Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/15/17

Area Forecast Discussion
National Weather Service Taunton MA
1030 PM EST Sat Jan 14 2017 .SYNOPSIS... Weak low pressure slides well S of the coast tonight. Light snow along the South Coast will move offshore during the night. High pressure maintains dry and seasonable conditions Sunday and Monday. Low pressure from the Plains approaches Southern New England with rain and mild air for Tuesday and Wednesday. The low then redevelops to our east and moves off Wednesday night. High pressure then builds in with dry and continued mild weather for the end of the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... 1030 PM update... Large dew point depressions in the lower levels keeping most of southern New England from seeing a more significant light snow. Northern edge of the precipitation was along the immediate south coast of MA and RI, and continuing to move east. Expecting the radar returns to completely move out before 1 AM EST. Most locations only reporting a dusting of accumulation, at most. Lowest visibility in the more significant snow was about 2 miles. Brought the forecast back in line with observed trends. Otherwise, no major changes to the ongoing forecast. Previous discussion... Winds have shifted to S-SE though remain light across the region. They may back to a SE direction along the S coast, which may allow enough low level moisture, even with the low dewpts, to bring some spotty light snow along the S coast of MA/RI overnight. NAM 4 KM, RAP and GFS BUFKIT soundings are signaling light snow reaching into KEWB, KCHH and KHYA overnight, and even for a few hours as far N as KPVD. Think it will be tough to get it into KPVD at this point, but still a shot along the coast. Models are suggesting that dewpts do rise as the northern edge of the precip pushes across, but they have had a warm bias all day today, so not confident they will rise as quickly as the models are suggesting. Have CHC POPs hugging along the S coast through around 06Z, then should exit quickly as another high starts to push E out of the Great Lakes. Strong mid and upper level jet across the region with W-NW winds up to 135 kt at H3 on 12Z KCHH sounding and 140 kt at H25 on KALB sounding. Short range models all show this sitting across the region overnight, then pushing E after 06Z Sun. Skies should start to clear across N central and W Mass after 10 PM or so, then will quickly shift eastward overnight pushing toward the S coast toward daybreak. Winds shift to W-NW with the approaching high. Expect temps to bottom out in the teens across most areas, except in the 20s along the immediate coast. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Sunday... While high pressure moves E across W NY state early Sunday, a second high will shift E out of central Quebec. This will bring a reinforcing shot of cold air across the region during the morning. Noting a 30-40 kt jet shifting SE from H85 to H9 as the front approaches. Will see good low level mixing push into the region from H92 and below, especially across the waters by around midday and through the afternoon. Expect mainly clear skies across most of the region, but some clouds will linger across the E slopes of the Berkshires. H92 temps drop to -5C to -9C by 15Z Sun then level off at -5C to -7C during the afternoon. Should see high temps from the mid 20s to around 30 across the higher inland terrain to the upper 30s along the S coast. Sunday night... Large high pressure center will slowly cross NY state/PA, with N-NW winds diminishing during the night. Expect mainly clear skies through the night and, as the winds drop off, will see temps fall as well with good radiational cooling setting up. Expect overnight lows ranging from 5 to 15 across most areas, ranging to the upper teens and 20s along the immediate coast and urban centers. && .LONG TERM /MONDAY THROUGH SATURDAY/... Big Picture... Hudson Bay upper low retreats north, leaving a large-scale zonal flow for much of the long term. Toward next weekend the large scale a developing Pacific Coast trough and West Atlantic Ridge. In the shortwave scale, Baja California upper low ejects through the Southern Plains Monday and Great Lakes Tuesday, then New England Wednesday. East Coast ridge then builds late week. Contour heights are mostly forecast to be above the climatological average. GFS does show heights briefly near normal Wednesday as the upper trough moves past, but the ECMWF and GGEM are much warmer. Overall this looks like a dry mild week, punctuated by a period of rain Tuesday-Wednesday. Model mass fields are similar through Wednesday morning, then diverge in handling the midweek weather system. They then show a general agreement on high pressure arriving for Friday and Saturday. Confidence for the long term is moderate. Details... Monday... High pressure settled offshore, bringing a light west to southwest flow. The mixed layer reaches to about 950 mb, where temps support max sfc temps of 35 to 40. Some increase in cirrus at night, especially across CT and RI, but otherwise fair skies and light winds. This will allow radiational cooling for a portion of the night. Dew points 15 to 30 should allow min temps mainly 20-30. Tuesday-Wednesday... Models are trending slower with the onset of clouds and precipitation. The lower airmass remains dry through midday while mid and high clouds are on the increase. Low level ageostropic flow turns from the north but remains 20 knots or less. Meanwhile temps will have time to climb above freezing in most places. If cold air does linger, it would be most likely in some of the East Slope communities of Northwest MA. There also remains a chance that the combination of slightly stronger drainage flow and evening evaporative cooling could bring a period of freezing rain in Northwest MA. This will need to be monitored. Aside from that potential icing scenario, temperature profiles suggest rain for our area from onset to finish. Models are showing a coastal redevelopment of the system on Wednesday, but disagree on the location. The GFS says Gulf of Maine while the ECMWF says Long Island. The GGEM tries to do a little of both. Still plenty of time for these details to sort out. Thursday through Saturday... The ECMWF shows a second shortwave sweeping down from Canada Thursday while the GFS shows, at best, a very shallow version of one. This may be good for snow showers in the hills, but moisture profiles are sufficiently dry to maintain a dry forecast. High pressure then builds in for Friday and Saturday. Temps in the projected mixed layer support max sfc temps in the 40s. Dew points are projected in the upper 20s and 30s, supporting lows in the 30s. && .AVIATION /04Z SUNDAY THROUGH THURSDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday Night/... Tonight...Moderate confidence. VFR conditions continue across most of the region. An area of snow moving along the South Coast and Islands will bring a period of MVFR cigs/vsbys, briefly reaching IFR vsbys in the steadiest snow. Movement of the snow would project it moves east of Cape Cod and Islands 04Z to 06Z. SW winds shift to W for a time overnight, then NW toward morning. Winds may gust up to 20 kt on outer Cape Cod as winds shift after midnight. Sun...High confidence. VFR. NW winds gusting to 20-25 kt along the immediate E coast, Cape Cod and the islands through early afternoon, then diminish. Sunday night...High confidence. VFR. KBOS TAF...High confidence in TAF. KBDL TAF...High confidence in TAF. Outlook /Monday through Thursday/... Monday...High confidence. VFR. Tuesday-Wednesday...Moderate confidence. VFR Tuesday morning, lowering to MVFR cigs/vsbys in rain Tuesday afternoon/evening, then IFR in rain and fog Tuesday night and Wednesday. Conditions may improve Wednesday afternoon. Variable winds Tuesday becoming S-SE Tuesday night, S-SW Wednesday, and West by Wednesday afternoon. Thursday...Moderate confidence...VFR. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday Night/... Tonight...High confidence. Light SW winds increase overnight. May see gusts to 20 kt on the eastern open waters after midnight as they shift from the NW. Seas 4 ft or less. Some brief visibility restrictions across the southern waters to SE of Cape Cod in light rain and/or snow, ending after midnight. Sunday...Moderate to high confidence. NW winds gusting to 25 kt on the eastern open waters and Mass/Ipswich Bays. Seas may reach 5 ft there as well. Small craft issued. Winds should diminish on the near shore waters around midday, but will linger on the outer waters through the day. Sunday night...High confidence. Any leftover NW wind gusts to 25 kt will diminish Sunday evening on the eastern outer waters. Seas should also subside below 5 ft. Outlook /Monday through Thursday/...Moderate confidence. Monday-Tuesday...Winds less than 20 knots and seas less than 5 feet. Tuesday night-Wednesday...Southeast winds reach 25 knots on the outer waters and possibly RI Sound, with seas building to 5-7 feet. Best chance is on the southern outer waters. Small Craft Advisory may be needed on these waters. Visibility will be reduced in periods of rain Tuesday night, with rain tapering off as winds shift from the West Wednesday afternoon. Thursday...Northwest winds will gust to 25 knots on some of the waters. Seas of 5-7 feet will slowly diminish during the afternoon. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 6 AM to 9 PM EST Sunday for ANZ250- 254. Small Craft Advisory from 6 AM to 1 PM EST Sunday for ANZ251. && $$ SYNOPSIS...WTB/EVT NEAR TERM...WTB/Belk/EVT SHORT TERM...EVT LONG TERM...WTB AVIATION...WTB/EVT MARINE...WTB/EVT
Area Forecast Discussion
National Weather Service Columbia SC
