Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/21/23

Area Forecast Discussion
National Weather Service Quad Cities IA IL
516 PM CST Mon Feb 20 2023 ...00Z AVIATION UPDATE... .SYNOPSIS... Issued at 316 PM CST Mon Feb 20 2023 A few high clouds are streaming across the area early this afternoon. A fast moving storm system has moved into eastern North Dakota by 1 PM and will move across the area tonight. Ahead of this storm system there were gusty southerly winds across the area of 10 to 20 MPH. At 1 PM, temperatures ranged from 40 degrees at Dubuque to 50 degrees at Moline and Mount Pleasant. && .SHORT TERM...(This evening through Tuesday) Issued at 316 PM CST Mon Feb 20 2023 Key Messages: 1. A cold front will move across the area tonight. Sprinkles are possible. Strong west to northwest winds will develop behind the front with gusts of 30 to 35 MPH. 2. Tuesday will be noticeably cooler. Discussion: The main forecast concerns were chances of precipitation and winds. Models are in good overall agreement however the CAMS and Canadian model want to bring showers or sprinkles into the area tonight. A fast moving storm system will pass to our north tonight and bring a strong cold front across the area. Moisture and lift are limited across the area however the HRRR, NAMnest and Canadian develop scattered rain showers or sprinkles across the area this evening. HRRR model soundings are most supportive of rain showers or sprinkles across southern Iowa and adjacent area of Missouri and Illinois. The other models are considerable drier in the lower levels of the atmosphere and produce no precipitation. Decided to leave any mention of showers or sprinkles out of the forecast. Additionally, behind the cold front, the pressure gradient increase as high pressure quickly builds into the area. This results in a nice rise/fall couplet that passes to our north. Mixing is expected to be shallow but the models and CAMs disagree on the depth. In general, winds of 15 to 25 MPH behind the front with gusts of 30 to 35 MPH are expected. Temperatures will drop behind the cold front as colder air moves into the area. Temperatures on Tuesday morning will range from the upper teens along the Highway 20 corridor to the upper 20s along and south of a Mount Pleasant to Galesburg line. High pressure will quickly move across the area on Tuesday resulting in winds quickly diminishing after sunrise. High temperatures on Tuesday will be about 10 degrees cooler with high temperatures ranging from the lower 30s along the Highway 20 corridor to the mid 40s in far southeast Iowa, northwest Illinois, and far northeast Missouri. Clouds will slowly increase and thicken through the day ahead of the next storm system. .LONG TERM...(Tuesday night through Monday) Issued at 316 PM CST Mon Feb 20 2023 Key messages: 1. Overall storm for midweek appears to be unchanged as far as impacts for the area. 2. Main questions yet to be answered are, do we see sleet from convection and how much ice do we get from freezing rain? 3. Colder temps Friday before moderating temps this weekend with chances for precip to start the weekend and new work week look possible. Discussion: Overall pattern remains unchanged from earlier forecasts. We find our area south of warm advection/FGEN band to start Wednesday. The upper level wave ejects out of Mexico towards the area eventually becoming negatively tilted. The deepening of this system will bring more WAA to the area along with moisture. As mentioned earlier, the track of this system remains very consistent. What is uncertain is how far south the freezing line gets. As far as ptype goes, the guidance has been consistent with the axis of freezing rain literally lying along the northern borders of the area in Dubuque, Delaware and Buchanan Counties. Freezing rain will be possible south of this line but the best chance for accumulating freezing rain will be located here. There will also be some sleet across this area, especially Wednesday evening into Thursday morning as steep lapse rates may lead convective updrafts and sleet production. If that occurs we could see rapid sleet accumulation. Confidence is low at this time that it will occur. As far as ice amounts go, with the uncertainty of where the freezing line will be have decided to continue the use of probability of exceedance graphics to provide the context. The 0.1 exceedance and 0.25 exceedance probabilities are unchanged as 50-80% looks likely for 0.1 and 20-40% for 0.25. At the end of the day a winter weather advisory is likely needed for portions of the area for this event. We still expect to have strong winds Thursday as the surface low moves through the area. Strong H85 winds of 50 to 70kts are possible. This could turn into gusts of 35 to 45 mph and we will likely need some wind advisory. These winds could cause issues with any ice on trees and could lead to power outages. As far as heavy rain goes the potential for this still exists. WPC excessive rainfall outlooks have southern portions of the CWA in a slight risk for flash flooding. The NAMnest does have some showers and possible storms with high PWATs. Will have to keep an eye on this threat as go forward. Looking at FFW guidance we need 2 inches in 3 hrs to FFW and 2.5 inches in 6 hr to FFW. Some guidance has 6 hour guidance near 2 inches, so there is a threat and we would need better convective rains. CAMs in the next day or so will help discern this threat better. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 513 PM CST Mon Feb 20 2023 VFR is anticipated to remain dominant through the period. A cold front will bring a wind shift to WNW at around 10-15 kts and gusty this evening. There is the potential for some lower clouds and patchy MVFR CIGs, but confidence is too low for mention. Will continue to monitor trends and update if needed. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...Cousins SHORT TERM...Cousins LONG TERM...Gibbs AVIATION...McClure
Area Forecast Discussion
National Weather Service Green Bay WI
835 PM CST Mon Feb 20 2023 New Information added to update section .UPDATE... Issued at 834 PM CST Mon Feb 20 2023 The latest RAP analysis and satellite/radar imagery show just north of Ironwood, MI and a cold front moving into central WI at 8 pm. A rather intense snowband in the warm advection zone of the cyclone has shifted into northwest Lower Michigan. A few calls to north-central WI revealed about 1-2 inches of snow has fallen so far today. Additional snow showers are moving east within the comma head of the compact shortwave trough located over far northwest WI. Combined with accums from lake effect snow showers late tonight, think another 1-2 inches of accumulations are possible over far north-central WI through 6 am Tue. A few mixed precipitation observations are occurring over central to north-central WI over the last 1-2 hours. It appears that ice crystals are being lost briefly within a narrow dry slot, but think amounts will be light enough that impacts will be minimal as the spotty mixed precip heads east. Lastly, gusts to 40 mph are moving into western Wisconsin and expect winds to become strong and gusty (30-40 mph) from late this evening into the overnight hours. Wind gusts will be the highest over central to east-central WI. && .SHORT TERM...Tonight and Tuesday Issued at 203 PM CST Mon Feb 20 2023 A strong Alberta Clipper brought a band of snowfall into central Wisconsin over the early afternoon hours. The initial round of snowfall moved through ahead of the main wind gusts, which kept visibilities a bit higher than previously forecast. As we continue through the evening, snow will continue to expand across the area. Most of central to east-central Wisconsin will see a lighter amount of snow with the fast moving band before snow tapers off. In addition, there is a small chance for rain during the afternoon before wet bulbing temperatures bring snow, further reducing the overall snow totals for most of the area. In the north however, between the left exit of the upper jet