Area Forecast Discussion
Issued by NWS Albany, NY

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KALY 201100 AFDALY Area Forecast Discussion National Weather Service Albany NY 700 AM EDT Tue Mar 20 2018 .SYNOPSIS... High pressure over southern Canada will continue to allow for cold temperatures today with a mostly sunny sky. A storm system organizing over the mid-Atlantic region will move off the eastern seaboard for tonight through Wednesday night, allowing for a moderate to heavy snow for areas south and east of the Capital Region. Behind this storm, dry and cold weather will continue for the remainder of the week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... As of 628 AM EDT...Strong and large 1030 hpa high pressure area is located over central Ontario and is nosing southeastward into the Northeast. This subsidence is allowing for nearly clear skies this morning, as IR satellite imagery only shows just some thin cirrus clouds across far southern areas. As a result of the clear skies and light winds in place, good radiational cooling has taken place and most areas will be starting the day in the single digits and teens, which is very cold for mid to late March. During the day today, dry weather will be in place as high pressure continues to slowly slide eastward across southern Canada. Although much of the region will see mostly sunny skies to start the day, some high clouds will be increasing from south to north throughout the day, as low pressure organizes over the mid-Atlantic states. Highs will generally be in the 30s. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
-- Changed Discussion --
Coastal Storm with Moderate to Heavy Snow to Impact Southern Areas... A complex storm system is expected to impact the region during the short-term period and there continues to be a great deal of uncertainty regarding how far north significant snowfall gets across the area. The forecast is rather low confidence and still may be subject to changes over the next 24 hours. Although low pressure will be emerging off the mid-Atlantic coast this evening, this particular area of low pressure will actually be exiting northeast with little impact on our area. As a result, it should remain dry across our region for most of the overnight hours, although mid and high level clouds will continue to be increasing from south to north. Any precip with this initial low pressure area will remain to our south. By late tonight, a large closed off upper level low will be moving from the Ohio valley towards the mid-Atlantic region. This will allow a separate area of low pressure to develop by Wednesday morning, which will be undergoing rapid development as the height falls approach the eastern seaboard for during the day on Wednesday. Strong frontogenesis looks to be in place along the coastal region, along with very strong easterly flow aloft, bringing in abundant Atlantic moisture. 850 hpa u wind will be about 3-4 STD below normal, although they will be focused more across Long Island, NYC area and into NJ. With strong ridging in place downstream, the storm will meander during the day Wednesday, before exiting off to the east on Wednesday night. The models have been showing terrible run-to-run consistency with this storm, even the vaunted ECMWF and NAM (which has grown a large underground following lately due to its handling of the recent March snowstorms). This can be expected due to the complicated handling of the movement of the closed upper level low and its subsequent surface cyclogenesis. Despite what any model says from run-to-run, we have confidence that there will be a sharp north-to-south gradient of snowfall with this storm across our area, with much of our area going from seeing little to no snowfall to seeing close to warning level snowfall over a short distance (possibly within a distance of 30 to 40 miles). Based off collaboration with neighboring offices, WPC and ensemble output, have decided this will be somewhere across the mid-Hudson Valley northeast into southern New England. Have included Dutchess and Litchfield Counties in a Winter Storm Warning for 6 to 12 inches of snow, with locally higher totals across far southeastern areas. Will continue Ulster County in a Watch, as well as southern Berkshires, in case the storm track shifts further north/west, otherwise there will be a narrow area that see Advisory level snowfall. At this point, don`t expect Advisory or Warning level snowfall to reach into the Capital Region (despite what random SREF members or odd-runs of the NAM may show), as the best frontogenesis looks to be focused closer to the coastal areas, which makes sense, as the stacked storm system will generally be sliding more eastward, as opposed to northeast, and the best lift looks to just too far away to have an impact this far north. The heaviest snowfall appears to be between Wednesday afternoon and Wednesday evening across our southeastern areas. Hi-res models suggest there should be a strong mesoscale band that will be lifting northwest into our CWA, and this will be the areas that sees snowfall rates of 1 to 3 inches per hour. With temps sufficient cold at all levels (including the boundary layer), snowfall shouldn`t have a tough time accumulating at all considering the very heavy rates. The main question will be how far north/west this band gets before it weakens and starts to return eastward, as the storm finally departs on Wednesday night. Some gusty winds of 20-30 mph can be expected across southeastern areas as well, so some blowing/drifting of snow will be possible as well. Behind the storm, dry and cold weather will continue for Thursday, with highs mainly in the 30s and lows in the teens and 20s, along with a partly cloudy sky.
