Area Forecast Discussion
Issued by NWS Albany, NY

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000 FXUS61 KALY 250252 AFDALY Area Forecast Discussion National Weather Service Albany NY 1052 PM EDT SUN JUL 24 2016 .SYNOPSIS... Hot temperatures, increasing humidity and chances for showers and thunderstorms return for Monday as a frontal boundary approaches from the west. More dry weather is expected from Tuesday through the middle of the week as high pressure builds back in across the region. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... As of 1045 PM EDT, high and mid level clouds have overspread the region. Intervals of mid and high clouds will occur much of the night over our entire region. Light winds will become light south to southwest toward daybreak. Overnight lows should mainly be in the 60s, perhaps barely below 70 in some valley areas from Albany southward. Some showers/thunderstorms may approach from central NY toward daybreak. Will continue slight chance to low chance pops across the Catskills and mid Hudson Valley region to account for this possibility. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... There are quite a few different possibilities as to the evolution and track of convection that develops in the lower Great Lakes and OH Valley overnight. Various mesoscale models have different solutions, some showing a weakened small cluster of showers and isolated thunderstorms along the advancing dew point boundary around or just after daybreak across the eastern Catskills and mid Hudson Valley. Other guidance shows the small cluster tracking well south of the mid Hudson Valley. Other guidance shows most of all the showers and storms dissipating along the dew point boundary through the night, but new strong convection rapidly developing over eastern NY and Western New England around mid morning Monday. The one constant is the dew point boundary with increasing dew points building in from the west but the mode and coverage of any weakening showers and thunderstorms is very much in question. Boundary layer flow will slowly increase from the west and southwest, which is downslope, and there is very little upper dynamics or upper jet support for convection in our region. So, acknowledging isolated to scattered showers and thunderstorms Monday morning into the western Mohawk Valley, eastern Catskills, mid Hudson Valley and into NW CT. This may be updated once showers and storms can be tracked through tonight. Low temperatures with the increasing cloud cover and increasing dew points in the 60s to near 70...but around 60 northern areas and parts of southern VT. Guidance again not in full agreement on coverage, timing and intensity of convection tomorrow. Upper dynamics, upper jet structure and low level forcing will be relatively weak through the day but rapidly increasing low level moisture will contribute to increasing instability. West to southwest boundary layer flow will be downslope...suggesting scattered coverage, not necessarily likely. The amount of mixed mid and high clouds will determine high temperatures but as long as new convection initiates more in the afternoon, intervals of breaks and thinning of mid and high clouds should still allow for highs well into the 80s to lower 90s. Heat indices may approach 100 in the mid Hudson Valley and NW CT but not quite. So, will include in HWO, highlighting the chance that a Heat Advisory may need to be issued later. The instability, CAPES may be solidly over 1000 j/kg in many areas Monday afternoon, along with some hints at some degree of steepening of midlevel lapse rates, suggests that even with the scattered nature of the storms tomorrow afternoon, some could become severe. Our region is in a marginal to slight risk in the severe weather outlook from SPC, with damaging winds the primary threat but some hail could occur as well. The better low level forcing along the advancing low level thermal and moisture boundary and westerly wind shift looks to be during the evening and overnight Monday night when some diurnal cooling should be occurring but keeping potential severe in the forecast through Monday evening. Some low level drying and partial clearing could occur before daybreak with lows in the 60s. Continued drying Tuesday with considerable sunshine and breezy west to northwest winds. Highs Tuesday in the 80s to near 90. Similar weather Wednesday but less wind with highs again in the 80s to around 90. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... This will be a stagnant period of little atmospheric motion to get things moving. As such...our region will be more or less stuck between two frontal boundaries north and south. Waves will ripple along these boundaries...and showers and thunderstorm will be possible each day...particularly approaching and during the weekend. After high temperatures from around 80 degrees in the mountains to the lower 90s down the Hudson Valley on Thursday...showers and an overall increase in cloud cover will keep daily highs in the around 70 lower or mid 80s range for the balance of the period. Overnight lows will be in the upper 50s to upper 60s range for the entire period. Daytime highs at Albany are in the lower 80s...with overnight lows in the lower 60s. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... A warm front will approach from the southwest Monday morning, and lift northeast of the region by midday. A cold front will then approach from the west late Monday afternoon and evening. For most of the overnight hours, mid level clouds will increase. Some showers/thunderstorms currently across central PA may approach KPOU toward daybreak. Otherwise, mainly VFR conditions are expected through daybreak. As the warm front moves across Monday morning, isolated to scattered showers/thunderstorms will be possible at the TAF sites. Have included a VCSH mention at this time to account for this. Additional isolated to scattered showers/thunderstorms may develop along and ahead of the cold front later Monday afternoon. Will include a PROB30 group for this possibility. Outside of any showers/thunderstorms, mainly VFR conditions are expected. Localized MVFR/IFR conditions will be possible within any showers/thunderstorms. Winds will become light/variable overnight, then shift into the south to southwest Monday morning at 5-10 KT. By Monday afternoon, southwest winds may increase and become gusty at times, perhaps up to 20-25 KT in some areas. Winds will be much stronger, and variable in direction in and near any thunderstorms. Outlook... Monday Night: Moderate Operational Impact. Scattered SHRA...TSRA. Tuesday: No Operational Impact. NO SIG WX. Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: No Operational Impact. NO SIG WX. Wednesday Night: No Operational Impact. NO SIG WX. Thursday: Moderate Operational Impact. Slight Chance of SHRA...TSRA. Thursday Night: Moderate Operational Impact. Chance of SHRA...TSRA. Friday: Moderate Operational Impact. Chance of SHRA...TSRA. && .FIRE WEATHER... Hot temperatures, increasing humidity and chances for showers and thunderstorms return for Monday as a frontal boundary approaches from the west. More dry weather is expected from Tuesday through the middle of the week as high pressure builds back in across the region. Relative humidity values will range between 75 and 100 percent tonight and Monday night. Relative humidity values will drop to around 50 to 65 Monday afternoon and to around 40 to 55 percent Tuesday afternoon. Scattered thunderstorms are expected Monday and Monday night. Winds will becoming variable around 5 kt or less tonight. Winds on Monday will become southwest at 15 mph or less. Winds shift to west and northwest at 15 mph or less Monday night, then increase to around 15 mph with possible gusts to 25 mph Tuesday. && .HYDROLOGY... Dry weather will occur through tonight. However, the next frontal boundary will approach for Monday bringing additional chances for showers and thunderstorms. Locally heavy rainfall will be possible with any persistent storms but basin wide amounts should be a half inch or less. Dry conditions return for Tuesday and Wednesday as high pressure builds back into the region. Flows continue to be well below normal for mid to late July at many locations in the Hydro Service Area, especially our western New England counties. 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...NAS NEAR TERM...KL/NAS SHORT TERM...NAS LONG TERM...ELH AVIATION...KL/BGM FIRE WEATHER...NAS HYDROLOGY...NAS is the U.S. government's official web portal to all federal, state and local government web resources and services.