Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/02/19

Area Forecast Discussion
National Weather Service Bismarck ND
857 PM CST Fri Feb 1 2019 .UPDATE... Issued at 855 PM CST Fri Feb 1 2019 Getting some flurries across the north this evening with the advancing cold air so added them to the forecast tonight/tomorrow morning in addition to the patchy to areas of fog. UPDATE Issued at 542 PM CST Fri Feb 1 2019 Mid to high clouds have overspread most of west and central North Dakota so will increase cloud cover for tonight. Lower stratus moving south along the Canadian border and expect their arrival across the northern sections of the state this evening, which is associated with cooler air. Current forecast looks good. && .SHORT TERM...(This evening through Saturday) Issued at 230 PM CST Fri Feb 1 2019 Forecast highlights in the short term period will be continued mild temperatures tonight and Saturday, with areas of fog tonight. Currently, broad ridge across the Rockies into the Great Plains results in zonal flow aloft over the region. Surface warm front over the central Dakotas with a cold front draped just north of the International border with low pressure centered over central ND. Very mild temperatures behind the warm front with 40s west and south central. Colder along to east of the front with temperatures in the 20s across my far east. Mid to upper level cloud cover increasing west into central. Surface cold front drops southward tonight as sfc low moves southeast, bringing with it a surge of low level stratus and likely fog development. Both the RAP & HRRR show this development in the evening/overnight hours. Dense fog will be very possible northwest into central and portions of the southwest, and will monitor for possible dense fog headlines tonight/Sat AM. Another area of sfc low pressure develops and moves into eastern MT/western ND Sat, developing with it another warm frontal zone which looks to bring enough WAA into my southwest with mid/upper 40s again possible. The WAA tomorrow will be confined to my southwest, with teens and 20s elsewhere for highs on Saturday. .LONG TERM...(Saturday night through Friday) Issued at 230 PM CST Fri Feb 1 2019 Highlights in the long term period will focus on a potential winter storm moving into the area late Sat night and impacting the region Sunday and Sunday night. This will be followed by an extended period of cold. 12Z models and associated WPC guidance have come in wetter with QPF, which closely matches trends with GEFS plumes which have clustered higher. QPF now looks to be fairly widespread 0.4 - 0.6", about a tenth to 0.15" higher than the last couple of model cycles. Collaborated modifying snow ratios with the strong CAA. This combined with the wetter trend has added around 2" of snowfall to our forecast for the Sunday/Sun night period. This now puts 6-9" north of I94, and 3-5" south for storm total amounts. After a collaboration call with WPC and local collaboration with FGF, we have opted to issue a winter storm watch. Will include the entire area for a couple of reasons. First to account for any further southward trends, and second to account for the blowing snow potential southeast. The watch will be valid from 12Z Sunday morning until 12Z Monday morning. There is definitely the possibility of snowfall totals coming down given the progressive nature of the S/WV, though hard to ignore the trend for higher QPF (and the great agreement amongst models with such) and the higher snow ratios, so we along with WPC and our western and eastern neighbors feel the watch is justified. Upper level jet dynamics associated with a jet streak lifting northeast across out region will see the strongest lift Sunday morning/afternoon. The overall threat for heavy snow banding still appears low given the lack of favorable midlevel frontogenesis and mid level lapse rates advertised. Blowing snow will be maintained in the forecast, especially Sunday night- Monday AM when models show strong northerly winds on the backside of the sfc cyclone. Afterwards, confidence remains high in wind chill hazards next week with the multi-model consensus also supporting highs below zero Monday through Thursday. Another opportunity for snow remains in the forecast on Tuesday and perhaps on Thursday associated with fast moving S/WV`s. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 542 PM CST Fri Feb 1 2019 A Cold front lying across northern North Dakota at 5 PM CST will move south tonight and Saturday. Deteriorating conditions from VFR to MVFR to IFR will follow the front due to low clouds and areas of fog. && .BIS WATCHES/WARNINGS/ADVISORIES... Winter Storm Watch from Sunday morning through late Sunday night for NDZ001>005-009>013-017>023-025-031>037-040>048-050-051. && $$ UPDATE...WAA SHORT TERM...NH LONG TERM...NH AVIATION...WAA
Area Forecast Discussion
National Weather Service Charleston SC
