Area Forecast Discussion
Issued by NWS Albany, NY

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964 FXUS61 KALY 261057 AFDALY Area Forecast Discussion National Weather Service Albany NY 657 AM EDT Wed Jul 26 2017 .SYNOPSIS... High pressure will briefly build into the region today with improving conditions. However, an approaching frontal system will bring some showers and thunderstorms for Thursday, but clearing conditions are expected for the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... As of 625 AM EDT...Patchy dense fog across the region as an SPS was issued to highlight this hazard. Enhanced experimental GOES 16 satellite data continues to clearly depict fog lining up along the rivers and deeper valleys. With sunrise, conditions should improve rather quickly this morning. Otherwise, low and mid level clouds were evident along the I81 corridor as we will keep a partly sunny to mostly sunny forecasts at this time. Prev Disc...Impressive experimental GOES 16 nighttime microphysics advanced channels revealing the westward advecting stratus deck and within an hour of its passage, lower level stratus and fog formation, especially in the valley and near bodies of water. So clouds west of the Hudson and a mainly clear start to the east with patchy dense fog. All short term NCEP Model suite guidance and global models suggest along the I81 corridor an enhanced region of low level moisture (H850 and below). As the surface high slides east of the region, this moisture does return back to the region but too what extent is not too clear. Given the advective nature and July sunshine, we will opt for a partly sunny forecast. Clouds may be a bit more across the higher terrain with daytime heating as high temperatures should easily be about 10 degrees warmer with mainly 70s with around 70F for the higher terrain. Clouds seen upstream from the convection through the upper Mississippi River Valley through the upper Great Lakes will advect into the northern portions of the region later this afternoon. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... The aforementioned clouds upstream will advect in across the remainder of the region tonight as frontal boundary drifts southeastward. Timing is rather similar with the frontal placement in the vicinity of the St Lawrence Valley around or shortly after midnight. This will enhance the chances for showers across the Dacks, Lake George Saratoga Region and southern VT. As the mid level westerlies increase, this too advects in additional mid level instability where Showalter values drop toward 0C by 12Z Thursday as we will continue with the slight chance for thunderstorms. Overnight lows will be a bit milder than recently with mainly 60s expected as dewpoints climb toward 60F. Per the latest coordination messages and outlooks from SPC, all of our region is within a `marginal risk` for severe thunderstorms on Thursday. While modest shear will be in place of 25-35kts, main question will be the degree of insolation and resultant instability. Modified parcels point toward SBCAPES over 1000 J/KG yet lapse rates were near or just below 6 C/Km. Given a slow dropping wet bulb zero heights and relative speed shear, we will enhance the thunderstorm wording to include gusty winds and small hail. Highs Thursday could climb toward 80F for valley locations with otherwise 70s elsewhere. Thursday night there is a growing consensus that this frontal zone will track rather quickly from northwest to southeast through the evening hours. This would suggest holding onto some PoPs/Wx for southern zones earlier on then drying conditions for the remainder of the overnight period as surface ridge builds in from central Canada. So clearing skies from north to south through the night as overnight lows from the 50s from the Dacks to 60s for valley locations. && .LONG TERM /FRIDAY THROUGH TUESDAY/... The upper pattern becomes complex through the weekend with an increasing consensus that an upper low develops south of our region Friday and tracks along or just south of Long Island late Friday into Saturday. Most sources of guidance and ensembles keep the deeper moisture and most of the extensive cloud cover just south of our forecast area. However, the northern extent of clouds and isolated showers could get into the mid Hudson Valley and NW CT Friday and Friday night before high pressure builds into our region from Canada and the Great Lakes late Saturday. Highs Friday and Saturday in the mid to upper 70s but cooler in higher terrain. Mean upper troughing remains just east of our region Sunday and Monday with some upper ridging building east from the Great Lakes north of the exiting upper troughing. The upper ridging will aid in some slow gradual warm advection. So, dry weather and more sun than clouds Sunday and Monday as long as upper troughing does exit just to the east as guidance suggests. Highs Sunday in the upper 70s to around 80 but lower 70s higher terrain. Highs Monday in the lower to mid 80s but mid to upper 70s higher terrain. By Tuesday-Wednesday there is a loose consensus for the next weak cold front to drop south out of Canada with little moisture and weak low level forcing. So, intervals of clouds and sun with isolated to scattered showers and thunderstorms may be possible. Highs Tuesday and Wednesday in the lower to mid 80s but mid to upper 70s higher terrain. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... Patchy dense fog is currently impacting the area this morning with LIFR conditions at all TAF sites except POU. This fog should lift/burn off by around 13Z this morning. VFR conditions should then prevail through the rest of the forecast period. Some showers may be possible at the tail end of the period as the next cold front approaches from the north and west. Outlook... Thursday Night: Low Operational Impact. Slight Chance of SHRA. Friday: Low Operational Impact. Slight Chance of SHRA. Friday Night: Low Operational Impact. Slight Chance of SHRA. Saturday: No Operational Impact. NO SIG WX. Saturday Night: No Operational Impact. NO SIG WX. Sunday: No Operational Impact. NO SIG WX. Sunday Night: No Operational Impact. NO SIG WX. Monday: No Operational Impact. NO SIG WX. && .FIRE WEATHER... No fire weather related issues expected, as our area saw a wetting rain recently. RH values will fall to 40 to 70 percent on Wednesday with very light winds. The next chance for rain showers and thunderstorms will be on Thursday. && .HYDROLOGY... Mainly dry weather is expected through today with breaks of sunshine. The next frontal system will return the chance for some showers and thunderstorms on Thursday into Thursday evening. Model guidance is starting to come together that it should be through by Friday morning, so dry weather looks to return for Friday into the weekend. Rainfall amounts will be variable on Thursday due to the track of showers/thunderstorms, but widespread heavy rainfall is not expected. Aside from a brief burst of heavy rainfall from a thunderstorm, no flooding issues are anticipated with this rainfall. 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...BGM NEAR TERM...BGM SHORT TERM...BGM LONG TERM...NAS/JVM AVIATION...JVM FIRE WEATHER...Frugis/BGM HYDROLOGY...Frugis/BGM

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