Archive for November, 2009

El Nino and Mid Atlantic Winters
November 26, 2009

Because El Nino conditions are expected in the tropical Pacific Ocean this winter, the good folks down at the Baltimore/Washington National Weather Service Forecast Office took a look at the impact El Nino has on winter weather patterns here in the Baltimore-Washington area.  The results of the research compiled by meteorologist Jared Klein are posted below.  For snow-lovers, at least, it is most likely good news as long as the El Nino episode does not become too strong.

Tom Tasselmyer

El Nino and Mid Atlantic Winter

Jared Klein
General Forecaster
National Weather Service
Baltimore/Washington

November 2009

The official National Oceanic and Atmospheric Administration (NOAA) Winter Outlook from the Climate Prediction Center (CPC) was released back in mid-October. The outlook favors below average temperatures and equal chances for above or below average precipitation in the greater Baltimore and Washington DC area for the upcoming 2009-2010 winter season (see figures below).  El Niño, which is a climate phenomenon characterized by unusually warm ocean temperatures in the tropical Pacific Ocean, is expected to play a key role in influencing this upcoming winter’s weather across the United States.

Looking back at past winters since 1950, approximately 17 were influenced by an El Niño episode. The figures below are composites of average December, January, and February (DJF) temperatures and precipitation, as well as seasonal snowfall at Washington, D.C. broken down by the strength of the El Niño episode. Both DJF temperatures and precipitation averaged near normal while seasonal snowfall averaged a few inches above normal. The strength of the warming in the equatorial Pacific Ocean (i.e. El Niño episode) shows a possible correlation to seasonal temperature, precipitation, and snowfall locally at Baltimore and Washington D.C.  Weak El Niño winters averaged below normal temperatures and precipitation, while strong El Niño episodes have resulted in above normal temperatures and precipitation. On average, the stronger the El Niño episode, the warmer and wetter the winters have been. These findings can largely  be linked to a stronger than normal sub-tropical jet that typically occurs during moderate to strong El Niño winters, which would favor more active storm systems from the south that draw warm, moist air northward as opposed to the drier Alberta clippers from the northwest. Seasonal snowfall averaged above normal for weak and moderate El Niño winters while below normal for strong El Niño episodes. During strong El Niño episodes, the bulk of the cold air remains north of the mid-Atlantic region, often resulting in precipitation falling as rain instead of changing to snow.

Not all El Niño winters are alike as many other shorter and longer term climate patterns influence the local weather. For example, although it might seem that all strong El Niño winters in Washington D.C. and Baltimore have been associated with above normal temperatures and precipitation and below normal snowfall; these atmospheric quantities have been variable each winter. Of the 17 El Niño winters, eight had above normal snow while nine were below normal.  The above average El Niño winters have been associated with some of our snowiest winters, especially during moderate El Niño episodes. With the ongoing El Niño episode expected to continue, even strengthen to moderate levels this winter, El Niño will likely play an important role with the winter climate here in the greater Baltimore and Washington D.C. area.

More Wet Weather
November 24, 2009

The forecast calls for unsettled weather most of this week. That translates to rain and drizzle, and perhaps a few snowflakes before it’s all over.

If it has seemed grey and wet this month you are right. 10 days in November have had overcast or mostly overcast skies while only 6 days have had clear or mostly clear conditions. As of Monday, 3.53 inches of rain has been measured at BWI-Marshall Airport, 1.18 inches above the 30 year seasonal average. Despite the generally dreary conditions, November temperatures have been on the mild side, averaging 4 degrees above average.

This month is one of many in 2009 that have had a relatively high number of days of measurable precipitation.

  • January       7
  • February      5
  • March          11
  • April             12
  • May              18
  • June             12
  • July               8
  • August         12
  • September   11
  • October        13
  • November    9 (as of Nov 24)

The National Weather Service graph below outlines 2009 temperatures and precipitation to date.

John Collins

NOAA Aerial & Underwater Pictures of Nor’easter Impacts on S.E. VA
November 16, 2009

A NOAA ship and aircraft responded to last week’s nor’easter which affected the mid Atlantic region and pounded the Hampton Roads area of southeast VA.  NOAA  provided critical aerial and underwater (hydrographic) imagery to the port community, local officials, and residents impacted by the storm.

From the NOAA press release:

NOAA Plane Captures Photos of Flooding & Grounded Barge

NOAA Cessna Citation (tail number N52RF), based out of Tampa, a versatile twin-engine jet aircraft, acquired remote sensing imagery this weekend along the Hampton Roads shoreline.  The aircraft is equipped with two equal-sized camera ports which can support a wide variety of remote sensing configurations including large format aerial photography.  Now available on Google Earth, some images snapped by the plane include…the grounded barge on Virginia Beach.

