Tuesday, November 26, 2013

UPDATE: Significant SNOW for NE Ohio!!!


Courtesy: Cleveland Public Safety


First, some clarification on winter watch/warning definitions: A WINTER STORM WATCH means there may be hazardous winter weather due to heavy snow. Heavy snow means 7 INCHES OR MORE of accumulation in 24 hours or less. They are issued at least 12 hours before the hazardous winter weather is expected to begin. When the storm becomes imminent (inside 12 hours of occurring) or has a high probability of occurring, watches are upgraded to a "WARNING" which was done yesterday for select counties.

Leading edge of the snow is pushing into southern Ohio. CLICK ON THE IMAGE BELOW FOR THE CURRENT RADAR OVER OHIO

 
http://www.intellicast.com/National/Radar/Current.aspx?location=USOH0245&animate=true

The timing of the snow looks like this: SNOW IN AKRON/CANTON/NEW PHILLY BY 2PM, CLEVELAND BY 3PM. AFTER THAT, THE SNOW SLIDES WEST.


Accumulations from TUESDAY LATE AFTERNOON through WEDNESDAY LATE AFTERNOON look like this. Most of this will fall this evening and tonight:

Hazardous travel through western PA and western NY state. The major airports along the east coast will only see rain from this system. Any flight delays will trickle down from the inland airports like Hopkins in Cleveland, Pittsburgh, Buffalo and Rochester.


Monday, November 25, 2013

Nor-Easter Developing: Heavy Snow Imminent


WINTER STORM WARNING FOR ASHTABULA, GEAUGA, TRUMBULL, PORTAGE, STARK, MAHONING AND TUSCARAWAS COUNTIES FROM 12PM TUESDAY TO 4AM THURSDAY. First, some clarification on winter watch/warning definitions: A WINTER STORM WATCH means there may be hazardous winter weather due to heavy snow. Heavy snow means 7 INCHES OR MORE of accumulation in 24 hours or less. A "WATCH" is a long range prediction. They are issued at least 12 hours before the hazardous winter weather is expected to begin. When the storm becomes imminent (inside 12 hours or occurring) or has a high probability of occurring, watches are upgraded to a "WARNING"

The active pattern continues in the month of November. We've already had a little over 3 inches of snow at Hopkins (more in the snowbelt), the most since 2008 through the 25th of November. Our high temperature Sunday of 26 was the coldest daytime high AFTER the 20th since 2005 when we only hit 24 on the 25th. Prior to that, you have to go way back to 1976 to find a colder high temperature during the last 10 days of November.

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Now for the setup this week: The 500 mB steering currents show a trough digging across the east. Notice that the clipper low is starting to phase with the panhandle low to the south. So that by Wednesday afternoon, both lows are completely absorbed into the mean somewhat negatively tilted trough. In conditions like this, the low can amplify (get stronger) very fast due to the sharp variations in conditions to either side of the trough.  Higher levels of instability can develop which can create bursts of heavy snow. Fortunately, I think that this will occur in western PA and upstate NY.

MONDAY EVENING
TUESDAY EVENING
WEDNESDAY AFTERNOON
The US radar is already showing the merging of the two systems...
 

The snow from the clipper will be the first wave of light snow tonight. Accumulations will be small, perhaps an inch in spots by early Tuesday morning.


The future radar loop (high resolution NAM 4 km) shows distinctly the clipper snow coming in from the northwest, a break, followed by the panhandle snow/rain from the southwest. Here is the youtube clip. Watch the time clock at the top of the video. 


Heaviest snowfall amounts still seem to reside in the eastern counties closest to PA. The latest bring back some of the heavier snow west. Here is our updated snowfall forecast. The NWS forecast is lining up very well with our forecast so I'll go with their numbers. Remember, this is just guidance as snowfall will vary a bit from place to place.









Saturday, November 23, 2013

Why is Lake Effect So Localized?