941 PM EST Sat Jan 14 2017 .SYNOPSIS... A stalled boundary in the southern portion of the area will become diffuse and move back north Sunday, bringing a return to higher temperatures. An upper ridge over the southeastern part of the country will favor above normal temperatures through midweek. Another front will bring showers and possible thunderstorms late Wednesday and Thursday. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... A stalled frontal boundary along the southern portion of the forecast area will become diffuse overnight. Fog will be the main forecasting concern with some potential for dense fog. Moisture near the surface coupled with nocturnal cooling is already resulting in some fog development this evening particularly in the CSRA. Dense fog potential may be limited by high clouds and a 20 knot low level jet. Well above normal overnight low temperatures are forecast, in the upper 40s to near 50. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... Weak high pressure will reside over the area early Sunday with yet another backdoor front pushing into the forecast area from the northeast later Sunday and Sunday night beneath a building upper ridge over the southeastern states in response to the eastward ejection of the southwestern US cutoff upper low. Isentropic lift over the northern Midlands Sunday night into Monday morning and will carry slight chance for light rain during this period. Otherwise generally fair weather is expected with continued above normal temperatures. Sunday will be mild with highs ranging from the mid 60s northern Midlands to the lower 70s southern Midlands and CSRA. Monday, behind another backdoor cold front, will be cooler with highs ranging from the upper 50s northern Midlands to upper 60s in the CSRA. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Uncertainties continue in the extended period because of differences in the medium-range models of the timing of a series of upper-level disturbances moving across the area from the west especially towards the end of the week. Medium-range models and ensembles appear to be in reasonable agreement with the overall large scale pattern during this period showing a mean trough over the west and somewhat flat ridge over the east. However, differences in the details leads to the uncertainty with this forecast. Deep south-southwesterly flow develops over the area Tuesday through Tuesday night over the area ahead of a cold front extending across the Ohio/Mississippi Valleys being driven by a closed low over the upper midwest. Upper-level energy lifting out of the southern Plains will push across the Southeast for much of the remainder of the week. Chance pops look reasonable for much of the period, with thunder possible especially later in the week. The only part of this forecast with above normal confidence is the temperatures as it appears warmer than normal throughout the period, especially regarding overnight lows which could be some 15 to 25 degrees above normal. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... Moisture convergence associated with the weakening front in the area plus nocturnal cooling should result in stratus and fog development tonight. Most of the guidance indicated IFR conditions developing. Followed the HRRR for the timing. Heating and mixing along with the front becoming more diffuse supports improvement late Sunday morning. The NAM and GFS MOS plus most SREF members were in good agreement indicating VFR conditions by afternoon. The pressure gradient will remain weak and expect light wind with westerly more predominate Sunday afternoon. EXTENDED AVIATION OUTLOOK...High low-level moisture associated with the remnants of a front plus an onshore flow combined with noctural cooling indicates widespread stratus and fog may occur during the late night and early morning hours Monday and Tuesday. Widespread restrictions may occur in showers associated with a frontal system Wednesday and Thursday. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$ SYNOPSIS...99 NEAR TERM...99 SHORT TERM...99 LONG TERM...99 AVIATION...99
Area Forecast Discussion
National Weather Service Caribou ME
1012 PM EST Sat Jan 14 2017 .SYNOPSIS... A weak frontal boundary will move across the region tonight with some scattered snow showers across the north. High pressure will build back in across the region through Sunday night. && .NEAR TERM /THROUGH SUNDAY/... 10 PM Update...Some patchy light snow is approaching from the St. lawrence valley and may dust western and northern areas overnight so included low chc pops light snow in those areas tonight. Also, clouds have kept temps up. Cold front will not move through until very late tonight so raised overnight lows a couple degrees. Cold for Sunday but a tad warmer than today. A band of snow showers to affect the Crown of Maine overnight. A weak front is forecast to slide across the region overnight into early Sunday. Model soundings including the NAM/GFS and RAP indicate that there is enough moisture residing from 850-700mbs. Mid level forcing is evident from 12z ua as 700mbs analysis showed a 45-50 kt jetstreak to swings across the region overnight. This could be enough to kick off some snow shower activity or even a brief period of light snow. The best llvl convergence and forcing looks to be right along the Maine-Canadian border. Based on this assessment, decided to increase pops to 40% in the aforementioned area w/20-30% further s into the Caribou-Presque Isle region. Attm, any snow accumulation will be around 0.5(1/2)inch. Clouds will also hold up temps overnight keeping most of the region above zero w/the exception of the far n and w as some site could go below 0F such as low lying sites and by the rivers. As stated above, cold on Sunday but a tad warmer w/sunshine returning. There will be a wnw breeze of 10-15 mph especially across the downeast and eastern areas. This will add a chill to the air. Daytime temps will range from 10-15 across the north and west while central and downeast areas will see low to mid 20s. One interesting thing to note is that the GFS and NAM soundings indicate some instability w/a slight steepening in the llvl lapse rates over the eastern areas such as Washington County. Moisture appears to be limited to the 850mb layer w/alot of dry air above that layer. Therefore, kept out the mention of any snow showers, but winds were increased a bit given the inverted v look to the soundings and 30+ kts above 3k ft. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... High pressure will build to our south Sunday night through Monday. Expect dry weather Sunday night with lows ranging from zero to 10 below across the north and zero to 10 above central and down east. A weak system moving east across Quebec may bring a snow shower or two to far northern areas on Monday, otherwise it will continue dry. Highs on Monday will range from the low to mid 20s across the north/central areas and upper 20s to lower 30s downeast. High pressure will build back in for Monday night and then move east on Tuesday. It will continue dry through Tuesday as low pressure approaches from the west. Lows Monday night will range from the low to mid teens north and mid teens to lower 20s central/downeast. Highs on Tuesday will range from the mid to upper 20s north and low to mid 30s central/downeast. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Increasing clouds can be expected Tuesday night. Precipitation will develop, mainly after midnight, as low pressure begins to track to our northwest. The precipitation Tuesday night will mainly be in the form of snow but possibly a mix of snow or rain across downeast. Precipitation will continue to expand across the region on Wednesday. Precipitation type on Wednesday will be dependent on the development and track of a secondary low that is expected to develop early Wednesday. At this point, will continue with a blended model approach and keep precipitation type primarily snow across the north and rain down east. Precipitation will to taper off to snow showers Wednesday night. Expect a continued chance for snow or rain showers on Thursday. Improving weather conditions can be expected by the second half of the week. Temperatures through the long term period are expected to remain above normal. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... NEAR TERM: VFR w/a brief period of MVFR overnight for the far northern terminals from KPQI to KFVE. VFR for all terminals on Sunday. SHORT TERM: VFR conditions expected Monday through Tuesday. The exception will be in any isld/sct snow showers across the northern terminals KFVE/KCAR on Monday. Widespread IFR is possible after midnight Tuesday and on Wednesday in snow north and snow/rain downeast. Conditions should improve to MVFR/VFR Wednesday nigh and Thursday in lingering snow/rain snow showers. && .MARINE... NEAR TERM: Decided to issue a SCA for the outer zones for later tonight into Sunday as winds are forecast to increase to 15-20 kt w/gusts hitting 25+ kts. The intra-coastal zone looks like it will stay below 20 kts sustained w/a wnw flow. Seas will build slightly but w/the offshore wind, heights will stay below 5 ft. SHORT TERM: Winds/seas will remain below small craft advisory levels Sunday night and then increase to small craft advisory levels Monday. Small craft advisory conditions will then be possible once again on Wednesday depending on the track of secondary low pressure expected to develop. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory from 2 AM to 5 PM EST Sunday for ANZ050- 051. && $$ Near Term...Hewitt/MCB Short Term...Duda Long Term...Duda Aviation...Hewitt/Duda Marine...Hewitt/Duda
Area Forecast Discussion
National Weather Service Hastings NE
