fxus61 kphi 211620 

Area forecast discussion 
National Weather Service Mount Holly New Jersey 
1220 PM EDT Sat Oct 21 2017 

high pressure centered over the area will move offshore later today 
but continue to influence our weather into Monday. A cold front 
approaching from the west is expected to approach the region on 
Tuesday. Low pressure will move along the front Tuesday night 
through Wednesday. Another low will affect the area Thursday before 
more high pressure builds in for the end of the week. 


Near term /until 6 PM this evening/... 
this afternoon...sunny. Light wind becoming southeast during 
the afternoon. High temps a couple of degrees warmer than ydy. 
Looking at the European model (ecmwf) 925 mb modeled temperatures current 
thinking is that many locations in south Jersey and Delmarva 
come close or even reach 80. This matches up better than the 
cooler GFS values based on and old rule of the 10am temperature 
+10 degrees for the afternoon high. Looks very good for 75-79 
virtually everywhere i95 corridor northwestward with support 
from the 00z/21 ec 2m temp fcst at 18z today. Effective sea 
breezing along the coast this aftn with water temps in the 
60s...which are still significantly above normal for this time 
of year. 


Short term /6 PM this evening through 6 am Sunday/... 
clear and nearly calm but patchy fog may form toward dawn Sunday, 
especially se of I-95 where shallow moisture may increase enough 
for fog. Certainly a dewy late night early morning. The fcst is 
a 50 50 blend of the GFS/NAM MOS with Countryside temps lowered 
2-3f below the blended guidance and not much above this mornings 
mins...ranging from zero to +10 of normal depending on location. 


Long term /Sunday through Friday/... 
high pressure will still be in control of the weather for Sunday and 
Monday. Moisture will begin to arrive over the area however. This 
will result in some cloudiness and areas of fog for Sunday morning 
and increasing clouds for Monday. This will likely keep temperatures 
a few degrees cooler than Saturday, but readings will still be above 
normal for this part of October. 

A slow moving front and a upper trough will arrive from the Ohio 
Valley Tuesday-Wednesday. As it approaches, it slows, as low 
pressure will be deepening across the tenn valley area. The low will 
move along the front, just west of our region Tue-Tue night. This 
should bring a period of showers and gusty winds to the area. Pops 
are mostly in the likely/low categorical range at this time. Quantitative precipitation forecast 
thru 12z Wed. Could reach 1/2 to 1 inch over much of the area. 
The latest European model (ecmwf) model does have a few spots closer to 2 inches 
of quantitative precipitation forecast however. Some of the guidance suggests that some tstms 
are also possible. We will not have tstms in the grids at this 
point, but will have to consider as we get closer to the event. 
Temperatures will be above normal Tuesday, but then fall to 
normal Wednesday as the front passes. Pops will decrease back to 
chc or slgt chc levels after the front moves offshore. 

There will still be a few sct showers around Thu as the upper low 
crosses the area. After that, high pressure with drier air is 
expected for Fri. Temperatures will be near normal for both of these 


Aviation /16z Saturday through Wednesday/... 
the following discussion is for kphl, kpne, kttn, kabe, krdg, 
kilg, kmiv, kacy and surrounding areas. 

Through today...VFR with a few cirrus, especially this afternoon. 
Light north to northeast wind trending southeast during this 

Tonight...VFR with some cirrus. The IFR St/fog may develop, 
especially southeast of I-95 toward dawn Sunday...also the river 
valleys in NE PA and NW New Jersey. 

Sunday...a little fog or stratus early...otherwise VFR, 

Sunday night and Monday...low clouds and fog are possible from 
late Sunday night into Monday morning. Otherwise...mainly VFR. 

Monday night through Tuesday night...conditions lowering to 
MVFR and IFR in showers. Isolated thunderstorms and moderate to 
heavy rain are possible on Tuesday afternoon and Tuesday 
evening, along with a south wind gusting around 25 to 30 miles per hour. 

Wednesday...conditions improving to VFR. 


winds and seas well below Small Craft Advisory criteria through tonight. 

Light north winds 5-10 kt will veer over the next 24 hours, 
becoming east around midday and then S-southeast late today and 

Seas in our coastal waters of around 2 ft through tonight. 

Sunday thru Monday...sub-sca conditions with fair weather. 
Monday night...Small Craft Advisory developing on the ocean. Chance of showers. 
Tue-Tue night...Small Craft Advisory conditions on the ocean and del Bay. Showers. 
Wed-Wed night...Small Craft Advisory on the ocean. Sub-Small Craft Advisory on del Bay. Chc showers. 


Fire weather... 
relative humidity values are likely to drop to around 25% this afternoon but 
light winds will limit the risk for a rapid rate of spread of 
any wildfires. 



The 77 we're fcstg at kmpo would tie the record of 77 - 1959. 

**Top 5 warmest October on record for phl and Abe and probably 
for rest of our forecast area** 

Our 330 am forecast for the next 7 days, then adding the 
day8-11 from ftprha GFS 2meter Max/min temps yields the 
following projections for average temperature in October. 

Phl projects warmest October on record. The 64.7 degrees 
projected average is more than 7 degrees above the October 30 
year avg of 57.5. The projected positive departure is the same 
as it is for the first 20 days of the month. 

Previous top 3 average temps for October in phl 

1. 64.5 2007 

2. 63.5 1971 

3. 62.7 1947 

To drop out of the top 3 warmest the phl avg would have to 
be 2 degrees lower than currently forecast. 

Abe 60.3 or nearly 8 degrees above the 30 year avg of 52.5. 
This is #2. 

1. 60.8 2007 

2. 60.3 2017 projected 

3. 59.5 1984 

4. 59.3 1947 

5. 58.8 1971 

The values below are the October departures from normal through 
the 20th (yesterday). 

Phl 7.2 
ilg 7.1 
Abe 8.5 
mpo 6.9 
ridge 7.7 
ttn 7.8 
Acy 7.0 
55n 5.0 
Ged 6.5 

The last two years in phl ending 10/20/17 is the warmest in the 
period of record dating back to 1872...averaging more than 3 
degrees above normal. 

Ditto Allentown, Wilmington being the warmest in their 
respective periods of record. 


44091 buoy drifted away from its mooring and was recovered. Its 
return to service date is unknown. 


Phi watches/warnings/advisories... 
New Jersey...none. 


near term...drag/Gaines 
short term...drag 
long term...O'Hara 

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