Area Forecast Discussion
Issued by NWS Albany, NY

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000 FXUS61 KALY 231943 AFDALY Area Forecast Discussion National Weather Service Albany NY 343 PM EDT Wed Aug 23 2017 .SYNOPSIS... Mainly dry and comfortable weather is expected for the rest of the week and into the weekend with temperatures generally a little below normal levels for late August. && .NEAR TERM /THROUGH TONIGHT/... Afternoon water vapor imagery shows deep occluded cyclone over central Quebec. The system`s cold front, along with shower and thunderstorm activity, has pushed well offshore. Plentiful dry air has streamed into the Northeastern US in the wake of yesterday`s front, with PWAT values falling from 1.80 inches on last night`s 00Z KALY sounding to 0.95 inches on this morning`s 12Z sounding. The lower humidity has been noticeable here at the surface, with dewpoints falling into the lower and middle 50s across the CWA under scattered cumulus and a few cirrus. Looking upstream, there exists a secondary front/wind shift boundary upon which a line of showers has tracked to the northeastern shore of Lake Ontario. High resolution models do not seem to be picking up on this activity well. Have expanded PoPs slightly into the Western Adirondacks between roughly 21Z and 02Z as extrapolation of this line brings it across northern portions of Herkimer/Hamilton Counties. Otherwise, a tranquil evening and night is expected. Low temperatures tonight will be much lower than recent nights in the mid-40s to mid-50s. Some shallow fog is possible in favored river valleys, but due to the overall dryness of the airmass, as well as some question with respect to decoupling potential tonight as a modest pressure gradient remains over the area, have not included fog in the public forecast. && .SHORT TERM /THURSDAY THROUGH SATURDAY/... For the remainder of the week into Saturday, models are in good agreement that a mean longwave trough will be in place over the Northeastern US, with a mean longwave ridge over the Northern Plains. At the surface, this will promote an expansive region of high pressure from Hudson Bay into the Mid-Mississippi Valley and expanding into the Northeastern US. H500/T850 anomalies will average 1-2 standard deviations below normal during this period, so temperatures can be expected to come up on the order of 5F below normal. With a dry airmass in place (PWAT values AOB 0.75"), precipitation chances will be low throughout the period. However, a shortwave trough now evident over the southern Canadian Prairies will rotate into the Northeastern US late Thursday/Thursday night, going from positive to neutral tilt. Lift from this wave, along with diurnal/terrain effects, may generate a few isolated showers over the Southern Adirondacks/Mohawk Valley/Southern Greens. As high pressure exerts more of an influence Friday and Saturday, have a dry forecast everywhere. Friday night looks to be the coldest night of the period, with temps bottoming out mainly in the 40s to around 50. Can`t rule out some 30s in high-elevation valleys. Last time the temp fell into the 40s at KALB was June 8. && .LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/... A very tranquil period is expected Saturday night through Wednesday. The mean upper trough axis is nearby through about Monday, then flat upper ridging builds into our region Tuesday and Wednesday. Surface high pressure will build out of Canada and the Great Lakes into our region through the weekend and beginning of the week before the flat upper ridging and surface high pressure builds east into our region toward the middle of the week, allowing for some southerly low level flow and slow and gradual warm advection. This stable upper and surface pattern will result in high temperatures nearly the same each day from Sunday through Wednesday with just slow warming through the period. Highs are expected to be in the mid 70s trending to upper 70s through the period in most areas but mid 60s trending to lower 70s in higher terrain. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... The region will remain under cool, cyclonic flow as the upper level low moves northeastward across eastern Canada today. VFR conditions are therefore expected through the TAF period with mainly scattered mid and upper level clouds. Some radiational fog is possible at KGFL and KPSF late tonight with mostly clear skies as winds become calm. Westerly winds around 5 to 15 knots will remain gusty (up to 20 to 25 knots) through the afternoon but will then dampen to around 5 knots or less for the remainder of the TAF period as surface high pressure builds into the region. Outlook... Thursday Night through Monday: No Operational Impact. NO SIG WX. && .FIRE WEATHER... Seasonably cool airmass in place for the remainder of the week into the weekend, with high temperatures averaging in the mid- 60s to mid-70s. After areas of morning dew/shallow fog, RH values will bottom out in the 45 to 55 percent range Thursday and Friday. Winds Thursday and Friday will be somewhat lighter than Wednesday, generally out of the northwest at 5 to 10 mph. A few isolated showers are possible over the higher terrain Thursday and Thursday night, otherwise dry. && .HYDROLOGY... No hydrologic issues are anticipated over the next five days. Showers and thunderstorms on Tuesday allowed for some very minor rises on rivers and streams, mainly smaller creeks. With dry weather expected to continue, river levels will recede or remain steady. Very little to no precipitation is expected through the weekend, which will allow for river levels to hold steady. 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. && .EQUIPMENT... The KENX radar will likely be down through at least Friday, September 1st for the bull gear replacement. We are waiting for a ROC maintenance team and parts to arrive to assist local technicians with the repairs. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...Thompson NEAR TERM...Thompson SHORT TERM...Thompson LONG TERM...NAS AVIATION...JVM FIRE WEATHER...Thompson HYDROLOGY...Thompson EQUIPMENT...ALY Staff

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