Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/09/18

Area Forecast Discussion
National Weather Service La Crosse WI
545 PM CST Sat Dec 8 2018 .SHORT TERM...(Tonight through Sunday Night) Issued at 143 PM CST Sat Dec 8 2018 Another day of stratus across the area with temperatures sitting in the teens to middle 20s. Loop of GOES Visible however, does show this stratus thinning out some with the ground showing up beneath it. In addition, loop was showing showing a slow northeast push of the clouds. If this continues, and RAP 0.5-1km RH trends work out, we will see some clearing this evening, given influx of drier Plains air on southwest winds of 10-15mph in that layer. We will then be watching a mid-level focus/closed low dropping south from the Northern Plains tonight into the Central Plains. Some cirrus from this feature looks to push through the area but should end up mostly clear/mostly sunny tonight into Sunday. Otherwise, plan on lows tonight in the lower/middle teens and highs Sunday in the upper 20s to lower 30s. Mid-level ridge of high pressure builds back into the area as that closed low continue to sink southward away from the area. Continued mostly clear Sunday night with drier west- southwesterly flow. Look for lows again in the teens. .LONG TERM...(Monday through Saturday) Issued at 143 PM CST Sat Dec 8 2018 A mid-level trough/weak surface low passes just to our north Monday. Other than a few higher level clouds, skies should remain mostly sunny with highs topping off n the 25-30 degree range. Strong mid-level ridging on Tuesday will keep the area dry Tuesday with some increasing high clouds ahead of an approaching trough over the Northern Plains. Highs are expected to be in the middle 20s to the lower 30s. A chance of light snow or rain/snow mix moves in Wednesday as that Northern plains trough makes its way across the area. Plan on highs in the 30s. Another trough rolls across the region Thursday, keeping a chance of light snow or rain/snow mix in the forecast. Otherwise, look for highs again in the 30s. Although ECMWF and GFS are in fairly good agreement in keeping a strong low and associated precipitation well south and east of the area Friday, The GEM keeps the system tied with northern stream energy and spread precipitation well into our area. Will hold onto 30-40 pops for now and let models decipher with later runs. GFS and ECMWF build a ridge into the area on Saturday while the GEM keeps closed low overhead with light snow. Will keep a low-end pop and again, let models work this out with time. Otherwise, temperatures look to be right around normal or even a couple degrees above Friday and Saturday with highs in the upper 20s to middle 30s. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 545 PM CST Sat Dec 8 2018 Satellite imagery late this afternoon is finally providing some hope that the low clouds may clear out of the area. The clouds are caught in the low level southwest flow between the back side of the ridge that was just east of the area and the area of low pressure dropping south across the Dakotas. The clouds are progressing to the northeast and expect this trend will continue through the night, although most likely at a slower pace that previously expected and will hold the MVFR ceilings for most of the evening at both airports. Once the low clouds move out, some concern for fog development. The visibilities are currently in the 5 to 9 mile range already but hoping the light south winds will create enough mixing to keep any fog from forming. Also, not really seeing a signal in any of the short term meso-scale models for widespread fog formation overnight. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...04
Area Forecast Discussion
National Weather Service Charleston SC
951 PM EST Sat Dec 8 2018 ...HEAVY RAINFALL AND TIDES REACHING NEAR MAJOR FLOODING THRESHOLDS IN CHARLESTON HARBOR COULD PRODUCE WIDESPREAD FLOODING IN DOWNTOWN CHARLESTON SUNDAY MORNING... .SYNOPSIS... A strong low pressure system will move through the area tonight through Sunday. High pressure will gradually build in from the west early next week. A cold front may approach the region by the end of the work week or into early next weekend. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... No additional changes were made from the early evening update other than some minor grid tweaks. A highly complex surface pattern is in place this evening featuring strengthening cold air damming inland, a sharping coastal front offshore and low pressure located near the mouth of the Mississippi River at 08/23z. The low is forecast to track just inland along the northern Gulf of Mexico coast tonight and along the Georgia and South Carolina coasts Sunday morning. AS the low approaches, widespread precipitation will develop across the Southeast U.S. featuring heavy snows across western North Carolina, northeast Georgia and the South Carolina Upstate with moderate to heavy rainfall across the remainder of the region. A variety of sensible weather and hazards will impact Southeast South Carolina and Southeast Georgia tonight as the low draws closer. Details on these specific hazards are found below: Temperatures: The onset of diabatic cooling within the wedge has accelerated temperature falls more than expected this evening. The latest RAP wet-bulb progs suggest temperatures really only have a few more degrees to cool before leveling out, so opted only nudge lows down a few degrees. As the low approaches, it appears the low will track close enough to the far southern and coastal zones to draw warmer air in from off the Atlantic, even as the inland wedge hold tight. It was decided to introduce some rising temperatures during the early morning hours, but not quite as warm as the RAP and H3R consensus would suggest. This will have to be watched as this warmer trend has been a consistent signal in a number of the HREF members. Rain: The lower troposphere is steadily moistening this evening as light rain continues to develop. Most stations are reporting light rain with vsbys >6 miles, but are still measuring several hundredths. Rain intensity is expected to increase after midnight as low-level convergence intensifies across the coastal counties as multi-layer moisture transport and isentropic assent intensify atop the CAD region. The rain will likely become locally heavy at times right ahead of the surface low, so a "rain heavy at times" qualifier has been been introduced into the weather grids. There is some concern that hourly rainfall rates could become high enough as high tide approaches to create some flooding concerns, but opted to hold off on a Flash Flood Watch at this time. Wind: Early evening observations show winds are already gusting 35 mph along the coast from roughly Edisto beach northward. High resolution guidance with support from both the NAM and GFS show a nasty wind maximum working up along the Charleston County coast overnight into the mid-morning Sunday ahead of the surface low. This should support winds of 20-30 mph with gusts to 40-45 mph across Charleston County and into the Edisto Beach area. A Wind Advisory has therefore been issued with the greatest impacts expected to occur across the beach communities between McClellanville and Edisto Beach, including areas around the Charleston Harbor. The elevated bridges around Charleston Metro will also be exposed to these winds. For Lake Moultrie, northeast winds 15-20 kt with gusts 25 kt will persist and a Lake Wind Advisory remains posted there. