Archive for April, 2009

April 28, 2009

It’s on your car and in your eyes and nose. Pollen is everywhere.

The early season heat wave has coincided with the flowering of numerous types of trees in the region to produce very high pollen count readings.

  • Trees ….. 2223   very high
  • Grass ….. 20   moderate
  • Weeds …  3    low
  • Total …..  2256    very high

Rain will be coming into the picture and that should help to settle some of this pollen dust down, but the trees will continue to produce high volumes of pollen in the near future.


The satellite image above clearly shows the “Bermuda High Pressure” feature over the Atlantic Ocean and eastern seaboard that has been responsible for the hot, dry weather. The high pressure area is shifting east and south and that will allow a frontal boundary to the west to move in with a rain chance and cooler temperatures.

Speaking of temperatures … no records yet. Monday’s high in Baltimore of 91 fell one degree short of tying the record for the date. The record for Tuesday is 90 and afternoon temperatures could get close. Stay tuned.

John Collins


No Records Yet
April 27, 2009

A summerlike heat wave of sorts is in progress but no temperature records have fallen yet. The list below shows the record highs for the given days followed by the actual/forecast high temperature.

  • Friday       93(1960) .. 72
  • Saturday    94(1960) .. 90
  • Sunday      92(1990) .. 91
  • Monday     92(1994) .. 91(forecast)
  • Tuesday     90(1957) .. 86(forecast)

The typical high temperature for this time of year is in the upper 60s to near 70 degrees. The forecast map for Monday evening shows the unseasonably warm air still in place.


The Bermuda high pressure ridge responsible for pumping the warm air into the region will begin to break down on Tuesday and temperatures will start to back off.

John Collins

Summer Temperatures
April 26, 2009

A summer weather pattern has set up over the eastern U.S. The result, warm temperatures.


Saturday’s high of 90 was short of the record 94. The Sunday record high temperature is 92 and is a bit more vulnerable to being tied or broken.

The “heat wave” will continue through Tuesday. Unsettle weather moves in Wednesday and will continue into the weekend with more clouds, rain chances and cooler, but still mild temperatures.

John Collins

More Rain?
April 22, 2009

Tuesday turned out to be a fairly nice day … until late afternoon when scattered showers and thunderstorms broke out. The set up is similar today.


The morning visible satellite image above and the surface map depiction below shows that a broad low pressure area continues to spin over the Great Lakes and Northeastern U.S.


Once again today, scattered showers and thunderstorms are likely to develop in the area. How much?

fill_94qwbgThe map above shows that up to a quarter inch of rain is possible over most of Maryland, perhaps a little more to the west.

The Thursday morning forecast map indicates that the area will start to come under the influence of high pressure as the low pressure system moves out.


Thursday should be the start of a string of days of dry weather and warmer temperatures that should last into next week.

Where does the area stand so far on the rain issue? Well, April has done an abrupt turnaround from a dry winter. The graphic below is a snapshot of the BWI-Marshall record book as of Midnight, Tuesday, April 21.

statsj1The 5.65 inches of rain so far this April is not a record breaker … yet. In 1889 the April record of 8.70 inches of precipitation was measured in Baltimore and that would be tough to match. The 30 year average precipitation for April is 3.00 inches so the area is ahead of the game and has gone much of the way toward making up the for dry winter months.

John Collins

Preliminary Monday Rain Numbers
April 20, 2009

As of 5:00pm Monday, Here is how the numbers stacked up at BWI_Marshall Airport.


For a broader look at rain totals, the image below is a “snapshot” of the National Weather Service Radar at Sterling, Virginia. It is set to display the estimated storm precipitation total.


Much of the area west of I-95 received around an inch of rain. Portions of Carroll, Harford and Cecil counties, as well as the Eastern Shore, measured less than an estimated two thirds of an inch.

The rainfall has become more scattered but the storm is not over. The storm’s low pressure center will continue to affect the region into mid week.


The late afternoon visible satellite image shows the heavy cloud deck over most of Maryland with a more scattered cloud cover over southern Virginia. The sun, along with a more southerly wind fetch, helped move temperatures into the 70s in Virginia while readings were stuck in the 50s around Baltimore because of a more easterly wind and the clouds. The warmer temperatures to the south increased instability in the atmosphere and strong thunderstorms developed. They are evident in the satellite picture as the “puffier” streaks of clouds aligned southwest to northeast. There will be a severe weather potential in the warmer region until the sun sets and temperatures cool later this evening.