957 PM EST Fri Feb 1 2019 .SYNOPSIS... High pressure will prevail to the north tonight. Weak upper level disturbances are forecasted to affect the area this weekend. High pressure will then build across the region and persist through late next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Late this evening: Not much change to the previous forecast. Radar imagery shows that light precipitation is filling in nicely just to the south of the forecast area, and a number of observations sites are reporting light rain. However, recorded rainfall amounts are just a hundredth of an inch or so. Increased rain chances along and south of I-16 for the next several hours, but still don`t expect much if any rainfall accumulation. Overall, the new 02/00z NAM seems to be initializing the best while the hi-res RAP and HRRR seem to be struggling to capture the coverage of light rainfall. Previous discussion continues below. Early this evening: Surface analysis shows high pressure over the Atlantic extending back across the forecast area with a nearly stationary frontal zone well to the south that runs west to east across the Gulf of Mexico. Surface observations are hinting at the beginnings of a coastal trough, mainly across the Georgia coastal waters where winds have turned northeasterly. Radar imagery shows very light returns moving into southeast Georgia, though it does not appear that anything is reaching the ground. A notable precipitable water gradient exists across the forecast area, with values down around half an inch near Lake Moultrie, and values of an inch or greater just to the south of I-16. So, considerable dry air remains in place and will need to be eroded away before rainfall becomes too widespread. This will likely keep most land areas dry through sunrise, with the exception being southeast Georgia mainly along and south of I-16. The driver for precipitation development is a well defined mid-level shortwave tracking eastward along the Gulf Coast. For now, some confluence just to the north is maintaining the dry air. By sunrise Saturday, PVA will spread in from the southwest associated with the trough, and weak cyclogenesis will begin just off the north Florida coast. Models continue to struggle with this setup, with hi-res solutions like the HRRR and RAP showing virtually no rainfall through tonight while the GFS/NAM/ECMWF all show some degree of precipitation breaking out across the southwest periphery of the forecast area. Tried to create a blend of the two camps in rain chances, at least until radar trends become more apparent. Overall, made some adjustments to rain chances, but most other parameters did not need significant adjustments. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... Saturday: A mid-level short-wave with some vorticity embedded within it will move over our area from the morning into the afternoon. A second, stronger short-wave will approach from the west in the evening, reaching our area by daybreak Sunday. At the surface, high pressure over the Mid-Atlantic states in the morning will retreat while a coastal trough strengthens over/along the FL east coast. The bulk of the energy with this feature is forecasted to remain just offshore. However, the feature itself should brush our coastline into the afternoon hours, moving to the northeast along the coastline into the overnight hours. The bulk of the moisture will remain far offshore. Though, PWATs across our area will generally be above 1". Factoring all these variables, we have likely POPs brushing along the coastal counties during the day, tapering as one heads inland. The QPF reflects this. Though, rainfall amounts won`t be substantial. Highs will be a few degrees above normal, while lows remain very mild. One thing to note is if the position of the trough moves further inland than expected, then a substantial change to the POPS and QPF would be needed. Sunday: A mid-level short wave will be over the Southeast in the morning. This wave is forecasted to slowly move eastward during the day while amplifying. It is forecasted to develop into a low as it moves offshore overnight. At the surface, a coastal trough will generally be brushing along northern portions of our area in the morning. This feature will move away during the day, accelerating to the northeast into the night. At the same time, high pressure initially over the Mid-Atlantic states will gradually build southwards into the evening and overnight hours. The highest moisture will be located near Charleston in the morning, gradually lowering into the day and especially at night. POPs are generally in the chance category during the day with only a few hundredths of QPF expected. Conditions are expected to dry out overnight with gradually clearing. Highs will once again be a few degrees above normal. Lows will be above normal too. Though, not as warm as the previous night due to some clearing. Monday: The mid-levels will consist of a strengthening low off the Southeast coast. This low will be pushed away by building heights within semi-zonal flow over our area. At the surface, high pressure will be over the Southeast. In the Atlantic will be a departing low/trough. To the west will be a distant, approaching front. The high will dominate the forecast, bringing dry conditions with some clouds. The airmass does start to moderate, with highs rising about ten degrees above normal. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... A drier and warmer pattern is anticipated heading through at least the middle of next week as sfc high pressure settles over the Southeast under a ridge of high pressure building aloft. In general, afternoon temps should peak into the low 70s Tuesday, then mid 70s Wednesday and Thursday well ahead of a front approaching northern areas next weekend. Overnight lows will also trend warmer a few degrees each night, from the upper 40s/lower 50s Monday night to mid/upper 50s by Wednesday night. Although a few showers are possible across inland areas mid week, the best chances of precip appear to be next weekend should a front shift into the region. There is also a low threat of sea fog moving onshore into the immediate coastal areas mid to late week as light southerly winds and sfc dewpts approach 60 degrees over cooler shelf waters. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... VFR conditions should prevail through the overnight period. Then on Saturday, the chance for MVFR ceilings increases through the day as an area of low pressure develops offshore. Have started MVFR ceilings at KSAV at 13z and also brought in some showers by around midday. Guidance for KSAV would suggest that IFR ceilings will start in the afternoon, but confidence isn`t high enough to introduce quite yet. Instead, the forecast features low end MVFR for the latter part of the period. Ceilings will be slower to arrive at KCHS, and for now the forecast period is VFR. Did introduce a VFR ceiling at 20z, and as we get closer to 00z Sunday the chances for MVFR or lower will increase at KCHS as well. Extended Aviation Outlook: Weak upper level disturbances along with a coastal trough could bring periods of flight restrictions Saturday into Sunday. VFR will prevail Monday through Wednesday. && .MARINE... NE flow will gradually strengthen overnight as the coastal trough strengthens off the FL/GA coast. Weak upper level disturbances are forecasted to move over the region this weekend. This will cause a coastal trough initially along the east coast of FL to move northeastward, passing along our coast Saturday. The trough should continue it`s movement to the northeast and away from our area on Sunday. Winds are expected to be at their strongest Saturday, sustained at perhaps no more than 15 kt across the waters. Winds should then ease a few kt Sunday. Inland high pressure will build on Monday, causing winds to veer with speeds at or below 10 kt. Seas will generally range between 2-4 ft into early next week, but we could see waves as high as 5 ft in the offshore GA waters late Sunday. High pressure should then extend across the waters by Tuesday, then persist into the middle of next week. Winds and seas will remain well below Small Craft Advisory levels during the transition, but light southerly winds should develop heading into mid week. These winds along with dewpt temps approaching 60 degrees, could become more favorable for sea fog over cooler shelf waters mid week. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...BSH SHORT TERM...MS LONG TERM...DPB AVIATION...BSH/MS MARINE...JRL/MS
Area Forecast Discussion
National Weather Service Sioux Falls SD
556 PM CST Fri Feb 1 2019 .SHORT TERM...(This evening through Saturday) Issued at 335 PM CST Fri Feb 1 2019 Difficult temperature forecast for the next few days with strong inversion across the area. NAM is very aggressive with near surface moisture from melting snowpack, and has widespread fog developing overnight tonight. GFS and HRRR suggest the potential developing across western Iowa, and lifting north into the forecast area early on Saturday morning. Have patchy fog mention across the south, but think it will be fairly shallow except for northwest Iowa. Have lingering mention of fog across northwest Iowa Saturday morning. Where fog/stratus clear on Saturday, should be a nice day with 925 hpa temperatures warming towards 10C. Won`t be able to realize the full value of warming, but have raised forecast highs in the south- especially where snow cover has cleared. Potential for fog and stratus continues to plague the forecast area Saturday night, especially in the east. Have added mention of fog and increased sky cover Saturday night into Sunday. .LONG TERM...(Saturday night through Friday) Issued at 335 PM CST Fri Feb 1 2019 Warm front lifts north on Sunday towards the I-90 corridor. Stratus is expected to increase in depth throughout the day ahead of the next approaching low. With strong lift above the surface, could see drizzle/freezing drizzle develop, especially during the evening hours Sunday night as isentropic lift increases. Dry layer in the mid levels of the atmosphere makes the dendritic layer difficult to utilize, and as such, looks like a drizzle/freezing drizzle event ahead of cold front moving through late Sunday night. Forecast highs on Sunday will be key, as locations north of I-90 look to mainly remain below freezing. With the increasing lift Sunday evening, could see an icing event develop. Right now best chances for significant icing appear to be across southwest Minnesota. Have raised icing amounts there