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... Sunday and Sunday night: a vigorous surface low pressure system is shown by all models to be near or just off the GA coast by 12z Sunday, then move rapidly northeast away from the area Sunday afternoon. The day should start with widespread rain, possibly heavy at times, then tapering off during the afternoon. Given the rain, cloud cover and cold advection behind the storm during the afternoon, temperatures are not expected to climb much from the morning, only reaching the lower to mid 40s inland to the lower to mid 50s near the coast. Still expect storm total rainfall to be 1 to 3 inches, with lower amounts possibly over the southeast GA zones. Depending on how heavy the rainfall comes down, there could be some localized ponding/flooding of low lying areas and roads, especially Sunday Morning. Breezy northeast winds in the morning are expected to back to northwest and decrease some during the afternoon as the storm pulls away to the northeast. By Sunday night, the surface low moves well to the northeast, but at upper levels, a broad upper trough and associated moisture stick around, especially over the northern half of the region. Therefore, have kept chance PoPs over the north and slight chance to low end chance well to the south through the night. Lows by morning in the mid 30s, except around 40 closer to the coast. Monday and Monday night: A broad upper trough and some moisture remain over the area. This will keep conditions unstable enough to warrant mention chance of light showers through the period, tapering off Monday night. Highs will be quite cool, only in the lower to mid 40s most areas with mostly cloudy/cloudy skies. Clouds should gradually diminish through the night as the upper trough moves east with lows cold in the lower to mid 30s. Tuesday: The upper trough looks to finally move east of the region with deep layer ridging building from the west. Expect skies to clear, with temperatures topping out in the lower to mid 50s, which is still about 10 degrees below seasonal normals. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Any lingering precipitation should end by daybreak Wednesday after the secondary shortwave moves offshore. Temperatures will moderate mid to late week as surface high pressure moves east. A cold front is expected to bring another round of rain to the area Friday and Friday night, followed by cooler high pressure. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... IFR cigs will quickly overspread the terminals this evening as light rain blossoms over the region. Rain intensity will steadily ramp up overnight with periods of heavy rainfall likely setting up at both KCHS and KSAV after 09z as low pressure approaches from the southwest. Steadier rains will end from southwest to northeast Sunday morning as low pressure pulls away. Gusty winds near 25 kt will continue for much of the period. Extended Aviation Outlook: Sunday: Still expect MVFR to possibly periods of IFR conditions possible, which is also coincident with the timeframe for widespread rainfall, possibly heavy at times. Also, gusty northeast winds, backing to northwest later in the day. Sunday night through Monday night: MVFR ceilings will be possible as the area remains an upper level trough with the threat for scattered showers. Tuesday and Wednesday: Conditions expected to improve to VFR as deep layer ridging moves over the area from the west. && .MARINE... Buoy and pilot boat reports indicate gales have spread south across the entire local marine area and Gale Warnings have been expanded south to include the two Georgia marine zones. The Charleston Harbor Pilot boat recently reported NE winds 30-35 kt with seas 7 ft about 12 miles east of the Charleston Harbor entrance. High surf: Seas across the Charleston County waters are expected to build into the 7-10 ft range late tonight into Sunday morning. This could produce 3-5 ft breakers along the Charleston County coast during this time and a High Surf Advisory could be needed. Sunday: Models continue to show a strong northeast gradient, which is expected to produce marginal gale conditions over the Charleston coastal waters, where a gale warning remains in effect. There could be marginal/short lived Gale conditions, especially within gusts, near the mouth of Charleston Harbor, but to marginal to go with a Gale Warning at this time. Otherwise, solid Small Craft conditions all other areas through the day. Sunday night: the surface low continues to pull away, with a gradual weakening of winds, but still 15 to 20 knots from the northwest, with higher gusts. Seas may force a Small Craft Advisory to remain posted for outer waters beyond 15 nm in SC and the offshore GA waters. Monday and Tuesday: High pressure gradually builds from the west, but north-northwest winds remain in the 15 to 20 knot range. Again, with offshore flow, seas could linger around 6 ft beyond 15 nm offshore, which may require the issuance of an extended Small Craft Advisory for marginally high seas. Tuesday night through Thursday: High pressure slowly builds over the area with decreasing winds/seas below highlight levels. && .HYDROLOGY... Rainfall totals of 1-2" across southeast Georgia and 2-3" over southern South Carolina are expected through Sunday. Rainfall rates will probably not be high enough to cause significant flash flooding. However, there is concern that moderate to potentially heavy rain will occur around the Sunday morning high tide, which could exacerbate existing saltwater flooding along coastal locations, particularly in Southeast South Carolina. Longer term, we expect additional rivers to rise above flood stage and ongoing flooding to worsen. && .TIDES/COASTAL FLOODING... The latest tidal predictions have come down slightly since the 12z run and tides are now expected to peak at 7.9 ft MLLW or about 0.1 ft below major flood thresholds. It is very possible the latest run is underestimating the degree of gales along the Charleston County coast, which may eventually push tides above 8.0 ft MLLW. However, confidence is not high enough to justify an upgrade of the Coastal Flood Watch to a Coastal Flood Warning at this time. The final call will be made by the incoming overnight shift. The combination of moderate to locally heavy rainfall and high tides on the high-end of the moderate flood range could still a yield a fairly nasty situation in Downtown Charleston tomorrow morning. Guidance has also been indicating the tides could reach marginal Coastal Flood Advisory during the Monday morning high tide, but too marginal to get too specific at this time. Stay tuned for the potential for additional Coastal Flood Advisory issuances. && .CLIMATE... Rainfall records for 9 December: KCHS: 0.64/1948 KCXM: 0.99/1948 KSAV: 2.44/1885 && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...Lake Wind Advisory until 11 AM EST Sunday for SCZ045. Wind Advisory until noon EST Sunday for SCZ049-050. Coastal Flood Watch from 6 AM EST Sunday through Sunday morning for SCZ049-050. MARINE...Gale Warning until 8 AM EST Sunday for AMZ352. Gale Warning until 7 PM EST Sunday for AMZ350. Gale Warning until 5 AM EST Sunday for AMZ354-374. Gale Warning until noon EST Sunday for AMZ330. && $$ ST
Area Forecast Discussion
National Weather Service Duluth MN
