Tag: Thunderstorm

Rain For SoCal, Again

Once again we’re right on the 3-hour flash flood line. I expect some flooding. Homes in burn areas will be threatened by mudslides. A few inches of rain probable through this region.

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Helaine saw the hashtag #stormageddon touted on TV a few minutes ago. SoCal is bracing… again. Is there some weird secret competition with the East on weather?

“Yeah… well… rain!”

Actually this storm looks very un-SoCalish. The radar from Vandenberg AFB shows a squall line out front. The HRRR agrees. The squalls remain intact as the line slides down the coast. Embedded thunderstorms are entirely possible.

We’ll have rain most of the day Friday though the bulk falls between 4-7 AM. We’re right on the 3-hour flash flood line, again. I expect some flooding. Homes in burn areas will be threatened by mudslides. A few inches of rain probable through this region.

wind15min_t410m_f0945The heaviest wind comes with the heaviest of the rain. Winds will gust out of the south. The wind map to the left highlights the higher ground where winds will be strongest.

If there’s snow for our two nearby tall peaks it will happen late in the storm. My second winter and no white so far.

Father north, San Francisco proper has gotten 2-4″ of rain with some windward mountainsides getting over 7″.

So far, this is the awful winter everyone was praying for!

Do You Miss Buffalo?

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I was just on the phone with my dad. We talked about the weather a little. He’s in Milwaukee where it’s 29 with a wind chill of 22. My office window thermometer shows 72.

“Bet you’re glad you’re not in Buffalo,” he said.

I am.

766 Auburn Ave Google Maps

I lived here, at 766 Auburn Avenue (Google streetview link) in the third floor apartment. It was a beautiful one bedroom with no insulation and enough water pressure to take a shower if no one in the other two apartments was! During the summer we were woken by squirrel races on the roof.

Those who live in Buffalo do so by choice. Anyone who wanted to leave left a long time ago. There is a survivor spirit among the residents.

It is a really nice, liveable city. Real estate is very reasonable. Summers are magical. Winters are hellish.

Starting in mid-November a thick veil of low clouds descends upon the city. This is the beginning of the process that spawns Lake Effect snow. It’s convection, like bubbles in a pot of boiling water. It will remain mainly cloudy with a handful of exceptions until spring.

This time of year the Great Lakes are warm and the flow through the atmosphere cold. Warm air near the lake’s surface is drawn up, condensing as it cools. Clouds form, often dropping snow.

Lake Effect season begins suddenly. The start is when the potential for big storms is greatest… as we saw this past week. Once Lake Erie freezes the process shuts down.

Lake Ontario doesn’t freeze. Sorry Syracuse.

For a real Lake Effect event, winds must be aligned through the atmosphere often parallel to a lake’s longest dimension.

These storms are VERY localized. The physics involved in Lake Effect snow is very similar to summertime thunderstorm formation. In fact, sometimes thundersnow is part of a Lake Effect storm.

Think “thunderstorm downpour” of snow… except instead of moving on, the storm continues for hours or days relentlessly.

aurora

This graph is from East Aurora, NY. Under land use it’s marked, “Urban.” People live there. That’s over 30″ of snowpack with a water equivalent of 5″.

The edges of Lake Effect storms are well pronounced. You drive out of Lake Effect snow like you drive out of a summer thunderstorm. And these boundaries stay in place as long as the wind doesn’t shift.

No one can cope with this much snow. No one is equipped, even those areas that get as much as 200″ of snow a year!

“Yes, Dad. I’m glad I’m not in Buffalo.” But I don’t regret a day of living there.

Let’s Look At Clouds From Both Sides Now

If it looks like the clouds are boiling, just like a pot of water on the stove, it’s because the dynamics are very similar. Heat is being transferred upward through convection.

NWS EDD

We seldom get the big picture of what’s on the radar by just looking at the sky. Not today. Today is different in SoCal.

The atmosphere is unstable on the the other side of the Santa Ana Mountains, around 30 miles east of me. That’s where the radar (at the top of this entry) shows strong thunderstorms.

What’s striking in the time lapse below are the mid and upper levels of the clouds producing the storms. There are no clouds in the way blocking my view.

If it looks like the clouds are boiling, just like a pot of water on the stove, it’s because the dynamics are very similar. Heat is being transferred upward through convection.

