The photo shot yesterday by NASA's Terra Earth Observing satellite shows just how brilliantly clear skies were yesterday over the Northeast. (Wish they skip superimposing the state borders every now and then, and let us see it the way astronauts do!) Here's a closer look.

But high clouds will start to slip in later today as the next cold front and low-pressure system begin to approach from the Great Lakes by early Saturday.

That system will draw warm, moist air up from the Gulf of Mexico, and bring it into collision with the cool air from the north and west, triggering areas of fog tonight and showers and thunderstorms by Saturday afternoon. Chance of precip tomorrow is 70 percent, slipping to 40 percent Saturday night.

Rain amounts are forecast to stick between a tenth- and a quarter-inch - not enough to push this May into the record books for total rainfall. Only a cloudburst over BWI would make up the inch-plus needed to break the 1989 record. But second-best is still pretty impressive:

May 1989: 8.71 inches

May 2008*: 7.52 inches

May 1894: 7.26 inches

May 1960:  7.10 inches

May 1886:  7.07 inches   

* Through 5/29

National Weather Service

Sunday looks sunny, as do Monday and Tuesday. More showers are expected by mid-week.

Image courtesy of the Space Science and Engineering Center, Univ. of Wisconsin

Posted by Frank Roylance at 10:52 AM | Permalink | Comments (0)
                    

The weather station aboard the NASA Mars Phoenix lander is up and running. Here's the NASA report on today's conditions:

"The weather at the Phoenix landing site on the second day following landing was sunny with moderate dust, with a high of minus 30 degrees Celsius (minus 22 degrees Fahrenheit) and a low of minus 80 (minus 112 degrees Fahrenheit)."

And we want to go there, why?

Here's more from the Canadians who built the station. And here's their weather page.

Posted by Frank Roylance at 6:17 PM | Permalink | Comments (3)
                    

Okay, so it will never rival the National Weather Service, or even the BWI data available in the Almanac section of MarylandWeather.com.

But our data archive here at The Sun's little Davis Vantage Pro 2 weather station (like the one at left) is slowly expanding. We have today managed to upload measurements taken between Jan. 1, 2008 and the present, which you can access here.

Next, we plan to upload all the readings we've gathered since the station was established at Calvert & Centre streets, WAY back on Sept. 6, 2006. It's a slow process. It takes about a minute for each day of data, so we will likely have to leave the computer running overnight.

The kink in the system is that, while we're uploading, we can't post current data. That means once the old numbers are moved, we have to go back and recover the readings that we couldn't upload in real time. Then we have to upload those, which means more current data is delayed.  Arrrgghh!

So be patient with us. We're working on it.

In the meantime, if you need to know the barometric pressure at 3:10 p.m. on Feb. 16, 2008 (it was 30.31 inches), or for any other 10-minute interval since Jan. 1, you can look it up here for free. 

The Sun station data has been accessed more than 2,800 times already. Is this Weather Geek Heaven, or what?  

Posted by Frank Roylance at 5:11 PM | Permalink | Comments (0)
                    

In case there's still a soul out there who hasn't already figured this out, the drought of 2007-08 in Maryland is finished. Washed out. In fact, there's not an acre in the state that remains even "abnormally dry" according to the latest Drought Monitor map, out this morning.

The nearest spot with soil moisture, streamflow, rainfall or foliage health that still registers as "dry" is a speck of territory in the far southern end of West Virginia. Beyond that, moderate to extreme drought persists in the western counties of the Carolinas. But even that has moderated some in recent weeks.

We've gone from no drought at all on June 19, 2007, to a high of 87 percent of the state back on Oct. 9. Conditions began to improve in December, but even as recently as March 4, nearly half the state (47 percent) was still reporting drought conditions. But ample rains since dropped that percentage to zero by mid-May. Here are the details. 

We can thank an extraordinarily wet May - the second-wettest on record here since they began keeping track in 1871. There's more rain in the forecast for Saturday, so we may yet challenge the record of 8.71 inches, set back in 1989.