and the strong warm air advection, accumulations will be higher, with around 3-5 inches expected for Vilas County. As the clipper exits, snow will end for most of the region, the only exception being far northern WI where snow may continue at times as northerly flow continues across Lake Superior. Winds at the surface will increase in the evening as well, with gusts up to 30 to 40 mph, which could create some blowing and drifting snow. Tuesday will see a brief quiet period, with winds diminishing early in the day and no precipitation through the middle of the day. This will be short-lived however as the first round of a highly impactful winter system will begin moving into the region Tuesday evening. More details on this system will be in the extended period. .LONG TERM...Tuesday Night Through Monday Issued at 203 PM CST Mon Feb 20 2023 High-impact winter weather is expected this week, especially Tuesday night through Thursday. Headline decisions will be the main forecast concern. Tuesday night through Thursday... Models show significant isentropic lift and mid-level frontogenetic forcing Tuesday night, along with upper level divergence in association with the RRQ of a jet streak. A band of snow is expected to set up across mainly central and east central WI (south of Highway 29), with potential for 3-5 inches by daybreak Wednesday. Lesser amounts of 1 to 3 inches are possible north, but dry air near the Upper Michigan border could result in less. The forcing is expected to weaken Wednesday morning, before increasing again in our southern counties late Wednesday afternoon. Another inch or two of accumulation is possible in C/EC WI late in the day, and during the evening commute. Northeast winds will be ramping up through the day, with afternoon gusts reaching 25 to 35 mph north, and 35 to 45 mph south, especially in the Fox Valley and lakeshore areas. A surface low will track from the Central Plains to southern WI to southern Lake Huron during the Wednesday night to Thursday period. In addition, a negatively-tilted short-wave and associated deformation zone will move into the region on Thursday. The ECMWF Extreme Forecast Index (EFI) shows potential for a "highly unusual event" with respect to winds, QPF and snowfall. Model QPF is still suggesting a high-impact system, with the GEFS mean QPF for GRB around 1.2 inches for the duration of the event. Heavy snow (additional amounts of 10 to 14 inches), strong winds gusting to 35 to 45 mph (peaking Wednesday afternoon/evening), and considerable blowing/drifting snow look likely at this point. Snow and winds are expected to gradually taper off Thursday afternoon. Minor lake-effect snow showers will continue across north central WI into Thursday night. Headline Decisions... The plan is to treat this system as two distinct parts, with a Winter Weather Advisory across C/EC WI (along and south of Highway 29) Tuesday night into early Wednesday, then a Winter Storm Watch for the entire area starting late Wednesday afternoon (south) or early evening (north), and continuing through Thursday. Rest of the extended... A weak WAA/isentropic lift event will bring a chance of light snow Friday night, with a cold frontal passage continuing the potential for light precipitation into Saturday. Medium range models show the potential for a cyclone moving toward the western Great Lakes by next Monday, but confidence is low for a day 7 forecast. && .AVIATION...for 00Z TAF Issuance Issued at 523 PM CST Mon Feb 20 2023 - The first band of snow showers is lifting northeast across northeast WI late the afternoon and reducing visibilities to a half mile or less. This band will exit the Fox Valley by 00-01z. - The next band of snow showers is developing over northwest Wisconsin and expanding southeast. This band will slide across north-central WI through the evening hours though some short term models spread the snow into central WI. Will leave out of AUW/CWA for now and monitor. - Widespread MVFR and some IFR ceilings reside upstream over western WI and Minnesota. Think these lower ceilings will persist through much of Tuesday morning. - Strong and gusty west wind to northwest winds remain expected late this evening into early Tuesday morning. Gusts between 30 and 35 kts are likely. - The next round of snow will move into the central WI taf sites around 00z Wed. && .GRB WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 6 AM CST Tuesday for WIZ005. Winter Storm Watch from Wednesday evening through Thursday afternoon for WIZ005-010>013-018>022-073-074. Winter Weather Advisory from 6 PM Tuesday to 9 AM CST Wednesday for WIZ030-031-035>040-045-048>050. Winter Storm Watch from Wednesday afternoon through Thursday afternoon for WIZ030-031-035>040-045-048>050. && $$ UPDATE.........MPC SHORT TERM.....Uhlmann LONG TERM......Kieckbusch AVIATION.......MPC
National Weather Service Jackson KY
1106 PM EST Mon Feb 20 2023 .UPDATE... Issued at 1106 PM EST MON FEB 20 2023 WSR-88D still showing a ribbon of showers continues to push across parts of SE KY. There has been some signs of weaken over the past hour or so on the tail end of this line of showers and think this will be the trend the rest of the night. Given this updated PoPs accordingly and took thunder out of the grids based on the obs and trends. UPDATE Issued at 941 PM EST MON FEB 20 2023 WSR-88D is showing rain showers pushing east into parts of mainly SE KY this evening and these seem to be riding along a weak ribbon of lift at 300mb and perhaps a subtle wave at 500mb. This all coupled with a weak low and cold front nearby at the surface. We have a chance of seeing a few rumbles of thunder with some of these showers, but these should be isolated and mainly in the far SE. Either way will monitor to see if thunder will need expanded, with MRMS data showing some VII signal and some returns up to -20 degree C. However, MUCAPE of maybe 100 J/kg is all we are seeing from the SPC mesoanalysis which is quite meager, but the latest 00z HREF does show this same weak signal pushing across parts of eastern KY. Most areas north of the Mountain Parkway way will remain mostly dry outside perhaps Fleming County, but did opt to keep some slight PoPs given the nearby cold front. Given this mainly tried to time out the showers in this update and leaned toward the HRRR that has a better handle than most the other CAMs at this point. Otherwise, various grids were adjusted to the latest obs and trends. UPDATE Issued at 639 PM EST MON FEB 20 2023 WSR-88D and ASOS data is showing a few showers are pushing across eastern Kentucky this evening, as a wave of low pressure and cold front push east. We are seeing some lightning in the Cincinnati area and will monitor to see how this progresses east. Outside this forecast looks on track this evening and will update later as needed. && .SHORT TERM...