Area forecast discussion 
National Weather Service Mount Holly New Jersey 
547 PM EST Tuesday Feb 9 2016 


Synopsis... 
low pressure will move northeast of the region late tonight and 
Wednesday. High pressure will work eastward through the region 
Thursday into Friday before giving way to an Arctic front on 
Friday night and Saturday. High pressure will build across the 
area on Sunday and Monday, then low pressure is expected to form 
along the middle Atlantic or southeast coast on Tuesday. 


&& 


Near term /until 6 am Wednesday morning/... 
530 PM update...an upper air analysis showed the leading edge of a 
stronger short wave reaching into southeastern Pennsylvania. At the 
same time, low to middle level convergence is showing up in a northwest 
to southeast orientation. This lines up very close to where a 
heavier band of snow is currently sliding northeastward across the 
Philadelphia metropolitan area. This feature should continue to shift 
northeastward with a burst of snow occurring with it. The more 
pronounced lift continues to be centered back in the vicinity of the 
lower Susquehanna valley and toward the Lehigh Valley. 


Farther south and east, despite cold enough temperatures aloft the 
boundary layer has just been to warm and that is allowing for mostly 
some rain closer to the coast and across much of Delaware-Maryland-Virginia. There are 
higher reflectivities evident in southern Delaware and this may be 
some sleet or large wet snowflakes mixing in especially given the 
more convective look. 


Some additional energy rounding the base of the trough may allow for 
renewed development from the southwest for awhile this evening, 
therefore bursts of heavier snow at times from about the Interstate 
95 corridor on north and west can be expected. The Winter Weather 
Advisory for the remaining portions of marylands Eastern Shore may 
be cancelled if trends hold in shifting more of the snow farther 
north. The highest snow amounts so far are mainly in portions of 
Chester County and therefore we will keep the warning going there, 
however we may very well fall short of warning criteria in Delaware 
County. 


&& 


Short term /6 am Wednesday morning through 6 PM Wednesday/... 
by dawn, we expect any leftover light snow to be winding down 
over northeast New Jersey with a slight chance of snow showers elsewhere. 


Temperatures will be in the upper 20s to lowers 30s across most 
of the area at rush hour. Although the snow will have ended over 
most of the region, slippery travel can be expected, particularly 
on untreated surfaces. 


Otherwise, it will be a mostly cloudy day with seasonable temperatures. 


&& 


Long term /Wednesday night through Tuesday/... 
overview...if I had to convey just one thing during this period 
it would be the coldest air of the season is expected to arrive 
this weekend. The overall pattern over North America through the 
period will be a trough across the east and a ridge across the west. 
Looks like two pieces of polar/Arctic air will works its way 
toward the northern middle-Atlantic with the first piece arriving 
this Thursday. A trough or cold front should pass through Wednesday 
night leading the way for the cold air. Weak high pressure will 
build later on Thursday and persist into Friday. As this occurs 
the middle-level trough will reload. A second front is forecast to move 
through sometime on Friday night into Saturday morning. It's 
behind this front where the coldest air of the season is 
forecast...800 mb temperatures bottoming out in the -25 to 30 degree c range. 
On Sunday behind the cold front, the center of surface high should 
be somewhere near the Ohio Valley. Because of this (will still 
have a gradient), winds will be quite noticeable. By Monday 
(presidents day), the high is forecast to shift to the eastern 
Seaboard. By Tuesday, the same feature should shift offshore 
providing a return flow before the next frontal passage. 


Temperatures...to be able to get some perspective, normals for 
kphl are basically in the low 40s and middle 20s through the period. 
That said, below normal temperatures are expected through the 
weekend. We'll start to moderate on Monday (near normal) and 
rebound further on Tuesday (above normal). Temperatures may not 
climb above freezing across most, if not all, the forecast area 
from early Thursday morning to Monday morning. Lows in the single 
digits and teens will be the rule, but on Sunday morning, 
temperatures from about 5 below to five above are possible. Highs 
in the teens and 20s through this time frame will be common. 


Precipitation...not seeing any large scale events through the 
period. Small probability of precipitation across portions of the area Wednesday night 
into Thursday. Small probability of precipitation again with the cold front Friday night 
into Saturday. Another shot on Tuesday. 


Wind and wind chills...west to northwest winds will prevail 
Wednesday night through Sunday night. A southerly component can be 
expected Monday into Tuesday. Speeds will be in the 10 to 20 range 
Wednesday night through Thursday night. They will relax on Friday 
and Friday night and ramp back up Saturday night and Sunday. Wind 
chills on Sunday morning could be in the -15 to -25 degree f 
range, coldest north and west. 


Impacts...impacts will be tied more to temperatures rather than 
precipitation. But keep in mind that any snow shower or squall can 
greatly reduce visibilities. Bitterly cold air can be anticipated 
on Sunday morning with wind chills in the -15 to -25 degree f 
range. 


&& 


Aviation /00z Wednesday through Sunday/... 
the following discussion is for kphl, kpne, kttn, kabe, krdg, 
kilg, kmiv, kacy and surrounding areas. 


Tonight...periods of snow for awhile with IFR conditions at times 
/LIFR visibilities at times during bursts of snow/, mainly for the 
terminals along I-95 and points northwest. Brief IFR is also 
possible at kmiv and kacy with more of some rain or rain/snow mix. 
After 06z, we expect gradual improvement with predominantly VFR at 
all taf sites by 12z. Winds will generally be east-northeast around 
10 knots, with a shift to the west-northwest after 06z. 


