Tropical Topics: 2009 Eastern Pacific Hurricane Season Opens

May 15 is the opening day of the Eastern Pacific hurricane season. Since many storms in this region do not threaten land, the extent of activity was not fully realized until the satellite observation era. On average, there are 15 tropical storms and 9 hurricanes per year in the North Pacific east of 140 west longitude. The list of storm names for this season is:

NAME           PRONUNCIATION    NAME            PRONUNCIATION
-------------------------------------------------------------
ANDRES         AHN DRASE-       MARTY
BLANCA         BLAHN- KAH       NORA
CARLOS                          OLAF            OH- LAHF
DOLORES                         PATRICIA        
ENRIQUE        ANH REE- KAY     RICK
FELICIA        FA LEE- SHA      SANDRA
GUILLERMO      GEE YER- MO      TERRY
HILDA                           VIVIAN
IGNACIO        EEG NAH- CIO     WALDO
JIMENA         HE MAY- NA       XINA            ZEE- NAH
KEVIN                           YORK
LINDA                           ZELDA           ZEL- DAH 

The National Hurricane Center will be making several changes this season in tropical storm reporting:

• The Tropical Weather Outlook, issued 4 times a day, will include categorical probabilities of storm development: Low (less than 30%), Medium (30-50%), High (over 50%).
• The Saffir-Simpson scale traditionally used to classify hurricane strength will be modified on an experimental basis to exclude storm surge and flooding indications. The reason for doing this is that the Saffir-Simpson scale is primarily a measure of maximum wind speed, but storm surge is affected by several other factors, such as storm size and forward speed, shape of coastline, and water depth. For example, Hurricane Ike last year made landfall as a Category 2 storm, but the storm surge was comparable to what is currently defined as a Category 4-5 storm. Emergency management officials reported that many residents refused to evacuate since the storm was "only" a Category 2 or 3 as it approached land. Likewise, Katrina (2005) had Category 3 winds at landfall, but the storm surge was equivalent to Category 5. On the other hand, Hurricane Charley (2004) had Category 4 winds but only Category 2 storm surge.

The Atlantic season will begin in 2 weeks, on June 1.

CapitalClimate provides a number of links to national, local, and international tropical storm information in the list to the left titled "Tropical Topics". Discussions of significant storms will be provided in blog posts as appropriate during the hurricane season.

Image: Eastern Pacific Tropical Outlook from National Hurricane Center.

April 2009 5th Warmest on Record Globally Year to Date Tied for 6th Warmest

Global

The National Climatic Data Center's preliminary analysis released today shows that global temperatures for April 2009 were the 5th warmest on record. This makes April somewhat warmer relative to average than March. For the January-April period, temperatures were tied with 2003 as the 6th warmest. The warmest regions relative to average were Mexico, the northeastern U.S., southern South America, and most of Europe and Asia. Areas with cooler than average temperatures were north central to southeastern U.S. and western Asia.

United States

For the contiguous United States overall, the average temperature was "51.2°F (10.7°C), which was 0.8°F (0.5°C) below the 20th century mean and ranked as the 36th coolest April on record, based on preliminary data." Regionally, much of the country had near average temperatures, but the West North Central region was cooler than average. The Northeast was warmer; New Hampshire had its 8th warmest April in records dating back to 1895.

NOAA's Residential Energy Demand Temperature Index indicates that energy demand due to temperature was 2.3% below average.

Australia

The Australian Bureau of Meteorology reports that a sharp cold outbreak in the final week of the month set several record lows. The reading of -13.0°C (8.6°F) on April 29 at Charlotte Pass was a new record minimum temperature for all of Australia in April. An April record for the state of Victoria of -8.2°C (17.2°F) was set at Mount Hotham. For the country as a whole, however, Australia was "slightly warmer and drier than average" in April. Although temperatures were near or below average in the population centers of the southeast, they were generally above normal elsewhere.

Europe

In the UK, the Met Office reports that monthly temperatures were above average across the whole country, "ranging from about 1.3°C above in south-west England and south Wales to about 2.3°C above in East Anglia, south-east England and northern Scotland.

The warmth extended to northern Europe, where Deutscher Wetterdienst announced that the monthly temperature for Germany of 11.8°C in April was 4.5° above average. This made April 2009 the warmest April in records dating back to 1891. Average sunshine was 62.5% above normal, making this the second sunniest April after 1951.

Images (click to enlarge):
From NCDC/NOAA:

• Global land and sea temperature departures from average for April 2009
  
• Historical April global land and ocean temperature departures from average
  
• Historical contiguous U.S. April temperature departures from average
  
• U.S. categorical temperature ranks for April 2009

From Australian Bureau of Meteorology:

• Average daily maximum temperature departure from average for April 2009

From UK Met Office:

• UK monthly temperature departure from average for April 2009

From Deutscher Wetterdienst:

• Average monthly temperature in Germany, April 2009

Mid Atlantic Drought Update: Short-Term Surplus Continues to Erase Long-Term Deficit

5 pm Update: Daily/monthly totals through 5:00:

Washington National 0.48"/3.18"
Washington Dulles   0.18"/2.96"
Baltimore (BWI)     0.56"/3.88" 

BWI is now above average for the year by slighly over half an inch.