943 PM CST Sat Dec 8 2018 .SHORT TERM...(This evening through Sunday) Issued at 255 PM CST Sat Dec 8 2018 High pressure was centered near southern Michigan with a ridge extending well northwest into the Wisconsin and Minnesota this afternoon. Despite a dry air mass and the high, stratus was moving north through the Northland. Much of the guidance was doing a poor job depicting this cloud but we leaned toward the RAP although adjusted timing to bring the cloud in faster. Fog will occur as well and we added that into Sunday. Temperatures will be quite variable tonight with any areas that take longer to cloud over or that develop breaks will be much colder. We have lows from 10 to 15 but will have to adjust based on short term satellite trends. There was a back edge to the stratus over southern Minnesota but we expect that to slow tonight, perhaps working into southern parts of our area overnight. The stratus was at least partially driven by warm air advection. The warm air advection will bring in 850mb temperatures from 0 to 2C by Sunday afternoon and will serve to further strengthen the inversion. We do decrease cloud cover through the day Sunday but confidence is not very high, especially over much of northern Minnesota. We have highs in the upper teens to mid twenties. .LONG TERM...(Sunday night through Saturday) Issued at 255 PM CST Sat Dec 8 2018 The period will feature high temperatures near or a few degrees above normal and a few opportunities for light snow. A few shortwaves will move through the region from Tuesday night through Friday bringing chances for light snow with minimal accumulation. The shortwave Tuesday night/Wednesday will be weak with little significant moisture and we have low POPs and not even in all areas. A stronger shortwave will arrive Thursday and depart Friday but again we only expect light snow amounts. An upper level ridge will build in later Friday and remain over the region into Saturday. High temperatures will be near or a few degrees above normal and overnight lows are expected to be quite a bit above normal Tuesday night through Friday night. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 532 PM CST Sat Dec 8 2018 Large area of IFR stratus under strong inversion will linger through the night while advecting around. Could not see a reason to improve any site to VFR before morning. Models not handling the stratus very well, so a lower confidence forecast particularly on timing of flight cats. && .MARINE... Issued at 939 PM CST Sat Dec 8 2018 West to southwest winds will continue overnight as a sharp pressure gradient noses into the region. Expanded the Small Craft Advisory to all zones except the far western Lake Superior zones. The wind will slowly decrease Sunday from west to east but it will take the waves a bit longer to diminish. && .PRELIMINARY POINT TEMPS/POPS... DLH 14 23 13 26 / 0 0 0 0 INL 10 21 8 25 / 0 0 0 0 BRD 13 24 11 29 / 0 0 0 0 HYR 14 26 12 26 / 0 0 0 0 ASX 15 27 16 29 / 0 0 0 0 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...Small Craft Advisory until 4 PM CST Sunday for LSZ121-146>148. Small Craft Advisory until 10 AM CST Sunday for LSZ140>143. && $$ SHORT TERM...Melde LONG TERM...Melde AVIATION...Wolfe MARINE...Wolfe
Area Forecast Discussion
National Weather Service Hastings NE
514 PM CST Sat Dec 8 2018 .SHORT TERM...(This evening through Sunday) Issued at 340 PM CST Sat Dec 8 2018 No major concerns in the short term as dry conditions continue. Water vapor and upper air analysis indicates a fairly complex/convoluted upper pattern with several disturbances of note. The largest/most impactful disturbance is located across the S. Plains and will shift E well away from our area. Another potent/compact vort max was located over the N. Plains. Finally, a third (weaker) disturbance was located over the Intermountain West near SLC. The latter two disturbances will combine to carve out a new trough over the Central Plains tonight and into Sun, but the impact to sensible wx will be limited due to meager moisture left behind the initial S. Plains system. The main impact to local wx will be a wind shift tonight, though some models are showing fog potential as well. The NAM (and associated hi-res NAMNest, ARW, and NMM) along w/ SREF are most aggressive with fog development, though feel this is overdone. There is only limited support from the HRRR, RAP and MET/MAV guidance and relegated to mainly the far W CWA. Will insert patchy fog per coordination w/ neighbors to W/SW, but feel the veering winds at 4-8kt will be enough to preclude repeat of last night. For Sunday, no big changes to the forecast. Increased cld cover in morning to account for high level cloudiness associated with disturbance pinwheeling S across the CWA. The system is actually fairly strong in the upper levels, but as mentioned above, moisture is extremely lacking in the low-mid levels. Thus, no precipitation is expected. Models tweaked high temps up a bit for Sun aftn, which is plausible given deep W/WNW downsloping flow in low-mid levels, but didn`t go drastically higher given some high cloudiness and modest CAA to help offset downsloping effects. .LONG TERM...(Sunday night through Saturday) Issued at 340 PM CST Sat Dec 8 2018 The main story for the extended will be a modest, gradual warmup through midweek then the POTENTIAL for a system & wintry precipitation mid-late next week. We`ll start off the week on a quiet note as un upper level trough initially over the Central Plains Sun night quickly opens up and shifts E to the SE CONUS Mon AM. In its wake, we`ll see shortwave ridging/subtle height rises Mon PM into Tue. Highs Mon will range from low 30s to low 40s. Temps warm some for Tue with highs mid 30s to upper 40s. Warmest readings both days will favor areas with little to no snow cover (S and SE CWA). However, these readings along with periods of sunshine should be enough to erode some of the snow cover we still have. A weak, open and moisture starved northern stream system will quickly move W to E across the Central/N. Plains Tue night into Wed. Pcpn chcs remain very low with this system and since it is of Pacific origin, there is not a lot of cold air either. In fact, there is little change in temps from Tue into Wed. The forecast becomes a little more interesting for the second half of next week. While all models show at least some sort of disturbance passing thru late Wed night thru Thu night, there are considerable differences amongst the models in terms of strength, track and timing. The GFS is the fastest/weakest solution (glancing lgt pcpn S/SE CWA), and the latest Canadian run is by far the strongest/slowest/furthest N solution (shows significant pcpn for much of CWA). The EC is somewhat in the middle of the road in terms of timing and eventually strengthens system similarly to Canadian, but it is much further S (mainly dry for CWA). Neither the GFS or EC presents much potential for pcpn for CWA, so the Canadian is clear outlier. After extensive coordination with other NWS offices across the region, felt it was prudent to cap POPs around 50 percent on Thu, then go with a dry forecast Thu night thru Fri night despite the blend (which takes Canadian model into account) giving extensive 30-50 POPs that entire time frame. Plenty of time to work out details, obviously, but wanted to avoid painting entire time frame with POPs when really only one run of one model was showing that sort of potential. Otherwise, temps should be near to slightly below normal for the latter portions of next week. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday) Issued at 508 PM CST Sat Dec 8 2018 VFR conditions are expected through this TAF period. There is an outside chance for some patchy fog to develop tonight, although short-term models models continue to show the best potential west of the terminals. Therefore, I don`t foresee any impact at this time. Any fog that does develop in the vicinity will also be short- lived as winds become westerly to northwesterly by sunrise on Sunday. Otherwise just expect scattered high clouds tonight into Sunday morning. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ SHORT TERM...Thies LONG TERM...Thies AVIATION...Mangels
