Woke up this morning to a chilly 35 degrees out on the WeatherDeck in Cockeysville. Started out the door with a light jacket, and my wife stopped me. "Is that going to be enough?" she asked me?

Now, you need to understand that she works for the Baltimore County schools, where they turn off the furnaces on April 15. The staff at her school has been freezing for two weeks. (Sorry. No pay raises, and no heat either for the folks who teach our kids.) She can't wear enough clothes to stay warm in the classroom. It took her all evening at home to warm up again. And our furnace kicked on last night.

But I digress. I stepped outside, and it was cold alright. But I kept the light jacket. The sun was bright and warm, and the air has warmed up quickly this morning. Downtown, at Calvert & Centre streets, the overnight low was only 47 degrees - about normal for this time of year.

Out at BWI, the thermometer slipped to 36 degrees this morning. But as chilly as that was, it was just shy of the record low for an April 30 at BWI, which was 32 degrees, set back in 1961, during the Kennedy Adminstration.

Here are some other overnight lows reported this morning from around the region:

Forecasters are looking for a high this afternoon around 60 degrees, about 10 degrees cooler than the longterm average.

Here's the good news. This month's Goldilocks weather has saved us a bundle in both heating and cooling expenses. The total of heating degree-days for April at BWI ran 25 percent below the longterm averages, meaning a 25 percent savings in consumption, all else being equal. And cooling degree-days were also very scarce, running 40 percent below the norm.

That silence from the furnace and the AC compressors is like the jingle of change in your pocket. Enjoy it.

Posted by Frank Roylance at 10:34 AM | Permalink | Comments (1)
                    

Rain over the last three days has brought the month's total to more than 4.6 inches at Baltimore-Washington International Thurgood Marshall Airport. That's more than 1.8 inches of surplus for the month through Monday, and brings the deficit since Jan. 1 down to less than an inch. 

Here are the monthly surpluses (+) and deficits (-):

Jan.: -2.00 inches

Feb.: +0.78 inch

March: -1.56 inches

April: +1.84 inches (through Monday)

The 4.6-inch total for April also makes this the wettest April since ... well, since last year, when we absorbed 5 inches of rain. Normal for a complete April at BWI is 3 inches, but we've topped 4 inches of rain in April only seven times since 1980.

Here are some rain measurements for yesterday from around the region.

Maryland streamflow is abundant for the time being. Here's the realtime flow map. And groundwater reserves continue to rise.

Here's the chart for that monitoring well out in Granite, Baltimore County, we like to track. Looks like their gear failed Sunday just as the latest rains began. But it's up about 4 inches since April 1.

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Posted by Frank Roylance at 4:50 PM | Permalink | Comments (0)
                    

It should begin to feel a little less like Ireland today. The clouds you see on top of us in the satellite image should begin to erode, the sun should reappear and the dank air will begin to dry out this afternoon. The cold front is past us now, and high pressure is building in.

The clearing skies, of course, will increase radiational cooling after dark tonight. That could mean some patchy frost west of the I-95 corridor. The forecast lows show 37 degrees at BWI, 36 at Westminster and 35 at Hagerstown. That's plenty cold enough for frost.

Wednesday may be our only truly sunny day this week. But it will be chilly. They're calling for highs of only 60 degrees tomorrow at BWI. That's almost 10 degrees below normal for this time of year. There will be clouds around Thursday and Friday, too, but we should see some sunshine as well. For those of us longing for some toasty weather amid all this Irish mist, Friday will be the warmest day of the week, reaching only 74 degrees.

Then, it looks like yet another damp weekend, with showers returning late Friday and lingering through Sunday as a new low out of the northern Plains states drags the next cold front through the region. Slainte!

Posted by Frank Roylance at 10:51 AM | Permalink | Comments (1)
                    

Rainfall yesterday and today has done a good job of knocking down last week's sky-high pollen counts. Unfortunately, it has also put an end to the spring blossoms we've enjoyed in recent weeks.