954 PM CST Sat Jan 14 2017 .UPDATE... Issued at 931 PM CST Sat Jan 14 2017 Updated the forecast this evening to bring in precipitation earlier in our southeastern CWA. There could be some sleet at onset, but as we warm aloft, the predominant precipitation type tonight should be freezing rain. Also raised low temperature in our north central Kansas counties to about where they are now, which is around 30 degrees. They should be socked in with sky cover and lack of any cold air advection, so a nearly steady temperature for the bulk of the night seems the reasonable way to go, and short-term models such as the HRRR confer with this. As a heads up, I`m leaning toward an earlier start time for our Ice Storm Warning, at least in the southern half of the CWA as the HRRR and RAP indicate the potential for an earlier start time to the freezing rain, and even a little freezing rain can cause big problems. Looking at backing up start times to 09Z (3 am) from roughly I-80 to the Kansas state border. && .SHORT TERM...(This evening through Monday night) Issued at 444 PM CST Sat Jan 14 2017 Apologize for running late with this product this afternoon...needless to say a very challenging forecast trying to slowly-but-surely pin down the details of our upcoming winter storm. For those watching closely, overall the snow/ice totals were not modified much versus the previous overnight forecast package. Will spend more time focusing on headline decisions/general trends than hardcore meteorology in the following few paragraphs. Headline Decisions: The entire CWA was either upgraded to (or continued with) an Ice Storm Warning or Winter Storm Warning. In our 6 KS counties, the Ice Storm Warning begins tonight, but the main impacts will not occur until Sunday into Monday. This KS segment currently runs through Noon Monday in coordination with neighboring KS offices, but would not be surprised if it eventually gets extended at least another 6 hours (something later shifts can monitor). On the Nebraska side, warnings for the southern most few rows start at 6 AM Sunday. Finally, roughly the northern half of the CWA sees Warnings kick in at Noon. All Nebraska counties currently run through midnight Monday night, which corresponds to the very tail end of precipitation potential with this system. Regarding these headlines, a couple of very key points/reminders: 1) The split between the Ice Storm Warning (southeast) and Winter Storm Warning (northwest) was largely based on whether ice accumulation was expected to exceed 0.25" or fall short. In addition, the Winter Storm Warning counties are more favored to see perhaps at least 1-3" of snow as the system departs Monday into Monday night (highest amounts along our far northern/western fringes). 2) HOWEVER, all counties, even the northwest ones not in the official Ice Storm Warning, are expected to see at least 5 to 20 hundredths of ice accumulation on average, which is plenty enough to cause travel issues and at least limited power issues. The bottom line: Just because you are not in an Ice Storm Warning does not mean that you will not see any ice accumulation! It only means that ice amounts will be a bit less, and sleet/snow amounts a bit more. ALL counties in the CWA are subject to plenty of wintry impacts from this system and hence the Warnings. 3) As with all headlines, don`t take "start times" too literally. They are meant to be a general guideline for multiple-county areas, and do not necessarily reflect exactly when precipitation will begin everywhere within the area. Especially northern portions of the CWA may not see much of anything until Sunday night. With these things outlined, will briefly cover the most important weather details of these next few days: The current scene as of late this afternoon: The CWA has enjoyed a dry and modestly warmer day with highs into the 30s all areas. Winds have been extremely light. The main mi- upper level disturbance driving our upcoming storm is still well southwest over the Baja area. This evening/overnight: Although by daybreak the main wave will still be over northern Mexico, large-scale lift mainly in the form of mid-level warm-air advection will get underway, as already evidenced by precipitation increasing in coverage over central/southern KS. For our CWA, while at least spotty light freezing rains/sleet cannot be ruled out roughly as far north as Highway 6 in Neb overnight, the majority of wintry precip should focus south of the state line and thus the Ice Storm Warning starting down there first. Low temps tonight were raised 2-3 degrees and maybe not enough, but mainly low-mid 20s except for teens far north. Sunday daytime: Although it will likely not happen in one big clean "wave", but instead multiple scattered waves of precipitation, freezing rain and sleet will gradually overtake the CWA from south-to-north, as forcing increases ahead of the main vort max which finally reaches southwest TX by day`s end. The majority of precipitation/impacts will likely focus across our southern half through the day though. High temps only a few degrees either side of 30 so plenty cold for ice accrual, especially on elevated/untreated surfaces. Sunday night-Monday daytime: This has been and continues to be the "main show". These 24 hours are when the majority of freezing rain/sleet will occur, with some "plain" snow finally starting to develop as Monday wears on in western counties as colder air moves in. Anybody traveling Monday should expect potentially treacherous conditions, especially in those central/southeast counties that see the highest icing. Primary models are in decent agreement that the main vort max will reach the OK/KS border by daybreak Monday and be centered over the northeast KS/southeast NE area by sunset. As the associated surface low passes to our southeast, light winds will begin to pick up modestly from the north and increase closer to 15 and perhaps 20 MPH. Still though, not overly strong by our standards. For now, we are still expecting some modest warming to slightly above freezing in southern/southeast zones Monday afternoon, which hopefully occurs and allows a switchover to plain rain. If this does not occur, the southern Ice Storm Warning for KS zones may need extended beyond noon. Monday evening/night: Fortunately, by sunset enough cold air will be sweeping in aloft from the west to result in a fairly rapid decrease in freezing rain/sleet potential and more of a transition to snow. We are not expecting major snow amounts, but instead more of a quick-moving but perhaps briefly intense band that lifts across from west-to- east from the late afternoon through evening hours before largely departing by midnight. At least a few inches are expected in our far western/northern counties with perhaps only a few flurries/a light dusting in southern/eastern zones. Sustained winds may try to increase closer to 20 MPH with slightly higher gusts during the night (from the northwest), but unless the associated surface low happens to strengthen much we are not looking at "truly strong" winds the likes of which we often can expect behind these system, and this is good thing for hopefully mitigating infrastructure damage from icing. .LONG TERM...(Tuesday through Saturday) Issued at 444 PM CST Sat Jan 14 2017 For hopefully obvious reasons with all of the weather in the short term...spent very minimal time digging deep into the latter 5 days of the forecast. Briefly summarizing: Little change made from previous forecast. The best news for most folks is that we are looking at a mainly dry forecast along with a fairly decent warm-up to at least slightly above average levels. Temperature summary: Although am admittedly a little skeptical about how quickly we warm up given the expected accumulations of ice/sleet/snow over the next few days, there is plenty of evidence per both the GFS and ECMWF that westerly-to-southerly low level flow will give things a nice boost. High temps Tuesday are aimed into the mid-30s to low-40s range, with highs then aimed well into the 40s and even a few 50s Wednesday-Friday before easing back a few degrees on Saturday but still widespread 40s. Overnight lows generally 20s to around 30s. Precipitation summary: There are some very low chances for rain and/or snow in the Friday-Saturday time frame as both the ECMWF/GFS swing the next primary mid level disturbance in from the southwest. Although the details are extremely murky at this time, for now these look like pretty minor/low-impact precip chances, with the temperature profile likely less-conducive to mixed precip types than with the impending short-term storm. Possible hazards: None foreseen from precipitation at this time. In other departments, although ice jam issues are extremely hard to foresee, the general pattern of widespread precipitation potentially in excess of one-half inch in some areas (quite a bit for January), followed by a decent warm-up could possibly give us a shot at some ice jam issues in our typically-favored spots along the Platte/Loup Rivers as the week goes. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday evening) Issued at 545 PM CST Sat Jan 14 2017 Main issue will be the onset of frozen precipitation, which could be a mix of sleet and freezing rain, with freezing rain being the primary focus as an Ice Storm Warning is in effect for KGRI beginning 18Z Sunday and Winter Storm Warning in effect at 18Z for KEAR, where there is still ice expected, but should stay under 1/4 inch ice accumulation. Ceiling will gradually lower through Sunday afternoon. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Ice Storm Warning from 6 AM Sunday to midnight CST Monday night for NEZ074>077-083>087. Winter Storm Warning from 6 AM Sunday to midnight CST Monday night for NEZ072-073-082. Winter Storm Warning from noon Sunday to midnight CST Monday night for NEZ039-040-046-047-060-061. Ice Storm Warning from noon Sunday to midnight CST Monday night for NEZ041-048-049-062>064. KS...Ice Storm Warning until noon CST Monday for KSZ005>007-017>019. && $$ UPDATE...Heinlein SHORT TERM...Pfannkuch LONG TERM...Pfannkuch AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Grand Junction CO
