... A series of upper-level disturbances will pass through the region today and Sunday while high pressure builds over the Atlantic. Low pressure will pass to our southeast Monday as a strong cold front tracks southward; slated to cross the region Tuesday. High pressure will build overhead for the middle portion of next week as drier and cooler weather returns.
NEAR TERM /THROUGH TONIGHT/... A cold front will continue to drop southward across the region through tonight. Latest satellite and radar imagery show continued cloud cover across the northern tier of the CWA while showers associated with the previous MCS that was present over the Ohio Valley earlier this morning has now moved into the CWA. Most of the CAMs and HREF members signaled convection beginning to pop-up across the MD/PA border by now, which is not the case. Given the abundant cloud cover this morning in conjunction with the now stratiform shower activity, has tamed instability some. Much of the region remains capped except for northeastern MD where instability remains the best. CAPE values range between 1000-1500 J/kg in that area, which was previously thought to have the best potential for any convective activity.
The HRRR has continued to handle conditions the best through this morning and still appears to be the more favored model. The HRRR continues to signal storms developing mainly along I-66 and US-50 but has been very flip floppy in its runs on where the exactly the convection develops. The latest run, shows activity developing more over the DC metros and not Baltimore/NE MD which is the more favored area. More so, the DC area is still capped with limited instability. However, satellite imagery shows some clearing in that vicinity. Therefore, still think the best potential for any convection remains mainly for the DC metro areas and points northeast through early this evening.
Overall, uncertainty still remains with the convective potential and could see this not materializing at all. Will have to monitor conditions through this evening.
Continued PoPs for tonight as well since there will additional shortwave energy passing through. However any shower activity should be isolated to widely scattered for most of the area. Tonight will feel noticeably more humid with lows ranging from the 60s west of the Blue Ridge to the 70s for most places east of the Blue Ridge.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... High pressure offshore will prevent the front from clearing the area Sunday as it is expected to stall across the region tomorrow morning. The boundary will then lift northward as a warm front, which will keep the hot and humid conditions around. Given the continued unstable airmass, along with weak upper level shortwave advection, will result in continued chances for scattered showers and thunderstorms during the afternoon and early evening hours. However, shortwave advection is even weaker than it is today. Therefore, don't anticipate anything severe at this time although certainly not out of the question. Sunday is projected to be the warmest day, with temperatures in the upper 80s to low 90s across the region.
Tropical Storm Claudette which is currently situated over the Gulf States will continue to track across the southeastern US before tracking offshore Monday, just south of the Delmarva. Therefore, at this time, do not expect any impacts from the system across the CWA.
Meanwhile, a strong cold front will slowly approach the region from the northwest as a potent upper-level trough digs over the Great Lakes and Midwest. Timing of this system will have a significant impact on our forecast. As of now, we are leaning toward the less progressive solution that has the cold front holding off to our west through Monday night. If this solution plays out, then convection will be isolated or widely scattered Monday for most areas with perhaps more widespread convection near the Allgheny Highland late Monday/Monday night near the approaching cold front. If the front is faster, then convection will be more widespread and the threat for severe storms will increase. Will continue to monitor. At this time, leaning more towards the first solution as been the consensus over the last few days. Again if this holds true, then can expect more in terms of possible severe weather on Tuesday.
LONG TERM /TUESDAY THROUGH FRIDAY/... Long term will start with Canadian high pressure building across the region, with cooler and drier conditions and plenty of sunshine. Highs will be notably below normal for late June. Warming trend starts thereafter, but slowly, with low to mid 80s Thursday/Friday. Dry weather is most likely with the high pressure most likely to remain in control, but increasing humidity could allow something convective to pop, especially along the higher terrain, by Friday afternoon as the next system approaches. This next system may to affect the region more significantly Saturday with an increased risk of showers and thunderstorms, though timing uncertainty remains.