Area forecast discussion 
National Weather Service Mount Holly New Jersey 
113 PM EDT Wednesday Oct 1 2014 


Synopsis... 
low pressure will redevelop off the New England coast through 
Thursday as high pressure over eastern Canada builds in from the 
northeast. A strong low pressure system over the central United 
States will move northeastward into Ontario by Friday and its 
associated strong cold front will move through the region Friday 
night into Saturday. High pressure will build in behind the 
departing front. Another cold front will cross the region around 
Monday. 


&& 


Near term /until 6 PM this evening/... 
next estf update we are going to continue minimal probability of precipitation mainly 
around the edges of our County Warning Area. There are showers both west and 
northeast of our area. The former should pass mostly to our west, 
while the latter is struggling to arrive in northern New Jersey. Cloud condensation level based 
cumulus are forming, so no big changes to other parameters needed. 


Upper low crossing PA/New Jersey today with moist cyclonic flow. 
Overcast skies this morning should brighten or thin a bit this 
afternoon to reveal a little sunset. 


Temperatures/winds/dews are a 50 50 blend of the 100z/1 NAM/GFS MOS. . 


&& 


Short term /6 PM this evening through 6 am Thursday/... 
there may be evening partial clearing before bl relative humidity saturates and 
develops lows clouds and possibly patchy fog. 


GFS MOS temperatures look far too cold since the low pressure system is far 
to the east and the cold air advection is weak. Used the NAM MOS temperatures for lows which 
are several degrees warmer than the GFS MOS. Even these were raised 
a degree or two. 


Dews were NAM MOS. 


Winds were a 50 50 blend of the GFS/NAM MOS 


Probability of precipitation were blended GFS/NAM MOS and lowered in the SW portion of the forecast 
area using the 21z/30 sref. 


&& 


Long term /Thursday through Tuesday/... 
an area of high pressure over the can Maritimes will nose westward over the 
area on Thursday and expect a dry day but abundant cloudiness as Ely 
flow will persist. This high will remain in place for Thursday night 
into Erly Friday with low pressure well off the CST of new eng. 


Attention then turns to the central Continental U.S. Where a potent low pressure system will 
take shape beginning Thursday night. This low will move north-northeastward and 
strengthen as it moves into or toward Ontario on Friday. 


The models all agree on the fact that this low develops and moves 
into or toward Ontario during this time frame, they differ a bit 
on the details, as should be expected. The GFS, NAM/WRF and CMC 
have a single low structure and bring the low into Ontario by 
03/18z. On the other hand, the European model (ecmwf) has a double low structure at 
03/18z and is significantly weaker at this time frame (by about 10 
mb) than any other model. 


It then is interesting that by 78 and 84 hours the European model (ecmwf) model has the 
strongest solution with the low, but it is further S and east with the 
low center than the other models. 


The cold front associated with this low will begin moving eastward and there could be 
some precipitation in western areas by sunset Fri, though confidence is low. 


Precipitation chances will increase from west to east Friday night and there are 
timing diffs with the models as well. The GFS and NAM/WRF generally keep 
the heaviest precipitation west of the I-95 corridor through daybreak Sat while 
the European model (ecmwf) and CMC are further east. The GFS then brings the heavier 
precipitation through during the morning hours while the European model (ecmwf) is about 6 hours 
faster. Then precipitation ends from SW to NE during the day behind the cold front passage 
as a wind shift from east to west-northwest brings in drier air. There is sill enough 
uncertainty in the models to keep confidence lower than average. The 
European model (ecmwf) is often too slow with frontal timing, so its interesting 
that it is the faster solution here. 


One noticeable trend in the 01/00 guidance is improvement in the 
second half of Sat, so have lowered probability of precipitation during this time for this 
forecast issuance. 


With that said, high pressure moves in behind cold front passage and Sat night through 
Monday look dry. 


