Monday, November 30, 2009

Hurricane Season 2009 Ends


November 30th marks the official end of the 2009 Atlantic Hurricane Season, which began June 1st. Here's a recap of this year's storms:

Tropical Depression One
Tropical Storm Ana
Hurricane Bill (max Category: 4)
Tropical Storm Claudette
Tropical Storm Danny
Tropical Storm Erika
Hurricane Fred
(max Category: 3)
Tropical Depression Eight
Tropical Storm Grace
Tropical Storm Henri
Hurricane Ida (max Category: 2)

That's nine named storms, three of which became hurricanes, two of which were major hurricanes. An "average" tropical season has 10.1 named storms, 5.9 hurricanes, with 2.5 of those becoming major hurricanes at Category 3 strength or greater.

So that means 2009 was slightly below-average for the number of named storms, with only half the average number of hurricanes. Still, of those few hurricanes that did form this year, two of them became major, which is about average.

We've talked about this previously on the blog, but El Nino is possibly one of the factors impacting the reduced number of tropical cyclones able to strengthen to hurricane status. The El Nino in the equatorial Pacific has been strengthening through the Summer and Fall months, which alters the upper-level wind patterns globally. This led to more wind shear (different wind speeds at different heights and directions) in the Atlantic, Caribbean, and Gulf, which disrupted cyclone organization. Shear prevents cyclones from strengthening uninhibited. Instead, the shear acts to "rip apart" the cyclone circulations, keeping most of this year's storms below hurricane status.

You can get the weekly update (Mondays) on El Nino here.

Saturday, November 28, 2009

Tracking Two Storm Systems

Two storm systems will bring an opportunity for rain to Central Virginia over the next week. The first will be a chance for showers (a quarter-inch of rain or less) as a cold front passes through the state on Monday. As of Saturday night, that front is moving through the Midwest and Plains. (See map below...click to enlarge.)
A second system will bring us another opportunity for rain Wednesday. Our Wednesday storm system is currently over the Southwest U.S. and is now cut-off from the upper flow that will steer the Midwest system toward us Monday. The Southwest low will gradually make eastward progress early this week, passing through the Southeast U.S. toward Virginia by Wednesday. This system looks like it will be the stronger of the two, with very gusty winds and heavy rain (1"-3") possible from Wednesday afternoon through Thursday morning. Here is a snapshot of what the system will look like around 1 a.m. Thursday:
See that tight pressure gradient over the Commonwealth? That should lead to wind gusts around 35-40mph from late Wednesday into Thursday morning.

Friday, November 27, 2009

Space Station Viewing Tonight


A great International Space Station viewing will occur tonight in Richmond from about 5:29-5:34 p.m. Just look Northwest to Southeast as the ISS passes directly overhead. Look for a bright white dot moving smoothly across the sky (at about 17,227 mph!). The ISS orbits the Earth 15.7 times per day at an altitude between 173 mi and 286 mi.
A few clouds may occasionally obscure your view of the Space Station, but skies will generally be clear enough to spot the light this evening. If you want to find the specific viewing opportunity for your location, click here.

Rainfall Overnight

Showers and thunderstorms moved through the state overnight with a strong cold frontal passage, and produced around an inch of rain in spots. Here are some totals:
Mostly sunny skies are expected the rest of Black Friday, with winds picking up from the Northwest at 15-25mph, gusting to 30mph at times. Skies will remain clear overnight with weakening winds, allowing temperatures in Central Virginia to fall into the low-30s with spots around freezing early Saturday morning.

Zach's Winter Outlook 2009-2010

In case you missed Zach's Winter Outlook for 2009-2010 Wednesday night, here are the details:

*Above normal temperatures & near-normal precipitation.
*More snow than last Winter, but still below normal.
*More ice this Winter than in recent years.

One of the main factors in the last statement is that the pattern setting up appears to have high pressure centered over New England. Low-level cold air thus moves south down the east side of the Appalachians right over Central Virginia. With moisture from the Atlantic and Southeast overriding that cold air, this is a perfect setup for significant ice storms. This should, therefore, lead to more ice this Winter than in the recent past.

SNOW: 9" predicted, most of which should come from one Nor'easter
ICE: Several minor ice events, with one significant ice storm
TEMPS: Above normal, with six days in the 70s in December, January, and February

Thursday, November 26, 2009

Showers and Storms Expected Overnight

A powerful upper-level storm system and associated cold front move through central Virginia tonight, resulting in numerous showers and isolated thunderstorms across the area. The strongest storms will produce small hail and wind gusts to 30 mph as well as occasional lightning. Much colder air will be moving into the area after midnight, and the rain could change to or mix with a few snow flakes before ending. If this were to occur in the Richmond metro area, the most likely time would be between 3 AM and 6 AM. All precipitation will come to an end around sunrise Friday, with mostly sunny and blustery conditions expected during the day.

Fog Update


The Dense Fog Advisory has expired for most of Central Virginia, but does remain in effect for the counties highlighted in orange until Noon. This does include the cities of Fredericksburg, Charlottesville, and Staunton. A Ground Stop program is still in effect for DCA, BWI, and IAD, and will likely remain in effect until late morning or mid-day. Click here for the latest on those airports.
Elsewhere in Central Virginia, patchy fog will linger until late-morning, when visibilities should be much improved.

