Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/29/19

National Weather Service Albany NY
959 PM EST Mon Jan 28 2019 .SYNOPSIS... A storm system will approach the region tonight, allowing clouds to increase overnight. This system will bring widespread plowable snow to the region Tuesday through Tuesday night. An arctic airmass arrives in the wake of the storm system, resulting in dangerously cold temperatures Wednesday through Friday. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Updated at 945 pm. Mainly clear skies with light winds have allowed temperatures to fall quickly this evening, with readings at 9 pm ranging from the single digits to near zero near and north of Albany, to the teens in the mid-Hudson Valley. Clouds are spreading eastward across central NY and will overspread our area shortly after midnight with temperatures remaining steady or slowly rising late tonight. A quick look at the latest HRRR and 00z NAM forecasts indicate little change in the overall thinking with our upcoming storm. Light snows are still expected to reach areas of west of the Hudson Valley toward daybreak. Light snow will persist into the afternoon across areas west of the Hudson Valley and also in the upper Hudson Valley north of the Capital District with downsloping southerly winds resulting in just spotty flurries farther to the south. Steadier, heavier snow will organize across the entire area by late afternoon as a wave of low pressure moves north from the mid-Atlantic toward southwest New England. Watches will be converted to either warnings or advisories based on additional incoming guidance expected through midnight. For now there remains enough uncertainty on snowfall totals in the Capital District so that watches will remain in effect until all of the 00z guidance is in. Previous discussion is below... Clouds increase tonight and the leading edge of light snow should reach western areas by daybreak. The period of clear sky and light winds this evening will allow temperatures to fall into the single numbers to low to mid teens for lows, then become steady and maybe rise a degree or two toward daybreak. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... Winter Storm Warning for the Southern Adirondacks, western Mohawk Valley, and Lake George Saratoga Region and Southern Vermont... Winter Storm Watch is in effect for the Greater Capital District, northern and central Taconics, mid-Hudson Valley including eastern Green and western Columbia counties, Washington county of eastern New York, as well as the Berkshires of western Massachusetts... The storm system that will be affecting us Tuesday through Tuesday night is not a conventional snow storm. The leading edge of the snow will reach the southern Adirondacks and eastern Catskills first, late tonight, then spread across the rest of the region around or just before daybreak through Tuesday morning as low level jet convergence, warm advection and isentropic lift increase. Upslope process will enhance snowfall in the southern Adirondacks, northern edge of the western Mohawk Valley and Lake George Saratoga Region. Downslope flow could limit snowfall amounts in the Schoharie Valley, central and Western Mohawk Valley, Capital District, and Hudson Valley. There is considerable disagreement in liquid equivalent precipitation forecasts from sources of guidance/ensembles with some guidance that has shown considerable reliability in the past showing liquid equivalent amounts limited to the point that areas currently still under winter storm watches may not reach 6 to 7 inches but other guidance suggests those amounts even in valleys with slightly higher amounts in higher terrain. There are also some indications in sources of guidance that there will be a period Tuesday afternoon and evening that the strongest vertical motion extends well through the dendritic growth zone over eastern NY and western New England, which could result in better snow ratios and convert to more snow regardless of the relatively low liquid equivalent. With all these conflicting factors, winter storm warning were issued only in the areas of the highest confidence, in the areas of upslope into higher terrain of the southern Adirondacks, eastern catskills and southern VT. Watches were left up where they existed already and can be converted to either advisories or low end warnings based on the new set of guidance expected tonight. The Poughkeepsie area to Litchfield Hills may get advisory level snows and those headlines will be considered with the latest guidance as well. Climatological snow maps based on multiple storms with strong southwest boundary layer flow suggest there could be quite considerable differences in snow amounts in short distances between valleys and terrain, which was also a factor in keeping watches up where the confidence in reaching 6 to 7 inches was lowest. The Helderbergs may get 7 or more inches while the Capital region may see 4-7 inches. So, again, some of