to 0.1-0.15", and will heighten wording in the HWO. With the passage of the front, expect northwest winds to rapidly increase and precipitation to quickly transition to snow. Lift quickly pulls away from the region on Monday morning and the region is left with strong and gusty winds. Have raised winds by blending in MOS values. Tuesday into Wednesday continues to look active with unsettled pattern across the area. A series of waves look to work through the region possibly creating periods of light snow across the region. This threat looks to continue till Arctic front works through the region Wednesday night. Behind the front, much colder air works into the region. Will likely need a wind chill advisory for much of the area as wind chills hover in the 15 to 30 below range much of late next week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 555 PM CST Fri Feb 1 2019 Clear skies and light winds will continue overnight. During the early morning hours, there is a chance of fog development. This is not a high confidence situation, given continued light surface winds in the 5 to 10 kt range may promote marginal surface mixing, but with snow melt during the daytime hours, the boundary layer is likely moist enough to create at least patchy fog. Those in northwest Iowa have the highest chance for more widespread fog, given more robust moisture advection. By 02/1600z, daytime mixing should be sufficient to dissipate any fog. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ SHORT TERM...BT LONG TERM...BT AVIATION...VandenBoogart
Area Forecast Discussion
National Weather Service Huntsville AL
909 PM CST Fri Feb 1 2019 .NEAR TERM...(Tonight) Issued at 909 PM CST Fri Feb 1 2019 An interesting forecast continued to unfold across parts of the area this evening. A plume of mid level moisture present in a west to east orientation across southern Tennessee was actually causing light showers via local radars from east of Memphis, along the MS/TN border, across middle Tennessee (so far north of Lincoln, Moore and Franklin counties). Only trace amounts of rain have been noted from the very few rainfall reports received near Memphis, suggesting most of it was remaining aloft. The bad; none of the recent models were really picking up on this light rain. However, moisture and relative humidities in the low/mid atmosphere at 7000-10000 ft were supportive of this. The 290-295K isentropic region from the RAP and NAM nicely indicated this; but did not reflect precipitation as a result. Those models also indicated that the moisture should downglide/fade during the course of the late evening and overnight (something the models may be accounting for), thus this should only be a short term affair. The RAP was drying the 295K region faster than the NAM. We have added a slight chance of showers for parts of our middle TN group given how close the showers are. Again, rain chances should fade during the overnight as drier air works in from the ESE. Given a return to a more zonal pattern and warmer atmosphere, not as cold night time lows are forecast. Night time lows in the mid/upper 30s are expected, with maybe a spot or two briefly freezing before sunrise on Saturday. .SHORT TERM...(Saturday through Sunday) Issued at 237 PM CST Fri Feb 1 2019 Tomorrow, a shortwave will weaken as it moves across TX and the Southern MS Valley. Moisture however will increase ahead of this feature. Dewpoints will return to the 40s on Saturday and the 50s by Sunday. Even though there will be some moisture return on Saturday, forecast soundings are still pretty dry so continued to keep precip out. The shortwave will move across the TN Valley Saturday night, bringing additional moisture with it, thus additional cloud cover. Models disagree with how much rain we could receive (or any at all) on Sunday/Sunday night due to how they are handling the shortwave and ridge building in behind it, so went with a slight chance for most of the CWA at this time. Look for above normal temps through the weekend! Daytime highs will reach the lower 60s on Saturday with overnight lows in the lower 40s. Although heights will rise on Sunday, cloud cover will keep daytime highs in the lower 60s but overnight lows a little warmer in the mid 40s to lower 50s. For reference, our normal high temps are in the lower 50s for this time of year. .LONG TERM...(Sunday night through Thursday) Issued at 237 PM CST Fri Feb 1 2019 Next week, the medium range models are in fair agreement that a large scale 5h ridge will build across the Gulf of Mexico through the FL peninsula and Bahamas. They diverge on the strength of the ridge, with the operational GFS being most dominant over the FL peninsula. The ridge will produce persistent southwest to westerly flow across much of the southern CONUS, and either shearing or limiting the southward latitude of trough progressions across the central and northern CONUS. The ECMWF is still pushing the arctic front southeast through on Friday (day 8). At this point, favoring the GFS given the upper pattern which may keep the local area in a warm sector airmass for the entire week. Blended guidance will temper the warm sector