Monday, March 09, 2015

End of Winter Right? Not So Fast

Northern Ohio has not had a string of days above 40 degrees similar to what we will enjoy this week since the week of Christmas. That stretch went from December 22nd to December 28th (44, 52, 59, 41, 49, 54 and 47).  While it feels great as it melts off the majority of the snow cover (big piles will stay around a while), the pattern is still ripe for more cool air relative to the averages for this time of year.

To be clear, mid March sun is much stronger than mid January sun.  The average temperature for March 8th is 44 degrees. The average temperature on March 23rd is 50.  So temperatures in the 30s or lower 40s would be considered below average. It's all relative to the season in question. It's not arctic but its not considered spring.

One of the components that we use in formulating longer range outlooks of 8-14 days is the EPO.  Its a measure of the pressure patterns in the eastern Pacific Ocean (EPO region in red boxes---excuse my crude drawing). I also included the WPO which is another favor in evaluating the pressure pattern (further west) over the Pacific Ocean.



This winter (since January), high pressure has settled over Alaska and western Canada/western US while low pressure developed south northern of Hawaii. Notice the trough and cold across the eastern US.  When the EPO is negative, this favors cold and snow east; milder temps and dry west.


The EPO has bounced back positive recently.  The trough in the east and the cold have retreated north as the ridge slid east.

By the 3rd week of March, it will more than likely drop negative again which will strongly favor colder than normal temps in the east again.

I CAUTION EVERYONE. THIS DOES NOT MEAN HIGHS IN THE 10s AND 20s WITH BELOW ZERO TEMPERATURES SIMILAR TO WHAT WE SAW IN FEBRUARY!



Notice how the temperatures spike later this week (dates are on the bottom) then drop below normal starting mid week next week on the graph below. See how temperatures fall but only into the 30s.

The bottom line:  Below normal temperatures around the 20th of March means temperatures below 50 degrees.  So highs in the 30s up through the mid 40s would classify. Not arctic cold but NOT SPRING...yet.




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