PM Update: (Added the longer-term percentage of average precipitation analyses which were not available this morning.)
Although they don't include the locally heavy downpours since 8 am this morning, the water-year (since Oct. 1) and 90-day maps below show widespread areas from northern Virginia through Maryland (including the District of Columbia) at 90% or less of average precipitation amounts. So, although gardeners and farmers may be complaining about an excess of rainfall in the shorter term, longer term hydrological issues may be a concern if the current wet period fails to continue.



Images (click to enlarge): Water-year (since Oct.1) and 90-day percentage of average precipitation ending 8 am this morning from National Weather Service

Original post:

Note from Baghdad-on-the Potomac: This post has been delayed by an hour thanks to repeated drops of the Comcast Internet connection. The Verizon land line backup went out of service on May 1 and is expected to require 18 days to repair.

Images (click to enlarge): Weekly and 24-hour precipitation ending 8 am this morning from National Weather Service

The latest U.S. Drought Monitor report, released this morning by the USDA and NOAA, shows that continuing rainfall in the past week has erased the minimal drought levels in most of the Mid Atlantic area. Maryland and Delaware have been completely removed from the Abnormally Dry category, and Virginia has been reduced from 85% to 53%. To the north, dry conditions are continuing in Pennsylvania, but its Abnormally Dry area has been reduced from 91% to 71%.

In the Washington DC area, above-average spring precipitation has nearly wiped out the previous year-to-date deficit. At Washington National, just under an inch of rain yesterday brought the May total to almost 400% of the average to date. This amount was further supplemented by additional heavy showers overnight. Amounts were even higher in the Baltimore metro area, where many locations received up to 2" in the 24 hours ending at 8 am this morning.

Through midnight, year-to-date precipitation totals and departures from average were:

Washington National 11.92"/-8%
Washington Dulles   12.29"/-8%
Baltimore (BWI)     14.18"/0% 

Mid Atlantic Drought Update: Deficits Continue Eroding

Images (click to enlarge): 24-hour total precipitation and 90-day percentage of average precipitation ending at 8 am EDT Monday, from National Weather Service Precipitation Analysis.

PM Update: As of 5 pm, additional rain during the day has further pushed down the deficits to as low as 10% for the year. Year-to-date totals and departures from average are now:

Washington National 10.69"/-18%
Washington Dulles   11.32"/-13%
Baltimore (BWI)     12.54"/-10% 

Original Post:
Following extremely dry conditions for the first quarter of 2009, a wet April has led into a soggy May in the Mid Atlantic area. Through 8 am this morning, 24-hour precipitation over 1" was widespread in the northern Virginia/DC/Maryland region. Daily totals in the immediate vicinity of Washington, DC were:

Washington National 1.11"
Washington Dulles   1.32"
Baltimore (BWI)     1.11" 

These amounts, and additional rainfall during the day, will continue to erode the lingering deficits. As of midnight, the year-to-date departures from average were:

Washington National -2.45"/-19%
Washington Dulles   -2.54"/-20%
Baltimore (BWI)     -2.04"/-17% 

Zipper Majors in Skepticism

The class is botany, but it might as well be climatology.

Image (click to enlarge): Doonesbury Flashback, April 30, 2009

Greatest Fall at Great Falls All-Time Snowfall Record Set

The snowstorm in Montana this week has set an all-time record for a single storm at Great Falls; records there extend back to 1886. The National Weather Service reports that the heaviest snow fell over the northern portions of the Rocky Mountain front on the Blackfeet Indian reservation. Storm totals as high as 60" were reported. Some locations have already reported their snowiest season on record.

Image (click to enlarge): April 27-30 snowfall totals from National Weather Service, Great Falls, Montana

RECORD EVENT REPORT 
NATIONAL WEATHER SERVICE GREAT FALLS MT  
415 AM MDT THU APR 30 2009 
MTZ008>015-044>055-302400- 

...RECORD HIGH TWO AND THREE DAY STORM TOTAL SNOWFALL AT GREAT FALLS  
MONTANA... 

STORM TOTAL SNOWFALL AT THE GREAT FALLS AIRPORT FOR THE THREE DAY  
PERIOD OF APRIL 27...28...29 MEASURED 25.4 INCHES. THIS IS AN ALL  
TIME THREE DAY SNOWFALL RECORD WHICH SURPASSES THE PREVIOUS RECORD  
OF 18.1 INCHES SET NOVEMBER 26...27...28 IN 2005. 