by Thu night-Fri in our NDFD forecast however, so this is subject to change...alot! On Tuesday a very shallow cool air may temporarily reach southern TN or north AL before lifting right back north Tuesday evening. But then the arctic boundary may remain far enough northwest Wed and Thu to keep the area rather rain-free. Will keep blended guidance for PoPs, but these are relatively low chances. And, given instability increasing, won`t rule out a few thunderstorms Wed-Thu. The heaviest rain band will likely be to our northwest this forecast however. Highs could easily reach the u60s-l70s next week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 552 PM CST Fri Feb 1 2019 An area of mid level clouds ~7-9 kft were in a west-east axis across southern TN. Some of the clouds over western/middle TN had ceilings down to MVFR ~2-3kft. Forecast trends have these mid-level clouds becoming scattered in the overnight. Otherwise, scattered high altitude clouds are possible after daybreak on Sat. Winds through the TAF should remain light, mainly from the SE in the 2-5kt range. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...RSB SHORT TERM...JMS LONG TERM...17 AVIATION...RSB For more information please visit our website at
National Weather Service Wilmington OH
952 PM EST Fri Feb 1 2019 .SYNOPSIS... High pressure centered to the east will provide dry weather tonight. Dry weather is forecast to continue through Saturday and Sunday as the high settles along the Atlantic Coast. Rain showers are expected Monday along a weak cold front traveling from the west. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Patches of stratocumulus over the area have mostly dissipated or moved east, though one area of 2kft-3kft clouds remains parked over Wilmington. Just south of the ILN forecast area (and along the southern border) is an area of lower stratus clouds, generally below 1500 feet in height. These clouds have begun to expand, and visibilities have been dropping below them, and especially along their periphery in the Louisville. On the 00Z KILN sounding, discounting the slight bit of moisture associated with the stratocumulus, the moisture lower in the sounding (below 950mb) is rather shallow. There remains an expectation that fog and stratus will move into the area during the overnight hours, generally spreading in from the southwestern sections of the CWA. What makes the forecast a little bit uncertain is that there are discrepancies between the current observations and the way the HRRR (usually a very useful model for fog development) is depicting the scenario. The 21Z SREF fog probabilities actually seem a better fit for the current scenario. These suggest that fog will overspread most of the forecast area, but the potential for significantly reduced visibilities may be most prevalent in the western third of the CWA. Given that this is not really a pure radiation fog scenario (with theta-e advection beginning on light southeasterly flow) the lack of moisture further east and northeast may limit fog potential to some degree. Temperatures and dewpoints are generally expected to remain steady for a few hours, then rise as the rest of the overnight period goes on. No major changes were required to the previous forecast, outside of lowering sky cover to account for current conditions. Previous discussion > Surface analysis shows high pressure centered over Lake Erie. Given the subsidence and lack of forcing and deep moisture around the high, there should be no precipitation tonight as the high moves to Pennsylvania. However, models, observations and satellite imagery show persistent clouds due to moisture trapped under an inversion around 1000 ft AGL. In addition, fog may form as slightly warmer air advects over snow cover. Mitigating factor for dense fog will be winds staying above calm as the pressure gradient becomes more prominent later tonight behind the high. Overnight lows will be tricky due to the balance between warm advection and cold snow cover. We should see readings fall off to the teens and twenties early this evening, before a modest rebound later tonight brings temps up into the 20s across the area. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... High pressure will settle along the Atlantic Coast on Saturday. With models showing a nearly saturated boundary layer and a persistent low level inversion, cloudy skies are likely to persist. No precip is expected in a regime still lacking forcing and deeper moisture. Fog will be possible again Saturday night due to continued warm advection over snow. Temperatures may rise to the 30s and 40s by late Saturday afternoon. However, went below guidance because warmer readings will be hard to attain due to cold ground and cloud cover. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Sunday temps are forecast to rise a bit faster than previously forecast once any lingering fog burns off within a few hours of sunrise. Still expect many areas to see temps rise into the low to mid 50s by mid afternoon, but now expecting slightly cooler conditions for Sunday night. Maintained a dry forecast during the day and overnight attributed to southern Appalachia high pressure influence and veering surface winds. Only expecting some 850 mb clouds instead of precip potential beneath an increasingly muted mid level shortwave. Still on track to see low pressure progress toward the Great Lakes on Monday brining showers along and ahead of a trailing cold front. Winds will pick up mid morning ahead of the front as the surface pressure gradient tightens up by 15Z producing gusts to around 20-25 kt. WAA will be weaker on the warm side of the front causing temperatures to be a bit cooler than the last forecast update. The first wave of showers still appears coupled with a pre-frontal surface trough with an earlier arrival of the front. GFS still more bullish on QPF, thus maintained blended pops. No significant changes in thunder potential which still appears low. One interesting feature that is becoming more defined is a stronger 850 mb jet intersecting the through which could slightly extend the duration of the trailing precip. Tuesday will see a return to CAA advection pattern from stronger NW flow as surface diffluence sets up from a developing lee-side low along the Rockies in conjunction with anticyclonic flow from eastward traversing Canadian high pressure to the north. The high does seem to be slowing along its Atlantic heading which will increase the duration of dry air persistence ahead of the advancing system potentially delaying the onset of precipitation. This would help increase the chance for wintery form precip. Delayed higher pops a smidge ahead of the precip shield due to the drier air out ahead. Coverage of showers will expanded throughout the late overnight becoming more widespread by daybreak. Models have come in colder behind Tuesday`s cold frontal passage. As such, embedded short wave energy and return moisture flow may bring some wintry pcpn to northern sections by Tuesday night into Wednesday morning before temperatures warm enough into Wednesday afternoon. Even so, east/southeast flow, clouds, and pcpn chances increasing on Wednesday will keep temperatures down some, especially north. Forecast highs will range from the upper 30s north to the lower 50s far south. Models are keying on a mid level trough to move from the northern/central Plains into the Great Lakes and Ohio Valley for the period Wednesday night into Friday. This process will bring a wave of low pressure through the region along with the likelihood of pcpn. In addition, forecast pwats are concerning with various outputs forecasting 1 to 1.50 inches moving into the Ohio Valley. This may pose a flooding concern to the region, so we will be keeping a watch and will update the forecast accordingly. Still a little to early for the HWO, but later forecast may dictate this be placed in this product. There may be a chance of thunder with the low, but placement differences preclude placing it in the forecast at this time. Colder air advecting into the region Thursday night into Friday may chance the rain to snow before tapering off. A blend of models have been used for a non-diurnal cycle period. Highs on Thursday are forecast to range from the lower to mid 40s far northwest to near 60 southeast, cooling to highs from near 30 northwest to the near 40 southeast on Friday && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... The main concern through the forecast period is the potential for fog overnight. MVFR ceilings currently in place have been breaking up, and a period of prevailing VFR conditions is expected to occur for all of the TAF sites. As the night progresses, however, visibilities will begin to drop. There is high confidence in reduced visibilities of MVFR to IFR, with slightly less confidence in how low the visibilities will get. However, there is at least some potential for dense fog, particularly for KCVG/KLUK/KDAY. Some MVFR/IFR ceilings may also develop during this time frame, though for the most part the aviation conditions should be dictated by the visibilities. Whatever fog develops should be slow to improve on Saturday morning, though eventually visibilities should get to VFR at all sites (though MVFR ceilings may persist). Going into Saturday night, there is some potential for fog and low ceilings to develop again. Winds through the TAF period will start out from the east to southeast, and will shift to the south / southwest by Saturday morning. Speeds are expected to remain at or below 10 knots. OUTLOOK...MVFR/IFR conditions are expected to continue into Sunday. MVFR conditions are possible again at times from Monday through Wednesday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Coniglio NEAR TERM...Coniglio/Hatzos SHORT TERM...Coniglio LONG TERM...Hickman/KK AVIATION...Hatzos
Area Forecast Discussion
National Weather Service Marquette MI
