Friday, October 29, 2010

Data Review Reveals Midwest Cyclone Missed All-Time Record by 0.01"

A review of the observations from Tuesday's intense cyclone and historical records by the National Weather Service (NWS) and National Climatic Data Center (NCDC) has determined that the current storm's low pressure missed the all-time Continental U.S. record by the smallest possible margin, 0.01". The 28.20" altimeter setting reported at Bigfork, Minnesota (station ID KFOZ) has been corrected to 28.21" (955.2 mb), based on a more accurate adjustment of the raw observed station pressure to sea level. The more precise calculation takes into account the actual observed temperature, as opposed to an assumed U.S. standard atmosphere.

Also, NCDC has found 2 verified observations at 28.20" (955.0 mb):
     13 January 1913 at Canton, New York
7 March 1932 at Block Island, Rhode Island
(Note, however, that Block Island is located a little more than 10 miles off the coast of Rhode Island, so it doesn't strictly meet the definition of mainland Continental U.S.)

On the other hand, a lower reported reading of 951.6 millibars at Bridgehampton, NY on March 3, 1914 cannot be confirmed by the NCDC (although that, too, is technically not a mainland reading, since it's on Long Island).

The current storm is clearly the record-holder for lowest pressure in an extratropical storm away from the Atlantic or Pacific coasts. The previous record was held by the Great Lakes storm of January 26, 1978. That storm had a reading of 956.0 mb at Mount Clemens, Michigan, which exceeded the frequently-reported 957.7 at Cleveland. According to the NWS, "The January 26, 1978 storm later went on to produce lower sea level pressure readings in Ontario, Canada, including a 955.5 millibar reading at Sarnia."

The report goes on to cite record lower pressures elsewhere in the U.S.:
  • For a tropical cyclone: "The lowest sea level pressure recorded at any United States certified observing station was 892 millibars (26.34"), recorded at Matecumbe Key, Florida on September 2, 1935 in the 'Labor Day Hurricane'."
  • Beyond the Continental U.S.: "The lowest sea level pressure recorded in a non-tropical (extratropical) storm at any United States certified observing station was 927 millibars (27.35"), recorded at Dutch Harbor, Alaska on October 25, 1977."
Image (click to enlarge): Minimum sea level pressure reported October 25-26, 2010; annotations indicate location of observations; from NWS

Thursday, October 28, 2010

Mild Minneapolis Finally Freezes


October 29 Update: The morning low was 28° at Minneapolis and 31° at Chicago.

Original post:
At 10 pm EDT tonight, the official Minneapolis temperature reached 32° for the first time this season. This ends the string of freeze-free days at 22 past the average date of October 6 and ties for the 10th latest date of first frost. October so far is averaging 6.4° above the climatological mean.

Chicago has still not yet reached 32°, although a low of 31° is forecast by morning.

Image (click to enlarge): Temperature, dewpoint, relative humidity, and precipitation at Minneapolis for the week ending October 28, 2010, from National Weather Service

Wednesday, October 27, 2010

Battle of the Bombs: Northwest Contests Record Storm Claim

October 29 Update: The status of the pressure record has been updated as a result of further review.

Original post:
University of Washington meteorologist Cliff Mass (h/t to American Meteorological Society's Front Page blog) is disputing claims that yesterday's storm was the most intense non-tropical system over the continental U.S. He points out that some storms in the past over the Pacific Northwest have had stronger winds, because they had stronger pressure gradients (rate of change of pressure with distance):
There has been a lot of media attention regarding the storm in the Midwest with claims it was the strongest (lowest pressure) non-tropical storm in U.S history. DON'T BELIEVE IT FOR A MOMENT. This is classic eastern U.S. media myopia....we have had the deepest and most violent storms!
He doesn't provide evidence of lower barometric pressures than yesterday's storm over land, however. Dr. Jeff Masters points out at Weather Underground:
The modern Pacific Coast record is 28.40" (962mb) at Quillayute, Washington on Dec. 1, 1987. An older reading, taken on a ship offshore from the mouth of the Umpqua River in Oregon during the famous "Storm King" event on January 9, 1880, is tied with yesterday's 28.20" (955 mb.)

