textproduct: Philadelphia/Mt Holly

WHAT HAS CHANGED

No significant changes from previous forecast update.

KEY MESSAGES

1. An elevated risk for fire spread is possible today, but more so on Tuesday as a dry airmass will be in place.

2. Chilly temperatures Wednesday morning and Thursday morning raise frost/freeze concerns where the growing season is currently active.

DISCUSSION

KEY MESSAGE 1...An elevated risk for fire spread is possible today, but more so on Tuesday as a dry airmass will be in place.

A period of elevated fire weather conditions is possible today, but especially on Tuesday as a dry airmass infiltrates the area. MinRH values will be in the 30-40% range across much of the area this afternoon with westerly winds around 10-15 mph and gusts up to 20-25 mph. Come Tuesday morning, a secondary cold front is forecast to pass through the region. This will cause dew points to fall into the teens, resulting in a very dry airmass overhead. MinRH values for Tuesday afternoon will be in the 20-30% range with northwest winds around 15-20 mph and gusts up to 30-35 mph.

At this time, these conditions do not meet Red Flag Warning criteria today, but will be very close to exceeding criteria on Tuesday. We will be in contact with our fire weather partners later today to determine if a SPS or RFW is needed for Tuesday. While there is high confidence in meteorological conditions being met for a Red Flag Warning, rainfall from Sunday may keep 10 hour dead fuel moistures high enough to offset this threat. Most areas received around 1/4 to 1/2 of an inch of rainfall, with locally higher amounts up to 1 inch across southern Delaware and New Jersey. Nonetheless, most of the area remains in some form of a drought.

KEY MESSAGE 2...Chilly temperatures Wednesday morning and Thursday morning raise frost/freeze concerns where the growing season is currently active.

Strong Canadian 1040 mb high pressure will settle over New York State on Wednesday morning before shifting off the New England coast by Thursday morning. In wake of a cold front on Tuesday, a reinforcing shot of cold, dry air will arrive Tuesday night and linger into Wednesday night. Low temperatures will fall into the low to mid 20s to low to mid 30s for most locales, with teens in the Poconos by Wednesday morning. The growing season is currently active over Delmarva with the exception of New Castle County, DE. There is a decent chance (50-60%) for temperatures at or below freezing on Wednesday morning over Delmarva as skies will be clear and winds light. With a dry airmass overhead though, frost is not really expected even with such cold temperatures. Will need to eventually decide if a Freeze Warning is needed for areas where the growing season is active. The growing season does not expand to a more widespread area until April 11.

Temperatures will be somewhat similar for Thursday morning, but with the high shifting offshore, lows should be a few degrees warmer than Wednesday. With closer dew point depressions expected for Thursday morning, suppose more patchy frost is possible. May need a Frost Advisory on Thursday morning but there is rather high confidence in Wednesday morning being the coldest of this stretch.

A return to more normal temperatures well above freezing comes by Friday morning, continuing at least through the weekend.

AVIATION /06Z MONDAY THROUGH FRIDAY/

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

Rest of Tonight (thru 12Z)...VFR. Pesky cloud deck is slowly eroding early this morning and should be mostly clear by 08-09Z. Northwest winds around 10-15 kt with occasional gusts up to 20 kt possible. Gusts should drop off once skies scatter out. Moderate-high confidence.

Monday... VFR. Clear skies in the morning giving way to BKN skies in the afternoon as strato-cu deck moves in. CIGs should remain around 5000-7000 feet. West winds around 10-15 kt with gusts around 20 kt possible. High confidence.

Monday night...VFR with scattered clouds. West winds around 5-10 kt becoming northwest late. High confidence.

Outlook...

Tuesday...VFR. Wind gusts out of the northwest around 25 to 30 kt.

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

MARINE

The Small Craft Advisories for the Atlantic Coastal Waters from Sandy Hook NJ to Fenwick Island DE are now in effect until 10 AM today mainly due to seas lingering around 5 feet.

Northwest winds around 10-20 kt will continue to diminish this morning, before settling out of the southwest around 10-15 kt this afternoon. For tonight, southwest winds persist gradually becoming northwest around 10-15 kt behind a cold frontal passage early Tuesday morning. Seas around 2-4 feet. Fair weather expected.

Outlook...

Tuesday...SCA conditions possible mainly due to gusty northwest winds around 25 kt. Seas around 3-4 feet.

Tuesday Night through Thursday...No marine headlines expected.

Friday...SCA conditions possible due to seas around 5 feet.

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.