Wednesday, November 28, 2012

Snow in the East, Another Stormy Period for the West

Surface map for 7:00 a.m. EST November 28.
It has been a cold but dry week across the middle of the U.S., while two storm systems book-ended the lower 48 states. On Tuesday a low pressure system with a trailing cold front brought precipitation to an area from Mississippi up through southern new England. Rainfall amounts were around an inch along the Gulf Coast, but less than half that up through the southeast U.S. The other area of significant precipitation was the mid-Atlantic coast, particularly New Jersey.  Two to four inches of snow covered the ground in the northwestern half of New Jersey and parts of southeastern Pennsylvania this morning.  Lighter snow amounts were reported north through New York and new England.

CoCoRaHS precipitation map for November 28.

Another stormy period is ahead for the Pacific Northeast this rest of this week. CoCoRaHS observers will get another good workout for their rain gauges, with perhaps as much as 6 to 12 inches of rain expected in the next several days, especially in northern California and Oregon. Heavy snow is expected for the next several days in the higher elevations of the Shasta, central and northern Sierra Nevada, and Sawtooth mountain ranges.

Left:  5-day Quantitative Precipitation Forecast.  Right: Probability of >8 inches of snow in 48 hours
Forecasts issued by the NWS Meteorological Prediction Center.

In the meantime, there will be significant warming across the central and eastern U.S. through the weekend. The snow currently on the ground in New Jersey will just be a memory by the weekend.

However, this could be the last period of mild weather for awhile for the eastern two thirds of the U.S. It appears that cold air will likely spread over the U.S. east of the Rockies by the middle of next week, and may be followed by several reinforcing pushes of cold air in the days to follow.

Tuesday, November 20, 2012

Storms Slam into Pacific Northwest

While most of the country has enjoyed tranquil weather for the last week or so (evidenced by the many gray dots on the CoCoRaHS national map), the Pacific Northwest has been pounded by a series of storms that have brought hurricane-force winds, torrential rain, and heavy snow. Flooding closed roads, winds toppled trees which in turn brought down high voltage power lines, heavy rain caused mudslides, and the avalanche danger was high from the heavy snow.

The first of these storms moved ashore from the Pacific on Saturday, followed by another on Monday.

Surface map for Saturday, November 17 (L) and for Monday, November 19 (R).
 The 7-day precipitation accumulation map shows accumulations ranging from five to more then ten inches all along the Oregon and Washington coasts.  Most of that precipitation came with Monday's storm, which has been the most intense one so far.

7-day precipitation accumulations through 5:00 a.m. PST November 20
CoCoRaHS observers in Oregon reported more than nine inches of rain.

CoCoRaHS map for Curry County in southwestern Oregon for November 20.
A number of observers in Oregon noted that today's rainfall was the highest 24-hour amount they have ever recorded. The general nature of the rain and flooding apparent from this comment from the CoCoRaHS observer at Oakridge 4.6 NE in Lane County who measured 4.03 inches of rain:

Nope that's not a typo, we did get over 4" and almost all of that came after 5 PM. It rained off an on during the day but never heavily, less than a 1/2" before 5, and then it started really raining. We don't get flooding up here to speak of. Compared to other areas what we have right now is minor, but it is significant for us. I marked the flooding as minor because on an absolute scale that's what it is, but it is not typical for us. Last time I saw this sort of general standing water on our property was the heavy rains the winter of 05-06. We have had heavier flooding in the area, but from creeks overflowing, not just general standing water. The creeks are high right now, but not overflowing. 

Washington also received heavy rain, and there were a number of new daily rainfall records, including daily rainfall records at the Seattle-Tacoma International Airport (2.13", old record 1.23" in 1962) and at the National Weather Service Office 2.60". old record 1.16" in 2003).

CoCoRaHS map for King County, WA for November 20.
There were many wind gusts in excess of 70 mph reported yesterday with this storm. Here are a few of those gusts.