The lowest non-hurricane barometric pressure reading in the lower 48 states is 28.10" (952 mb) measured at Bridgehampton, New York (Long Island) during an amazing nor'easter on March 1, 1914 (see Kocin and Uccellini, "Northeast Snowstorms; Vol. 2., p. 324, American Meteorological Society, 2004.) The lowest non-hurricane barometric pressure reading from anywhere in the United States was a 27.35" (927 mb) reading at Dutch Harbor, Alaska on Oct. 25, 1977. The lowest hurricane pressure reading was the 26.34" (892 mb) recorded in 1935 during the Great Labor Day Hurricane.

All-Time Low Pressure Record Update

October 29 Update: The status of the pressure record has been updated as a result of further review.

10 PM Update: The National Weather Service reports that La Crosse, Wisconsin set an all-time low pressure record:
AT 553 AM ON OCTOBER 26TH...THE BAROMETRIC PRESSURE FELL TO   
971.4 MILLIBARS /28.685 INCHES OF MERCURY/. THIS JUST BARELY BEAT
THE PREVIOUS RECORD OF 971.6 MILLIBARS /28.691 INCHES OF MERCURY/
ON NOVEMBER 10 1998. THE TABLE BELOW CONTAINS THE FIVE LOWEST
BAROMETRIC PRESSURES AT LA CROSSE WI SINCE 1933.

LOWEST BAROMETRIC PRESSURE READINGS
AT LA CROSSE WI
1933 TO PRESENT

SEA LEVEL
SEA LEVEL PRESSURE
PRESSURE IN INCHES
RANK IN MILLIBARS OF MERCURY DATE TIME
---- ------------ ---------- ---- ----
1 971.4 28.685 10/26/2010 553 AM
2 971.6 28.691 11/10/1998 150 PM
3 971.9 28.700 04/03/1982 900 AM
4 973.6 28.750 11/11/1940 700 PM +
5 973.8 28.756 01/11/1975 500 AM

+ ARMISTICE DAY STORM
It was the second-lowest pressure ever recorded at Wausau, Wisconsin, and the fourth-lowest at Green Bay:
...2ND LOWEST PRESSURE EVER RECORDED IN WAUSAU TODAY...
...LOWEST OCTOBER PRESSURE ON RECORD AT WAUSAU TODAY...

AN INTENSE AUTUMN STORM DROPPED THE PRESSURE TO 28.65 INCHES
AT 805 AM THIS MORNING AT WAUSAU. THIS IS THE 2ND LOWEST PRESSURE
EVER RECORDED IN WAUSAU AND IS THE LOWEST PRESSURE ON RECORD FOR
THE MONTH OF OCTOBER. PRESSURE RECORDS HAVE BEEN KEPT IN WAUSAU
SINCE 1950.

HERE ARE SOME OF THE LOWEST OCTOBER PRESSURE READINGS AT WAUSAU.

RANK PRESSURE DATE / YEAR
-----------------------------------------------------------
1 28.65 26 2010
2 28.93 30 1996
3 29.05 19 2007
4 29.10 18 2007

HERE IS A LIST OF THE LOWEST PRESSURE READINGS EVER RECORDED
AT WAUSAU.

RANK PRESSURE DATE YEAR
------------------------------------------------------------
1 28.58 APR 03 1982
2 28.65 OCT 26 2010
3 28.67 JAN 11 1975
4 28.69 NOV 10 1969
5 28.77 NOV 11 1998
6 28.88 MAR 02 2007

NOTE: PRESSURE RECORDS BEGAN IN 1950.

...4TH LOWEST PRESSURE EVER RECORDED IN GREEN BAY TODAY...
...2ND LOWEST OCTOBER PRESSURE ON RECORD AT GREEN BAY TODAY...

AN INTENSE AUTUMN STORM DROPPED THE PRESSURE TO 28.78 INCHES
AT 824 AM THIS MORNING IN GREEN BAY. THIS IS THE 4TH LOWEST
PRESSURE EVER RECORDED IN THE CITY AND 2ND LOWEST OCTOBER
PRESSURE ON RECORD.