Anyway, here's a nifty animation of the drought as it waned during 2008. You can watch the 2007 animation by clicking here.

Posted by Frank Roylance at 10:55 AM | Permalink | Comments (2)
                    

I don't think we need to write much about the weather forecast for the next few days. Nothing but warm, sunshiney days and starry nights, from what I can see. Saturday's another story.

Forecasters out at Sterling say they're looking at another cold front moving through for the weekend, and it looks stronger than the one that moved through with a few thundershowers last night. That is raising the spectre of severe storms, with the chance for lightning, hail and damaging winds. They're putting the precip chances at 50 percent. No handicapping on the "severe" part yet.

A heavy storm over BWI could send Baltimore's rainfall totals for the month over the May record of 8.71 inches, set in 1989. We're at 7.52 inches today. It will be a stretch, but it's not inconceivable. (The May average at BWI is 3.89 inches.) 

This is already the second-wettest May here since record-keeping began in 1871.

More showers are in the forecast for Sunday, June 1. But the chances are smaller at 30 percent. That figures. Saturday is my only day off this weekend. Gotta work on Sunday.

That's Sun photog Karl Merton Ferron's photo above, shot downtown in July 2007.

Posted by Frank Roylance at 11:51 AM | Permalink | Comments (0)
                    

Say what you want about today's gray skies and threat of rain. But at least it had the decency to hold off until after we enjoyed a perfect Memorial Day weekend. The satellite photo above shows the clouds that have moved down over us from the Great Lakes.

The high yesterday at BWI Marshall was 85 degrees, with strong sunshine. Hard to imagine a nicer day. That was 8 degrees warmer than the long-term average (77) for the date at BWI. The record is 94 degrees, set back in 1914.

Forecasters say we could go even higher this afternoon, reaching 88 degrees at the airport as warm air continues to move in from the south and west ahead of an approaching cold front.

The clash of warm air and cold air along that front brings with it a 60 percent chance for rain, with a risk of thunderstorms in the late afternoon and early evening. Some could be severe along the Chesapeake Bay and in the Baltimore and Annapolis region, forecasters say. If we get one, watch for damaging winds and large hail. Here's the Northeast radar loop.

Behind the front, we can expect sharply cooler temperatures, with strong north winds dropping temperatures into the low 50s tonight, and maybe the upper 40s in the normally cooler spots. Tomorrow will look much different than today, with clear, sunny skies returning, and a high around 70 degrees. That's cooler than last night's low of 74 degrees here at Calvert & Centre streets.

That's good news. It was starting to get uncomfortably warm and humid in the house late yesterday. I was tempted to turn on the AC. But I resisted. We've been enjoying the cool weather this month, and with no need to heat or cool the place, our BGE bill was the lowest of the year so far.  We've had just 12 cooling degree-days so far this month, well below the long-term average of 50 for this time of year at BWI. If only this could continue...

The sunshine should stick around for the rest of the work-week as high pressure builds back into the region. Daytime temperatures will gradually warm back into the 80s until the next frontal system brings showers and thunderstorms for the weekend, forecasters say.

Posted by Frank Roylance at 10:45 AM | Permalink | Comments (2)
                    

A huge tornado (not the one pictured here) struck near Fort Collins, Colo. today, and was captured on video by a local TV crew as it blackened the sky and pelted the camera operator with hailstones. 

Meanwhile, a fledgling storm-chasing organization in Hungary managed to film a tornado there as it formed on May 20 - a comparative rarity in Europe. Click here for that one.

Posted by Frank Roylance at 3:14 PM | Permalink | Comments (1)
                    

                                                       A chilly Ocean City in May 2007 - Sun photo by Glenn Fawcett 

Many neighborhood swimming pools will be opening up for the season this weekend. And a few brave souls may be ready to take a plunge into the Chesapeake or the Atlantic as the Memorial Day holiday marks the unofficial start of summer in Maryland.