(This evening through Tuesday night) Issued at 358 PM EST MON FEB 20 2023 Looking around the region at 1955z, temperatures range in the upper 40s on the far eastern ridges to mid 50s west of I-75 and north of I- 64. Regional radar shows this afternoon`s round of showers departing into West Virginia and Virginia. At 500mb, the Ohio Valley is sandwiched between an ~475 dam low spinning over the northern Hudson Bay while an ~590 dam high dominates the Caribbean. There are two notable embedded shortwaves, each supporting a surface low pressure. The first low pressure is found near/over the Gulf of the St. Lawrence and its cold front extends southwest across the Central Appalachians to along the Lower Ohio River where a poorly defined wave of low pressure is riding the boundary. Northwest of our region, the second low pressure system is located over Minnesota with its cold front trailing back across the Northern High Plains. A surge of moisture and WAA ahead of the poorly defined wave of low pressure riding the boundary draped just north of the CWA appears to be a driving factor for the showers now exiting to the east. The CAMs show additional disorganized showers developing along and ahead of the cold front this evening over Central and Eastern Kentucky and gradually exiting into Virginia after midnight. There does appear to be enough instability for a slight chance thunder mention, primarily over the Cumberland basin. Clouds should gradually thin from the northwest overnight. Considering the abundant surface moisture from today`s rainfall, suppressed high temperatures, and still saturated soil conditions, fog formation in the valleys seems probable in spite of little support from MOS guidance. Temperatures will remain mild only dropping to the upper 30s in northern hollows to the upper 40s over southeastern ridges. For Tuesday, drier air will continue to filter in on west northwest breeze, yielding plenty of sunshine for nearly all locations after any initial early fog/low stratus dissipates. The second low, passing from Minnesota to the Northeast US, will drop another dry cold front across the area during during the afternoon. Look for highs in the mid 50s north of I-64 to the lower 60s in the broader valleys near/south of the Hal Rogers/Highway 80 Corridor. On Tuesday night, a rapidly amplifying trough over the Western CONUS will initiate strong cyclogenesis over the Intermountain West and lee of the Colorado Rockies. This will cause a a southerly return flow to develop across the Ohio Valley. Temperatures will initially drop rapidly, especially in northeastern valleys where the low-level air will be quite dry. Increasing winds and cloud cover will keep temperatures notably warmer on ridges and further southwest. Expect a non-diurnal temperature trend with late evening lows in the middle 30s in northeastern valleys to around 50 in the warmest locales, followed by rising temperatures for the remainder of the night. A shower is possible late in the night as a warm front develops over the region but the better rain chances appear to remain north of the Jackson CWA. .LONG TERM...(Wednesday through Monday) Issued at 503 PM EST MON FEB 20 2023 Key points: *Temperatures will be reaching or breaking records potentially for Wednesday (22nd), and Thursday (23rd) *Rain chances through much of the extended *Models and WPC have trended down on the QPF for the weekend, but still a system to watch It`s still winter, but by Wednesday and Thursday of this week, it may feel more like late spring! At 12Z Wednesday, a surface low will be in place across the Central Plains, with a warm front stretched eastward across the Mid- Mississippi Valley and Kentucky/southern Ohio Valley. A strong llvl jet will set up just south of the warm front and extend southeast just ahead of the cold front. This will help to spawn showers and thunderstorms along both the warm front and associated cold front located over the southern Plains. The strong surge of southerly flow will continue through the day, pumping heat and moisture into the region. Temperatures are forecast to rise into the low to mid 70s by the afternoon, which could meet or exceed records for the 22nd. Also can`t rule out some potential for thunderstorms along the actual warm front, which should be across the far northern CWA in the morning, before lifting north of the area through the day. Pop potential from the NBM seemed reasonable with the timing that the models were giving for the pops increasing across the northern CWA and lifting north as well. The associated cold front will finally shift east through the state during the day Thursday, before weakening substantially by the time it gets to the eastern side of the state, as the parent low passes well to our north. With a llvl jet still across the state through the day Thursday, and winds from the SW, temperatures will surge again, this time well into the mid and upper 70s. The record for the 23rd in Jackson is 80 degrees, and London 77 degrees. If the exact forecast holds, London would be matching their record, and Jackson may come in just a couple degrees below. As the cold front moves through, all models show a scattering of precipitation along and just ahead of the front. This may likely be due to another surface low and upper level shortwave taking hold across the Mid-Mississippi Valley which will steal most of the energy, and weaken the system across the state. Also, a strong upper level ridge is in place across Florida and the Caribbean, and the ECMWF shows the ridging shifting north into the Tennessee and Ohio Valleys during the day Thursday (heights rising - but also helping to strengthen the trough to the west). With more westerly flow aloft instead of S or SW , we won`t be able to tap into as much Gulf moisture, so we lose a lot of moisture aloft as dry air moves into it`s place. Highest pops will be in the western CWA in the morning, scattering out as it moves east throughout the day. The secondary low that is developing to our west looks to pass north of the area, with a reinforcing cold front pushing through late Thursday into Thursday night. However, all the moisture should remain well north of the CWA where the jet streak is located, so the front looks to remain dry. A forecaster here stated, "You can`t have record breaking temperatures in the mid and upper 70s in February without paying for it." The very interesting thing about this system (and secondary system) for Wednesday and Thursday, is that we really don`t pay for it. The precip dissolves Thursday as mentioned above, and the secondary cold front will push much colder air into the region, but will remain dry. WPC and SPC have no mention of concerns for this time period. We don`t even have enough instability to include thunder along the cold front. By Friday, temperatures should top out some 30 degrees colder than Thursday - in the mid 40s to low 50s. Models do show some isolated pops trying to push north and into the southern part of the state, as a high pressure system passes north of the state. NW surface winds may also result in a little upslope component as well, but still sticking with isolated/slight chances at best as both the forcing and moisture are very minor. Attention then turns to the weekend, where improvements have been seen since the overnight forecast and model run. The strong high pressure system in control across the Ohio Valley will be shifting east of the region by Saturday, brining return SW flow into the state. Meanwhile, zonal flow will be in place in the mid and upper levels, so no strong push of moisture in the mid levels. However, at the surface, a low pressure will develop across the Rocky Mountain Piedmont, with a warm front spreading eastward along the zonal flow. With SW flow in place at the surface, this warm front will shift farther north throughout the day Saturday, stalling just south of the Commonwealth. Up until this point, models have been pegging this area, including Kentucky for high PWATS and persistent rainfall. However, today, the models have all lowered their QPF - and WPC followed suit. GFS does show an enhanced area of QPF Saturday afternoon, but most of it will be across eastern TN. Looking at GFS soundings, you can see a large pocket of dry air in the mid levels for a majority of the weekend. This is definitely a system to be watching, especially due to the stalled nature and parallel flow. However at this time, WPC is not talking about it in their outlooks, and 3-day storm total rainfall from Saturday through Monday has been reduced to under 2 inches for the southern CWA. Southerly flow at the surface tends to result in WAA, so look for warming temperatures through the weekend. Highs on Saturday will be in the low to mid 50s, and Sunday will be in the upper 50s to around 60. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) ISSUED AT 623 PM EST MON FEB 20 2023 We are seeing a mix of VFR to IFR Cigs this evening. This will be the story through the first 6 hours of the cycle, with a cold front slowly advancing east. This will lead to ups and downs in the Cigs as you see some improvement with Cigs in some of the passing showers, but this could also lead to a period of MVFR vis. All that said, the guidance does show sites seeing some improvement in the cigs through the night from northwest to southeast. Then the question becomes how much do we see fog wise and for now only have MVFR mist at LOZ and SME that seem to be showing the best signs of fog potential. The other sites see a bit more mixing noted with the forecast soundings in the wake of the cold front and less in the way of fog. All will improve to VFR by late morning on Tuesday, as we mix out any left over clouds or fog. Overall expecting winds to remain light and variable through the night, but should see increase in winds by late morning at 5 to 10 knots out of the WSW, with gusts of 15 to 20 knots possible in the afternoon. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...DJ SHORT TERM...GEERTSON LONG TERM...JMW AVIATION...DJ
