Area Forecast Discussion
Issued by NWS Albany, NY

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433 FXUS61 KALY 290849 AFDALY Area Forecast Discussion National Weather Service Albany NY 449 AM EDT Wed Mar 29 2017 .SYNOPSIS... Morning clouds will give way to increasing breaks of sunshine today with temperatures close to normal. After a dry and seasonable day on Thursday, another storm system will impact the region for Thursday night through Friday night with rain and snow. Although valley areas will only see limited accumulations due to mixing with rain, higher terrain areas may see at least a moderate accumulation of snow. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... As of 449 AM EDT...A wave of low pressure along a frontal boundary continues to depart to the south of New England. All of the higher and colder cloud tops associated with this feature are now well east of the region, however, plenty of lingering low-level moisture continues to allow for a lot of low stratus clouds this morning. After the morning will begin cloudy, daytime heating will combine with cooling temps aloft to promote mixing, and help dissipate these clouds. As an upper level trough slides by to the north of the region, 850 hpa temps will fall from around 0 to -5 degrees C this morning to -4 to -9 degrees C by this evening. Despite this nearby upper level feature, no precip is expected and it should be dry through the entire day. Good mixing will still promote for seasonable temps, with valley highs in the mid 40s to mid 50s. Higher terrain areas will be cooler with temps only in the upper 30s to low 40s. The good mixing will allow for some gusty winds, especially by this afternoon. Northwest winds may gust 20-30 MPH at times, especially in channeled valleys and across the higher elevations. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... As high pressure passes over the region, dry and quiet weather is expected for tonight into tomorrow. Skies will generally be fairly clear, although some clouds are expected by late in the day tomorrow as the next storm system starts to approach. Winds will diminish tonight and be lighter for Thursday. Temps will be in the 20s tonight and mainly be in the 40s on Thursday. The next storm system will be approaching for Thursday night. A closed off low at 500 hpa will be sliding across the Ohio Valley on Thursday night into Friday and towards the mid-Atlantic for Friday night. At the same time, another weak northern stream feature will be approaching out of southern Canada, although model guidance suggest that these two features don`t fully phase at they head towards the eastern United States. At the surface, the initial low will track through the Ohio Valley on Friday, while another low develops east of the mountains and rapidly develops for Friday night as it heads east towards the western Atlantic Ocean. The main driver for our weather will be the potent southern stream system, which will have ample moisture out of the Gulf of Mexico and western Atlantic. As this storm approaches, precipitation looks to break out from west to east on Thursday night thanks to isentropic lift/warm air advection. With temps both at the surface and in the boundary layer initially being cold (along with wet-bulbing processes), precip looks to start out as a period of snow for Thursday night into early Friday morning. This will occur for both valley and high terrain areas, with a light accumulation possible by the morning commute (especially for areas west of the Hudson Valley). Lows will generally be in the 20s to near 30 on Thursday night as precip begins. The high pressure that provided the cold air mass to start will be departing off the coast of New England on Friday morning. As a result, through the morning hours, a persistent (although light) east-southeast flow at low to mid levels, along with the strong late March sunshine, will aid in warming the boundary layer. It will be a battle between this warming and the cooling of falling wintry precip for what p-type occurs. Ultimately, model guidance suggest that valley areas looks to transition over to rain or a rain/snow mix by afternoon, while higher terrain areas remain mainly snow. At the same time, warming aloft (around 800 hpa) could also allow for some sleet at times, mainly for areas south of Interstate 90. Temps in valley areas look to reach the mid 30s, with low 30s for the higher terrain areas by Friday afternoon and these temps look to hold steady at these values for Friday night. This will all be a close call, as heavy precip could allow the column to go isothermal at times, with precip falling as heavy, wet snow, even in valley areas. Models and ensembles do suggest plenty of QPF, with many showing over 1.00" liquid having fallen by Friday night. For now, we have a few inches of snow accumulation (4" or less) for valley areas, with accumulations of 6"+ for the mountains, with the highest amounts across the southern Green Mountains and the southern Adirondacks. This will be subject to