAT PRODUCED LOCALLY
HEAVY RAIN. IN JUST 34 MINUTES...FROM 0219-0253Z SUNDAY /1919-1953
PDT SATURDAY EVENING/...FRESNO RECEIVED MORE RAIN /0.34 INCH/ THAN
ITS ENTIRE PREVIOUS WETTEST JULY ON RECORD /0.33 INCH IN 1913/.

THUNDERSTORMS CONTINUED OVERNIGHT IN SAN LUIS OBISPO AND KERN
COUNTIES AS THE WARM...MOIST AIRMASS CONTINUED TO STREAM INTO
CENTRAL CALIFORNIA. THE 06Z NAM-12 HAS TWO MOISTURE SOURCES FEEDING
INTO THE TROPICAL AIRMASS. THE FIRST IS MONSOONAL MOISTURE WRAPPING
AROUND THE UPPER-LEVEL RIDGE OVER THE SOUTHERN UNITED STATES. THIS
MOISTURE IS THE CAUSE OF THE CURRENT THUNDERSTORM ACTIVITY. THE
SECOND PUSH OF TROPICAL MOISTURE IS THE REMNANTS OF FORMER HURRICANE
DOLORES...WHICH THE NAM-12 HAS ARRIVING INTO CENTRAL CALIFORNIA
TONIGHT THROUGH MONDAY AND INTO MONDAY EVENING.

HAVE ALREADY SEEN SOME STATIONS IN THE KERN COUNTY MOUNTAINS
RECEIVING OVER AN INCH OF RAIN...WITH FRAZIER PARK RECORDING OVER 2
INCHES. THERE WERE SOME MUD SLIDES IN THE MOUNTAINS SATURDAY...AND
WITH TROPICAL MOISTURE CONTINUING TO STREAM INTO THE REGION EXPECT
MORE HEAVY RAIN FROM THUNDERSTORMS THE NEXT COUPLE OF DAYS. THE
MOISTURE IS FORECAST TO SPREAD NORTHWARD TODAY...SO HAVE EXPANDED
THE FLASH FLOOD WATCH TO INCLUDE ALL OF THE SOUTHERN SIERRA NEVADA
AS WELL AS THE KERN COUNTY MOUNTAINS AND DESERT.

TUESDAY WILL BE A TRANSITION DAY AS THE MODELS BEGIN DRYING OUT THE
MID LEVELS OF THE ATMOSPHERE. EXPECT THAT ORGANIZED CONVECTION WILL
BE CONFINED TO THE SOUTHERN SIERRA NEVADA.

AN UPPER-LEVEL TROUGH IS FORECAST TO DROP THROUGH THE PACIFIC
NORTHWEST INTO NORTHERN CALIFORNIA WEDNESDAY. THIS WILL BRING A
DRYING NORTHWEST FLOW ALOFT TO CENTRAL CALIFORNIA...ENDING THE
THREAT FOR CONVECTION.

TROUGHINESS IS FORECAST TO CONTINUE OVER CALIFORNIA FOR THE LATTER
HALF OF THE WEEK INTO THE WEEKEND. TEMPERATURES WILL BE A COUPLE OF
DEGREES BELOW NORMAL THROUGH THE FORECAST PERIOD WITH DRY WEATHER
FOR THE EXTENDED FORECAST.
HST= Wilderness Adventurer who knows no bounds, except for their own imagination.

Have a safer backcountry experience by using the HST ReConn Form 2.0, named after Larry Conn, a HST member: http://reconn.org
User avatar
maverick
Forums Moderator
Forums Moderator
 
Posts: 8028
Joined: Thu Apr 06, 2006 5:54 pm
Experience: Level 4 Explorer


Return to Conditions Reports and Information



Who is online

Users browsing this forum: No registered users and 8 guests