HERE ARE SOME OF THE LOWEST OCTOBER PRESSURE READINGS AT
GREEN BAY.

RANK PRESSURE DATE / YEAR
-----------------------------------------------------------
1 28.76 19 1937
2 28.78 26 2010
3 28.95 30 1996
4 29.05 19 2007
5 29.11 27 1995

HERE IS A LIST OF THE LOWEST PRESSURE READINGS AT GREEN BAY.

RANK PRESSURE DATE YEAR
-----------------------------------------------------------
1 28.45 APR 3 1982
2 28.69 DEC 14 1920
3 28.76 OCT 19 1937
4 28.78 OCT 26 2010
5T 28.80 FEB 11 1932

5T 28.80 NOV 10 1940
5T 28.80 JAN 11 1975
8 28.88 NOV 10 1998
9T 28.89 NOV 19 1957
9T 28.89 NOV 11 1998

NOTE: PRESSURE DATA BEFORE 1949 WAS TAKEN FROM AVAILABLE SOURCES.
NOT ALL MAXIMUM AND MINIMUM PRESSURE EVENTS MAY HAVE BEEN DOCUMENTED
BEFORE 1949.
12 PM Update: The Minnesota State Climatology Office reports:
On October 26, a large storm system dominated the continental United States. This is one of the strongest non-tropical storms on record for lowest minimum pressure in the United States. The lowest pressure found so far with the October 26 storm was 28.20 inches at 5:13pm at Bigfork in Itasca County. This shatters the old Minnesota lowest pressure record of 28.43 that was set in the November 10, 1998 storm at both Austin and Albert Lea. The strongest Great Lakes area storm in terms of pressure was the "Great Ohio Blizzard" of Janaury 26, 1978. The pressure minimum of this storm was 28.05, which was likely measured in southern Ontario. Thus, it appears that the minumum pressure of 28.20 inches measured at Bigfork is the new record low pressure for a non-tropical strom in the Continental US (excluding tornadoes).

This storm rapidly intensified over the course of 24 hours. Aided by a strong jet stream, a strong low pressure system became better organized over central South Dakota on October 25. The low moved to the northeast and by noon on October 26, the center was over Hibbing. High Wind Warnings were posted from southeast Montana to Ohio. A Blizzard Warning covered a good chunk of North Dakota. Winds were gusting up to 59 mph near Hanley Falls at 1:15pm on the 26h.

To illustrate how strong of a storm this is, 28.20 inches is equivalent to a Category 3 Hurricane. The lowest pressure for the storm that sank the Edmund Fitzgerald on November 10, 1975 was 28.95 inches. Even with the Armistice Day storm, the lowest pressure recorded was 28.55 inches. Of course, pressure is only one measurement of a storm.

During the evening hours of October 26, snow became mixed with the rain over northern Minnesota, by daybreak on October 27, a white blanket of snow covered parts of northern Minnesota. The heaviest snow total found so far was near Twig in St. Loius County with 9 inches. The Duluth National Weather Service Office measured 7.4 inches. Not only snow, but heavy rains fell as well with this storm with 3.92 inches reported in three days at Wolf Ridge in Lake County.
Original post:
The National Weather Service issued a statement this morning on the all-time low pressure records set yesterday by the very intense storm centered in Minnesota. Note that the new Minnesota record, if confirmed, is almost 8 millibars lower than the old record. The usual spacing between isobars on a weather map is 4 mb.
THIS IS A PRELIMINARY STATEMENT ON THESE PRESSURE RECORDS. HERE IS   
WHAT WE KNOW SO FAR ABOUT THE LOW PRESSURE RECORDS SET ON OCTOBER
26TH:

AN UNUSUALLY INTENSE LOW AFFECTED THE STATE OF MINNESOTA. AT 513 PM
CDT...THE AUTOMATED WEATHER OBSERVING SYSTEM AT BIGFORK MINNESOTA
RECORDED A 954.96 MILLIBAR /28.20 INCHES/ PRESSURE. THIS BREAKS THE
ALL TIME MINNESOTA STATE RECORD FOR THE LOWEST OBSERVED PRESSURE.

