Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/23/20

Area Forecast Discussion
National Weather Service Binghamton NY
1027 PM EDT Sun Mar 22 2020 .SYNOPSIS... An area of low pressure will bring snow and and possibly a mix of snow and rain to our region starting early tomorrow morning through tomorrow evening. Accumulating snow is expected area- wide, but especially across the higher terrain of the Catskills and Poconos. After a brief break in the weather on Tuesday, another system will bring a chance for more snow or rain on Wednesday. && .NEAR TERM /THROUGH MONDAY/... Moisture was very efficient in mixing out late this afternoon. As a result, RH values have fallen quite a bit over the past few hours. Adjustments with the evening updates included raising temperatures slightly and lowering dewpoints. The dry airmass currently in place is looking more likely to limit the potential snow overnight. With the drier trends the HRRR, RAP and NAM are showing a much weaker round of snow toward morning now. Also, a dry slot is looking more pronounced in the morning hours which should result in temperatures warming more rapidly in the morning. As a result, snow totals have been lowered across most of the region. 245 PM Update... Have made some changes to the winter weather headlines for the afternoon forecast update. The winter storm watch has been converted to a warning for Delaware and Sullivan Counties. Also, a new winter weather advisory has been issued for Southern Oneida County in NY and Wyoming County in PA. Overall, model guidance has not changed much with the 12Z suite. The NAM is still the most aggressive model with this system, with heavy snow in the Eastern Catskills and more widespread accumulating snow across the entire region. Very dry air is in place over the region with single digit to low teen dew points just about area-wide this afternoon. This dry air will be key as WAA/overrunning precip pushes in from the SW after midnight tonight. The dry air should hold and delay precip until early Monday morning, and evaporational cooling should be enough for precipitation to start as all snow everywhere tomorrow morning. Southern stream short-wave moves in from the Carolinas to the Delmarva coast tomorrow morning and where this wave phases with northern stream wave (that brings initial shot of snow) will be key on how much snow will fall in our CWA later Monday afternoon. The later it phases, as GFS has had, then the further east heavy precip will fall. NAM has it phasing earlier, and tracks surface low much further west, hugging the coast and then tracking just south of Long Island. Euro and Canadian are fairly close to the NAM solution, but keeps the heaviest band of snow near the Eastern Catskills to just east of our area. Temperatures are also going to very important for total snowfall accumulations tomorrow. Dynamic cooling will keep precip all snow tomorrow afternoon under heavy mesoband of snow, but where exactly this feature sets up is still uncertain at this time. Based on consensus from latest model guidance, our far eastern forecast counties have the best shot to get under a heavy band of snow. Snowfall rates within heavy band should be able to overcome warm surface temperatures as well, which will be important because of the high March sun angle. Elevation will also play a significant factor in the total of accumulating snowfall. Higher elevations should remain cold enough for all snow, but valley locations could mix with rain unless they get dynamic cooling from any mesoband that may form. Therefore, expect snow to eventually mix with and change over to rain, especially areas west of I-81 and in the valley locations by late Monday morning. However, areas east of I-81 (especially the higher elevations) that could get under heavy band of snow, should stay cold enough to remain all snow through the evening. Therefore, it is across these areas where we have went with a winter storm warning. Sullivan and Delaware counties in NY is where the highest snow accumulations will likely occur. 5-10 inches of snow is possible in the mountains with the heaviest snow expected during the afternoon and early evening across these areas. Elsewhere, Winter Weather Advisory for the Poconos, and several counties in Central New York and along I81 corridor. Across these areas, generally 1-3 inches of snow is possible in the valleys, with 2-5 inches possible at the higher elevations. Any counties not in the Advisory or Warning will likely only get a 1 - 2 inch slush and likely less in the valley locations. Coastal low pulls east Monday night and snow will come to an end from west to east. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... 350 PM update... Get a brief break in the weather on Tuesday, but next system will quickly push in by early Wednesday morning and persist through the day on Wednesday. The track of this system will be to the south once again and a very similar scenario to what we will see tomorrow. Basically a low tracks up the Ohio Valley, but energy transfers to the coast Wednesday afternoon as Coastal low quickly develops and intensifies. Model guidance still has quite a bit of spread between solutions this this system too. Basically, once again, temperatures and push of warm air aloft northward will determine if we see a snowstorm, or a cold rain. Euro is most concerning at this time, with heavy snow falling across large portion of the region. Meanwhile the NAM and GFS are warmer solutions with much less widespread snow and more mixing. Also, heaviest precipitation will be falling during the daytime hours once again, so snowfall rates will have to be intense to see accumulation. Due to differences in the guidance, going to stick with mostly a rain/snow mix across most of the region for now. Eastern Catskills have the greatest chance to see accumulating snowfall with this system, but will have to continue to see how the models trend over the next couple days, as widespread accumulating is not out of the question. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... 