Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/14/20

Area Forecast Discussion
National Weather Service La Crosse WI
646 PM CST Mon Jan 13 2020 .UPDATE... Issued at 639 PM CST Mon Jan 13 2020 The winter weather advisory has been expanded to cover the remainder of the forecast area. The RAP has been consistent through the late afternoon and early evening of showing the potential for freezing drizzle to occur behind the snow band. Forecast soundings show a loss of ice in the clouds occurring quickly behind the snow while the lower portion of the sounding remains saturated with plenty of lift occurring through this saturated layer. Already seeing some reports of freezing drizzle upstream across southeast South Dakota and northwest Iowa. To further complicate things, fog is also occurring with the freezing drizzle with visibilities under two miles at times. With temperatures remaining below freezing tonight, this could also add a some light riming to the mix. With the combination of snow, freezing drizzle and fog expected to create slippery to hazardous driving conditions, felt a winter weather advisory was the best route to go. If the RAP is correct, parts of the area could still have a potential for freezing drizzle to occur into early Tuesday morning and the advisory may have to be extended in time if this is the case. && .SHORT TERM...(Tonight through Tuesday) Issued at 153 PM CST Mon Jan 13 2020 Eyes are on fairly potent mid-level wave moving into the central Plain from the Rockies this afternoon per latest GOES water vapor. This wave will spin up surface cyclogenesis over western MN this evening with a strong push of 925-700mb isentropic lift into our area. Rap shows strong omega in the saturated -12 to -18C range dendritic growth zone. Looks like this strongest lift will be during the evening hours, then pushing east of the area after midnight. Also of note will be the potential/likelihood for loss of ice in cloud as the snow tapers off. So, could see a hour or two period of some light freezing drizzle. Right now, looks like the highest snow totals tonight (2-3+ inches) will be from portions of northeast IA/ southeast MN into west-central and northwest WI. Lesser amounts of a dusting to 2 inches can be expected across the rest of the forecast area. Models indicating nice push of drier air into the area Tuesday behind the departing wave of low pressure and incoming ridge of high pressure from the Plains. This should act to scour out stratus from west to east by afternoon. .LONG TERM...(Tuesday night through Monday) Issued at 153 PM CST Mon Jan 13 2020 Winter weather fans, rejoice! After the recent mild weather, this is your week to enjoy some more typical January conditions, with several additional risks for snowfall expected through the weekend. The overall pattern the next 7 days looks to retain a bit of a Pacific-influenced/zonal look, with periodic shortwaves traversing the region and linking up with sufficient colder air to deliver occasional wintry precipitation chances. After tonight`s bout of snow, the next risk looks to come later Tuesday night into Wednesday morning as the next shortwave quickly works through the region. Pretty solid axis of deep layer QG-upward forcing and low level warm advection ascent should have little trouble saturating an initially dry atmosphere, and much like recent events, can`t rule out a little freezing drizzle at the tail end Wednesday as deeper moisture scours out. However, this system is a fast mover, with decent forcing but limited residence time for any one location, suggesting more of a 1-2 inch event for most, perhaps a little higher toward central Wisconsin with some hint of a better frontogenetic axis bisecting the Highway 29 corridor. Synoptic forcing quickly dwindles later Wednesday, though may still contend with some flurries as sharp low level cold advection pushes whatever residual stratus remains well into the dendritic growth zone. Otherwise, the Wednesday night-Thursday period looks quiet but rather chilly as cold Canadian high pressure slides through the region, with highs on Thursday likely only in the single digits and low teens and overnight lows near or below zero pending cloud trends. Looking even farther out, the Friday-Saturday period remains of high interest with increasing consensus for a stronger upper trough to work through the region. Still some spread among ensemble members with regard to the track of the surface-700mb lows (most are south of the local area), but deeper moisture from an open Gulf of Mexico and slower advertised movement of that feature suggests at least a risk for higher snowfall totals. Again, plenty of details to be worked out, but this one bears close watching, with little weather of note expected from Sunday into Monday as another round of colder high pressure builds south into the area. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 504 PM CST Mon Jan 13 2020 A challenging forecast from a precipitation type standpoint. A short wave trough will move across the region overnight providing plenty of forcing for precipitation production. Expect precipitation from this system to spread over both airports this evening with conditions going down to IFR in snow. Forecast soundings from the RAP late this afternoon suggest there is a relatively short 2 to 3 hour window for the snow before ice aloft is lost in the clouds which should make the dominant precipitation type freezing drizzle. Observations downstream across eastern South Dakota and Nebraska already confirm the presence of the freezing drizzle along with fog. Based on this and the forecast soundings, will maintain the IFR conditions into early Tuesday morning for both freezing drizzle and fog. As the winds swing around to the west, dry air will start to work in that will first shut off the precipitation production and fog and then allow the clouds to scatter out in the late morning/early afternoon. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Winter Weather Advisory until 6 AM CST Tuesday for WIZ017-029- 032>034-041>044-053>055-061. MN...Winter Weather Advisory until 6 AM CST Tuesday for MNZ079- 086>088-094>096. IA...Winter Weather Advisory until 6 AM CST Tuesday for IAZ008>011- 018-019-029-030. && $$ UPDATE...04 SHORT TERM...DAS LONG TERM...Lawrence AVIATION...04
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
607 PM EST Mon Jan 13 2020 .AVIATION... Low level moisture will be trapped through the TAF period, with the only debate being whether we are looking at IFR vs MVFR cigs. Cooling boundary layer this evening leading to MVFR cigs, followed by modest surface/near surface moisture increase tonight should lead to cigs falling at and below 1000 Feet, with the higher confidence across the northern TAF sites. Cigs look to struggle to rise much during tomorrow until the wind shifts to the southwest, but even then likely only rising into LOW MVFR. Light and variable winds this evening with surface high pressure in place. The high will drift east, allowing winds to become southeast late tonight into tomorrow morning, but still probably under 10 knots. A wind shift to southwest and an increase in winds will then occur in the mid afternoon with a surface trough passage. The low level convergence with this trough could be enough to touch off some light drizzle. DTW THRESHOLD PROBABILITIES... * High for ceilings at or below 5000 ft through the taf period. * Low for light drizzle 10-17Z Tuesday. && .PREV DISCUSSION... Issued at 328 PM EST Mon Jan 13 2020 DISCUSSION... High frequency shortwave pattern will continue to impact Southeast Michigan through midweek as quasi-zonal flow remains in place. No shortage of shortwaves ejecting out of and under the parent closed upper level PV anomaly over British Columbia. Shortwave ridging in tow of early day absolute vorticity maximum/shortwave will support lowering subsidence during the remainder of the afternoon. Earlier this morning, mixing depths were just high enough at 6.0 kft agl to allow for some perplexing ice nucleation and some rogue light snow shower activity near and along I 96. Since then there has been less evidence of observed precipitation with skies here at the office become increasingly brighter. This lends increased confidence in the lowering inversion which should at least help in thinning out the stratus overcast. Colleagues point out that boundary layer thermal vortices, swirling out over the Great Lake basins, are causing some disruption to the stratus field with clearing at midlake. This points to very thin cloud field/potential for ascent and will remove any mention of flurries for the remainder of the afternoon and evening. The next shortwave is scheduled to lift northward and pivot into negative tilt across the Central Great Lakes by 12Z Tuesday. Certainly a respectable structure to the shortwave and what at first glance appears to be some decent warm advection. System relative isentropic analysis shows a very brief duration of system relative isentropic ascent between 12-15Z. The biggest negative factor for the event is the real struggle for any meaningful deep saturation. Models show a tangible ribbon of 850-725mb equivalent potential temperature dragging across Southeast Michigan. However, forecast soundings tell the story that saturation is virtually non-existent in the 3.0-6.0 kft agl layer. The nam is the most bullish, while the RAP struggles and the ECMWF has been very consistent with no QPF. The bottom line is the best case ceiling for this event is for a trace or hundredth of liquid. Did maintain a chance of drizzle for forecast continuity, with surface temperatures at/above freezing. Late Tuesday and Wednesday the upper level flow over North America is expected to become split flow with the northern stream over Wisconsin and Michigan. Models continue to advertise some phasing of the two streams over the central part of the country with coupled jet dynamics resulting in a wave of low pressure through Michigan. Models show a coherent, deep low pressure center tracking through central Wisconsin Wednesday afternoon with a wing of warm advection lifting into the state. There are difference with how the models handle the system. The ECMWF is much more phased and developed, while the