Weather Will

0z EPS probability of 3 inches or more. Most of the probability in DMV is associated with days 10-15.

WB winter precip maps NAM 12k at 0z.

Seems prudent to monitor the latest forecasts for icy conditions Saturday/Saturday night. No one is getting snowed in around the DMV this weekend. But what do I know, I’m just a lawyer with a weather hobby. i would also add as a fellow federal employee that while the NWS is conservative, they usually get it right within 48 hours or so of an event. They know the analogs and have in-house methodology to hone in on a forecast. Plus they have the added pressure to get it right with headquarters in their region. Believe me they want to get it correct so they don’t have to hear about it.

18Z GFS sleet map accumulation WB. The snow map is an inch or less. There are also pockets of light freezing rain accumulation.

EPS WB 12Z Probability of 3 inches or More Through the 30th.....not very impressive yet.

Latest WB 12Z EURO Freezing Rain Map

GEFS WB Probabilities of 3 inches or more through the following weekend. Most of this potential in the DMV is the result of the potential for a storm as depicted for NEXT weekend.

Worried was the wrong word choice. None of the models currently support a snow storm in our region. They do support a potentially significant icing event. 12z GFS is similar to NAM.

NAM WB 12z Freezing Rain totals through the run. Think we should now be worried about an ice storm.

GEFS WB 6Z Probabilities of snowfall 3 inches or more. Small percentages for this weekend and more optimistic next weekend and beyond compared to EPS.

0z EPS WB Probability of 3 inches or more....pretty bad and the crumbs are Day 11-15.

Sleet totals WB 18Z GFS

EPS isn't seeing much snow chances until the last week of January on this run.

EPS only has about 15 percent of Members with 2 or more inches DC north.

Yup, Trending in the wrong direction today. I am not posting a snow map because it is too depressing. Dr. No is striking again. But it is only Jan 14. Don’t panic...yet.

Hug P 8....actually about 60% of the GEFS are still acceptable outcomes for DC Northward.

Nice writeup by Sterling NWS this am. Nice because it explains it very well and why Impacts still uncertain. I do wish they would add the winter weather link back to the headlines so it would be easier to access. The North American Ensemble Forecast System (NAEFS) guidance over the last 24-48 hours (including the deterministic Global Forecast System, or GFS model) has trended steadily toward the European Center for Meteorological Weather Forecasting (ECMWF) model and its ensemble mean, lending to increasing confidence. This also slows down the timing of potential onset for wintry precipitation, which makes sense given the 1000-500 hPa mean ridge axis still overhead at 12Z (7:00AM EST) Saturday morning. For this reason, felt it prudent to remove the Slight Winter Storm Threat for the I-95 Corridor for Day 4/Friday and Friday night. The NAEFS mean prints out (liquid equivalent) precipitation amounts about a third of an inch higher than the ECMWF mean Saturday. The latter solution appears more likely especially south and east of eastern West Virginia and northern Maryland given most of the best lift will be focused further north and west. There are also questions on what percentage of this precipitation will fall as snow vs. sleet vs. freezing rain vs. plain rain. Ensemble probabilities have nudged ever so slightly lower south and east of a line from Washington DC to Charlottesville VA, but this may well be within the model noise level this far out in time. The antecedent surface high is quite strong (nearly 1050 hPa Friday as it passes to the north), but it will be transient and in a weakening state by the time precipitation arrives. Also, the high center itself is expected to be positioned a little farther north than what would be considered most favorable from a climatological standpoint (just north of the Saint Lawrence River instead of upstate New York). The parent low track will also be well to our north and west, with secondary low development unlikely until the attendant mid/upper trough axis pivots toward New Jersey and Long Island Saturday night. Although confidence continues to increase on the potential for a winter storm for parts of our area (above average confidence for this time range, in fact), it is still too early to get into specifics on timing and amounts of different precipitation types given the above listed uncertainties and the fact that this is still 4 to 5 days away.

6z WB GEFS mean an improvement over 0z. About 70 percent would give two inches or more DC north.

About 50 percent of the EPS members from 0z would give 2 or inches DCA north. Slight uptick from 12z.

6z GFS WB. Better than 0z.

Nice write up by Channel 9 DC. Sloppy weekend storm may bring wintry mischief to DC area http://www.wusa9.com/mobile/article/weather/weather-blog/weekend-storm-threat-jan-2020/65-abfb8331-1ad5-4efb-8831-edfb27dfae87

I missed that they raised the confidence level on the Day 6 timeframe. Thanks fir pointing it out. I like the concept of these maps but there should be a better way to illustrate it.

Sorry i put this in the wrong thread. The map was issued at 5pm today for the Saturday threat.

NWS is not raising the threat level or confidence yet at 5pm

Stupid Question: when there is mixed precip do you look at all three frozen precip maps—-snow, sleet, and freezing rain to figure out totals or how is it calculated?