But it's going to be a breath-taking experience. Here's how Andy Woodcock - a National Weather Service forecaster out at Sterling, put it in this morning's forecast discussion:

"FUNNY THING...WHEN I WOKE UP THIS MORNING THE FIRST THING I THOUGHT
OF WAS "COMMUNITY SWIMMING POOLS WILL BE DOWNRIGHT COLD THIS
WEEKEND." NO IDEA WHY I THOUGHT THAT...BUT CERTAINLY TRUE. WEATHER LOOKS TO
BE QUITE NICE FOR THE MEMORIAL DAY WEEKEND...BUT W/ OVERNIGHT LOWS STILL IN
40S...AND PLENTY OF COLD RAINFALL DURING THE PAST FEW WEEKS...THAT WATER WILL
BE CHILLY. THOMAS POINT LIGHT WATER ONLY 60. BRR."

Well, our low overnight here at Calvert & Centre streets was 52 degrees, but out at the airport they reported a low of 45 degrees - almost 10 degrees below the long-term average for this time of year. The forecast for tonight puts the BWI low at 47 degrees, creeping to 49 Friday night and 51 by Saturday night.

Daytime highs are running about 5 degrees too cool for this time of year. But the forecast has them rising to  the mid-80s by Memorial Day. If you're headed for the beaches, however, don't expect to see temperatures that warm. Here's OC's forecast.

As for water temperatures,  Ocean City is reporting 58-degree water at the Inlet. The readings are 60 degrees at Annapolis and Tolchester. A defibrillator is advised.

As for the pools, well, I'd advise alerting the lifeguards before you dive in.

Posted by Frank Roylance at 11:49 AM | Permalink | Comments (0)
                    

Marylanders should have a decent and improving chance to see the International Space Station Thursday and Saturday evenings as skies begin to clear up in the wake of the latest round of May rain showers. Grab the kids, the neighbors, the neighbors' kids, and amaze them all with your knowledge of the night sky.

The first good opportunity will come Thursday evening as the ISS makes its way along an orbit taking it about 240 miles over New Orleans, Baltimore and Nova Scotia. The forecast here calls for partly cloudy skies. But the station will be reflecting plenty of sunlight, and should be bright enough to spot, even if you have to catch it between the clouds, or through thin clouds, or amid urban light pollution.

Watch for a bright, star-like object rising above the southwestern horizon at 9:30 p.m. If it's blinking, or sports colored or multiple lights it's an airplane. Keep looking. Skipping along at 17,500 mph, the ISS will climb past the closely-paired planet Saturn and bright star Regulus, in the constellation Leo. It will rise 75 degrees above the northwestern horizon at its highest by 9:32 p.m.. That's almost directly overhead as seen from Baltimore.

From there the station and its crew will pass directly "through" the stars of the Big Dipper, and head off toward the Northeast, disappearing at 9:35 p.m.

Saturday's flyby will follow a very closely parallel orbit, tracking north and east up the East Coast of the United States.

The forecast is better than Thursday's. Watch for it rising again above the southwestern horizon - this time at 8:39 p.m. It will pass midway between Saturn and Mars and zip once again through the stars of the Big Dipper at about 8:43 p.m. Then it will fly off toward the northeast, disappearing at 8:45 p.m.

You can get your own ISS predictions - and more - from Heavens-Above.com  They're customized for your location. The Heavens Above sky map here shows the ISS's Thursday path across the sky as seen from Baltimore.

Remember to stop back here after the show and share the experience with those who just don't GET it.

Shuttle astronauts are preparing for another visit to the station, with launch of the shuttle Discovery set for May 31 - next Saturday.

Posted by Frank Roylance at 10:58 AM | Permalink | Comments (3)
                    

Another chilly day for Central Maryland today as the high at BWI stalled  at the 56-degree mark. That is 20 degrees below the normal highs for a May 20 in Baltimore, and just three degrees above the all-time low maximum temperature for a May 20 in Baltimore - 53 degrees, set on this date in 1994.

The high here at Calvert & Centre streets managed to climb all the way to 57 degrees after the sun came out.