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
522 PM CST Mon Feb 20 2023 ...Aviation Update... .SYNOPSIS... Issued at 335 PM CST Mon Feb 20 2023 H5 analysis from earlier this morning had high pressure anchored over the Gulf of Mexico. Closed low pressure was located just off the coast of northern portions of Baja California. Further north, a broad trough of low pressure extended across the northern two thirds of the CONUS. Within this flow, a strong shortwave was located over North Dakota. An associated surface low was located over west central Minnesota. Light snow was occurring from eastern North Dakota east into Minnesota, in association with this surface feature. Across western and north central Nebraska, skies remained partly to mostly cloudy this afternoon as a thick shroud of high level cloudiness continues to stream into the area from the west this afternoon. The cloud cover has limited temps somewhat this afternoon and 2 PM CT readings were in the 40s. Key Messages: - A winter storm appears likely Tuesday night into Thursday morning morning with the heaviest snow accumulations across the Sandhills into north central Nebraska. - Bitter cold wind chills are likely Thursday morning and may approach 40 below zero in some areas. - Another storm system may impact the area next Monday. && .SHORT TERM...(This evening through Tuesday night) Issued at 335 PM CST Mon Feb 20 2023 The next 18 hours will be fairly benign across the area. A weak back door cool front will push west into central Nebraska this evening, then lift to the northeast as a warm front overnight. ATTM, there is a slight signal for fog in the HRRR and NAM12 solns tonight. This is not supported by the statistical guidance. That being said, will forgo mention of this in this forecast package. Will pass my concerns onto the evening shift and have them watch this closely this evening. With passage of the front, winds will shift around to the south overnight. Lows will be in the lower to middle 20s. A strong arctic front will push through northern and central South Dakota on Tuesday, approaching the state line around 00z Wednesday. South of the front, warm H85 temps of 5 to 10C and westerly and southwesterly winds, will push highs into the mid 40s to lower 50s. Immediately ahead of the front, there will be a small threat for light rainfall over northwestern Nebraska late Tuesday afternoon and this was carried over from the previous forecast. The front will pass quickly through the area Tuesday night, exiting the forecast area by 12z Wednesday morning. Light snow will develop well behind the front late Tuesday evening and transition south to a line from Grant, to North Platte to O`Neill by 12z Wednesday. ATTM, the best lift is in a corridor from the east central Panhandle into the Sandhills and north central Nebraska overnight Tuesday night. By 12z Wednesday, snow accumulations should be 1 to 2 inches in these areas. .LONG TERM...(Wednesday through Monday) Issued at 335 PM CST Mon Feb 20 2023 Snowfall intensities will increase Wednesday morning across the Sandhills into northern Nebraska, thanks to increasing isentropic lift. Snow water equivalents will increase during the day given the cold air advection. Will approach a 20 to 1 ratio by Wednesday evening. Abundant lift in the dendritic zone will lead to efficient snow production Wednesday morning into the early afternoon hours. There will be a brief lull in snow intensity Wednesday afternoon. By Wednesday evening a secondary disturbance will lift into Kansas and eastern Nebraska. This will spread another round of snow to southwestern, central and north central Nebraska. The threat for snow will quickly end Thursday morning across the area, however, gusty winds will still lead to a blowing snow threat and bitterly cold wind chills Thursday morning of 30 to 40 below zero. Current headlines for winter weather end at 12z Thursday and this appears on track ATTM. However, we will probably need some sort of wind chill headlines for Thursday morning, through the noon hour. With respect to snow totals across the area. Ensemble mean precipitation totals have remained fairly consistent with the GEFS and ECMWF soln indicating event QPF`s on the order of 0.3 to 0.7 inches from the I-80 corridor, north to the SD/NE border. As for snow accumulations, utilized a 15-1 to 20-1 SLR for the event given the forecast temperatures during the event. This yielded snow totals from 4 to 12 inches from a line from Grant-North Platte-Bartlett to the SD/NE border. I went ahead and manually did some upward adjustment to the WPC QPF forecast over southwestern Nebraska to bring this more in line with the GEFS and ECM ensemble mean QPF. This gave me a QPF for North Platte of 0.28 inches which equated to a 4.3 inch snow total for the event. With respect to headlines for the event. Went ahead and upgraded the watch to a warning for all counties in the watch, and added Keith and Deuel counties to the warning. Was on the fence with Deuel and Keith, however, felt with the interstate and the threat for blowing snow a warning vs. an advisory was warranted here. Went ahead and issued a watch for Perkins, Lincoln, Custer, Garfield and Wheeler counties. The bulk of snow for these areas should arrive with the second disturbance Wednesday night. Given the lighter accumulations and later timing, felt we had some more time to re-assess the situation tonight. After very cold temperatures Thursday and Friday, readings will moderate back into the 40s for Saturday, Sunday and Monday. Early next week, a strong upper level system will cross the central and southern plains. This storm will bear watching as it has a good gulf tap of moisture and could be a decent wind and precipitation producer. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 521 PM CST Mon Feb 20 2023 A weak cold front will back into wrn and ncntl Nebraska tonight. The front could be the focus for MVFR/IFR ceilings and vsbys Tuesday morning across either ncntl Nebraska or swrn Nebraska. The location of this flight concern will depend on how far south or west the front moves tonight. The model consensus suggests ncntl Nebraska will be the focus for low ceilings and vsby. Either way, the front will lift north and east of the region late Tuesday morning and VFR is expected across wrn and ncntl Nebraska 18z-00z Tuesday afternoon. && .LBF WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning from 6 PM CST /5 PM MST/ Tuesday to 6 AM CST /5 AM MST/ Thursday for NEZ004>010-022>027-035>037-056-057- 094. Winter Storm Watch from late Tuesday night through late Wednesday night for NEZ028-029-038-058-059. && $$ SYNOPSIS...Buttler SHORT TERM...Buttler LONG TERM...Buttler AVIATION...CDC
Area Forecast Discussion
National Weather Service Louisville KY