The heavy rain and lightning bolts are out-of-sight behind the mountains. Here, I only see the signs. Everything is moving north and will soon be gone.

Gray And Gloomy

In SoCal people look forward to these gray days as a break from our endless sunshine. An OC native I spoke to yesterday was curious if I missed rain?

Right.

I wanted to say, “You’re nuts.” I held my tongue.

towercam

When I got up this morning (OK–it was afternoon. So shoot me.) the sky was gray. Not as bad as the photo (above) from the Mt. Wilson camera… but still gray. That’s not unexpected this time of year. May Gray is a well worn California phrase.

As it turns out, what looks like typical SoCal marine layer cloudiness is anything but! There are moderate to heavy radar returns from Central and Southern California.

The NWS office in San Diego describes it this way:

SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS THE MOUNTAINS AND DESERTS THROUGH THIS EVENING…WITH ISOLATED SHOWERS AND THUNDERSTORMS POSSIBLE WEST OF THE MOUNTAINS.

cali-radarThere are reports of street flooding in San Diego. Storm drainage isn’t very good in most older neighborhoods. It doesn’t take a lot to flood.

Even though these cells are moving in my direction it’s likely few (if any) will get here. The mountains east of us enhance the rainfall on the desert side, then stabilize the airmass as it moves back to lower elevations.

In SoCal people look forward to these gray days as a break from our endless sunshine. An OC native I spoke to yesterday was curious if I missed rain?

Right.

I wanted to say, “You’re nuts.” I held my tongue.

Actually, I feel gypped on days like today. Stupid attitude, but it is what it is. My mind has independently decided it’s supposed to be sunny and mild every day. I have no control over the letdown I truly feel.

By tomorrow we should be back to normal.

I’m Expecting To Be Busy With The Weather

The Storm Prediction Center was we’re in the ‘slight risk’ area for severe weather today. Whereas most government warnings overstate the problem SPC’s are usually too conservative. A slight risk area nearly always leads to a Severe Thunderstorm Watch area. Conditions certainly favor that.

SPC’s usual pattern is to post the risk area then later discuss the area in more detail with a Mesoscale Discussion. The only MD in effect as I type is for Maine.

The Storm Prediction Center says we’re in the ‘slight risk’ area for severe weather today. Most government warnings overstate problems. SPC’s preliminary advice is usually too conservative. A slight risk area nearly always leads to a Severe Thunderstorm Watch area. Conditions certainly favor that.

SPC’s usual pattern is to post the risk area then later discuss the area in more detail with a Mesoscale Discussion. The only MD in effect as I type is for Maine. MDs lead with watches.

…MID ATLANTIC/NORTHEAST… A BREAK FROM THE RECENT HEAT IN THE EAST WILL EVENTUALLY COME IN THE FORM OF A WEAK COLD FRONT THAT WILL CROSS THE APPALACHIANS TODAY AND MOVE OFF THE MID ATLANTIC SEABOARD BY EARLY SATURDAY. A VERY MOIST AND INCREASINGLY UNSTABLE AIR MASS WILL PRECEDE THE FRONT THIS AFTERNOON WITH SBCAPE LIKELY TO EXCEED 2000 J/KG FROM NC TO NYC. TSTMS SHOULD BECOME MORE COMMON AS CONVECTIVE TEMPERATURES ARE BREACHED EARLY AND LIFT WITH THE FRONT AND UPPER TROUGH SPREADS EAST ACROSS THE SPINE OF THE APPALACHIANS.

If/When we get storms the largest threat will be downburst winds and, of course, the lightning itself! It’s a bigger deal because of all the outdoor graduation ceremonies scheduled. People and lightning don’t mix!

The good news is there’s more comfortable air on the other side and it should be in place by Saturday morning.

See you on the TV this afternoon. I’ll be wrangling the weather on the FoxCT News at 4.

Today’s Thunderstorms – New Tools

These thunderstorms forming overhead gave me a chance to look at a new tool: The High Resolution Rapid Refresh model (HRRR). It’s your tax dollars at work.

We heard the first boom around 20 minutes ago.

“Hear the thunder?” Helaine asked. It was tough to avoid.

Over on Facebook Diane Campbell posted, “Just heard the loudest rumble of thunder I ever heard in my life! =(( scared me!”