these uncertainties should get cleared up overnight with the newest guidance. There may be a mix with rain in the Poughkeepsie area and Litchfield Hills Tuesday afternoon as well before going to all snow Tuesday night. Again, the complicated watches and warnings and varying start and end times will be consolidated after the latest guidance clears up the lingering uncertainties overnight. Highs Tuesday in the 30s but some 20s northern areas. Snow ends Tuesday night and an initial push of colder air spreads into our region. A strong upper low and leading edge of much colder air tracks through our region Wednesday with the potential for snow showers and squalls on the leading edge of the Arctic air. The low and midlevel lapse rates look quite steep along the cold front. Highs Wednesday in the teens to lower 20s but some mid 20s southern areas and some single number northern areas. Windy and cold Wednesday night with most areas at or below zero and wind chill advisories and warnings may be needed with wind chills less than 15 below and as cold as 30 to 40 below. Highs Thursday in the single numbers to lower teens with continued breezy conditions. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... The long term forecast period will begin with lingering lake effect snow over the western Adirondacks and bitter cold temperatures over the entire region. High pressure builds in for a portion of the weekend before another low pressure system approaches from the Great Lakes region late Sunday or early next week. Thursday night through Friday...Lake effect snow over the Adirondacks will begin to retract and diminish late Thursday through Friday due to boundary layer flow becoming disrupted as a short wave trough swings through the northern periphery of the region. Some light snow accumulations of around an inch will be possible overnight Thursday into Friday morning over Herkimer county. Blustery conditions will continue Friday with 850-hPa temperatures between -15 and -20 C. Wind chills will continue to be well below zero in the negative teens and twenties. Wind chill headlines could be needed to address these dangerously cold temperatures. Saturday through Monday...Mid level ridging will build into the region late Friday into Saturday with the associated subsidence resulting in surface high pressure. Temperatures Saturday morning will begin cold near zero and moderate into the teens and twenties by Saturday afternoon with partly cloudy skies. Global guidance suggests that a shortwave trough digs into the Midwest CONUS Sunday into Monday with surface cyclogenesis commencing shortly after. The surface low looks to develop over the Midwest with the warm front extending to the east over the NE CONUS late Sunday into Monday. This could result in precipitation beginning Sunday evening, but the precipitation types are very much up in the air as of now. Guidance suggests mostly rain for the region as of now but this will be highly dependent on the track of the system and whether or not the warm sector overspreads our region. Highs Sunday will be near normal in the upper 20s and low 30s. Highs Monday will continue to moderate into the upper 30s to low 40s. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... High pressure will dominate early in the TAF period, giving way to an approaching low pressure system from the western Great Lakes. VFR conditions are expected through at least 12Z Tuesday, but clouds will thicken and lower throughout the night. Snow is expected to begin over the TAF sites in the morning or early afternoon. The timing and intensity of the snowfall is the main challenge for this TAF issuance. Isentropic lift will bring snow to the higher terrain beginning around 09Z Tuesday, but forecast soundings suggest it will take longer to saturate over the TAF sites. So we will mention VCSH beginning at 12Z with cigs/vsby falling to MVFR by 15Z. It appears the heavier snow will occur after this TAF period. The exception may be over KGFL which could see IFR conditions by around 15Z in steadier snowfall. Winds for the remainder of today will be generally from the northeast at 5-12 kt with some gusts near 20 kt at KPOU possible. Winds will become light and veer to southeasterly early tonight, increasing to 5-10 kt late tonight into Wednesday morning, with some gusts to 20 kt possible at KALB/KPSF. LLWS conditions will be possible at KPOU/KGFL after around 09Z where surface winds are expected to be lighter as 2kft AGL winds increase to 30-35 kt from the south. Outlook... Tuesday Night: High Operational Impact. Definite SN. Wednesday: Moderate Operational Impact. Breezy Chance of SHSN. Wednesday Night: Low Operational Impact. Breezy NO SIG WX. Thursday: No Operational Impact. NO SIG WX. Thursday Night: No Operational Impact. NO SIG WX. Friday: No Operational Impact. NO SIG WX. Friday Night: No Operational Impact. NO SIG WX. Saturday: No Operational Impact. NO SIG WX. && .HYDROLOGY... The next chance for widespread precipitation arrives with a strong storm system Tuesday into Wednesday. Precipitation will be in the form of mostly snow, but may mix with rain in the mid- Hudson valley into northwest Connecticut. Total QPF with this storm looks to be around 0.5 to 0.75" with just over an inch possible in the southern Adirondacks. Water levels will slowly recede, but ice jams will continue to freeze in place. Lake effect snowfall will impact the western Adirondacks into the Mohawk Valley Wednesday through Thursday night. 