SNOWFALL AT THE GREAT FALLS AIRPORT FOR THE TWO DAY PERIOD OF APRIL  
28...29 MEASURED 24.2 INCHES. THIS IS ALSO AN ALL TIME SNOWFALL  
RECORD WHICH SURPASSES THE PREVIOUS RECORD OF 17.3 INCHES SET APRIL  
19...20 IN 1973. 

THE ALL TIME ONE DAY SNOWFALL RECORD AT THE GREAT FALLS AIRPORT IS  
16.5 INCHES SET ON APRIL 20 IN 1973. THE 16.1 INCHES RECORDED  
YESTERDAY...APRIL 29TH...IS THE SECOND HIGHEST ONE DAY SNOWFALL  
TOTAL RECORDED SINCE CLIMATIC RECORDS BEGAN AT GREAT FALLS IN 1886. 

 
..RECORD HIGH PRECIPITATION FOR APR 29 IN NORTH CENTRAL MONTANA 

LOCATION             NEW RECORD       OLD RECORD       YEAR SET 

GREAT FALLS AIRPORT    0.87              0.43            1913 

 
..RECORD HIGH SNOWFALL FOR APR 29 IN NORTH CENTRAL MONTANA 

LOCATION             NEW RECORD       OLD RECORD       YEAR SET 

GREAT FALLS AIRPORT    16.1              5.4             1913  

PUBLIC INFORMATION STATEMENT 
NATIONAL WEATHER SERVICE GREAT FALLS MT  
1110 AM MDT THU APR 30 2009 
 
..RECAP OF THE SNOWSTORM THIS WEEK 

THE INFORMATION LISTED IS AS OF 10 AM MDT APRIL 30. 

THE STORM THAT BROUGHT RECORD AMOUNTS OF SNOW TO CENTRAL AND NORTH  
CENTRAL MONTANA THIS WEEK IS NOW WINDING DOWN. THE HEAVY  
SNOWFALL...CAUSED ROADS AND AIRPORTS TO CLOSE...PRODUCED POWER  
OUTAGES...AND FORCED THE CLOSURE OF MANY AREA SCHOOLS. 

IT BEGAN WITH SNOW FALLING ALONG THE ROCKY MOUNTAIN FRONT MONDAY  
MORNING /APRIL 27/ AND CONTINUED WITH PERIODS OF HEAVY SNOW ON  
TUESDAY AND WEDNESDAY BEFORE DECREASING TO LIGHT SNOW ON THURSDAY  
MORNING /APRIL 30/. STRONG WINDS PUSHED THE SNOW INTO DRIFTS AS HIGH  
AS 10 TO 12 FEET OVER PORTIONS OF THE ROCKY MOUNTAIN FRONT. 

THE HEAVIEST SNOW FELL OVER NORTHERN PORTIONS OF THE ROCKY MOUNTAIN  
FRONT ON THE BLACKFEET INDIAN RESERVATION. OVER TWO FEET OF SNOW  
FELL AS FAR EAST AS THE GREAT FALLS AREA...WITH MUCH LIGHTER AMOUNTS  
IN THE HAVRE AND LEWISTOWN AREAS. MOST OF BLAINE COUNTY AND EASTERN  
PORTIONS OF FERGUS COUNTY PRIMARILY MEASURED RAINFALL. EVEN THE  
RAINFALL WAS HEAVY WITH GRASS RANGE REPORTING OVER 2.3 INCHES OF  
PRECIPITATION WITH ONLY 3 INCHES OF SNOW. CHINOOK REPORTED JUST  
UNDER ONE INCH OF RAIN /0.90/. 

FOLLOWING IS A TABLE WITH SOME OF THE SNOWFALL AMOUNTS REPORTED FROM  
MONDAY THROUGH THURSDAY MORNING... 

             SNOW...WATER EQUIV   ...BOTH VALUES IN INCHES... 
ST MARY........ 60  
BABB VICINITY.. 48  
BADGER PASS.... 43     2.80 
DUPUYER CREEK.. 34     3.00 
MT LOCKHART.... 34     2.00 
WALDRON........ 34     2.00 
ROGERS PASS.... 26.7   1.30 
PIKE CREEK..... 26     1.50 
GREAT FALLS.... 25.4   1.65 
BROWNING....... 24 
CUT BANK 10W... 24 
PENDROY........ 20 
PICKFOOT CREEK. 20 
CHOTEAU........ 18.7 
BENCHLAND...... 18 
CARTER 25N..... 18 
CHOTEAU 8NE.... 16 
HOBSON......... 16 
CRYSTAL LAKE... 16     1.10 
HELENA 3S...... 14 
DAISY PEAK..... 14     1.50 
GOLD BUTTE..... 13     0.58 
MONTANA CITY... 13 
MILLEGAN....... 13     0.56 
ROCKY BOY...... 13     1.50 
CHOTEAU........ 12.5 
MONARCH........ 12 
CASCADE 5SSE... 12 
STANFORD....... 12     1.13 
VALIER......... 11.7   1.89 
CONRAD......... 11 
MANY GLACIER... 11     0.50 
NEIHART........ 10.1   0.47 
CASCADE 20SSE..  8 
BOZEMAN MSU....  6 
WHITE SULPHUR..  6     0.53 
FORT BENTON....  4.5   1.75 
RUDYARD 19S....  4     0.75 
GRASS RANGE....  3     2.32 
BOULDER........  2      
FT ASSINNIBOINE  1.3   1.05 
VALENTINE......  0.2   1.70 
CHINOOK........  0     0.90 