For some, like this driver this morning on Harford Road, it also offers an unexpected decoration for the old gray ride. The picture was taken by Kurt Kocher, spokesman for the city's Department of Public Works. Thanks, Kurt!

Posted by Frank Roylance at 4:31 PM | Permalink | Comments (0)
                    

I need to start working weekends, and taking the middle of the week off. Maybe you've noticed. Most of our rain this month has fallen on or around the weekends, while the workweek has remained mostly sunny.

It's uncanny. And worse - the forecast for this week is shaping up along much the same lines. Rainy today and early tomorrow, then clearing for mid-week, and clouding up for more rain this weekend. Who wrote this script?

You can look it up:

* Fri-Sun, April 11-13:  0.18 inch rain

* Mon-Fri, April 14-18: Trace

* Sat-Mon, April 19-21: 1.97 inches rain

* Tues- Fri, April 22-25: no rain

* Sat-Sun, April 26-27: 0.49 inch rain

There may be some science behind the idea, too. In summer at least, there's evidence that human activity - particulate air pollution, which peaks during the workweek - can cause weekly cycles in rainfall in the southeastern U.S. Here's more.

And there's plenty more rain expected today. Showers and thunderstorms are likely after 2 p.m. this afternoon, perhaps extending into Tuesday morning as low-pressure pulls cool, damp air in off the ocean today, and drags a cold front across the area tonight.

Then things start to dry out for the middle of the week. The sun should be out by tomorrow afternoon. Clear skies by Tuesday night could produce lows in the 30s, and a patchy late frost by Wednesday morning west of the I-95 corridor.

The sunshine should persist through the rest of the week, with daytime highs crowding 80 degrees again by Friday (sounds just like last week, doesn't it?) But then clouds and moisture and showers move back into the region - you guessed it - for the weekend.

The good news, of course, is that we are gradually making up the rainfall deficit that had been accumulating since last May.

Since Jan. 1, BWI has recorded 11.38 inches of precipitation. That's less than 2 inches below the long-term average for the period, and we're likely to erase a good bit of that shortfall before the rain ends tomorrow morning.

And, while it may not have seemed like it late Saturday afternoon (as the north wind turned cold and dropped temperatures here at Calvert & Centre streets from nearly 80 degrees at 4 p.m., to just 65 degrees by 7:30 p.m.), April has been unusually mild - the 6th warmest April at BWI in the past 30 years, averaging 56.2 degrees. 

One more day of this cool, dank, marine weather, though, and maybe April won't be quite such a standout.

Posted by Frank Roylance at 10:37 AM | Permalink | Comments (0)
                    

Yet another crowd of tropical weather forecasters has chimed in with their predictions for the upcoming Atlantic hurricane season. Two weeks ago it was the Colorado State University team of Phil Klotzbach and William Gray, calling for a "well-above average" season.

Now it's AccuWeather.com's hurricane trackers, led by Joe Bastardi, who's expecting only "slightly more storms than average," with increased risk of U.S. landfalls, during the six-month season that opens, officially, on June 1.

For the record, "average" in the Atlantic basin during the period from 1950 to 2000, means 9.6 named storms, with 5.9 of those growing to hurricane force, and 2.3 of those, on average, reaching Category 3, with sustained winds of 111 mph or more.

Bastardi and his crew say both the waning La Nina conditions in the tropical Pacific Ocean, and a continuing warm-water cycle in the Atlantic argue for slightly more activity than the average, and increase the chances for U.S. landfalls.

More specifically, they note that the warm conditions are not uniform across the basin. "In some areas where hurricanes normally form - the central and eastern tropical Atlantic," Bastardi said, "ocean water temperatures are near or below normal. This should limit the number of storms." So don't expect a blowout season like 2005.

But "the warmest waters relative to normal will be in the northern areas of the Atlantic, especially toward the North American continent. This could potentially increase the threat of major landfalls to the U.S. coast."

