griteater

Winter forecast still on track

From: https://www.wxonline.info/topics/preciptype.html "Melting snow to rain requires latent heat. This heat is taken from the surrounding air. In order to obtain substantial temperature change due to melting, it is necessary to have rather heavy amounts of precipitation falling with little or no warm advection. If this occurs, you can have heavy rain turn to heavy snow as the freezing level sinks downward due to cooling by latent heat absorption. Although this situation can occur, cases of substantial lowering of the freezing level due to melting are relatively rare because the combination of heavy precicpitation without warm air advection is rare." You may have been thinking of freezing rain (?) where there is a release of latent heat into the surrounding air when rain freezes.

Forecast update. Good luck to all!

Latest HREF Snow Totals

Probabilistic Heavy Snow and Icing Discussion - NWS Weather Prediction Center - College Park MD 325 PM EST Wed Feb 19 2020 Southern Appalachians and Mid Atlantic... Days 1-2... Guidance coming into much better agreement this afternoon in the evolution of a positively tilted upper trough and surface low affecting the Southern Appalachians and into NC/VA. Outside of the NAM, there is good consensus that mid-level WAA ahead of the upper trough will spread moisture northeast across the area atop a surface cold front which will sag into South Carolina and off the coast. At the same time, jet streak energy will merge and intensify to 170+kts as it exits near New England, leaving the diffluent RRQ atop the Carolinas, supporting ventilation to lower pressure and spawn cyclogenesis along the baroclinic zone offshore. The combination of all these features will produce widespread precipitation across the area, with cold air advection slowly transitioning p-type from rain to snow. The low-level thermal profile will be marginal, and antecedent conditions are unfavorable to snow accumulations, however, robust forcing, especially within an intensifying mid-level frontogenetic band pivoting across NC/VA will overcome these marginal conditions to produce a period of heavy snow. The most likely locations for heavy snowfall exceeding 4 inches will be in the terrain of NC/TN, with a secondary maximum possible in northeast NC where the longest duration of precipitation falling into the colder air will occur. Additionally, guidance indicates the potential for a band of snow to rotate eastward as the low pulls away Friday morning, which could also enhance snowfall locally. WPC probabilities for 4 inches are around 20% in the mountains, and 30-40% in northeast NC/far southeast VA.

I've been impressed with how consistent the NAM has been with modeled precip. Even during the big storm in Dec 18, it had various runs where it was splotchy here and there with the QPF output....not this time. I'd expect the radar to look good and consistent tomorrow.

A bump northwest with the precip on the 18z GFS....this is what models typically do close to go time with Miller A's - increase the precip on the NW side

The teleconnections don't look good for this storm let me tell ya

For the zone from the far northern upstate thru northern Mecklenburg country (north Charlotte) thru Raleigh, it's simply a tough call. The near surface above freezing layer is very shallow. Good, steady precip could knock the surface temperatures right down to 32-33...and with cold air pouring in to the system aloft right as the precip gets going good, any warm nosing there could get mitigated. Good luck to all!

It will say that Raleigh NWS knows what they're talking about! But I don't buy it for one bit

Raleigh NWS has the chance of precipitation tomorrow and tomorrow night in Greensboro at 50%. That's kind of astounding. They have Greensboro and Winston-Salem both with 1 inch of snow in the forecast. I'd take the over on that one all day long

Ha, yeah the south sinking cold air right as the precip maximizes is indeed unusual

HREF Precip Type

HREF Mean Snowfall 1st image is from this morning's 12z run......2nd image is from last night's 00z run (it still had more snow to go in eastern sections as it ends at hr48)

Headlines - Spring put on hold / Eyewall gets hit again. It's February 1989 all over again

The GEFS mean precip ticked south, just barely...matching the GFS move...they will probably lock in together now going forward

Dupage is an excellent site for the GEFS - https://weather.cod.edu/forecast/

It's weird to see the GFS that cold at the surface when it is typically quite warm there

HREF Snowfall at end of the run at hr48...still snowing in eastern 1/3 of NC

High Res Ensemble Forecast (HREF) Precip Type

Coming more in line, but man, the UKMet has been terrible with this one....and it has performed well at times for us in the past

GFS soundings are all snow at Raleigh Airport

GFS is a touch south with precip and temperatures