918 PM EST Mon Feb 20 2023 .Forecast Update... Issued at 915 PM EST Mon Feb 20 2023 Diffuse cold front is within the vicinity of the Ohio River this evening, and will slowly shift southeastward through the night, though will not clear our region until tomorrow. Line of light isolated showers are observed from Warren to Lincoln counties, with an eastward trajectory due to western 30 kt winds at 5k ft from the VAD Wind Profiles. We`ll see these showers diminish tonight, and should be a dry forecast for the overnight. The prior convective- shower line near the I-71 corridor has diminished as expected due to nocturnal cooling. Min temps for tonight will range from low 40s north of the Kentucky Parkways, to mid to upper 40s to the south. Current forecast remains in good shape, so will not send a second round of updated products at this time. Issued at 715 PM EST Mon Feb 20 2023 Seeing a line of convective-looking showers along the I-71 corridor, stretching from NE Jefferson County KY to the CVG area. These showers and few rumbles of thunder are developing in response to deep moisture convergence along the cold front, in a thin corridor of 100 J/kg of MUCAPE and steep low level lapse rates pushing 7 C/km. Though we could see a brief heavy downpour in our northeast CWA, these cells are topping out around 15k ft. With only 30 kts of effective bulk shear, these cell should remain disorganized and below severe thresholds. HRRR and NAM Nest have a good handle on current conditions, and expect to see these showers push southeast through the Bluegrass this evening as they weaken. Current forecast is in decent shape with PoP location, though will blend in latest hi- res guidance to match up a bit better with current trends. Updated products will be sent shortly. && .Short Term...(This evening through Tuesday) Issued at 310 PM EST Mon Feb 20 2023 A weak cold front across southern Indiana is slowly working towards the southeast. About the only thing this front is doing is separating clearer skies to the north from low level moisture to the south, mainly across central and eastern Kentucky. This low moisture is causing fairly dense cloud cover between 1,000 to 3,000 feet along and south of Interstate 64. Through the evening and early part of the night, the cloud cover will get pushed to the east, but before exiting the region, recent CAM model guidance is increasing the likelihood of rain chances along and east of Interstate 65. This would be driven by isentropic lift. The best chances for measurable rainfall will be over the Lake Cumberland region. Precipitation totals are expected to stay around and below a tenth of an inch. Lows will drop into the 40s. Tomorrow morning, the aforementioned cold front is expected to be most of the way through central Kentucky as a second cold front begins dropping south across southern Indiana towards Kentucky. This second front will cause winds to shift from the southwest to the northwest as surface high pressure moves into the region behind the front. Skies should clear, but CAA will help limit high temperatures to the 50s. .Long Term...(Tuesday night through Monday) Issued at 335 PM EST Mon Feb 20 2023 Key Messages: - Active weather is expected by midweek with a conditional risk of strong to marginally severe storms. - Unseasonably warm with near record temperatures Wed & Thu - Gusty gradient winds of 30 to 40mph possible on Thursday - Possible river flooding by the weekend Synopsis...Mid-level pattern amplification will be ongoing at the start of this forecast period. Longwave trough will deepen over the western half of the country as a 250-mb jet max rounds its base. The leading edge of the digging large-scale trough will eject a Baja low towards the Mid Mississippi Valley on Wednesday given the strong blocking high extending across the Southeast US. Gradual northward extension of the upper ridge will lift a diffuse frontal zonal through the lower Ohio Valley Tuesday night into Wednesday morning as a warm front. On the other hand, the northeastward progress of the Baja low will be characterized by transformation into an open wave with some dampening of the mid-level vorticity signal as it speeds ahead of the larger trough. At this point, lee cyclogenesis will take place in the Front Range with a general motion towards the Midwest/Great Lakes on Thursday which takes a cold front across the region. For the weekend, the mid-level flow splits once again with upper low spinning over California and upper ridge pushed westward to the central US by a intense shortwave trough moving from Canada to the Great Lakes and Northeast US. Model Evaluation...Model consensus remains above average regarding the synoptic evolution until Friday. The weekend forecast is still more uncertain and therefore low confidence is placed during that period. The most notable changes during the last 24 hours worth of runs are the GFS nudging towards the ECMWF to have a more amplified downstream trough, although timing differences still exist, and the CMC tendency to actually depict a less amplified trough which is more in tune to what the GFS was showing few runs ago. As for the mesoscale elements, the heaviest rainfall accumulations associated with the lifting warm front are still anticipated to occur north of the CWA with the exception of the GFS that keeps exhibiting light QPF along northern Kentucky and southern Indiana. Another source of uncertainty arises with Thursday temperatures due to high model spread probably related to timing variability of the cold frontal passage that day. Last but not least, there is growing signal for a wintry precipitation Saturday morning in the Bluegrass area as a baroclinic zone lifts over near-freezing surface temperatures. The official forecast maintains precipitation as rain during that period because confidence is still low to introduce any kind of frozen hydrometeors. Tuesday Night - Wed Morning...As stated in previous discussions, expect increasing showers through the night into the morning hours especially north of I-64. The nocturnal activity will be elevated in nature with steep lapse rates above 850-mb, strong shear, and some incipient SRH in the effective inflow layer. So, organized convection with sustained and robust updrafts are plausible as the warm front lifts north with a chance of thunder and moderate rainfall. Taking into account the QPF trend, flash flooding is not considered, but upstream runoff might play a role in river gauges along the Ohio river going into the weekend. Wed Afternoon - Wed Night...As the shortwave approaches the Mid Mississippi Valley and the rain focuses in central/northern Indiana, a WAA regime will be ongoing in the lower Ohio Valley with the possibility of some clearing in between clouds. As a result, temperatures will climb fast throughout the day with guidance exhibiting records highs in the afternoon. Then, the next wave of precipitation will approach the region by the evening. The warm sector environmental conditions will be characterized by high shear and low instability with some models indicating few hundreds J/kg of MUCAPE if the convective activity reaches the area around sunset. The 500-mb height falls are very much aligned with the surface trough, so don`t expect much of pre-frontal showers before the main precipitation shield. The CSU ML algorithm has been showing decent probabilities of severe weather for the period which can be supported by the presence of potential instability, mesoscale lifting, strong shear, and dynamical forcing along the intense LLJ. However, the lack of instability in an unfavorable diurnal time might be enough to cap the convective initiation and maintenance. Thursday - Friday...Cooler and drier weather is expected as the main surface low moves to the Midwest and cold front slowly sweeps the area. Temperatures will still be on the warm side on Thursday, but as stated above this is a low confidence scenario. Winds will race ahead and along the southward-sagging front with gust between 30 to 40 mph. Cooler temps are reflected on Friday with lighter winds overall. Weekend...The aforementioned cold front might be on its way northward during the weekend with broad isentropic lifting over the Ohio Valley. Several waves of precipitation might cause fluctuations in rivers, so QPF tendencies will have to be monitored. && .Aviation...(00Z TAF Issuance) Issued at 620 PM EST Mon Feb 20 2023 Satellite imagery continues to show clearing skies north of a weak cold frontal boundary, with a few light showers developing across the area. Other than some vicinity showers possible at BWG and LEX within the next hour or two, we should see ceilings improve tonight. Expect VFR conditions across all terminals for the overnight period. For tomorrow, a secondary cold front passes through late in the period, which will bring a rapid wind shift with it (just beyond this period for all terminals except SDF). Expect winds tonight and tomorrow morning to mainly be from the west-southwest, and northwest by tomorrow afternoon. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...CJP Short Term...KDW Long Term...ALL Aviation...CJP
