March 31, 2024 Outlook
Active April Start
From the start. If you are prone to basement flooding issues with excessive rainfall and need to take preparations. Do so ASAP. If you are in a flood prone area. Take preparation for what’s needed to limit impact.
The Flood watch encompasses the Allegheny Region and the rain will come through in multiple rounds beginning tonight and again Tuesday to Wednesday.
A look at the flood watch
This sould extend in to Southern PA as well.
If 3-5″ of rainfall, even over a 2-3 day period it’s not “could” see flooding. It’s will.
Also the severe threat Tuesday across the area. I think training non severe thunderstorms will be the biggest thing to watch.
A look at the 18z ECMWF (Euro)
Rainfall output off the 18z ECMWF
With this potential why isn’t more of south central PA in the flood watch yet..
And a look at the 18z GFS, less extreme than the ECMWF, but still flooding potential
I stopped the rainfall totals there, not because the precipitation stops, but because that’s when the models begin to transition to snowfall across the high ground.
If you saw yesterday’s post. Not much change to those snow thoughts. A few images for those thoughts
12z ECMWF
These models struggle in elevational events, but give a good range of potential. There will be factors that prevent actual totals from say reaching the 27″ output off the GFS. 1-compression during daytime hours. 2- some melting underneath will occur. Ground temps do diddly to get stickage as the upper layer chills rapidly. However once you insulate the ground, then ground temps help melt some underneath.
The core of the coldest and most unstable air comes across Thursday and even a bit more so Friday. Thursday may feature more consistent snow while Friday may see a increased afternoon action with the coldest core of the air overhead and some heavy burst. I know its Sunday, 5 days out. Things can obviously change but these NW flow events often pan out decently as to modeled. Snow lingering until Saturday a.m and the Wv high ground above 3600-4000′ holding below freezing from Wednesday PM through Saturday. Once below that range. More daytime compression, meltback below 3000′. So, more flux in depths vs accumulations there. If some of the better periods occur at night, better accumulation across the board and especially below 3000′ as well that can exceed expectations.
Winds will accompany the snowfall.
Allegheny Mountains Weather 