THE PREVIOUS RECORD WAS 962.6 MB SET ON NOVEMBER 10 1998 AT ALBERT
LEA AND AUSTIN IN SOUTHERN MINNESOTA. THE RECORD WAS INITIALLY
BROKEN SHORTLY AFTER 10 AM AS THE LOW PASSED BY AITKIN MINNESOTA.
HOWEVER...THE LOW CONTINUED TO INTENSIFY INTO THE AFTERNOON.

DULUTH
THE LOW PRESSURE RECORD AT DULUTH WAS SET AT 1113 AM
WITH A PRESSURE OF 960.72 MILLIBARS /28.37 INCHES/. THE PREVIOUS
RECORD WAS 964.3 MILLIBARS WHICH OCCURRED ON NOVEMBER 10 1998.

INTERNATIONAL FALLS
THE LOW PRESSURE RECORD AT INTERNATIONAL
FALLS WAS SET AT 345 PM WITH A PRESSURE OF 955.98 MILLIBARS /28.23
INCHES/. THE PREVIOUS RECORD WAS 971.9 MILLIBARS ON OCTOBER 10 1949.

WISCONSIN
THE LOW PRESSURE RECORD FOR THE STATE OF WISCONSIN WAS
SET IN SUPERIOR AT 1115 AM WITH A PRESSURE OF 961.06 MILLIBARS
/28.38 INCHES/. THE PREVIOUS RECORD WAS 963.4 MILLIBARS WHICH
OCCURRED AT GREEN BAY ON APRIL 3 1982.
Image (click to enlarge): Surface weather map at 4 pm CDT, October 26, approximately 1 hour before the all-time record low barometric pressure observation

Tuesday, October 26, 2010

Update: Record Extended to Entire Mainland U.S.;
All-Time Record Low Pressure in Minnesota and Wisconsin

October 29 Update: The status of the pressure record has been updated as a result of further review.

8:30 PM CDT Update: The St. Cloud daily record precipitation has increased to 1.42".

The Illinois State Climatologist quotes the National Weather Service:
New record set today for the lowest pressure in a non-tropical storm in the mainland U.S. The massive storm system barreling across the central U.S. had a minimum central pressure of 28.24″ or 956 mb (equivalent to the minimum pressure of a Category 3 hurricane). This breaks the old record of 28.28″ (958 mb), set on Jan. 26, 1978, during the Blizzard of 1978 (aka the Cleveland Superbomb). This is also lower than the March 1993 Superstorm (aka “The Storm of the Century”), or the “Witch of November” storm that sank the Edmund Fitzgerald in 1975, or even the Columbus Day Storm of Oct. 1962.
Note that the Big Fork report apparently exceeded that reading by an additional 0.04".

5:40 PM CDT Update: Big Fork and Orr appear to have bottomed out with slight rises back to 28.22" shortly after 5:30.

St. Cloud has set a rainfall record for the second consecutive day. The 1.38" today broke the old record of 1.33" set in 1941.

5:15 PM CDT Update: Big Fork forges onward to a new low of 28.20".

4:40 PM CDT Update: Although the storm is centered in Minnesota, it's strong enough to break the all-time record in the neighboring state of Wisconsin, as well. The National Weather Service reported earlier this afternoon that the low pressure of 28.38" (961.1 mb) at Superior broke the previous record of 28.45" at Green Bay on April 3, 1982.

4:30 PM CDT Update: The Weather Channel is twitching that the Orr reading is the "Record lowest U.S. land-based pressure! . . . [B]esting the record from 'Superbomb of Jan '78'!" Presumably, this means the lowest reading from a non-tropical storm. Meanwhile, Big Fork has slightly surpassed that with a pressure of 28.21" at 4:13 pm.

4 PM CDT Update: The image (click to enlarge) shows the surface weather map at 1 pm CDT this afternoon, as barometric pressures approached new all-time record lows in Minnesota. The central pressure of the intense storm is shown as 957 mb (28.26").

3:45 PM CDT Update: Big Fork and Orr are tied at 28.22".

