Veteran’s Day 2015 storm could reach ‘Bombogenesis’
Enjoy the tranquil skies overhead today in Minnesota. Big changes are on the way for tomorrow. The Veteran's Day 'Bomb Cyclone' of 2015 is winding up and ready to roar.
-Red sky in the morning, sailor take warning. -Anonymous
Yes, those red morning skies can be a warning of inbound storms. The National Oceanic and Atmospheric Administration explains.
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Some weather headlines.
One more mild day today
Highs in the upper 50s
Temperatures 15 degrees warmer than average
Heavy rains with 1 to 2 inches-plus rainfall totals tomorrow night into Thursday
High wind watch issued for southwest Minnesota
Gusts from 40 to 60 mph Wednesday night
Rapidly deepening inbound system
Our inbound low is doing what lows tend to do this time of year. A rapid process of cyclogenesis means the low deepens quickly as it drives northeast tomorrow. Watch as the inbound low pushes the rain shield rapidly north tomorrow.
'Bomb Cyclogenesis?'
Pressure falls with our inbound low of 15 to 20 millibars in 24 hours will approach "bomb cyclogenesis" threshold of 24 millibars in 24 hours. At 45N latitude where we live, a 'bomb cyclone' need only drop 19 millibars in 24 hours to achieve "bomb" status.
Simply put, bomb cyclogenesis is the formation of an "extratropical area of low pressure in which the central barometric pressure drops at least 24 millibars in 24 hours." [1] However, it should be noted that this represents the most common case in areas that are north of 60 degrees latitude. Sanders and Gyakum, who coined the term "Bomb Cyclones" set the pressure falls needed to reach bomb status at 19 millibars in 24 hours at 45 degrees and 23 millibars in 24 hours at 55 degrees. -NOAA/UK Met Office
The Twin Cities National Weather Service elaborates on the unique climatology and storm intensity of the inbound system in today's forecast discussion. Time to feed your inner weather geek.
THE MAIN WX CONCERN WILL BE THE POWERFUL STORM SYSTEM AFFECTING A LARGE PORTION OF THE PLAINS/UPPER MIDWEST WEDNESDAY THROUGH FRIDAY MORNING.
VERY LITTLE CHG IN THE FORECAST FOR WED/THU AND FRI WITH MODELS CONSISTENT WITH A POWERFUL FALL STORM SYSTEM DEEPENING RAPIDLY LATE TONIGHT AND MOVING IT ACROSS THE PLAINS AND INTO THE UPPER MIDWEST BY THURSDAY MORNING. MODELS HAVE DEPICTED A 15-20 MB SFC
PRESSURE DROP IN A 24 HR PERIOD FROM LATE TONIGHT THRU EARLY THURSDAY MORNING.
BASED ON BOTH THE NAEFS/GEFS ENSEMBLE 85H & SFC PRESSURE RETURN INTERVALS...THE APPROXIMATE FREQUENCY OF OCCURRENCE FOR MID NOVEMBER /1979-2009/ IS OUTSIDE CLIMATOLOGY NORMALS. THEREFORE...IT IS A RARE EVENT WHICH NEEDS TO BE MONITOR CLOSELY FOR POTENTIAL IMPACTS.
THE FIRST IMPACT WILL LIKELY BE HIGH WINDS WHICH HAS THE POTENTIAL OF WIND GUSTS OF 60 MPH IN SOUTHWEST/SOUTH CENTRAL MN DURING THE PEAK OF THE STORM/S INTENSITY.
ANOTHER IMPACT WILL BE THE HEAVY RAINFALL AMOUNTS FOR MID NOVEMBER. BASED ON THE ORIENTATION OF THE SFC/UPPER LEVEL FEATURES AND DEFORMATION ZONE...A SWATH OF 1-2 INCHES OF RAIN WILL FALL ACROSS SOUTHERN MN...AND INTO WESTERN WI. MINOR DETAILS REMAIN EVIDENT IN THE CURRENT MODEL RUNS ON THE PLACEMENT OF THE HEAVIEST TOTALS. HOWEVER...WITH THESE TOTALS...
LOCALIZED FLOODING WILL BE POSSIBLE...ESPECIALLY WHERE THE DEFORMATION RAINFALL BANDS DEVELOP. IF THIS WERE A COLDER SYSTEM...WE WOULD BE TALKING ABOUT 1-2 FEET OF SNOW. TIMING IS STILL ON TRACK FOR RAIN DEVELOPING IN FAR SOUTHERN MN WEDNESDAY MORNING...
WITH THE HEAVIEST RAINFALL BETWEEN WEDNESDAY AFTERNOON THRU EARLY THURSDAY MORNING.
Winds crank up Wednesday as the feisty storm approaches. The window for heaviest rains falls between noon Wednesday and 6 a.m. Thursday. The latest storm tracks favor a slight northward jog, and that should put the Twin Cities metro in the heavy rainfall zone. One to 2 inches-plus looks increasingly likely from northwest Iowa through south central Minnesota, grazing the Twin Cities into northwestern Wisconsin.