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...Winter Storm Warning from 1 AM Tuesday to 4 AM EST Wednesday for NYZ032-033-038-039-041-042-058-063-082-083. Winter Storm Watch from Tuesday afternoon through late Tuesday night for NYZ043-053-054-060-061-084. Winter Storm Watch from 5 AM EST Tuesday through late Tuesday night for NYZ040-047>052-059. MA...Winter Storm Watch from Tuesday afternoon through late Tuesday night for MAZ001-025. VT...Winter Storm Warning from 1 PM Tuesday to 7 AM EST Wednesday for VTZ013>015. && $$ SYNOPSIS...NAS NEAR TERM...MSE/NAS SHORT TERM...NAS LONG TERM...Cebulko AVIATION...Thompson HYDROLOGY...NAS
Area Forecast Discussion
National Weather Service Boston/Norton MA
1053 PM EST Mon Jan 28 2019 .SYNOPSIS... High pressure will bring dry and cold weather tonight as it builds across New England and heads to the Maritimes. Low pressure is expected to track across s New England Tuesday night, bringing a mix of snow and rain to much of the area, with the heaviest snow to the Berkshires and north central Massachusetts. Bone chilling cold late week into the early weekend, a mild pattern is forecast beginning Sunday into the following week with chances of rain and/or snow. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 1015 PM Update... Winds have shifted to N-NE along the immediate coast from about Boston southward to Cape Cod and the islands over the last few hours. Low ocean clouds have worked onshore from Cape Ann to Cape Cod, even with light N winds across Essex county into portions of central Merrimack River valley. Previous forecast suggested that, with onshore winds, will see ocean effect snow showers develop from about midnight onward, mainly from Boston northward. However, still noting dewpoints in the single digits from KBOS-KOWD north and west ward, but have risen to the mid teens to around 20 across SE Mass, Cape Cod and the islands. Even there, still noting T/Td spreads of around 10 degrees. Also noting no echoes reported on the TBOS 0.3 degree radar reflectivity so far. So, decided to back off on the ocean effect snow showers mentioned in the previous forecast. Did keep snow flurries by around 06Z near the immediate shoreline. Once winds veer to E-NE near and N of Boston to the north shore, may start to see spotty snow showers develop as the low level moisture increases mainly around or after 09Z. Remainder of the forecast was in good shape, but did update to bring conditions current. Previous Discussion... Beneath the veil of high clouds per nighttime satellite micro- physics, marine stratus clouds lurk. Decent low-level dry air, absent outcomes per HRRR signaling a red flag, do not expect much in the way of accumulation and little to no impact to visibility. Some impact to 2m temperatures with encroachment of low clouds into E/SE MA along with onshore flow coupled with the mid to upper level cloud shield courtesy of offshore synoptics associated with a frontal wave of low pressure. Mild conditions with lows in the 20s as a result. The rest of S New England with lows getting into the teens under clear conditions. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/... */ Highlights ... - Winter Storm Watch for East Slopes of Berkshires/N Worcester County Tue afternoon into Wed Morning */ Discussion ... Our winter storm then arrives during the day Tuesday. A deep mid level shortwave and surface low pressure system will sweep through the northeast Tuesday-Wednesday. Models agree that the parent low stays well to our northwest, while a secondary low forms along the initial cold frontal boundary as it approaches southern New England. This doesn`t look to be a hugely impactful storm from the perspective of low elevation snow, winds, or coastal flooding due to the inland track and the delay in deepening of the low until it reaches New England. The track that has come into focus over the last few model runs takes this low directly over SNE or even slightly north. As such it`s quite warm and while most will start as snow, S/SE winds quickly bring in above freezing air at the surface which will change snow to rain up to generally a line from Hartford to Worcester to Lawrence. Further to the northwest where the below freezing air holds on snow should continue through the event. Expecting generally 6-8 inches in the Berkshires by the time precip moves out before 7 am Wednesday; 4-6 inches in the higher elevations of the Worcester Hills. These locations with the highest