High Fire Danger This Week ** ** Severe weather possible over the weekend **

Models have underestimated the depth and magnitude of cold air which invaded this weekend.  Only the ADONIS model seems to have a good grip on things and have followed it closely through Tuesday.  Just so happens I did not have to change the previous forecast for Tuesday either!

With light winds and cold air I am going 10s tonight from OKC north and east.  With dew points in the 10s there should be a nice recovery as south-southeast winds kick in Monday afternoon.  An upper ridge centered in the desert southwest will cause high clouds to ride up and over from the mountains, overspreading OK for several days to come.

It appears the ridge will scoot east right into TX for Wednesday, allowing us to switch from Northwest flow back to Southwest flow starting on Thursday.  I’m thinking when we get a more southwest flow we will get thicker masses of high clouds more often, and I have trended more cloudy on Thursday/Friday as a result.  In addition, gulf moisture will begin working into the state on Tuesday, with 50 degree dew points by Wednesday evening across the eastern half of the state.  This should allow for more mid and low clouds later in the week.

A dry line will push into western OK on Wednesday.  The DGEX wants to hold the dry line near the TX-OK border for a few days while the ECMWF and GFS push it clear into central OK.  GFS grided temps from IPS Meteostar have consistently called for a high of 87 on Thursday, and I’m buying into it.  The record high temperature for OKC is 91 back in 1991 which is unusually high for this period.  Parts of western OK may make the lower 90s.

This is where the forecast gets to be real fun.  ECMWF, DGEX and GFS are offering different solutions from run to run on what will happen.  ECMWF is now calling for a frontal passage
Friday morning, where as every run (12z, 18z, 0z) GFS had a typical continued south fetch with a warm front across Kansas, connecting to a lee side low.  Both the ECMWF and GFS 12z and 18z didn’t have any upper support until Saturday, and the main lobe passes north.  This is a change from yesterday where the GFS wanted to bring a vortmax right over Oklahoma on Sunday, causing severe weather.  Well guess what, the 0Z run comes in and has the vort max arriving Sunday again.  I’m starting to think we might have severe weather Saturday or Sunday.

The GFS, and to some extent the DGEX, have wanted to be more progressive with lows coming out of the western US, while the 0z/12z ECMWF wants to cut the low off and leave it hanging back in the eastern Pacific, a pattern we have seen numerous times this winter and may be more believable.  However, due to it’s change in the pattern from yesterday, I have tossed it’s solution out.  DGEX has a more open and wider trough while GFS has a much tighter, progressive trough.  0Z GFS picks the low up on Friday off the coast of California, and brings it east.

There is major disagreement between not only the ECMWF, but run-to-run of the GFS.  18Z had one surface low pulling out with another setting up right behind it with storms Saturday and Sunday.  New 0Z is similar.  Old 12Z had Sunday in the 60s behind a cold front.  GFS gridded temps don’t agree with MOS.  12z MOS had 60s Saturday and Sunday, gridded temps have near 80 on Saturday, with total disagreement on Sunday.  12Z had 55 Sunday, 18Z had 79 (in line with the second low winding up).   I had 84 for a high on Sunday and dropped it to 65!!  It may be more like 84 if the 0z GFS is correct.  Who knows!!!  I probably should have played the middle and gone with 72 which I almost did.  I find it hard to believe the front wouldn’t be through by Sunday though.  I can’t wait for the 0Z GFS MOS.

OKC 19/56 36/68 47/78 52/87 50/78 54/80 44/65 43/53 28/56 34/65
Wind near 20 mph: Tuesday, Thursday, Saturday.
Pops: 20% Saturday. (maybe 20% Sunday?)
Cloud cover: AAAEEBBBUB

Thanks to Putnam Reiter for a similar discussion.

more at www.okcfox.com

Greg

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