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
957 PM EST Sat Dec 8 2018 .SYNOPSIS... With cold Canadian high pressure to our north and low pressure passing to our south, we are having a major winter storm. The low pressure moves off the Carolina coast Sunday evening taking most of the wintry weather with it. The last of the light precipitation finally ends Monday night when the upper trough passes. Cool high pressure will be in control Tuesday and Wednesday, then the next storm system arrives at the end of the week. && .NEAR TERM /THROUGH SUNDAY/... As of 930 PM EST: No significant changes to the forecast as of mid- evening. Caught a nice radar bright band strung out west to east across the nrn Upstate earlier this evening, which essentially marked the transition zone between the rain with some sleet across the srn 2/3 of metro GSP, and the mostly snow across nrn Greenville and nrn Spartanburg counties. That boundary has since drifted north toward the NC state line. Meanwhile...the northern extent of the light precip can`t seem to make it into the nrn foothills and nw Piedmont, which is only allowing temps up in that region to cool off this evening, which means lower wet bulb temps, which means even more certainty that precip will either start as snow or quickly change to snow in the I-40 corridor east of the mtns later tonite. We await more guidance before applying any mid-course corrections. Otherwise, a 1013 mb surface low center was analyzed over southeast Louisiana this afternoon, while water vapor imagery and RAP upper- level initializations reveal a vigorous southern stream wave over east Texas. There is good model agreement on the eastward evolution of these features, but subtle, yet important differences exist with regard to the thermal profiles. The 500 mb low over east TX will lift northeast over the MS River Valley tonight and then across the Appalachians on Sunday. Meanwhile, the surface low center is expected to move across southern GA tonight and then exit the southeast coast by midday Sunday. Mid-level frontogenetical forcing over the baroclinic zone draped over our region this afternoon will give way to robust deep forcing overnight. These mechanisms will come together atop the western Carolinas and northeast Georgia in the form of strong, deep-layer Q-vector convergence ahead of the main wave, strong right entrance region upper jetlet divergence, and improving isentropic lift and upslope in the stout southeasterly or easterly 850 mb flow. The best forcing and deepest moisture will arrive just as 850 mb temperatures cool rapidly from north to south circa 06Z-12Z. A blend of cooler GFS and warmer NAM profiles were used for this period. The 850 mb low center track through the SC midlands/piedmont will be very favorable for heavy snow across the southern Appalachians and adjacent NC foothills. In addition, the very classic and deep cold air damming east of the Appalachians will drive freezing or near freezing surface temperatures nearly through the southern piedmont to permit freezing rain and icing to mix in at times. All told, the warnings, advisories, and amounts still look reasonable with predominantly snow across most of the mountains and foothills, a broader sleet band developing early Sunday morning, with freezing rain making the best southern tier appearance by daybreak Sunday. As the 850 mb low pivots off to the southeast early Sunday, thicknesses will cool once again to lead to more dominant snow/sleet returning from the north. This transition is complicated by some mid and upper level drying wrapping in from the southwest Sunday afternoon. There is some potential for more freezing drizzle and light freezing rain in these dry pockets where ice nuclei are unavailable, but the moisture in the profiles is quite uncertain and continued forcing west of the surface low could lead to some ice nucleation. Will thus stick to the top-down hydrometeor ptype approach through the duration of the event with the assumption that ice nuclei exist. At any rate, precipitation rates will experience a lull Sunday afternoon and early evening as the better forcing moves east for most areas. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... As of 215 PM Saturday: The weakening phase of CAD will begin Sunday night, with both the low pressure and the parent high having drifted east off the Atlantic coast. The low to midlevel flow over the wedge airmass will have backed somewhat, but still driving reasonably strong WAA into the western Carolinas. The depicted 500mb pattern is complex, with an ill-defined shortwave and vort max slowly moving over our CWFA from the west. As the CAD-associated forcing diminishes, the shortwave will make up for it to some degree. Accordingly, 850mb heights recover little in the wake of the sfc low. The warm advection is expected to maintain sufficiently warm temps in the midlevels that a change from rain to a wintry mix will occur over a portion of the Piedmont overnight, with precip rates likely to pick up again early Monday. Moisture becomes increasingly shallow as a new area of continental high pressure exerts increasing influence, but our remaining PoPs will be bolstered by upper divergence and/or deformation occurring with another cutoff shortwave diving into the Deep South on Monday. As this feature moves south of the area Monday night and subsidence/drying continue, we finally are able to let PoPs drop below slight-chance. Sfc temps in this period are perhaps the least confident part of the fcst. The expectation that heavy snow/ice cover will be present over most of the area implies we should continue to favor the colder guidance into Monday. The higher resolution members, such as the NAMNest and HiRes windows, seem to show the wedge weakening enough to allow some warming over the Piedmont, and becoming shallow enough for temps to warm appreciably Sunday night in the higher elevations along the Blue Ridge, plus a portion of the Savannah River Valley. For now these sources have been minimized in the fcst, but guidance still supports enough warming for wintry precip to change to rain over some areas. Additional accumulation after 00z Mon is not expected to be significant compared to what falls prior to that time. Monday`s highs will be high enough to support some partial melting, though with generally mostly cloudy or overcast skies it likely won`t reduce snow/ice pack very much. Roadways are likely to become wet and with much colder temps still expected Monday night, black ice will be widespread around the region. After the end of the Winter Storm Warning we likely will need to issue an Advisory to cover the black ice threat through early Tuesday. