Category Archives: Winter Weather

Winter Weather

WINTER WEATHER UPDATE -SATURDAY

I’ve been looking at the latest GFS and NAM models from this morning. Sunday night into Tuesday promises some interesting (at least for this season) winter weather.

Two systems will affect us, one Sunday evening and the other starts Monday evening. The first approaches Sunday with light snow developing sometime during the evening and ends early morning Monday.

There are differences in the models with the QPF.  The NAM is showing 0.23 inches water, the GFS less. With the prior two winter weather events, the NAM out-performed the GFS.   So it appears that 2, possibly 3 inches of snow will have accumulated when it ends Monday morning.

Monday will be mostly cloudy as another more intense storm moves to our west.  Cold air in place at the surface with warm, moist air over-running the the cold air will result in snow initially.

The GFS has the snow starting early on Monday evening.  Critical temperatures in the upper atmosphere warm by 3-5 AM Tuesday morning, with the snow changing to sleet and freezing rain at that time.  It’s possible that 3-4 inches of snow will have accumulated before the changeover.

Surface temperatures may remain at or below freezing until 7 AM Tuesday, so things will be icy and messy Tuesday morning.

North and west of the city, the freezing rain and sleet may be prolonged into late morning.

By noon on Tuesday everything should have transitioned to all rain.   This looks messy and the temperature profiles and QPF predictions will likely change in the next few days.  Stay tuned.

Winter Weather

WINTER WEATHER OUTLOOK

[su_box title=”Weather Update Fri 8 AM” box_color=”#defcdc” title_color=”#000000″]So, yesterday’s models were significantly off about the amount of rain we had early this morning. (We had double the amount.) Can we depend on them for a 5 day forecast?

The current trend for Sunday night: the NAM maintains about a 2-3 inch brief snowfall before daybreak Monday. The GFS has very little. I’m going with the NAM at this time.

For Monday night into Tuesday, it appears it will be briefly snow changing to freezing rain and then all rain for most of the storm. The secondary low coastal formation doesn’t appear to be very strong. Stay tuned.[/su_box]

from yesterday…

As mentioned in my previous post, high pressure will move in for the weekend behind a cold front that moves through Friday morning. The frontal boundary will stall to our south.

For Saturday and most of Sunday, we will have mostly sunny skies but with temperatures below average, in the 30s.

The stalled frontal boundary will become associated with a developing low pressure system in the Midwest and will redevelop as a warm front, moving slowly north as it tries to displace the cold air at the surface.

Warm air will start to overrun the cold air with an initial weak impulse that may bring some light snow late Sunday night or before daybreak Monday.  (This looks to be very insignificant.)
[su_note note_color=”#d9f2da”]Thursday evening 2/7- Latest NAM has 1-3 inches of snow Sunday night. [/su_note]

As the warm front slowly approaches Tuesday, snow may develop Monday night into Tuesday, but it appears that it will mix with sleet and change to all rain sometime Tuesday. This is the most likely scenario.

But, there’s significant disagreement among the models with this system. While the change to all rain (after some freezing rain) is the most likely scenario, the GFS and FV3-GFS suggest a secondary low develops along the Delmarva coast, possibly allowing more snow. The Canadian model is similar but maintains much more cold air, with more snow.  The European model has a much later development into Wednesday, with the secondary low developing north in New England, giving us mostly rain.  

The Tuesday through Wednesday timeframe looks interesting.  Stay tuned.