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fxus61 kokx 060030 
afdokx 


Area forecast discussion 
National Weather Service Upton New York 
830 PM EDT Sat Jul 5 2008 


Synopsis... 
an unsettled pattern will prevail through at least the first half 
of next week as tropical moisture interacts with weak disturbances 
along the western periphery of the Bermuda high. A diffuse frontal 
boundary just south of the tri-state area this evening will lift 
north Sunday evening. This will be the primary focus for showers 
and thunderstorms on sun. Warm and muggy conditions this weekend 
will be followed by hot weather for the middle of the week. 


&& 


Near term /until 6 am Sunday morning/... 
most of the convection has tapered off with loss of diurnal 
heating. There are still come stronger showers with embedded 
thunderstorms across central and southern New Jersey...but those should 
remain south of the County Warning Area. A few more showers are developing just 
north of Orange County...and a few showers could drop into the 
northern portion of the County Warning Area. Any other showers that pop up could 
produce a brief...heavy downpour...but would expect those to be 
isolated. Will update the package making few changes...will update 
the hourly grids and will drop probability of precipitation in the morning to slight 
chance. 


It will be muggy with overnight lows around 70. 


&& 


Short term /6 am Sunday morning through Tuesday/... 
a sub-tropopause ridge parked offshore and a cutoff low over the Ohio 
Valley will aid the development of airmass thunderstorms sun and 
Monday. A diffuse frontal boundary just south of Long Island on sun 
will lift northward as the middle and upper flow backs around to the 
SW. This will result in high precipitable water air being drawn northward around 
the western periphery of the western Atlantic ridge...once again 
posing the threat for localized heavy rainfall. 


Surface warm front dissipates to the north Sun night as surface winds 
become SW. Plenty of cloud cover cover over the next couple of days 
will limit the heating potential. Highs on sun will top out in the 
upper 70s to lower 80s...then rise into the lower and middle 80s 
on Monday. A deep-layered SW flow will send 850 mb temperatures to 16c 
plus on Monday. There may be enough drying in the mixed layer on 
Monday with a SW flow for NYC and points north and west to become partly 
sunny. 


The filling upper low begins to shear out to the NE late Monday and 
Monday night with scattered convection firing up primarily in the after. Once 
again...there looks to be a heavy rainfall threat with precipitable waters  around 2 
inches. However...weak shear and moderate cape could provide a 
pulse severe event...especially for those locations that see sun. 


Scattered convection remains in the forecast on Tuesday as the weakening 
upper trough slides across the area. Partly sunny skies on Tuesday will 
send interior locations into the lower 90s...and the middle and 
upper 80s at the coast. Potential for pulse severe thunderstorms 
will increase with a high cape...weak shear environment. 


&& 


Long term /Tuesday night through Saturday/... 
high pressure over the Atlantic will continue to provide the 
region with a southerly flow. As a result...expect warm and humid 
conditions to continue across the tri-state area. Temperatures 
through the period will climb into the upper 80s to lower 90s with 
dewpoints in the 60s to near 70. Unsettled conditions will 
continue with the threat of showers and thunderstorms Tuesday 
night through Thursday. The best chances for storms will be 
during the afternoon and evening hours. Drier weather is expected 
with slightly cooler conditions at the end of the long term period 
as high pressure builds in to the area. 


&& 


Aviation /01z Sunday through Thursday/... 
southeast winds at about 5-7 knots or less will be diminishing to l/v winds 
this evening...and winds of 3 knots or less will be expected through 
about 13z sun. S winds will be increasing to 5-10 knots late Sun 
morning through Sun afternoon. 


Main forecast challenge will be ceilings/visibilities for the overnight. 18z/05 
mav MOS guidance not indicating much in the way of low ceilings and 
fog...generally MVFR visibility at the knyc terminals and IFR visibility 
elsewhere with VFR ceilings. Since airmass is quite humid...will 
continue to carry IFR to LIFR ceilings/visibilities throughout and will amend 
if needed. 


Any low clouds and fog will dissipate Sun morning and VFR 
throughout will be expected. Coverage of thunderstorms should be a bit 
more widespread in the afternoon as middle level clouds break up as 
warm front lifts north through the region and dissipates. Sub-VFR 
ceilings/visibilities and erratic winds (up to 25-30 kt) will be likely in 
any thunderstorms. 


Outlook for 00z Monday through Wednesday... 
high pressure remains across the terminals into Wednesday. Monday through 
Wednesday will feature a chance of showers and thunderstorms as a surface 
trough develops during the day...and daytime heating increases 
instability. 


&& 


Marine... 
offshore ocean buoys (44025 and 44017) currently reporting seas 
around 2 feet. See no reason to deviate from the current state with 
a light east/southeast (5 to 10 kt) flow the next 24 hours. 


With a frontal boundary just south of the waters through 
Sunday...winds and seas will remain rather tranquil. The front 
then lifts north and washes out Sun night followed by a strengthening 
SW flow. Seas on the ocean are forecast to reach Small Craft Advisory criteria on 
Monday and remain there into Tuesday as SW winds increase to 15 to 20 knots. 


A persistent south to southwest flow will continue to dominate area 
waters through the period. Seas on the ocean will be at or above 
Small Craft Advisory level through Thursday...as a southerly swell develops. 


&& 


Hydrology... 
scattered convection will continue into Tuesday with the potential for 
localized heavy downpours. The flood threat should be isolated 
during this time period. 


&& 


Okx watches/warnings/advisories... 
CT...none. 
New York...none. 
New Jersey...none. 
Marine...none. 


&& 


$$ 
Synopsis...dw 
near term...mps 
short term...dw 
long term...British Columbia 
aviation...mps 
marine...BC/dw/mps 
hydrology...dw