-- End Changed Discussion --
&& .LONG TERM /FRIDAY THROUGH MONDAY/... Guidance is agreement there should be amplified longwave pattern in place across the CONUS as we close out the work week with a trough over the Northeast, a sharp ridge over the Plains and a large upper low moving into the Pacific Northwest. As we head through the weekend into early next week, the guidance diverges as it differs handling the movement of northern stream short wave energy. On Friday, there is agreement an upper trough with a short wave rotating through should swing over the Northeast. However, over the weekend the GFS builds the ridge in while the ECMWF has more short wave energy diving southward across eastern Canada resulting in an upper low developing over the region. either way it now appears the southern stream system which develops over the Plains should get suppressed well to the south. The GFS indicates the system should weaken significantly as it moves across the Southeastern United States. At there surface, strong cold high pressure is expected to shift southward from Hudson Bay to the Canadian Maritimes over the weekend with the ridge extending well southward resulting in fair weather across the local area for the period. Have left slight chance pops in for Saturday night and Sunday due to uncertainty in the forecast. Temperatures will continue to be cooler than normal into early next week, generally around 5 to 10 degrees below normal for late March. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
Strong high pressure centered over Ontario Canada extends southward across the local area resulting in VFR conditions across the local area. The high is expected to weaken some and retreat as a coastal low develops along the southeast/mid-Atlantic coast during the afternoon into the evening. Cirrus clouds will stream in with clouds thicken and lower at night especially late. North to northeast winds of 10 knots or less today will increase some late tonight/early Wednesday morning with gusts into the teens expected at KPSF. Outlook... Wednesday through Wednesday Night: Moderate Operational Impact. Chance of SN. Thursday through Thursday Night: No Operational Impact. NO SIG WX. Friday: Low Operational Impact. Slight Chance of SHRA...SHSN. Friday Night through Saturday: No Operational Impact. NO SIG WX.
-- End Changed Discussion --
&& .FIRE WEATHER... The Fire Weather season has officially begun across eastern New York and western New England. Despite this, snow cover is in place across much of the region, which will mitigate any potential fire weather hazards for the time being. Additional snowfall is expected late tonight through Wednesday night which will continue to prevent issues in the near future as well. High pressure over southern Canada will continue to allow for cold temperatures today with a mostly sunny sky. A storm system organizing over the mid-Atlantic region will move off the eastern seaboard for tonight through Wednesday night, allowing for a moderate to heavy snow for areas south and east of the Capital Region. Behind this storm, dry and cold weather will continue for the remainder of the week. && .HYDROLOGY... No hydrologic issues are anticipated through the week. Dry weather is expected today with a mostly sunny. Dry weather will continue through the remainder of the week for areas north and west of the Capital Region. Meanwhile, southern and eastern areas will see some snow between late tonight and Wednesday night, with the heaviest amounts across Dutchess, Litchfield and Berkshires counties. Total liquid equivalent in these areas will approach up to an inch. Dry weather is then expected behind this storm for the remainder of the week. This snowfall won`t have any immediate impact on area rivers and streams. A slow diurnal snowmelt is expected over the next several days, with temperatures above freezing during the day, and below freezing at night. There will be little impact on the waterways with minimal, if any, rises. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...Winter Storm Warning from 5 AM Wednesday to 8 AM EDT Thursday for CTZ001-013. NY...Winter Storm Watch from late tonight through Thursday morning for NYZ063-064. Winter Storm Warning from 5 AM Wednesday to 8 AM EDT Thursday for NYZ065-066. MA...Winter Storm Watch from late tonight through Thursday morning for MAZ025. VT...None. && $$ SYNOPSIS...Frugis NEAR TERM...Frugis SHORT TERM...Frugis LONG TERM...IAA AVIATION...IAA FIRE WEATHER...Frugis HYDROLOGY...Frugis is the U.S. government's official web portal to all federal, state and local government web resources and services.