John Collins

Another Soaker On The Way
April 20, 2009

A slowly advancing storm system gave the area some great weekend weather but the start of the work week will be very wet.

The storm center will be spinning between the Ohio Valley and the Great Lakes for the next two or three days.


The cold front associated with the low pressure center will be moving into the mountains on Monday and a warm front will be moving north. The combined flow of moisture from the Atlantic Ocean and the Gulf of Mexico will generate some significant rainfall, perhaps in the neighborhood of 1.5 inches.

While April has received an abundance of rain, the area is still short of the average for 2009 and this rain “event” will help to close the gap.

By the end of the week, drier conditions and warmer temperatures should return.

John Collins

Clear Sailing … For A While
April 16, 2009

The sun is out and the area should stay dry for a couple of days.

The updated rain numbers at BWI-Marshall

  • Monday … 0.11 inches
  • Tuesday … 0.21 inches
  • Wednesday … 1.14 inches
  • April …  4.11 (2.61 inches above the seasonal average)
  • 2009 … 9.17 inches (2.75 inches below the seasonal average)

The gap is slowly closing for the longer term dry spell.

It looks sunny and dry going into the weekend but the next storm is brewing out west.


The midday satellite image shows the generally clear conditions over the east and the unsettled weather out west. With the sun, temperatures will warm up. By the end of the weekend the stormier weather out west will be edging closer and rain chances are expected to increase.

John Collins

Another Soaker
April 15, 2009

Update … 10:45pm April 15, 2009

As of 5:00pm Wednesday, .99 inches of rain was measured at BWI-Marshall since midnight, bringing the April rain total to 3.96 inches, 2.46 inches above the seasonal average for the month. The 2009 precipitation remains below the average to date by 2.9 inches. Wednesday’s final precipitation total will not be finalized until after midnight.

Previous post …..

A two day soaker is now in the process of moving away from the area.


While it has been dreary and chilly, the rain has been welcome across much of the region because of an unusually dry winter. At the end of the day Tuesday (April 14), rainfall at BWI-Marshall was in surplus for April by 1.56 inches. For 2009 it is a different story with a deficit of 3.8 inches.

The image below is a National Weather Service radar analysis of the precipitation that has fallen in the Baltimore-Washington area since Monday.


The most significant rains are estimated to have fallen from the Baltimore and Washington metro areas, eastward. The green shaded areas have received up to around an inch of rain (Baltimore City & County, Harford County and eastern Anne Arundel County). On the other hand, western portions of Carroll and Howard counties have received only about a third of an inch of rain.

A break in the rain should arrive Thursday with some sunshine and warmer temperatures.

John Collins

Student Curiosity
April 15, 2009

Tuesday morning (4/14/09) I had the opportunity to talk weather with a great group of 5th & 6th grade students from the Jemicy School of Owings Mills. They had a lot of interesting questions and are fascinated by the technology we use today.


John Collins

April Showers
April 11, 2009

The latest round of April showers will be pulling out of the area Saturday afternoon. Rainfall totals have been in the .5 to 1.5 inch range around Baltimore based on National Weather Service radar estimates.radj

The green shades north and east of Baltimore are the areas that received the most significant rainfall.

A couple of days of chilly, dry air will follow the departing storm.


NASA/NOAA Satellite Image

The satellite image above shows the clearing behind the storm plus a developing storm out west that bring more rain to the area Monday night or Tuesday.

Also on the image, note the gray and white shading north of the Great Lakes and around Hudson Bay. The sky is cloud free and the image is showing the extensive snow cover that remains in Canada. Much of Hudson Bay appears ice covered but some of the bright white shading is either thin cloud cover or fog.

A final note. Today is a benchmark of sorts in the Baltimore weather record books. The record snowfall for the day is 2 inches, set back in 1894. This is the last day on record in April that an inch or more of snow fell in Baltimore. There are now only five dates between Sunday and the end of the month that received less than a half inch of snow and nine dates that recorded only trace amounts of snow. It is an encouraging sign that, at least from the climatological records point of view, spring is taking hold.

John  Collins