Bloomberg reports that the strong winds from the storm have "knocked out power to thousands in Illinois, Indiana and Michigan and forced the cancellation of hundreds of flights at Chicago airports."

3:15 PM CDT Update: The drop continues: Big Fork 28.22", Orr 28.23".

3 PM CDT Update: Orr and Big Fork are both down another notch to 28.24".

2:15 PM CDT Update: Grand Rapids has tied Orr at 28.27", but Orr has come in with a late report of 28.25" at 1:54.

2 PM CDT Update: The latest hourly readings show 5 official stations all at 28.28": Big Fork, Cook, Eveleth, Grand Rapids, Hibbing.

1:40 PM CDT Update: Orr has continued to fall, now at 28.27"; Eveleth at 28.28"; Cook, Hibbing, and Grand Rapids all at 28.29".

1:30 PM CDT Update: Orr has now tied the 28.29" reading as of 1:14.

The storm also brought record daily rainfall yesterday to Minneapolis. The 0.67" exceeded the old record of 0.62" in 1875. St. Cloud's 0.61" also broke the daily record of 0.50" set in 1956.

1 PM CDT Update: As of 1 pm local time, Eveleth was reporting a new low of 28.29" with pressure still falling. Other new lows included:
HIBBING      28.30
GRAND RAPIDS 28.32
COOK 28.33
LONGVILLE 28.33
ELY 28.35
ORR 28.35
AITKEN 28.35
MCGREGOR 28.35
Original Post:
As predicted yesterday, a strong storm has intensified rapidly over Minnesota, bringing with it an unofficial all-time record low pressure for the state. At noon CDT, Longville in north-central Minnesota was reporting a barometric reading of 28.36" (960.4 mb), and the pressure was continuing to fall. Hibbing also recorded the same reading. According to the National Weather Service, the previous record low pressure for the state was 28.43" (962.8 mb) in 1998.

Other stations reporting pressures below 28.50" include:
BEMIDJI           28.41
THIEF RIVER FALLS 28.49
FOSSTON 28.45
PARK RAPIDS 28.45
BAUDETTE 28.47
INTL FALLS 28.46
BIG FORK 28.42
GRAND RAPIDS 28.38
COOK 28.41
DULUTH 28.39
ELY 28.41
GRAND MARAIS 28.49
AITKIN 28.38
PINE RIVER 28.44
BRAINERD 28.42
STAPLES 28.48
LITTLE FALLS 28.49
MORA 28.49
MOOSE LAKE 28.38
HINCKLEY 28.45
CLOQUET 28.39
It appears that at least 10 of these locations broke the old record.

Monday, October 25, 2010

Fall Freeze-Free Excess Extended;
Minneapolis at 19 Days Beyond Average First Frost, Record Low Pressure Possible

Following a low temperature of 36° on Friday, Minneapolis has extended its string of days without frost to 19 days past the average date of the first 32° temperature. Lows on Saturday, Sunday, and this morning were 52°, 53°, and 52°, respectively. Following the passage of a strong storm, temperatures will drop by midweek, with lows of 34° predicted for Wednesday and Thursday. The expected low of 31° on Friday would make this the 9th latest first freeze, tied with 1963.

The 0.01" of rainfall on Saturday ended the 27-day dry spell, the 8th longest in Minneapolis records.

The National Weather Service (NWS) notes that the approaching storm is similar to the one on Nov. 10, 1998, which brought the record lowest pressure reading for the state of Minnesota, 962.8 mb. The forecast map from this morning's GFS model shows a low pressure area centered over Minnesota early Tuesday afternoon with a minimum pressure of less than 960 mb. The NWS forecast discussion points out that this would be 5 to 6 standard deviations below the average. The winds associated with this storm are expected to be 30-40 mph with gusts to near 60 mph.

Images (click to enlarge): Forecast low temperatures for central Minnesota on Friday, October 29, 2010, from National Weather Service; GFS model 30-hour forecast for 1 PM CDT, October 26, 2010, from NCEP/NWS/NOAA

Seasonal Outlook

Latest seasonal forecast: Click here.


Latest 3-month temperature outlook from Climate Prediction Center/NWS/NOAA.