Another weak cold front will cross the region on Mon, but at this time not enough 
confidence to put in poops as the European model (ecmwf) is dry while the GFS has 
some low probability of precipitation. 


On Tue, there could be some additional precip, which the models 
develop differently. The European model (ecmwf) tries to develop some from an area of 
low pressure which takes shape from some southern stream energy over the 
southeastern states and moves northeastward. The GFS has some northern stream and southern 
stream energy and possibly another weak frontal passage. Again, for now will just 
carry some low probability of precipitation. 


Temperatures will generally average near nrml, except for sun in the cold 
advection behind the strong fropa, where temperatures will average much 
below normal. 


&& 


Aviation /18z Wednesday through Monday/... 
the following discussion is for kphl, kpne, kttn, kabe, krdg, kilg, 
kmiv, kacy and surrounding areas. 


18z tafs will continue the idea of some VFR conditions this 
afternoon, but then predominately MVFR tonight into Thursday 
morning. 


This afternoon into early evening, mainly MVFR ceilings at coastal 
airports and terminals, borderline MVFR/VFR ceilings for the i95 
corridor and higher terrain airports and terminals and 
predominately VFR ceilings at krdg and kabe. Winds should be 
northeast at 5 to 10 knots. 


Tonight predicting a MVFR ceiling to reform at all airports and 
terminals, closest to IFR levels at the coast. Because of the 
predicted cig, we did not forecast that much fog and mainly at 
the more rural terminals. Winds should be light from the north. 


On Thursday we are reversing the process with a slightly slower 
improvement to VFR ceilings as moisture from New England at the MVFR 
level continues to move into the region. Winds should be slightly 
more from the north than northeast at speeds of around 10 knots. 




Outlook... 
Thursday afternoon...VFR. MDT to high confidence. 


Friday..VFR Erly. Possible MVFR west late. Rain chances late west. MDT confidence. 


Friday night...MVFR/IFR with increasing rain chances from west to east by 
daybreak. Rain could be heavy at times, with approaching cold front. MDT 
confidence, though low to MDT on frontal posn. 


Sat...MVFR/IFR early in rain, heavy at times...increasing to VFR. 
Rain ending from west to east during the mrng/afternoon. Cold front passage late morning Erly 
afternoon from west to east and wind shift from southeast to west-northwest. MDT confidence. 


&& 


Marine... 
there has been a steady rise in seas at buoy9 to near Small Craft 
Advisory conditions. Given Texas tower seas are also slowly 
rising, we will extend the Small Craft Advisory farther down the coast. 


Two weeks after restoration of a lengthy buoy 44065 outage...data 
transmission topped at 4pm this past Tuesday afternoon. Ndbc has 
been contacted and they will let US know what the problem is. 


Basically NE flow continues through tonight with maximum gusts around 20 
knots. Seas build to near 5 feet and generally 1-2 feet Delaware Bay. 




Outlook... 
Thursday...Ely flow will persist and there could be Small Craft Advisory conds once 
again, with a better chance over the northern waters. However, Thursday is a 
marginal day and the latest guidance indicates we may fall just short. 


Thursday night into Friday...Small Craft Advisory will likely be needed at some point during 
this period as seas increase ahead of an approaching cold front. 


Sat...strong cold front passage. Windshift to northwest or west-northwest. Seas will increase further 
and Small Craft Advisory will continue. Best chance for Small Craft Advisory wind during this time frame. 


&& 


Climate... 
monthly clm's have been run. 


&& 


Phi watches/warnings/advisories... 
PA...none. 
New Jersey...none. 
Delaware...none. 
Maryland...none. 
Marine...Small Craft Advisory until 6 am EDT Thursday for anz450>455. 


&& 


$$ 
Synopsis...nierenberg 
near term...drag/gigi 
short term...drag 
long term...nierenberg 
aviation...gigi/nierenberg 
marine...drag/gigi/nierenberg 
climate... 












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