As we head towards the final days of a mostly cold January, the Polar Vortex/East Coast trough has lifted out allowing milder Pacific air to overspread the country. This doesn't mean Winter is over, but just that it's taken a 2 week (or longer) hiatus. I often show you the upper air pattern that begins out over the Pacific and controls what happens with our weather. So let's start off the West Coast.
The Pacific remains stormy south of Alaska creating a split upper jet stream flow. The main northern jet is bringing milder Pacific air into Western Canada forcing the Arctic cold to retreat over northeast Canada.
Most of western Canada is above freezing, a big change from the below zero temps of the previous week. As the western cut-off upper low drifts to the east this week, the SW upper flow will bring in Pacific moisture to couple with the southerly (lime green arrows) low-level moisture. That will allow the southern states to enjoy a Spring preview with temps soaring into the 70s & 80s.
In fact, above-freezing temps have surged as far north as the Dakotas & Minnesota.
Currently, the southern states are in clouds limiting the warming as it's as warm up in Nebraska as in south Texas. That will change with time as we get into the warm air sector ahead of the next cold front. The top graphic is valid for Thursday at 6 PM with the cold front just entering western Louisiana.
WPC has the heaviest rains (3-5") across OK/AR with SPC outlining the severe potential over Louisiana. We'll have to watch to see if that severe risk is increased and shifted over us for Thursday night. In the short term, we have no freeze threats during the next 10-14 days and the Friday front brings us Pacific air instead of the Arctic air of last week.
There will be some dense sea fog ahead of the front for Thursday morning, but hopefully the brisk south winds will keep the fog up off the ground as a low cloud deck. Pay attention day comes Thursday after dark. Stay tuned!
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