probability of staying purely snow are where Winter Storm Watches continue. One area of uncertainty remains in just how quickly and far north the warm air at the surface will make it late Tuesday. Not a classic CAD setup, given the high north of us is offset to the east, but hi-res guidance still wants to signal some of that cold air drainage keeping portions of the CT river valley and portions of northern MA colder than currently forecast. Something to watch as we get closer to the event. As the low picks up steam, downstream colder air wraps around on the backside and will probably switch everyone back to a brief period of snow as the system exits early Wednesday morning. As mentioned previously, the low really doesn`t begin to deepen until it is over or north of SNE and as such 925 mb winds don`t ramp up more than 25-35 kts until it is downstream of us. We can expect wind gusts of 20-25 kts overnight, mainly along the coasts. On Wednesday, the storm moves offshore and ushers in a period of very efficient CAA as a broad mid-upper level trough moves overhead. 850 mb temperatures drop from around -3C Tuesday evening to around -24 C late Wednesday. This will promote good mixing down of a 35-45 kt LLJ moving overhead during the day. Model soundings indicate potential for wind gusts of 30-40 kts. Highs in the upper 20s will feel more like the low teens. Another thing to monitor Wednesday will be an arctic front that moves through from west to east during the afternoon and evening hours. This will bring the potential for some brief but intense snow squalls that could be hazardous to those on the road. As the front sweeps through, a band of saturated air in the BL and lots of low level instability accompanies it...1000-700 mb lapse rates approach 9 C/KM along and ahead of the front which could lead to brief but intense heavy snow, low visibilities, and gusty winds. Behind the front temperatures will plunge as we head into Wednesday night. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... */ Highlights ... - Bone chilling, record-breaking cold late week into weekend - WIND CHILL headlines likely - Pattern shift into early February, mild with zipping SW-NE storms - What side of the envelope, difficult to say on outcomes */ Overview ... Pattern shake-up. W retreat H3 Pacific jet buffered by sub-tropical Pacific activity echoing poleward. Latent heat release and higher heights, favorable N Pacific low development shifts over Russia`s Kamchatka Peninsula. Noting 5-day ensemble means, H5 split flow out over the NE Pacific / Gulf of Alaska, W CONUS H5 trof promotion with SW winds across the CONUS. Recent S-carving PV-anomalies across E/NE N America shunted N, favorable region of storm developments shifts towards S Greenland. This as the stratospheric polar vortex (10 mb) tightens up over the N pole. So how does this play out for New England in the long run? Will be watching for any surge of anomalously warmer sub-tropical W/SW winds yielding +H85 temperature anomalies as the ECens suggests into early February. But challenges into an ongoing phase 5-6 MJO into phase 7, strength / magnitude of sub-tropical Pacific activity in question, unclear the impact along with inherent challenges in forecasting. A nod to NE Pacific split-flow regime, how energy echoes downstream through a preferred W CONUS trof and, at times, anticyclonic wave breaks extending from Hawaii into western N America. The latter, an eye on H85 westerly anomalies already noted S/E of Hawaii just N of the equator. Seemingly along the thermal-cusp, will be watching for SW-NE weak open-wave zipping lows, wobbling, wavering, a challenge to forecast. New England will be a precip-type playground into the first week of February. Unclear whether we tap into forecast +H85 temperature anomalies, or are cut down by undercutting NE-winds with prevailing preferred high pressure over SE Canada. Break down details, forecast thinking below. Greater weighting towards EC / ECens as always. */ Discussion ... Wednesday night through Saturday night ... Cold. Plain and simple. Stout potential vorticity anomaly / trop- fold contributing to deep surface cyclogenesis across Quebec. The isallobaric / gradient wind response driving Arctic air across the NE CONUS into the weekend. Have to watch for WIND CHILL headlines for late Wednesday through Wednesday night, possibly through as late as Friday. Cold air advection, steepening lapse rates over time up to around H7 beneath the trop-fold 0z Thursday, will also have to watch winds, efficiency for the top of the mixed layer to mix down, whether we`ll need WIND HEADLINES in addition to some scattered snow shower activity. H85 temperatures falling down around -25C, can`t rule out record-breaking H925-7 temperatures within Chatham sounding profiles per climatology. A 1030+ high Saturday morn, cold exacerbated by radiational cooling, especially for areas with deeper snowpack. May come close to record lows, but a better shot of breaking