textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

The threat for flash flooding on Saturday afternoon and evening has increased. WPC added a SLIGHT (2/4) Risk for Excessive Rainfall south of I-78.

Small Craft Advisory extended through 8 AM.

KEY MESSAGES

1. Another round of heavy rain is on the horizon Saturday into Saturday night, which could bring the next round of flash flooding to the region. Unsettled weather continues through Sunday.

2. Fair weather is expected to return for early next week.

DISCUSSION

KEY MESSAGE 1...Another round of heavy rain is on the horizon Saturday into Saturday night, which could bring the next round of flash flooding to the region. Unsettled weather continues through Sunday.

Today will be pleasant with a cold front moving offshore with our region drying out. We will get a brief reprieve from the muggy conditions and wet weather with a rather pleasant day expected. Highs get into the upper 70s to low 80s with mostly sunny to partly cloudy skies.

Our attention now turns to Saturday afternoon and evening. An area of low pressure will move in from the southwest bringing another round of heavy rain to the region. PWATs are again expected to get near 2" mark with model soundings showing a tall and skinny CAPE profile. Warm cloud layers also will be over 10k feet AGL, indicating that any storms that move through will be quite the efficient rainfall producers. We are starting to get into range of the CAMs as well. Guidance is all over the place regarding the placement of the axis of heaviest rainfall, but some of the QPF numbers are a bit concerning. Both the NAM and the HRRR have bulls-eyes over 4" for different parts of the area. Additionally, most areas yesterday saw over an inch of rain, with the highest amounts of 4 to 6". So, we are quite saturated, making it easier to flood in most spots. Will have to see if guidance later today starts to hone in on where the heaviest rain will fall before considering any Flood Watches. However, WPC has added a Slight (2/4) Risk for Excessive Rainfall for most of area - south of I-78. The risk is certainly there for more flash flooding.

In terms of the severe weather risk, parameters (shear, instability, moisture, forcing) are all lower compared to what we saw yesterday. While a strong to severe thunderstorm can't be ruled out completely, the threat for damaging winds/tornadoes/hail is much lower compared to what we saw Thursday.

Some showers could linger through Sunday on the backside of the low but not expecting anything significant through the day.

KEY MESSAGE 2...Fair weather is expected to return for early next week.

More zonal flow with some subtle ridging moves in for the first half of the week. At the surface, high pressure will mainly be in control, resulting in dry and tranquil weather through Wednesday. Temperatures should be seasonable through this stretch. Another frontal system looks to move in towards Thursday-Friday, but too early to speculate on specific impacts.

AVIATION /13Z FRIDAY THROUGH TUESDAY/

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

This afternoon...VFR conditions expected now that the low clouds have moves offshore. Some daytime SCT Cu/Sc possible. North to Northeast winds around 10 kt will become more Easterly as the day goes on. A sea-breeze should develop late in the afternoon, resulting in more easterly winds at KACY/KMIV. Medium/high confid.

Tonight...Primarily VFR. Added some SCT lower clouds (020-025) for many sites but BKN025 for KACY as lower clouds should be pushing in ahead of the next system. Confid in this is not the best attm. Moderate confid overall.

Outlook...

Saturday through Sunday...Restrictions likely with scattered showers and thunderstorms moving through at times. Saturday evening into Saturday Night and Sunday afternoon currently are the periods that have the highest chance for rain/thunderstorms.

Sunday Night through Tuesday...VFR. No significant weather.

MARINE

Sub-SCA conditions expected through tonight. Winds out of the east/northeast around 10 to 15 kt and seas 2 to 4 feet.

Outlook...

Saturday through Tuesday...No marine headlines expected. Widespread showers and thunderstorms expected on the waters Saturday afternoon through Saturday Night.

Rip Currents...

For today, a MODERATE Risk for rip currents is in place for Ocean and Monmouth County, where north/northeast winds around 10 to 20 MPH are expected with breaking waves around 2 to 3 feet. An onshore swell with a dominant period of 9 seconds will also add to the rip current risk. For the southern NJ shore and Delaware Beaches, winds will be a bit less with slightly lower breaking waves. This will result in a LOW risk for rip currents in these locations.

For Saturday...onshore winds around 10 MPH and multiple swell groups (one of which has a 12 to 14 second period) will result in a MODERATE risk for rip currents at the Jersey Shore. Breaking waves will also be around 2 to 3 feet. For the Delaware Beaches, winds should be lower with lower breaking waves, resulting in a LOW risk for rip currents.

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

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...None. DE...None. MD...None. MARINE...None.