755 PM MST Sat Jan 14 2017 .UPDATE... Issued at 755 PM MST Sat Jan 14 2017 Visibilities are beginning to decrease across the same northern valleys that have seen dense fog over the past several nights as well as portions of the Central Gunnison River Basin. Areas of dense fog will persist through at least 10 AM tomorrow morning. Therefore, went ahead and hoisted a Dense Fog Advisory for these areas and updated the grids accordingly. Visibilities are also decreasing in and around Telluride, but will hold off on issuing any highlights at this time and continue to monitor the situation. UPDATE Issued at 454 PM MST Sat Jan 14 2017 All highlights will be allowed to expire at 5 pm this evening with diminishing returns on radar fitting trends in HiRes RAP and HRRR models. Still expect snow showers through the night, but significant accumulations no longer expected in highlighted areas. Fog has also lifted some across northwest Colorado with visibilities generally above 3 miles, so the Dense Fog Advisory will also be allowed to expire at 5 pm. Little more separation between the T/Td at the moment, although another round of dense fog is not out of the question later tonight as temperatures start to cool back down. && .SHORT TERM...(Tonight through Sunday night) Issued at 338 PM MST Sat Jan 14 2017 The upper level low pressure system is currently situated just off the Baja and making its way inland. During the late morning and early afternoon hours, an enhanced band of precipitation moved across southwest Colorado and southeast Utah producing heavy snow in the mountains with rates of up to 3 inches per hour over the San Juans, where winter highlites remain in place through 5 pm today. The lower valleys south of I-70 were primarily affected and precip type stayed rain for the most part with a few spots mixing in briefly with snow. Current radar and satellite trends show that this band has since weakened and is pretty much losing its characteristics as it is moving into an area of more stable air north of I-70. This area north of I-70 has been seeing areas of fog, some of which has been dense throughout the morning and early afternoon. Visibility has since improved as of 3 pm but current guidance shows fog setting back in mainly across the northern valleys overnight through Sunday morning. Later shifts will have to look into the possibility of dense fog occurrence once again given the moist low levels. Precipitation intensity has also lessened this afternoon as well and expect a general downward trend in shower activity this evening. Some convection and thunderstorms are rotating around the low across Arizona and southwest New Mexico, but do not expect this thunderstorm activity to sustain itself by the time it makes its way northward. Models appear to indicate an overall downturn in precipitation this evening into the overnight hours for most areas. The exception to this is a batch of showers left over from convective activity passing through Arizona and New Mexico that will move through southeast Utah. As the upper low shifts further east across northern Mexico overnight into Sunday morning, some more moisture looks to rotate up through southwest Colorado towards Sunday morning. The H7 flow will shift around to the east which tends to favor the eastern slopes of the eastern San Juans. It appears this wave will clip the eastern portion of the western San Juan mountains mainly up through Wolf Creek Pass and maybe Pagosa Springs. It will be brief with weak forcing so maybe a couple inches of snow for the western San Juans. A secondary shortwave will move down the west coast on the back side of this low pressure trough with some jet energy, helping to quickly push this low further eastward as it lifts across Texas. This low is a bit further south and east than previous models indicated which does not favor our CWA for significant precipitation. Trended back the pops by lowering them the further west and north you go during the day on Sunday. Thinking that some light snowfall will continue but additional accumulations appear minimal and gradual throughout the day with no significant impacts. As said previously, the eastern San Juans are favored in this upslope type of flow with the western San Juans being quite shadowed. The orographic lift is not overly strong enough to allow much significant snow to spill over into our western San Juan mountains. Northerly flow takes hold Sunday evening into Monday morning, bringing much drier air into the region and putting an end to most precipitation. Based on the above reasons, elected to let the current winter highlites expire at 5 pm and will not continue or issue any for the upcoming wraparound precip on Sunday. Snow will continue in some areas, but accumulations are expected to be light. .LONG TERM...(Monday through Saturday) Issued at 338 PM MST Sat Jan 14 2017 Some light snow may linger over the San Juans Monday morning favoring the north facing slopes but overall precipitation will be coming to an end across the area as drier air advects in under northerly flow. Some cooler air will be in place as well on Monday following the final passage of this lingering storm system. High pressure will build across the west and lay across the region from west to east early this coming week, providing dry conditions for most the region through Wednesday. A weak shortwave looks to clip the northwest Colorado mountains on Tuesday with mainly an increase in clouds and the slightest chance of light snow. Temperatures should moderate by Tuesday into Wednesday with values closer to normal if not slightly above as warm air advection takes place ahead of the next series of storms set to impact the region later this coming week. So before this occurs, it looks like a dry and quiet period will be in store from Monday through Wednesday. Clouds will increase on Wednesday as the flow shifts to the west ahead of the next series of Pacific storms making landfall onto the Pacific Northwest and northern California coast. The first in a series of storms moves across the region Thursday morning through Friday morning with another one on its heels Friday afternoon through the weekend. This second one looks stronger as it deepens and forms a closed low on the lee side of the Rockies. Details are a little fuzzy since this is a ways out and models have a tendency to change, but overall it looks like an active and unsettled pattern takes shape Thursday through the weekend with more snow in the mountains and a rain/snow mix in the valleys initially on Thursday, possibly changing to all snow by Friday as H7 temps lower to around -8C by Friday morning and range from -10C to -12C by the weekend. Moisture with this next series of storms is modest but not overly as impressive as the previous atmospheric river event that kept the weather active the first two weeks of January. Specific humidity values with this next series of storms range from 2.5 to 3.5 g/kg. In comparison, the two week long atmospheric river event averaged about double this amount. Stay tuned! && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 454 PM MST Sat Jan 14 2017 A Pacific storm passing to the south will continue to generate precipitation south of the I-70 corridor through Sunday morning. This will result in prolonged periods where CIGS are below ILS breakpoints for all sites along and south of Interstate 70. In addition, areas of MVFR and IFR CIGS and VSBYS will be common with showers and fog moving through the region. Fog appears most likely at KVEL, KCAG, KHDN and KSBS tonight with patchy fog in the vicinity of KGJT, KRIL, KEGE and KMTJ. Conditions improve from northwest to southeast after 18Z/SUN. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...Dense Fog Advisory until 10 AM MST Sunday for COZ001-002-005-011. UT...Dense Fog Advisory until 10 AM MST Sunday for UTZ024. && $$ UPDATE...MMS SHORT TERM...MDA LONG TERM...MDA AVIATION...JDC
Area Forecast Discussion
National Weather Service Lincoln IL
904 PM CST Sat Jan 14 2017 .UPDATE... Issued at 850 PM CST Sat Jan 14 2017 No significant changes being made this evening in the short term forecast or any of the headlines that are currently out. Weak high pressure was centered over central Illinois this evening with quite a bit of cloud cover across the forecast area. Only exception was over our northern counties where skies have cleared with a slow southward shift in the clearing trend noted in the satellite data and surface observations over the past couple of hours. Further south, we still have a solid stratus deck south of I-72 with the possibility for some drizzle or freezing drizzle coming out of the lower clouds at times overnight. However, have not received any reports of that this evening but will keep an eye out for that. The next wave of freezing rain with even some isolated thunderstorms was located over southwest Missouri this evening. Latest RAP and HRRR models indicate the bulk of that precip will affect parts of southwest through southern Illinois by morning. Will see some light ice accumulations (less than a tenth of an inch) from that, but like today, afternoon temperatures will be at or a couple of degrees above freezing. Further north towards the I-74 corridor, we will have a tough time getting much precipitation that far north until late in the day or at night. For the most part, the forecast has a good handle on the overnight trends but will make some minor adjustments in the timing of the precip across our far west tomorrow morning. We should have the updated zones out by 915 pm. && .SHORT TERM...