328 am update... Low pressure system and rain/snow will be pulling out of the area to the east Wednesday night as weak high pressure builds in across wrn/central NY. Mild overnight/Thur morning temperatures in the 30s are expected as the dry weather persists into late Thur morning. The overall synoptic flow becomes quasi-zonal for a period late this week which will create a very uncertain forecast in terms of when precipitation is expected and also wreak havoc on p-type/thermal profile forecasts. Model guidance continues to indicate a series of fast-moving weak waves rolling across the Northeast Wed night through Friday...although the threat for significant precip is not expected and any of these waves will be fast-moving. A better chance of precipitation...likely in the form of rain...will arrive by the weekend as the pattern amplifies and a sufficient amt of moisture is drawn up from the south and entrained into a developing low pressure system that is currently progged to move across the Great Lakes through the Northeast. Temperatures late this week are expected to remain on the mild side with highs in the 40s and lower 50s...and overnight lows in the 30s. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... 745 pm update... VFR conditions will dominate through 05Z. After that an initial period light snow moves through from the SW between 06Z and 11z causing cigs and vsbys to lower to MVFR or perhaps brief fuel alternate. There will be a break in the steady snow, with just some snow showers around from 11-15z Monday...during this period expect borderline VFR/MVFR conditions. Then, another steadier round of precip (snow-rain mix) moves in, starting between about 14-16z Monday. This will bring conditions back down to MVFR or fuel alternate rather quickly. After 18-20z, a combination of rain, snow, and fog is forecast to bring widespread IFR or Alternate Minimum conditions to all of our TAF sites. The best chance for precip to remain mainly or all snow through the day will be at KRME, KBGM and possibly KAVP. The other taf sites (KELM, KITH and KSYR) will likely go over to light rain during the afternoon...although a few wet snow flakes could still mix in at times. East-southeast winds increase to 10-20 kt overnight, continuing into Monday morning. Winds then diminish under 10 kts by late Monday afternoon, becoming easterly or variable. Outlook... Monday evening and night...Lingering drizzle or light snow in the evening. CIGs likely remaining IFR or fuel alternate much of the time. Moderate to high confidence Tuesday...Lingering clouds and restrictions in the morning, then partial clearing possible later in the day. Low confidence. Wednesday...Another round of rain/snow mix possible. Restrictions likely. High confidence. Thursday through Friday...Mostly VFR expected. Low chance for brief scattered rain showers. Moderate confidence. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...Winter Weather Advisory from 3 AM Monday to midnight EDT Monday night for PAZ039-040-043-044-047-048-072. NY...Winter Weather Advisory from 3 AM Monday to midnight EDT Monday night for NYZ009-036-037-044>046-056. Winter Storm Warning from 5 AM Monday to midnight EDT Monday night for NYZ057-062. && $$ SYNOPSIS...MPK NEAR TERM...MPK/MWG SHORT TERM...MPK LONG TERM...BJT AVIATION...MJM/TAC
National Weather Service Hastings NE
657 PM CDT Sun Mar 22 2020 .SHORT TERM...(This evening through Monday) Issued at 302 PM CDT Sun Mar 22 2020 As was anticipated, most of today`s precipitation turned out to remain mostly in north central KS and far southeastern NE counties of the CWA, and turned out to be mostly, if not all liquid. This occurred from the southern stream influence of a split flow regime. As a low-amplitude wave arrives within the northern stream, MUCAPE will be weakening as the evening/night wears on, and by the time the mid-level trough moves arrives this evening, instability will be weakening by the time it reaches the CWA, but just enough instability to keep thunder in the forecast tonight for anticipated isolated to scattered thundershowers, but strong storms are not anticipated. Both HRRR and SREF indicate a good chance of some fog around tonight with moisture increase ahead of the trough that will be moving through late tonight into early Monday morning, so I will likely keep mention of fog in the forecast, and if later runs indicate an uptick in fog, I might mention locally dense. Still quite a spread for temperatures tomorrow between numerical models. The NAM seems to want to hold onto lower stratus, keeping our high temperatures down to around 50 in the tri-cities, with GFS MOS giving us highs near 60 with less cloudiness. I might tend toward the cooler solution for Monday, seeing how models seem to have overestimated a bit of how warm we were to get today, or at least split the difference as there should be some clearing after the trough passes. .LONG TERM...(Monday night through Sunday) Issued at 302 PM CDT Sun Mar 22 2020 Progressive flow continues, although cold troughing in the west establishes by mid-week and puts us within southwest flow, which should bring milder temperatures in general, except for Thursday behind a cold front that passes through Wednesday night, and even then, temperatures will be seasonably cool with highs mainly near 50 to the mid 50s. Frequent small chances of precipitation look on tap for the long term, with an isentropic event for Thursday night looking like the best chance of measurable precipitation. Precip type looks like mostly rain in the long term, but a few flakes of snow are not out of the question if precip falls at the coldest part of the night, but even then, does not look like a large amount for now. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday) Issued at 622 PM CDT Sun Mar 22 2020 Some passing mid level clouds this evening are associated with a dissipating line of convection approaching the terminals from the west. Once this line moves across the area and temperatures drop...expect winds diminish...with some dense fog developing near the Missouri river valley and spreading west after midnight. Could see some dense fog locally by morning...but kept vsbys near 1SM at KEAR and slightly lower at KGRI. Along with the fog... expect IFR CIGS to develop at both terminals by sunrise... eventually scattering out by late morning. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...Heinlein LONG TERM...Heinlein AVIATION...Rossi
Area Forecast Discussion
National Weather Service Green Bay WI
