A National Weather Service pressure gradient map from about 1 p.m. Tuesday, just a few hours before the storm reached its lowest pressure at Bigfork.
UPDATED AT 12:45 P.M.
The National Weather Service in Duluth has issued a report updating the situation withthe low-pressure records set by this strong fall storm.
Right now, it appears the new Minnesota state record-holder for lowest barometric pressure is Bigfork in northern Itasca County, which recorded a pressure reading of 955.2millibars, or 28.21 inches of mercury, at 5:13 p.m. Tuesday. (this is a slight recalculation from the earlier report of 28.20 inches of mercury; a few of the readings below have been recalculated as well)
The Minnesota State Climatology Office reported this morning that “it appearsÂ that the minumum pressure … measured at Bigfork is the new record low pressure for a non-tropical storm in the Continental US (excluding tornadoes).” For comparison, they also noted that the lowest pressure recorded in the Edmund Fitzgerald Storm was 28.95 inches, and the lowest pressure record in the Armistice Day Storm was 28.55 inches.
This storm also set local records for low pressure at Duluth and International Falls, and aÂ new Wisconsin state record set at Superior, which recorded a reading of 961.3 millibars, or 28.39 inches of mercury, at 11:15 a.m. Tuesday.
In general, the lower the pressure, the stronger the storm. A reading of 960 millibars is comparable to a Category 2 or 3 hurricane, although differences between storms up here and storms in the tropics mean we don’t see winds as strong as in hurricanes.
Here’s the full report of what the Weather Service had to say as of midday:
THIS IS A PRELIMINARY STATEMENT ON THESE PRESSURE RECORDS. HERE ISÂ WHAT WE KNOW SO FAR ABOUT THE LOW PRESSURE RECORDS SET ON OCTOBERÂ 26TH:
A FEW OF THE RECORDS HAVE BEEN RECALCULATED TO ADJUST FOR TRUE MEANÂ SEA LEVEL PRESSURE. SOME OF THE PREVIOUS VALUES WERE CALCULATEDÂ USING A STANDARD ATMOSPHERE ASSUMPTION /THE ALTIMETER SETTING AT THEÂ STATION/. THE VALUES IN MILLIBARS ARE THE ONES THAT WILL BE MOREÂ EXACT.
AN UNUSUALLY INTENSE LOW AFFECTED THE STATE OF MINNESOTA. AT 513 PMÂ CDT…THE AUTOMATED WEATHER OBSERVING SYSTEM AT BIGFORK MINNESOTAÂ RECORDED A 955.2 MILLIBAR /28.21 INCHES/ PRESSURE. THIS BREAKS THEÂ ALL TIME MINNESOTA STATE RECORD FOR THE LOWEST OBSERVED PRESSURE.Â THE PREVIOUS RECORD WAS 962.7 MB SET ON NOVEMBER 10 1998 AT ALBERTÂ LEA AND AUSTIN IN SOUTHERN MINNESOTA.
THE RECORD WAS INITIALLYÂ BROKEN SHORTLY AFTER 10 AM AS THE LOW PASSED BY AITKIN MINNESOTA.Â HOWEVER…THE LOW CONTINUED TO INTENSIFY INTO THE AFTERNOON OVERÂ NORTH CENTRAL MINNESOTA WHERE THE RECORD PRESSURE READING WASÂ ULTIMATELY ESTABLISHED AT BIGFORK.
.DULUTH…THE LOW PRESSURE RECORD AT DULUTH WAS SET AT 1115 AMÂ WITH A PRESSURE OF 960.2 MILLIBARS /28.35 INCHES/. THE PREVIOUSÂ RECORD WAS 964.3 MILLIBARS WHICH OCCURRED ON NOVEMBER 10 1998.
.INTERNATIONAL FALLS…THE LOW PRESSURE RECORD AT INTERNATIONALÂ FALLS WAS SET AT 345 PM WITH A PRESSURE OF 956.0 MILLIBARS /28.23Â INCHES/. THE PREVIOUS RECORD WAS 971.9 MILLIBARS ON OCTOBER 10 1949.
.WISCONSIN…THE LOW PRESSURE RECORD FOR THE STATE OF WISCONSIN WASÂ SET IN SUPERIOR AT 1115 AM WITH A PRESSURE OF 961.3 MILLIBARSÂ /28.39 INCHES/. THE PREVIOUS RECORD WAS 963.4 MILLIBARS WHICHÂ OCCURRED AT GREEN BAY ON APRIL 3 1982.