Where the spread of storm tracks last year shifted southwest, sending a batch of powerful storms across the northern Caribbean, "this year, early indications show that the spread will move north and east, with a target closer to the Southeast U.S."

In their April 9 forecast, Klotzbach and Gray said there would be a 45 percent chance that a Cat. 3 storm or bigger would make landfall somewhere along the east coast, including Florida. The long-term average for the last century is 31 percent per season.

Bastardi and company say the conditions this year most resemble those in 1955, 1996 and 1999. (Klotzbach and Gray agreed on 1999, but also found analogs in 1950, 1989 and 2000.) NOTE: An earlier version of this post, relying on a release from AccuWeather included inaccurate dates. AccuWeather has since corrected its release, and those fixes are reflected here.)

In 1955, Hurricanes Connie and Diane struck North Carolina. And 1999 saw both Hurricanes Floyd and Dennis strike North Carolina. Here's the storm track for Floyd.

Hurricane season forecasting is, of course, a very young science. Weather and climate are vast, chaotic systems with more variables than even the most advanced computer models can capture with any certainty. These forecasters do their best with the knowledge they have (or think they have). And their efforts get lots of news play because hurricanes are big threats to life and property. There is always some benefit to alerting the public to the risks we face every year, in the hope we will pay attention, and prepare, when storms are on the move.

When seasonal forecasts fall short of perfect, as they have in recent years, there's a risk that the public will scoff and pay less attention to the hazard in the future. That would be a mistake. Even a slow storm season can cough up one or two calamitous storms. See Hurricane Andrew in 1992. That's some of Andrew's aftermath at left.

Next up is the National Oceanic and Atmospheric Administration's forecast, due out next month.

Posted by Frank Roylance at 10:48 AM | Permalink | Comments (0)
                    

Imagine a 6 by 6 oak post, sunk three feet into the earth as a support for an outbuilding. Now imagine wind strong enough to suck it up out of the ground like a golf tee and toss it the length of four football fields. That's what the NWS surveyors found in Virginia where one of Sunday's three tornadoes struck. And that was only an EF-0 twister. Here's more on the Enhanced Fujita scale of tornado intensity.

The initial reports from the NWS Sterling forecast office are now available online. Click here. For the specifics on the Maryland damage, click here. For the Virginia details, click here.

There's also this nifty map of rainfall reports from the precip on Sunday and Monday.  It's a bit disorienting, covering just the Sterling office's forecast area. That's the Western Shore of the bay on the right, with Harford County at upper right, St. Mary's at lower right. The Pennsylvania line runs across the top, as far as Allegany County. (Garrett is covered by the Pittsburgh office.) The bulk of the map covers Northern Virginia.

Posted by Frank Roylance at 5:39 PM | Permalink | Comments (0)
                    

The new Drought Monitor map is in this morning. As expected, it shows the recent rainfall (and there's more to come) has shrunk the region of the state that's still experiencing moderate drought conditions (tan on the map), from 27 percent to 22 percent.

Meanwhile, the region that is rated "abnormally dry" (yellow plus tan) has diminished from 51 percent to 36 percent. The portion of the state enjoying normal soil moisture and streamflow (white on the map) - including Baltimore and its suburbs - has jumped from 49 percent last week, to 63 percent this week. 

Streamflow looks better across most of the state, too. And the forecast promises more moisture this weekend, into Monday. Bad news for outdoor plans, but good news for gardens, crops, reservoirs and water tables. Here's a 30-day chart for a USGS monitoring well in Granite, Baltimore County.

Posted by Frank Roylance at 10:10 AM | Permalink | Comments (0)
                    

                                                                             Sun photo by Nanine Hartzenbusch 2003 

We're headed for the 70s today, with plenty of sunshine getting through amid increasing cumulous clouds. You can thank warm, moist air flowing up from the south and west.

But enjoy the next couple of days because forecasters see a series of cold fronts in our future, bringing chances for showers this weekend, and by next week a "soaking rain" before this balmy springtime weather returns.

