Tropics Still Active

The hurricane season lasts through the end of this month and there is still activity in the Atlantic and Gulf of Mexico to monitor.

The image above shows that tropical waves continue the move off the west African coast. These disturbances are often the first phase in the development of a tropical storm or hurricane.

The image below focuses on the north Atlantic and isobars are drawn in to show the surface pressure gradient.

Early morning satellite imagery on Tuesday shows two systems. One is Ida, on the north Gulf coast and the other is a broad low pressure area in the central Atlantic that presents only a small chance of tropical development. Notice that both of these systems are on the south edge of large areas of surface high pressure.

This morning Ida was between Mobile and Pensacola and has been downgraded to tropical depression status.

Ida is forecast to move to the east and southeast as a squally storm but the effects of the storm will affect the Mid Atlantic region. Moisture is being drawn northward ahead of a cool front. The Baltimore area will be on the north edge of this pool of moisture and rain is in the forecast through Wednesday and perhaps beyond. The chart below is a computer model forecast of likely rain areas for Wednesday morning.

The rainfall estimates for Tuesday night and Wednesday are outlined below. The chart was prepared by the National Weather Service Hydrometeorological Prediction Center.

John Collins

Seasonal Benchmark

The Baltimore area hits a seasonal benchmark today. The sun sets before 5:00pm for the first time since January 6. Not counting twilight, the area will receive only 10 hours and 18 minutes of sunlight today. The earliest sunsets will occur between December 2 through 11 when darkness sets in at 4:43 each evening.

Speaking of benchmarks, the graphic below shows what the meteorological statistical averages and extremes are for this date.

John Collins

Wet Octobers & Snow

Friday night Tom Tasselmyer pulled together some preliminary statistics on October rainfall and subsequent winter snowfall. The final October numbers are in now and here are some of the conclusions.

October 2009 ties with October 1995 as the 12th. wettest on record with 6.24 inches at the official recording station at BWI-Marshall Airport.

Records date back into the late 1800s and were recorded at various locations around the city. In that time, 13 Octobers had 6 or more inches of rain. The average seasonal snowfall following those Octobers is 25.6 inches.

The average snowfall following the 10 wettest Octobers is 19.2 inches. Six of those winters were above average snow seasons and four were below average. The average Baltimore snowfall for the most recent climatological period (1971-2000) is 18.2 inches.

The statistics highlighted above would suggest that excessively wet Octobers might be indicators of snowy winters. It will be interesting to see if statistics like these reveal anything about weather patterns.

The graphic below highlights a few of those wet and snowy statistics.

John Collins

Blizzard & Tornadoes

The wild weather associated with a poweful storm tracking through the middle of the country Thursday evening is the result of a clash of seasons. The cold of winter made an early arrival on the west side of the storm, producing blizzard conditions in the Rockies. The remnants of summer’s warm and humid air along the gulf coast helped to trigger severe thunderstorms and tornadoes in Lousiana and Arkansas.

The National Weather Service in Denver, CO reported up to 42″ of snow in the mountains west of Denver, while the Severe Storms Prediction Center reported 6 possible tornadoes in northern Lousiana and southern Arkansas.

This storm will track slowly east bringing a chance for showers to the mid Atlantic region this weekend. Maryland should remain on the warm side of the storm system through Sunday, with cooler air moving back into the area next week.

Possible Tornadoes:
HAUGHTON , LA
NUMEROUS HOMES DAMAGED FROM A TORNADO SPOTTED BY A SCHOOL SUPERINTENDENT. TREES WERE DOWNED ALONG I-20 BLOCKING ALL EASTBOUND LANES.

EAST CAMDEN, AR
A TORNADO WAS REPORTED AT EAST CAMDEN AT 342 PM. TREES WERE BLOWN DOWN…WITH HIGHWAY 278/274 REPORTED TO BE IMPASSABLE.

SHREVEPORT, LA
STEEPLE ON CHURCH IN DOWNTOWN SHREVEPORT TORN OFF AND ONTO A CAR

SHREVEPORT, LA
SIGNS TORN UP AND AUTO DEALER ON FIRE OFF I-220

BOSSIER CITY, LA
POWERLINES DOWN AT THE INTERSECTION OF WEMPLE ROAD AND OLD BROWNLEE ROAD. OVERTURNED TRAILER NEAR OLD BROWNLEE ROAD

MAGNOLIA, AR
TREES DOWNED IN SE PART OF CITY NEAR COUNTY ROAD 11

Tom Tasselmyer

Rocky Mountain blizzard pumps warmth into the east

Strong low pressure over Utah has pushed the jet stream deep into the southwestern U.S., allowing unseasonably severe cold and snow to develop over the Rocky Mountains.  Snowfall of up to 4 feet is forecast in the Colorado mountains west of Denver.