NAM maintains separation between the northern and southern stream trajectories/moisture. Regardless, what is of higher confidence is the lack of true cold air advection in advance of the low which supports a rain/mix across the cwa and temperatures will be balmy possibly ranging middle 30s north of middle 40s south. Will continue to go with a chance/likely of rain and snow across the cwa. The fail point to the forecast and something to monitor is what the trends become of how phased the system is. A more developed cyclone will result in greater cold side deformation and minor snow accumulations clipping the northern cwa, primarily Wednesday evening. High amplitude ridging and arctic high pressure is forecasted to build into the region Thursday and Friday. Temperatures will cool down with the +1045mb arctic high but the lack of snow cover will temper conditions. MARINE... A weak low pressure system will pass over the northern Great Lakes Tuesday which will cause southeast winds to ramp up a bit during the day. Air will be relatively warm which will limit gust potential to around 25 knots with the best chance of the highest gusts coming in the evening immediately behind a cold front. There is a brief opportunity for waves to reach 4 feet along the nearshore waters near the tip of the Thumb with the sustained along shore flow for several hours but appears too brief to issue a Small Craft Advisory at this time. Another stronger low will then track across the southern Great Lakes Wednesday into Wednesday night. Increased northwest flow will usher in a colder airmass which will lead to unstable conditions over the waters for Thursday. Gust may reach 30 knots building wave heights and increased mixing depths may result in snow squalls as well. Large area of high pressure then arrives Thursday night into Friday, assuring lighter winds (under 20 knots) but still cold and potentially light snow showers lingering into Friday morning. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....SF DISCUSSION...CB MARINE.......DRK You can obtain your latest National Weather Service forecasts online at
National Weather Service Hastings NE
950 PM CST Mon Jan 13 2020 ...Short Term Update... .UPDATE... Issued at 949 PM CST Mon Jan 13 2020 ..Dense Fog Advisory Counties Adjusted a Bit.. Ah, the joys of forecasting/nowcasting fog and dense fog when it`s not a "completely straightforward" situation. Based on automated airport obs from Smith Center KS (K82) along with calls to county dispatch/law enforcement, was compelled to add Webster/Smith/Osborne to the Dense Fog Advisory, as dense fog issues crept a bit farther west into those counties than earlier anticipated, and seems to be very-much-tied to the fringes of the stubborn lingering stratus deck in that area. Meanwhile, opted to "ditch" Nance/Merrick from the Advisory (and probably could have let go of a few other northeast counties as well), as frankly there has been little sign of dense fog formation thus far in that area, which will also be transitioning to more of a westerly breeze in the next few hours, making more than brief/fleeting dense fog fairly unlikely. As Dense Fog Advisories go, this one is struggling to amount to much for MOST of the issuance area, but again, there have been enough reports of dense fog in some of our southern counties to at least justify the existence of the headline in the first place. As outlined earlier, any fog/dense fog should scour out of our CWA from west-to-east well before sunrise. UPDATE Issued at 657 PM CST Mon Jan 13 2020 ..Dense Fog Advisory Issued For Eastern CWA through 3 AM.. In collaboration with OAX/TOP/ICT, we have issued a Dense Fog Advisory valid until 3 AM for all 11 of our counties east of the Highway 281 corridor. To be fair, this is not a multiple-hour "can`t see your hand in front of your face" situation for most of the Advisory area, but based on visibility progs from the HRRR/RAP, the majority of the Advisory area appears favorable to see at least a few hours of visibility near-to-below 1/4 mile at some point tonight (already evident at Hebron airport). Fortunately, drier low-level air gradually advecting in behind the passing surface trough will scour out fog/low clouds from west-northwest to east-southeast as the night wears on. In fact, overnight shift may be able to cancel a few of the northern counties (such as Nance/Merrick/Hamilton) a few hours early, while our far southeast (Thayer/Mitchell) could hold onto dense fog right up until the currently-slated 3 AM expiration. On one last note, we probably cannot rule out some patchy/brief dense fog just west of the official Advisory area (Hwy 281 corridor counties) as this is where the back edge of the low cloud deck currently resides. As a result, have issued an SPS to cover the more fleeting nature of any possible dense fog in these counties. && .SHORT TERM...