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Office: CTP

FXUS61 KCTP 230236

Area Forecast Discussion
National Weather Service State College PA
1036 PM EDT Thu Mar 22 2018


High pressure north of the Great Lakes and a deep storm over
eastern Canada will keep a mainly dry northerly flow of air over
the region into at least the weekend. Temperatures will near to
slightly below normal.



Thin high clouds will continue to stream eastward leaving clear
to partly cloudy skies along with a moderate breeze out of the

Overnight lows generally in the 20s will average about 5-8 deg
below normal.


Some lower clouds may work into the northwest mountains and
Laurel Highlands late upper lvl winds shift
more the northwest.

Snowpack will likely have a large influence on high
temperatures Friday as well as lows Friday night.

As winds aloft shift more to the northwest on Friday and the
cold air deepens...expect more in the way of CU formation on
Friday across the area.


Model guidance continues to indicate cool and dry weather through
the weekend, as central Pa remains in region of large scale
subsidence and dry northwest flow just west of upper trough
axis. Precipitation associated with lee cyclone developing in
the Plains and streaking east through the mid MS/TN Valleys and
southern Appalachians is forecast to remain south of the area.

By early next week, model guidance shows upper level ridging
building into the region, supporting a high confidence forecast
of fair weather and moderating temperatures. The next frontal
system approaches by the middle of next week bringing the next
opportunity for precipitation.


High pressure building over the region will support VFR conds
at all airfields overnight and through Friday at most sites.

An upper level disturbance forecast to move across western PA
later Friday morning will lead to increased upslope flow into
the western and central mountains. This will bring a period of
mvfr cigs and scattered snow showers into Friday afternoon...
especially over hier elevations.


Sat-Tue...No sig wx expected.


March 20-21 Harrisburg Snowfall:

14.2" 2-day total snowfall ranked as the 3rd highest Spring
snowstorm and the 4th highest snowfall in March. (Spring POR

11.9" 1-day total snowfall set a daily snowfall record. The
previous record was 7.5" set in 1964.