The same storm, however, is pumping unseasonably warm weather into the eastern U.S.  The western storm is expected to track northeast through the great lakes and into eastern Canada, dragging a cold front through  the mid Atlantic on Sunday.

Tom Tasselmyer

Record Cold and Snow

With  temperatures stuck in the 40s again today, it looks like we’ll rewrite the October record book for the 4th straight day.  Normal highs this time of year are in the mid to upper 60s, so a day with highs in the low to mid 40s is quite a bit cooler than normal…in fact, it’s more like late December than mid October!  This December-like air mass has produced record low maximum temperatures, or perhaps a better way to express it:  record cold high temperatures, since Wednesday.

Oct. 14th:  High 50, ties record low max set in 1874
Oct. 15th: High 48, breaks record low max of 50 set in 1876
Oct. 16th: High 43, breaks record low max of 52 set in 1940
Oct. 17th: High ??, current record low max of 53 set in 1991

It is interesting to note how rare it is to set record lows, of any kind, on 4 consecutive days. In Baltimore, with weather records going back nearly 140 years, it has only happened twice. First, during the worst arctic outbreak on record for this area in February 1899. From February 9th through the 13th of 1899, 5 consecutive days set record low maximum temperatures, with afternoon highs during that stretch ranging from 3F to 10F. Then, not quite as severe, but still noteworthy, from August 28th through the 31st of 1986, four consecutive days set record lows, with low temperatures in that chilly summer air mass ranging from 45F to 49F.

So, if the temperature stays below 53F today, it will be just the third time since official weather records began in Baltimore that record lows were set on 4 consecutive days.

And, just to our north and west the record cold is producing some early season snow. In the mountains of western Maryland the first light snow of the season arrived this week, but up in Pennsylvania, it has been the heaviest snow for so early in the season at many locations. The heavy, wet snow falling on trees that still have leaves, brought down branches and caused power outages for the mountain areas of north central Pennsylvania. As of Friday the snowfall jackpot in Pennsylvania appeared to be near Nittany Mountain Summit in Centre County, with 9″ on the ground and more snow on the way!

The cold and wet weather pattern should begin to loosen its grip on the mid Atlantic late Sunday, with drier, warmer weather expected to return next week.

Tom Tasselmyer

Send To Phone

Tropics Still Active…Somewhat

So far the 2009 Hurricane Season has fallen far short of outlooks for activity in the Atlantic and Caribbean. Only six named storms have developed so far with two depressions. Back in May the outlook was for 14 named storms.

The season is not over and forecasters are monitoring developments in the Atlantic. Two weather systems are being watched as indicated in the graphic below.

#1 is northeast of the Azores and was showing rapid development Sunday evening. It is near colder water and may be shortlived if it strengthens.

#2 is a large scale tropical wave that has shown signs of organized circulation. There is a small chance that this system could develop into a depression or tropical storm.

The Hurricane Season lasts through November.

John Collins

Tsunami

An interesting map came to the weather office via Storm Center Communications.

The map below shows the various paths the “tsunami waves” followed as they moved away from the epicenter of the earthquake. Of interest is how much of the remnant “wave energy” is channeled toward the U.S. and Mexican coastline. Also note how the wave remnant that moved toward Hawaii abruptly ends, for the most part, as it runs up against the island chain.

The text and locator map following the the image are also provided by Storm Center Communications.

John Collins

This image shows the propagation of the tsunami across the Pacific Ocean.  The epicenter of the quake was near the Samoan Islands and on this map is where the tsunami is the largest (red and orange).  As the tsunami travels across the ocean it slowly dissipates until reaching the ends of the Pacific where it may be only a swell of a few centimeters.  Due to the large scale of this image, it does not represent the wave height at the Samoan Islands which has been recorded as significantly higher than 100 cm.

Additional Information:

• As of today, October 1, 139 people are confirmed dead, 22 in American Samoa, 110 in Samoa, 7 in Tonga.  It is believed that number will increase as rescuers make start to reach the outlaying villages.

• The tsunami was caused by a magnitude 8.0 earthquake that occurred on September 29 at 6:48 local time (17:48 UTC).  The epicenter (star) was 120 miles south of the city of Apia, Samoa near the Kermadec-Tonga Subduction Zone (purple line) where the Pacific Plate dives under the Australian Plate in the Pacific Ring of Fire.

Weekend Rain Totals

The weekend rainfall produced some much needed precipitation for the area.

• 1.48″  …  TV-Hill
• 1.38″  …  Inner Harbor
• 1.31″  …  BWI-Marshall (3.41″ for September)

The rain totals for other Maryland locations are supplied by the National Weather Service.