633 PM CDT Sun Mar 22 2020 Updated aviation portion for 00Z TAF issuance .SYNOPSIS... Issued at 243 PM CDT Sun Mar 22 2020 Fairly quiet early spring weather with warming temperatures will continue through the middle of the week. The potential for more active weather will increase for the latter half of the week and into next weekend. The positive upper height anomaly near Alaska will persist for the next several days, then begin to retrograde westward. Downstream, the flow across North America will remain split early in the period, but tend to consolidate during the latter part of the period as a large scale trough settles into the Canadian Archipelago. The forecast area will remain primarily between the branches of the split early in the period, resulting in just scattered/light precipitation events through mid-week. The potential for significant precipitation will increase thereafter, likely resulting in AOA normal amounts for the period. Temperatures will range from near to modestly above normal. && .SHORT TERM...Tonight and Monday Issued at 243 PM CDT Sun Mar 22 2020 The latest RAP analysis and satellite/radar imagery show Wisconsin positioned between high pressure over Quebec and a weak cold front located over the Dakotas. Under flattened troughing aloft, weak shortwaves are moving east across Missouri/Illinois with light precipitation extending as far north as Des Moines and Bloomington. More spotty light precip exists along and ahead of the front with some help from additional weak shortwave impulses. Some of these returns may clip north-central WI late this afternoon. As this front moves across the area tonight, light precip chances are the main forecast concern. Tonight...Northern Wisconsin will remain positioned between shortwave activity passing by north and south of the region. Widespread precipitation is not expected, but expect clouds to return to the area where skies cleared this afternoon (central WI). Additionally, light snow showers may continue to clip north- central WI in a weak warm advection pattern through the evening before the weak front arrives overnight. Light wintry precip chances will expand across central and north-central Wisconsin along the front, and may result in a minor dusting. The snow may mix with spotty light freezing drizzle as models peel out mid- level moisture late. Mild lows in the middle to upper 20s. Monday...The weak front will continue to move east across northern WI and lose definition in the process. As a result, think any lingering light wintry precip (snow or freezing drizzle) will likely diminish in the morning. Then expect a slow decrease in cloud cover for the rest of the day. North-central WI will have potential to see more sunshine in the afternoon than further south. High temperatures will be warmer and range from the low to mid 40s. .LONG TERM...Monday Night Through Sunday Issued at 243 PM CDT Sun Mar 22 2020 There has not been much change to the expected weather scenario/ forecast since yesterday. Subtle features affecting the area the next few days will result in low-end PoPs at times, but no precipitation of real significance. A quick-hitting but more significant round of precipitation is possible Wednesday night if a frontal wave develops and rides northeast through the area as a cold front slides through the region. The overall upper flow is relatively flat, so the models are struggling with the strength of the wave and the timing and location of the precipitation--which has implications on precipitation type. This situation could result in advisory criteria snows in the north (12Z ECMWF), but this is a very low-predictability set-up. Will continue to mention in the HWO, but hold off on hitting it any harder for now. The large scale set-up is a little more stable and favorable for a cyclone to affect the area Friday night into Saturday. But that is far enough out that there are still considerable differences in the track and thermal fields among the models. Will continue with just a mention in the HWO for now. && .AVIATION...for 00Z TAF Issuance Issued at 632 PM CDT Sun Mar 22 2020 A period of VFR clouds are expected this evening across the area as the sun sets. However, another weak system will arrive overnight in central WI, bringing back MVFR CIGS, possibly as low as a brief IFR. Some flurries or light snow are possible with this system for RHI, AUW, and CWA. The main item of uncertainty is whether any light snow or flurries show up overnight given the abundant dry air in place and the lack of strong forcing this this system. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS.......Skowronski SHORT TERM.....MPC LONG TERM......Skowronski AVIATION.......Kurimski
Area Forecast Discussion...CORRECTED
National Weather Service Grand Rapids MI
827 PM EDT Sun Mar 22 2020 LATEST UPDATE... Update/Aviation .SYNOPSIS... Issued at 137 PM EDT Sun Mar 22 2020 - Slick roads possible tonight - Period of rain Tuesday Night - Above normal temperatures mid week - Strong storm possible for the weekend && .UPDATE... Issued at 747 PM EDT Sun Mar 22 2020 It would seem to me our overall forecast is on track. However I am thinking we may see a little more than we were earlier thinking. I could see and area of 2 to 3 inches between I-94 and I-96 having fallen by sunrise Monday. The precipitation has been nearly all snow at most of the reporting stations across Illinois, Indiana and extreme southern Michigan this afternoon into early this evening. There have been several stations reporting moderate snow over the past few hours and LSR`s from CHI show 2 to 3 inches having fallen in many places just southwest of Chicago, near Joliet. The trend in the HRRR storm total precipitation since 18z has shown a trend farther north with the heaviest snow area. The 22z run has .20 to .25 inches of water equivalent precipitation falling across Allegan, Barry and southern Ionia Counties. This would lead to 2 to 3 inches in that area. What will help that 2 to 3 inches of accumulation is that temperatures fall quickly to freezing once the snow starts (based on surface obs to our south where the snow started already). Given the snow will be falling at night and dew points are in the low 20s over our southern CWA, it would seem the snow will have little problem sticking to the grass. I updated our snowfall amounts to reflect this change. I am still on the fence for an advisory through since I do believe most the accumulations will be on grassy surfaces and not on the roads. && .DISCUSSION...