One-and-Only-One Official 4cast

(Posted THUR, 1/17/2019 @ 8:00pm EST)

Winter Event #5 will bring a bit of everything, including the coldest air of the season.  Here's what we expect:

Here's what we expect to happen: a low pressure center approaching from the WSW will move over or just south of the DMV region and a mix of rain and snow and maybe some sleet will start in the afternoon hours on Saturday, most likely in the 1-5 pm time frame. As the night moves on, precipitation will likely turn to all rain in the overnight and early Sunday morning hours and will be moderate-to-heavy at times with a potential of 1-2" of rain falling in a 12-18 hour period, which could causes some river flooding and localized flooding due to existing, albeit diminished, snow pack already in place.

Then as the low pressure center starts to move a bit more NE of the region over the Atlantic, an Arctic cold front with very cold, truly Arctic air, will move into the region starting in the late morning hours on Sunday and continuing through the night into Monday and that overall process will result in the following: temps will drop from the 40's around 9am to the 20's by around 3pm resulting in maybe 3-6 hours of snowfall on the back end of the storm.

More importantly, all of the water on the ground and on cars will likely start to freeze and it could happen fairly rapidly as the temps drop quickly from the 40's around 9 am on Sunday into the 20's by 3 pm, and continue dropping into the single digits or low teens by the overnight hours, which could result in what is effectively known as a flash freeze, which we simply don't actually get that often in this region.

And if that freezing of moisture on streets and sidewalks and bridges and overpasses and cars and trees occurs faster than the incoming 35-40 mph winds can dry it up, then the entire region might have a very slippery and dangerous scenario on its hands because temps will likely only top out at 20-25 degrees on Monday with wind chills Monday morning likely ZERO to -10 or even -20 degrees and temps will stay below freezing - way below Monday night into Tuesday morning - until at least Tuesday afternoon if not Wednesday afternoon if they don't quite get to 32 or above for highs on Tuesday.

Bottom line: this is a unique storm with the potential for some very unique and dangerous results that must be monitored carefully moving forward because the reality is this storm is about as difficult as they come in the DMV region in terms of forecasting, and it will ultimately, one way or another, present life-threatening conditions in the form of severe cold, dangerous wind chills, and possibly very dangerous icy roadways.

With that being said, stay tuned for updates on our platform of app-Web site-Facebook and Twitter and possibly even more weekend updates via our partnership with Eye on Annapolis as things evolve with this incoming storm.

The upside here, if there is one, is that most, if not all, schools across the region are already off Monday for the Martin Luther King Jr. holiday...so at least that's one less things to worry about looking ahead.


This storm will most likely impact the DMV region SAT PM (1/20) to late SUN PM in terms of precipitation but its impact will stretch into MON and beyond.


We will post our official one-and-only-one SNOWcast for this storm by 8am Friday (1/19):

  • Annapolis = 2.2"
  • Baltimore (BWI) = 2.4"
  • Dulles, VA = 4.2"
  • Washington, D.C. = 1.5"
  • Frederick, MD = 3.6"
  • Waldorf, MD = 0.3"
  • Bel Air, MD = 2.3"
  • Bowie, MD = 2.0"
  • Gaithersburg, MD = 3.2"
  • Fredericksburg, VA = 0.2"
  • North East, MD = 2.4"
  • Easton, MD = 0.3"
  • Cambridge, MD = "T"

As always, stay tuned for updates and be prepared ahead of time as you Always Stay Weather Informed!

Of course, be sure to GET OUR APP to TRACK THIS STORM AND MORE by searching the Apple/Google app store for DC MD VA WEATHER (or quick-link to the app download via m.appbuild.io/dmvweath).


Saturday, 1/19 @ 10:30am EST
We're close to kick-off time for a storm moving in from the SW and, now that some key answers have been revealed (more NOWcasting/reporting at this point than forecasting!), here are our expectations moving forward:
1. Some areas, especially well N/W of D.C. and Baltimore, will see some snow or a mix later this morning thru the early afternoon areas while most others will generally see rain (though a few flakes could initially fly for a very brief and insignificant period).
2. The low pressure center will track, more or less, right over the DMV region later today and tonight, causing most, if not all areas, to switch over to rain. And it could be moderate or even heavy at times with a small chance that some rumbles of thunder could be heard overnight or in the SUN AM hours. Total rainfall could exceed 1" in spots.
3. As the low pressure center moves NE of the DMV region tomorrow, two things will happen: temps will drop from the 40's around 8am into the 20's by 4pm (a bit later on the MD E Shore) and very strong northerly winds will kick in between 8am-12pm, at times gusting to 40-50 mph thru the rest of the day and into Monday morning.
We have repeatedly stated the greatest possible threat from this storm for the DMV region might be the possibility of a FLASH FREEZE of all water (from rain, snow, sleet) on the ground/cars/trees when truly Arctic air rushes into the region tomorrow behind this low pressure center. And we still think that's true. But the bottom line is this: there's virtually NO OBJECTIVE METHOD of accurately forecasting this up front because it'll come down to a real-time race between two things on Sunday: cold air freezing available water on all surfaces vs. high winds drying up the water before it freezes.
With the above in mind, simply stay tuned tomorrow for real-time updates on temps and conditions and plan accordingly.  Schools are all generally closed on Monday for the Martin Luther King, Jr. holiday, which helps logistically as there's no concern on whether or not this will impact schools on Monday (but Tuesday is another story, should this occur!).
Regardless of whether a FLASH FREEZE will occur or not, one thing is certain: it is going to get VERY COLD across the DMV region for 48-72 hours straight.
Low temps SUN PM/MON AM will be 5-15 degrees with high temps MON PM only 15-25. Wind chills late SUN PM and MON AM will be 0 to -10/-20 in spots and they'll remain very cold throughout Monday as winds continue gusting to 30+ mph.
Lows MON PM/TUES AM (kids back in school in most/all districts) will again be 5-15 degrees with high temps TUES PM possibly again not breaking the freezing mark in many spots, though it'll at least be sunny both days.
Then temps finally warm up on Wednesday, with highs in the 48-55 range, as a low pressure center well to the NW of the region helps draw warmer air up from the SSW.


Stay tuned for updates on this storm, more so than the norm...especially Sunday, as conditions could very easily get slippery and become dangerous in a hurry in the PM/nighttime/overnight hours with potentially icy roads and near-zero temps and below-zero wind chills.