(This evening through Sunday) ISSUED AT 300 PM CST Sat Jan 14 2017 Batch of light freezing rain exited east of east central IL early this afternoon with a weak short wave. Though low stratus clouds with bases of 500-1500 ft and a light fog from IL river southeast could have patchy freezing drizzle with surface temps of 28-32F over central IL at mid afternoon. Just patchy drizzle over southeast IL along and southeast of I-70 where temperatures were 34-38F. 1035 mb canadian high pressure was over eastern SD and ridging into the Midwest and light nw winds trying to bring in drier air. Dewpoints range from upper teens to mid 20s nw of the IL river, to the mid 30s in southeast IL. Added patchy fog to southeast IL tonight and into central IL as well overnight as temps cool toward dewpoints and winds remain light with abundant low level moisture from recent precipitation. The second round of wintry precipitation will arrive across SW IL including far SW CWA sw of Springfield and Lawrenceville late tonight, and over rest of the CWA during the day Sunday, likely not reaching the northern CWA until during Sunday afternoon. Cooler lows overnight range from lower 20s nw of IL river, to the upper 20s to near 30F in southeast IL. The latest forecast models continue slower spreading qpf into central IL and cooler temperature profile trends. 850 mb temps are forecast to be zero to plus 2C over northeast CWA on Sunday and may see more of a mix of light snow and sleet especially from I-74 ne before changing to light freezing rain after sunset Sunday. Surface temperatures rise to similar readings as today, with lower 30s over IL river valley, and upper 30s in southeast IL where mix pcpn Sunday morning turns to all rain Sunday afternoon. The freezing rain advisory for Fulton, Tazewell and McLean counties will be cancelled as well as for Clark, Jasper, Richland, Lawrence and Crawford in southeast IL where temps are above freezing thru this evening. The Winter Storm Watch for northern CWA will be converted to a Winter Weather Advisory Sunday night and Monday morning and include areas from Fulton, Tazewell and McLean counties north. Will continue the Freezing Rain Advisory for rest of CWA through noon Sunday for light ice accumulations up to a tenth of an inch or less, highest amounts in sw CWA where highest pops are by Sunday morning. .LONG TERM...(Sunday night through Saturday) ISSUED AT 300 PM CST Sat Jan 14 2017 Precipitation expected to push northward Sunday night as increasing southerly flow develops ahead of a low approaching via the southern Plains, currently moving into northern Mexico. Southeasterly winds at the surface will allow temperatures to start an increasing trend, but still expecting freezing temperatures for at least portions of the night from I-70 northward causing continued potential for freezing rain as well as a mix of sleet and snow. Temperatures will rise above freezing by about mid morning in the vicinity of I-74 then temperatures should remain above freezing for at least the next day...until Tuesday night. Planning on issuing a winter weather advisory from Sunday evening through Monday morning from Fulton to Mclean county northward for the mix of ice, sleet, and snow. With the strong low approaching the northwest corner of Illinois by Monday night...increased chances for rain will also develop along with the increased temperatures...with amounts around 1/2 to 3/4 inch likely from Monday morning to noon Tuesday. MUCAPE values in the 200 J/kg range associated with the warm sector southeast of the low imply thunderstorms possible so have included slight chance of thunderstorms starting Monday afternoon southwest of Springfield, then across central IL Monday evening...then shrinking down to I-70 southward Monday night. Only a brief pocket of cooler air will affect central IL Tuesday night through Wednesday night with lows in the upper 20s to mid 30s and highs in the 40s followed by warm advection ahead of the next low pressure system. Highs thursday through Saturday should increase into the 50s. After dry weather midweek...there is a chance for rain by Friday, although model inconsistencies this far out imply low predictability. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 510 PM CST Sat Jan 14 2017 Drier air continues to slowly work its way south into our area in the wake of the weather system that brought the freezing rain to the forecast area this morning and early this afternoon. As a result, we have seen cigs improve to VFR at PIA with mainly MVFR cigs at the other TAF sites. RAP forecast soundings suggest improving conditions from north to south late this evening where we may see a temporary VFR cig further south at SPI, DEC, and CMI. Low level moisture will remain in place so if we do clear out for a time later tonight, we may see vsbys come down to MVFR in fog during the early morning hours. The next weather system will start to approach SPI by 11z-14z with another round of -FZRA possible during the morning hours along with cigs lowering to IFR. Winds are going to remain light through the forecast period, mainly from the north tonight around 5 kts and winds will shift into an easterly direction on Sunday with speeds again around 5 kts. && .ILX WATCHES/WARNINGS/ADVISORIES... Freezing Rain Advisory until noon CST Sunday for ILZ040>057-061- 062-066-071. Winter Weather Advisory from 6 PM Sunday to noon CST Monday for ILZ027>031-036>038. && $$ UPDATE...Smith SHORT TERM...07 LONG TERM...37 AVIATION...Smith
Area Forecast Discussion
National Weather Service Jackson MS
936 PM CST Sat Jan 14 2017 .UPDATE... Updated for evening discussion. && .DISCUSSION... A small region of patchy fog was added to the Delta as METAR observations continue to show low visibility. Otherwise no other modifications have been made to the latest forecast update./12/ Prior discussion below: and little to no precipitation has allowed dewpoints this afternoon to mix out 5 to 10 degrees lower than this time yesterday. While there was some dense fog this morning over the south, visible satellite imagery this morning showed that it was mainly confined to river channels and the usual fog problem spots. It seems as though the HRRR is aware of this as it is showing the only area for possible dense fog tonight along and just behind the quasi-stationary frontal boundary skirting the northern portions of the forecast areas. This makes sense as latest surface data is indicating the best moisture pooling near the boundary. Still, believe most areas will see some fog tonight, but it will be the northern portions and the usual fog problem spots that see anything potentially dense. Mid level ridging will continue the string of abnormally warm days for Sunday as highs reach into the mid and upper 70s. The exception will be over the far northwest where cooler air and cloud cover behind the boundary will keep readings in the mid 60s./26/ Sunday Night through Friday: For Sunday night we will start with another late night with some patchy fog across the region. Mild conditions will continue through the period with better chances of rain as we move through the work week. A low pressure system coming out of the Southern Plains will drag a surface low with it to the Great Lakes Region. This will bring a front to our western area by early Tuesday. The front will push across the region on Tuesday and will settle across our southern counties on Tuesday evening. After that it seems to become quasi-stationary around our southern counties for Wednesday and Thursday. Models have different opinions on when it pushes back to the north on late Thursday into Friday. This will occur as our focus shifts to the Southern Plains where a storm system will be developing. Not to mention the different timing of the shortwaves and their amplitude coming across the region in this split flow pattern. However pwats will build from 1.5 to 1.7 inches with the frontal boundary around, which will give some opportunities of some locally heavy rainfall. However with such diversity of model solutions confidence is rather low. One thing is for certain we will get rounds of showers and some thunderstorms during most of the period with the passing disturbances. This was shown by both the European and GFS ensembles. Do not see any organized severe potential for the period. Looking ahead the Canadian,GFS, and Euro shows a strong system coming out the Southern Plains which may affect the region for next weekend. The models have a different scenario but it bears watching. /17/ && .AVIATION... 00Z TAF discussion: VFR conditions were observed at all TAF sites at 00Z and VFR conds will prevail through 06Z. After 06Z areas of fog and low clouds will begin developing with flight categories falling through MVFR to IFR by 15/09Z at GLH/GTR and HBG. Elsewhere, MVFR visibilities can be expected by morning, but somewhat drier air in the lower levels should prevent the fog from becoming widespread and dense as last night. /26/22/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 52 76 57 76 / 2 4 9 21 Meridian 50 76 56 76 / 3 4 6 18 Vicksburg 51 73 58 75 / 3 5 12 26 Hattiesburg 51 77 58 77 / 3 5 7 17 Natchez 53 75 59 76 / 3 7 14 25 Greenville 50 70 55 71 / 4 7 12 43 Greenwood 51 73 57 74 / 4 6 9 30 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ 12
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