652 PM EST Fri Feb 1 2019 .SHORT TERM...(This evening through Saturday) Issued at 244 PM EST FRI FEB 1 2019 Water vapor imagery and RAP analysis shows a shortwave moving ese from northern Manitoba toward James Bay. WAA ahead of this feature and its sfc low over ND has led to light snow over portions of northern MN and NW Ontario this afternoon. WAA in sw flow under mostly sunny skies has also allowed Upper Mi temps to rebound into the double digits above zero this afternoon after overnight lows in the teens to 20s below zero at many places (even a few spots has mins of -30 or lower). Tonight into Saturday, as a weak cold front sags southeast from Ontario late this evening/overnight WAA ahead of it will spread light snow into mainly the northern portion of Upper Michigan. With models indicating the best forcing ahead of the Manitoba shortwave staying well north into Ontario, any snow accumulations over our area should be minimal (less than an inch) with the better chance for accumulating snow across the Keweenaw Peninsula and eastern Upper Michigan. Temperatures tonight shouldn`t drop too much due to increasing cloud cover and mixing from southwest winds. Expect readings from 5-12F, coolest inland. Winds shifting light and northerly behind the front on Saturday will keep cloud cover around, although air mass probably not cold enough for lake effect other than maybe scattered flurries. Expect highs on Saturday mainly in the lower to mid 20s. .LONG TERM...(Saturday night through Friday) Issued at 335 PM EST FRI FEB 1 2019 Focus remains on a light icing event Sat night into Sun and on a potentially significant winter system Sun night through Mon. Sat night and Sun: WAA/isentropic ascent will lead to areas of freezing drizzle Sat night into Sun (only over the E by afternoon). Temps will be warming later Sat night through Sun, with highs in the mid to upper 30s, but with very cold road surface temps drizzle will continue to freeze to untreated roads even after air temps rise above freezing. Accumulations are only expected to be very minimal, but could lead to slick spots on untreated surfaces such as roads and sidewalks. Sun night and Mon: A strong shortwave will drive a roughly 1000mb surface low that will move from SW WI at 15Z Mon to near Lake Huron by 00Z Tue. Models have fallen into decent agreement, with the GFS being the overall favored solution at this time. Unfortunately, even with decent agreement, the details are very dependent on exact track and temperature profiles, so confidence in exact numbers and impacts remains limited. Current thinking is that the NW U.P. (very roughly NW of a line from Marquette to Watersmeet) will see somewhere in the range of 4-7 inches of wet, heavy snow, with peak intensity from late Sun night into Mon afternoon. This will be impactful from a standpoint of wet, heavy snow falling heavily for a time. Areas just S of that line are forecast to see a mix of light freezing rain and marginal amounts of wet, heavy snow with peak intensity on Mon morning and afternoon. The combo of snow and ice could be quite impactful with regard to travel mainly. Doesn`t look like enough ice on elevated surfaces to cause significant impacts outside of travel. Farther S (roughly along and S of a line from Iron Mountain to Rock to Seney, the forecast is for mainly rain with little to no snow. High temps are forecast to be in the low to mid 30s, but any areas that see above freezing temps will likely only see those for a couple hours or so. Even when temps rise above freezing in those areas, ground surface temperatures will remain below freezing, which will result in continued freezing rain on roads and sidewalks. Precip type and amounts are highly in question over roughly the SE half of Upper MI. Snowfall is more certain over the NW half. Of course, any shifts in the track or changes in airmass will result in significant changes to the forecast, especially over the SE. There is potential for freezing rain to be all snow over the SE as models have generally been trending cooler with temp profiles. Will issue an SPS to highlight this event as well as ice potential Sat night and Sun. In addition to the precip that falls during the event, air temps look to fall rather quickly from NW to SE as strong CAA kicks in behind the system. Could see single digit temps over the NW by early afternoon and all areas should drop into the teens by mid-evening Monday. Any wet snow or liquid will flash freeze as the cold air comes in, potentially adding additional travel hazards. Blowing snow will develop along Lake Superior as winds pick up Mon morning into Mon evening, then gradually diminish Mon night into Tue morning. Mon night through Fri: Generally looking at marginal lake effect snow and potentially some system snow. The very cold airmass shown by models yesterday is not as cold in current runs, but below normal temperatures are generally expected. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 652 PM EST FRI FEB 1 2019 A band of -sn will brush the area this evening, most likely affecting KCMX and perhaps KSAW. The period of -sn will be short, only lasting a few hrs at most. At KCMX, conditions may fall to IFR. Otherwise, VFR conditions and LLWS will likely prevail at KIWD/KCMX/KSAW this evening. A weak cold front will drop s across the area overnight and Sat morning. As it does so, expect MVFR cigs to set in at all terminals. Some -sn/flurries will also occur at KCMX. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 244 PM EST FRI FEB 1 2019 Winds stay below gales until Monday when northeasterly gales of 35 to 40 knots develop on the backside of a low moving through the Upper Great Lakes. Gales subside by Tuesday morning. Where the lake is ice free, heavy freezing spray will continue into tonight, before subsiding this weekend as temperatures moderate. The heavy freezing spray makes a return early next week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Heavy Freezing Spray Warning until 7 AM EST /6 AM CST/ Saturday for LSZ162-240>251-263>267. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...Titus AVIATION...Rolfson MARINE...Voss