Why is lake effect snow so localized? Moisture often times converges in pockets or streaks depending on the weather setup. Check out this great visible satellite photo which shows the streaks of clouds cover and sunny breaks in between. Each streak of cloud cover has bursts of lake effect embedded within it.

BTW, the 850 mB temperatures will be falling to -18 with a lake water temperature of +8 (yes, all in celsuis). You need around a 13 degree temperature difference. Notice that later today, tonight and early tomorrow, temperature differences approach 25! This means heavy bursts of snow IN LOCAL AREAS!


Saturday afternoon radar image...CURRENT NORTHERN OHIO RADAR LOOP HERE


Tuesday, November 19, 2013

How Rare Are "NOVEMBER SEVERE WEATHER HIGH RISK" Forecasts? VERY!

Damage from Washington, Illinois (Chicago Tribune)
Several requests on the history of MODERATE and HIGH RISKS for the US and OHIO in November. I found some answers on the Storm Prediction Site.

Only 2 other instances where the Storm Prediction Center issued forecasts for HIGH RISK FOR SEVERE WEATHER in November:  2002 and 1998.  None of these HIGH RISKS were for any part of Ohio. Both of these featured large tornado outbreaks.

Image courtesy Greg Carbin, SPC
This is what Sunday's event looked like with storm report dots superimposed over the risk areas

Image courtesy: Eric Fisher/Jesse Ferrell on Twitter
Only 10 MODERATE RISK AREAS have been issued in November since 1998. 4 of the 10 were issued on the same date or later in the month. NONE WERE ISSUED IN OHIO!!!

Image Courtesy Greg Carbin, SPC

Aerial Photo of Tornado Path in Washington, Illinois


Notice the swirls along the path. This tornado was on the ground for 46.2 miles a an EF4 which had winds between 170-190 mph. This tornado had winds greater than any hurricane or Typhoon in recorded history!

Here are some other aerial photos courtesy of the Chicago Tribune.




Monday, November 18, 2013

Crying Wolf? I Think Not: Severe Weather Definitions

It never fails.

During and after each and every severe weather event, there are a few people that selfishly say "Where are the storms? You all said we'd have severe weather. All we're getting is wind and some rain. You weather people never get it right!" Nothing gets me more fired up more than idiotic comments like this. Tell this to the families who lost loved ones in this house in Nashville, Illinois.



My blood pressure is climbing just writing this......errrrrr!

I have written many times about how our perceptions and preconceived notions tend to govern our thoughts especially when events occur that seem to support and reinforce our biased notions. I try to tell these individuals that severe weather forecasts are approximations. That's why tornado watches are as large as a state not a city. 

People will think the way they want to think regardless of how much data you present them to the contrary.  How often have our biases surfaced during election years (economic issues), in our day-to-day lives perhaps when we interact with others?  See my posts about cognitive biases and  cognitive dissonance relating it to weather HERE and HERE. Note the parts in red print if you want the Cliffs Notes version.

Anyway, maybe these basic severe weather definitions will clarify some of these misconceptions and perceptions about severe weather. Bottom line is this: When the Storm Prediction Center has a region in a MODERATE to HIGH RISK for severe weather, bad things will happen. This is not something to be taken lightly.


 

Sunday, November 17, 2013

OHIO SEVERE WEATHER UPDATE: 8PM


TORNADO WATCH still in effect for all of northern Ohio until 12AM. This means CONDITIONS are still FAVORABLE. No confirmations of any touchdowns in northern Ohio. Watch might be cancelled before 12AM. Stay tuned...


CHECK OUT MY TWITTER FEED FOR ANY WARNINGS ISSUED

Earlier today, updates here projected the main line of storms to be approaching western areas of Ohio by 6PM. Here was this initial map created by the HRRR model.