834 PM CST Sat Jan 14 2017 .UPDATE... Issued at 819 PM CST Sat Jan 14 2017 Next batch of freezing rain moving through southwest MO this evening. Even a few lightning strikes in this area of precipitation. Looking at the latest radar loops and HRRR model runs it appears that this precipitation will move into parts of central and southeast MO by late evening, then impact areas along and south of I-70 overnight. Until this area of mainly freezing rain moves in later tonight there will be patchy fog and freezing drizzle. GKS && .SYNOPSIS... Issued at 254 PM CST Sat Jan 14 2017 No changes to current headlines with ice storm warnings continuing into Sunday. Next main wave of precipitation/freezing rain spreads into the area after midnight and impacts the region through Sunday morning, diminishing Sunday afternoon. Additional ice accumulations generally 0.10-.20 with localized area near 0.25 inches. && .SHORT TERM... (Through Late Sunday Afternoon) Issued at 254 PM CST Sat Jan 14 2017 Focus thru this period continues to be the impending icing event. Ongoing rain will continue across extreme srn portions of the CWA thru this afternoon. Can not rule out a passing shower this evening across this region, but believe much of the evening will remain dry. A s/w currently over nrn TX/wrn OK region is progd to lift enewd today and tonight. This is expected to spread precip into the area, mainly after Midnight tonight. However, mdls depict enuf forcing to indicate some light precip ahead of the s/w. After the first wave of precip pushes thru the area Sun morning, precip shud refocus across nrn and into central portions of the CWA. As for temps, expect temps to drop a degree or two across the region after sunset. Temps shud remain fairly steady overnight and may actually rise a degree or so with onset of precip. Temps shud slowly rise late Sun morning into the afternoon. Expect most of the CWA to be aoa the freezing mark by 21z Sun, except far northern MO and west central IL. Given the temps expected thru Sun, may see an additional tenth or two of ice accumulation at any given spot thru the period. Tilly .LONG TERM... (Sunday Night through Next Saturday) Issued at 254 PM CST Sat Jan 14 2017 The main wave of significant precipitation from Sunday should have shifted north of the CWA, or be close to exiting north of the CWA at 00Z Monday. In the wake of this wave, an additional precipitation will be spotty or scattered on Sunday night with the highest probability across northern MO into central IL. Surface temperatures will generally be in the 31-33F range across northeast MO/west central IL during the evening. Overnight however, temps should uniformly warm above freezing as the surface high pressure dome continues to retreat eastward from the Great Lakes region, surface winds slowly veer and increase, and as upper flow exhibits prounouced backing. The models have come into better agreement in the Monday/Tuesday time frame, then diverge some thereafter. The general consensus is the primary upper low will lift northeastward through the central Plains on Monday and into the Upper MS Valley on Monday night. Correspondingly, the accompanying surface low will track into northwest MO by 00Z Tuesday and into the western Great Lakes region by Tuesday morning. Deepening and strengthening south/southwesterly flow aloft and strengthening/veering surface winds associated with the movement of the aforementioned upper level and surface systems will transport unseasonably mild air across the CWA on Monday/Monday evening ahead of the surface low and advancing cold front. This will not only result in well above average temps and melting to any residual ice, but will also help promote enough instability to mention the possibility of embedded thunderstorms as a band of rain/showers translates across the area Monday/Monday night. The cold front should completely exit east of the area by midday Tuesday with weak CAA in its wake and potentially some "wrap-around" precipitation in northeast MO and west central IL. The air in the wake of this front however is not all that cold for January. Temperatures moderate quickly by Wednesday as a WAA regime becomes re-established and persists with varying degrees through the remainder of the week. Temperatures looks to be well above average Wed-Fri. Glass && .AVIATION... (For the 00z TAFs through 00z Sunday Evening) Issued at 547 PM CST Sat Jan 14 2017 IFR or near IFR stratus clouds along with fog will continue through the period. Another round of freezing rain will move into the taf sites late tonight and continue Sunday morning. Temperatures will warm up enough in COU and the St Louis metro area to change the freezing rain to rain early Sunday afternoon. Light northerly surface wind will veer around to an easterly direction Sunday afternoon as the surface ridge over the northern Plains moves eastward into the Ohio valley region. SPECIFICS FOR KSTL: IFR or near IFR stratus clouds along with fog will continue through the period. Another round of freezing rain will move into the STL area late tonight and continue Sunday morning. Temperatures will warm up enough to change the freezing rain to rain early Sunday afternoon. The rain should end by Sunday evening. Light northerly surface wind will veer around to an easterly direction Sunday afternoon as the surface ridge over the northern Plains moves eastward into the Ohio valley region. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...Ice Storm Warning until 6 AM CST Sunday for Crawford MO-Iron MO- Madison MO-Reynolds MO-Saint Francois MO-Sainte Genevieve MO-Washington MO. Ice Storm Warning until 3 PM CST Sunday for Audrain MO-Lincoln MO-Monroe MO-Pike MO-Ralls MO. Ice Storm Warning until noon CST Sunday for Boone MO-Callaway MO- Cole MO-Franklin MO-Gasconade MO-Jefferson MO-Moniteau MO- Montgomery MO-Osage MO-Saint Charles MO-Saint Louis City MO- Saint Louis MO-Warren MO. Ice Storm Warning until 6 PM CST Sunday for Knox MO-Lewis MO- Marion MO-Shelby MO. IL...Ice Storm Warning until 6 AM CST Sunday for Randolph IL. Ice Storm Warning until 3 PM CST Sunday for Calhoun IL-Greene IL- Jersey IL-Macoupin IL-Montgomery IL-Pike IL. Ice Storm Warning until noon CST Sunday for Bond IL-Clinton IL- Fayette IL-Madison IL-Marion IL-Monroe IL-Saint Clair IL- Washington IL. Ice Storm Warning until 6 PM CST Sunday for Adams IL-Brown IL. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Paducah KY
1000 PM CST Sat Jan 14 2017 .UPDATE... Issued at 1000 PM CST Sat Jan 14 2017 As expected measurable rainfall has been very scarce this evening, and will continue to be so into the overnight hours. An area of rain over southwest Missouri is moving northeast and should not reach our area until 09Z or so. Of course, the latest HRRR runs are non-committal on whether or not it will reach our area. Held PoPs at low chance levels until very late tonight before ramping up to 50-60% in the northwest. Of course, this is where temperatures will be right at the freezing mark, so will have a mention of freezing rain. With temperatures expected right near 32F, figure any icing will be limited to elevated objects. With little, if any, ice from yesterday left in these areas, the impact should be nil. Have addressed this in the HWO and do not plan to issue any extra products for this event. There have been some very light echoes on area radars this evening, and some lowered visibilities in METARs, indicative of some light drizzle. With the rain in the forecast, just settled for mentioning areas of fog, which is what we have seen here at the office recently. UPDATE Issued at 610 PM CST Sat Jan 14 2017 Updated aviation discussion. && .SHORT TERM...(Tonight through Monday night) Issued at 225 PM CST Sat Jan 14 2017 Have allowed winter/fog headlines to expire this afternoon as vsbys have improved and surface temperatures have crept just above the freezing mark over nw counties with precip shifting south toward the OH River. Could be another batch or two of very light rain or drizzle overnight tonight at many locations as the lower atmosphere remains quite saturated. Not much forcing to work with though, so any QPF should be quite light. Temperatures not expected to fall off much during the night, but it would not take much of a drop to get our northern/western counties of srn IL/se MO back to near or just below freezing. Will need to monitor to see how precip/temp trends go this evening up in those locations for possible quick advisory for some freezing drizzle/light freezing rain possibilities. Weak mid level ridging on Sunday will also serve to keep any significant amounts of precip out of the region, though will need to leave some chance for a bit of very light precip, especially along/north of the I-64 corridor. Again, would not be surprised to see a touch of freezing precip in that corridor early in the day, but will hold off on headlines at this time and handle with HWO/possibly an SPS. Next high chance of rain/isolated thunder looks to hold off until later Mon/Monday night time frame as the next surface front and associated H50 short wave approach from the west. Not too excited at this time on strong/severe threat given overall lack of instability. More likely just a few isolated rumbles of thunder here and there. Could be some decent widespread rain amounts up over 1/2 inch tho. .LONG TERM...