But the work week (wouldn't you know) looks sunny and mild, with temperatures crowding 80 degrees by Friday. Plan your lunches for a sidewalk cafe somewhere, because you won't be eating al fresco this weekend.

They're calling for highs in the 60s and afternoon showers on Saturday as a high-pressure center over New England shoves what meteorologists call a "backdoor" cold front our way off the water. That happens when the clockwise circulation around the high to our north and east sweeps eastward around the high, bringing cool, wet air in off the Atlantic. This one's not too strong, so any precip will be isolated or scattered.

But there's another, stronger cold front approaching from the Great Lakes by late Saturday, increasing our shot for some showers on Sunday. And yet another cold front due here by Monday has plenty of moisture and forecasters are saying it "has the potential to bring a soaking rain to the region" early next week. The precise timing is a little vague at this point. But you'll likely need an umbrella at the bus stop next week.

There are still cooler conditions - highs in the 50s - and more puddles ahead later on next week. April showers, indeed.

Posted by Frank Roylance at 10:57 AM | Permalink | Comments (0)
                    

                                                                                                    Credit: CoCoRaHS 

Do you love weather? Do you like to work with numbers and weather instruments? Perhaps you'd like to become a volunteer weather observer in Northern Maryland for the Community Collaborative Rain, Snow and Hail Network (CoCoRaHS). 

Bruce Sullivan is reaching out to the WeatherBlog in the hope that our readers might include folks who would be interested in joining the CoCoRaHS team in this area. You would be contributing to the gathering of data such as these.

The group is organizing another training and information session for would-be observers, this coming Tuesday at 3 p.m., at the U.S. Geological Survey office near the University of Maryland Baltimore County. The address is USGS, MD-DE-DC Water Sciences Center, 5522 Research Park Drive, Baltimore, MD, 21228.

(An earlier version of this post listed a 4 p.m. start time. That is incorrect. Session begins at 3 p.m.)

You can also email Bruce at bruce.sullivan@cocorahs.org

Finally, you can read more about the organization here. And here.

Posted by Frank Roylance at 2:35 PM | Permalink | Comments (0)
                    

Monday was the rainiest day at BWI-Marshall Airport since Feb. 1, and the improving precipitation picture is having the desired effect on the Baltimore region's reservoir system.

Rainfall over the past two days at BWI totaled 1.97 inches. That pushed the month's total to 3.25 inches, which is a quarter-inch wetter than the average April for the period 1971-2000. Monday's total was 1.32 inches. That was not quite a record for the date. Baltimore received 1.41 inches on April 21, 1918. 

Streamflow across the state is back in normal ranges, for now. But we remain in deficit for the calendar year-to-date, by about 2.5 inches.

The city's Department of Public Works reports the reservoir system is currently at more than 88 percent of its capacity, with more than 75 billion gallons in storage. That's up from 64 percent back in December, when authorities decided the continuing drought made it prudent to tap the Susquehanna River as a way to preserve supplies in the reservoirs.

Liberty Reservoir currently stands at 87 percent of capacity, up from 82 percent last month. Prettyboy is at 86 percent, up from 75 percent last month. Loch Raven stands at nearly 98 percent, up from 95 percent in March.

The new Drought Monitor map is being calculated today, and will be released Thursday morning. Here's how one of the city's reservoirs looked last fall.

  Sun photo by Jed Kirschbaum

Posted by Frank Roylance at 12:18 PM | Permalink | Comments (0)
                    

Those were some impressive showers yesterday. We totaled 1.8 inches here on the WeatherDeck in Cockeysville, with more rain due today as this low to our south keeps pumping wet air in off the Atlantic.

Down at BWI-Marshall they clocked just 0.65 inch by midnight last night, but other areas saw far more. Here is an accumulation map from the CoCoRaHS observers, with some observations topping 2 inches.

One report out of Sabillasville, in Frederick County exceeded 4 inches.