It was in the forecast – phew! Bad weather isn’t so bad if it’s expected. That’s my very limited perspective.

These thunderstorms forming overhead gave me a chance to look at a new tool: The High Resolution Rapid Refresh model (HRRR). It’s your tax dollars at work.

The HRRR is the only hourly updated, radar-initialized, storm-resolving model running at this time over the US (or internationally), to our best knowledge. As a higher-resolution nest inside the hourly-updated Rapid Refresh the HRRR is designed to provide rapidly updated model guidance on convective storms for

  • air traffic management
  • severe weather forecasting
  • NOAA National Weather Service Warn-On Forecast
  • eventually provide improved background fields for NWS Real-Time Mesoscale Analysis
  • provide improved basis for other aviation hazard forecasts (e.g., wake vortex, ceiling, visibility, turbulence, inflight icing, terminal forecasts)

Allow me to cut through the mumbo jumbo. HRRR is very high resolution in both time (15 minute increment output) and space (3km resolution). It is a short range model that only goes out 15 hours from initialization. Since it takes a while to process you’re left with 12 or 13 usable hours.

Typically models give hints not full solutions. You can never take the exact placement of features as a given. I expect the HRRR will change that!

I am looking at the 1730z radar image and predicted radar image. They’re pretty close&#185. Not 100%, but much better than what I’m used to seeing.

If HRRR is as good as I hope these showers and thunderstorms will be gone by 5:30 pm (give or take a little).

Progress is good.

&#185 – Unfortunately, the maps are different domains and projections. That makes overlaying them impossible.

One Strange Weather Day

Through the evening broadcasts I kept a chance for thunder in and and sheepishly explained my reasoning. My bosses like me to be confident. It’s doubtful confidence was showing.

What a strange weather day. Nearly 100&#176 inland and mid-90s at the shore. Bradley broke a 45 year old temperature record early. Bridgeport set a record at 5:00 PM then broke it at 6:00! A little late in the day for record breaking warmth wouldn’t you say?

What was even stranger was the volatility of the atmosphere. For the past few days I’ve looked at the numbers and seen a powder keg. I use that analogy because powder kegs usually don’t explode, but they’re always potentially explosive.

Today was that kind of day. Last night I mentioned all we needed was a spark.

Meanwhile we motored through today with nary a cloud over Connecticut. As I prepared my forecast at 3:30 I considered taking the chance of thunderstorms out. I couldn’t do it.

I’m not sure I can explain what it was that kept me ‘on point.’ I suspect it’s experience at work. I’ve seen this kind of thing before… and been burned.

Through the evening broadcasts I kept a chance for thunder in and and sheepishly explained my reasoning. My bosses like me to be confident. It’s doubtful confidence was showing.

Then at 6:25 pm a lone cell popped up northeast of New London. It was tiny, but vicious. On the radar it went from green to deep red in under a mile. This was a cloudburst. In your car you’d see it ahead of you and drive directly into a wall of rain!

A few minutes later the Weather Service issued a severe thunderstorm warning for Southern New London County. Though the warning was valid until 7:15 it was quickly pulled as the cell collapsed into itself quashing the heavy rain.

It was the only thunderstorm cell that popped this afternoon. A towering cumulus cloud over Wallingford pictured at the top of this post (photo taken by Gil Simmons) never dropped its load.

Mostly what I do is objective. The same numbers produce the same results in my forecast.

Leaving the chance of thunder in was subjective. It was based on my knowledge of the area and formulated in such a complex manner I’m not sure how I knew to do it. I just did.

From Somewhere Over Central Florida

It’s been years since I threaded my way through Florida thunderstorms. That’s probably what’s on tap today.

“Eighty miles north of Tampa.” That’s the word from “Sully” up front. The ride is silky smooth now. The first hour was very choppy.

I can’t tell you what happened in between as I fell asleep while watching “This Week in Technology.” Sorry Leo.

There are light cumulus clouds under the plane. Off to the east (where we’ll soon be heading) things are more complex.

It’s been years since I threaded my way through Florida thunderstorms. That’s probably what’s on tap today.

Sleeptime is over. A short stop in TPA then southeast to FLL.

Addendum: We made it, but with a slow circle over the swamp! Within minutes of being airborne we were told there was a thunderstorm directly over Ft. Lauderdale Airport. Here’s the flightpath.