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
939 PM EST Mon Feb 20 2023 .SYNOPSIS... A wave of low pressure passes to the northwest tonight before a cold front tracks through on Tuesday afternoon. Temperatures return to near normal by mid-week before near record warmth on Thursday. A stronger cold front arrives by late Thursday leading to a brief cooling trend into the weekend. && .NEAR TERM /THROUGH TUESDAY/... Mid-evening update: Current radar imagery shows rainfall blossoming across WV and PA. This area of showers will work eastward across the forecast area during the overnight hours, with locations along/north of I-66/US-50 having the highest coverage of showers. Previous discussion follows... Light rain shower chances continue into the night along the Alleghenies. Totals amounts should top out in the 0.10-0.20 inch range with perhaps a trace to 0.05 inches to the east. The main inhibiting factors for locations to the east are the expansive dry sub-cloud layer and less than optimal forcing. Plenty of clouds linger into the night leading to very mild conditions for mid/late February. Forecast lows range from the mid/upper 30s along the Alleghenies to low/mid 40s elsewhere. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... Mid-evening update: Strongly considered issuing a Wind Advisory for much, if not all of the forecast area tomorrow, but decided to hold off and let the midnight shift evaluate 00z guidance. The strongest winds will be immediately along/just behind a cold front working across the area tomorrow afternoon into tomorrow evening. Most model guidance shows 40-45 knots atop the mixed layer for a 2-4 hour window along/just behind the front through the afternoon and into the evening. 00z CAMs also show surface based instability (on the order of 100-500 J/kg) developing ahead of the front as temperatures cool within the 850-700 hPa layer. Some CAMs (notably the 00z HRRR) try to develop thunderstorms in the vicinity of the front as it passes to the east of the Blue Ridge toward I-95. This will be something to keep an eye on, as there will be plenty of wind aloft to bring down if thunderstorms do develop (65-75 kts at 700 hPa). The 00z HRRR even shows some weak updraft helicity tracks, indicating rotating updrafts, which seems plausible given the impressive shear through the cloud bearing layer coupled with the weak instability. Previous discussion follows... The mentioned frontal zone generally settles off to the north of the area while a more potent boundary looms farther upstream. Given the close proximity of the former system to the region, some rain shower chances persist during the first half of Tuesday. Most notably, this includes much of the Allegheny Front eastward along the Mason-Dixon Line into northeastern Maryland. As the stronger cold front tracks through Tuesday afternoon, some of the 12Z HREF members show some 40 dbZ caliber reflectivity cores north of the DC metro into northeastern Maryland. Thus, some brief heavy showers are certainly not out of the realm of possibilities between noon-3 PM. With the cold front sweeping through the region Tuesday afternoon, a healthy wind field accompanies this system with a deepening mixed layer in the wake. Depending on the model solution, some 35 to 40 mph winds will likely mix down in the gusty post-frontal environment. This could easily approach the 40 to 50 mph range across the Blue Ridge and Alleghenies. Gusty downsloping winds should mix dry adiabatically to the surface yielding a very mild day. Have continued to favor high temperatures well into the 60s across the lower elevations. Some areas along I-95 in central Virginia could reach 70 degrees. The air mass is also be quite dry as dew points fall into the upper teens to 20s. The stronger winds begin to abate into the night with cooler temperatures on tap. Expect Tuesday night`s lows to be in the 30s. Mid/upper heights begin to rise in earnest on Wednesday. The resultant warm advection flow will override a still cold air mass at the surface. The isentropically induced precipitation could yield some light freezing rain from the northwestern Alleghenies eastward along areas of the Mason-Dixon Line. The biggest question is whether enough of this region will still be at freezing when the precipitation arrives. At this point, have kept the best chances for light ice accretions across western portions of Grant and Mineral counties as well as western Maryland and the Catoctins. Eventually this shifts over to rain for all by the afternoon with amounts generally up to 0.10 inches. Forecast highs are around climatology, but readings do not fall much into the night as lows remain in the 40s to low 50s. && .LONG TERM /THURSDAY THROUGH MONDAY/... With the warm front north of the region by Thursday morning, Thursday will likely be the warmest day of 2023 thus far. Unseasonably warm air will usher into the region with widespread high temperatures in the 70s to near 80F. The mountains will stay in the 60s, which is still anomalously warm. Record breaking high temperatures are certainly plausible for Thursday. A weak cold front will pass through Thursday night bringing the potential for rain showers. The bigger threat along and behind this front will be the potential for gusty winds. Latest probabilities suggest 30-40 mph winds areawide, with gusts up to 50 mph across the higher terrain west of the Blue Ridge Thursday afternoon into Thursday night as the pressure gradient tightens. With the CAA, Friday will be dry and more seasonable with temps in the 40s for most (30s in mtns, 50s in central VA into southern MD). Winds will gradually decrease through the day. Friday night will be the coldest of the week as high pressure meanders nearby. Precipitation chances increase Saturday with the next system. Most places likely stay rain, though another wintry mix is possible along the Mason-Dixon line. Will continue to monitor. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... VFR conditions are likely through Tuesday night across all terminals. There will be a slight chance for showers to impact the TAF sites overnight. However, given the low confidence, have opted to go with a vicinity shower group at all locations between 01-08Z. Do not anticipate any restrictions though. A few showers may impact the more northern terminals through early Tuesday afternoon. Eventually a strong cold front sweeps through during the afternoon leading to westerly gusts up to 30 to 35 knots. Such gusts linger into the early/mid evening before dropping over into Tuesday night. Light warm advection precipitation impacts the area on Wednesday. Any potential for freezing rain likely stays well west of KMRB. Models do lower ceilings to MVFR on Wednesday, with perhaps a further drop to IFR by Wednesday night. Wind fields generally stay out of the east to southeasterly direction. VFR conditions return on Thursday and persist into Friday. Gusty winds out of the southwest will develop out of the southwest and increase through the day on Thursday into Thursday night before decreasing on Friday. && .MARINE... West to southwesterly winds continue to remain under advisory. Some portions of the lower Chesapeake Bay have begun to approach 18 knots, but these should quickly fall off in the next few hours. As a seasonably strong cold front tracks through on