Here's a NWS accounting of some of the storm and damage reports yesterday, including several tornado sightings in Southern Maryland.

The forecast is another wet one, with more heavy showers likely today, wet again tomorrow, with the sun finally reappearing on Wednesday. The continued southerly flow off the ocean will bring a risk of minor coastal flooding at high tides today. Here's the list of advisories.

And I will be out in it today. My car quit on me. "Busted flat in Cockeysville, waitin' for a tow. Feelin' near as faded as my jeans ..."

Posted by Frank Roylance at 7:58 AM | Permalink | Comments (0)
                    

This morning's Mag. 5.4 earthquake in Illinois occurred in an area with a history of small tremors - and some big ones - going back to the early 1800s.

Here's a link to the U.S. Geological Survey report on today's quake. And here's one to a description of the local geology and the history of tremors in the region.

Although we don't think of the middle of the country as being earthquake-prone, there have been some very powerful quakes in the region, centered mostly on the New Madrid, Mo., area. Historical accounts of New Madrid quakes in the early 19th century are quite astonishing. They were felt as far away as New England.

Here's what the USGS says about the area: "Moderately damaging earthquakes strike somewhere in the region each decade or two, and smaller earthquakes are felt about once or twice a year. In addition, geologists have found evidence of eight or more prehistoric earthquakes over the last 25,000 years that were much larger than any observed historically in the region."

Emergency managers in Memphis and other communities in the area have recently begun to take the threat very seriously, and there has been a great deal of planning, and quake-proofing work in recent years to protect key Mississippi River crossings and gas and oil pipelines.

Posted by Frank Roylance at 8:35 AM | Permalink | Comments (2)
                    

Long-range forecasters have a new prediction for this summer, just out this week. It's HOT.

The forecast for the June through August period says the probabilities point toward above-average temperatures for the northeastern United States. The same holds for the Western states and for Southern Florida. The map's below. Until recently, the forecast showed no clear trends on temperatures for our region. Now it does.

The same forecasters found no clear trends, however, on precipitation for the summer in these parts. The only strong trends seem to be in the Northwest states, which face dry conditions for the summer.

Posted by Frank Roylance at 8:24 AM | Permalink | Comments (1)
                    

The National Oceanic and Atmospheric Administration says March 2007 was the second-warmest on record globally, but cooler than the long-term average for the contiguous 48 states. In fact, the Western snowpack is the healthiest  in more than a decade, thanks to heavy snowfall in December, January and February.

Here's the full report.

And here are some highlights:

* Temperatures in the lower 48 states averaged 42 degrees in March, almost a half-degree lower than the average for the past 113 years.

* Alaska had its 17th-warmest March, 3.8 degrees above the mean from 1971-2000.

* Globally, land and surface water temperatures averaged 1.28 degrees above the 20th century mean, making it the second-warmest March globally. The average was pushed higher by much-warmer-than-normal temperatures in Eurasia.

* While the Western snowpack fared well in March, snow cover across the Northern Hemisphere was the fourth-lowest on record, consistent with the pattern of the past two decades, in which warming temperatures reduced the northern snow cover.

Extreme events during March included a rare downtown tornado in Atlanta, heavy rains in Missouri, widespread flooding from the Ozarks to Indiana, heavy snows in Kentucky and Ohio.

Here's a NOAA map of some other extreme March events around the world:

Posted by Frank Roylance at 3:20 PM | Permalink | Comments (0)
                    

One reason we're enjoying this beautiful stretch of dry, sunny weather along the East Coast is that the high-pressure system that's generating our delightful conditions is being held in place by a deep low off the coast, to our east.

From space, the big storm can be seen clearly as it spins in this satellite loop, counter-clockwise, almost like a hurricane. It's also churning up the ocean, and sending strong surf ashore along the Carolina coast, where high surf advisories are up.

The storm is slowly moving off to the northeast, and our fine weather will begin to deteriorate late Saturday as the next low moves our way, with rain due on Sunday and Monday. Sorry.

