Tag Archives: Snow

Winter Weather

WINTER WEATHER UPDATE- TUES 9:40 PM

The latest NAM data has become available.  According to the NAM, the snow starts between 9 and 11 AM.  Total QPF falling as snow  varies by location, but in and around the city, about 0.30 inches water or about 3 inches of snow before mixing with sleet and freezing rain.

North and west of the city, QPF values falling as snow increase to about 0. 40 inches water, with an additional delay in the changeover.   About 4-5 inches possible in areas north and west of the city.

Because it’s already the third week of February,  the sun angle is high; solar insolation through clouds may reduce accumulation on dark pavement and roadways.

The changeover to sleet is expected between 4:30 and 6 PM.  An hour or two of sleet and freezing rain before changing to rain.

Most of the heavy precipitation will fall as rain, leaving a soggy mess by morning.  Temperatures are expected to stay above freezing towards morning, so additional freezing of fallen precip is not expected with this storm.

These sort of warm air over-running cold air scenarios  with cold air damming are tough to predict accurately.  Let’s see how it unfolds.

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.