THE RECENT SNOWS HAVE ADDED TO THE LARGE AMOUNTS OF SNOW RECORDED  
OVER THE PAST WINTER ACROSS MUCH OF THE AREA. SOME LOCATIONS HAVE  
RECORDED THEIR SNOWIEST SEASON OF RECORD...WITH THE SNOW SEASON NOT  
YET FINISHED. FOLLOWING IS A TABLE WITH SNOWFALL TOTALS FOR THE  
SEASON AND OTHER RECORD INFORMATION... 

                 2008-09 SNOWFALL 
CHINOOK...........  103.1 INCHES     SNOWEST OF RECORD...OLD RECORD 63 
                                    INCHES IN 1995-96. 
CHOTEAU...........   65.6            3RD SNOWIEST...RECORD IS 90 INCHES 
                                    IN 1966-67. 
FT ASSINNIBOINE...   78.2            THE SNOWIEST OF RECORD AND THE SNOWIEST 
                                    SINCE 1989-90...50.1 INCHES. 
GOLD BUTTE........   91.4            RECORD IS 127 INCHES IN 2006-07. 
GRASS RANGE.......   88.6            4TH SNOWIEST...RECORD IS 118 INCHES 
                                    IN 1966-67. 
GREAT FALLS.......  108.6            2ND SNOWIEST OF RECORD...THE RECORD 
                                    IS 120.2 INCHES IN 1988-89. THIS 
                                    IS THE 4TH SEASON IN WHICH THE  
                                    SEASONAL SNOWFALL HAS EXCEEDED 100 
                                    INCHES. THE AVERAGE IS 62  
                                    INCHES. 
MILLEGAN..........  187.3            SNOWIEST...OLD RECORD IS 186  
                                    INCHES IN 2003-04. 
STANFORD..........   77.5 

FOR THE MONTH OF APRIL...SOME SNOW RECORDS HAVE ALSO FALLEN. AT  
BOZEMAN MSU...49.4 INCHES OF SNOW HAVE FALLEN. THIS EXCEEDS THE  
RECORD OF 37 INCHES IN APRIL 1955. THIS IS ALSO THE MOST MEASURED IN  
ANY MONTH AT BOZEMAN MSU. THE OLD RECORD WAS 44.3 INCHES IN NOVEMBER  
1941. THIS IS ALSO THE WETTEST APRIL OF RECORD...4.40 INCHES OF  
PRECIPITATION HAS FALLEN. THE OLD RECORD WAS 3.59 INCHES IN 1912 AND  
2003. 

AT CUT BANK...THE 11 INCHES OF SNOW ON THE GROUND ON APRIL 30 IS THE  
GREATEST RECORDED ON ANY DAY IN APRIL. THE OLD RECORD WAS 10 INCHES  
ON APRIL 30 1967.  

Mid Atlantic Drought Update: Dryness Spreads Northward

1:30 pm Update: Added Washington, DC data and chart

Original post:
The dryness associated with record heat in the Mid Atlantic and Northeast has increased the extent of the minimal drought coverage in those areas. This week's U.S. Drought Monitor, released this morning, shows Maryland, Delaware, and New Jersey continuing with 100% in the Abnormally Dry (D0) category. Meanwhile, Virginia has increased from 80% to 85%. The extent of the dry area has expanded to the north, with the Northeast overall rising from 33% to 48%. The biggest increases are in Pennsylvania, rising from 56% to 91%, and New York (8% to 32%). Connecticut has also increased, from 67% to 79%. The Abnormally Dry area has crept northward into western Massachusetts; that state's coverage has increased from 0 to 25%.

In the Washington DC area, the mostly dry week has added to the accumulated deficit. The year-to-date precipitation totals and departures from average are:

Washington National: 9.22"/-24%
Washington Dulles:   9.51"/-24%
Baltimore (BWI):    10.86"/-18% 

Images: U.S. Drought Monitor for week ending April 28 (yellow shading indicates Abnormally Dry/D0 conditions); Washington DC 90-day precipitation from Climate Prediction Center/NCEP/NWS