114 mph      Naselle Ridge in the mountains of southwest Washington
106 mph      Mt. Hebo nearTillamook, Oregon
101 mph      Astoria bridge, Washington
101 mph      Megler, Washington 
  98 mph      Yaquina Head, Oregon
  92 mph      Astoria, OR
  90 mph      Garibaldi, Oregon

It appears the stormy weather will continue through the end of the week. A third storm will hit the Pacific Northwest Wednesday, and yet a fourth storm is forecast to arrive on Friday. Additional rainfall of one to three inches is expected from Washington south through northern California and a foot or more of new snow in the high Cascades and the northern Rockies by Wednesday night.

Forecast surface map for the morning of Wednesday, November 21

Wednesday, November 14, 2012

November Snow

Winter weather has come early to the lower 48 states this year.  First there was the heavy snow in the Appalachians associated with Sandy, and then heavy snow in New Jersey and southern New England with the nor'easter the following week. While attention has been focused on the east, snow has been falling with some regularity in the western U.S. In fact, snow cover across the northwestern quarter of the lower 48 states is above normal for this time of year.

There are a number of online resources for following snowfall across the U.S., and in fact across the northern hemisphere.  The National Operational Hydrologic Remote Sensing Center website has an entire suite of products dedicated to monitoring snowfall, snow depth, and related measurements across the U.S.  Here is the depiction of snow depth across the U.S. as of this morning. This map is based on modeled snow pack characteristics updated each day using all available ground, airborne and satellite observations.  Note that the model analysis can be off in places. For example, the snow depicted in central and northwestern Illinois is overdone, and may be just a trace in a few spots.

 The NOAA U.S. National Ice Center also monitors ice and snow cover across North America and the Northern Hemisphere. This analysis shows only where snow is on the ground, and does not show snow depth.

For a view of the Northern Hemisphere in somewhat more detail, the Rutgers University Global Snow Lab provides a suite of charts and graphs that monitors snow cover. A nice feature of the Global Snow Lab are the snow climatology maps and the departure maps, which show where snow cover is above or below normal as of a certain date. Note that like the National Ice Center maps, these maps depict the extent of snow cover and do not provide any information on snow depth.

Maps from the Rutgers University Global Snow Lab for November 13, 2012

Of course, last but not least are CoCoRaHS maps. The national map from Tuesday morning clearly shows snow on the ground in the west as well as the upper Midwest and northeast..

 The greatest snow depths on the CoCoRaHS maps were found just east of Salt Lake City, where 7 to 13 inches of snow covered the ground as of Tuesday morning.

Snowfall and snow depth measurements from CoCoRaHS observers are needed and used by variety of people monitoring snow across the country from the National Weather Service to municipalities to snow removal services. Now is the time to review and refresh yourself on snow measurement procedures. The snow measurement training program is available on the CoCoRaHS web site, and the Snow Measurement webinar video is available on YouTube.

Saturday, November 10, 2012

"When the gales of November came slashin'... "

Today is the 37th anniversary of the sinking of the Great Lakes freighter the Edmund Fitzgerald. The first time I really became aware of this incident was when I first heard Gordon Lightfoot's haunting ballad "The Wreck of the Edmund Fitzgerald".  The Great Lakes have a long history of intense fall and winter storms and the wrecks of hundreds of ships litter the lake bottoms.  The weather during the fall can quickly go from good to very bad, and such was the case in November of 1975.

Surface map on November 6, 1975
The week of November 3 was unseasonably warm week across the eastern two-thirds of the country. A surface ridge of high pressure stretched from the southern tip of Texas to Quebec, Canada keeping the eastern two-thirds in southerly flow.  In the days leading up to November 10, 1975 temperatures reached the middle 60s as far north as the Minnesota-Canadian border.

In Superior, Wisconsin the Edmund Fitzgerald was loaded with more than 26,000 tons of taconite pellets destined for a steel mill near Detroit. The weather while the Fitzgerald was in Superior was, well, superior. Temperatures early in the week reached 74°F, and when the Fitzgerald left port at 4:30 p.m. on November 9 the temperature was in the 50s°F and skies were cloudy.  She soon joined up with the Arthur M. Anderson, another freighter which left Two Harbors, Minnesota bound for Gary, Indiana.