Here's a closer look at the latest rainfall trends from NOAA's North American Mesoscale Forecast System model. Some 2- to 3-inch rainfall totals close to the metro? It's certainly possible.
Gales of November
A rapidly deepening storm means an intense pressure gradient. That means high winds. High wind watches are posted from southwest Minnesota into Nebraska and beyond for gusts of 40 to 60 mph by Wednesday night.
INCLUDING THE CITIES OF...REDWOOD FALLS...NEW ULM...ST. JAMES...
MANKATO...FAIRMONT...BLUE EARTH
401 AM CST TUE NOV 10 2015
...HIGH WIND WATCH IN EFFECT FROM WEDNESDAY EVENING THROUGH LATE WEDNESDAY NIGHT...
THE NATIONAL WEATHER SERVICE IN TWIN CITIES/CHANHASSEN HAS ISSUED A HIGH WIND WATCH...WHICH IS IN EFFECT FROM WEDNESDAY EVENING THROUGH LATE WEDNESDAY NIGHT.
* TIMING...9 PM WEDNESDAY TO 6 AM THURSDAY MORNING.
* WINDS...SUSTAINED WINDS OF 40 TO 50 MPH WITH GUSTS OF 60 MPH.
* IMPACTS...LOOSE OBJECTS WILL BE EASILY BLOWN ABOUT BY THE STRONG WINDS AND SOME LIGHT STRUCTURAL DAMAGE WILL BE POSSIBLE. SOME COMMERCIAL POWER INTERRUPTION WILL ALSO BE POSSIBLE DUE TO DOWNED POWER LINES.
November: Season of bad storms
November is notorious for intense storms across Minnesota. Here's yet another angle on the 75 year anniversary of the sudden and deadly Armistice Day Blizzard from the Minnesota Climate Working Group. The storm helped create the Twin Cities as a National Weather Service office location.
The Armistice Day Blizzard is the defining blizzard of the 20th century in Minnesota and remains the storm against which all other blizzards in this state are compared.
The storm began as a low pressure area over Colorado on the morning of November 10. The path of the storm would take it though La Crosse, Wisconsin on the 11th and then over Lake Superior by the 12th. The storm rapidly intensified as it moved northeast and caught many people off guard.
High temperatures in eastern Minnesota on Sunday, November 10th were mainly in the 40s with a 50 degree temperature at Winona. La Crosse was 52. In the Twin Cities, light rain began at dusk and continued through the night. The rain became steady, through the pre-dawn hours of Sunday, November 11. At 7am the air temperature on the roof of the Wold-Chamberlain Airport Terminal Building was 34 degrees and a visibility of 4 miles in light rain.
The Weather Bureau Daily Weather Map for 6:30am CST November 11, 1940 has the Armistice Day Storm over Iowa moving northeast.
The Weather Bureau forecast from Chicago for the morning of November 11 was for a "moderate cold wave warning". Chicago was the forecast office for Minnesota at that time. Shortly after 8am the rain began to change to a mixture of sleet, freezing rain and snow at the Twin Cities airport that continued for the rest of the morning coating trees and wires. The snow became heavy by lunchtime. Severe blowing and drifting snow quickly developed with winds that were sustained around 30 mph for the rest of the afternoon. The peak gust was 43 mph at 9:51pm. The visibility at the airport was zero to one eighth mile from noon until 11 pm. The temperature fell from 32 degrees at 8 am to 15 degrees by 3 pm.
The surface observations at the Twin Cities airport on November 11 show the how the weather deteriorated through the day.
Traffic by late afternoon in the Twin Cites was at a standstill and the result was that many people spent the night at their place of business in both downtown St. Paul and Minneapolis, or took refuge where they could. Hundreds of automobiles were abandoned, sometimes for days after the storm.
16.2 inches of snow fell from 8 am November 11 to 8 am November 12 at the Twin Cities airport. 26.6 inches of snow fell at Collegeville. It took days for the roads to be cleared and in some side roads, they were not open for traffic until near the close of the month.
Train travel was severely hampered as well with a head-on train collision near Watkins that claimed two lives. Another train traveling from Fargo to the Twin Cities made it as far as Willmar and then got stuck just east of town Monday night. The train returned to Willmar to wait out the storm. The passengers crowded around a stove in the day car and rationed food. The train eventually reached the Twin Cities on Wednesday November 13, twenty-seven hours late.
The Armistice Day storm and another devastating Blizzard on March 14-15, 1941 prompted the Weather Bureau to refine the forecast regional responsibilities; Minnesota, formerly under the jurisdiction of Chicago office, acquired responsibilities to dictate its own forecasts and procedures.
Another nice weekend
Things quiet down by this weekend once again. Temperatures return to the 50s ... a good 10 degrees above normal for mid-November. Here's a more detailed breakdown of forecast conditions this week.
Batten down the hatches tomorrow.