Back on May 12 the high at BWI was just 50 degrees, and that did set a record for the date, breaking the 126-year-old record of 51 degrees, set in Baltimore WAY back, on May 12, 1882.

They're calling for a low tonight in the 40s. It's great we haven't had to run the AC yet this year. But we sure did have to throw another blanket on the bed last night. The low at BWI this morning was 44 degrees, just five degrees warmer than the all-time record low for the date - 39 degrees, set in 2002.

So far, we're running almost 2 degrees cooler than normal for the month. Rain is way ahead. We're at 7.52 inches so far through today, making this the second-wettest May on record for Baltimore. The record is 8.71 inches, set in May 1989.  May rainfall has topped 7 inches only three other times:

1894:  7.26 inches

1960:  7.10 inches

1886:  7.07 inches

But warmer, drier days are coming. The new forecast from Sterling says the highs this weekend will stretch into the 70s, and to the 80s in time for Memorial Day. That's - well above the mark predicted in earlier forecasts. 

 Freckles seeks shelter from light rain during Memorial Day observances in Timonium in 2004. Sun photo by Glenn Fawcett.

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

The National Weather Service forecast office out at Sterling, Va., has issued a revised rainfall map covering all five days of showers and downpours from May 8 through 12. It's pretty darned impressive, especially if you live in Calvert County or parts of Anne Arundel, Prince George's County and Northern Virginia, where there seem to be patches with more than 8 inches. Feast your eyes: 

Posted by Frank Roylance at 10:01 AM | Permalink | Comments (1)
                    

It's a long way 'til Friday, but if the National Weather Service forecast holds up, we can look forward to some terrific weather for the long Memorial Day weekend - sunny skies and seasonable highs in the 70s. But first we have to sit through a couple of days of showers as a Canadian storm system sends a series of weather disturbances across the region.

Here's the deal. It's going to be a bit cool, but sunny today, as high pressure builds behind the cold front that passed by yesterday. That front is what brought us all the showers, and the dramatic clearing late in the day. Here's the link to near-real-time data from The Sun's weather station at Calvert & Centre streets.

The sunny skies and gusty winds today will yield to increasing clouds and a chance for showers late tonight. The low over southeastern Canada is turning counter-clockwise like a water wheel, and it will deliver the first packet of showers tomorrow, with rain likely in the morning before it rotates out to sea.

After a short break and a chilly night in the 40s, the next package arrives on Wednesday, with a renewed chance for showers into Wednesday evening. (No risk of an overnight record low; the BWI records are still in the 30s at this time of year.)

But then the Canadian low that's driving all this drifts away, and we come under the influence of more Canadian high pressure, forecasters out at Sterling assure us. That will mean cool, clear, dry weather from Thursday right through the long weekend. They're forecasting highs in the mid-70s - at BWI - about right for this time of year. 

Friday's a comp day for me. They had me working Sunday writing obits and covering a rained-out Studio 6001 art show in Mount Washington. (That's Sun Photog Ken Lam's photo below. We both got pretty wet out there, but the show's been rescheduled for this Sunday noon to 5 p.m.)

So now I'm looking at a four-day holiday weekend ahead with perfect weather. Hoo-wah! Anybody have any suggestions for how we should enjoy the weather this weekend? Or will the old hammock be just about right?

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

                                                                       Hurricane Dean's wreckage in Mexico - AP Photo 

We don't remember it as a particularly bad hurricane season because there was little impact in the U.S. But three storm names on last year's list for the Atlantic basin have been retired for all time because of the deaths and destruction the storms wreaked across the Caribbean, Mexico and Central America.

Members of the World Meteorological Organization's Regional Association IV Hurricane Committee voted at their annual meeting in Orlando, Fla. to permanently retire the names Dean. Felix and Noel. Normally, name lists are recycled every seven years. So these three would have reappeared on the 2013 list for the Atlantic. Instead, they will be replaced by Dorian, Fernand and Nestor.