 

NOAA Ship Finds Chesapeake Bay Bridge Tunnel Safe

NOAA Ship Thomas Jefferson, homeported in Norfolk, conducted emergency hydrographic surveys in Cape Henry and the Elizabeth River to locate submerged debris, shoals, and other hazards to maritime navigation caused by the storm.  Attached is an image captured by a multibeam echo sounder that shows the Chesapeake Bay Bridge Tunnel riprap is holding and the tunnel is safe.  NOAA survey vessels like the Thomas Jefferson conduct surveys in support of updating NOAA nautical charts, as well as respond when plane crashes, vessel groundings, or other accidents require underwater coastal searches and investigations.

Tom Tasselmyer

 

 

Nor’easter Lashes Coast
November 14, 2009

tt_StormStats

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1035 AM EST FRI NOV 13 2009

...PUBLIC INFORMATION STATEMENT...

...POWERFUL STORM SETS RECORD WAVE HEIGHT AT NOAA BUOY 44009...

THE POWERFUL EAST COAST STORM CONTINUES TO GENERATE LARGE WAVES
ALONG THE COAST AND ACROSS THE LOWER DELAWARE BAY. THE NOAA BUOY
44009...DELAWARE BAY BUOY LOCATED 26 MILES SOUTHEAST OF CAPE
MAY...RECORDED A HEIGHT OF 26.7 FT. THIS IS THE HIGHEST WAVE
HEIGHT RECORDED SINCE THE BUOY WAS DEPLOYED IN 1984. THE SECOND
HIGHEST HEIGHT WAS 25.4 FT IN A 2003 WINTER STORM.

THE MOMENTUM AND ENERGY FROM THESE LARGE WAVES MOVING TOWARD THE
MAINLAND ARE LARGELY RESPONSIBLE FOR THE WATERS UNABLE TO DRAIN FROM
THE BACK BAYS.

WAVES BREAKING ON THE BEACHES OF LONG BEACH ISLAND REACHED AT
LEAST 9 FT...AND AT LEAST 10.4 FEET ON BETHANY BEACH DELAWARE.

THE DELAWARE COASTAL MANAGEMENT BUOY...INSIDE THE LOWER DELAWARE
BAY...RECORDED 7.9 FEET.



PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE WAKEFIELD VA
130 PM EST FRI NOV 13 2009

...INTENSE COASTAL STORM BROUGHT HEAVY RAIN...STRONG WINDS...AND
CONSIDERABLE COASTAL FLOODING TO THE THE MID ATLANTIC REGION...

THE FOLLOWING ARE UNOFFICIAL RAINFALL TOTALS AND PEAK WIND GUSTS
FROM BUOYS...ASOS AND AWOS SITES...SINCE 600 AM WEDNESDAY THROUGH
FRIDAY MORNING.

***************************************************************

LOCATION                              PEAK WIND GUST (MPH)

KNTU (OCEANA VA)                              75  (614 PM EST)
KORF  (NORFOLK VA)                            74  (611 PM EST)
CHYV2 (CAPE HENRY VA)                         72  (543 PM EST)
CBBV2 (CHESAPEAKE BAY BRIDGE TUNNEL VA)       71  (800 PM EST)
YKRV2 (YORK RIVER LIGHT VA)                   66  (506 PM EST)
44009 (BUOY 15NM E OF FENWICK IS DE)          62  (400 PM EST)
RPLV2 (RAPPAHANNOCK LIGHT VA)                 61  (230 PM EST)
KWAL (WALLOPS ISLAND VA)                      59  (758 PM EST)
YKTV1 (YORK CG TRAINING FACILITY)             58  (212 PM EST)
WAHV2 (WACHAPREAGUE VA)                       57  (600 PM EST)
WEST CRADOCK (SE PORTSMOUTH)                  57  (1023 PM EST)
KOXB (OCEAN CITY MD)                          56  (1215 PM EST)
KECG  (ELIZABETH CITY NC)                     54  (204 PM EST)
DUKN7 (DUCK PIER NC)                          53  (1012 AM EST)
ASTM2 (ASSATEAGUE ISLAND)                     52  (1140 PM EST)
OCIM2 (OCEAN CITY INLET MD                    44  (848 AM EST)


***************************************************************

LOCATION                                        RAINFALL (IN)

IN MARYLAND...

...WORCESTER COUNTY...

