Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/01/17


Area Forecast Discussion
National Weather Service Albany NY
1040 PM EDT Tue Oct 31 2017 .SYNOPSIS... Lake effect rain and snow showers will continue tonight across the western Adirondacks with fair and dry weather elsewhere. Overnight temperatures will be quite chilly, in the upper 20s to lower 30s. More unsettled weather is expected to arrive tomorrow afternoon, as a low pressure system tracks from the upper Great Lakes into northeast Canada dragging a warm front and then a cold front through our region. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... AS OF 1039 PM EDT...The latest KTYX and regional radar mosaic shows a narrow lake effect band in the westerly flow off Lake Ontario has weakened and become more diffuse in the last few hours, as the subsidence inversion lowers and the boundary layer winds continues to veer. The latest 3-km HRRR also supports this weakening trend. A few snow showers or flurries are possible across the western Adirondacks before they diminish. The skies will become partly cloudy to mostly clear for a brief period of time before some high clouds clouds increase from the Ohio Valley. The winds will continue to become light to calm as temps will fall in the chilly air mass into the upper 20s to lower/mid 30s. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/... Clouds and low level moisture will be increasing throughout the day Wednesday as the winds shift towards the southwest ahead of the next low pressure system. This low pressure system is expected to lift through the Great Lakes region and into northeast Canada late Wednesday into Thursday, dragging a warm front through the region. Showers are expected ahead of this warm front beginning Wednesday morning. Temperatures on Wednesday will remain quite chilly, in the low 40s to near 50 degrees under cloudy skies. Shower chances continue overnight Wednesday night as the warm front lifts northward through the region. The best chance for steadier rainfall will be across the Adirondacks, Lake George-Saratoga Region and the Mohawk Valley, closer to the better dynamics tracking north and west of the region through Thursday morning. Temperatures overnight may be tricky depending on the timing of the warm front passage compared to the shower activity, but they are currently forecast in the upper 30s to low 40s. Rain should lift north and east of the region by Thursday afternoon as southwesterly winds increase. Temperatures during the afternoon will feature a return to above normal values, in the upper 50s to mid 60s. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... We begin the long term with a broad and moist southwest flow regime ahead of an approaching cold front through Thursday night. Low level jet magnitudes approaching 50kts are in the forecast per global model consensus which should keep considerable cloud coverage and the threat for periods of wet weather (showers and/or drizzle). The best chance for showers will be closer proximity to the front which is progged to remain north and west of Albany. Cold frontal passage is well timed per global model consensus to occur Friday morning. Then cold advection will pursue in the wake of frontal passage with increase west-northwest winds. Probabilities of precipitation will diminish from northwest to southeast through the day with mainly dry conditions expected through the afternoon hours. Thereafter, 1035mb surface high builds in from just north of the Great Lakes into the northeast corridor through most of Saturday. Then confidence goes lower Saturday night as the ECMWF remains the most aggressive with a surge of warm advection and isentropic lift for periods of light precipitation Saturday night. The GFS and GGEM are in closer agreement with a more gradual increase in broad warm advection as we will hold off on too much influence from the ECMWF at this time. Regardless, seems clouds will be on the increase again through the weekend with an increase in wet weather conditions starting mainly Saturday night into the day on Sunday. Another cold front approaches Monday where the chance for showers, perhaps a rumble of thunder as Showalters drop to near 0C, will be on the increase. Global models are in somewhat good agreement with this scenario as we will keep PoPs a bit higher than climatology. Temperatures through the period will average near to a bit above normal with precipitation near to above normal. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... High pressure will briefly ridge in over the region tonight. The sfc high will quickly shift east of New England in the morning, as a mid level disturbance and a warm front approach from the Ohio Valley and Mid Atlantic States with a chance of some showers late in the afternoon thru the overnight period. Expecting mainly VFR conditions for KGFL/KALB/KPSF/KPOU prior to 19Z/TUE. The clouds will decrease early this evening except at KGFL where some stratocumulus due to the lake effect fetch may linger until 04Z-08Z. Some thin high clouds will increase after 06Z for all the terminals. The clouds will gradually thicken and lower from the south/southwest to the north/northeast across the region with bases in the 10-15 kft AGL range by 13Z-15Z/TUE. The clouds will continue to thicken and lower by the afternoon with low to mid level warm advection in advance of the warm front. There is a chance of light rain showers in the afternoon especially after 19Z-21Z and PROB30 groups were used at all the TAF sites. We did place some high MVFR cigs/vsbys at KPSF in the PROB30s, but kept all other sites VFR at this time with bases in the 3.5-5 kft AGL range prior to 00Z/WED. The west to southwest winds of 4-7 kts winds will become light and variable at 3 kts or less/calm prior to midnight. The winds will be from the south to southeast at less than 10 kts in the late morning thru the afternoon. Outlook... Wednesday Night: Moderate Operational Impact. Scattered SHRA. Thursday: Moderate Operational Impact. Scattered SHRA. Thursday Night: Moderate Operational Impact. Chance of SHRA. Friday: Moderate Operational Impact. Chance of SHRA. Friday Night: No Operational Impact. NO SIG WX. Saturday: No Operational Impact. NO SIG WX. Saturday Night: Moderate Operational Impact. Chance of RA. Sunday: Moderate Operational Impact. Chance of RA. && .FIRE WEATHER... Scattered rain and snow showers will continue across the western Adirondacks through Tuesday night with a cooler and more seasonably airmass in place. Overnight temperatures will be quite chilly, in the low 30s. More unsettled weather is expected to arrive Wednesday afternoon as a low pressure system tracks from the upper Great Lakes into northeast Canada dragging a warm front and then a cold front through our region. && .HYDROLOGY... Most of the rivers, creeks and streams were receding after receiving substantial rainfall Sunday and Sunday night. Mainly dry conditions are expected tonight except across the western Adirondacks where some lake effect snow and rain showers are expected. More unsettled weather is expected to return Wednesday afternoon into Thursday night. Rainfall amounts at this time appear to range from a tenth of an inch southeast to three quarters of an inch northwest. 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...11/Wasula NEAR TERM...Wasula SHORT TERM...11/JVM LONG TERM...BGM AVIATION...Wasula FIRE WEATHER...11/JVM HYDROLOGY...11/JVM
Area Forecast Discussion
National Weather Service Gaylord MI
1053 PM EDT Tue Oct 31 2017 .UPDATE... Issued at 1044 PM EDT Tue Oct 31 2017 WSW Lake effect now ongoing as expected across northern Emmet County, northwest Cheboygan and southern portions of Mackinac and Chippewa Counties. The most intense activity is across northwest Emmet County where several inches of accumulation are expected by early morning...hence the winter weather advisory. One worry is with winds continuing to slowly back into the south southwest...a smaller portion of the advisory area will be affected. Will leave headline as is...since the snow will be of the very greasy variety and it`s the first "event" of the season. Besides the lake effect, nothing of note going on across the remainder of the forecast area. && .NEAR TERM...(Tonight through Wednesday) Issued at 411 PM EDT Tue Oct 31 2017 ...Lake effect snow to reinvigorate over the tip of the mitt... High impact weather potential...potentially healthy snowfall amounts tonight in northern Emmet Co and surroundings. High pressure will rapidly transit the Ohio Valley this evening. Our low-winds will back considerably in response, becoming sw by late evening and south for Wednesday. Diurnal heating has done its usual thing to lake effect, with reasonably broad coverage of cellular convection. This is still snow in interior sections, mixy in spots toward Lakes MI/Huron. Precip trends are the main concern. As we head toward dusk, diurnal instability wanes. Showers outside of lake effect regimes will fade out, while within them showers will attempt