Read more about it here.

Hurricane Dean blew into the season's first Category 5 storm and crashed ashore on the Yucatan Peninsula of Mexico on Aug. 21 last year. At least 32 people in the storm's path perished.

In September, Hurricane Felix crossed the Caribbean and it, too, became a Cat. 5 storm. It went ashore in Nicaragua as a Cat. 5 on Sept. 4, the first time two storms have made landfall at that strength in a single season since record-keeping began in 1851. Another 130 people died.

In October, Hurricane Noel formed in the Caribbean and caused great damage in the Dominican republic, Haiti, Jamaica and the Bahamas before it even reached hurricane strength. At least 160 people died.

Posted by Frank Roylance at 3:30 PM | Permalink | Comments (1)
                    

The heaviest rain is moving off to the northeast, but here the drip goes on. We have another half-inch of rain in our rain gauge this morning here at Calvert and Centre streets. That's about what they've receive down at BWI, too. But the airport is well ahead of downtown Baltimore in total rain for the month to date. And they could be headed for a record-wet May.

Chris Strong, the NWS warning coordination meteorologist out at the Sterling forecast office, reports this morning that BWI received 6.17 inches of rain between May 1 and midnight last night. Since then the airport has recorded another .56 inch. That's 6.73 inches in all. And it's only the 16th of May. (The long-term average for May in Baltimore is 3.89 inches.)

Here are some other measurements across the region. Some spots have seen more than an inch.

The record precipitation for a May in Baltimore was 8.71 inches, set back in May 1989. So if we can squeeze out another 2 inches in the next 15 days we'll have a new record.

"It's possible .... 8.71 inches certainly wouldn't be out of the question," Strong said.

Why not? We're already well ahead of the pace when compared with May 1989. In that month, the airport had recorded 5.52 inches by May 16. We've seen 6.73 inches - the most ever here for the first 16 days in May, Strong said.

The creeks are rising again. Here's the streamflow map.

And it's been a month of records. Consider:

May 9: Record rainfall for the date - 1.85 inches. That beat the 1.41 inches that fell on the date in 1919.

May 11: Record rainfall for the date - 1.49 inches. That was more than the previous record of 1.28 inches set on May 11, 1924.

May 12: A record low maximum temperature. The thermometer at BWI reached just 50 degrees Monday afternoon.  The previous record was 51 degrees, set way back, on May 12, 1882. The previous record at BWI, where official observations began in 1950, was 57 degrees, set on May 12, 1960.

May 12: Record rainfall for the date - 2.20 inches, besting the 2.06 inches that fell in 1921.

Forecasters are warning of scattered or isolated thunderstorms this afternoon as a new low moves across the region from Kentucky. "Locally damaging winds are possible," he said. Here's the forecast.

Things should start clearing up tonight. Temperatures could fall to the 40s in many locations as clouds depart and what heat we have is radiated into space.

There's a mostly sunny day in store for Saturday. But get your outdoor activities done on Saturday, because Saturday night and Sunday will get drippy again, with a 30 percent chance of showers. Monday will be better, but there are (still) more showers in the forecast for the first half of next week as a new low moves in.

You prayed for rain last October. This is it.

Oh, and by the way ... the new Drought Monitor map is in and yes, the drought is officially over, even down on the Lower Eastern Shore, where it had held on until this past weekend's rains washed it all away.

Now, the map shows only "abnormally dry" conditions on the southern Delmarva and extreme Southern Maryland on the Western Shore. The national map shows that "severe" to "extreme" drought conditions continue to our south and west, in the southern Appalachians.

Posted by Frank Roylance at 10:41 AM | Permalink | Comments (0)
                    

Tidal flooding along the Chesapeake is easing this morning. High water was flooding low-lying sections of Alexandria as southerly winds and heavy runoff from weekend storms piled water into the Cheapeake and its tidal rivers. A flood warning was issued for Alexandria and the District of Columbia.