   OCEAN CITY (KOXB)                            4.32 (THROUGH 1 PM)

   BISHOPVILLE 3.1 E (COCORAHS)                 4.78 (THROUGH 6 AM)


...WICOMICO COUNTY...

   SALISBURY (KSBY)                             3.95 (THROUGH 1 PM)

   SALISBURY 2.5 WSW (COCORAHS)                 3.72 (THROUGH 6 AM)

NWS/AKQ

November Nor’easter
November 12, 2009

tt_noreaster_12nov09

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE WAKEFIELD VA
1000 PM EST THU NOV 12 2009

...INTENSE COASTAL STORM CONTINUES TO BRING AREAS OF RAIN AND STRONG
WINDS TO THE MID ATLANTIC REGION...

AREAS OF MODERATE TO HEAVY RAIN CONTINUE ACROSS PORTIONS EASTERN AND
CENTRAL VIRGINIA. EXCESSIVE WIND GUSTS OCCURRED OVER PORTIONS OF
SOUTHEAST VIRGINIA...REACHING IN EXCESS OF 70 MPH AT TIMES.

LOW PRESSURE SYSTEM NEAR CAPE HATTERAS AT 9 PM WAS MOVING VERY SLOWLY

RAINFALL AMOUNTS HAVE VARIED OVER THE REGION DURING THE PAST 60 HOURS
...WITH THE HEAVIEST RAINFALL OCCURRING OVER SOUTHEAST VIRGINIA.
RAINFALL AMOUNTS IN THIS REGION HAVE RANGED FROM 6 TO 9 INCHES SINCE
TUESDAY NIGHT...WITH LOCALLY HIGHER AMOUNTS.

***************************************************************

LOCATION                              PEAK WIND GUST (MPH)

CBBV2 (CHESAPEAKE BAY BRIDGE TUNNEL VA)       71  (800 PM EST)
CHYV2 (CAPE HENRY VA)                         72  (543 PM EST)
YKRV2 (YORK RIVER LIGHT VA)                   66  (506 PM EST)
KORF  (NORFOLK VA)                            74  (611 PM EST)
RPLV2 (RAPPAHANNOCK LIGHT VA)                 60  (230 PM EST)
KWAL (WALLOPS ISLAND VA)                      59  (758 PM EST)
WAHV2 (WACHAPREAGUE VA)                       57  (600 PM EST)
KNTU (OCEANA VA)                              75  (614 PM EST)
KOXB (OCEAN CITY MD)                          56  (1215 PM EST)
KECG  (ELIZABETH CITY NC)                     54  (204 PM EST)
OCIM2 (OCEAN CITY INLET MD                    44  (848 AM EST)
44009 (15NM E OF FENWICK IS DE)               62  (400 PM EST)
DUKN7 (DUCK PIER NC)                          53  (1012 AM EST)

***************************************************************

LOCATION                                        RAINFALL (IN)

IN MARYLAND...

...WORCESTER COUNTY...

   OCEAN CITY (KOXB)                            3.60 (THROUGH 9 PM)

...WICOMICO COUNTY...

   SALISBURY (KSBY)                             3.10 (THROUGH 8 PM)


IN VIRGINIA...

...NEWPORT NEWS...

   NEWPORT NEWS/WILLIAMSBURG INTL ARPT (KPHF)   8.99 (THROUGH 8 PM)

...NORFOLK...

   NORFOLK INTL AIRPORT (KORF)                  6.06 (THROUGH 8 PM)

...HAMPTON...

   LANGLEY AIR FORCE BASE (KLFI)                9.07 (THROUGH 8 PM)

...VIRGINIA BEACH...

   OCEANA NAVAL AIR STATION (KNTU)              7.82 (THROUGH 8 PM)

...CHESAPEAKE...

   CHESAPEAKE MUNICIPAL AIRPORT (KCPK)          4.67 (THROUGH 8 PM)

...SUFFOLK...

   SUFFOLK MUNICIPAL AIRPORT (KSFQ)             5.70 (THROUGH 8 PM)

...SUSSEX COUNTY...

   WAKEFIELD MUNICIPAL AIRPORT (KAKQ)           5.65 (THROUGH 8 PM)

Tropics Still Active
November 10, 2009

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

latestfullThe 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.

20091110.0900.composite.SeaLevelPress_model_overlays_eatl_atlantic.xEarly 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.

vistuesfctuej

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.

gfs_pcp_024m

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

fill_94qwbg

John Collins

Seasonal Benchmark
November 7, 2009

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.

JC_Avg

John Collins

Wet Octobers & Snow
November 2, 2009

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.

JC_RainyOctober

John Collins