Surface map for the morning of November 9, 1975

At 7:00 p.m. the National Weather Service issued gale warnings for Lake Superior, forecasting E to NE winds during the night, shifting to NW to N by the afternoon of November 10.  At approximately 10:40 p.m. the NWS revised its forecast for eastern Lake Superior to easterly winds becoming southeasterly the morning of the 10th. At about 2:00 am November 10 the NWS upgraded the gale warning to a storm warning with a prediction of "northeast winds 35 to 50 knots becoming northwesterly 28 to 38 knots on Monday, waves 8 to 15 feet".  The captains of the two freighters decided to take a route closer to the Canadian shore which would protect them from the northeast winds.

The surface weather map for the morning of
November 10, 1975, about 12 hours before
the Edmund Fitzgerald sank.
The center of the storm passed over Lake Superior on the morning of November 10. As the center of the low passed over the ships the Anderson reported winds dropped for a time to 5 mph. As the low moved to the northeast, the winds shifted into the south, then west and northwest and rapidly increased speed. Visibility dropped as snow began falling in the cold air plunging south behind the storm. The observed winds by the Anderson and by the Stannard Rock Weather Station during the afternoon of November 10 were from 40 to 58 knots from the west-northwest, gusting to 65 knots. The Anderson also observed wave heights of 18 to 25 feet during the afternoon of November 10 and later reported wind gusts from 70 to 75 knots.

The northwest winds were the worst possible situation for the Fitzgerald. The winds had a large fetch over open water allowing large waves to build. The Fitzgerald by this time was sailing southeast toward Whitefish Bay and passed over dangerous shallow water near Six Fathom Island.

At 3:30 p.m. on November 10 the captain of the Fitzgerald radioed the Anderson and reported that the ship was taking on water and listing. The Fitzgerald had also lost its radar, and was now relying on the Anderson to be its "eyes" in the storm. The first mate of the Anderson contacted the Fitzgerald at 7:10 p.m. and Caption McSorley of the Fitzgerald, when asked how they were doing, said "We are holding our own."  At 7:15 p.m. the Edmund Fitzgerald disappeared from the radar. 

On November 14 a Navy aircraft detected a large magnetic anomaly about 17 miles from Whitefish Point. A Coast Guard cutter located two large pieces of wreckage three days later using side scan sonar. In May 1976 a Navy controlled underwater recovery vehicle confirmed the wreckage was that of the Edmund Fitzgerald.

There are a number of theories on how the Fitzgerald sank. The initial theory was that the ship took on water through poorly sealed hatches, lost buoyancy, and sank when hit by huge waves. Another theory is that the ship may have been damaged in shallow water when it passed near Six Fathom Shoal. The debate continues to this day.

If you would like to read more about the Edmund Fitzgerald, check the following sources.

The Fateful Journey (The Great Lakes Shipwreck Museum)

NTSB Marine Accident Report: SS EDMUND FITZGERALD Sinking in Lake Superior  

Wednesday, November 7, 2012

A Winter Question for You

We are a little more than a week into November and there have already been many signs of winter in the U.S.  Although the winter solstice is still six weeks away (December 21st at 5:12 a.m. CST), meteorologists and many of us have our own "definition" of when winter starts. It's something I've personally been interested in for some time, and now I am working on a project that requires us to "define" winter. Your answers might help us shape some of this research

This question is open to all - those in warmer climates where winter is the season that isn't spring and summer, and those colder climates where winters can be brutal at times.

So, what defines the start of winter for you?

Post your responses here (preferred), or you can email me at would be very helpful if you would tell us what state you are from.  After a period of time I will compile the results and present them in a future blog post along with a scientific perspective on the seasons.  I think the results will be very interesting.

I look forward to hearing from you!

Tuesday, November 6, 2012

The Numbers on Sandy

From a meteorological standpoint Sandy was an impressive and historic storm.  Here are some of the more interesting statistics for this historic storm.

Near-record central pressure of 940 millibars (27.76 inches) when the center of the storm was about 35 miles off the New Jersey coast. This was the lowest pressure of any storm that has made landfall north of Cape Hatteras, NC. Hurricane Gladys in 1977 holds the record the for lowest pressure of 938 millibars (27.73 inches), a category 4 hurricane which never made landfall in the U.S.  At landfall Sandy's central pressure was 946 millibars. A number of locations set reord lower pressure readings. Atlantic City, NJ dropped to 948.3 millibars, breaking the old record of 961 millibars on March 6, 1932.