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 235 PM EST Saturday: The guidance agrees an a very energetic storm system affecting the area next weekend. However, there are some significant differences in the details. Before then, expect dry and cold high pressure for Wednesday. Lows will be 10 to 15 degrees below normal with highs 5 to 10 degrees below normal. The high will remain ridged in place across the area Thursday in a cold air damming pattern. The center of the high is progressive so this will not be classical damming. Moisture begins to increase ahead of the next weather system with weak isentropic upglide as well. Small rain chances will develop during the day. Lows will range from near normal to 5 degrees below normal with highs around 10 degrees below normal. If the precip starts early enough, then some would fall as snow before warming begins. However, the chance of any accums is near zero. As mentioned above, the guidance agrees that a strong upper low forms in a deep trough over the central CONUS on Friday. The GFS and Canadian are farther north and faster than the ECMWF. The GFS has the upper low moving into the TN valley Friday and to the mid- Atlantic on Saturday. The ECMWF has the low moving to near Mobile Friday and to central GA on Saturday. The GFS swings an occluding front across the area Friday with the occluded low moving east across VA Saturday. The ECMWF has the occluding low passing by to our south in Miller-A fashion. Both models have good in-situ damming forming but are still relatively warm keeping the precip liquid Friday. The GFS is very dynamic with strong shear and helicity developing. There is some elevated instability ahead of the front across the I-77 corridor. The ECWMF has little to no instability. The GFS shows a long period of NW flow snow developing with some snow showers breaking containment across the NC foothills and piedmont. The ECMWF would suggest snow showers across much of the area with the farther south low. Given the big change in the ECMWF forecast, have trended toward the GFS solution with low confidence. That said, it does look like Friday will be wet either way, so have likely PoP for that period. Kept thunder out for now. Have highs warming above normal for Friday and cooling to near normal for Saturday. Lows will be above normal both mornings. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... At KCLT and Elsewhere: Damming continues to build in with precip overspreading the area. PL reported at KCLT at 23z, it`s been snowing for a while at KAVL, and precip hasn`t gotten to KHKY just yet; still all rain in the Upstate but the cooling temps are slowly working south. Expect a mess of wintry precip across the area, with KGMU/KGSP/KCLT seeing the most mix, while KAVL/KHKY should see mostly -SN. KAND mostly -RA with some -FZRA or PL mixing in in the morning. Cigs will vary between LIFR and low MVFR through the period, with vsbys sometimes <1/2SM in the heavier SN. Should see some increasing gusts across the Piedmont TAFs tomorrow morning as well, and have introduced LLWS at KAVL per latest guidance. Precip rates will diminish Sunday afternoon but incredibly messy until then. Outlook: The winter storm will linger late Sunday through Monday, with plenty of wintry ptypes and low restrictions. Snow showers may get reinforced from the west Monday as an upper disturbance arrives from the west. Significant improvement is not expected until Tuesday. Confidence Table... 03-09Z 09-15Z 15-21Z 21-00Z KCLT Med 72% Med 64% Med 78% High 100% KGSP Med 75% Low 58% High 91% High 91% KAVL Low 56% Med 75% High 86% High 100% KHKY Med 78% Med 69% Low 58% High 100% KGMU Med 77% Low 58% High 91% High 100% KAND Med 78% Med 75% High 100% High 100% The percentage reflects the number of guidance members agreeing with the scheduled TAF issuance flight rule category. Complete hourly experimental aviation forecast consistency tables and ensemble forecasts are available at the following link: && .GSP WATCHES/WARNINGS/ADVISORIES... GA...Winter Storm Warning until noon EST Monday for GAZ010-017. Winter Storm Warning from 1 AM Sunday to noon EST Monday for GAZ018. Winter Weather Advisory from 1 AM Sunday to noon EST Monday for GAZ026-028-029. NC...Winter Storm Warning until noon EST Monday for NCZ033-035>037- 048>053-056>059-062>065-068>072-082-501>510. SC...Winter Storm Warning until noon EST Monday for SCZ001>003- 005>009. Winter Storm Warning from 1 AM Sunday to noon EST Monday for SCZ004-010-012>014. Winter Weather Advisory from 1 AM Sunday to noon EST Monday for SCZ011-019. && $$ SYNOPSIS...DEO NEAR TERM...HG/PM/TDP SHORT TERM...Wimberley LONG TERM...RWH AVIATION...TDP
Area Forecast Discussion...cor
National Weather Service Wilmington NC
912 PM EST Sat Dec 8 2018 .SYNOPSIS... A strong low pressure system moving across the Gulf states will strengthen and send a surface low offshore of Savannah Georgia Sunday morning, passing by Cape Fear late Sunday afternoon. Periods of rain, wind, and daytime temperatures below normal, can all be expected through at least Tuesday, as the entire low pressure complex clears the Carolinas. Mild high pressure will bring drying and warming into late week. && .NEAR TERM /THROUGH SUNDAY/... As of 900 PM Saturday...Just a quick update to add immediate coastal SC counties to the Wind Advisory. HRRR soundings coming in showing a solid 30-35 kt sustained winds in the 1000-1500 ft layer with 45-50kt at 2000 and 2500 ft, respectively. Granted, these heights are in the layer that is thermally strongly inverted and thus relatively stable to vertical thermal mixing it is more than plausible for the rainfall to reach sufficient intensity to overcome said stability and mix those momentum levels to the ground. As of 730 PM Saturday...Forecast holding, temperatures nearly on the mark, all liquid falling, chilly liquid. No changes were needed, but will take a second look at 00z data sets regarding winds along the SC coast on Sunday, presently, just below advisory criteria. Rain rates across NE SC and SE NC 0.07" per hour or less, so not flood threat anytime soon. A few moderate rain pockets could introduce brief ponding and a hydroplaning danger on high speed thoroughfares overnight. Most hourly temperature guidance showing leveled-off temps overnight or dropping a few degrees. As of 315 PM Saturday...Overrunning, ie. Isentropic lift, will initially be the primary cause of the pcpn across the FA this aftn into this evening. Later this evening and overnight, the old frontal boundary will be lifting northward as a warm front and by daybreak Sun, it will extend ENE over the Atlantic waters from the sfc low progged over coastal Georgia. In addition to overrunning, the FA will have dynamics from mid- level s/w trof(s) to further enhance the pcpn across the FA. At this point do not expect any pcpn type issues across the FA. Not enough cold air will make it to the FA prior and during this Pcpn Event and although the warm front is progged to stay over the Atlantic waters, it`s close proximity will produce NE to ENE winds in the low levels, enough to tap those mild SSTS. Have indicated, the heaviest rain occurring from late in the pre-dawn Sun hrs thru late daytime morning Sun which corresponds to the closest approach of the sfc low as it tracks NE over the Atlantic waters parallel to the Carolina coastlines, reaching the offshore waters SE of Cape lookout by sunset. It`s during Sun when the best deepening phase will occur and as a result, a tightening of the sfc pg. Winds along the immediate ILM NC Coast will flirt with Wind advisory criteria in gusts during this deepening phase and will go ahead and raise one for the coastal zones from Surf City To Cape Fear which includes Bald Head Island. The rainfall amounts will remain under FFA criteria but unfortunately will lead to additional and revised upwards to various River Flood Warnings across the FA. Ie. The Lumber River at Lumberton progged to reach Moderate Flood Stage. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 315 PM Saturday...The mid levels will feature a cutoff low forming across the Tennessee Valley which kinda morphs into an east/west mid level trough Monday before being kicked to the east by Tuesday morning. At the surface there will be a broad but not necessarily frigid northeasterly flow with low pressure offshore and high pressure well to the west. Really there is no well defined forcing mechanisms around with the mid level as the models show the mid level feature developing weak precipitation along the trough axis in what essentially appears to be dynamically driven moisture. The deeper moisture will have long since exited the area. Basically continued to advertise chance pops with an overall trend downward through the period. There remains a small risk of a brief period of freezing precipitation late in the period but moisture will be all gone as temperatures become conducive. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 315 PM Saturday...A fairly progressive mid level pattern will develop across the U.S at least briefly. Mid level ridging and modified surface high pressure will bring dry and reasonably warm conditions for mid week moreso on Wednesday and Thursday. Tuesday still looks be a little on the dreary side as mid level and surface low pressure move off to the east slowly. Highs both Wednesday and Thursday could approach 60 in some areas which is just about normal for this time of year. The main focus of the extended period arrives late in the week in the form of closed low pressure at the mid levels moving across the Tennessee Valley. Plenty of moisture associated with this system as it slowly progresses eastward for next weekend. Raised pops incrementally to address some increase in confidence with this system. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... As of 00Z...Cigs dropping at KFLO currently and confidence is high IFR will spread to the remaining terminals this evening. Vsbys should remain MVFR in light to moderate rain. Northeast winds will increase overnight gusting to 25-30 kt, highest at the coastal terminals. IFR likely to persist through tomorrow. There is a chance for non-convective LLWS between 12Z and 17Z tomorrow morning at coastal sites with winds at 2000 ft between 45 and 50 knots, but strong forecasted surface winds and low confidence have kept mention out of TAFs for now. Extended Outlook...Low pressure system will lead to MVFR/IFR/rain Saturday through Monday. Clearing Tuesday. VFR Wednesday and Thursday. && .MARINE... NEAR TERM /THROUGH SUNDAY/... As of 315 PM Saturday...Solid Gale Warning to remain in effect for all waters this period. During the closest approach of the intensifying fcst low, the area waters could see gusts pushing 40 to 45 kt from early Sun morning thru early to mid-afternoon Sun. Storm Force gusts will likely occur over the adjacent offshore waters depending on the intensity of the low. With the frontal boundary remaining over the offshore waters, wind directions will 1st veer from NE to ENE tonight thru early Sun. As the low passes by the area waters during Sun, winds will back to N to NNE directions. Significant seas will build rather quickly during the next 12 hours and peak in double digits across the waters extending from 10 to 20 nm out late tonight thru much of Sunday. The exception will be from South of Cape Fear to Little River Inlet where seas will be lower, especially near shore, due to NE winds being an offshore trajectory for these waters. Seas will primarily be composed of wind driven waves with not much, if any, swell component added on. SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 315 PM Saturday...Gale conditions will continue for a few hours as the gradient is slow to subside with slow moving low pressure offshore. Anticipate small craft conditions through the remainder of the period with northeast winds either side of 20 knots. Significant seas will relax a bit from the earlier gale forced values but remain well into small craft criteria, with a still healthy 5-8 feet by Tuesday morning. LONG TERM /TUESDAY THROUGH THURSDAY/... As of 315 PM Saturday...Expect a northerly component to the winds most of the period as high pressure moves west to east across the northern Gulf of Mexico. A return flow may develop late Thursday as the next storm system develops in the Tennessee/Mississippi Valley. Elements may warrant a continuation of a small craft advisory Tuesday but should diminish enough to be headline free the other days. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...Wind Advisory from 6 AM to 6 PM EST Sunday for SCZ054-056. NC...Wind Advisory from 6 AM to 6 PM EST Sunday for NCZ106-108-110. MARINE...Gale Warning until 10 PM EST Sunday for AMZ250-252-254-256. && $$ SYNOPSIS...MJC NEAR TERM...DCH/MJC/MBB SHORT TERM...SHK LONG TERM...SHK AVIATION...MRR
Area Forecast Discussion
National Weather Service Lincoln IL
845 PM CST Sat Dec 8 2018 .UPDATE... Issued at 845 PM CST Sat Dec 8 2018 An elongated axis of surface high pressure will continue to extend across northern IL tonight, providing for winds ranging from light and variable for some areas north of the Illinois River to a light northeast wind elsewhere. Nearer to the high pressure axis, some diurnal cloud cover is slowly dissipating, but may be replaced by patchy fog late in the night as radiational cooling increases. Afternoon forecast package had patchy fog mainly in Knox, Stark and Marshall counties, and this still looks about right. Lows should range from the mid teens over most of central IL, to around 20 south of I-70. Otherwise, have made some minor adjustments to cloud cover with the evening update. && .SHORT TERM...(This evening through Sunday) ISSUED AT 318 PM CST Sat Dec 8 2018 20z/2pm surface analysis shows a sprawling area of high pressure over the southern Great Lakes...while a 1012mb low tracks across southern Louisiana. The high will continue to suppress the southern-stream system along the Gulf Coast through Sunday: however, high clouds will stream as far north as southeast Illinois. Latest satellite imagery continues to show the high clouds across the E/SE, with lower diurnal clouds primarily along/north of I-74 into northern Illinois. Think these will largely erode toward sunset, but the HRRR hints at re-development overnight as the boundary layer flow becomes E/NE. Have therefore gone with mostly cloudy wording along the northern periphery of the KILX CWA tonight, with partly to mostly clear conditions elsewhere. With clear skies and light winds, radiational cooling over the light snow pack will allow lows to drop into the lower teens across the heart of central Illinois...with lower 20s south of I-70 where a thick blanket of high clouds will persist. May see some fog development late tonight as well...particularly northwest of the Illinois River near Macomb and Galesburg. Any fog will burn off by mid-morning, followed by mostly sunny and cool conditions on Sunday with high temperatures in the lower to middle 30s. .LONG TERM...(Sunday night through Saturday) ISSUED AT 318 PM CST Sat Dec 8 2018 High pressure will drift east of the region early next week, allowing a southerly return flow to bring a gradual warming trend to central Illinois. High temperatures will remain in the middle to upper 30s on Monday, but will rise into the 40s Tuesday through Saturday. The next significant chance for precipitation will hold off until Wednesday when a weak disturbance brings a chance for rain showers. After that, a stronger system will impact the region by the end of the week. 12z Dec 8 models are in poor agreement with the track of this feature, as well as the associated thermal profile. With surface temps reaching the 40s, it appears mostly rain can be expected on Thursday into Friday: however, snow will be possible on the back side of the departing low Friday night. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 548 PM CST Sat Dec 8 2018 An area of MVFR cigs is expected to affect areas from around KPIA-KCMI northward this evening as an expansive diurnal cloud shield slowly dissipates. Current trends suggest KCMI will stay just south of the edge of these clouds, while KBMI and KPIA may stay in it for a few to several hours. Otherwise, conditions will be SKC-SCT250. Winds E-NE 5-10 kts through the period. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...37 SHORT TERM...Barnes LONG TERM...Barnes AVIATION...37