Posted by Frank Roylance at 2:47 PM | Permalink | Comments (0)
                    

Fifty years ago, in 1958, Flagstaff passed the nation's first lighting ordinance designed to protect the night sky from the ravages of "light pollution." In truth, it was an effort to protect the view into space from the neaby Lowell Observatory. The pioneering work in Flagstaff has subsequently preserved the riches of the night sky for a growing list of observatories situated in the nearby mountains, and thereby encouraged the growth of an important local industry.

This photo shows in a very dramatic way (aided by both a truly light-pollution-free sky and a time exposure) just how glorious the night sky over Flagstaff can be now that outdoor lighting has been shielded - so that it points down, where it's needed, instead of up at the bellies of passing birds. It also happens to save energy and money, since you don't need as much candlepower if you're not sending light where it's not needed.

Here in Baltimore (below), and in most other cities, we delight in urban lighting programs that illuminate our buildings from below, with most of the glare shining up into the sky and erasing the stars ! When was the last time YOU saw the Milky Way?

You can learn more about outdoor lighting ordinances, from the International Dark Sky Association.

The Flagstaff image, credited to Dan and Cindy Durisco, the US. Naval Observatory, the Lowell Observatory and the Flagstaff Dark Skies Coalition, shows the San Fransisco Peaks beneath the Milky Way and a stationary "lenticular cloud," formed as moist air flows up and over a mountain range, condensing as it cools. Here's an amazing gallery of lenticular clouds.

Credit: The Sun, Thomas Graves, 1998

Posted by Frank Roylance at 10:17 AM | Permalink | Comments (2)
                    

That's what the folks out in Sterling are calling it - fine "autumn" weather. Clear, dry air beneath a big fat high-pressure system is bringing us sunny days and clear, starry, frosty nights this week. And we can expect it to continue into Saturday before a new low from the east begins to cloud things up and threaten some showers by Sunday.

In the meantime, we're beginning to catch the return, clockwise flow around this high. That will scoop warmer air from the Southeast and send it our way, raising daytime highs to the mid- to upper-70s Thursday and Friday. Getting married Saturday? The good weather should hold long enough to keep things pretty for you and your guests, though clouds will be moving in later in the day. The rain, at least, should hold off.

Nighttime lows will moderate, too. After several frosty mornings this week in the 30s, and even some 20s to the north and west of the urban corridor, we will see the last of the 30s tonight, with overnight lows in the 40s and 50s for later in the week.

One interesting phenomenon to watch in the next two days will be the Chesapeake bay breeze. As the land heats up under strong April sunshine, the air above it will warm, too, and start to rise. As it does, cooler air over the water will be drawn in to replace it. That will hold temperatures down along the Western Shore, in places like Annapolis and Baltimore, while inland communities like Westminster heat up. A similar setup will likely keep the beaches under onshore breezes, keeping them quite cool relative to inland Eastern Shore towns. 

Posted by Frank Roylance at 4:38 PM | Permalink | Comments (0)
                    

Dennis Barnes is setting up a beautiful instrument in his garden in Abingdon. It's called an armillary Galileo sundial. He wrote to me yesterday because he is preparing to "set" the sundial today, taking advantage of the fact that today - April 15 - is one of only four days on the annual calendar when solar noon - the moment when the sun is highest overhead - is the same as noon according to "mean solar time," or clock time.

To astronomers, it's the day when the "equation of time" equals zero. At other times of the year, the sun can be as much as 14 minutes "fast" or 16 minutes "slow" relative to clock time.

But of course this is astronomy, so nothing is as simple as we'd like.

Here's Dennis's problem: First, the equation of time (the difference between mean sun time and clock time) is only zero today along the "standard meridian" in each time zone. For us here in Eastern Time, that's 75 degrees west longitude, which runs north and south just off the beaches at Ocean City. So, all of Maryland is actually west of the standard meridian. Solar noon reaches us late as the sun moves across the sky from east to west.

Sti