This tide chart from Annapolis shows how far the tide readings had risen above predictions. But the red line is now falling closer to astronomical predictions. Coastal flooding advisories remain in place for today along the Western Shore of the bay, but should expire this afternoon.

Posted by Frank Roylance at 7:17 AM | Permalink | Comments (0)
                    

Satellite imagery can help us visualize large-scale events in ways that TV pictures - even those shot from helicopters - cannot.

Here is a satellite view of the smoke from the Florida wildfires, which is easily seen from space. The smoke can have a serious impact on people living downwind who may have asthma or other breathing difficulties. Here's more on the image.

And here is an image developed from radar data gathered from NASA's Shuttle Radar Topography Mission, with an overlay of quake data from the US Geological Survey.

It shows the sharply contrasting topography of the region of China devastated by this week's 7.9 earthquake. The quake was the result of the continuing uplift of the Tibetan plateau - the high country to the west of Chengdu - as the Eurasian continental plate is rammed by the Indian subcontinent in one of the planet's most dramatic manifestations of continental drift. 

The dots represent the main quake (largest circle) and subsequent, smaller aftershocks to the northeast. Read more here.   

Posted by Frank Roylance at 1:41 PM | Permalink | Comments (0)
                    

We'll get one more day to dry out from the weekend storms, forecasters say. Then, a new cold front and associated low-pressure system will bring new rains. You can see the system in the blue and red areas of this satellite image. The precip may pose issues for areas still coping with high water. But for the most part rainfall amounts will not be anything close to what we saw last weekend.

This morning's discussion from Sterling says clouds will thicken this afternoon, and the first chances for renewed shower activity will come late in the day and evening on Thursday. They're calling it scattered and isolated at first, becoming more widespread overnight into Friday before ending after noon. They're talking about a half-inch of new rain at the most. But for some, that's more than enough.

"Flooding concerns would remain ... for the trouble areas of the past few days across north central Maryland and extreme northern Virginia," the folks at Sterling said.  "Needing only around a half-inch of rain to raise area rivers to action stages." On the other hand, they added, "with area rivers beginning to drop out of flood stages and another day to recover ... the incoming rainfall may not be enough to raise concerns, but in a few isolated areas."

Coastal flooding remains a concern, too, as heavy runoff and southerly winds keep lots of water in the bay. Coastal flood advisories are posted through Thursday morning. Watch out for unusually high tides along the bay. There's a coastal flood warning up for Dorchester County, on the Eastern Shore.

Beyond the new rain, we should expect winds to pick up on Saturday morning as the passing low gets wound a little tighter. The weekend looks partly to mostly sunny, with daytime highs near 70 degrees, as the storms move away.

Posted by Frank Roylance at 10:27 AM | Permalink | Comments (0)
                    

Whew! That was a lot of water. But just how much, exactly? The numbers, of course, depend on where you were. The National Weather Service map above shows the heaviest concentration of rain south of Annapolis, chiefly in Calvert County. Here are more rain totals from around the region.

The National Weather Service instruments at Baltimore-Washington International Airport recorded 2.2 inches yesterday, a record for the date. The previous record for rain on a May 12 in Bawlmer was 2.06 inches, set in 1921. It was the third record rain total at BWI since Friday.

Altogether, the airport recorded a five-day total of 6.15 inches. That is 2.28 inches more than the long-(30-year) term average for an entire May in Baltimore. We are also running 4.73 inches ahead of the pace for the first 12 days in May.

The heaviest rain, of course, fell to the south of Baltimore. In fact, our instruments here at Calvert & Centre streets clocked in just 1.61 inches during the Sunday/Monday storm, while the airport saw 3.69  inches. Some locations saw far more, including North Beach, in Calvert County, which topped the state at more than 7 inches.

There's more rain in store. These sunny skies and 70-degree temperatures will hang around for today and tomorrow. But by Thursday you can expect increasing chances for showers as the next storm system and cold front move in from the west, much as they did last week. The next sunshine will be Monday.

Posted by Frank Roylance at 12:19 PM | Permalink | Comments (4)