change and is a rather low confidence forecast at this time. Snow ratios will be fairly poor through the event, as the best dendritic growth zone will be around 500-600 hpa, which is above most of the strong lift. Also, boundary layer temps at or just above freezing will aid in some melting, making the snow wet and dense. && .LONG TERM /SATURDAY THROUGH TUESDAY/... There are chances for lingering precipitation Saturday morning as the system departs. Precipitation may linger into the afternoon in southern VT. Highs Saturday in the 40s with around 40 higher terrain. High pressure and dry weather is expected to build into the region Sunday and exit to the east on Monday. Highs Sunday in the mid 40s to around 50 but around 40 higher terrain. Highs Monday, with warm advection increasing, in the lower to mid 50s but mid 40s higher terrain. Another upper cut off system is expected to eject out of the southern plains toward the northeastern U.S. Monday night through Tuesday. There are some disagreements in sources of guidance as to how much low level cold air is anchored in our region from the high pressure off southern Canada. The upper cut off system is not as strong and deep as would be needed for widespread snow and there are indications it may track too far south for lots of precipitation this far north. Boundary layer temperatures are indicated to be around or just above freezing. So, we have to wait until next weekend to see what potential precipitation types and transitions we can expect with the Monday night through Tuesday system. Until those details become clearer, indicating chances for rain and snow later Monday night transitioning to rain Tuesday. Highs Tuesday in the 40s. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... A cold front continues to exit but high pressure is slow to build into the region. Low level moisture is lingering as well as cloud cover. There are gradual trends of rising ceilings and improving visibilities from north and west to south and east. However, there are areas of drizzle near KALB that may cause some intermittent lower ceilings and visibilities through about 11Z. The drizzle could spread to KPSF and KPOU through 12Z-13Z as well and have indicated intervals there. Predominant visibilities at all TAF sites should be VFR, except if there are intervals of drizzle. Ceilings are MVFR but there could be intervals of IFR ceilings again if drizzle occurs. the areas of drizzle look to be south of KGFL on radar and trending south, so keeping drizzle out of KGFL. After 12Z-13Z, any chances for drizzle should end. Ceilings should rise to VFR by 16Z-18Z and remain VFR through 06Z tonight. Visibilities are expected to remain VFR as well. Winds are expected to remain north at less than 10 Kt through daybreak. North to northwest winds will increase to 10 to 20 Kt with gusts over 20 Kt later this morning through afternoon. The north to northwest winds will diminish to less than 10 Kt this evening. Outlook... Thursday: No Operational Impact. No Sig Wx. Thursday Night: Moderate Operational Impact. Likely SN. Friday: High Operational Impact. Definite RA...SN. Friday Night: High Operational Impact. Definite RA...SN. Saturday: Moderate Operational Impact. Scattered SHRA...SHSN. Saturday Night: No Operational Impact. NO SIG WX. Sunday: No Operational Impact. NO SIG WX. && .FIRE WEATHER... Much of eastern New York and western New England continues to have snow on the ground. Although snow melt has been ongoing recently and most valley areas only have snow depth of a few inches, much deeper snowpack remains across the hills and mountains. Clouds will break some sunshine today with near seasonable temperatures. Although northwest winds will gust 20-30 mph this afternoon, RH values will remain elevated (generally above 45-55 percent). After a dry day Thursday, more precipitation in the form of rain and snow is expected on Friday. && .HYDROLOGY... The recent rainfall and snowmelt has led to some rises on rivers and streams. A few river points came close or reached action stage, but no flooding occurred. With daytime temperatures well above freezing, some additional snowmelt is expected today and tomorrow, but no precipitation is expected. This should allow rivers and streams to slowly start to recede by later today or tomorrow. Another storm system is expected on Thursday night through Friday night. Precipitation will be in the form of rain and snow, with mainly snow or mixed precipitation across the highest elevations. This wintry precipitation will initially prevent much runoff from occurring. Still, some rivers are expected by Friday into Saturday. At this point, the MMEFS would suggest no flooding is expected, although this will ultimately depend on precipitation type and exact amounts which are still uncertain. 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...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...Frugis NEAR TERM...Frugis SHORT TERM...Frugis LONG TERM...NAS AVIATION...NAS 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.