Following a cold front passage on Monday, temperatures will get colder than average for our area for most of the week and coming weekend.
A highly amplified jet flow will result from cold air dropping south from Canada and warm air pushing up the central US. We’ll be on the cold side of this seesaw at least through Friday.
The statistical/ensemble version of the GFS, the GEFS (Global Ensemble Forecast System) shows the configuration of the northern jet flow as well as the configuration of the southern stream for Friday at 1AM —
GEFS jet wind flow at 300 mb 1 AM Friday Notice that any phasing between the two jet flow as well as any storm development occurs well east of the US, in the Atlantic. (Click on image for a larger view.)
Things will be cold for our area, but quiet storm-wise.
As a character on a popular TV comedy series might have put it “NO STORM FOR YOU.”
Things look even quieter next week.
Then again, the current predictions of the jet configuration is a major change in the model forecasts from just a day ago. Things could always change.
Forecast Update Thurs 10:25 PM— Tonight’s models are suggesting that light mixed precipitation may start Saturday afternoon.
Earlier this week it became clear that an imminent plunge in cold air from Canada would be the ingredient for stormy winter weather here.
Monday’s GEFS Temperature forecast for Sunday
Today’s (Thursday’s) GEFS forecast for Monday morning. Temperatures will be in the minus 30s in the Midwest. (temperatures, not wind chills!) (Click on image for a larger view.)
Monday’s forecast for three storms hasn’t played out as expected— the plunge and amplification of the jet isn’t exactly what was forecast. The cold air is deeper than forecast in the Midwest and moving more south than southeast.
We had the first snow last night. Tonight into Friday’s storm will move south of us, missing us giving us a rest.
Saturday will be mostly cloudy and continued cold.
The next storm will affect us on Saturday night through Sunday. Right now, a light, mixed (sleet-freezing rain-rain) precipitation event is what is forecast with the main system moving to our south.
GEFS Sunday 1 PM Precipitation Type (PTYPE) forecast (Click on image for a larger view.)
We’ll have mostly sleet and some snow with this Saturday through Sunday system as warm air is expected to move in from the Atlantic. On Sunday, we may have our high temperature for the entire next week of about 37º! It would not take much for this forecast to change in to either a snow storm or a miss. But the models are in general agreement that it’s going to be a sleet mix with little accumulation.
The next significant storm is expected Monday night into Tuesday. This may give us 4-6 inches of snow. Of course, it’s way too early to predict accumulation.
Following the Tuesday storm, temperatures will get into the single digits at night.
Fri 07:37 AM Update — The next chance of snow for us (Monday evening into Tuesday) is about 96-108 hours in the future, still beyond the range of the short range, higher resolution models. (The shorter range, higher resolution models forecast 84-89 hours in advance at best. Many only forecast 48-60 hours in advance.)
Current operational GFS snow totals by Tuesday afternoon—
GFS snow totals by Tuesday afternoon. (Click on image for a larger view.)
The above GFS snow totals are somewhat similar to the ECMWF (European), Canadian GEM-Gobal and German ICON. Stay tuned.
Thank you to those of you who took part in my recent user feedback poll. Here are the final results:
“Users, would you like to see all updates posted to Twitter or just the major new posts (as currently done)? “
With it so close, I’m going to stay with only posting major new posts to Twitter, but with an occasional update also posting. (A slight change to the current approach I use.) The updates (such as those on this page) won’t be automatically posted to Twitter.
Thu 08:06 PM Update — Today’s GFS has joined other models (Canadian, European, ICON and GEFS) in predicting about 1-3 inches of snow here Monday night into Tuesday morning. (Unfortunately, the newer GFS v16 has not been available today due to planned maintenance of NOAA’s servers.)
Current GFS snow totals for Tuesday 10 AM (Click on image for a larger view.)
A new wrinkle for getting larger snow accumulation is going to be temperatures, which are trending somewhat warmer at certain levels of the atmosphere, especially near Philadelphia. Many areas will have a sleet/rain mix at times during the event reducing snow totals and making an accurate snow total forecast difficult. Since the storm is coming during the nighttime hours, a period of sleet or freezing rain is a possibility as temperatures near the ground may drop below freezing—
GFS Precipitation Type (PTYPE) Monday evening (Click on image for a larger view.)
A change back to snow is expected before ending Tuesday morning.
The fine structure of the thermal profile won’t be known until the day before the event. Stay tuned.
From Wednesday …
Today, several people at work asked me, ‘so where’s the snow?’
The statistical ensemble (GEFS) model continues to forecast a minor snow possibility for the overnight period from Monday into Tuesday morning. (see yesterday’s post for the precip forecast graphic; it hasn’t changed much with today’s model runs.)
The sort of thing I like to do is compare the soon-to-be-released GFS model version 16 and the current operational GFS model (version 15.2)’
(The GFS 16 is scheduled to become the operational model the first week in February.)
The soon-to-be-released GFS 16 has significant snowfall for our area, 4-7 inches—
GFS v 16 precip rate forecast for Tuesday 7 AM (Click on image for a larger view.)
The current operational GFS model has the storm a bust with little development and little snow—
GFS (current operational) forecast Tuesday 7 AM (Click on image for a larger view.)
The current Canadian Global and the European models are closer to the the low end with some snow 1-2 inches.
In the time period in question (~138 hours in the future), the statistical GEFS model is probably the one to consider most—
GEFS snow totals Tuesday morning (Click on image for a larger view.)
If that’s the case, the soon-to-be-released GFS model v16 has a serious precipitation over-prediction bias.
The fun of this is to see what happens. Stay tuned.