record lowest high temperatures. Sunday onward ... SW-NE weak zipping lows grasping on conduits of sub-tropical air while training along wavering thermal gradients. Little confidence on outcomes, will have to wait and see. Numerous variables as to whether snow pack remains which, if any undercutting cold NE flow prevails in advance, would aid in maintaining frozen precip-types. Expecting forward-thump, isentropic-upslope, baroclinic leaf events with SW-NE lows. Generally weak, fast, with a possible decent sub- tropical fetch, anywhere from snow to rain, just depends which side of the envelope S New England will reside upon. && .AVIATION /04Z TUESDAY THROUGH SATURDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday/...Moderate confidence. Overnight... Mainly VFR, except MVFR CIGS from 2000-2500 ft across E coastal terminals, which will push westward to the KOWD-KPVD corridor. Can`t rule out flurry activity with minor VSBY impacts along the immediate coast from about KBVY-KGHG from around 08Z-12Z. MVFR CIGS push further W across the interior towards Tuesday morning. Tuesday into Tuesday night... MVFR becoming widespread, lowering to IFR-LIFR with onset SN. Impacts spreading W to E roughly 16-21z. S-coastal locations remaining as RA, the transition RA / SN line progressing as far N as BDL-ORH-BVY roughly 4z before changing back to SN. Lower VSBYs with SN. Blustery E/SE flow, however may see some N drainage winds within interior valleys throughout before winds shift W by Wednesday morning. Wednesday... Blustery W winds, gusts of around 25 to 35 kts, possibly as high as 40 kts. SCT-BKN low-end VFR CIGs around 040, the threat of SN/+SN showers with briefing IFR-LIFR impacts and quick snow accumulations on any and all surfaces. KBOS Terminal... MVFR CIGs developing this evening, could be some attendant snow flurry activity, however thinking little to no impact to VSBYs. Will see bigger SN impacts towards the afternoon into evening push Tuesday. KBDL Terminal... Quiet night, but expect lower conditions to work in closer to noon Tuesday with onset SN. IFR-LIFR prevailing through the Tuesday PM push. Outlook /Wednesday Night through Saturday/...Moderate Confidence Wednesday Night: VFR. Strong winds with local gusts up to 40 kt. Thursday through Saturday: VFR. Breezy. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday/...High confidence. Tonight ... High pressure builds over waters tonight with N/NE winds. Tuesday into Tuesday night ... Increasing SE flow Tue as high pressure heads to Maritimes and low pressure tracks through eastern Great Lakes. Expect a weaker low to develop Tue night and track through southern New England. Winds should reach SCA on most of waters with gusts of 25-30kt possible. Wednesday... Strong west winds increasing to 35-45 kts. Seas building to 9-11 ft on the southern waters, 6-8 ft on the eastern waters. Arctic air sweeping in, the threat for moderate freezing spray by late Wednesday. Outlook /Wednesday Night through Saturday/...Moderate Confidence Wednesday Night: Low risk for gale force winds with local gusts up to 45 kt. Rough seas up to 12 ft. Freezing spray likely, slight chance of snow showers. Thursday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Freezing spray likely, slight chance of snow showers. Thursday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Freezing spray likely. Friday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Local rough seas. Freezing spray likely. Friday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Freezing spray likely. Saturday: Winds less than 25 kt. Seas locally approaching 5 ft. && .CLIMATE... Record LOWEST High Temperatures for Thursday, January 31st... Boston ....... 12 (1920, 1935) Hartford ..... 15 (1951) Providence ... 15 (1935) Worcester .... 11 (1951) && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...Winter Storm Watch from Tuesday afternoon through Wednesday morning for MAZ002>004-008-009. RI...None. MARINE...Gale Watch from Wednesday afternoon through late Wednesday night for ANZ231>235-237-250-251-254>256. && $$ SYNOPSIS...Sipprell/BW NEAR TERM...Sipprell/EVT SHORT TERM...BW LONG TERM...Sipprell AVIATION...Sipprell/EVT/BW MARINE...Sipprell/EVT/BW CLIMATE...Staff
Area Forecast Discussion
National Weather Service Louisville KY