(Tuesday through Saturday) Issued at 225 PM CST Sat Jan 14 2017 The northern hemispheric pattern has the center point of the wave pattern shifted toward the Arctic circle northwest of Alaska at the start of the extended forecast period, with the most dominant meridional wave extending from the pole to east of Greenland and a low amplitude, split trough over the Northern Pacific. The evolution of the primary stable five wave pattern (per the ECMWF and GFS guidance) into a 3-4 unstable wave pattern, suggest a more dynamic and chaotic flow over the U.S. during the extended period. However, the dominance of the mean trough east of Greenland/Northern Atlantic, may mean greater heights upstream over the eastern U.S., pushing systems to the west of the WFO PAH forecast area further to the west and north. Although the GFS and ECMWF similarly handle the ejection of the Baja California low into the western Great Lakes through Tuesday, the similarity begins to wane with time, especially late in the week. The 12z Saturday ECMWF is a little warmer aloft, but cooler at the surface than the 12z Saturday GFS. A blend of ECMWF/GFS seems to be a more realistic solution. For the WFO PAH forecast area, this would be mean that the weather system on Tuesday should exit a little quicker, with the system moving from the southwest Thursday into Friday should be shifted more to the east with time in a more progressive flow. Blended max/min temperatures upward slightly from the cooler ECMWF values, but still lower than the GFS. In addition, kept PoPs in place closer to the slightly faster and more eastern ECMWF than the warmer and more unstable GFS. There is lesser forecaster confidence in the late week solution (40-50%) than the Tuesday weather system (60-70%). Otherwise, no significant changes in the other sensible weather elements through the forecast period. && .AVIATION... Issued at 610 PM CST Sat Jan 14 2017 Weather conditions are expected once again to deteriorate overnight with the diurnal cooling of the lower trop. Meanwhile, a wedge of cool air near the surface will pivot eastward through the region, causing some veering of the surface winds. IFR cigs are expected soon, if not there already, and should go LIFR after midnight. Vsbys should eventually go IFR sometime this evening in drizzle and fog, with a chance of LIFR levels (not in TAFs currently). By mid morning Sun, heights aloft will begin to rise, resulting in improving conditions, albeit with rain showers, from southwest to northeast. However, IFR cigs will probably remain through the end of the 00Z TAF period. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...DRS SHORT TERM...GM LONG TERM...Smith AVIATION...DB
Area Forecast Discussion
National Weather Service Blacksburg VA
641 PM EST Sat Jan 14 2017 .SYNOPSIS... A weak cold front has drifted south of the region and will remain south of the area tonight into Sunday and will drift back north of the area Monday. Meanwhile, a series of disturbances aloft will track over the region keeping clouds and periods of precipitation across the region for several days. Finally, a stronger cold front is slated to move through the region by the middle of next week. && .NEAR TERM /THROUGH SUNDAY/... As of 300 PM EST Saturday... Arctic high pressure to our north will slide east tonight into Sunday. The high center pushed colder air pushing into our region. The frontal boundary has moved south of us and was located across Georgia and South Carolina this afternoon. A wave of low pressure will ride east tonight into Sunday. Regional WSR-88d images showed an area of rain off to our west mainly north of the Ohio River. This feature will rotate east tonight into Sunday. Utilized a blend of the HRRR and Hiresw arw-east for this afternoon into tonight because they capture this precipitation best. Then, blended in the nam for pops overnight into Sunday. In general, the Models seem to focus more activity west in the Tennessee valley overnight/early Sunday. At any rate, there will likely be patchy of fog and drizzle when it is not raining with low level moisture. With a non diurnal temperature curve, low temperatures range from the lower 30s in the northwest Greenbrier county to the mid 50s in the southwest mountains. With temperatures close to freezing in western Greenbrier county, there is a slight chance for freezing rain late tonight into early Sunday morning. The low level wedge across the region Sunday morning will weaken as the flow turns more northwest behind a weak exiting wave offshore. This may result in some drying especially across central and eastern portions of the forecast area Sunday before another transient but weaker surface high starts to build in from the north. Another Mid level shortwave will rotate east returning precipitation to the west and spreadings east by late Sunday. High temperatures Sunday will vary from around 40 degrees in the northern mountains to the lower to mid 50s along the southern Blue Ridge mountains. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... As of 330 PM EST Saturday... Split flow pattern over North America will persist through Tuesday. This will keep our forecast area pinned between the colder northern stream westerlies to our north and subtropical warmth along the Gulf Coast. Closed southern stream low over the southwestern CONUS will be the focus for pieces of short wave energy which will eject east, resulting in period lift along a wavy surface front which bisects the Mid-Atlantic from west to east, dividing the colder air associated with the northern stream from the warmer subtropical air to our south. Result will be abundant cloud cover with the potential for rain and/or drizzle. Highest potential for rain during this time frame will be Sunday night and again Tuesday night, with widely scattered showers in between. Sunday night, models indicate about a 6-8 hour period of isentropic lift promoting 60-80 percent chance of rain, the highest pops vicinity of the blue ridge where lift will be maximized from the easterly low level wind field. Can`t rule out an hour or two of freezing rain/drizzle early Monday morning at the highest elevations along the Blue Ridge (Peaks of Otter and points north along the Blue Ridge Parkway) where temperatures will test 32 degrees. Elsewhere, just looking at a cold rain. Surface front will get a nudged north Monday into Tuesday, so temperature trend Monday into Tuesday should be up, with steady or increasing temperatures, from 40s Monday, steady or rising Monday night (40s/50s), testing 60 on Tuesday. Closed low over the southwest is expected to eject northeast into the upper Mid-West by Wednesday. This will send a surface front east bound, this feature approaching our area Tuesday night. Convergence along the front will likely result in another period of rain or rain showers, beginning as early as Tuesday evening in the mountains, then spreading east across the forecast Tuesday night. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 345 PM EST Saturday... Surface front is forecast to cross the forecast area early Wednesday. Attm, models do not indicate much in the way of cool air behind the front, a few degrees drop at 850 mb, so once we dry out behind this feature Wednesday, the afternoon should be fairly nice with Temperatures once again testing 60. Beyond Wednesday, the weather pattern still looks mild. A new cutoff low is forecast to take up residence within the southern stream over the southwestern CONUS with ridging over the southeast States and Gulf Coast. There are some model differences with respect to how far east the southern stream trough will progress next weekend. This results in timing differences with respect to precipitation. Per the mild pattern, there should not be any P-type issues for our forecast area with any precipitation falling in the form of rain. Forecast high temperatures will run about 10- 20 degrees above normal Wednesday through Saturday. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... As of 636 PM EST Saturday... Overall poor flying conditions will continue tonight as a wedge of high pressure locks in along and east of the mountains. Low clouds with patchy light rain and drizzle will combine to produce IFR/LIFR cigs and MVFR/IFR vsbys in the mountains and MVFR out east where cloud bases should remain higher and rainfall less. Pilots should prepare for Mountain Obscurations into Sunday. Medium to low confidence with cigs and vsbys through Sunday given varying conditions in and out of the wedge through the weekend. Spotty nature of fog and drizzle is also problematic. Higher confidences that east to southeast winds will prevail on Sunday. Extended Aviation Discussion... A baroclinic zone will remain anchored across the region sandwiched between a strong upper ridge over the southeast states and an active jet stream from the southwest U.S. into the northeast U.S. Thus, an unsettled, wet weather pattern is expected to remain in place Monday into Tuesday. The frontal boundary may lift north enough by Monday night for a brief period of mainly VFR, but a stronger front will arrive By Tuesday with more showers including widespread sub-VFR. Generally looking at MVFR much of the period, although periods of VFR as well as IFR- LIFR can be expected at times. Passing cold front from later Tuesday should clear the region on Wednesday allowing for a return to VFR across the region for midweek. Moisture may return from the southwest Thursday afternoon into Thursday night. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...KK NEAR TERM...KK SHORT TERM...PM LONG TERM...PM AVIATION...JH/KK/RCS
Area Forecast Discussion
National Weather Service Topeka KS
