229 FXUS61 KPHI 302339 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 639 PM EST Wed Jan 30 2019 .SYNOPSIS... Arctic air will continue to pour into the region this evening, with dangerously cold wind chills expected tonight and Thursday. A weak system may bring light snow on Friday afternoon and evening especially to southern parts of the region. High pressure returns for Saturday and Sunday with gradually moderating temperatures. By early next week, the weather may turn more unsettled with a couple of disturbances nearby, but well above average temperatures during that time. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... For the 630 PM update, temperatures and dew points are dropping a bit faster than forecast therefore these were adjusted to keep up with the trends. Given reports of blowing snow in eastern PA and northwestern NJ, added this earlier and is included through this evening. Strong winds continue, although it appears the strongest have already occurred. We will continue the Wind Advisory for now. Otherwise, bitterly cold through the night with dangerous wind chills. The wind chills are already below zero across much of the area and these will dip even lower through the night. As a result, the Wind Chill Warning continues for the Poconos with a Wind Chill Advisory elsewhere. A few record low temperatures early Thursday morning will be possible, but most spots should fall just short. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... Arctic high pressure centered over the Ohio Valley Thursday morning will shift off the Delmarva coast by sunset. Winds will only diminish slowly during the course of the day. Expect west winds 10 to 20 mph with gusts up to 25 mph. Highs will only range from the single digits across the Poconos to the low to mid 20s across southern DE. In between, teens will be the rule. Wind chills in the morning will be as low as -25 to -30 in the southern Poconos, and otherwise from around -5 to -15. By late afternoon, wind chills will struggle to get out of the single digits, and will struggle to rise above zero degrees north and west of the Fall Line. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... Overview... We remain on track for a major pattern change as we head into the end of the week and the weekend. Broad eastern US trough which has dominated the recent pattern will move away, as will the lobe of the polar vortex bringing the current Arctic blast. West Coast ridging will overspread the central and eastern US, and while losing amplitude initially it looks like it will rebuild over the East. Regardless, dramatic height rises will favor a transition to much warmer weather. The upper level changes will take time to reach the surface, however, thanks to the influence of multiple Canadian high pressure systems. Eventually, the warm air will win out and we will see well above normal temperatures by early next week. The next several days will also be marked by generally quiet weather in terms of major storminess. We will see a largely zonal, split flow regime without a lot of impact from features in either stream. A modest northern stream shortwave will likely bring some light snow Friday, and a nearby boundary could bring a couple minor precipitation threats early next week. But all in all, for this time of year, it will be a pleasantly mild and quiet period once the Arctic air pulls away. Dailies... Thursday night... The trough will be pulling away, but a large Canadian high pressure will be directly overhead. So expecting a night of good radiational cooling and another round of very cold temperatures, only slightly warmer than the prior night, though without the same level of wind chills. Single digit lows for most with readings near to below zero in the Poconos and norther NJ. Friday-Friday night... Low level Canadian high pressure remains nearby. Modest WAA in the low levels, but it will be another chilly day. We will also have a shortwave approaching from the northwest. This is not a strong disturbance and has limited lift, but some light snow is likely Friday afternoon and evening especially in central and southern parts of the area. Accumulations look to be near or below an inch. Saturday-Saturday night... A reinforcing Canadian high moves in from the northwest. We see more substantial height rises this period with growing WAA. However, the low level cold associated with the high pressure will mean temperatures, while warmer than prior days, likely still fail to reach average on Saturday. Another chilly night as well. Dry weather prevails. Sunday-Sunday night... High pressure remains nearby, and ridging begins to crest over our region. Strong