945 PM EST Mon Jan 28 2019 .Forecast Update... Issued at 945 PM EST Mon Jan 28 2019 Surface cold front continues to push eastward through the US 27/127 corridor and will push through Frankfort shortly and then through Lexington in the next couple of hours. Precipitation has been showing a diminishing trend on radar as upper support pulls off to the northeast. Back edge of precipitation is just ahead of the freezing line which is approaching the I-65 corridor. We`ve seen a mix of sleet and snow with this precipitation, though as the colder air has grown deeper, the mix was very short lived and went over to snow rather quickly. The snow is rather light and really has not accumulated at all. Overall forecast remains on track. We`ll see precipitation shield head on off to the east over the next few hours with colder air pushing from western KY through the remainder of the state overnight. Probably will see a batch of flurries pass through southern IN and parts of N/C KY this evening and into the early overnight, but again, no real accumulations are expected. Did a quick refresh of the Special Weather Statement that was issued earlier. We`ll have some wet roadways across the region this evening and with temps dropping into the teens overnight, some icy spots will be possible. Road temps are running above freezing and there will be a lag before they drop down below freezing. Combination of much drier air, gusty northwest winds, and some traffic on the main road will likely allow them to dry out a bit this evening and into the overnight. However, secondary roads that are protected from the wind and less traveled could see some black ice overnight. Issued at 841 PM EST Mon Jan 28 2019 Surface cold front has pushed just east of the I-65 corridor this evening. Band of light rain showers continues in advance of the front and will produce about 0.02 to 0.04 inches of rainfall as it sweeps eastward across central KY this evening. Temperatures have fallen into the lower 40s in areas east of I-65. Just west of I-65, temps have fallen into the lower 30s with the freezing line along a line near Owensboro south westward to near Paducah. Just behind the front, we do have about a 20 mile wide band of light precipitation. This is likely a mix of sleet and some light snow flurries. With temps still above freezing, we`re not expecting much of any accumulation, sans a quick deck duster or rooftop dusting. Colder air will continue to work into the region this evening, with the freezing line likely reaching the I-65 corridor in the next hour or so and then quickly racing eastward toward the I-75 corridor by midnight. Issued at 631 PM EST Mon Jan 28 2019 Surface cold front has just pushed through southwestern IN and is entering far northwestern KY. Out ahead of this front, widespread light rain showers are occurring and will likely drop between 0.01 and 0.04 inches of rainfall as they move through. Based on radar observations, not much rainfall is occurring behind the front, so a brief change over to snow still looks possible in the I-65 corridor this evening, but that window looks to be closing fairly rapidly. Actual freezing line is trailing back behind the front by 50-60 miles or so. That freezing line will reach in the IN/IL border shortly and then push into KY this evening. Latest HRRR runs seems to have captured this feature well and push the freezing line toward the I-65 corridor by 10 PM or so and then into the I-75 corridor by midnight. && .Short Term...(This evening through Tuesday) Issued at 315 PM EST Mon Jan 28 2019 A narrow rain band along a cold front curved from IND to EVV to PAH this afternoon, with hints of sprinkles/virga on radar out ahead of the primary band. Upstream, cold air has been lagging the precip all day. And GOES-16 low level water vapor imagery shows the dry slot that will shut off precip fairly quickly tonight. Overall, it looks like a brief period of light to moderate rain at any one spot. Some areas could see precip end as a very brief period of light snow, but this shouldn`t amount to much. In addition, temperatures have surged into the mid 40s to mid 50s this afternoon. At least some of any brief snow will likely be lost to melting. However, strong CAA will be underway during the 00-06z time frame. Mid-level PVA could help enhance the post-frontal precip slightly. If a band of snow could develop on the western edge of the deeper moisture plume, some spots could pick up a dusting. However, most locations will see little to no accumulation. So have cancelled the Winter Weather Advisory. Temperatures dropping into the mid teens to lower 20s Tuesday morning could also create some slick spots with any lingering moisture/dusting of snow. Otherwise, Tuesday will be chilly and breezy. Temperatures won`t make it out of the 20s. A deep, highly anomalous upper low will continue to rotate southeast over the Great Lakes on Tuesday. Arctic high begins to build SE, sending even colder air our way Tuesday evening. .Long Term...