John Collins

PUBLIC INFORMATION STATEMENT
SPOTTER REPORTS
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1250 PM EDT SUN SEP 27 2009

THE FOLLOWING ARE UNOFFICIAL OBSERVATIONS TAKEN DURING THE PAST 24
HOURS FOR THE STORM THAT HAS BEEN AFFECTING OUR REGION.
APPRECIATION IS EXTENDED TO HIGHWAY DEPARTMENTS...COOPERATIVE
OBSERVERS...SKYWARN SPOTTERS AND MEDIA FOR THESE REPORTS.  THIS
SUMMARY IS ALSO AVAILABLE ON OUR HOME PAGE AT WEATHER.GOV/BALTIMORE

********************STORM TOTAL RAINFALL********************

LOCATION          STORM TOTAL    TIME/DATE    COMMENTS
                     RAINFALL       OF
                     (INCHES)   MEASUREMENT

DISTRICT OF COLUMBIA

...DISTRICT OF COLUMBIA...
   NATIONAL ARBORETUM    1.56  1000 AM  9/27
   DALECARLIA RESERVOIR  1.32  1100 AM  9/27
   WASHINGTON            1.07   800 AM  9/27   2 S TAKOMA PARK

MARYLAND

...ALLEGANY COUNTY...
   FROSTBURG             1.19  1000 AM  9/27

...ANNE ARUNDEL COUNTY...
   ANNAPOLIS             2.00  1200 PM  9/27
   ODENTON               1.67  1000 AM  9/27
   PASADENA              1.58  1000 AM  9/27
   SOUTH GATE            1.58  1000 AM  9/27
   CROFTON               1.55  1000 AM  9/27
   SOUTH GATE            1.54  1000 AM  9/27   3 SW

...BALTIMORE COUNTY...
   KINGSVILLE            1.52  1000 AM  9/27
   CATONSVILLE           1.44  1000 AM  9/27
   TOWSON ESTATES        1.43  1000 AM  9/27   2.5 ENE
   JACKSONVILLE          1.42  1000 AM  9/27
   TOWSON PARK           1.42  1000 AM  9/27
   LONG GREEN            1.34  1000 AM  9/27

...CALVERT COUNTY...
   NORTH BEACH           2.16  1000 AM  9/27
   DUNKIRK               1.91  1000 AM  9/27
   PRINCE FREDERICK      1.46  1000 AM  9/27

...CARROLL COUNTY...
   SYKESVILLE            1.43  1000 AM  9/27
   WOODBINE              1.40  1000 AM  9/27
   ELDERSBURG            1.24  1000 AM  9/27
   MOUNT AIRY            1.09  1000 AM  9/27

...CHARLES COUNTY...
   WALDORF               1.77  1000 AM  9/27   3.6 SSE
   WALDORF               1.70  1058 AM  9/27   3.2 SW
   LA PLATA              1.64  1000 AM  9/27
   WALDORF               1.47  1000 AM  9/27

...CITY OF BALTIMORE...
   HAMILTON              1.47  1000 AM  9/27

...FREDERICK COUNTY...
   THURMONT              0.96   800 AM  9/27

...HARFORD COUNTY...
   BEL AIR               1.14  1000 AM  9/27
   HAVRE DE GRACE        1.14  1000 AM  9/27
   FALLSTON              1.13  1000 AM  9/27
   JARRETTSVILLE         1.10  1000 AM  9/27

...HOWARD COUNTY...
   MARRIOTTSVILLE        1.50  1000 AM  9/27
   ELLICOTT CITY         1.45  1000 AM  9/27
   COLUMBIA              1.42  1000 AM  9/27
   WHITE OAK ESTATES     1.37  1000 AM  9/27

...MONTGOMERY COUNTY...
   MONTGOMERY VILLAGE    1.67  1000 AM  9/27
   WHEATON               1.40  1000 AM  9/27
   TAKOMA PARK           1.39  1000 AM  9/27
   GLENMONT              1.35  1000 AM  9/27
   VALLEYWOOD PARK       1.26  1000 AM  9/27

...PRINCE GEORGE`S COUNTY...
   FRIENDLY              1.95  1000 AM  9/27
   CAMP SPRINGS          1.87  1000 AM  9/27
   FOREST HEIGHTS        1.78  1000 AM  9/27
   OXON HILL             1.75  1000 AM  9/27
   BOWIE                 1.73  1000 AM  9/27

...ST. MARY`S COUNTY...
   LEONARDTOWN           1.95  1000 AM  9/27
   PARK HALL ESTATES     1.81  1000 AM  9/27
   RIDGE                 1.57  1000 AM  9/27

...WASHINGTON COUNTY...
   WILLIAMSPORT POWER    0.94  1000 AM  9/27

Gloria

John Collins