textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Winter Weather Advisory issued for Monroe County from midnight tonight through 10AM Friday for light freezing rain.

Marine Dense Fog Advisory reissued for the Delaware Bay and coastal waters south of Cape May. Marine Dense Fog Advisory now in effect through 6AM Friday for all marine zones.

KEY MESSAGES

1. Patchy dense fog is expected through Friday with intervals of mainly light rain/showers; light freezing rain possible for the Poconos.

2. Milder temperatures may promote possibilities for dense fog and thunderstorms this weekend.

DISCUSSION

KEY MESSAGE 1...Patchy dense fog is expected through Friday with intervals of mainly light rain/showers; light freezing rain possible for the Poconos.

Front stalled mostly to our south through the period will keep the weather cool and murky, with a wave of low pressure bringing a period of light rain arriving tonight. For the rest of the afternoon, light showers or a mist/drizzle and perhaps some dense fog will persist as the cool but very moist air mass lingers across the region with relatively light winds. The one thing in our favor is that winds may be just strong enough to prevent widespread dense fog, especially as remaining snow melts and ground temps approach air temps, but the risk will continue. Areas of fog are expected to redevelop tonight, though may not reach dense fog criteria.

Hi res forecast soundings are indicting the potential that overnight showers combined with marginally sufficient cold temperatures across the Pocono Plateau would lead to periods of light freezing rain early Friday morning. For the time being, a Winter Weather Advisory has only been issued for Monroe County, with the high elevations of the Pocono Plateau seeing the greatest potential for ice accretion early Friday morning. High elevations across Carbon County as well as northwestern New Jersey could also see a brief period of light freezing rain, but confidence is much lower for those locations at this time. The rest of the region will see all rain.

Friday will feature another day of dreary conditions as a backdoor front will have pushed through from the north and east and then remain stalled for a time over Delmarva. Expect lots of clouds with some fog, drizzle or a few showers as low clouds and moisture remain trapped below an inversion. Most of our area should see highs in the 40s.

KEY MESSAGE 2...Milder temperatures may promote possibilities for dense fog and thunderstorms this weekend.

A change in upper and surface patterns will result in milder temperatures for the weekend (especially Sunday) and into next week. These milder temperatures adjacent to the cold ocean waters will create opportunities for fog, perhaps dense fog, which could create impact travel. These conditions will be more likely close to the shore and around Delaware Bay. The milder temps may promote more possibilities for thunderstorms which could create impacts if they become strong. Confidence in this happening is low (not zero) at the time.

AVIATION /20Z THURSDAY THROUGH TUESDAY/

The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas.

Rest of today...IFR/LIFR conditions expected through the rest of the day with light showers, low clouds, and patchy fog. Light winds around 5 kt expected out of the east. Moderate confidence in extent of restrictions, with low confidence in timing and if there is any improvement through the day.

Tonight...IFR/LIFR conditions likely continue with fog and low stratus. A round of rain returns overnight with more fog toward dawn. East- northeast winds around 5 kt. Low confidence overall.

Friday...IFR conditions persist due to low clouds and possible fog. Fog may improve through the afternoon, but low clouds are expected to linger. A few showers possible.

Outlook...

Friday night... Restrictions possible with chances of showers and fog possible.

Saturday... Mostly VFR but IFR possible near the shore with fog.

Saturday night... Widespread lower conditions with fog and showers expected.

Sunday... Mostly VFR but IFR possible near the shore with fog.

Monday/Tuesday... VFR expected.

MARINE

Marine Dense Fog Advisory is in effect thru 6AM Friday for all coastal zones. Visibilities remain limited around 1 NM or less.

Otherwise, marine conditions are expected to remain below SCA criteria through Friday.

Outlook...

There may be a short period of low-end SCA wind gusts on Sat night, but other than that, no SCA flags expected. A few tstms with gusty winds possible Sun afternoon or evening but confidence in this rather low attm. Fog will likely be the biggest concern this period with Dense fog at times this weekend and into early next week.

PHI WATCHES/WARNINGS/ADVISORIES

PA...Winter Weather Advisory from midnight tonight to 10 AM EST Friday for PAZ055. NJ...None. DE...None. MD...None. MARINE...Dense Fog Advisory until 6 AM EST Friday for ANZ430-431- 450>455.