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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Wednesday
• 
• High: 72 °
• Low: 59 °
• T-Storms

• Thursday
• 
• High: 73 °
• Low: 61 °
• T-Storms

• Friday
• 
• High: 73 °
• Low: 63 °
• Chance of T-Storms

• Saturday
• 
• High: 73 °
• Low: 59 °
• Chance of T-Storms

• Sunday
• 
• High: 79 °
• Low: 63 °
• Fog

Area forecast discussion 
National Weather Service New York New York 
733 am EDT Wednesday may 23 2012 


Synopsis... 
a stalled frontal boundary to the west of the region will remain 
today and eventually dissipate into tonight. High pressure starts 
building slightly southwestward from near Nova Scotia Wednesday 
night and Thursday. An upper level disturbance will pass across 
Thursday night and Friday. Low pressure passing well to the north 
will then drag a trailing cold front into the area...which will 
then stall nearby into early next week. 


&& 


Near term /until 6 PM this evening/... 
longwave ridge axis at 500mb approaches today with a smaller upper 
level low getting distorted and weakening in the Carolinas. A stalled 
frontal boundary to the west of the forecast region will serve as 
the focus for any shower or thunderstorm development as well as 
other mesoscale boundaries in the area. With higher precipitable water values of 
1.3 to 1.5 inches...moist airmass will be in place and therefore 
some locally heavy downpours can be expected from showers and 
thunderstorms that form. 


Showers have been decreasing in intensity and coverage over the 
last hour. Expecting just isolated coverage across portions of the 
western half of the forecast region early this morning. Fog has 
been patchy in coverage and is starting to thin out with daytime 
heating with a few breaks of sun. Any dense fog that has occurred 
has been brief in duration. There are still some local reductions 
below a mile but expect these to improve within the next hour. 
Otherwise rest of forecast is currently on track without much 
change to dewpoints...temps...or winds. 


Later this morning into the afternoon...expecting any fog to 
diminish but clouds keeping in a majority of the sky for the day. 
Mixing will be limited to 950 mb at most for coastal sites and 
between 900 and 950 mb for the interior. Used a mav/met blend for 
highs as this combo was within a few degrees of highs for the 
previous day. Temperatures start out pretty mild within the 60s...with 
another 5 to around 10 degrees of warming through the day. Most 
warming will be over interior spots away from the coast. Winds 
stay light but turn more southerly. 


Concerning probability of precipitation...followed NSSL WRF reflectivity fields and GFS 
ensemble. The forcing will be the other models are in pretty good 
agreement as well with their quantitative precipitation forecast fields. Instability will increase 
with daytime heating so there will be thunderstorm potential. The 
coverage is expected to be isolated to scattered for showers and 
thunderstorms...with the highest coverage across the interior areas. 


&& 


Short term /6 PM this evening through 6 PM Thursday/... 
tonight...instability drops off and so does the precipitation potential as 
front dissipates to west of the area. Upper ridge axis moves across 
area with upper level low beginning to approach from middle Atlantic. 
There will not be synoptic forcing as shown from some q vector 
divergence in the 850 to 500mb layer with a slight decrease in 
layer precipitable water values. Winds will become light and gain a greater 
eastward component as Canadian maritime high pressure starts to 
build in from the north and east. Expecting fog to develop once 
again with low levels becoming saturated and light onshore flow 
aiding moisture advection. Dense fog will be possible especially 
towards Thursday morning. Lows were taken from relatively warmer 
00z mavs which kept the city regions a few degrees warmer. 


Thursday...southeast flow increases with the strengthening of the high 
offshore from the north and east of the region. The increased 
onshore flow combined with higher cloud coverage to start out will 
allow for coastal locations to be a few degrees cooler than on 
Wednesday while interior locations away from the coast will be very 
similar to highs on Wednesday. Highs were used from both the nam12 
surface temperatures and 00z met guidance. Less of a coherent quantitative precipitation forecast signal 
amongst the numerical model guidance. Again...expecting daytime 
instability with heating especially across the interior which will 
have the higher coverage of any showers and thunderstorms. Coverage 
overall will be isolated to scattered. The scattered coverage 
increases everywhere in the forecast region by late afternoon with 
some positive vorticity advection aloft from the remnants of the upper level low moving into 
the region from the southwest. 


&& 


Long term /Thursday night through Tuesday/... 
a weakening upper low will lift NE through the area Thursday night into 
Friday...followed by building heights aloft this weekend. Meanwhile low 
pressure will remain west of the MS River Valley...with warm...muggy 
conditions developing this weekend into early next week as an upper 
ridge builds NE from the Gulf Coast states into New England. 


