Archive for May, 2007

Looking For Rain
May 31, 2007

As the final hours of May 2007 countdown the rainfall deficit for the month is approaching three inches. After ample rains in March and April, the month of May has produced just .94″ of rain through the 30th at our official National Weather Service observing station at BWI-Marshall. Normal rain for the month is 3.89″. There is hope for some moisture, however, as we head into June. Hot, humid conditions may lead to a few pop-up thunderstorms through the weekend and then, perhaps, a more significant rain will spread north from the gulf of Mexico. Satellite pictures show a developing area of low pressure near the Yucatan peninsula. This system has a chance to take on tropical-like characteristics as it moves north across the gulf of Mexico this weekend. Some computer models bring this storm onshore near Pensacola, FL Sunday morning. From there the system has a chance to spread significant rain north into the mid Atlantic states Sunday night and Monday. The track of the storm is uncertain at this time and if it stays farther east, as some computer models are indicating, our chance for significant rain will diminish. Something to watch over the next few days.

Tom Tasselmyer


Recent Memorial Day Rains
May 28, 2007

The Memorial Day weekend has evolved into the unofficial start of summer and most folks would prefer “perfect” weather for the extended weekend. The average high temperature for the end of May is in the upper 70s and the low is in the mid 50s. The late spring season typically experiences frequent rains and in recent years Memorial Day itself has had a rather wet reputation. Only one out of the past five Memorial Days has been rain free. That was last year when the temperature hit 92 and the skies were partly cloudy. Below is the recent Memorial Day track record for weather.

2002: High temperature 80 … cloudy/thunderstorms … rainfall .18″
2003: High temperature 69 … cloudy/rain/fog … rainfall 1.51″
2004: High temperature 70 … cloudy/rain … rainfall .48″
2005: High temperature 78 … partly cloudy/showers … rainfall .02″
2006: High temperature 92 … partly cloudy … no rain

This Memorial Day, an approaching cool front will keep rain chances alive during the day. Any thunderstorm activity will likely be scattered and the day does not look like it will be a washout. Just keep alert for any storm activity that could crop up.

Speaking of rain … the Baltimore area is running a little short of what is considered “normal”. As of late Sunday afternoon, the official rain total for May was only .94″ which is 2.45″ below the 30 year average. Evening rains around town generally produced less than a tenth of an inch and any rain on Monday is not expected to be substantial so it looks like we will need to do some catching up to keep things green in the area. A more substantial storm system is expected next weekend and it may help.

John Collins

Be Wary Of Long Range Hurricane Forecasts
May 24, 2007

With this week’s release of the official 2007 Atlantic hurricane season forecast from the National Oceanic and Atmospheric Administration (NOAA), came the usual bevy of news reports about what we should “expect” this summer and fall in the tropics. To summarize, the good folks at NOAA are looking for 13 to 17 named storms, with 7 to 10 of those becoming hurricanes and 3 to 5 of those hurricanes strengthening to category 3 or higher (winds above 110 mph). This seems like a good forecast, and I think those tropical weather experts at NOAA do a fantastic job of keeping us up-to-date on the latest trends in tropical weather, but let’s remember this is a long range forecast, and long range forecasts frequently bust. We only have to look back to last year’s hurricane season forecast to find a big-time forecast bust…a season that was supposed to be “very active” ended up less than average. In fact, over the past 5 hurricane seasons NOAA has correctly forecast the number of hurricanes just once (2003) and the number of named storms only twice. The three predictions NOAA makes each May are: named storms, hurricanes and major hurricanes. Their forecast has missed for all three categories in each of the past two seasons. Here’s a summary of the May hurricane forecasts issued for the past five years:

It is extremely difficult to forecast anything in the world of meteorology beyond a few days, so trying to predict what will happen across the vast area of the tropical Atlantic and Caribbean for the next six months is a monumental task, to say the least. And, in the end, it really is not the number of named storms or hurricanes that matters, it’s where those storms track that is most important. It only takes one storm, making landfall in a highly populated area, to create a dangerous situation.

Tom Tasselmyer

More Like Spring
May 21, 2007

The past week has felt a bit more like the spring we all know and love. Daytime temperatures have been warming up and readings are much closer to normal for the season. It looks like that trend will continue in the coming week. In fact we should wind up with above average temperatures by the end of the week.

Precipitation is a different story. Rainfall has been a bit skimpy recently and not evenly distributed. The most significant recent rain was last Wednesday, ranging from .21″ to .52″. This was not enought to stop a rising shortfall over the area. As of Sunday, May 20, BWI-Marshall is running 1.54″ below average on rain for the month and 1.27″ below average for the year. The pattern for the week ahead is not a wet one and the next best rain chance is next weekend.

Just what is “normal” for this time of year? The average low temperature for today is 53 and rises to 55 by Saturday. The average high for today is 75 and jumps to 77 by Saturday. On average, rainfall in the coming week would total .91″.

The weather for the coming week is expected to be warmer and generally dry but an approaching cold front could bring some rain by late Saturday, although it may not amount to much. Even though some rain would be ideal at this stage, the week ahead should be pleasant. Enjoy.