(Tuesday night through Monday) Issued at 415 PM EST Mon Jan 28 2019 ...ARCTIC AIR FOR MIDWEEK... The big story during the extended is the intrusion of arctic air into the Ohio Valley for Wednesday and Thursday. Temperatures will plummet to the single digits - above and below zero - for all but the far southern Kentucky counties by sunrise Wednesday, and again on Thursday morning. For southern Indiana, daytime highs on Wednesday will remain in single digits. The extreme temperatures, along with northwest winds 10-15 mph through midday Wednesday, will result in wind chill indices of -10 to -20 Fahrenheit into the early afternoon. While there will be some sunshine to go along with the frigid air, make no mistake - this will be COLD! For that reason, we`ve gone with a Wind Chill Advisory from 07Z to 19Z Wednesday. While some VERY light snow of flurries could fall overnight as the cold air arrives, this dry snow will be more flurries than anything else, with only trace amounts expected. Almost as quickly as it arrives, the cold air will move out during the latter half of the week. WHile Thursday morning temperatures will be as cold as - or colder than - Wednesday morning lows, the winds will be lighter as the ridge of high pressure associated with the cold drifts over the area. By Thursday afternoon, the surface high and thermal trof will have passed to the east, and return flow from the south will start to moderate temperatures. As the warm air moves in to replace the cold air, there is another chance of snowfall Thursday night into Friday morning. While it is possible some locations could pick up an inch of accumulation, it will be short lived, as temperatures push above freezing by late morning, topping out in the upper 30s to lower 40s by afternoon. Saturday will be dry, but another chance for rain comes in with the warmer air on Sunday. Temperatures continue to rise through the weekend with highs in the upper 40s and 50s Saturday, and in the 50s to around 60 Sunday and Monday. && .Aviation...(00Z TAF Issuance) Updated at 625 PM EST Mon Jan 28 2019 Early evening surface analysis reveals surface cold front just entering the WFO LMK forecast area. The front just pushed through KHNB and is heading eastward. Out ahead of of it light rain is being reported and will continue for a time this evening. Winds out ahead of the front have been from the southwest and will continue to be gusty this evening. Sustained winds of 15-20kts and gusts to 30kts will be possible at times. Ceilings will start off VFR, but will likely drop into the MVFR range this evening. Visibilities look to remain generally VFR. Cold front looks to push through KSDF/KBWG between 29/00-01Z and then over at KLEX around 29/03-04Z. Precipitation is likely to end just after frontal passage and we could see a very brief period of snow at KSDF/KBWG, but it is not expected to amount to much. Some light snow would be possible over at KLEX toward midnight if precipitation lingers long enough to get caught up with the approaching cold air. Behind the front, look for winds to shift around to the west/west- northwest and they will remain gusty. Current thinking is that winds will remain around 280/290 degrees with sustained speeds of 12- 15kt with gusts to 25 kts at times. Ceilings look to remain around 2200-2300ft AGL in the post frontal flow. Winds should slacken off late tonight with ceilings improving to VFR after 29/12Z. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...Wind Chill Advisory from 2 AM EST /1 AM CST/ to 2 PM EST /1 PM CST/ Wednesday for INZ076>079-083-084-089>092. KY...Wind Chill Advisory from 6 AM EST /5 AM CST/ to 1 PM EST /noon CST/ Wednesday for KYZ023>043-045>049-053. && $$ Update.......MJ Short Term...EBW Long Term....JBS Aviation.....MJ
Area Forecast Discussion
National Weather Service Nashville TN
815 PM CST Mon Jan 28 2019 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... Well, we`re creeping up on game time here and it`s not looking good. With the progression of the current precipitation on radar, along with temperatures still in the 40s and low 50s across all of Middle TN, combined with the latest HRRR guidance, we`re going to back of considerably on the snowfall totals and trim a couple more counties off the back side of the Winter Weather Advisory. I will, however, maintain the Cumberland Plateau in the Advisory from midnight until 6 am. This means we`ll also be reducing the total number of hours of the advisory (removing 6 am - noon), as latest guidance also has all of the precipitation east of Middle TN by 6 am. This doesn`t negate the eventual arrive of pretty cold air into Middle TN tonight. It`ll just be later than guidance had us believing. Single digit wind chills north of I-40 and teens elsewhere will be here in the morning. Updates will be out shortly. && .AVIATION... 00Z TAF DISCUSSION. BNA/MQY/CKV/CSV...A strong cold front is making its way across Middle Tennessee this evening, but it`s coming through a lot drier than previously forecast. Look for light precipitation this evening, mainly behind the surface front, mixing with and then changing to snow before ending. Ceilings will drop to MVFR for a few hours before improving later tonight or early Tuesday morning. Precipitation will be a little heavier and ceilings a little worse farther east, so CSV will experience lower visibilities and ceilings than the rest of our terminals. && .OHX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from midnight tonight to 6 AM CST Tuesday for Cannon-Coffee-Cumberland-De Kalb-Fentress-Grundy- Overton-Pickett-Putnam-Van Buren-Warren-White. && $$ DISCUSSION......Unger AVIATION........08