There are some differences in the global models...specifically with 
the magnitude of the polar vortex over eastern Canada late in the 
period...which will influence the position of a weak cold front that 
drops into the area and stalls nearby. Most guidance shows the front 
in vicinity of the area on Sat...but then the 00z GFS pushes it to the south 
on Sunday...while the 00z European model (ecmwf) keeps the boundary closer to the 
area...perhaps pushing briefly to the south Sunday night. Both lift 
the front to the NE on Monday in response to low pressure moving into 
the upper Great Lakes and nearby southern Canada. Prefer a blend of 
the 00z European model (ecmwf) with the previous forecast...with scattered...mainly diurnal 
convection through at least Sunday night and possibly into Monday...and 
very warm conditions Sat-Mon...with highs in the middle and upper 80s 
inland...and around 80 at the coast...at least 10 degrees above average. 


&& 


Aviation /12z Wednesday through Sunday/... 
a stationary front will remain just west of the airports early 
today before weakening further. 


Forecast remains a challenge early this morning. Confidence in 
timing of ceilings and visibilities remains low. 


Conditions have improved quicker than previously thought...with MVFR 
or VFR generally expected before 14z...then VFR with ceilings of 4 to 6 
kft through the afternoon. Cannot rule out an afternoon shower or 
thunderstorm...with best chance at kswf. However...all NYC metropolitan 
airports could see a shower or thunderstorm during the afternoon. Not enough 
confidence though to include at this time as coverage should be low. 


Do expect low clouds and fog to return after sunset...with IFR or 
LIFR quite possible overnight. 


As for winds...light and variable or calm early this morning 
should give way to a south/southeast 5 to 10 kts 14-16z. Local 
seabreeze enhancement is possible at kjfk during the 
afternoon...perhaps 10 to 15 kts for a short time. 


Winds lighten again after sunset. 


New York metropolitan enhanced aviation weather support... 


Detailed information...including hourly taf wind component forecasts can 
be found at: http:/www.Erh.NOAA.Gov/zny/n90 (lower case) 


Kewr fcster comments: amendments likely for ceiling and visibility. Low 
confidence forecast this morning. 


The afternoon kewr haze potential forecast is green...which implies 
slant range visibility 7sm or greater outside of cloud. 


Kjfk fcster comments: amendments likely for ceiling and visibility. Low 
confidence forecast this morning. 


Klga fcster comments: amendments likely for ceiling and visibility. Low 
confidence forecast this morning. 


Kteb fcster comments: amendments likely for ceiling and visibility. Low 
confidence forecast this morning. 


Khpn fcster comments: amendments likely for ceiling and visibility. Low 
confidence forecast this morning. 


Kisp fcster comments: amendments likely for ceiling and visibility. Low 
confidence forecast this morning. 


Outlook for 12z Thursday through sun... 
Thu-sun...possible showers and thunderstorms may lead to brief sub VFR 
conditions. Best chance for these showers or thunderstorms would be during 
the afternoon and evening. 


&& 


Marine... 
due to persistent southeast swell...still have Small Craft Advisory seas on ocean today. 
Seas drop off below Small Craft Advisory for western ocean zone by late morning and 
gradually later in the afternoon for rest of ocean zones. 00z 
wavewatch guidance matched up well with buoy observation as of 6z. This 
was used for wave heights in the short term. There will be the 
potential for some dense fog tonight into Thursday morning across 
the waters. 


Combined seas via S-SW flow and incoming S swell should remain 
below Small Craft Advisory levels from Thursday night through the weekend. Possible areas 
of fog over the waters this weekend with very high dew points in 
place. 


&& 


Hydrology... 
any rain in form of isolated to scattered showers and thunderstorms. 
Quantitative precipitation forecast amounts will vary across the region. Brief locally heavy 
downpours will be possible with thunderstorms which could cause 
localized poor drainage flooding especially if multiple 
thunderstorms move across the same area. However...most basin 
averaged amounts are less than a quarter of an inch. 


Basin average amts from isolated-scattered showers/thunderstorms from Thursday night into Sat 
afternoon range from 1/4-1/2 inch from NYC metropolitan north/west...and 
less than 1/4 inch for central/eastern portions of Long Island and 
southern CT. Local downpours of up to an inch are possible...which 
could lead to localized poor drainage flooding. 


&& 


Okx watches/warnings/advisories... 
CT...none. 
New York...none. 
New Jersey...none. 
Marine...Small Craft Advisory for hazardous seas until 11 am EDT this 
morning for anz355. 
Small Craft Advisory for hazardous seas until 6 PM EDT this 
evening for anz350-353. 


&& 


$$ 
Synopsis...Goodman/jm 
near term...jm 
short term...jm 
long term...Goodman 
aviation...precipitable water 
marine...Goodman/jm 
hydrology...Goodman/jm