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Feb 21-22 Snow/Sleet Storm Obs/Nowcasting/Weenie/Panic/Hallucinations


Ji

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Ji mentioned this storm could be son March 1999 over in the model thread.

From http://www.erh.noaa..../va-winters.htm

Other types of weather systems generally do not cause major problems for Virginia. Storms such as the "Alberta Clipper" (a fast moving storm from the Alberta, Canada region), or a cold front sweeping through from the west, generally do not bring more than 1 to 4 inches of snow in a narrow 50 to 60 mile-wide band. Sometimes, the high pressure and cold arctic air that follow in the wake of a "clipper" becomes the initial set up for the "nor'easter." In very rare cases, elements combine to produce very localized heavy snow without any fronts or storm centers nearby. These events are nearly impossible to forecast with any accuracy. One such event occurred in Northern Virginia on March 9, 1999. An unexpected 9 to 12 inches of snow fell in a very narrow band through a very heavily populated and well traveled corridor (Winchester to Middleburg to Fairfax to Alexandria).

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Should help with the sting of this horrid winter.

Not sure what your climo snowfall is, but if this storm verifies for MBY (3-6"), that gets me just under seasonal climo (~24"). Combined with 2 months below normal temp wise, and I'd give this winter a solid B. Hell...thunder sleet alone might make it a B+.

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Not sure what your climo snowfall is, but if this storm verifies for MBY (3-6"), that gets me just under seasonal climo (~24"). Combined with 2 months below normal temp wise, and I'd give this winter a solid B. Hell...thunder sleet alone might make it a B+.

as of right now, I'd give this winter a B for bogus

if this verifies, well...I'll let you know :P

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You could probably do a very rough back-of-the-envelope calculation:

Say this storm is affecting 20,000 km^2...snow falls at...oh...10 snowflakes per m^2 per second. Storm lasts 6 hours.

That's about 4*10^15 snowflakes...that's 4 quadrillion :snowman:

Well, if we are gonna go there....I've often thought about the enormous energy involved in lifting/suspending these quantities of water thousands of feet above the ground. Last year, as I shoveled the snow after Feb 5, and marveled at the weight of one shovel full, I just kept thinking this.

One inch per hour snowfall would require a volume of 1/40 of a meter cubed (one inch being about 1/40 of a meter). That would be a volume of about 25 liters, or 1/40 the volume of a meter cubed (1000 liters). If one flake is a cm square, and one mm thick, it has a volume of 1/10 of a ml. 10 flakes would be required to give a ml of snow. 25 liters is 25 times 1000 ml or 25000 ml. This would be 250000 flakes in one hour, or about 70 flakes per second. More if the flakes were smaller. So multiply your total by 7, or about 28 quadrillion. But what's a few quadrillion flakes among friends? :thumbsup:

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Well, if we are gonna go there....I've often thought about the enormous energy involved in lifting/suspending these quantities of water thousands of feet above the ground. Last year, as I shoveled the snow after Feb 5, and marveled at the weight of one shovel full, I just kept thinking this.

You can think of it potential energy terms:

20,000km^2 with a liquid equivalent of 1cm over that entire area is 2*10^8 m^2 of water. Water has a density of 1000kg/m^3...so that's 2*10^11 kg. PE = mass * gravitational acceleration * height... Assume an average height of 500m and you get...about 10^15 Joules. 1 quadrillion Joules. :arrowhead:

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You can think of it potential energy terms:

20,000km^2 with a liquid equivalent of 1cm over that entire area is 2*10^8 m^2 of water. Water has a density of 1000kg/m^3...so that's 2*10^11 kg. PE = mass * gravitational acceleration * height... Assume an average height of 500m and you get...about 10^15 Joules. 1 quadrillion Joules. :arrowhead:

Awesome. Hey, look at my post again. I edited it after you saw it. See what you think.

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41.5/36.....down from a high before 10am of 58.7. Much higher and thinner overcast now. During the push of cold this morning, I left Woodbridge, right around where the Potomac Nats play (Prince Wm Pky and Old Bridge Rd) and it was 48 on the car thermo. About 1 mile north at Hoadly Rd the temp plummeted down to 41 with the shower and was jumping between 41 and 39 all the way up to Herndon. On the way back, nearly steady from Herndon to my house. Between 40-42 as things have leveled off. Pretty cool little push. So the nearly 60 progged high temp did verify for us folks down here and certainly down south.

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Ji you are in

Winter Storm Warning

URGENT - WINTER WEATHER MESSAGE

NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC

235 PM EST MON FEB 21 2011

MDZ009>011-014-VAZ031-042-220345-

/O.UPG.KLWX.WW.Y.0009.110222T0200Z-110222T1200Z/

/O.EXB.KLWX.WS.W.0004.110222T0200Z-110222T1200Z/

MONTGOMERY-HOWARD-SOUTHERN BALTIMORE-ANNE ARUNDEL-CLARKE-LOUDOUN-

INCLUDING THE CITIES OF...GAITHERSBURG...COLUMBIA...BALTIMORE...

ANNAPOLIS...LEESBURG

235 PM EST MON FEB 21 2011

...WINTER STORM WARNING IN EFFECT FROM 9 PM THIS EVENING TO 7 AM

EST TUESDAY...

THE NATIONAL WEATHER SERVICE IN BALTIMORE MD/WASHINGTON HAS

ISSUED A WINTER STORM WARNING FOR SNOW AND SLEET...WHICH

IS IN EFFECT FROM 9 PM THIS EVENING TO 7 AM EST TUESDAY. THE

WINTER WEATHER ADVISORY IS NO LONGER IN EFFECT.

* PRECIPITATION TYPE...BRIEF PERIOD OF SLEET...CHANGING TO SNOW

AROUND MIDNIGHT WHICH WILL BE HEAVY AT TIMES OVERNIGHT.

* ACCUMULATIONS...4 TO 8 INCHES OF SNOW. WITHIN THIS RANGE...THE

HIGHER AMOUNTS WILL BE IN THE NORTHERN PART OF THESE COUNTIES.

* TIMING...WINTRY MIX OF RAIN AND SLEET WILL BEGIN LATE THIS

EVENING...THEN CHANGE OVER TO ALL SNOW AROUND MIDNIGHT. THE SNOW

WILL CONTINUE UNTIL DAWN. THE HEAVIEST SNOWFALL IS EXPECTED

BETWEEN 1 AM AND 5 AM.

* TEMPERATURES...TEMPERATURES IN THE MIDDLE 30S THIS EVENING...

DROPPING TO THE UPPER 20S BY TUESDAY MORNING.

* WINDS...NORTHEAST 10 TO 20 MPH.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW...

SLEET...AND ICE ARE EXPECTED OR OCCURRING. STRONG WINDS ARE ALSO

POSSIBLE. THIS WILL MAKE TRAVEL VERY HAZARDOUS OR IMPOSSIBLE.

&&

$$

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Does a strong temp gradient like this aid in the amount of precip? Anybody?

Not per se. Frontogenic forcing is a factor people often look at for ID'ing the heaviest precip bands and strengthening storms, etc.

Here's a quote from a storm summary from an AZ WFO...

Areas of frontogenesis typically lead to

more intense precipitation rates due to enhanced secondary circulations that are not

handled well by numerical models. This means that forecasters need to identify areas of

frontogenesis to anticipate the potential for banded precipitation, along with the

associated intense precipitation rates and accumulations, which will not be shown by

numerical model solutions.

www.wrh.noaa.gov/wrh/talite0437.pdf

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