Winds gusted to in excess of 50 mph from Maine south through Virginia, but the strongest winds occurred from Washington DC north through New York City. Here are some of the locations that recorded hurricane force winds:

96 mph  Eaton’s Park,NY
90 mph  Islip, NY
90 mph  Chesapeake Bay Bridge, MD
89 mph  Surf City, NJ
88 mph  Montclair, NJ
88 mph  Tuckerton, NJ
87 mph  Newport, NJ
86 mph  Westerly, RI
85 mph  Madison, CT
83 mph  Cuttyhunk, MA
81 mph  Allentown, PA
79 mph  JFK International Airport, NY
79 mph  Thomas Point, MD
79 mph  Chester Gap, VA
76 mph  Laytonsville, MD
78 mph  Newark Int’l Airport, NJ
74 mph  LaGuardia Airport, NY

The combination of the hurricane-force onshore winds, the timing of high tide near Sandy's landfall, a full moon, and coastal topography resulted in destructive storm surge from Virginia to Rhode Island. The storm surge along the Virginia coast was 4 to 6 feet. Of course, as we know the worst surge was near and just north of Sandy's center in New Jersey and New York.

 Here are the most impressive and significant storm surges, measured as feet above normal average low tide:
  • 14.38 ft at Kings Point, NY
  • 13.88 ft at The Battery, Lower Manhattan. This broke the old record of 10.02 feet reached during Hurricane Donna in 1960.
  • 13.31 ft at Sandy Hook, NJ

RAINFALL from 10/28 to 11/1

There were more than 320  daily precipitation records set October 29-31 as a result of Sandy. You can find record values at the National Climatic Data Center web site U.S. Records page.

New Jersey
An impressive 237 New Jersey CoCoRaHS observers reported rainfall during this five-day period. The highest amount report was 12.71 inches at Stone Harbor 1.6 NNW in Cape May County, with 9.73 inches of that total on October 30. Other CoCoRaHS observers in Cape May County had 11.91 inches (Wildwood Crest 0.6 NNE); 11.70 inches (Wildwood Crest 0.1 WSW); and 11.41 inches (Middle Twp 4.4 SW). Other totals from Cape May County were generally greater than 7 inches.

CoCoRaHS observers reported period totals ranging from five to ten inches in eastern Virginia. The highest amount reported was 9.83 inches at Cashville .01 S in Accomack County, VA. This total is likely higher, as there were no reports after the morning of October 30.  The heaviest amounts in Virginia were in a corridor from Newport News and Virginia Beach northward and generally ranged from six to nine inches.

Amounts reported by CoCoRaHS observers in Maryland ranged from five to almost 11 inches. Here are the amounts greater than ten inches:

10.85     Easton 2.4 SE     Talbot County
10.70     Greensboro 1.4 ENE   Caroline County
10.68     Ridgely 0.2 ESE    Caroline County
10.29     Queenstown 2.6 S    Queen Anne's County
10.22     Easton 1.2 SSW    Talbot County

District of Columbia
The CoCoRaHS observer at Washington 5.1 NW (DC) reported 6.03 inches of rain.

Rainfall in Delaware ranged from five to ten inches. The highest CoCoRaHS amount reported there was 9.88 inches at Dover 6.4 WNW (Kent County). There were a number of stations reporting over seven and eight inches.

Eastern Pennsylvania also received heavy rain from this system with amounts ranging from three to eight inches. The observer at French Creek 3.4 SE (Chester County) measured 8.19 inches of rain during the period, and the observer at Schellsburg 2.6 WNW (Bedford County) reported 7.94 inches.
The heaviest precipitation amounts in West Virginia were in the higher elevations that also received snow and ranged from four to more than six inches. The highest precipitation amount for the period was 6.84 inches, along with 9.0 inches of snow at     French Creek 3.4 SE in Upshur County.