Tuesday afternoon, Small Craft Advisories go into effect across all waters by noon. There will also be a period of gale-force wind potential between 1-7 PM, particularly over the upper tidal Potomac and northern half of the Chesapeake Bay. Advisory caliber winds continue into the mid/late evening before falling off into the night. Sub-small craft winds continue through mid- week. SCA winds are likely Thursday and most of Friday before winds begin to decrease over the waters. Gale force wind gusts are possible over the waters during this time, especially north of the Chesapeake Bay Bridge. && .FIRE WEATHER... A strong cold front moves through the region Tuesday afternoon which will usher in dry and very gusty westerly winds into the early/mid evening hours. Forecast gusts will be around 30 to 40 mph, locally up to 45 to 50 mph across the mountains. A dry downsloping wind will yield minimum relative humidity values down into the upper teens to mid 20s. The main inhibiting factor will be the marginally dry 10-hour fuels for areas south of I-66. Additionally, some light rainfall arrives later this evening and into the overnight. Although these will likely fall short of being a wetting rain, it is unknown how much these showers will impact the the dead fuel moistures. && .CLIMATE... Potential for daily record high temperatures on Thu (2/23): (*) Sites where the NWS maintains temperature records RECORD HIGH TEMPERATURES THU (2/23): Washington/Reagan National 78 (1874): records since 1872* Washington Dulles Airport 77 (2017): records since 1960* Baltimore/Washington Arpt 78 (1874): records since 1872* Martinsburg Airport 77 (2017): records since 1891* Charlottesville Airport 78 (2022): records since 1893 Hagerstown Regional Arpt 76 (2017): records since 1899 Annapolis Naval Academy 74 (2022): records since 1894 && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory from noon to 6 PM EST Tuesday for ANZ530>543. && $$ SYNOPSIS...BRO NEAR TERM...BRO/KJP SHORT TERM...BRO/KJP LONG TERM...CPB AVIATION...BRO/CPB MARINE...BRO/CPB FIRE WEATHER...BRO CLIMATE...LWX
Area Forecast Discussion
National Weather Service Melbourne FL
836 PM EST Mon Feb 20 2023 ...New UPDATE, MARINE, AVIATION... .UPDATE... Issued at 815 PM EST Mon Feb 20 2023 Remainder of tonight...Surface ridge axis will remain anchored across far SOFL and the Keys. Light WSW to west flow will keep warm conditions in place, with skies mainly clear, aside from some thin cirrus clipping the northern CWA. Given the slightly stronger westerlies just above the surface, there is potential for low clouds to develop over/inland from the GOMEX and push east across the peninsula overnight. Low confidence on this occurring, although the latest iteration of the HRRR suggests low clouds and fog pushing from SWFL inland to Lake Okeechobee very late, so will need to watch for this on RGBNTM imagery. With dry air in place, mins will drop to within a degree or two of 60F by sunrise across most areas. No significant changes to the inherited forecast. && .MARINE... Issued at 835 PM EST Mon Feb 20 2023 Weak trough along the FL east coast is keeping winds on the lighter side this evening, however model guidance is unanimous in dampening this feature out as stronger westerlies sag south across the waters, especially north. Since winds will be W-WSW any increase in seas should be limited and confined to the waters well offshore. Nevertheless speeds should eventually wind up close enough to 20kt to continue the SCEC (late) for the Volusia/Brevard 20nm legs. && .AVIATION... (00Z TAFS) Issued at 835 PM EST Mon Feb 20 2023 VFR. Kept the mention of ST/low based SCU @SCT015-020 working its for the north of the VRB-SUA corridor late tonight. As mentioned above, at least some potential exists for MVFR to possibly high end IFR CIGs, mainly the interior aerodromes. && .PREVIOUS DISCUSSION... Issued at 228 PM EST Mon Feb 20 2023 Tuesday...A pronounced sfc ridge across the Nrn Bahamas to the central Gulf wl become more vertically developed as an upr ridge across Cuba slowly extends farther north. A westerly flow regime over the state wl experience some increase in LL moisture. Even warmer than today...plenty of sun with aftn highs in the M80s for the coast/inland areas east of I-4, generally L80s west of I-4. Wednesday-Sunday...The remainder of the week will be characterized by a lack of rain chances and unseasonable warmth, knocking on the door of record high temperatures; not only daily records but potentially monthly & seasonal records as well. Ridging aloft will float from the Gulf of Mexico towards Cuba and then center over the Bahamas through the period, pushed eastward by a trough digging from TX towards the Great Lakes. Any evidence of a surface low and cold front is washed out by Wednesday due to a dominant and strong Atlantic high with an axis stretched across central Florida. Later in the week, the center of this high is poised to shift closer to the peninsula. Moisture from the ghost cold front will pause just north of FL on Thu/Fri, leaving PW values below 0.90" into the weekend. Dry conditions continue heading into the weekend, with 0 PoPs for the next 7 days. The focus shifts to the high temperature forecast, as values will climb to the upper 80s to near 90 degrees across the interior; a few degrees lower at the immediate coast with assistance from the afternoon sea breeze. The entire ensemble of record highs (daily, monthly and seasonal) will be at risk for interior sites Wed- Sun, and possibly be the first time on record that Leesburg and Sanford hit 90 degrees in February and the first in 6 decades for Orlando. Luckily, lower dewpoints will keep humidity low and out of the oppressive category, despite the well above normal highs. Lows will also range above normal in the low 60s but still be several degrees shy of warm minimum records. && .MARINE... Issued at 228 PM EST Mon Feb 20 2023 Tuesday...Offshore/westerly flow 15 to 20kt over the open waters early, esp well offshore and a caution stmt will remain in effect beyond 20 NM with seas remaining below 6 ft due to limited fetch. Winds are expected to diminish below SCEC criteria by afternoon. Wednesday-Friday...Surface high pressure will remain the dominant feature through the end of the week, leading to generally benign boating conditions with the exception of late Wed/early Thu. A dissipating cold front will press towards the local area, washing out before it reaches FL, however the pressure gradient will tighten slightly with the proximity of the high. Thus, a brief southerly wind surge will increase winds over the offshore waters to 15-20 knots but drop below 15 knots by daybreak Thu. Winds will veer westerly towards the end of the week, with no rain in the forecast. Seas generally 2-4 ft. && .PRELIMINARY POINT TEMPS/POPS... DAB 80 59 82 59 / 0 0 0 0 MCO 83 62 84 60 / 0 0 0 0 MLB 83 59 85 60 / 0 0 0 0 VRB 85 59 86 59 / 0 0 0 0 LEE 81 61 81 61 / 0 0 0 0 SFB 83 60 83 59 / 0 0 0 0 ORL 83 62 84 61 / 0 0 0 0 FPR 85 61 85 61 / 0 0 0 0 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ SHORT TERM...Cristaldi LONG TERM....Schaper AVIATION...Cristaldi
Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
