Area Forecast Discussion

WHAT HAS CHANGED

Level 2/5 severe t-storm risk shifted to the west out of Warren County for day one.

KEY MESSAGES

1) Severe thunderstorms capable of damaging winds and heavy rainfall remain possible on Tuesday.

DISCUSSION

Since sunrise earlier today, there has been isolated showers and storms, mainly across the high terrain. High clouds and smoke at high levels has took the edge off the heating some earlier today.

Expect activity to weaken over the next few hours. The cold front is still well to the north and west. Best area for storms to fire up late is well to the west of central PA, as noted by SPC day one outlk.

KEY MESSAGE 1: Severe thunderstorms capable of damaging winds and heavy rainfall remain possible on Tuesday.

Complex pattern for the next few days. As been the case since early Spring, models close off the low by later Wed. A winter like pattern. Also one that supports heavy rain not too far from our CWA.

Before this time, models such as the 12Z NAM drop the activity to the south of our area on Tuesday. Short range models show a lot of variation. Anything forming to our west late tonight would likely have to drop more to the south, then to the east or northeast.

More information below.

Timing and placement uncertainty grows heading into tonight with continued CAM variability concerning downstream development/propagation of Great Lakes/Ohio Valley MCS activity. The main shortwave does appear to reach CPA by Tuesday morning. The decaying? MCS or related feature and associated cloud cover could dampen severe risk into the afternoon. Hires guidance seems to suggest an eastward shift in the greatest svr/FF risk as the trough deepens over the northern Mid Atlantic. Some heavy rain potential will linger into Wednesday as the slow moving upper low pivots from northeast PA toward southern New England. Storm totals could exceed 2-3 over some parts of the northeast CWA by Thursday morning.

AVIATION /00Z TUESDAY THROUGH SATURDAY/

Complex set of TAFs for the 00Z issuance, with spotty SHRA/TSRA increasing in coverage from west to east this evening & into the overnight hours, followed by a swath of more numerous SHRA/TSRA alongside lowering cloud ceilings as a surface low moves across the region during the morning & afternoon, with gradual improvements behind the low pressure center despite spotty SHRA/TSRA and lingering low clouds bringing the potential for flight restrictions.

VFR is favored outside of any SHRA/TSRA this evening, with convective activity trending more numerous overnight (particularly north and west of KMDT/KLNS), suggesting that flight restrictions to MVFR-IFR will become more likely/persistent. A more defined cluster of showers and storms associated with the low pressure center will move west to east across our area between the early morning and late afternoon, resulting in prevailing MVFR-IFR ceiling restrictions with periodic MVFR-IFR visibility restrictions. Heating may be sufficient for strong to severe thunderstorms across eastern Pennsylvania (best chance at KMDT/KLNS), with gusty/damaging winds being the primary threat.

Behind the low pressure center, showers/storms will become more widely scattered with gradual improvements to ceiling restrictions, though confidence is low regarding the extent of prevailing VFR across our terminals during the latter half of the TAF period.

Outlook...

Wed-Fri...Improving conditions into late week with lingering -SHRA. Patchy AM fog.

Sat...Restrictions possible as chances increase for showers and perhaps some thunderstorms. Patchy AM fog.

CTP WATCHES / WARNINGS / ADVISORIES

None.