Here is the radar image at 8PM...line is moving a bit faster CLICK ON THE RADAR IMAGE FOR THE CURRENT RADAR LOOP OVER OHIO

http://radar.weather.gov/radar_lite.php?rid=cle&product=N0R&loop=yes

Between 8 and 10PM, expect fast moving (50-60 mph) storms across northern Ohio. Some will be severe

By 10PM, the majority of the storms should be out the area...



Notice the temperature drop behind the front circled in BLUE.


We'll wake up to temps in the lower to mid 40s Monday morning.




SEVERE WEATHER UPDATE: Sunday NOON UPDATE

Everything is still pointing to a HIGH POTENTIAL for severe thunderstorms THIS AFTERNOON AND THIS EVENING.

TORNADO WATCH ISSUED FOR NORTHERN INDIANA, FAR WESTERN OHIO UNTIL 8PM


Remember, a SEVERE STORM is a storm with 58 mph winds AND/OR 1" hail or a tornado. When any one of these criteria are met, a SEVERE THUNDERSTORM WARNING is issued. A TORNADO OR SEVERE THUNDERSTORM WATCH means conditions are favorable. WARNING means its occurring now!

RADAR SNAPSHOT AT OF 11:30AM


CLICK HERE TO SEE THE MOST RECENT RADAR LOOP

Plenty of sunny breaks which will only destabilize the atmosphere which will promote more storm development. Visible satellite image here...


The discussion posted here yesterday still holds:

High resolution HRRR model brings the main line of strong/severe storms into western Ohio by 6PM...8PM across northern Ohio


Storm Prediction Center has shifted the MODERATE and HIGH RISK area further east. HIGH RISK now in western Ohio!!!

To put this into perspective, Ohio is put into a HIGH risk SEVERE WEATHER area about once every 3-5 years. 

Tornado chances seem higher in Illinois and Indiana
Super strong jet stream...left front exit region over Lake Erie
Upper level diverging air at 500mB (18,000 feet) which translates into rising air at the surface.
A very large temperature gradient. Sunday morning temperatures are already pushing 60 across northern Ohio
All of these conditions will produce very strong winds at the surface in excess of 40-45 mph later today.

Saturday, November 16, 2013

Severe Storms VERY Possible Across OHIO SUNDAY AFTERNOON

The Storm Prediction Center has painted OHIO in a Moderate Risk for Severe Storms SUNDAY. To give you an historical reference point to what this means, OHIO usually goes under a MODERATE RISK only a few times a year. Bottom line, don't take this threat lightly.

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Remember, a SEVERE THUNDERSTORM is a storm with 58 mph winds AND/OR 1" hail or a tornado. When any one of these criteria are met, a SEVERE THUNDERSTORM WARNING is issued.

Here are the meteorological parameters for tomorrow:

Super strong jet stream...left front exit region over Lake Erie


Upper level diverging air at 500mB (18,000 feet) which translates into rising air at the surface.
Pocket of HIGH surface winds across northern Indiana and Ohio exceeding 40-45 mph.
. Sharp temperature gradient...

Expect a fast moving squall line (embedded severe storms) late Sunday afternoon into the early evening Sunday. The timing a strength of the line of storms will need to be monitored.


Tuesday, November 12, 2013

Snowcover Photos from Across Northern Ohio

Now that the cold front has passed, the lake effect has begun with winds out of the NORTH Current RADAR LOOP shows localized lake effect as far west as Norwalk and as far south as Canton.

RADAR LOOP HERE
 
An atypical fetch for lake effect but one that we saw frequently back in the winter of 2009-2010. See my previous post on the DIFFERENT FLAVORS OF LAKE EFFECT SNOW.

Since the cloud are low level clouds with limited moisture, it doesn't take much wind to break up the clouds enough for some breaks of sunshine.

 That partial sunshine made for some nice photos from FOX8 viewers earlier today.

Akron, Ohio snow

Austinburg, Ohio
Carrollton, Ohio
Mayfield Heights
Penfield, Ohio
Rittman
Canton
Hudson