... High pressure over the area this morning will move offshore tonight. A series of low pressure systems and a slow moving front will affect the area from late tonight through Friday. High pressure may briefly build across the area next weekend.
NEAR TERM /THROUGH TONIGHT/... High pressure moves east of the area today, allowing a light south to southeast flow to develop. This brings a slight warming trend to temperatures with highs in the mid 40s to lower 50s expected. Several waves of mid to high level clouds may limit sunshine at times.
The evening will likely start mostly clear with fairly light winds, so am expecting a quick drop in temperatures, especially in outlying areas. This poses a slightly tricky forecast overnight as overrunning moisture ahead of a low pressure system in the southern US moves toward the area. Warm advection will continue aloft while clouds thicken. Initial precipitation during the night appears to be light and intermittent rainfall, primarily focused west of I-81, although some light rain may also develop along the I-95 corridor late at night. Since temps are marginally near freezing and the slow onset to notable precipitation (giving ample time to bump up a couple degrees), any freezing rain threat is conditional, patchy, and mainly confined to areas near the Alleghenies. Since the threat probability is fairly low and confined, no advisories are being issued at this time. Lows tonight in the mid 30s to near 40.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Overrunning moisture will continue through Tuesday. While there is a fairly high chance of rain occurring across the area, it appears like it will be somewhat intermittent and light. Did trend temperatures cooler than NBM, but with established south/southeast flow, temperatures should rise into the mid 40s to lower 50s for most of the area.
This theme continues through the middle of the week as a frontal zone stretches from the Plains to the Mid Atlantic. It will be cloudy and it will rain at times, but amounts will be light. Ridging over the Gulf of Mexico may expand enough Wednesday to push the front a bit farther north, reducing rain chances somewhat and allowing temperatures to rise toward the mid 50s to mid 60s. The front may sink back into the area Wednesday night which may enhance rain chances a little.
LONG TERM /THURSDAY THROUGH SUNDAY/... Large scale ridging continues to persist over the Gulf of Mexico with a flat upper level trough extending from central Canada into the NE CONUS. Zonal flow looks to continue as a result with fairly frequent precip chances/waves traversing from west to east across the country heading into the early part of next week.
The strengthened ridge to the south combined with high pressure over eastern Canada should alleviate precipitation chances just a bit Thursday morning into Thursday afternoon. By Friday, the next cold front and area of low pressure approach the region with another round of semi-cold rain. 00z guidance continues to stand pat on a liquid p-type solution for most locations outside the mountains Friday afternoon into Saturday as colder air rushes in. The 00z GFS remains warmer compared to it's ECMWF and Canadian counterpart which would sling a mixed bag of precip as far east as I-95 late Friday night into early Saturday morning. With that said, timing will be everything in regards to the placement/passage of the low pressure wave/ front and available moisture late Thursday through Saturday morning.
Brief upper level ridging gives us a dry day on Saturday, before another wave of low pressure crosses the region Sunday and Monday. This system could bring another period of cold rain or a wintry mix pending on timing/placement of the low. Still lots of uncertainty with these two systems, so please monitor our latest forecasts over time during the upcoming week.