(This evening through next Sunday) Issued at 137 PM EDT Sun Mar 22 2020 - Slick roads possible tonight As the precipitation moves in later this afternoon and evening...forecast soundings support a rain/snow mix at the onset. As the precipitation becomes steadier a transition to all snow is about midnight. High res guidance shows the strongest lift this evening...which then tapers off later tonight. Thus the steadiest precipitation should be gone by the Monday morning commute. Surface temperatures may struggle to fall below freezing this evening. Most guidance shows below freezing temperatures after midnight. Thus any snow should be melting as it falls this evening. Then tonight as it is winding down some icy spots may combine with slushy conditions to lead to some impacts. Bridges and overpasses look to be most impacted. The area south of Interstate 96 will likely see the most qpf being closest to the Ohio Valley low track. - Period of rain Tuesday Night Another wave of low pressure tracks steadily up the Ohio Valley then. While this track will also be south of Michigan...the atmosphere will not be as cold as tonights event. Thus this one is looking more like a rain event. Overall qpf is shown to be limited so no impacts are predicted from this event. - Above normal temperatures mid week A short period of warm air advection develops on Wednesday. With the 925 mb thermal ridge of 6 to 8 deg C passing through Wednesday afternoon/evening...this should support Highs in the 50s. A cold front will be moving in from the west by Thursday so the warmup will be limited. 925 mb temperatures drop off to 1 to 4 deg C by 00z Fri on the backside of the front. - Strong storm possible for the weekend We will need to monitor this potential storm closely. Guidance is in relative agreement in showing a surface low deepening as it tracks northeastward through the Great Lakes Region. Aloft the system goes negatively tilted...which usually spells impacts. Wind is of concern as the pressure gradient is shown to tighten up considerably Friday night into Saturday. Some snow is possible near the onset Friday night...mainly over northern zones which includes the communities such as Harrison and Baldwin. Overall though this system is forecasted to be a rain event. Some Gulf moisture will get drawn into the storm so pockets of heavy rain are possible. The latest High Res Euro does show instability...thus the thunder risk is not zero. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 747 PM EDT Sun Mar 22 2020 I expect solid IFR and some LIFR over most of our TAF sites, most of the night due to snow. MKG will be on the north edge of the snow and may not be as impacted as the other TAF sites. The lowest conditions for just about all the TAF sites will happen in the 02z to 08z time frame. Visibilities will rapidly improve once the snow ends around sunrise. However I expect MVFR cigs to linger most of the daytime hours of Monday. Expect moderate to heavy in cloud icing through about 15,000 ft tonight while the snow is falling. The heaviest icing is expected between 10,000 ft and 14,000 ft. The area of icing should largely be east of the TAF sites by 16z Monday. && .MARINE... Issued at 137 PM EDT Sun Mar 22 2020 Overall winds and waves will remain below hazardous levels through much of the week as the pressure gradient remains relatively weak and the the air will be warmer than the lake. Later in the week a risk for bigger storm exists and that could result in impacts. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && $$ UPDATE...WDM SYNOPSIS...MJS DISCUSSION...MJS AVIATION...WDM MARINE...MJS
Area Forecast Discussion
National Weather Service Wichita KS
658 PM CDT Sun Mar 22 2020 .SHORT TERM...(This evening through Thursday night) Issued at 246 PM CDT Sun Mar 22 2020 Shortwave that produced lasts nights rain showers has shifted east into MO. But even as the shortwave shifted east, low level moisture and weak isentropic upglide continues over most of southern KS and the Flint Hills. This has led to pesky areas of drizzle and fog moving across southern and southeast KS. Latest RAP guidance suggests that this drizzle and fog will wane or end from west to east as the late afternoon progresses. Could still see the drizzle linger into the evening hours, especially for areas over SE KS and the Flint Hills, so will keep this mention in for now. The next shortwave in the zonal flow will quickly move across the southern Rockies into the plains by Mon afternoon into Mon night. A low pressure area is expected to develop over extreme SW KS and the OK panhandle by Mon evening, ahead of this shortwave. Latest model trends suggest that this system is coming into the plains slower than previously thought, which changes the timing of the strong/severe storm threat. Also the GFS and NAM/WRF are coming around to the ECMWF solution of taking this low pressure area further south, along and just south, of the Kansas/Oklahoma border, as it treks east. This more southerly track suggests that surface based instability will be delayed and remain further south across central OK, limiting the surface based severe weather chances across and KS and especially southern KS. But, as the low moves east, strong warm advection, will pull elevated instability N-NE, just to the east of the low, for the evening and overnight hours Mon into southern KS. Bulk shear and directional shear still looks impressive, as this system moves across, with steep elevated lapse rates across most of southern KS for the late evening into the overnight hours on Mon. Most unstable CAPE values still climb into the 1000-1500 j/kg range, especially after 03z/Tue and certainly by 06z/Tue. This would suggest that the strong to severe storm chances will be delayed until the late evening and overnight hours. Directional shear still supports discrete supercells will still be possible, but a strong inversion below 850h suggests the supercells will be elevated with large hail (dime to possibly golf ball size) now looking like the main severe weather impact. Cannot completely rule out a surface based supercell further south in OK, racing NE, possibly leading a a very small tornado chance. Dry and mild conditions are expected for the middle of the week, with max temperatures climbing back above normal as downslope flow dominates the weather pattern. Medium range models show a weak cold front will push across the area late Wed night or early Thu. Consensus suggests a dry frontal passage as moisture will be limited. The frontal boundary looks to slow or stall across southern KS late Thu night. Overrunning moisture associated with another weak shortwave in the zonal flow, may lead to a chance of showers and embedded storms for late Thu across southeast KS as the moisture overruns the stalled boundary. Ketcham .LONG TERM...