to reorganize into bands. With sw flow arriving, the prime area of concern will be centered on the tip of northern lower MI. Our air remains plenty cold enough for lake effect, and for snow at that. We won`t dislodge the cold air until late in the day on Wednesday. In the meantime, we have a fairly lengthy period of stable sw flow from 03z to 09z tonight. Hi-rez short-term guidance really latches onto this event. Both HRRR and Rap runs crank out near or over half an inch of liquid QPF in parts of northern Emmet Co tonight. (A recent HRRR run - not the most current - had a 0.85" bullseye). One difference from last night is that we are targeting an area outside of the high elevations. The BL should be warmer, and snow-liquid ratios lower. That`s also the end of a very long fetch over a warm Lake MI - how warm will the marine layer be? That said, temps in that area are still bottoming out when precip is occurring (Mackinac Isl crashed to 35f during a recent snow shower). And PLN at 39/31 presently would support wet snow via wet bulb effects. Am going to post a one-county winter wx advis tonight for Emmet, with 2-6 inches of potential snowfall north of Harbor Spgs. Snowfall totals of around 3 inches will lead into the St Ignace area, far nw Cheboygan Co, and small parts of eastern Chip/Mack Cos. The impacted areas and snowfall amounts are not large enough to warrant adding those counties to this advisory. For Wednesday, continued backing of the low-level flow will push snow showers off of Lake MI further west, into central and western Mack Co and eventually out to ISQ. A decrease in intensity is expected (especially in the afternoon), as continued warm advection erodes and shallows-out instability. This will also introduce more of a rain-snow mix into leftover precip. Will keep snowfall amounts less than an inch in upper MI. Otherwise, spotty rain/snow showers will also impact the nw lower MI coastline, especially in the morning. Better synoptic forcing and more widespread precip with the next system looks to arrive just after 00z. Min temps tonight in the 20s to around 30f. Max temps Wednesday near 40f to the mid 40s. && .SHORT TERM...(Wednesday night through Friday) Issued at 411 PM EDT Tue Oct 31 2017 ...Widespread precipitation Wednesday night... High Impact Weather Potential...Minor slushy snow accumulations possible Wednesday evening across interior northern Lower and eastern Upper. Pattern Synopsis/Forecast...A potent shortwave and developing surface low will track through the Upper Midwest and then cut across northern Lake Superior Wednesday night into Thursday. Vigorous warm air advection will develop Wednesday evening and continue overnight as a ~50 knot low level jet passes just southeast of the forecast area. This will pump increasing moisture into the region with PWATs climbing above 0.7" for much of northern Lower overnight. Together these features and the increased moisture will produce widespread precipitation overnight across northern Michigan as they cross the region. A cooler, drier airmass will progressively filter back into the area on Thursday as the system departs and a large Canadian surface high pressure builds in behind it. Primary Forecast Concerns...Precip chances and precip-type evolution Wednesday night into Thursday. Any lingering lake effect showers over western Chip/Mack counties should come to a fairly quick end Wednesday evening as warm air advection ramps up and increasing low level flow backs to the SSE. Bulk of the more widespread precip looks to overspread northern Michigan after 8pm Wednesday and eventually exit our eastern counties towards daybreak Thursday. At time of onset, forecast soundings across northern Michigan are largely sub-freezing except for an initially dry surface layer. Wet bulb zero heights are quite low to start across eastern Upper and interior northern Lower, so think precip will begin as snow or a rain/snow mix in these areas. Near the coasts, precip should largely stay just rain. As WAA intensifies from south to north overnight (leading to a nocturnal temperature rise after midnight), soundings gradually warm and low levels become almost isothermal. This will result in a south-to- north transition to just rain, but until then it looks like it may snow enough to produce a slushy inch or so of accumulation over interior northern Lower, perhaps slightly higher amounts across interior eastern Upper. The LLJ and strongest WAA will lift off to the northeast around or shortly after daybreak Thursday, taking the bulk of the heaviest precip with them. However, scattered light rain showers will be possible during the day as some mid-level energy and a somewhat diffuse cold front work through the area. Additionally, it looks to get cold enough aloft to generate enough lake instability over Lake Superior to introduce lake effect rain showers over eastern Upper late Thursday afternoon/evening. Influx of drier air as high pressure noses into the area Thursday night will eventually bring an end to all remaining precip overnight and allow for a cool but dry day with some sunshine. .LONG TERM...