Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/18/19

Area Forecast Discussion
National Weather Service Green Bay WI
620 PM CST Sun Nov 17 2019 Updated aviation portion for 00Z TAF issuance .SHORT TERM...Tonight and Monday Issued at 251 PM CST Sun Nov 17 2019 The latest RAP analysis and satellite/radar imagery show an upper trough moving across the northern Mississippi Valley early this afternoon. This trough is pushing an occluded front across Wisconsin, with areas of light precip occurring along the front. After receiving 1 to 3 inches over parts of north-central WI this morning, most of the light precip, including snowfall, has been diminishing across the region. Patchy drizzle and freezing drizzle have been showing up at times on area radars and surface obs over northwest/north-central WI as mid-level moisture departs. Because of previous snowfall and road temps above freezing, don`t think freezing drizzle will have much impact through the afternoon. Another area of rain is surging northeast over southern WI, and should move into east-central WI later this afternoon. Looking further west, widespread low overcast prevails all the way to the eastern Dakotas. As the front continues to move east across the area, forecast concerns revolve around potential for freezing drizzle/mist followed by cloud cover. Tonight...The front will slowly move east across north-central WI in the evening and northeast WI overnight. Steady light rain, possibly mixed with snow, will depart east-central WI early this evening. But forecast soundings indicate that the surface to 800mb layer will remain saturated along the front, so think potential for drizzle and freezing drizzle will persist through much of the evening. With cooling temperatures and loss of solar insolation, the freezing drizzle may cause slippery spots may develop on untreated roadways. Any wet roads may also develop some black ice as temps fall below freezing. Otherwise, expect a low overcast cloud deck to persist through the night, with not much of a fall of temperatures. Lows ranging from the middle 20s to the low 30s. Monday...Widespread low clouds will continue into the morning. As the surface ridge axis approaches during the afternoon, may see some holes in the overcast develop, but not expecting much in the way of clearing. Will only see a small rise in temps into the middle to upper 30s. .LONG TERM...Monday Night Through Sunday Issued at 251 PM CST Sun Nov 17 2019 Mostly cloudy skies and generally dry conditions are anticipated as a ridge of high pressure moves through Monday evening. A warm front will impact the forecast area late Monday night into Tuesday morning, but moisture and deep saturation will be limited. Have raised pops to chance category, and gone with a light mix of snow and freezing drizzle. Roads may be slippery in spots for the Tuesday morning commute. A stronger low pressure system is expected to arrive Wednesday night into Thursday, and the GFS/ECMWF have come into better agreement on a track through southeast Wisconsin. Low-level thermal profiles and thicknesses would suggest rain across all but the far northwest part of GRB CWA by early Thursday, with the rain/snow line pushing southeast across all of north central WI Thursday morning. Could see 1 to 3 inches of accumulation in our northwest counties before the system pulls out midday Thursday. Farther southeast, a good slug of moisture, with PWATs exceeding 1 inch, will lead to moderate rainfall late Wednesday night into Thursday morning, with rainfall totals possibly reaching a half to three-quarters of an inch. With frost depths already at 6 inches or more, runoff from the rain could cause minor flooding issues. Have bumped up pops to likely/categorical over the entire forecast area. As the low pressure system exits, there will be potential for a brief period of light lake effect snow showers over north central WI Thursday night. Models have come into better agreement for the weekend, with dry northwest flow and a storm track remaining north of the forecast area. Looks like a generally dry weekend, with temperatures near seasonal normals. && .AVIATION...for 00Z TAF Issuance Issued at 620 PM CST Sun Nov 17 2019 A mix of LIFR/IFR/MVFR CIGS and VSBYS were found across the area during the early evening hours, with the poorest conditions across central and north central WI, as a weak front crosses the state. A wintry mix was also pushing across the area. Look for these poor flying conditions to continue through the evening hours with a mix of light snow, drizzle and freezing drizzle continuing. However, as the front exits the area later this evening, CIGS/VSBYs are expected to slowly improve from west to east overnight into Monday morning, but conditions look to remain MVFR through at least Monday morning. CIGS will climb close to or possibly into low-end VFR range Monday afternoon. Winds will remain on the light side through the TAF period. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......Kieckbusch AVIATION.......Bersch
Area Forecast Discussion
National Weather Service Louisville KY