(Friday through Sunday) Issued at 246 PM CDT Sun Mar 22 2020 Lots of uncertainty on how the end of the week will play out, as both the GFS and ECMWF show a vigorous shortwave making its way across the plains. But the timing remains uncertain, with the ECMWF sweeping out precip chances by Fri, but the GFS is deeper and slower with the system, with precipitation lingering Fri night thru Sat night. Ketcham && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 658 PM CDT Sun Mar 22 2020 Some concern for lower vsbys in radiational fog where partial clearing is possible over central Kansas tonight, then perhaps some stratus build-down over southern Kansas. Either should result in MVFR vsbys with potential for IFR/LIFR over central Kansas. Stratus cigs lowering to IFR are expected early Monday morning, before lifting/improving to MVFR by early afternoon. KED && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 42 64 52 68 / 10 10 90 10 Hutchinson 38 62 49 66 / 10 10 100 10 Newton 39 63 50 65 / 10 10 90 10 ElDorado 42 63 51 66 / 10 10 90 10 Winfield-KWLD 45 64 53 70 / 10 20 90 10 Russell 35 63 45 67 / 10 10 90 10 Great Bend 35 62 46 68 / 10 10 70 0 Salina 36 62 48 65 / 10 10 90 20 McPherson 37 62 48 64 / 10 10 90 10 Coffeyville 46 65 55 71 / 20 10 90 30 Chanute 44 63 53 67 / 20 10 90 40 Iola 42 62 52 66 / 20 10 90 50 Parsons-KPPF 45 64 54 69 / 20 10 90 30 && .ICT WATCHES/WARNINGS/ADVISORIES...None. && $$ SHORT TERM...Ketcham LONG TERM...Ketcham AVIATION...KED
Area Forecast Discussion
National Weather Service Louisville KY
940 PM EDT Sun Mar 22 2020 .Forecast Update... Issued at 940 PM EDT Sun Mar 22 2020 Initial wave of precipitation continues to advance eastward across east-central KY this evening. The rain has ended west of I-65, but the largest concentration of showers over the next few hours will be in areas bounded by I-65, I-75 and south of the Bluegrass Parkway. These showers should exit the region by 1100 PM EDT. In the wake of the rain showers, we`ll see continued low clouds and patches of fog/mist across the region. A secondary surge of moisture is likely to develop across west-central TN this evening and then move northeastward overnight. Last few HRRR runs show best chances of overnight rain showers to be southeast of a line from roughly Bowling Green to Lexington. Current forecast has this well in hand, but we did make some updates to the Grids. First, we lowered PoPs for the next few hours west of I-65, while keeping higher PoPs over our SE sections. Based on the anticipated additional showers developing across W/C TN, have kept chance PoPs going for the overnight period with highest chances down in the Lake Cumberland region. && .Short Term...(This evening through Monday) Issued at 235 PM EDT Sun Mar 22 2020 A weak surface trough draped from the eastern Great Lakes through the Ohio Valley to the Red River will move little tonight. Scattered light rain showers this evening will become more widespread overnight as an upper level disturbance comes in from the west and interacts with the boundary. Temperatures shouldn`t drop more than a few degrees under the thick blanket of clouds and with light winds shifting from east to south to west over the course of the night. The upper disturbance and surface trough will move off to the east Monday, allowing the showers to taper off from west to east in the morning. With not much change in thicknesses, plenty of clouds, and a northwest breeze, will go on the cool side of guidance for high temperatures tomorrow afternoon a few degrees below normal. .Long Term...(Monday night through Sunday) Issued at 309 PM EDT Sun Mar 22 2020 *Monday Night* High pressure will likely be over the upper Ohio Valley Monday evening, but will quickly push eastward toward the Appalachians and surface flow will veer from northerly to easterly by Tuesday morning. Meanwhile an area of low pressure will eject into the southern Plains Monday night and begin quickly moving toward the Ohio Valley. This will set the stage for some active and potentially severe weather. *Tuesday* Most guidance shows the surface low slightly deepening as it traverses across the Plains and into the Missouri Valley. A surface warm front ahead of the low will begin lifting into Tennessee after sunrise Tuesday and eventually come close to the Kentucky border by late Tuesday afternoon. An ongoing broad band of precipitation along and ahead of the warm front Tuesday will move into the region after sunrise and persist through most of the day. While embedded thunderstorms will be possible within this broad band of precipitation, a stout inversion near the surface should keep the severe threat near zero during most of the daylight hours. It`s not until the late afternoon and especially evening/overnight hours that a severe threat begins to increase for southern parts of the region due to the warm front lifting into southern Kentucky. Storms generally near and south of the warm front will transition from elevated to surface based due to an increased flux of T/Td`s within the WAA regime. There will be a couple of focus areas for surface based convection to develop: (1) the pre-frontal trough, and (2) along the cold front. The pre-frontal trough looks to pass through during the late afternoon hours, while the cold front lags behind anywhere from 6-9 hours, depending on what model you prefer. Deep layer and low level shear will be strong, but instability continues to remain a question mark. Some higher-res guidance (i.e., NAM) show modest amounts (500-1,000 J/KG) developing over south- central Kentucky. Global models (i.e, GFS, ECMWF) tend to result in more meager amounts (<500 J/KG). Regardless of which model ends up verifying, all of them generally show poor lapse rates with long, skinny CAPE profiles. The overall convective details this far out remain a bit fuzzy, but surface based storms that form in this environment will be potentially capable of all severe hazards, including tornadoes, assuming the instability present is enough to sustain it (which could be a big assumption depending on how models verify). If any isolated surface-based supercells develop, particularly along the pre- frontal trough in the late afternoon across northern TN and southern KY, they will be especially concerning, as surface winds ahead of the trough will be generally backed out of the S/SE and result in long, clockwise curved hodographs supportive of low level mesocyclogenesis and potential tornadoes. The close proximity of the warm front during this time will also contribute to localized helicity for storms to potentially