Hey all!
Now that we got one storm out of the way, we can talk a bit more about the icing potential we alluded to over the last few days for Sunday night. The models have been highlighting this potential for a few days now, behind the scenes we’ve been discussing what the data would do once it fully realized the fresh snowpack and its impact on anchoring surface temps below 32° longer.
We have seen the data over the last 12 hours do just that, with the freezing rain signature expanding in coverage and duration. Ice accretion forecasting is notoriously difficult and typically inaccurate, especially over 24 hours out. All we can do now is focus on the setup and highlight the potential, try to ignore the ice accumulation maps as they are not to be taken verbatim.. yet.
Attached is the NAM and HRRR for Sunday Night into Monday morning.
HRRR Model for Monday AM
Total Ice Accumulation: HRRR model
The HRRR is at the far extent of its accurate rain and paints a picture of heavy icing across the region and much more available moisture than the NAM, which is weaker and portrays and lighter, albeit impactful icing.
NAM Model : Monday Morning
Total Ice Accumulation NAM model
Which do we believe? Looking at some of the lower resolution but longer range models, the GFS and Euro are much like the NAM and keeps the bulk of the moisture to out North. At this time the HRRR is an outlier in its portrayal thus far, with that said- we are sold on its idea that the surface is colder and stays colder longer than other models are currently showing. If the other data jumps on board with more available moisture then a longer duration and more impactful icing event would be on the table.
For now, be prepared for icing to begin from west ti east between 5pm-7pm on Sunday night with light freezing rain or freezing drizzle lingering into Monday morning. Surfaces will be cold, and icing will commence immediately following the onset of precipitation. How long icing continues will depend on surface temps, which we believe will be stubborn to rise above 32° thanks to deep snowpack across parts of the region.
Please stay tuned as we monitor the data throughout the day for additional trends, we will update again this evening. Safe out there shoveling!
-Alex