(Friday night through Tuesday) Issued at 411 PM EDT Tue Oct 31 2017 High Impact Weather Potential...Minimal. Unsettled weather returns as we head into the weekend with the large surface high departing. Widespread warm air advection aloft out ahead of a developing low east of the northern Rockies will kick off a band of precip over the Upper Great Lakes late Friday night into Saturday. As the parent low ejects towards Hudson Bay early next week, a trailing cold front will eventually cross northern Michigan. So, looking like more wet weather at times through the weekend and cold enough nighttime temperatures to support some nocturnal snow showers, mainly inland. Another incoming surface high looks to dry things out a bit for most Monday into Tuesday, but a cold airmass aloft may support additional lake effect showers off Lake Superior. Temperatures will briefly warm a bit Sunday into Monday with daytime highs in the 50s for much of northern Lower. Cooling back down by Tuesday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 752 PM EDT Tue Oct 31 2017 Lake effect showers gradually getting shunted towards the Straits this evening as winds shift SW. PLN will be most impacted of all the terminals overnight as a band of lake effect snow is expected to develop in its vicinity. Looking like SW flow will carry the band over PLN through around 06Z, before winds subtly become more southerly and likely shunt the band farther north through daybreak. Temporary MVFR vsby and cigs possible with the heavier snow showers. MBL and TVC will likely see some transient snow shower activity overnight and should generally remain VFR. Should be dry on Wednesday with somewhat breezy southerly winds in the afternoon. && .MARINE... Issued at 411 PM EDT Tue Oct 31 2017 Ongoing small craft advisories are winding down in some waters, though will reassess shortly as to whether any extensions are in order. Advisory-level conditions are expected to return to at least Lake MI by Wed afternoon, as high pressure moves east and stronger southerly winds returns. && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY until 8 AM EDT Wednesday for MIZ016. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...AS NEAR TERM...JZ SHORT TERM...MK LONG TERM...MK AVIATION...MK MARINE...JZ
Area Forecast Discussion
National Weather Service Spokane WA
849 PM PDT Tue Oct 31 2017 .SYNOPSIS... Clear skies tonight will allow temperatures to fall into the 20s early Tuesday morning. A much cooler, wet and unsettled weather pattern will develop Wednesday night and will continue through the weekend bringing heavy snow to the mountains and the northern valleys Wednesday night through Saturday. && .DISCUSSION... After a dialog with neighboring forecast offices concerning the 18Z nested NAM model and some of the HRRR runs depiction of potentially intense snowfall band oriented along the cold front dropping down through Montana and pushing into parts of North Idaho it was decided a winter weather advisory advertising a localized potential of 1-3 inches of snow for Idaho zones 1 and 4 should be tacked onto the winter storm watch for the storm system moving through Wednesday night through Friday morning. /Pelatti && .AVIATION... 00Z TAFS: Northwest to southeast oriented jet stream sags over the aviation site tonight and lingers overhead through a good portion of tomorrow. The strong northwest winds aloft brought about by this jet stream positioning may cause low level wind shear issues at times during the overnight and morning hours. During the afternoon and evening hours the winds should mix down a reasonable amount to decrease the low level wind shear. Otherwise some light rain showers over the TAF sites tomorrow during the day starting as early as 12Z Wednesday but more likely after 15Z Wednesday may bring MVFR ceilings on into tomorrow afternoon. /Pelatti && .PRELIMINARY POINT TEMPS/POPS... Spokane 35 49 35 42 34 36 / 10 