textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

Aviation section updated for the 00z TAFs.

KEY MESSAGES

1. Limited risk for fire weather conditions continues through Monday.

2. Multiple systems bring rain to the area Wednesday through Thursday.

DISCUSSION

KEY MESSAGE 1...Limited risk for fire weather conditions continues through Monday.

A limited risk for increased fire spread continues on Monday with another day of low minimum RHs expected. Southwesterly flow returns to the region with the center of the high pressure moving to our east-southeast. More moisture will be advected back into our region with this flow, raising our dew points. However, high temperatures on Monday will be warmer as well. As a result, min RHs will once again be in the 25-30 percent range, particularly near and southeast of the I-95 corridor.

The breeze Monday is expected to be less than Sunday, however wind gusts will still be 20-25 mph especially from late morning through the afternoon. As a result, conditions are very marginal overall, so any statements look to be unlikely to be issued. However, if state fire weather partners indicate that fuel moistures have dried significantly since the last rainfall, then one may be needed.

KEY MESSAGE 2...Multiple systems bring rain to the area Wednesday through Thursday.

A high pressure system shifts offshore Tuesday, but the continued influence from the high will keep most of the area on the drier side. Also during this timeframe, there will be a low pressure system well to the north in Canada with a cold front sinking southeast from the Great Lakes region. Our NW areas have the potential to see an isolated shower (20-30%) late Tuesday into Tuesday night. The bulk of the rain will move in late Tuesday night into Wednesday morning and continue through the day Wednesday as the cold front sinks southeast into our area. This cold front then stalls across the region into Thursday with a wave of low pressure moving northward along the front leading to more rain on Thursday.

The timing of the precipitation and cold front will play key roles in the potential for any strong to severe thunderstorms. If the peak of the rainfall arrives Wednesday morning and Thursday morning, that may inhibit the ability for the low-levels of the atmosphere to become unstable enough for stronger storms in the afternoon. This has continued to be a trend with the latest forecast guidance. Overall, this will be more beneficial rain for the area with an isolated thunderstorm possible. In terms of the severe threat, the current trend has been for this to be limited or zero.

The NBM Probability of total rainfall from these two systems is about 30-50% for 1 inch or more for ares near and NW of the I-95 corridor. For areas southeast of the I-95 corridor, it is 20-40% for 1 inch or more of rainfall. Given how dry we have been, flooding concerns appear to be minimal with this largely being beneficial rainfall for the area.

AVIATION /00Z MONDAY THROUGH FRIDAY/

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

Tonight...VFR. West-northwest winds around 10 knots with some gusts up to 20 knots early, becoming west to southwest around 5 knots (becoming light and variable at some terminals). Moderate confidence.

Monday...VFR. Southwest winds 8-12 knots with gusts to 20 knots, with the wind gusts occurring mainly from late morning through the afternoon. Moderate confidence.

Outlook...

Monday night...VFR.

Tuesday...VFR. South-southwest winds gusting to 20-25 knots.

Tuesday night through Thursday...Restrictions through most of this period as rounds of showers with a slight chance (15-20%) of thunder at times move through. Outside of showers, low clouds and patchy fog which likely will drop conditions down to IFR. Wind gusts out of the south-southwest Tuesday night through Wednesday 15-25 knots, diminishing by Wednesday night. Winds turn more out of the northwest Wednesday night into Thursday.

Friday...VFR. A west-northwest wind gusting to 15-20 knots.

MARINE

A few wind gusts near 25 kts may continue through early this evening, particularly closer to the coast and in the backbays. Sub-SCA conditions are expected to continue through tonight with winds turning from west-northwesterly to southwesterly.

Winds and seas increase again by around midday Monday, particularly for coastal waters north of Great Egg Inlet, NJ. A new Small Craft Advisory has been issued for these waters as seas are expected to reach 5 feet with southwesterly winds right around 20-25 kts.

For coastal waters south of Great Egg Inlet, as well as the Delaware Bay, conditions are expected to remain below SCA criteria, though some wind gusts around 20 kts are possible.

Outlook...

Monday night through Tuesday...A Small Craft Advisory is in effect for the Atlantic Coastal Waters through 6 PM Tuesday for winds out of the south-southwest at 15-25 kt with gusts to 30 kt and seas of 5- 7 feet.

Tuesday night through Wednesday night...SCA conditions are expected with winds out of the south-southwest gusting to 25-30 kt and seas of 6-8 feet.

Thursday...Sub-SCA conditions for most of the day with seas starting to build to near 5 feet again Thursday evening.

Thursday night through Friday...SCA conditions expected with seas of 4-6 feet.

PHI WATCHES/WARNINGS/ADVISORIES

PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory from 11 AM Monday to 6 PM EDT Tuesday for ANZ450>452. Small Craft Advisory from 1 AM to 6 PM EDT Tuesday for ANZ453>455.