ingest. Storms that develop later in the night along or near the cold front will still be working with strong low level shear, so those will also have to be watched closely, even if storm mode becomes linear. At this time, there still remains some uncertainty as to how far north the warm front will lift, which will ultimately impact our severe weather threat timing and chances. Areas south of the I-64 corridor look to have some chance for severe weather, with the best chances across southern KY near the TN border. Should the warm front lift slower and not push into south-central Kentucky until after dark, it`s likely that any severe threat would hold off until the overnight hours ahead of the cold front. *Wednesday and Beyond* The cold front and associated storms should clear out of the region by Wednesday morning near sunrise. Dry conditions may be brief, though, as a stalled/nearly stationary boundary could set up near or over the region beginning late Thursday and last through the weekend. Still a lot of details to be worked out with this setup, as models vary on the overall temporal and spatial details. Will use a broad coverage of PoPs for now to highlight rain potential, with the highest chances focusing on Fri-Sat. && .Aviation...(00Z TAF Issuance) Issued at 735 PM EDT Sun Mar 22 2020 Batch of light rain along the I-65 corridor will continue to move eastward this evening. A short period of rain showers is expected at BWG/SDF and LEX this evening but should largely clear those terminals by 23/02-03Z. After that, we expect ceilings to lower overnight into the IFR range. Guidance hints at some additional showers and quite a bit of mist overnight, so its possible that visibilities may drop to 2-3SM in places overnight with light and variable winds. Toward Monday morning we`ll see winds shift around to the west and northwest with a slow improvement in ceilings through the morning hours. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update.......MJ Short Term...13 Long Term....DM Aviation.....MJ
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
923 PM CDT Sun Mar 22 2020 .UPDATE... 923 PM CDT Have continued to trend upward with snow accumulations this evening with a report of over 5 inches just outside of Coal City and many reports of >4" along the I-80 corridor in IL, including the Joliet area. Regional radar imagery shows a band of moderate to possibly heavy snow lifting north toward the I-88/290 corridors. Up until shortly after sunset, reports indicated that area roads were generally fairing quite well, despite the heavier than expected totals. Since sunset, have seen reports of quickly deteriorating road conditions. Considered a short fused winter weather advisory, but given the meaningful snowfall should be ending in the next couple hours, opted to cover it with an SPS. Once snow ends, expected overcast conditions to linger. Can`t rule out stratus building down to freezing fog or some patchy shallow ground fog developing, particularly where the snow will be quickest to end and where the heavier snow falls. Confidence is pretty low fog development, so just introduced some patchy freezing fog for now, but will brief the oncoming shift about potential fog concerns to monitor. Stratus is fairly extensive and given the light winds and moisture trapped beneath inversion, quite plausible many areas won`t see any sunshine tomorrow. The lack of expected lack of sunshine will probably result in temps cooler than going forecast for tomorrow, in particular over the deeper snow pack in the southern suburbs. Will begin the trend of lowering temps a bit tomorrow this evening, but suspect overnight shift may need to make further downward adjustments. - Izzi && .SHORT TERM... 232 PM CDT Through Tonight... Focus of the near term forecast remains on our late-March accumulating snowfall for late today and tonight. Amounts of generally 1 to 2 inches are expected across most of the heart of the forecast area by the time snow tapers off and ends predawn Monday. Some slushy accumulations are possible on area roads, especially this evening when snow is expected to be at its most intense. Early afternoon GOES water vapor imagery depicts a fairly vigorous mid-level short wave circulation across the lower Missouri Valley, tracking east-northeast toward IL/IN. Precipitation has blossomed and spread into the region during the day, in response to broad southerly low-level return flow and its associated warm/moist advection and isentropic ascent. In the low levels, retreating high pressure has left east-southeasterly low level winds and temperatures which have struggled into the mid-30s beneath increased mid/high cloud cover. As expected, a mix of light rain and snow was being reported along the leading edge of the advancing precipitation shield, but has quickly turned to snow as intensity increases and low level dry air cools to the wetbulb temperature. Initially, the best isentropic ascent on the 290-300 K surfaces appears to be focused across the south/southeastern parts of the cwa through late afternoon, though with time a modest deformation zone (already developing from southern IA into western IL) shifts across the northern 2/3 of the forecast area into this evening. Broad ascent, aided by upper divergence within the left exit region of the upper jet streak and a layer of steep lapse rates (7.5-8.5 C/Km) above 600 mb should expand the precip shield and produce a prolonged period of light-moderate snow through the evening and early overnight hours. Some frontogenetic banding is evident in RAP forecasts during this period, though it looks to be somewhat transient. The better forcing eventually shifts east of the forecast area in the pre-dawn hours, as the mid-level trough axis transits the area. Overall, forecast trends remain fairly steady, with only a continued slight northward shift to model QPF axis this evening. Combination of better early forcing south, but a prolonged more moderate period of forcing a little farther north still looks to produce a fairly wide swath of 1 to 2 inch snow amounts. Expect that this will be most likely on grassy and elevated surfaces, while roads (with a few current road surface temps reported in the 40s) may see only some lighter slushy wet accumulation this evening during the time of greatest snowfall intensity. Surface temperatures should hover near the freezing mark or just above through much of the event, with low levels saturating near freezing. Weak surface high pressure ridge