(This evening through Tuesday) Issued at 239 PM CST Mon Jan 13 2020 Aloft: WV imagery and RAP tropopause analyses indicated low- amplitude SW flow was over the Cntrl Plns within basically zonal flow. A wk shrtwv trof was over WY/CO/NM. This trof will lift NE and cross NEB/KS this evening. Heights will rise a bit in its wake...leaving W-WSW winds thru tomorrow. Another wk shrtwv trof will move onshore in the W tomorrow. Surface: 1029 mb high pres was over the OH Vly while the main polar front was stationary from the GtLks acrs SD into MT. Wk 1008 mb low pres was over WY. This low will move E along the front tonight. It will drag a sfc trof thru the CWA followed briefly by 1020 mb high pres. Low pres will begin forming over CO tomorrow. Rest of this afternoon: Skies are partly-mostly sunny over Furnas/Gosper counties. This should spread N and E as the shrtwv trof departs. So expect gradually dcrsg clds...espcly W of Hwy 281. E of Hwy 281 is another issue. As always...low stratus and fog during the day are a big fcst problem and that is the lowest confidence portion of this fcst. Mdls don`t handle it well and so we really are winging it as it when improvement might occur. Tonight: Believe we will eventually see improvement/clearing of the low stratus over most of the CWA. Some low-lvl WAA will occur with the passage of the sfc trof late this afternoon/evening. This should shove whatever low stratus is left E of the CWA. However...this stratus has suppressed daytime temps...leaving them perilously close to the dwpt and near saturation. So with clearing and light winds...fog expect should easily redevelop E of Hwy 281...and espcly along Hwy 81. It may not last all the way thru the night. Even the fog-heavy NAM indicates improvement late tonight as drier air/dwpts drift in. Tue: Sunny and mild. Just about everywhere should reach the 40s. Probably the warmest day of the next 7. A very nice day with light winds. .LONG TERM...(Tuesday night through Monday) Issued at 239 PM CST Mon Jan 13 2020 Aloft: The last 2 runs of the GFS-FV3/EC/CMC/UKMET are tightly- clustered on some moderate amplification of the longwaves...but with the flow remaining progressive. Admittedly...this is not how we envisioned last week at this time. It looked as though the PNA pattern would turn negative and remain negative for the foreseeable future. Zonal flow will cont into Wed. The wk Wrn USA shrtwv trof mentioned above will cross NEB/SD late Tue night into Wed AM. Upstream amplification over the N Pac will result in formation of a new trof off the W coast. This will force a ridge to build over the Wrn USA Wed night. This ridge will cross NEB/KS Thu followed by SW flow until the E Pac trof crosses the rgn which will be Fri. The progression of the flow is then fcst to slow or halt altogether as the Aleutian low dvlps...with a downstream ridge building over the Wrn USA/Can. So once the Fri trof moves by... increasingly amplified NW flow is fcst over NEB/KS. Surface: The wk CO low that forms Tue will head ENE acrs KS Tue night. This low will yank the stationary front (currently over SD) S thru the CWA Wed morning...with strong high pres nosing S from Wrn Can. This 1045 mb high is fcst to slide into the Nrn Plns Thu and into ON/QB Fri. Meanwhile...low pres will form over CO and emerge into KS Fri...with a warm front lifting N to near I-70. This low will deepen on its way into the GtLks Sat with Canadian high pres nosing in here. It appears that the Arctic front will move into NEB/KS and become stationary from NW-SE...parallel to the flow aloft Sun-Mon. Temps: will average near normal. Thu will probably be the coldest day of the next 7. Once we get into NW flow...that typically keeps the CWA on the SW fringe of the Arctic air...with wild swings in temps. Brief intrusions of Arctic air will alternate with downslope-warmed air about every 2-3 days. Precip: The only event currently envisioned is Thu night into Fri. The last 2 runs of the GFS-FV3/EC/CMC are in remarkable agreement for this far out. Most of the precip should fall over the E 1/2 of the CWA with 0.10-0.25". Probably less than 0.10 W of Hwy 281. It`s a little early to get into specifics about ptype...but both the 12Z EC/GFS indicate potential for a slight warm nose. So we could be looking at a light wintry mix of SN/IP...possibly mixed with -FZRA. The depth of the sfc-based cold air will be the key. Based on how it looks now...this looks like a solid advisory- level event...espcly with the Fri AM commute potentially impacted. Stay tuned for more details as this is still 78 hrs away. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday) Issued at 657 PM CST Mon Jan 13 2020 General overview: The majority of the period is actually a fairly high-confidence VFR forecast (especially for KEAR). However, KGRI currently resides near the far western edge of a pesky low stratus deck (IFR/MVFR), which will likely linger for at least a few more hours before departing eastward. Both sites (but again especially KGRI) could see at least a few hours of fairly light fog this evening, with MVFR visibility ongoing at KGRI. Although VFR ceiling/visibility is expected to return to KGRI within the next 3-5 hours, attention then turns to a brief period of low level wind shear (LLWS), which has been introduced to both sites from 05-08Z. Read on for more wind-related details... Winds (including LLWS): Starting with surface winds, light breezes tonight (under 10KT) will gradually turn from southerly to westerly behind a passing surface trough, then become light/variable direction Tuesday morning before becoming steadier from the southeast in the afternoon (around 10KT). As for the LLWS 05-08Z, this was introduced to account for a passing corridor of west-northwesterly 30-35KT winds within (roughly) the lowest 1,000 ft. above the surface. The net result will be somewhat marginal (albeit mentionable) shear magnitude of around 30KT between the surface and this level. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Dense Fog Advisory until 3 AM CST Tuesday for NEZ049-063-064-076- 077-085>087. KS...Dense Fog Advisory until 3 AM CST Tuesday for KSZ006-007-018-019. && $$ UPDATE...Pfannkuch SHORT TERM...Kelley LONG TERM...Kelley AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Houston/Galveston TX
946 PM CST Mon Jan 13 2020 .NEAR TERM [Rest of Tonight]... Went ahead and pulled the trigger for a Dense Fog Advisory for all of SE TX tonight (previously, just along the coast). Conditions do remain favorable for the continued development of fog overnight in to tomorrow morning. Of note...some of the latest short models are indicating that the lower visibilities could persist well into the afternoon. But for now, will keep the expiration time for this fog advisory for inland locations at 10 AM...with sea fog likely ling- ering over the bays/nearshore waters all day. 41 && .PREV DISCUSSION... /Issued 400 PM CST Mon Jan 13 2020/... SHORT TERM (Tonight and Tuesday)... A warm front lies just off the Upper Texas Coast and this feature is serving as a focus for showers and isolated thunderstorms. Much warmer air is poised to enter SE TX and temperatures tonight will remain nearly steady or perhaps slowly rise as the warm front moves north. Warm and moist air will flow over the cooler shelf waters and periods of sea fog will develop and will likely affect coastal communities and a Dense Fog advisory may be required later tonight. In addition to the fog, warm air advection will also produce periods of light rain or drizzle. All in all, tonight will be a murky damp mess. Late tonight or early Tuesday, the GFS, HiRes ARW and the 18z HRRR all show convergence increasing along the US 59 corridor. Omega also increases significantly and precip will likely expand in coverage and increase in intensity prior to sunrise. Will be carrying likely PoPs for much of the area and will include thunder as fcst soundings show PW values near 1.80 inches and K index values in the upper 30`s. Mid level lapse rates look less than today but sufficient to generate thunder. It should be warmer than today but have some concerns that precip and extensive cloud cover will keep temps a little cooler than the blends would suggest. 43 LONG TERM (Tuesday night through Monday)... Upper ridging laid across the Gulf will ultimately control our weather pattern through a cold frontal passage on Saturday, There will be a series of weak disturbances (enhanced PVA) that will stream across Central Texas within the mean westerly steering flow and provide just enough lift to maintain subsequent day (mainly far interior) low to moderate POPS for showers and isolated thunderstorms. The main story for this upcoming work week is still the unseasonably warm and humid conditions as the eastern Texas remains entrenched under a stout onshore flow regime. Nocturnal fog will remain an issue throughout the week especially over the nearshore Gulf and local Bay waters and surrounding communities. Low overcast with periods of sea and inland fog lowering visibilites from around 5-6 SM to under a mile will likely occur but just too difficult to pin point timing of onset. So, best to monitor and react as the soup thickens up with short fuse fog advisories. Precipitation will be very light, mist to light showers through the remainder of the work week. A cold front is forecast to cross southeast Texas sometime on Saturday during the day. POPs will increase to high moderate over the central and southern forecast area ahead of the front through Saturday. As of now, higher precipitation probabilities for low QPF. North winds kick in later Saturday and will veer easterly through early next work week. The passage of a shallow 5H trough on Monday will again pick rain chances back up but, again, it will be 20-30% chance for periodic showers/isolated storms this time next week. 31 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 58 72 65 77 64 / 50 50 20 30 20 Houston (IAH) 60 76 67 78 66 / 50 60 10 20 20 Galveston (GLS) 62 70 66 72 65 / 30 40 10 10 20 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Dense Fog Advisory until 10 AM CST Tuesday for the following zones: Chambers...Coastal Brazoria...Coastal Galveston... Coastal Harris...Coastal Jackson...Coastal Matagorda... Galveston Island and Bolivar Peninsula...Inland Brazoria... Inland Galveston...Inland Jackson...Inland Matagorda. GM...Dense Fog Advisory until noon CST Tuesday for the following zones: Coastal waters from Freeport to Matagorda Ship Channel TX out 20 NM...Coastal waters from High Island to Freeport TX out 20 NM...Galveston Bay...Matagorda Bay. && $$