New York, Connecticut, and north

One to four inches of rain were reported in New York, two inches in Connecticut, one to three inches in Rhode Island, one half to 4.5 inches in Massachusetts, one half to 2.5 inches in Vermont, generally one to five inches in New Hampshire, but with 8.45 inches at Gorham 3.1 S and 6.23 inches at Randolph 1.4 NE, both in Coos County. One half to 3.5 inches of rain fell across Maine.

The rain from Sandy extended as far west as Ohio and Indiana. Four to more than seven inches of rain fell in eastern Ohio, with the heaviest and lake-enhanced amounts in Lake, Cuyahoga, and  Lorain Counties which border the southern shore of Lake Erie. More than six inches of rain were measured in these counties, with 7.68 inches at Painesville 3.8 SSW in Lake County and 7.54 inches by the observer at Mayfield 0.2 NW in Cuyahoga County.

72-hour snowfall ending October 31, 2012
Snow fell in southwestern Pennsylvania, much of West Virginia, western Maryland, western and southwest Virginia, southeastern Ohio, western North Caorina, and eastern Tennessee.  The heavy, wet snow brought down trees and power lines. Some of the highest snowfall totals were:

Richwood, WV  36"
Mount LeConte, TN:  34"
Snowshoe, WV  32"
Quinwood, WV 29"
Frostburg, MD 28"

Of course, the book hasn't closed on Sandy. At its peak 8.5 million customers in the eastern U.S. were without power. As of tonight  there are still 1 million without power, and the impending storm tomorrow will likely slow the restoration of power and may cause additional outages.

Sadly, Sandy has been responsible for 170 deaths with 111 of those in the U.S., 2 in Canada, and 57 Carribean.

Friday, November 2, 2012

A Tip of the Hat to the NWS

One aspect of "superstorm" Sandy that is receiving little attention is the role of the National Hurricane Center and the National Weather Services offices throughout the east. The accurate forecast of the storm track and the days of warning about the expected impact of this storm without question saved many lives. In the coverage of the aftermath - the astounding damage, the rescues, and the heroic stories, it's easy to lose sight of the fact that without the skill and dedication of these forecasters, the human toll could have been much, much worse. No one can say "We didn't know this was going to happen."

Improvements in computer models were intrumental in the accurate forecast of Sandy's track and intensity. However, models are far from perfect and it takes the knowledge and skill of a human forecaster to interpret the computer forecasts and make the final forecast and issue the appropriate warnings. Those models also require accurate data to initialize correctly. NWS offices across the U.S. launched two extra upper-air soundings each day for three days prior to Sandy's arrival to provide more up to date and accurate data for the models. Normally there are two soundings per day.

This graphic was prepared by the Huntsville, AL NWS office and shows
the forecast tracks for Sandy three and five days prior to landfall
Forecasters and staff in the individual National Weather Service offices from the Carolinas through Maine worked continuously to update the warnings and advisories that kept emergency officials and the public informed about the storm and its impacts. In the hardest hit areas staff worked while their families were home dealing with the storm. This is the case when severe weather is occurring anywhere, be it a hurricane slamming into New York or massive tornadoes swarming through the southeastern U.S. The NWS facilities aren't immune to the wrath of these storms, either.  At this time a cut fiber optic cable and other communications issues are affecting the web sites in the Eastern Region and they are operating in backup mode. The Eastern Region Headquarters is in Upton, NY.

A press release from the World Meteorological Organization also gave a thumb's up to the National Weather Service.

"WMO’s Director of Weather and Disaster Risk Reduction Services, Geoff Love, said there is virtually no difference between the analysis of likely events and the forecast.  He said the 48-hour forecast was spot-on.

“The environmental conditions were perfect. The forecasts were very, very, very good and, of course, we have seen on the media the U.S. emergency authorities all responded exceedingly well," said Love. "So, from the WMO perspective, it is a disaster. But, boy, all our systems worked really well - the U.S. forecast, the U.S. Emergency Management systems. And, it will be seen as, probably, a text-book case in how well you can do.”

So, a tip of the hat and pat on the back for a job well done to the men and women who monitor and forecast our weather for the purpose of protecting lives and property.