1006 PM EST Sun Nov 17 2019 .Forecast Update... Issued at 1006 PM EST Sun Nov 17 2019 A sharp upper trough is entering the Mississippi Valley this evening. Vorticity will increase in the base of the trough with a maximum dropping into the Tennessee Valley during the pre-dawn hours. Upstream radars are showing targets aloft in mid-level clouds along and ahead of the trough axis, but the hydrometeors are largely evaporating as they fall into very dry sub-cloud air with dew point depressions on the order of 20 to 30 degrees F. Since 22Z little more than a trace to 0.01" of rain has been reported at southern Illinois observation sites. Will continue chances of sprinkles tonight in southern Indiana and central Kentucky with a small chance of isolated measurable rain as the trough moves into the region. As temperatures fall into the lower and middle 30s by dawn a few flurries could mix in with the sprinkles. && .Short Term...(Tonight through Monday evening) Updated at 320 PM EST Sun Nov 17 2019 An upper trough, now near the KS/MO border, will swing into our region Monday morning. Moisture is limited ahead of this feature, but a few models still are trying to squeeze out some light precip for the morning hours and even into the afternoon hours east of I- 65, perhaps as a drizzle. Current forecast calls for slight chances of measurable precip. We may have a brief window between the upper clouds moving through and the lower clouds developing, as shown by GFS and RAP time-height sections, to allow for a brief cool down under calm/light winds. That window is 2-3 hours, according to those models, but given upstream coverage on satellite, will lean towards more cloud cover tonight. Even if we do end up with some wintry precip/flurries road temperatures should be warm enough to quickly melt it, given that rates would be very light. Expect cloud cover to linger through much of the day Monday, making for a dreary day. Despite that dreariness, statistical guidance is calling for temperatures to reach the upper 40s and even a few 50s across southern KY. Winds should turn to westerly for most areas by afternoon, so not sure where the guidance is picking up on the warmer values. That said, given that the spread is pretty narrow on model solutions, will only cut down on the blended forecast by a degree. && .Long Term...(After midnight Monday night through Sunday) Updated at 250 PM EST Sun Nov 17 2019 Another quick-moving wave looks to bring another low-end chance for precip Tuesday. Precipitable waters are just a little higher with this system but temperatures Tuesday morning may be a degree or two closer to a point where we get some mixed precip early, mainly along and north of I-64. It should be noted that the Euro and CMC solutions show the QPF, whereas the GFS and NAM solutions are much more spotty in coverage. Blended model guidance with some of the better-performing 36-48 hour models of late and went with slight chances for measurable precip. Soundings show that moisture is fairly shallow, so we may end up with more of a measurable drizzle than rain/snow. Also, not expecting any travel impacts here, as in the Monday morning case, with road temps still well warm enough. Midweek offers us a brief break from these precip chances, as well as a warmup as ridging builds in aloft. That will be short-lived however as a stronger low pressure system moves across the Midwest Thursday. These rain chances could linger into Friday as the associated cold front briefly stalls somewhere in the vicinity of the Ohio Valley and then gets another upper trough to kick it out either Friday or Saturday. Model guidance diverges quite a bit with the timing here, so will have to spread out timing for precip in these periods. Type is in question given that spread, but as with previous forecast, qpf ended up more in the liquid variety with this set of blended guidance. && .Aviation...(00Z TAF Issuance) Issued at 650 PM EST Sun Nov 17 2019 Current satellite imagery shows high clouds streaming across the region, with VFR conditions expected to prevail for the beginning of the TAF period. Ceilings will begin lowering into MVFR range at KHNB around 10Z and push eastward towards the other TAF sites throughout the day as an upper level trough swings across the OH Valley. Some light precip will be possible tomorrow, but confidence is too low to include any mention in the TAFs. Ceilings will begin to lift above fuel-alternate and into VFR towards the end of the TAF period. Expect a more westerly wind tomorrow, generally under 10kts. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...13 Short Term...RJS Long Term...RJS Aviation...JML
Area Forecast Discussion
National Weather Service Marquette MI
524 PM EST Sun Nov 17 2019 .SHORT TERM...(This evening through Monday) Issued at 427 PM EST SUN NOV 17 2019 Latest WV imagery and RAP analysis indicated an upstream mid/upper level trough from northwest Ontario into the Upper Mississippi Valley. At the surface, southerly winds prevailed ahead of the associated sfc trough through western Lake Superior into northwest Wisconson. The combination of weak isentropic lift and 700-300 qvector conv ahead of the mid level trough supported light snow/rain over mainly the east half of Upper Michigan. With the pcpn diminshing over the west, upstream obs indicated the potetnial of some light drizzle or freezing drizzle as moisture above -10C dwindles. Tonight, with abundant low level moisture over the region and weak qvector conv and low level conv near the trough, patchy dz/fzdz is expected to continue this evening over the west. The best chance for some icing will be in the higher terrain west where upslope westerly flow develops this evening. Over the east, the pcpn will also gradually diminish but may linger a bit longer where some lake enhancement is possible with southerly flow off of Lake Michigan. Temps should remain high enough for pcpn to remain as light rain or drizzle. Monday, some lingering light pcpn may linger over the east as the mid level trough will be slow to exit the region. With only a shallow moist layer, mainly just dz/fzdz is expected. Otherwise, look for seasonable November temps with highs in the mid to upper 30s under cloudy skies. .LONG TERM...