Area Forecast Discussion
National Weather Service Lincoln IL
839 PM CST Mon Jan 13 2020 .SYNOPSIS... Issued at 245 PM CST Mon Jan 13 2020 Cloudy skies with temperatures in the mid 30s to lower 40s were the general conditions on Monday. Conditions will remain cloudy overnight, with Tuesday morning lows in the upper 20s to mid 30s. && .UPDATE... Issued at 834 PM CST Mon Jan 13 2020 Mid evening satellite imagery shows rapid erosion of the stratus from the southeast spreading northwest across central Illinois. Low clouds have cleared east of I-57 and the clearing is expected to continue to work towards the I-55 corridor over the next two to three hours. It remains uncertain how much longer this will continue, but RAP and HRRR low level RH fields seems to have a decent handle on near term trends. They do show stratus redeveloping from the south/southwest after midnight, though likely not as widespread as what was occurring earlier. Overnight temperature trends and possible fog development are the main areas of concern with impacts from cloud cover or lack thereof overnight. Relied heavily on RAP/HRRR hourly temp trends dropping temps a few degrees in the east with non-diurnal trends after midnight as cloud cover redevelops. && .SHORT TERM...(This evening through Tuesday) ISSUED AT 245 PM CST Mon Jan 13 2020 Strong low level inversion seen in morning sounding will continue to keep moisture trapped and so overcast conditions to continue overnight into Tuesday. Moisture channel imagery shows weak upper wave moving over NE-KS will continue to track over northern portion of IL. This will bring slight chance of light rain to the extreme northern parts of CWA tonight. Pcpn will be minor though. A weak high pressure area will drift across Il on Tuesday, as the next system forms in the west. .LONG TERM...(Tuesday night through Monday) ISSUED AT 245 PM CST Mon Jan 13 2020 For Tuesday night, the second short wave in the fast upper flow over the midwest, will move toward IL, with some light pcpn again developing in the overrunning pattern toward Wednesday morning. With temps around freezing, some light freezing pcpn will be possible in the northwest parts of the CWA Wednesday morning, before changing to all rain. Rainfall amounts will be light Wednesday, as the moisture is limited and this wave again moves through quickly. High pressure will be in control through Thursday. By late Thursday night, a major shortwave with a deepening surface low will be exiting the Rockies, with overrunning pcpn moving into IL, starting on Friday and continuing into Saturday. This system is a major one, but the models differ on the track, amount of cold air, and moisture. For that reason, will message that a system is expected, with the pcpn will start out as snow Friday, and change over to rain in the south and central sections. Is too early to mention amounts of snow, but will highlight uncertainties, and that the system will be significant. The northern third of CWA will have the best chances for the highest accumulations. Heavy rain will also be a problem, especially over areas where flooding was a result of the previous weekends rainfall. Will have to watch amounts over region, as they may make more flooding possible. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 527 PM CST Mon Jan 13 2020 A weak warm front will lift across central Illinois again late this evening and overnight. Southeast winds ahead of the front will veer to the southwest with passage of the front. Anticipate lowering ceilings as the front approaches to IFR or LIFR along with some possible fog, though have low confidence in how thick or widespread fog will become. Should see modest improvement with ceilings and a lower fog threat behind the front, though don`t expect VFR conditions returning through the period. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Deubelbeiss SYNOPSIS...Goetsch SHORT TERM...Goetsch LONG TERM...Goetsch AVIATION...Deubelbeiss
Area Forecast Discussion
National Weather Service Paducah KY
956 PM CST Mon Jan 13 2020 .UPDATE... Issued at 956 PM CST Mon Jan 13 2020 Have updated the forecast to catch up to satellite and METAR trends. Skies have cleared over the northwest portions of the region and temperatures have already fallen farther than expected. Winds are also light and variable. All this has resulted in near saturation and some light/MVFR fog development. Threw in some patchy to areas of fog over the northwest half of the area, but did not mention dense fog at this time. Just don`t have enough confidence in the sky forecast at this time. Blended in the cooler HRRR temperatures and dewpoints with the existing grids through the overnight hours. Ended up with a stronger gradient from southeast to northwest across the area. As for the precipitation chances, it should be limited to the far southeast corner of the area, where an elevated thunderstorm cannot be ruled out. No change to the thunder forecast, but did shave off the northwest edge of the PoP area. UPDATE Issued at 543 PM CST Mon Jan 13 2020 The AVIATION section has been updated for the 00Z TAF issuance. && .SHORT TERM...