National Weather Service Jackson KY
930 PM EST Sat Dec 8 2018 .UPDATE... Issued at 930 PM EST SAT DEC 8 2018 Forecast still mainly on track at this early stage, and have not made any substantive changes. Blended obs into the forecast, and made some minor temperature revisions for tonight based on 18Z runs. The 18Z runs still showed large differences between the NAM and GFS for overnight and Sunday, with the NAM being colder and wetter. There are model differences in the handling of a mid level speed max over the TN Valley and southern Appalachians tonight, and also low level flow over southeast KY late tonight into Sunday, with the GFS showing more isentropic downglide around 850 mb. Low level differences could be partially due to handling of cold air damming and terrain influence to our east. Will see what 00Z runs look like. QPF differences for our area become a factor already during the overnight hours, and continue into Sunday. If the GFS were to trend toward the NAM, or it became apparent that the NAM was verifying better early on, winter wx would be more significant for our area and forecast changes would be needed. && .SHORT TERM...(This evening through Sunday night) Issued at 434 PM EST SAT DEC 8 2018 The winter storm is set to begin impacting the region overnight. However, instead of continuing the southward trend with this system, 12Z model runs all began shifting farther north again. Furthermore, they actually starting moving away from continuity with vast differences in their solutions for precip types and amounts across the CWA. The ECMWF and NAM became much more robust with QPF, while the GFS remained more conservative...ironically this is the complete opposite of ongoing trends several days ago. The HRRR, the GFS and the RAP are much warmer, with a good possibility that hydrometeors could melt and end up falling as rain. The NAM and ECMWF show the potential for a shallow warm nose, so while they have the highest QPF, you can`t rule out some mixed precip, especially during onset. To caveat this, air temperatures today, especially in the southern CWA, rose into the upper 30s. With cloudy skies and easterly winds, these temperatures are not expected to quickly drop off during the evening. Even if snow is able to melt in the warm nose and then fall back into a cold near-surface layer as freezing rain, the surface temperatures will likely lag by several hours before falling below freezing, helping to mitigate much of the accumulating ice concerns. However, did keep with mention that a glaze of ice could be possible in the hazard products. It may actually be very possible that the best ice totals will be in the highest terrain, due to the face that they were quite a bit cooler today and will spend much of the night below freezing, while being at a high enough elevation to cut into the warm nose of the precipitation causing any melting precip to hit the ground before having a change to refreeze. On that note, the highest terrain will also have the best potential to accumulate snowfall. Overall, this is a very very tricky forecast, and it is unlikely that any one model is correct, or that the forecast is correct for every location. However, tried to do the best to trend the forecast farther north and find a happy medium between the current models, WPC, and the neighboring offices. It is in somewhat high confidence that the precip will be shifting east of the region by Sunday evening/Sunday night. In it`s wake, the latest forecast snow totals include a dusting to around an inch across the central portion of the CWA, 1 to 3 inches in a swatch stretching from the SW portion of the CWA to central/northern Pike County. The counties near the VA border could range from 3 to 5 inches, with locally higher amounts possible in the high terrain. Once again, it is entirely possible that totals could range from 5 inches on the peaks to almost no snow in the valleys depending on how the temperature/moisture profile pan out. Any snow that does fall will be heavy and wet, with impressively low snow ratios being one of the few things that has remained constant through this forecast. Snow of this nature can cause major impacts even for small amounts, creating slushy, slick and treacherous road conditions, as well as adding weight onto trees which could lead them to break and possibly down power lines. Based on the latest snowfall forecast, went ahead and upgraded counties along the VA border to a Winter Storm Warning. Even if the valley locations see less snow compared to the higher elevations, there will likely still be impacts related to the heavy wet nature of the snow. Kept the remaining counties within an advisory with 1 to 3 inches forecast. Since the models are trending farther north, also added another tier of counties northward to the advisory, including Rockcastle, Jackson, Owsley and Breathitt, where snow totals have increased to between 1 and 2 inches and impacts are likely. .LONG TERM...(Monday through Saturday) Issued at 444 PM EST SAT DEC 8 2018 The models are in good agreement with an amplified long wave pattern to continue across the CONUS through the period. High pressure will work in across the Ohio and Tennessee valleys through the middle of next week, bringing dry weather. Another deep system will then take shape across the central CONUS by Thursday, eventually bringing a period of unsettled weather across eastern Kentucky as we close out the work week and head into the weekend. There is much uncertainty with details on the evolution with this storm system, and have generally favored slower timing, given the amplitude. Clouds will be on the decrease on Monday, as high pressure builds in from the west. Temperatures will average below normal early next week, with highs in the low 40s and lows in the teens and 20s. Tuesday morning looks to be the coolest morning. By the middle of the week, high pressure will shift off to our east, with return flow ensuing. This will lead to some ridge/valley temperature splits at night, and have gone purposely cooler in our eastern valleys. Again, have favored a slower solution with the deeper system to impact the area Thursday through Saturday, reserving the higher PoPs from Friday into Saturday. Temperatures will trend above normal through Thursday and Friday, with highs back in the 50s. Readings will then cool off to near normal by Saturday. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 700 PM EST SAT DEC 8 2018 VFR conditions and winds less than 10 kts still prevailed at TAF issuance. However, that will change during the night. As precipitation develops northward into the area, ceilings and visibility will lower. Sub-VFR conditions should arrive near the TN border around 06Z, and reach their northward extent near the Mountain Parkway late Sunday morning. Much of the area south of a line from around KSME to KPBX is expecting a deterioration to IFR during this time frame. Improvement is forecast from northwest to southeast on Sunday afternoon, but locations near the TN and VA borders will likely not climb above MVFR before the end of the period. In terms of precipitation, a mixed bag of wintery weather is possible, but the majority is expected to be snow and rain. The precipitation could be heavy at times, especially near the TN and VA borders. Precipitation amounts and intensity will taper off with the northward extent, and little if any precipitation is expected north of the Mountain Parkway. Winds during the period will remain generally below 10 kts and out of the northeast. && .JKL WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 7 PM EST Sunday for KYZ087-088-118- 120. Winter Weather Advisory until 7 PM EST Sunday for KYZ068-069-079- 080-110-112>117. Winter Weather Advisory until 7 PM EST Sunday for KYZ083>086. && $$ UPDATE...HAL SHORT TERM...JMW LONG TERM...GEOGERIAN AVIATION...HAL