Dense Fog Advisory Thanksgiving Morning


A Dense Fog Advisory is in effect until 9 a.m. for all of Central Virginia this Thanksgiving Morning. Northern Virginia into the D.C.-Baltimore areas will remain under the Dense Fog Advisory until Noon. The combination of damp ground from days of drizzle and showers, clearing skies overnight, and calm winds has led to many areas of dense fog developing. Visibilities widespread are below a half-mile, with many spots reduced to a quarter-mile. Conditions should improve mid-morning. Please use extra caution traveling this morning, allowing extra time to get to your destination, and also keeping your headlights on the low-beam setting. Here is the Richmond view from our Dominion Cam downtown. It looks more like San Francisco than Richmond!
And here's the view from downtown Petersburg.
If you're flying out this morning, be sure to check for flight delays at airports across the country here.
Here's a fog shot taken this morning by Ed Jones in Rawlings:
Be safe! And Happy Thanksgiving from the CBS 6 Storm Team!

Wednesday, November 25, 2009

November Rainfall Update

We already know that Richmond International Airport has recorded the wettest November on record (see previous blog entry), but we've continued to add to that rainfall tally yesterday and early Wednesday morning. As of 7 a.m., November 2009 at RIC has 8.11" of rainfall. We've surpassed the old record-holder of 1959 by about half an inch! That's pretty significant for breaking a record. And, there's still that persistent drizzle this morning, which will keep adding to that monthly total.

So where do we stand for the year?

Year-to-date precip: 38.67" (through 7 a.m. Wednesday)
That's -1.52" departure from normal for year-to-date precipitation.

Tuesday, November 24, 2009

Wettest November On Record!

A light rain shower passed right over Richmond International Airport overnight between 3-4 a.m., pushing our November rain tally over the #1 spot to become the wettest November on record! Through 6 a.m., our November 2009 tally stands at 7.96", and as of this blog posting, we still have drizzle falling in the Metro. Here is the new November list:

2009: 7.96" (through 6 a.m. Tuesday)
1959: 7.64"
1947: 7.03"
1985: 6.99"
1962: 6.73"
1963: 6.70"

Monday, November 23, 2009

Strong But Seasonable Cold Front Coming


Just in time for the holiday season, a strong, but seasonable, cold front is expected to sweep through much of the eastern U.S. Thanksgiving Day. The front will pass through Central Virginia before sunrise Friday as the low pressure system tracks toward New England. Here is the surface temperature, pressure, and wind map for Friday morning:
Behind that front on Friday, highs will only climb into the upper 40's to near 50 degrees in Central Virginia, and it will feel a bit more chilly as a result of the blustery winds. If you're planning to shop on Black Friday, be sure to take that light coat with you.

Thanksgiving Travel Highlights:
Wednesday: Cloudy, drizzle possible, High: 60 in Richmond.
*Rain & Snow showers in Midwest.
*Drizzle & Showers possible from North Carolina to D.C.-Baltimore area.
*Rain in Florida.

Thursday: A few showers possible late. Otherwise cloudy, High: 59 in Richmond.
*Showers possible in Mid-Atlantic.
*Few snow showers possible in Midwest.

Friday: Turning colder, High: 50 in Richmond.
*Rain & Snow showers in New England & Midwest.
*Rain & Snow showers possible in West Virginia, eastern Kentucky & Tennessee.

Saturday: Cold morning around freezing, seasonably cool afternoon in the low 50's in Richmond.
*Rain & snow showers possible in New England.
Have safe travels this holiday!

Sunday, November 22, 2009

Foggy For Some This Morning

Check out all the fog on our Skytracker camera this morning in Petersburg.


Patches of low-lying fog will linger around the area for the next couple hours, but should lift by late morning.

Thursday, November 19, 2009

This November Now Our 4th Wettest

We received 0.16" of rain today at RIC which brings our monthly total to 6.79". This total-so-far ranks November 2009 as the 4th wettest November on record for Richmond. Here are the top three:

#3 6.99" (1985)
#2 7.03" (1947)
#1 7.64" (1959)

We have another good opportunity for rain late Sunday which could vault us into the #2 spot.

Wednesday, November 18, 2009

El Nino Strengthening

Over the last four weeks, sea surface temperatures along the Equator west of South America have been increasing, strengthening the ongoing El Nino (which began in April 2009). Sea surface temperatures are now well above-average in that region (see map below). Not only is it warmer on the surface of the Equatorial Pacific, it is also warmer deeper in the Ocean.

Sea surface temperatures are now about +1.7 degrees F above average in the region, indicating a strong El Nino. And El Nino is expected to strengthen further in coming weeks, maintaining moderate to strong El Nino conditions at least through the Northern Hemisphere Winter months.