940 PM CST Sat Jan 14 2017 .UPDATE... Issued at 940 PM CST Sat Jan 14 2017 The radar at 02Z showed 925MB winds were still from the north indicating there may be some low level dry air advection still occurring. With the 00Z NAM and 18Z GFS showing little in the way of strong synoptic forcing until late in the day Sunday, have been looking at isentropic surfaces for signs of lift and forcing for precip. However profiler data shows the stronger more southerly winds remain well to the south over TX while 850 winds over eastern KS are still veered to the southwest. This doesn`t seem very favorable for moisture advection into northeast KS. Because of this have trended POPs down 10 to 20 percent and precip overnight may be more the isolated/scattered nature than a widespread shield of precip. Will continue to monitor trends and adjust. UPDATE Issued at 537 PM CST Sat Jan 14 2017 Light north winds at the surface suggest there may still be some weak dry air advection going on and the light freezing rain appears to be fighting this dry air based on recent radar trends. 00Z sounding that just went up shows this dry layer to be about 2500 feet deep. because of this have delayed the onset of precip a few hours. Latest RAP shows low level isentropic lift increasing on the 295K surface around 03Z and this is when the freezing precip is anticipated to spread further north into the forecast area. && .SHORT TERM...(This evening through Monday) Issued at 331 PM CST Sat Jan 14 2017 Current satellite shows holes in the cloud cover that have caused temperatures to warm into the mid 30s. Slight isentropic downglide has contributed to this drying, but has kept the dew points much lower. The only exception would be far eastern KS where the moisture is deeper and closer to the ground. An area of showers and rain is moving towards the area from the southwest. It should arrive in the forecast area late this afternoon and evening. Wet bulbing due to evaporation should cool the temperatures into the 20s and lower 30s therefore resulting in freezing rain once the column saturates. Some of the high res models are struggling with this batch of precipitation by either eroding it away or tracking it south of the forecast area. They are also underestimating the precipitation coverage. There is a chance that once freezing rain begins it might not stick to objects or pavement until conditions cool this evening and wet bulbing is finished. Also, temperatures are forecasted to cool a few degrees in general due to the loss of daytime heating. Most of the area stays below freezing before sunrise tomorrow morning. Larger scale models bring a continuous stream of precipitation in the form of freezing rain tonight for areas mainly along and south of I-70. This is when these areas could receive significant icing. While more isolated to scattered freezing rain showers are possible north of I-70. By late tomorrow morning the freezing rain may still be ongoing for most of the area. Temperatures will begin to warm to near freezing starting in east central KS, and that trend will gradually move northward into the afternoon. This will be the tricky part of the forecast since a few degrees separates freezing rain vs rain. The models are now hinting that the majority of the precipitation tomorrow late morning and onward will fall along and north of I-70. This is when these areas could receive significant icing. Light precipitation is still possible elsewhere during this time frame. There could be a lull Sunday evening and overnight before the main upper level low pressure lifts out over the plains. By this time a majority of the area may be above freezing. Although there is a chance that portions of north central KS could stay in the freezing rain. This would cause higher amounts in these areas by Monday morning. Generally ice amounts will be between 0.25" and 0.75" with locally higher amounts possible. A closer look of at the 12z GFS ensembles show that the operational GFS has some of the warmest temperatures by a few degrees out of all of the members. Also, the 18Z NAM keeps wet bulb temperatures below freezing for a majority of the area through tomorrow evening. The operational GFS has the some of the lowest total QPF compared to all of the ensemble members for northeast KS through tomorrow night. The orientation of the 850 mb low level jet would suggest strong moisture convergence to support this widespread precipitation through tomorrow. Neutral advection at the surface under light northeast winds would suggest steady temperatures. Not sure how much mixing of the warm nose down to the surface will actually take place. All of these factors would lead me to believe that widespread significant ice accumulations as still possible. .LONG TERM...(Monday night through Saturday) Issued at 331 PM CST Sat Jan 14 2017 On Monday night the upper level low will move overhead and off to the northeast. There is some potential for moisture to wrap around the low, interact with an incoming weak vort max from the northwest, and possibly support a last shot of a light wintery mix of precipitation. Chances for anything to accumulate are low and additional impacts are unlikely but will continue to monitor this period in case deep moisture and lift are a bit stronger or if the upper low moves out a bit slower. Temperatures warm markedly for the rest of the forecast period. Several negatively tilted upper level short wave troughs will cross the Plains between Thursday and next weekend, but moisture return will be limited prior to the weekend. For now have only very small pops for the system on Friday, which looks to have warm temperatures to support rain if precip develops. The late weekend storm system looks potentially more interesting but the current storm track looks to have the local area on the warm side of things. && .AVIATION...(For the 00Z TAFS through 00Z Monday) Issued at 537 PM CST Sat Jan 14 2017 Don`t have a great deal of confidence in IFR VSBY and CIGS just yet as precip continues to battle the dry air at the surface. Since the RAP and HRRR tend to favor an MVFR forecast, have leaned that way for a little longer into the evening. However continued moisture advection over the surface high should lead to IFR CIGS so have followed the bulk of the guidance and bring CIGS down. Timing the freezing rain and when CIGS worsen is the biggest uncertainty and have generally followed the consensus. However amendments are likely as the event unfolds. && .TOP WATCHES/WARNINGS/ADVISORIES... Ice Storm Warning until midnight CST Sunday night for KSZ024-026- 035>040-054-055. Ice Storm Warning until noon CST Monday for KSZ008>012-020>023- 034. Ice Storm Warning until noon CST Sunday for KSZ056-058-059. && $$ UPDATE...Wolters SHORT TERM...Sanders LONG TERM...Barjenbruch AVIATION...Wolters
Area Forecast Discussion
National Weather Service Tulsa OK
922 PM CST Sat Jan 14 2017 .DISCUSSION... Freezing Rain Advisory was previously extended through tonight, and current trends support keeping the Advisory along with the Ice Storm Warning configuration as they are. Additional light to moderate precip has begun expanding across east central OK and will continue to expand northeast over the next few hours, a trend supported by most hi-res models along with the 00z NAM. Surface temps are not likely to change much overnight, though an overall rise of a degree or so continues to be shown in most model guidance. Still this supports additional icing in many areas north of I-44 with heaviest accretions remaining near the Kansas border where sfc temps should remain a tad lower. It is likely that some areas will not warm above the freezing mark until after the warning expiration time of 12z...however signal has remained consistent that precip should decrease by that time and for the moment, feel that the current expiration time will suffice. Updated products have already been sent. && .PREV DISCUSSION... /Issued 542 PM CST Sat Jan 14 2017/ AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG. Ongoing IFR to LIFR conditions will continue through much of the forecast period with some improvement possible Sunday afternoon. Precip chances will remain highest for NE OK with periods of FZRA continuing through tonight for KBVO. PREV DISCUSSION... /Issued 312 PM CST Sat Jan 14 2017/ DISCUSSION... Earlier update had removed the Ice Storm Warning for a few counties in northeast OK and replaced with a Freezing Rain advisory as 32F line has held steady from north of Pryor to Tulsa to northern Creek county. Some additional light icing will occur in these areas the remainder of the afternoon...with surface temperatures expected to rise just a hair above freezing by this evening. A large area of freezing rain has blossomed across much of western and northwestern OK...the eastern fringes of this activity will impact areas northwest of I-44 this evening and into the overnight hours. Latest high-res NAM solutions look just a touch too warm with the surface temps in these areas...although the HRRR appears to have a reasonable handle. Plan on keeping the Ice Storm warning going for Pawnee...Osage...Washington...Nowata and Craig counties...with the most significant icing occurring in parts of Osage county near the KS border. Obviously this is very temperature dependent...and if any warming occurs then icing will decrease accordingly. Surface temperatures will warm above freezing by Sunday advance of a strong upper cyclone moving into west TX. Rapid moisture return ahead of this system will bring a very good chance of widespread showers and a few storms to the area mainly Sunday night into Monday. Mass synoptic fields suggests that the primary warm sector remains most to our south for this overall chances of thunder and any severe storms will be quite limited. The upper pattern remains quite active across the CONUS for next week...although the better moisture should be shunted south. Seasonal temperatures on Tuesday will be followed by a nice warming trend the rest of the week. Have kept the extended portion of the forecast dry for now. && .PRELIMINARY POINT TEMPS/POPS... TUL 33 52 51 63 / 80 30 80 40 FSM 44 61 52 67 / 30 20 60 70 MLC 37 60 57 67 / 60 30 90 60 BVO 31 48 46 61 / 90 60 80 40 FYV 41 57 52 62 / 50 30 60 70 BYV 38 53 48 63 / 60 30 60 70 MKO 34 55 52 67 / 80 30 80 60 MIO 31 51 49 63 / 80 60 80 60 F10 33 55 54 65 / 80 40 80 50 HHW 46 64 56 68 / 20 20 90 80 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...Freezing Rain Advisory until 6 AM CST Sunday for OKZ058-060-061- 064. Ice Storm Warning until 6 AM CST Sunday for OKZ054>057-059. AR...None. && $$ SHORT TERM...14 LONG TERM....99