Area Forecast Discussion...UPDATED
National Weather Service Lubbock TX
811 PM CST Sat Dec 8 2018 .UPDATE... Several reports have been received of dense freezing fog in and around the Lubbock area. The fog does not show up on satellite yet at the moment because this fog is likely less than 10m thick. The HRRR certainly has the best handle on this fog and should expand over the next several hours favoring the snow covered areas. && .PREV DISCUSSION... /issued 523 PM CST Sat Dec 8 2018/ AVIATION... Snow cover in place providing abundant moisture will allow for freezing fog to develop later this evening lasting until mid morning on Sunday. KLBB is most likely to experience this with the deepest snow depth around that terminal. Lesser chances will exist at KPVW with less snow depth. PREV DISCUSSION... /issued 150 PM CST Sat Dec 8 2018/ DISCUSSION... Our winter storm has now pushed east of the region. Only a few little snow showers remain across the eastern half of the forecast area while out west clearing skies have pushed in from New Mexico. Skies are expected to clear this evening, but that will lead to additional issues, especially in the snow-covered parts of the forecast area. The combination of snowpack and clear skies will result in rapid cooling having the effect of refreezing moisture on area roadways and the likely development of some freezing fog and stratus. Some of the fog could become dense, something that will be monitored as the evening progresses. The remainder of the forecast remains relatively quiet. Models continue to hold onto a progressive pattern with a long-wave trough over much of the CONUS through the upcoming week. Short- wave ridging is still on track to cross the region Tuesday followed quickly by southwesterly mid and upper flow. These two days with their westerly low level component will result in the warmest days of the week. Finally, another upper level short-wave trough will approach the region, this time from the northwest. There is still some hint that this trough could bring a brief shot of rain showers Thursday. Will maintain slight chance wording for that day with this forecast. && .LUB WATCHES/WARNINGS/ADVISORIES... Freezing Fog Advisory until 10 AM CST Sunday for TXZ027>030- 033>036-039>042. && $$ 01
Area Forecast Discussion
National Weather Service Paducah KY
622 PM CST Sat Dec 8 2018 .UPDATE... Issued at 619 PM CST Sat Dec 8 2018 For aviation section. && .SHORT TERM...(THIS EVENING THROUGH Monday NIGHT) ISSUED AT 230 PM CST SAT DEC 8 2018 No major changes expected for the advisory area for tonight. Models are struggling with the dry air from high pressure centered over Indiana this afternoon. HRRR and most other models continue to push precipitation northward, but progress is slow. Have had reports along our southern border of snow and some sleet. On the larger scale, radar returns are drying up in northwest Arkansas, but should return to that area and our southern border late this evening as the upper low tracks east into central Tennessee by 12z Sunday. I have trimmed the northern PoPs from CONSHORT for tonight based upon current trends. May still be too far north. Precipitation should generally be snow/sleet this evening then transition to more of a mix of snow, sleet and freezing rain. The system should depart the area around daybreak. Snowfall amounts look to be 1 inch or less and any ice generally less than 1/10 of an inch. The combination may cause some issues traveling so will keep the advisory going. Model soundings vary by model, of course. Dry air near the surface will gradually be overcome during the evening over the extreme southern sections. A warm nose develops this evening with warm advection at 925 over the HOP area. This will help to create a variety of precipitation types. However, the precipitation is expected to be generally light. As this system moves east, high pressure will keep the area dry through early Tuesday. Optimistic sky forecast to actually see some sun. .LONG TERM...(Tuesday THROUGH Saturday) ISSUED AT 230 PM CST SAT DEC 8 2018 The medium range models were in reasonable agreement, for the most part, in the extended forecast period. Tue/Tue night should be the beginning of a modest warming trend for us under ridging aloft and a developing westerly to southwesterly low level flow. Most model solutions suggest that by Wed, measurable pcpn is possible by the evening, as it may take all day for the lower troposphere to moisten up. The source of energy for this minor rain event will be mid level shortwave energy embedded in the quasi-zonal flow over the country`s midsection. Just behind this feature, the models continue to advertise a dynamic low pressure system digging/deepening through the southern Plains, though the 12Z ECMWF showed a much more southerly path of this low, moving into the Deep South by Fri. Most model solutions suggested that the dynamic low will be stacked or nearly so by then as it continues moving eastward, and eventually into the eastern Great Lakes region (most models). The ensemble means tended to suggest the more northerly track possibility. A slightly modified initialization blend suggests PoPs for generally light amounts of rain will steadily ramp up in the warm advection pattern ahead of this system Wed night and Thu. At this time, forecast high precipitable water values, the apparent slow movement of this system, and robust Gulf moist advection will promote heavy rain potential primarily Thu night and into the daylight hours Fri. For now, we will go with 1-2 inches of total rainfall. The system should continue to move away to the east on Fri, possibly leaving Sat mostly dry. Lighting is a possibility, but not a certainty. It is dependent on where the surface low will be, the location of which is vague at this time. It was left out of the forecast for now. What is more certain is that the latter half of next week will be wet at some point. && .AVIATION... ISSUED AT 620 PM CST SAT DEC 8 2018 Relatively calm on the north side of the storm system moving through the southern states. All TAF sites VFR through the period. Only precipitation/ceiling issues will be confined to the southern borders of Missouri and Kentucky where MVFR conditions possible 06z-12z. Light FZRA/IP also seem a good possibility along/just north of the AR and TN borders. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...Winter Weather Advisory until 6 AM CST Sunday for MOZ108>110-112- 114. IN...None. KY...Winter Weather Advisory until 6 AM CST Sunday for KYZ001-002-006- 009-012-017-022. && $$ UPDATE...GM SHORT TERM...PS LONG TERM...DB AVIATION...PS