20 70 90 100 90 Coeur d`Alene 34 47 34 40 33 35 / 10 30 70 100 100 100 Pullman 39 50 36 46 38 42 / 0 40 50 50 90 100 Lewiston 42 57 40 51 41 46 / 0 40 50 30 70 90 Colville 32 51 32 35 26 35 / 20 20 60 100 100 100 Sandpoint 31 46 31 33 28 32 / 20 80 80 100 100 100 Kellogg 34 43 33 39 33 34 / 20 80 90 100 100 100 Moses Lake 34 57 33 50 37 45 / 0 20 20 30 50 50 Wenatchee 39 55 36 48 35 40 / 0 10 20 60 70 50 Omak 34 54 33 37 31 36 / 10 20 20 90 100 60 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Winter Weather Advisory from 8 AM to 1 PM PDT Wednesday for Central Panhandle Mountains-Northern Panhandle. Winter Storm Watch from late Wednesday night through Friday morning for Northern Panhandle. WA...Winter Storm Watch from late Wednesday night through Friday morning for Northeast Mountains-Okanogan Highlands. && $$
Area Forecast Discussion
National Weather Service Shreveport LA
913 PM CDT Tue Oct 31 2017 .UPDATE... Light to moderate rainfall has pushed eastward from central TX to across eastern TX and into deep east TX and northern LA late this evening. Intermittent lightning was noted just west of the county warning area though it can not be ruled out. There is a wane in precipitation across southeast OK and extreme northeast TX and southwest AR late this evening, however near term high- resolution computer models such as the HRRR suggest additional precipitation will develop and fill in overnight. Due to recent radar and expected trends, have gone ahead and increased POPs to the definite category /where areas are experiencing rainfall/ and dropped POPs off a bit to slight chance/low end chance category with lack of rainfall /before 06Z/. After midnight, rain should be area-wide if the HRRR is indeed correct, which seems to be valid given continual development of showers upstream across central TX. Otherwise, tweaked the surface temperatures as it was cooling off a bit faster than expected, but should start to level off due to the extensive cloud cover. Subsequently tweaked the dewpoint temperatures and relative humidity values. Have a safe and fun Halloween! && .PREV DISCUSSION... /issued 737 PM CDT Tue Oct 31 2017/ AVIATION... For the 01/00Z TAF period, a mix of low VFR/MVFR cigs to begin the period and they will further deteriorate through this evening and overnight hours as rain showers increase in coverage and intensity. Vsbys will also drop in heavier showers and with some fog forming as a warm front pushes back northward after midnight. This may also lead to some embedded thunderstorms accompanying the widespread showers through Wednesday morning. Cigs/vsbys will likely not show much improvement until Wednesday afternoon as the showers gradually begin to exit the region. Some sites may be VFR conditions return late in the period, mainly in east Texas where convection will end a bit earlier. Winds will be mostly light and variable overnight with the front lingering south, and then they will trend SE with the returning warm front shifting north with speeds increasing to near 10 kts. /19/ PREV DISCUSSION... /issued 521 PM CDT Tue Oct 31 2017/ DISCUSSION... Patchy lgt rain beginning to increase across area, with larger area of rain and embedded convection slowly movg across I-35 eastward towards the area. Saturation from the top down is occurring so rainfall to begin as lgt and gradually increase. Also, a warm front over se TX into central LA may shift slightly nwd, providing additional focus for enhanced rainfall and provide trigger for tstms as stg low lvl shear and decent mid lvl lapse rates already in place. One to near two inches of rain is possible overnight into early Wed before dry slotting occurs over at least a portion of the area, but leaving in low pops across eastern portions of area thru Thu. Meanwhile, a stg upper lvl ridge building over nrn MEX will create upper level difluence over eastern portions with an overall warming trend as highs climb into the 80s over the wknd. Instability will increase Friday but with more limited moisture and expect discrete but widely scattered tstms later Friday before mid lvls begin to warm and continue to dry out making for a mostly rain free remainder of wknd./07/ && .PRELIMINARY POINT TEMPS/POPS... SHV 50 74 65 82 / 100 70 20 20 MLU 55 73 65 82 / 60 80 30 30 DEQ 44 67 57 80 / 60 30 10 20 TXK 47 66 63 80 / 80 50 10 20 ELD 48 69 63 80 / 100 70 20 30 TYR 51 74 66 83 / 80 40 10 10 GGG 50 74 64 82 / 100 60 10 10 LFK 58 74 67 83 / 100 70 10 20 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 29/19/07