The below image illustrates the typical Winter that occurs during an El Nino, such as we are about to enter:

This would mean for Central Virginia slightly cooler temperatures and more snow (December-March), based on 12 previous moderate El Nino events. However, if the last four week trend of SST continues, we may experience the opposite impacts! Since 1950, only four strong El Ninos have occurred, all four resulting in Richmond's annual snowfall being below average with above average temperatures. This is the opposite result of what tends to occur in a weak to moderate El Nino Winter.


RIC Big Snowfalls: Past 30 Years
Jan 1980 14.9" Neutral
Mar 1980 13.0" Neutral
Feb 1983 17.2" El Nino
Jan 1996 11.5" La Nina
Jan 2000 12.5" La Nina
Mar 2009 6.3" Neutral

Another factor to consider right now is the amount of snowpack in North America. Here are the snowpack maps from 2001-2009 in mid-November:

Notice this year's map looks similar to 2001, 2004, 2006, and 2007, which resulted in roughly warmer-than-average Winters in Central Virginia. What is more significant, perhaps, is how similar 2009 and 2001 are to each other in snow-coverage. The Winter of 2001-2002 was the 7th warmest on record.
Any cold fronts we receive in the coming weeks will not be moving over a large southward snow-covered surface to our northwest, which means they loose some of their "punch" and are unable to advect as cold of air to Central Virginia.

--Blog entry by Chief Meteorologist Zach Daniel, and Meteorologists Aaron Justus and Carrie Rose.

Tuesday, November 17, 2009

Patchy Dense Fog This Morning

After last week's rains, there is still ample low-level moisture to serve as "fuel for fog" this Tuesday morning. We had clear skies overnight with lighter winds, as well, and that allowed patchy fog to develop in spots. Where fog has developed, it has become dense, with visibilities being reduced below a half-mile in many places, especially south of I-64 from Richmond, and south of Petersburg into North Carolina. As of 6 a.m., the visibility at Emporia and South Hill is just a quarter of a mile. I expect the fog to last through sunrise, and for the spots where it is dense, it may take until mid-morning to fully lift.

Monday, November 16, 2009

Leonid Meteor Shower Forecast

The Leonid Meteor Shower is set to peak early Tuesday morning, November 17th. However, in North America there will be just a "sprinkling" of meteors in the pre-dawn sky, with about 20-30 expected per hour. That's pretty slim pickings for a meteor shower. But if you want to try to catch some of the brilliant meteors streaking across the sky, head outside Tuesday morning from 4 a.m. until sunrise at 6:51 a.m. Patchy fog may be around early tomorrow, but visibility should be alright elsewhere, especially since the Moon is New (i.e., no Moonlight to obscure the meteor light). Looking for Leonids is pretty simple. Just look straight up!

(Image: NASA)
Even though North America's Leonid forecast is less than stunning, it will be spectacular for Asia, where as many as 300 meteors per hour will likely occur! That's an impressive meteor shower!
(Image: Danielle Moser of the NASA Meteoroid Environment Office)
Asia gets the best show because that side of the Earth will smack into the densest debris field left behind by Comet Tempel-Tuttle. The Earth passes this comet's stream of debris on our solar orbit every November, and the resulting meteors appear to originate from the constellation Leo. One extra visual feature of this year's display is that brilliant Mars will be next to Leo.

Sunday, November 15, 2009

Patchy Fog This Morning

Visibilities have dropped below a mile in some locations across the region. Luckily this fog should lift by late morning.


Here's a look at some of our Skytracker cameras in our area:

Downtown Richmond

Richmond airport


Downtown Petersburg

Richmond Zoo

Friday, November 13, 2009

Latest Warnings & Storm Total Rainfall


Flood Warnings remain in effect for many counties in Central Virginia until further notice. The widespread heavy rain event is beginning to wind down, but there are still gusty winds and light rain and drizzle affection the region from that coastal low pressure system off of the Outer Banks. High pressure remains stubbornly parked over New England, and that pressure difference between the northern High and the coastal Low are still creating gusty winds along the Mid-Atlantic coastline. A Wind Advisory remains in effect for the eastern Peninsulas and the Chesapeake Bay to the Virginia Atlantic Coastline for gusts around 40mph.


Here are the peak recorded wind gusts from the event (these occurred Thursday):
Oceana 75mph
Norfolk 74mph
Cape Henry 72mph
Chesapeake Bay Bridge Tunnel 71mph
York River Lighthouse 66mph
Rappahannock Lighthouse 61mph
Wallops Island 59mph

Here are some of the latest storm total rainfall amounts in Central Virginia;
Chesapeake 11.92"
Hampton 11.86"
Langley AFB 10.58"
Oceana 10.29"
Newport News 9.88"
Portsmouth 8.71"
Norfolk 7.41"
Wakefield 6.40"
Hanover 6.06"
Suffolk 6.03"
Chester 5.60"
Richmond 5.44"
Glen Allen 5.01"
Petersburg 5.00"
Farmville 4.53"
Wallops Island 4.37"

Richmond Marathon Affected By Flooding?

I was just checking the path of the Richmond Marathon and it looks like part of the race is on Riverside Drive. Here is a Google Streetview of the area:



This is obviously a low-lying area that will be prone to flooding. If you are racing tomorrow, you will want to check with race officials to see if the course will be changed.

James River At Westham