Wednesday...VFR conditions. West-northwest wind gusts to 20 to 25 
knots. 


Outlook... 
Wednesday night through thursday: mainly VFR, some brief MVFR 
restrictions in isolated snow showers and flurries. Northwest 
winds 15-25 knots with higher gusts. 


Thursday night and friday: VFR. Northwest winds, briefly becoming 
southwest on Friday...10 knots of less. 


Friday night and saturday: mainly VFR, possible MVFR restrictions 
in scattered snow showers. Northwest winds increasing Saturday 
from 15-25 knots with higher gusts. 


Sunday...VFR with diminishing northwest winds. 


&& 


Marine... 
for tonight and Wednesday...Small Craft Advisory remains in effect for the entire 
period, mainly for hazardous seas in the 4 to 7 feet range. 


Outlook... 
a gale watch will be issued for Wednesday night and Thursday. 


West to northwest winds will be increasing Wednesday night 
beneath strong cold advection and a deepening boundary layer. Per 
BUFKIT, the Transfer in the mixed layer is strong. Freezing spray 
should develop as well. 


Northwest gales are likely once again Saturday into Sunday as the 
coldest air of the season arrives, possibly as cold as the coldest 
period of last February. Moderate to heavy freezing spray rates 
should develop as well. 


&& 


Tides/coastal flooding... 
low pressure will continue to move farther out to sea and a 
trailing surface trough is expected to drift northeastward through 
our region tonight. An onshore flow is forecast to persist until 
the trough arrives and brings a shift to a westerly wind. 


The wind shift had already arrived on the upper part of 
Chesapeake Bay by late afternoon. It should work its way across 
Delaware, Delaware Bay and southern New Jersey up to about Long 
Beach island by midnight. The wind shift is expected to reach the 
northern part of the Jersey Shore late tonight. 


The persistent onshore flow into this evening along the 
oceanfront should not allow water to drain away from the coast. 
The positive tidal departures will not decrease much for this 
evening. Fortunately, the astronomical tide levels for this 
evening are about 0.6 to 1.0 foot lower than those of this 
morning. Regardless, we are anticipating another round of coastal 
flooding this evening and it should favor the minor category with 
roadway flooding expected. The onshore flow is forecast to be a 
bit more persistent along the northern part of the New Jersey 
coast and based on this afternoon's departure levels we have 
decided to issue a coastal Flood Warning for the potential for 
moderate flooding in Monmouth County and Middlesex County. 


Also, the minor flooding may have an opportunity to work its way 
up into New Castle County and Salem County, so those areas are 
under a new coastal Flood Advisory. 


It does not appear as though enough water will work its way back 
up to the tidal Delaware River to cause any flooding with the late 
night high tide, so no advisory is in effect there. 


Finally, tidal departures of about +2.5 feet are working their 
way up Chesapeake Bay. We will continue to see minor flooding 
there and the upper Eastern Shore remains under an advisory. We 
have made minor adjustments to the ending time of the advisory 
based on the times of high tide. The advisory now ends at 900 PM 
for Kent Island and points southward, and at midnight for Kent 
County and Cecil County. 


The development of the westerly wind will result in a decreasing 
potential for coastal flooding on Wednesday. 


Also, a strong northwesterly wind on Thursday may begin to get US 
close to low water advisory levels at that time as water is pushed 
away from the coast. 


&& 


Climate... 
near record cold is expected for portions of our area Sunday 
morning and by far the coldest air of the season so far. 


2015-16 so far rer 14th 


Abe 8......... -1 1979 


Acy 10........ -6 1979 


Phl 12........ +2 1979 


Ilg 12........ -4 1979 


Ridge 10........ -4-1983 


Ttn 9......... 0 1916 


Ged 13........ -7 1979 


Mpo -1........ -12 1970 


Additionally...this will be wind driven cold with many areas 
experiencing wind chill values of 15 to 20 below zero...possibly 
25 below in the hills and mountains of northwest New Jersey and 
northeast Pennsylvania. 


&& 


Phi watches/warnings/advisories... 
PA...Winter Weather Advisory until 6 am EST Wednesday for paz060- 
061-071-103>106. 
Winter Storm Warning until 6 am EST Wednesday for paz070-101- 
102. 
New Jersey...Winter Weather Advisory until 6 am EST Wednesday for 
njz008>010-012>020-026-027. 
Coastal Flood Advisory until midnight EST tonight for 
njz020>027. 
Coastal Flood Advisory from 10 PM this evening to 2 am EST 
Wednesday for njz016. 
Coastal Flood Warning until midnight EST tonight for 
njz012>014. 
Delaware...Winter Weather Advisory until 6 am EST Wednesday for dez001. 
Coastal Flood Advisory until midnight EST tonight for 
dez002>004. 
Coastal Flood Advisory from 10 PM this evening to 2 am EST 
Wednesday for dez001. 
Maryland...Winter Weather Advisory until 6 am EST Wednesday for mdz008- 
012-015. 
Coastal Flood Advisory until midnight EST tonight for mdz008- 
012. 
Coastal Flood Advisory until 9 PM EST this evening for mdz015- 
019-020. 
Marine...gale watch from Wednesday evening through Thursday afternoon 
for anz430-431-450>455. 
Small Craft Advisory until 6 PM EST Wednesday for anz450>455. 


&& 


$$ 
Synopsis...kruzdlo 
near term...gorse 
short term...franck 
long term...kruzdlo 
aviation...franck/gorse/kruzdlo 
marine...franck/kruzdlo 
tides/coastal flooding...iovino 
climate...drag 






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