temperature gradient along the northern edge of the ridge and developing low over the central US will promote cloudiness and light precipitation activity within the ridge. Presently appears most of the light precipitation should remain to our north, but enhanced cloudiness is likely with possibly some light rain or mix in northern areas. Temperatures may finally struggle up to normal on Sunday, though a wedge of low level cooler air may remain in place especially across the Poconos. Monday-Wednesday... Low pressure intensifies over the northern Plains and Great Lakes this period as strong ridging (500mb heights +1 to +2 SD) remains dominant over the East. We will get into the warm sector of the low, and with Canadian high pressure finally pulling away, this is when we will see the truly above normal temperatures. There are significant model differences on timing of features during this period. As that first low pressure moves far to our northwest, another may follow in close succession on a similar or somewhat more southeastward track. Lack of significant thermal gradients in between these features lowers confidence in timings and outcomes. Some rain showers will be possible as a weak boundary from the first low crosses by, which would probably be around Monday night or Tuesday. Temperatures by Monday climb into the 50s at least in southern NJ and Delmarva, with almost everyone seeing those values by Tuesday and near 60 degree readings possible by then in Delmarva. More rain may be possible by Wednesday if that second low develops, but confidence is low here. The main idea is that early next week looks mild, a little unsettled, but not with any major storminess or winter weather. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...VFR. West-northwest winds 15-20 knots with gusts 25-35 knots, diminishing after 05z with gusts expected to be discontinued. Thursday...VFR. West-northwest winds 10-15 knots with gusts to around 20 knots, diminishing and becoming west-southwest toward evening. OUTLOOK... Thursday night... VFR. Light NW winds. Friday-Friday night... MVFR conditions likely with areas of IFR possible Friday afternoon and evening especially near and south of PHL. Winds light from the west, becoming light and variable Friday night. VFR conditions return by midnight Friday. Saturday-Saturday night... VFR. Light west to southwest winds. Sunday-Sunday night... MVFR possible especially from TTN northward, with localized IFR also possible in these areas. PHL and southward should stay mostly VFR. Monday... MVFR or IFR possible. Low confidence. && .MARINE... As of 5 PM, issued a Freezing Spray Advisory for overnight tonight through mid-morning Thursday. Freezing spray is already developing in Delaware Bay and moderate ice accretion is expected to develop there and then spread across all waters overnight as the arctic air continues to pour into the region. Tonight...Gale-force westerly winds will persist this evening. Freezing spray is expected. Thursday...SCA expected. Freezing spray especially in the morning. Seas 3 to 5 ft. Outlook... Thursday night... SCA wind gusts possible early off northern NJ, then diminishing to sub-SCA. Seas 2 to 4 ft. Freezing spray possible. Friday-Monday... Quiet marine weather. Sub-SCA. && .CLIMATE... Record Temperatures for 1/31: Coldest Maximum Coldest Minimum Site ABE 16/1936 -9/1948 ACY 22/1966 0/1948 PHL 21/1935 3/1948 ILG 19/1935 3/1948 RDG 19/1936 -6/1905 TTN 19/1936 -1/1920 MPO 8/1920 -15/1908 GED 23/1948 1/1948 && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Wind Advisory until 10 PM EST this evening for PAZ054-055- 060>062-070-071-101>106. Wind Chill Advisory until 10 AM EST Thursday for PAZ060>062- 070-071-101>106. Wind Chill Warning until 4 PM EST Thursday for PAZ054-055. NJ...Wind Advisory until 10 PM EST this evening for NJZ001-007>010- 012>027. Wind Chill Advisory until 10 AM EST Thursday for NJZ001- 007>010-012>027. DE...Wind Advisory until 10 PM EST this evening for DEZ001>004. Wind Chill Advisory until 10 AM EST Thursday for DEZ001. Wind Chill Advisory from midnight tonight to 8 AM EST Thursday for DEZ002>004. MD...Wind Advisory until 10 PM EST this evening for MDZ008-012-015- 019-020. Wind Chill Advisory until 10 AM EST Thursday for MDZ008. Wind Chill Advisory from midnight tonight to 8 AM EST Thursday for MDZ012-015-019-020. MARINE...Freezing Spray Advisory from midnight tonight to 10 AM EST Thursday for ANZ430-431-450>455. Gale Warning until midnight EST tonight for ANZ430-431-450>455. && $$ Synopsis...O'Brien Near Term...Gorse Short Term...Kruzdlo Long Term...O'Brien Aviation...Gorse/Kruzdlo/O'Brien Marine...Gorse/Kruzdlo/O'Brien Climate...