(Tonight through Wednesday night) Issued at 100 PM CST Mon Jan 13 2020 Some breaks in the low clouds have finally formed over west KY. The models suggest they may redevelop tonight. Will carry considerable cloudiness, as high pressure moves east. We will carry a chance of rain over the SE 1/3 of the area, primarily west KY overnight, with even a slight chance of thunder just north of the TN state line. This area should move off to the east early Tuesday morning. Next rain chances moves in late Tuesday night and continues Wednesday as low pressure tracks from Missouri to the Ohio Valley region. Coverage should be scattered, with a slight chance of thunder southern portions of the area. Dry Weather returns Wednesday night as high pressure builds in. Temperatures will be above normal. .LONG TERM...(Thursday through Monday) Issued at 100 PM CST Mon Jan 13 2020 Dry weather will prevail Thursday and Thursday evening. After midnight, there is a chance of precipitation into Missouri, possibly to the MS River. Tricky temperature forecast and thermal profile. So we`ll have to monitor for a possible light wintry mix at the onset of this next round of precip. However, if you believe the EC/CMC solutions, there will be nothing to be concerned with, no precip advertised til Friday. Otherwise rain chances increase Friday, peak Friday night, end early Saturday. Decent rainfall amounts possible, over 1 inch not out of the question. Dry weather returns for later Saturday through Monday as high pressure builds back in. Above normal temperatures through Saturday will return to near normal Sunday through Monday. && .AVIATION... Issued at 543 PM CST Mon Jan 13 2020 MVFR ceilings have all but left the area, but much of the available guidance is not aware of it. Definitely went on the optimistic side of guidance and kept the area mostly VFR through the period. A band of MVFR ceilings may work into southeast Missouri and southern Illinois in the morning before scattering out. Some light rain may work into west Kentucky late tonight, but it is not likely to reach KPAH or KOWB. There should be an increase in lower VFR clouds over much of the area overnight, but MVFR or lower ceilings should stay southeast of the TAF sites. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...DRS AVIATION...DRS
Area Forecast Discussion
National Weather Service Riverton WY
403 PM MST Mon Jan 13 2020 .SHORT TERM...(This evening through Tuesday night) Will continue with the Winter Weather Advisory through 00Z Wednesday for western portions of the forecast area. The short term models including the HRRR model are similar in depicting a quick increase in snow tonight across the western portions of the forecast area to the west of the Continental Divide. Some mountain locations will likely have amounts closing in on a foot through Tuesday afternoon, but will stay with a Winter Weather Advisory due to expected amounts. The short wave at 500 millibars is progged by the short term models to shift eastward into the central portion of the area by after 18Z Tuesday. There will also be some scattered light snow expected across southwest through southern sections of Wyoming between 18Z Tuesday through 00Z Wednesday. Elsewhere, it will remain dry on Tuesday, with brisk to windy conditions expected from KRKS, extending northeast to KCPR. A trailing surface cold front should move through the forecast area by 00Z Wednesday. It will still be colder Tuesday night across a good portion of the area in the wake of the cold front with temps expected to be about 3-5 degrees colder for overnight lows by 12Z Wednesday. .LONG TERM...(Wednesday through Monday) Issued at 320 PM MST Mon Jan 13 2020 Wednesday the west finally gets a break and the state will be mostly dry. Unfortunately, isolated to scattered PoPs will quickly return Thursday, increasing on Friday. A trough will move into the area, bringing with it more snow across the west and south. Areas to the north and east may also see some snow from this system on Friday. Isolated light snow will linger in the northwest on Saturday and Sunday, but otherwise most of the area should remain dry. Winds will be gusty in the mountains each afternoon this week and breezy to windy across southern WY. Temperatures will slowly warm through the end of the week and then drop a few degrees again just in time for the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 352 PM MST Mon Jan 13 2020 West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals Light snow will continue to drift across the area for the rest of this afternoon, but mainly MVFR and low VFR conditions will prevail. Snowfall will begin to increase again shortly after dark as a new system moves in. After 00Z, cigs will lower and vsby will drop at KJAC/KPNA/KBPI for the rest of the night tonight. Mountains will be frequently obscured. The heaviest snow, lowest cigs, and vsby will occur after midnight tonight. Conditions will improve somewhat at these locations by Tuesday afternoon. KRKS and KJAC are likely to have some blowing snow due to gusty winds that will decrease around sunset this evening. Winds will pick up once again at KJAC and KRKS Tuesday. East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals Windy at KCPR and KCOD through the period. Other sites will see their winds decrease again this evening. VFR conditions will occur at the terminal sites through the period. Snow will occur over the Wind River and Absaroka mountains with lower ceilings and some mountain obscuration. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Issued AT 305 PM MST Mon Jan 13 2020 Snow will linger in the west today and increase again tonight with another wave. Snow will last until Tuesday afternoon with occasional burst of heavier snow with snow showers. Areas east of the Divide will be mostly dry. Winds, excluding in the basins, have been strong at times with gusts 45 to 55 mph. Winds will decrease overnight, but increase again Tuesday afternoon. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 8 PM this evening to 5 PM MST Tuesday for WYZ001-012>014-023>025. && $$ SHORT TERM...Troutman LONG TERM...Bourque AVIATION...Lipson FIRE WEATHER...Bourque
Area Forecast Discussion
National Weather Service Topeka KS
542 PM CST Mon Jan 13 2020 .UPDATE... Issued at 542 PM CST Mon Jan 13 2020 Dense fog has already developed along the NEB state line. Forecast soundings show the boundary layer becoming decoupled through the overnight with light and variable winds. With snow melt adding to the boundary layer moisture across the area, think the fog will only expand south and east overnight. Will be working on a dense fog advisory for the entire forecast area and hope to have it out shortly. && .SHORT TERM...(This evening through Tuesday) Issued at 338 PM CST Mon Jan 13 2020 This afternoon, high pressure is positioned over the Ohio River Valley with low pressure noted in the Front Range of the Colorado Rockies. This setup is allowing for strong southerly low level flow and WAA across the area. The above freezing temperatures have been chipping away at snow pack across eastern KS, which could be seen on visible satellite imagery where stratus had eroded over the eastern CWA. The stratus is expected to fill back in as a shortwave approaches the area from the west later this afternoon. Lift associated with the wave, combined with a nearly saturated column through about 5000 ft, as indicated by RAP and HRRR forecast soundings, should be enough to allow for sprinkles/light rain for a brief time as the wave moves over this evening. Into tonight, winds will subside and a weak front will move through the area. Fog is expected to develop again tonight due to moist grounds following the weekend`s winter storm, and light winds. Models are showing a drying of the low levels tomorrow morning, which should finally allow for more widespread sunshine across the forecast area. Highs tomorrow are expected to reach the low 40s north to near 50 degrees in our southern counties. .LONG TERM...(Tuesday night through Monday) Issued at 338 PM CST Mon Jan 13 2020 A surface low will strengthen in the Front Range late tomorrow and eject into the Plains early Wednesday. That low looks to work across KS and into MO by sunrise Wednesday. Forecast soundings are showing weak lift and a lack of deep moisture with this system so I am going with a dry forecast for now. CAA will occur through the day Wednesday in the wake of the low, so a standard diurnal warming trend may not be realized during the afternoon. Thus, temperatures will likely remain in the 30s and low 40s most of the day. A 1048mb surface high will then slide out of Canada and settle over the Midwest on Thursday. This will allow for some much cooler weather. Temps in the AM could be in the single digits and low teens before only warming into the 20s to near freezing during the afternoon. The next system of interest will be moving onshore over the western US Thursday, and will approach the region on Friday. Theta-e advection will occur ahead of the wave late Thursday and early Friday. As the system approaches, large scale ascent will occur and precip will become likely area-wide by very early Friday. Surface temps in the AM should be below freezing with the cooler airmass still in place, but soundings are showing a slight warm layer between 850mb and 750mb. This would lead to mixed precip in the form of sleet/freezing rain before temps warm to above freezing later in the morning. Total QPF is currently forecast to range from 0.50" to 1.0" across the CWA. This system will be one to watch through the week for the possibility of winter weather early followed by a decent rain event. Drier conditions are then expected through the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday) Issued at 542 PM CST Mon Jan 13 2020 LIFR conditions are expected to develop with forecast soundings decoupling the boundary layer and snow melt adding to the boundary layer moisture. Think dense fog and should expand south and east through the night, eventually breaking up during the late morning Tuesday. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Wolters SHORT TERM...Teefey LONG TERM...Teefey AVIATION...Wolters