John Collins

21st Century Preakness Rain
May 18, 2007

There is a possiblity of some showers for the 132nd running of the Preakness this Saturday, but what else would you expect? The 21st century has produced just one “3rd Saturday in May” that did not have at least a trace of rain in Baltimore. Here’s the rundown of the observed weather for the first seven Preakness Saturdays since 2000:

2006: Hi 73 Lo 50 Rain: Trace
2005: Hi 74 Lo 41 Rain: 0
2004: Hi 87 Lo 65 Rain: .17″
2003: Hi 52 Lo 48 Rain: .06″
2002: Hi 62 Lo 47 Rain: .73″
2001: Hi 79 Lo 61 Rain: .10″
2000: Hi 56 Lo 54 Rain: .03″

For 5 of the 7 races the track at Pimlico has been rated “Fast” with the other 2 races (2003 and 2000), run on tracks rated “Good”.

So the average 21st century Preakness Saturday looks something like:

Mostly cloudy
Hi 69 Lo 52
Rain: .16″
Track: Fast

This Saturday’s weather will largely depend on the track of a storm off the coast and low pressure in the upper atmosphere. If the storm tracks close enough to the coast, or the upper low lingers over the mid Atlantic states, scattered showers will develop Saturday. Even without showers, gusty winds and cool temperatures appear likley. The early forecast includes northwest winds of 15-20 mph with temperatures in the mid 60s to low 70s.

Tom Tasselmyer

Helpful Rain
May 14, 2007

This past Saturday the area received its’ first significant rain since April. It did not produce even results though. BWI-Marshall officially received .30″ but the Inner Harbor received just over an inch as did many areas of eastern Baltimore, Harford and Cecil counties. Elkton checked in with 1.17″. On TV Hill we measured .76″ but in contrast, many parts of Howard County received less than .30″ with Ellicott City measuring only .03″.

As of Sunday, Baltimore is running .92″ below normal for 2007, 1.05″ above normal since March 1 and 1.19″ below normal for this month. The upshot is that many areas still need a good rain. More rain is in the forecast by mid-week.

Temperatures will be all over the ballpark this week. Monday morning is expected to start out in the 40s in the metro area but perhaps some upper 30s could crop up to the north and west. Parts of Pennsylvania and western Maryland may even experience some patchy frost. Highs should just break into the 70s on Monday but shoot into the 80s again on Tuesday ahead of a cool front. After that front passes it looks like the week ends with highs only in the 60s to near 70.

Preakness is Saturday and for the moment the forecast looks favorable but there is a potential fly in the ointment. A storm developing southeast of Florida will be heading north during the week and it should carry a load of tropical moisture with it. Computer models are keeping it relatively far off shore until the weekend when it could drift into New England. A shift in timing or track is something to watch for. If it does wind up near New England on Saturday, disturbances rotating around its’ outer edges may change the flavor of the weather in Baltimore. Stay tuned. This uncertainty is typical in longer range forecasts and we’ll have to see how the various computer models play out over the next few days.

John Collins

May 9, 2007

It has been more than a month since the last flakes of snow were spotted around here (0.2″ on April 7th), but for snow lovers the”season” comes to an official close today. It was on this day, May the 9th back in 1923 that the latest recorded snowflake was observed in Baltimore. Never, in the 130+ years of official weather records for Baltimore, has snow fallen after May the 9th. So, the final numbers for the 2006-2007 season will show 11.0″ inches of snow measured at BWI-Marshall, which is 7.2″ below the 30 year average. The snowfall deficit was all a result of the warm January, during which less than 1″ of snow fell in a month that typically produces about 7″ of snow. After January, the winter settled into a fairly typical mid-Atlantic pattern. Here’s the monthly snowfall breakdown:

Nov. 2006: 0
Dec. 2006: Trace
Jan. 2007: 0.9″
Feb. 2007: 8.5″
Mar. 2007: 1.4″
Apr. 2007: 0.2″

With Baltimore’s earliest observed snow coming on October 9th, back in 1979, next “season” is exactly five months away. Hang in there snow fans!

Tom Tasselmyer

Getting Dry .. Spring Chill .. Developing Storm
May 7, 2007

It has been a while since we’ve had a good rain in the area. A region wide soaker produced almost 4 inches of rain over a five day period in mid April. It is now 21 days since that happened and in that time we have received only .62″ of rain. Statistically the area is 1.58″ above normal for rainfall since March 1 but .66″ below normal for the month of May. The reserve that the excessive April rainfall produced is being drawn down rapidly at this point. It appears that the next best rain chance is at the end of the week and may produce only scattered results. Plants in areas that have soils with poor moisture retention could begin to experience some stress so keep an eye on the lawn and garden.

A bubble of dry, chilly Canadian air has once again moved into the area with the prospect for a brief shot of unseasonably chilly temperatures. Frost and freeze conditions are possible to the west. Cold sensitive plants that have already been put outside may need some protection for the next couple of nights.

A weather disturbance is developing off the southeast coast of the U.S. This disturbance will be stalled over the Gulf Stream for several days and will likely strengthen a bit before it finally washes out. Because it will be over the relatively warm waters of the Gulf Stream there is a small chance that the disturbance could begin to take on some tropical characteristics. No matter how things turn out it is a reminder that the hurricane season officially begins in less than a month and it expected to be a busy one.

John Collins

Best Weather Of The Year?
May 5, 2007

A big snowstorm on the coast can be a beautiful thing in mid winter. A clear, frosty morning followed by a sunny, chilly afternoon is what I look forward to in October. I can even enjoy a few hazy, hot days in mid summer. But in early May it’s hard to beat what we were treated to Friday afternoon, at least in my book. The official numbers at BWI-Marshall airport look like this:

High: 71
Low: 42
Afternoon relative humidity: 21%
Average wind: 5.2 mph
Sky: Mostly sunny

I hereby nominate May 4th for best weather day of the year so far! Hope you had a chance to enjoy it.

Tom Tasselmyer