15.6" month-to-date ranks 2018 as the 11th snowiest March




NEAR TERM...La Corte
LONG TERM...Steinbugl

Office: PHI FXUS61 KPHI 230125 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 925 PM EDT Thu Mar 22 2018 .SYNOPSIS... The coastal storm that affected the area will continue to move into the Canadian Maritimes through tonight where it will linger into Friday. High pressure briefly affects the area Saturday while an area of low pressure passes to our south overnight. High pressure will then build across the northeast later Sunday, then across much of the east coast through early next week. A cold front is possible for the later half of the week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Cirrus over the area has kept temperatures from falling off too much. That cirrus should scatter out late, and then temps my fall off fairly dramatically due to the combination of clear skies, light winds, and fresh snowpack. Lows tonight generally in the 20s across the region, or about 5 to 10 degrees below normal. As a result, any water on the roads from snow melt during the day could freeze leading to slippery conditions on area roads tonight into early Friday morning. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... Friday...A cold core mid level low (-18C at 700MB) and a 90M 12 hr 500mb HFC , digs quickly southeast over the region through the mid and late aftn. This will result not only in increasing low clouds, but also scattered rain and snow showers, especially along and north of the I-78 corridor through the afternoon. BTV snow squall parameters appear to be met so we'll be on the lookout. Most models are dry, and moisture could be very limited with little chance for moisture advection before this event. However, lower resolution models tend to underforecast precip with these types of clipper systems, so we have mentionable pops basically I78 north. Max temps 30s high terrain northwest, 40s elsewhere or about 10 to 15 degrees below normal. Northwest wind gusts 20 MPH. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... Any snow showers that affect the area during the daytime are expected to dissipate by the evening and lead to a dry forecast overnight. By Saturday, weak high pressure briefly affects the area, before an area of low pressure passes to our south overnight. It is expected that this low will pass far enough to our south that our area avoids another major snow event. However, several short wave/vorticity impulse are forecast to move across the area Saturday night through Sunday, while some enhanced low-mid level moisture and low-mid level lapse rates increase during the day as well. This could lead to some isolated snow showers overnight into Sunday, although it is a small chance at this time. Otherwise, a cool, breezy period is expected Saturday through Sunday. High pressure builds across the northeast Sunday, then begins to build down the east coast Sunday night. Dry conditions will return for late Sunday into Sunday night. By Monday, high pressure fully builds across the entire east coast, and remain in place through Tuesday. This will keep dry conditions across the area Monday and Tuesday. Temperatures remain below normal Monday and Tuesday, but a warming trend begins by Tuesday. Uncertainty begins to build as we move into Wednesday through Friday as there is the potential for a cold frontal passage, but there timing differences among long term models. The Canadian and ECMWF keep high pressure across the area and the cold front to our west, until they bring the frontal boundary through late Thursday into Friday. The GFS brings the cold front toward the area Wednesday and Wednesday night, then lifts an area of low pressure across the area with another frontal passage around Friday. Guidance has been reluctant to come to an agreement on a solution for the second half of the week. So we will keep a slight chance of showers in the forecast for Wednesday-Friday time period. Depending on the thermal profiles, precipitation would likely fall as rain for most areas, although some snow can't be ruled out for some areas. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...VFR with only high clouds (15000 AGL or higher) and those clear after 09z. Northwesterly winds near or below 10 KT. High confidence. Friday...VFR to start. Potential for MVFR or low VFR CIGs and rain/snow showers, especially vcnty of ABE-TTN during the afternoon. Northwest winds 5 to 15 kts with potential for gusts to 20 kts or so. High confidence. Outlook... Friday night...Becoming VFR. Slight chance of isolated snow showers early. Northwest winds gust 15-20 knots.Moderate confidence. Saturday...VFR. Northwest winds may gust 15-20 knots early in the day. High confidence. Saturday night...VFR early, may lower to MVFR overnight. North winds becoming northeast overnight and may gust 15-20 knots late. Moderate confidence. Sunday...Becoming generally VFR. Slight chance of isolated snow showers which may temporarily lower conditions. Northeast to east winds gusting 15 to 20 knots. Moderate confidence. Sunday night...Generally VFR. East winds gusting 15-20 knots. High confidence. Monday-Tuesday...Generally VFR. High confidence. && .MARINE... NW winds 15-20 kt with gusts up to 25 kt tonight. Atlantic seas will continue to slowly subside. Seas continue to run above the NWPS forecast by 2 ft. SCA continues through