textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

1. A significant warming trend will continue today and into this week. High temperatures will generally be upward of 10 to 20 degrees above normal, with low to mid 90s expected for many areas Monday through Wednesday.

2. A cold front will bring chances of showers and thunderstorms to the region Wednesday through Thursday, along with moderating temperatures closer to normal by the end of next week.

DISCUSSION

KEY MESSAGE 1...A significant warming trend will continue today and into this week. High temperatures will generally be upward of 10 to 20 degrees above normal, with low to mid 90s expected for many areas Monday through Wednesday.

An upper level ridge will continue to build into the eastern US this week, bringing a period of well above normal and summer- like temperatures. At the surface, high pressure over the western Atlantic will anchor and strengthen off the coast of the Mid Atlantic. This will result in a very warm south to southwesterly flow for several days bringing the warming trend.

Temperatures today will climb into the upper 80s to near 90 degrees inland as southwest warm advection continues. Along the immediate coast, it will generally be a good 5-10 degrees cooler with highs near 80 degrees before the sea breeze starts pushing inland. The day should feature partly cloudy skies with scattered clouds around. Not as breezy as Saturday. The vast majority of the area will remain dry, but we can't completely rule out an isolated shower or storm, as some of the CAM guidance continues to show this. The potential will be limited though due to weak forcing and relatively dry profiles. And if anything does occur though it should be limited in areal coverage and not long lasting.

Temperatures continue to climb into Monday for inland areas with mid to upper 80s for many areas, and low 90s over portions of eastern PA, inland southern NJ, and Delmarva. However the flow be more out of the south to even southeast, so they'll be more of cooling influence near the coast and even extending a bit farther inland compared to Sunday. This will keep these areas near the coast mainly in the 70s to low 80s.

Confidence is increasing that temperatures on Tuesday will get into the low-mid 90s across most of the region, outside of the immediate coastal areas and higher elevations. This is increasing the chance that areas within the I-95 urban corridor will flirt with heat advisory criteria. With diurnal mixing likely keeping higher dew points at bay during the peak of the heat in the afternoon, this is still not a high confidence setup. However, with warmer air temperatures, it will not take as much moisture to push heat indicies a few degrees higher and exceed the early season criteria in the urban areas.

The heat forecast remains a bit more uncertain for Wednesday, as a faster progression of an approaching front may bring more clouds ahead of the showers and storms, and cap temps and heat indices a bit lower. Regardless, this will still be a period of abnormally warm conditions and getting the area close to record high temperature territory Monday through Wednesday this week.

The heat looks to break by Thursday following the cold frontal passage late Wednesday. Temperatures will moderate closer to normal for the remainder of the week and into next weekend.

KEY MESSAGE 2...A cold front will bring chances of showers and thunderstorms to the region Wednesday through Thursday, along with moderating temperatures closer to normal by the end of next week.

The next few days should be mainly dry other than the limited shower/storm potential for today discussed above.

As mentioned earlier, a cold front will approach the area Wednesday and bring an end to the stretch of above normal temperatures by Thursday. Convective activity will likely accompany that front and the potential for an earlier arrival during the daytime on Wednesday may increase the potential for some stronger storms, but it remains too early for any details on specific impacts or hazards. The front looks to linger nearby or just south of the area late this week and this could keep some showers around at least into Thursday but perhaps even Friday and beyond as the overall weather pattern will be trending towards being more unsettled.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

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

Today...VFR. Winds becoming west-northwest around 12Z through 15-16Z, then shifting west to southwest around 5-10 kt. 10-20% chance of a shower or storm at all terminals after 18Z. High confidence.

Tonight...VFR. Southwest winds diminishing to 5 kts or less to locally calm. High confidence.

Outlook...

Monday through Tuesday...VFR prevailing with no significant weather expected.

Wednesday through Thursday...Sub-VFR with rain showers and thunderstorms Wednesday afternoon and evening. Rain showers may continue into the day Thursday.

MARINE

South to southwest winds 10-15 kts this morning, and seas will remain near 4-5 feet. A Small Craft Advisory remains in effect for our coastal ocean zones until 10 AM. Seas will diminish by late morning and afternoon. The coastal jet will increase again into the afternoon, but southerly winds and seas will be less than Saturday. 10-20% chance of a shower or storm nearshore, otherwise fair weather through tonight.

Outlook...

Monday...No marine hazards expected. Fair weather.

Tuesday through Wednesday...Southwest winds increase and could reach Small Craft Advisory levels by late Tuesday into Wednesday. There could also be some showers and thunderstorms over the waters by Wednesday afternoon associated with a cold front.

Thursday...Conditions expected to be back below Small Craft Advisory levels by this time but showers may linger.

Rip Currents...

Today, southwest winds will average 10 to 15 mph, but will turn south in the afternoon behind sea breezes. There will also be breaking waves of 2 to 3 feet with a 9 to 10 second period swell. As a result, there is a MODERATE risk for the development of dangerous and life threatening rip currents at the Jersey Shore and at Delaware Beaches.

On Monday, winds will be more south to southeast at 10 to 15 mph with breaking waves of 1 to 2 feet with a 7 to 8 second period swell. As a result, there is a MODERATE risk for the development of dangerous and life threatening rip currents at the Jersey Shore and a LOW risk at Delaware Beaches.

Important to note that while surface temperatures inland will be in the upper 80s today and in the upper 80s to low 90s on Monday, temperatures along the coasts will mainly be in the 70s to near 80 due to ocean temperatures in the 50s. These cold water temperatures can quickly cause hypothermia and physical incapacitation to anyone suddenly immersed in the water.

For specific beach forecasts, visit weather.gov/beach/phi

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 10 AM EDT this morning for ANZ450>455.