develops into the area from the west toward morning, as the mid-level short wave exits the region. The combination of wet snow on the ground and a saturated shallow boundary layer, combined with winds becoming light and variable late tonight, will likely result in lingering low cloud cover and some areas of fog which may persist into Monday morning. Ratzer && .LONG TERM... 252 PM CDT Monday through Sunday... A fairly active weather pattern is expected to persist through the coming week, with largely zonal upper flow hosting a series of generally minor amplitude short wave disturbances. Guidance does remain in good agreement in amplifying an upper trough across the western states later in the week, which may produce a more robust storm system for our region Friday into Saturday. Weak surface high pressure will be across the area Monday, in the wake of the snow producing system currently moving into the area. Cloud cover and some fog will likely linger during the morning hours, though some decrease in cloud cover is possible by afternoon as weak ridging aloft produces some subsidence and drying above the shallow boundary layer. Depending upon the extent of cloudiness by afternoon, guidance temps in the mid-40s may be a bit optimistic, and cooler temps are likely particularly along the Lake Michigan shore where winds will likely turn onshore in the afternoon due to the weak surface pressure gradient. The first in a series of minor amplitude short waves to traverse the Midwest is progged to approach the region late Monday night and transit the area Tuesday, with a chance of rain. Models depict a decent surface low reflection across the Ohio Valley with this initial wave, with sufficient forcing and moisture available to support likely pops. Another slightly weaker disturbance is depicted to affect the region later Wednesday and Wednesday night, with a cold front trailing across the forecast area by Thursday morning. Thermal profiles during both of these should be mild enough to support rain as the p-type, with daytime temps in the 40s to low 50s and nighttime mins in the 30s to low 40s. The cold front then lays out off to the south of the forecast area into Friday, and may continue to be a focus for additional light rain production with any ripples which traverse the fast westerly flow aloft. Precip chances will likely ramp up more substantially with the approach of the late-week deeper trough. There is good agreement between the ECMWF and Canadian medium range guidance (and their ensembles) in developing a deep surface low (less than 990 mb) across northern IL or southern WI by Saturday morning. This would support a period of greater rainfall and potentially some thunder for the region. Ratzer && .AVIATION... For the 00Z TAFs... 638 PM...Forecast concerns include... Light snow through early morning. Possible fog Monday morning. Lifr/ifr cigs Monday morning. Light snow will continue across the entire area this evening... ending from west to east overnight. Visibilities had dropped into the 1/2sm range for a few hours but as the better support shifts east...visibilities are likely to remain around 1sm with still some potential for 3/4sm at times. Cigs have been somewhat variable but should lower to lifr this evening and continue through mid morning Monday when cigs will slowly lift through ifr and into mvfr. Cigs may begin to scatter out Monday afternoon but confidence is low. As the snow ends overnight...there will be a potential for fog to develop. Confidence is only medium but added tempo for vis under 1sm and it is possible dense fog develops...especially in more rural areas. Trends will need to be monitored for possible lower vis which also may become prevailing. Light southeast winds will become light and variable overnight and then shift light northerly before sunrise. Wind directions will turn back northwesterly by midday and then possibly to southwest in the afternoon. Depending on how much clearing occurs in the afternoon...there may be a lake breeze in the afternoon which would shift winds easterly at ord/mdw. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion...UPDATED
National Weather Service Shreveport LA
1006 PM CDT Sun Mar 22 2020 .UPDATE... Showers have decreased in coverage across most of the area, but are starting to increase in both coverage and intensity across Southern Arkansas and North Central Louisiana. The convection currently south of El Dorado AR helped to dissipate the dense fog from Shreveport east-northeast across Bossier and Webster Parishes. Visibilities have improved greatly in these areas, but dense fog can is being observed just across the border into Texas. Therefore, the Dense Fog Advisory will be maintained for now. Temperatures have already fallen below forecasted lows in many locations, so low temperatures were dropped by a couple of degrees areawide. As the fog and rain expand later tonight, and with the warm front moving northward, temperatures should hold fairly steady. Where the warm front passes, temps may actually rise a degree or two. PoPs were also adjusted, with a general decrease in most areas, especially the northwest and southeast corners, through the remainder of the overnight hours. Both the NAM and the HRRR continue to suggest a rather narrow band of showers will persist across East Texas and North Louisiana along and just south of Interstate 20 near the warm front. Updated products will be sent shortly. CN && .PREV DISCUSSION... /issued 738 PM CDT Sun Mar 22 2020/ UPDATE... See below for 00z Aviation Discussion. Visibilities have rapidly decreased in a corridor generally along or just south of Interstate 20 from Tyler TX to Minden LA. Several locations are already observing dense fog. The latest HRRR suggests the fog will expand across portions of East Texas, particularly in Wood, Smith, and Cherokee Counties in the next two to three hours. Therefore, a Dense Fog Advisory was issued for portions of the area through 09z Monday morning. Model guidance suggests visibilities should slightly from east to west during the early morning hours. CN AVIATION... For the 23/00z TAFs, IFR/LIFR conditions prevail at most TAF sites. Dense fog with visibilities at or below 1/4SM are affecting terminals along Interstate 20 in East Texas and Northwest Louisiana, and some expansion of the dense fog is likely across Texas early in the period. A band of showers moving northeast from Central Texas and into Northwest Louisiana will likely persist for much of the period and