(Monday night through Sunday) Issued at 338 PM EST SUN NOV 17 2019 Some light, scattered precipitation is possible Tuesday as a weakening shortwave traverses the region. Wednesday looks mostly dry but all eyes are on the potential for the first widespread system snow this winter as a low will eject out of the panhandles region and head northeast Wednesday evening. The sfc circulation will be strengthening Thursday as a mid-level, positively tilted trough digs out of the northern Plains. Models continue to come into better agreement on a track that favors significant synoptically driven precipitation across the Upper Peninsula, but there remain questions about the strength of the low and extent of the cold air and thus precipitation types. Better agreement exists in a brief period of NW wind lake effect snow following this system through much of Friday, shutting down Friday night. Then, another shortwave pushing southeast through Ontario may clip the region with more light snow chances late Saturday into Sunday, especially east. Monday night into Tuesday, as a weakening shortwave trough axis approaches from the WNW, some light mixed precipitation is likely for portions of the area. Best chances are over the far west with additional slight chances over the far east. A quick dusting of snow will very likely be followed by a brief period of drizzle/freezing drizzle as mid-levels dry out a little and scour out ice nuclei. Could be a couple hundredths of sfc ice accumulation, just enough to potentially cause some slick spots on roads and sidewalks for the Tuesday morning commute. Best chances for this will be in Gogebic and Ontonagon Counties. Wednesday brief ridging will poke into the region from the SE, but this will be short lived. NAM shows a much faster progression of an initial round of isentropic lift and associated precip that could affect the west half in the afternoon but chances are good that this will hold off until the evening or overnight. The main event for this week will be the deepening low pushing through IA into WI Wednesday night, with a precipitation shield filling in through the early AM hours of Thursday over the UP and then exiting in the afternoon. Model agreement in the track is much better than yesterday, but significant differences remain in the sensible weather. While the GFS/ECMWF would suggest low level temperatures supportive of mainly rain except across the far west, the GEFS ensembles are trending colder and generally produce more snow. In fact, at MQT the deterministic soln is at the very bottom of the 12Z GEFS snow envelope. The main exception is that east of US- 41 in all likelihood more rain will mix with the snow regardless. If snow were to be the more dominant precip type across central/western portions of the region, it would be of the heavy and wet variety. On the high end, 6-9" snowfall accumulations wouldn`t be out of the question in some spots, but there remain several model solutions that keep the majority of the precip in liquid form and thus only produce a couple of inches of snow mainly west on the backside of the system as cooler air moves in. Hopefully things will become clearer as we add higher resolution models to the mix over the next 24-48 hours. Some NW wind LES is likely Thursday night and Friday as winds strengthen and 850 temps drop to somewhere in the -11C (ECMWF) to - 14C (CMC) range. But this will be cut off quickly on Friday afternoon over the west and evening east as mid-level shortwave ridging pushes the trough axis eastward and winds shift back to the SW. Could be some additional light snow returning as early as Saturday afternoon, mainly east, but marginally better chances will come overnight and Sunday. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 524 PM EST SUN NOV 17 2019 With abundant low level moisture over the region as a trough moves through, expect mainly IFR or low end MVFR conditions to prevail through tonight. Some freezing drizzle may also be possible at CMX where upslope westerly flow develops. Enough dry air moves in Monday for conditions to lift to MVFR, first at IWD. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 414 PM EST SUN NOV 17 2019 Lingering gusty winds of 20-30 knots over the far eastern lake will continue to diminish this evening. Winds will veer more west to northwesterly and decrease further into Monday, relaxing below 15 knots. Winds will remain relatively calm through Wednesday night as a trough hangs over the area followed by a brief ridge. Models then indicate a low pressure system will develop across the Central Plains and lift northeast toward Lake Huron Thursday evening and then into Quebec on Friday. This will bring the next chance at northwest winds approaching 30 knots, and possibly exceeding 30 knots over the eastern lake by Thursday evening. Winds will then gradually subside below 20 knots early Friday morning. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...KCW AVIATION...07 MARINE...KCW