Keeping an eye on rain and thunder on Saturday, meanwhile...
The roller-coaster or seesaw temperature pattern is still expected to continue into next month, but there are a number of indications from multiple global models of more serious cold air masses penetrating further into the U.S. by January and February, some of which may well include the Southeastern U.S.
Before that a big mid December WARM-UP next week to way above normal temperatures for much of the country as I’ve been Tweeting about for weeks now.
A cold front brings a quarter to half an inch of rain (on average) Saturday with an isolated strong or severe thunderstorm possible, damaging wind gust would be the primary threat but nothing widespread expected as of this writing. The bulk of the rain expected to fall before 7pm.
LOOKING FURTHER AHEAD...
From this distance Christmas looks like seasonable temps or warmer than normal. January through March look to have volatile temp swings with some real cold shots but big warm-ups in-between.
About the only forecast index unfavorable is the PNA which remains stubbornly in the negative phase (West Coast trough-SE ridge) according to the long-range global equations. A +PNA is much more favorable for serious cold in the SE U.S. The long-range consensus forecast is for it to remain negative TFN.
On the other hand projected to become favorable for polar air incursions are the -AO/NAO/WPO/EPO/+GLAAM. Also the MJO is forecast to go into at least PHASE 7 and possibly PHASE 8, a few models even suggest PHASE 1 AND 2 may eventually be reached sometime in January, favoring jet stream blocking ridges in the AK to Greenland/Scandinavia regions.
This rearranges the jet stream troughs and ridges across the Northern Hemisphere related to another Sudden Stratospheric Warming (SSW) event and splitting Stratospheric Polar Vortex (SPV):
SUMMATION:
Multiple signals from multiple models suggest a jet stream pattern change for January, which IF correct, would eventually bring real winter level cold with below-normal temperatures to much of the country. HOWEVER, it is TOO SOON to actually make that a forecast because the models have struggled with the pattern and there has already been one false alarm of such a pattern change that disappeared in later model runs. This time the signals are stronger but that doesn’t mean it has to happen. I will be skeptical for now, but it bears monitoring in the weeks ahead.
Follow me on Twitter @MellishMeterWSB.
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