tonight for the Atlantic waters. Outlook... Friday night...Small Craft Advisory conditions possible. Saturday-Saturday night...Conditions expected to be below advisory levels. Sunday-Sunday night...Small Craft Advisory conditions possible. Monday-Tuesday...Conditions expected to be below advisory levels. && .CLIMATE... RTP water equivalent pcpn: MANY stations were set to missing as the pcpn amounts were far too low as melted by the system. What we KNOW. PHL: today is the 18th consecutive day of below normal temps in PHL. Looks like we could add 5 more to the string. There were several record daily maximum snowfalls set yesterday, March 21st. This occurred at Philadelphia, Wilmington and Allentown (which smashed their daily record). Atlantic City just missed the daily snowfall record. Location Record for 3/21 Actual Snowfall 3/21/18 -------- --------------- ----------------------- PHL 4.7" (1932) 6.7" ACY 5.9" (1889) 5.7" ILG 5.4" (1964) 6.7" ABE 4.3" (1964) 13.2" ACY 1 day snowfall of 5.7" ranks as the 7th highest March, single day total. Philly did not place top 10 1 or two day. Wilmington 6.7 was the 6th highest 1 day total in the historical database and the two day 8.1 was tied for 7th highest. Allentown 13.2 was the 4th largest single day total behind the 16.7 3/13/93 16.5 3/20/58 13.8 3/3/60 ABE Monthly 20.7 ranks #4 behind 1958 30.5 1993 21.6 1960 21.3 ACY monthly 9.2 ranks #5 behind\ 1969 17.6 2014 15.6 1960 13.4 1956 12.7 ILG monthly 20.3 ranks #2 behind 1958 20.3 PHL monthly 15.2 ranks #2 behind 1941 17.2 I tend to remember everything (at least vaguely) after 1950. Yearly July 1-June 30 snow year ACY 33.7 ranks # 9 well behind the record of 58.1 in 2010. What is as yet unconfirmed and may not be for several days... A new NJ state record for the month of March, may have been set this morning. This is as yet unconfirmed so we're not saying RECORD, but near record works for me...something else may turn up in the database that was overlooked. Jefferson Township 11.1 inches ydy (1.03 w.e) raised the monthly total to 44.3 inches. So far the record, as we know it, is 43.0 in 1958 Canistear Reservoir. UNOFFICIAL but as fyi... but impressive if you like snow. Finally PHL projection: March avg temp is likely to be less than Feb (41.9 which was 6.2 abv normal). For now, we're projecting 39.6 or 3.9 BELOW the normal of 43.5. We could see that avg temp rise a degree above where we have it projected. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 6 AM EDT Friday for ANZ450>452. Small Craft Advisory until 8 AM EDT Friday for ANZ453>455. && $$ Synopsis...Robertson Near Term...Drag/MPS Short Term...Drag/MPS Long Term...Robertson Aviation...Drag/Robertson/MPS Marine...Drag/Robertson/MPS Climate...
Office: PBZ FXUS61 KPBZ 230517 AAC AFDPBZ Area Forecast Discussion...UPDATED National Weather Service Pittsburgh PA 117 AM EDT Fri Mar 23 2018 .SYNOPSIS... Building high pressure should maintain mainly dry weather through the weekend. Low pressure passing well south of the region could bring a rain or snow shower to the southern border of the forecast area. && .NEAR TERM /THROUGH TODAY/... No changes to the overnight period. A weak shortwave will dig southeastward over eastern portions of the forecast area. This wave is rotating around a 500mb low that is drifting southeastward over portions of New York and New England. This will provide a period of weak cold air advection today, which should at least produce sct-bkn cu later this morning and through the afternoon. Temperatures will remain well below normal for mid March. && .SHORT TERM /TONIGHT THROUGH SUNDAY/... Models continue to trend southward with Saturday-Saturday night low pressure. Have lowered PoPs even further over my southern border. With rising heights behind exiting 500mb low, Saturday looks like a descent day across most of the FA, with just high cirrus clouds and some temperature moderation. Upper level heights continue to slowly rise on Sunday, and following some morning clouds, sunshine should make a return. Temperatures will still remain cool for mid March. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... Dry weather will continue with an upper ridge building locally. Influence of the next low pressure system will begin to be noticed by Tuesday with precipitation well in advance of the low itself. While it is likely that a cold front will move through sometime between Tuesday and Thursday, confidence on timing wasn't high enough to include likely pops at any time in the forecast so far. A warming trend is expected through the extended forecast, with temperatures finally returning to normal by Tuesday and continuing to warm into the middle of the week. && .AVIATION /05Z FRIDAY THROUGH TUESDAY/... General VFR conditions are expected through the period. Non- restrictive sct-bkn cu is expected to develop today. MVFR cigs are possible late in the forecast period at FKL and DUJ as colder air aloft will move across Lake Erie. Wind gusts should increase late this morning and continue through the afternoon, as a well mixed atmosphere will allow the stronger winds aloft to make it to the surface. Gusts of 15 to 20kts are possible at all ports. Winds will decrease around sunset. OUTLOOK... Some restrictions, mainly to ceilings, are possible south of PIT on Saturday as a system passes to our south. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$