textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Severe thunderstorm and flood watches have been cancelled.

KEY MESSAGES

1) Another round of showers and thunderstorms will develop late Friday.

2) Additional rounds of showers and thunderstorms are expected on Friday night into Saturday.

3) Drier and warmer conditions return by the end of the weekend into next week.

DISCUSSION

KEY MESSAGE 1...Another round of showers and thunderstorms will develop late Friday.

Storms and showers are dwindling, and the severe and flood watches have been completely cancelled. A warm and humid night on tap for the region with patchy fog developing. Lows will be in the upper 60s to low 70s.

Humid conditions continue on Friday with dew points generally in the mid 70s. With daytime temperatures in the upper 80s to low 90s, the max heat index values will be in the upper 90s, possibly touching 100.

A cold front approaches Friday afternoon, touching off another round of late day showers and thunderstorms, mainly over far western portions of the forecast area (see Key Message 2 for more).

KEY MESSAGE 2...Additional rounds of showers and thunderstorms are expected on Friday night into Saturday.

By Friday evening, convection is expected to be ongoing across the area as showers and thunderstorms develop out ahead of a cold front moving southward into the area. Similarly to Thursday, moisture is anticipated to increase ahead of the front, where PWAT values are progged to be in excess of 1.8 inches. This supports that any given shower or storm will have the ability to produce heavy rainfall and flash flooding. As of now, the majority of our forecast area is highlighted in an MARGINAL risk (Level 1/4) for excessive rainfall. Held off on expanding the Flood Watch into Friday night due to uncertainty in where the heaviest rainfall will fall today.

In terms of the severe weather threat, ML CAPE is expected to reach at least 1000 J/kg with bulk shear values around 30-35 kt. Given better frontal forcing, there looks to be another opportunity for severe weather. As of the 1730UTC/Day 2 update, SPC has upgraded the majority of our area into a MARGINAL risk (Level 1/5) for severe weather with the primary hazard being locally damaging winds.

For Saturday, there remains a bit of uncertainty with respect to frontal progression through the area but guidance has trended a bit wetter overall. We now have PoPs in the 20-50% range for area north and west of the I-95 corridor, with PoPs in the 50-80% range for areas southeast of I-95. Again, there remains a flash flood threat on Saturday, primarily for the southern half of the area, which is highlighted in a MARGINAL risk for excessive rainfall. Temperatures will mainly be in the 80s.

KEY MESSAGE 3...Drier and warmer conditions return by the end of the weekend into next week.

By Sunday and into early next week, guidance is showing an expansive upper level ridge setting up over the northern High Plains. This will yield dry weather and mainly sunny/clear skies across the majority of the Mid-Atlantic region. Temperatures will be around normal for Sunday, Monday and Tuesday, but will swing back above normal for Wednesday and Thursday.

AVIATION /01Z FRIDAY THROUGH TUESDAY/

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

Tonight...SHRA/TSRA will taper off at KMIV/KACY by 02Z. VFR, becoming MVFR or lower by or after 06Z as BR develops. Light S to nearly calm winds. Low confidence.

Friday...Primarily VFR. Another round of SHRA/TSRA may impact the terminals in the late afternoon and at night, but only included VCTS in KABE/KRDG TAFs for now. W winds 5 to 10 kt. Moderate confidence.

Outlook...

Friday night through Saturday...Prevailing VFR, however periods of sub-VFR conditions are possible. A chance for showers and thunderstorms which may cause locally gusty winds.

Saturday night through Tuesday...VFR. No significant weather expected.

MARINE

Sub-Small Craft Advisory conditions through Friday. Southwest winds around 10 to 15 kt will turn west on Friday. Seas 2 to 3 feet.

Showers and thunderstorms through this evening will result in heavy rain and potentially damaging wind gusts. VSBY restrictions in fog possible late tonight and Friday morning. Another round of showers and thunderstorms is possible late Friday afternoon.

Outlook...

Friday night through Saturday night...No marine headlines expected. Winds generally between 5-15 kt with seas around 2-3 feet.

Sunday through Sunday night...SCA conditions possible. Winds generally between 10-20 kt with seas up to 5 feet.

Monday through Tuesday...No marine headlines expected. Winds generally between 10-20 kt with seas around 3-4 feet.

Rip Currents...

For Friday, winds turn southwesterly, and the swell weakens. Thus, this should result in a LOW risk of rip currents for all beaches.

For Saturday, winds turn northerly, and the swell remains weak. Thus, this should result in a LOW risk of rip currents for all beaches.

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

PHI WATCHES/WARNINGS/ADVISORIES

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