may expand northward during the overnight hours. Visibilities should improve by 23/15z, but IFR/LIFR ceilings will persist. The showers may slowly begin to taper off at most TAF sites by early Monday afternoon. CN PREV DISCUSSION... /issued 259 PM CDT Sun Mar 22 2020/ SHORT TERM.../Tonight through Monday night/ Well after an average of a half inch to inch of rainfall overnight and this morning, the calm or light and variable winds have only added to the formation of fog. An upper low moved overhead at daybreak, but did not pick up the stationary front to our south. The air is sinking overhead in the wake of the upper low and locking in the inversion for us once again with the thickest fog still in E TX where rain ended first. The warm front is drifting Northward and will get across I-20 during Monday. The surface and low level winds will still remain on the light side and more fog and showers for much of the area overnight and into the first half of Monday. Then this shower and thunderstorm activity will shift farther N into the later day. Temperatures will continue to slowly warm for most sites. Overnight Monday will see more improvement with the warm air able to hold more moisture, but we will also see and uptick on showers again, mainly N with another upper short wave on approach. /24/ LONG TERM.../Tuesday through Saturday Night/ On Tuesday, an upper level trough will move across the area ahead of an attendant dry line. Small rain chances will be possible for northern and northeastern sections as it does so. Then, on Wednesday, surface high pressure will traverse the region and move east for Thursday. At the same time, weak ridging aloft will move into the region on Wednesday and keep dry conditions over the forecast area through mid-day Friday. Rain chances will return by Friday afternoon for our western zones as the upper level ridge shifts east. Rain chances increase for Saturday as an upper level trough pushes a cold front through the area. There`s some disagreement on the timing of this next system but went with the slower solutions at this time. Relatively cooler conditions after the frontal passage on Saturday which will persist through the weekend. Overall, much of the extended, especially Wednesday through Friday, will be above normal. Guidance has backed off some of the early showings of near record high temperature values for the end of the week. Nonetheless, things do appear to be rather warm for the end of the first full week of Spring. /35/ && .PRELIMINARY POINT TEMPS/POPS... SHV 60 78 64 79 / 50 50 10 20 MLU 63 75 63 80 / 60 70 10 30 DEQ 51 69 59 80 / 30 30 70 30 TXK 53 70 62 78 / 50 30 50 30 ELD 53 71 61 79 / 60 60 30 30 TYR 58 78 64 81 / 30 30 10 10 GGG 58 77 63 80 / 40 40 10 10 LFK 64 82 65 82 / 30 20 0 10 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...Dense Fog Advisory until 4 AM CDT Monday for LAZ001>003-010. OK...None. TX...Dense Fog Advisory until 4 AM CDT Monday for TXZ124>126-136>138- 149>153. && $$ 09/05
Area Forecast Discussion
National Weather Service Topeka KS
605 PM CDT Sun Mar 22 2020 ...AVIATION UPDATE... .SHORT TERM...(This evening through Monday) Issued at 331 PM CDT Sun Mar 22 2020 Deep moisture associated with the upper trough exiting the Missouri Valley was east of the area early this afternoon though IR imagery indicates some deeper moisture remains in northern areas. Southerly winds in southeastern areas keeping modest low-level convergence going where some drizzle persists. Will continue with some drizzle mention for a few hours per recent RAP/HRRR. The trailing upper wave was giving rise to a scattered thunderstorms in far northwestern portions of Kansas where modest instability has developed. More stable conditions not far east should keep this activity from reaching the CWA. Stratus is again prevalent over the region with clearing in western Kansas rather slow. With modest wind fields in a weakening surface pressure pattern over wet ground, not seeing much reason for clearing and the potential for fog formation is certainly present though widespread dense fog potential appears low in this setup. Mixing increases somewhat Monday though from the southeast which keeps the lower levels moist. Have slowed the clearing trend and lowered temps a bit. .LONG TERM...(Monday night through Sunday) Issued at 331 PM CDT Sun Mar 22 2020 Monday night into Tuesday bring the main periods of interest in this forecast as the southern branch upper low off the California scoots east rather quickly and traverses the state late Monday afternoon into early Tuesday morning. Models continue to show notable differences in mid-level lapse rates and moisture depths for varying degrees of instability though effective shear and at least modest instability leads to elevated strong/severe storm potential. Much may depend on upstream convective trends and keep organized storms in check here. Best moisture convergence looks to push across central and eastern portions of the state which could lead to a swath of heavier precipitation across central and southern portions of local area. If this occurs, an isolated and minor flood concern could develop. Some late AM and afternoon clearing looks to take place though surface flow is again modest and of a northerly direction which could again lead to stubborn stratus. Southerly winds return Wednesday as a northern branch wave approaches though gustiness currently looks isolated and short- lived and RH values above 40 percent. Temps expected to reach back into the upper 60s to lower 70s. Lower levels look to remain too stable for much of any precip here with the frontal passage. Thursday`s highs fall back into 50s and 60s. Better precipitation chances return late in the week as the next southern branch wave approaches with seasonal temps into the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 605 PM CDT Sun Mar 22 2020 With the boundary layer saturated and subsidence behind the shortwave tonight, expect there is no place for the moisture to go overnight and this should lead to LIFR and possibly VLIFR conditions through Monday morning. Isentropic surfaces shows patchy drizzle could hang on for several hours this evening. Then fog is forecast to become more prevalent overnight. There is some indication from the RAP and GFS that the boundary layer will mix better Monday afternoon and improve CIGS. So will show some improvement late in the forecast period. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...65 LONG TERM...65 AVIATION...Wolters