Cold Tonight, Then Much Warmer.

Despite the chilly start to our day, the sunny skies and a westerly wind component still produced afternoon temperatures much above normal.  Notice the max/min temperature map across the state, courtesy of the OK Mesonet, and keep in mind that the normal max/min for Tulsa is 58/36 for this time of year.  The official numbers for Tulsa today have been 65/28 so quite a diurnal range.  By the way, the reason for the large spread is due to how dry the air is as relative humidity values dropped below 20% again this afternoon.

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That dry air will be re-enforced tonight as a weak boundary moves through shifting our winds back to a more NE component for the late night and early morning hours.  That will allow temperatures to again drop below normal with some of the colder valleys possibly dropping into the upper 20s but most locations in the lower 30s.  As we go through the day Friday, our winds will quickly return to a more SE to S component and with full sun, look for afternoon temperatures to rapidly climb to near 60 by noon and the mid-upper 60s for the afternoon.  Those winds will become strong and gusty by afternoon as well which means an enhanced fire danger situation once again.

Those gusty southerly winds will continue through the weekend and into the day Monday before the next cold front arrives Monday night.  That means moisture will also be returning and along with that an increase in the low level cloud cover.  Not much more than some patchy drizzle or a brief very light shower is expected by Sunday and perhaps into the day Monday until the front arrives Monday night to bring a chance of heavier showers and possibly some storms.  But, once again, the better moisture looks to be confined further east as you can see on the 7 day QPF map as we are on the western fringe of any significant rainfall.

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The increasing moisture and increasing cloud cover will also have an impact on temperatures as you can see on our forecast page.  In fact, Sunday and Monday mornings will likely start out at or above our normal daytime highs for that time of year but the clouds will keep a lid on our daytime temperatures so a relatively short thermometer for both days. The air behind the Monday night cold front does not look to be particularly cold so after a brief cool down for the middle of next week look for another quick rebound in temperatures. 

The reason for the lack of any really cold air since early in January lies in the wind pattern aloft.  Notice the upper level pattern as of Noon today where the colors represent the strongest winds, ie the jet streak, at the 500 mb level or about 18,000’ above sea level.  Notice also the system labeled in the N Pacific.  That is our next storm system and given its location, there remains considerable uncertainty regarding its strength, track, and timing as it moves across the lower 48. 

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Although it may not be as obvious to the casual observer, but another feature of note is the fact that the flow aloft is largely what we refer to as a zonal flow, that is the winds are primarily blowing from W-E.  There is very little N-S component, particularly from the far northern sections of this particular map.  It is that zonal pattern that has been a prominent feature since early January and is largely why we have been so warm since the middle of January and through February.  Systems come along in that flow from time to time to bring some cooler air back our way, but the much colder air remains bottled up in the arctic.

That pattern looks to persist for at least another two weeks as the 8-14 day outlook continues to suggest temperatures will average above normal here in Green Country.   Also, our chances for any additional moisture of consequence is not very promising for that time period either.

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So, stay tuned and check back for updates.

Dick Faurot