Our next window of opportunity for some much-needed rainfall will arrive Monday during the overnight hours continuing through Tuesday morning before ending. The image below is from the latest high-resolution North American Model (NAM) and shows lines of thunder showers moving northeast toward the DC Region Monday night continuing through the morning rush hour and tapering off during the day on Tuesday.
A ridge of high pressure is still slated to build in across the western coast of North America with several chances of cold shots to descend southward out of Canada. The image below shows ridges of high pressure (orange colors) and troughs (blue colors) Monday through Halloween. As the troughs (dips in the jet stream) advance eastward we will have opportunities for some rainfall followed by much cooler weather.
The temperature anomalies coincide nicely with the ridges and troughs: notice several shots of cooler air impacting our region through Halloween.
The Global Forecast Ensembles (American) model are in fairly good agreement with the European Ensembles (EPS) showing several shots of colder air infiltrating our region through Halloween.
European Ensembles showing snowfall potential through Monday, the 6th of November (image courtesy wxbell):
-Notice the model image below is starting to build a nice snow pack across Canada
-Also over the next 10 days there is the potential for several lake effect snow events across the Great Lakes and some snow showers in the higher elevations from western Pennsylvania southward through the Appalachians.