Area Forecast Discussion
National Weather Service Nashville TN
740 PM CST Fri Feb 1 2019 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... Radar imagery this evening shows numerous showers have developed across our southern counties generally along a line from Linden to Altamont. Have had to greatly increase pops across the area for the evening as nearly all model guidance had a massive fail and missed this shower activity. Exception is the HRRR and have relied on it for guidance, which shows these showers gradually winding down through the evening while the overall area of precip lifts slowly northward, with some sprinkles possible after midnight. Have also raised lows a few degrees for tonight due to the widespread cloud cover. Updated grids and zones already out. && .AVIATION... 00Z TAF DISCUSSION. VFR conditions continue for BNA/MQY this evening, with CKV wavering in/out of MVFR CIGS and CSV holding at IFR CIGS. The overall trend will be for all sites to go MVFR late tonight, around 04z or after. CIGS will eventually improve to VFR everywhere mid- morning to mid-day on Saturday. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......Shamburger AVIATION........Schaper
Area Forecast Discussion
National Weather Service Tulsa OK
739 PM CST Fri Feb 1 2019 .UPDATE... The main change this evening was to reduce PoPs and insert some patchy fog. See discussion below. && .DISCUSSION... The transition from a cold regime to a warmer one continues today. Temps and dewpoints continue to rise as low level southerly flow persists, and cloud cover has been stubborn to go away. While there will be breaks in the cloud cover here and there, this forecast will maintain a mostly cloudy to cloudy wording. The trends in the HRRR have backed down on the fog potential for tonight overall. A stronger southerly 925mb wind exists tonight, unlike last night, which could help keep the BL mixed just enough. Nevertheless, some patchy fog was put in the grids for after midnight. With no discernable signal in the short term data for precip tonight, PoPs have been dropped. Updated text products sent. Lacy && .PREV DISCUSSION... /Issued 532 PM CST Fri Feb 1 2019/ AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG. MVFR ceilings will continue this evening for the eastern OK TAF sites, with IFR conditions developing this evening for the northwest AR terminals. There may fog again at the NW Arkansas sites, along with patchy drizzle overnight into early Saturday morning. South winds will increase by mid day Saturday, with gusts to 15-20kt possible at some of the sites. PREV DISCUSSION... /Issued 257 PM CST Fri Feb 1 2019/ DISCUSSION... Upper low currently located over southern NM will continue to shift east tonight into Saturday. Patchy areas of light drizzle and/or light rain will remain possible through the Saturday before wave weakens/shifts east of the region. Strong southerly winds will likely develop on Sunday as cyclogenesis develops along the lee of the Rockies. Broken/overcast conditions will likely persist for much of the day, limiting gust potential to some extent. At least a limited fire weather danger threat will remain but increasing low level moisture will likely mitigate a more significant threat. Temperatures will remain well above normal Sunday into Monday night ahead of next cold front that will move into northeast Oklahoma Monday morning. Precipitation chances should remain low with frontal passage as boundary stalls across southeast Oklahoma /west-central Arkansas Monday afternoon. Warm front will begin to lift back north on Tuesday with the potential for scattered showers/isolated thunderstorms along and south of front in warm sector into the day Wednesday. Still some significant differences in the operational models concerning strong upper level storm system that will impact the region Thursday into Friday. Generally trended toward the more compact and progressive ECMWF solution that sweeps strong cold front through the area on Thursday. With this scenario, overall winter weather potential would remain limited as showers/thunderstorms move east before the colder air moves in behind front. && .PRELIMINARY POINT TEMPS/POPS... TUL 48 63 54 68 / 10 20 10 10 FSM 46 60 49 67 / 10 20 20 10 MLC 52 63 54 69 / 10 20 20 10 BVO 45 63 49 67 / 10 20 10 10 FYV 44 59 48 64 / 10 20 20 10 BYV 44 61 48 66 / 10 20 20 10 MKO 48 62 51 68 / 10 20 10 10 MIO 46 62 52 67 / 10 20 10 10 F10 49 63 52 69 / 10 20 10 10 HHW 52 61 51 69 / 10 20 20 10 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ LONG TERM....30