859 PM CST Mon Feb 20 2023 .UPDATE... Issued at 859 PM CST Mon Feb 20 2023 After pouring over more data, made some headline changes for midweek with more likely to come in future shifts. The remaining Winter Storm Watch is being upgraded to a warning along and south of I-94 (except the counties along I-94) beginning Tuesday afternoon. It is here the heaviest snow will fall Tuesday afternoon and night. While the biggest uncertainty for this massive winter system will be on Tuesday with the placement of this band and resultant snow totals, hi-res guidance is favoring a more northerly placement compared to the GFS and Canadian which appear southern outliers. Amounts have increased slightly farther north and a wide swath of 4 to 7 inches is now expected, including the I-94 corridor. Some guidance is heavier, which is typically the case with frontogenetically driven snow bands, but confidence is too low with where these heaviest and most persistent bands will develop to explicitly show heavier totals in the forecast at this time. It wouldn`t be surprising to see some 8 or 9 inch totals with just round one. Farther north from Douglas Co, MN to Rusk Co, WI, a Winter Weather Advisory is in effect for 3 or 4 inches. After a break Wednesday morning, the next round will surge north later in the day and become quite heavy Wednesday night and early Thursday. Not much has changed with this round. A Winter Storm Warning is in effect for the entire area during this time. An additional 10 to 20 inches are likely. Strong winds and such heavy snow totals will make for drifts that could be several feet deep. This and the low visibility due to heavy snow and blowing snow will make travel impossible or nearly impossible across the region. Given the degree of blowing snow this evening following just one or two inches of snow earlier today, there are serious concerns for how bad conditions will get Wednesday night. Given the lack of friction with the smooth, crusted-over snow pack, conditions are prime for considerable blowing snow. It may not take the typical wind gusts of 45 to 50 mph to solidly reach blizzard conditions on a widespread basis. Still plenty of time to watch wind gusts and further upgrades, so maintained the Winter Storm Warning. && .DISCUSSION...(This evening through Monday) Issued at 255 PM CST Mon Feb 20 2023 KEY MESSAGES: - TUESDAY THROUGH THURSDAY: A significant winter storm consisting of two rounds of heavy snow and gusty winds will impact our entire county warning area. First will be 4 to 7 inches of accumulating snow Tuesday afternoon into Wednesday morning. A "lull" with light snow will follow Wednesday mid-morning to Wednesday afternoon. - A second, more widespread round of accumulating snow will begin Wednesday late afternoon through Thursday afternoon. An additional 8 to 12 inches is likely for much of the area. Additionally, Winds will increase with widespread blowing and drifting snow across western and south-central Minnesota. Blizzard conditions with near- zero visibility will be possible Wednesday night into Thursday morning. Travel impacts are certain Tuesday evening through Friday. Expect considerable disruptions to daily life. IMPORTANT CHANGES: Upgrade to a Winter Storm Warning for portions of west-central MN set to begin at 12PM Tuesday and the portions of the Twin Cities metro at 3PM Tuesday. A Winter Storm Watch remains in effect for portions of southern and central Minnesota due to less confidence in snow amounts for round 1 Tuesday PM/Wednesday AM. These counties will require an upgrade at a later time due to the additional accumulating snow Wednesday PM into Thursday with round 2. Today... The Twin Cities morning commute was greeted with a band of heavy snow that pushed through along an impressive low level warm front. Heavy snow rates of 2 inch an hour resulted in 1/4 mile visibility or less and a quick inch or two of snow before weakening and moving into WI. Currently, areas of light snow will continue along and north of I-94. Most locations should end up with an inch or two by the end of the day. Current obs show most have warmed up into the mid 30s with southerly winds between 15 to 20 mph behind the warm front. Several sites are gusting up to 35 mph and will lessen after sunset. Winds turn westerly this evening and northwesterly tonight. Tonight through early Tuesday will be dry and chilly, with lows in the single digits and below. INFORMATION ON THE LONG DURATION WINTER STORM BELOW TUESDAY THROUGH THURSDAY... Overall, the changes to the forecast have been relatively minor, tightening the initial snow gradient Tuesday night and a slight shift in the highest snow/ice totals. Guidance generally is in good agreement and confidence has remained high on the overall scenario. There remains some uncertainties in the finer mesoscale details that will need to be worked out such as where banding sets up. However, this event will be a rather significant with high-end impacts for a very large portion of our forecast area in MN and western WI. ROUND 1: Tuesday afternoon to Wednesday morning... Tuesday kicks us off with an FGEN driven swath of snow that will move across southern MN into central WI. Low level FGEN snow bands can lead to a narrow band of locally higher snowfall totals that are difficult to pick up on global weather models. Hi-res short range models are getting into range and are able to better resolve such features. This will lead to tightening on with the forecast snow totals over the next 12 to 18 hours. Current guidance highlights the heaviest snow between the northern boundary, Twin Cities metro, and the southern boundary, I- 90 corridor in S MN. The band looks to set up from Redwood Falls, MN into Twin Cities metro to Eau Claire, WI. Snowfall amounts of 4 to 6 inches will be possible, with locally higher amounts possible due to banded snow structure. Hi-res models such as the HRRR have been further north with the initial band while the global models remain further south. There are also a few higher QPF forecasts from hi- res/CAMS that put out 0.40" to 0.60"+ across. This would support higher amounts than are currently forecast. As this is primarily driven by FGEN, hi-res guidance may have the upper hand in resolving those features. LULL: By Wednesday morning, a lull will arrive for a period of six to eight hours. It is important to note that it will be a lull and NOT a break (with the exception of areas north of St.Cloud, they might actually get a break). Light snow will continue through Wednesday morning, only accumulating an inch or so over a six hour period. By the end of the lull Wednesday afternoon, winds will begin to increase as the main system begins to eject out of the Rockies into the Central Plains. As the winds increase, expect the potential for blowing snow to increase across western and southern MN. ROUND 2: By Wednesday Afternoon, the upper level synoptics take over as a broad precipitation shield develops across the area. Bands of heavy snow will exist in the shield, but compared to Tuesday night`s snow, will be much more widespread. As the synoptic setup gets going, we`ll turn to the potential for heavy snowfall Wednesday evening into Thursday morning AND gusty winds due to a strong pressure gradient with an Arctic High to the north over Canada. Phasing between the Polar and Sub-Tropical jet will ramp up Wednesday night. This will result in an impressive uptick in upper level winds, 150 to 200+ MPH, and provide plenty of support for the developing low pressure system. The resulting sustained surface winds of 30 to 35 MPH will shift from E to NE to NW by Friday. The associated gusts could reach upwards of 40 to 50 MPH, especially in southern and western MN. When you put several inches of freshly fallen snow (with several more inches ongoing) and these strong winds together will result in widespread blowing and drifting snow, especially across our blizzard prone areas of western and southern Minnesota. Significant travel impacts due to low visibility and drifting/blowing snow are likely Wednesday night into Friday. If this forecast holds, Blizzard Warnings are likely for the second half of the storm. As for when and exactly where the threat transitions from snow load/poor roads to poor visibility and inability to travel, that decision will be made in the following forecast packages. Moderate to heavy snow will be likely across the area Wednesday night into Thursday. Snowfall rates of 1 to 2 inch per hour could be possible under these heavier bands. Snow ratios of 15:1 to 18:1 are likely. QPF forecast highlights a band of 0.75" to 1.00" with the second round along the same corridor as Tuesday night`s snow (Between the southern Metro and I-90). The lighter, fluffier snow will be easy for the 40 to 50MPH gusts to pick up and blow around leading to significantly reduced visibility and potential white-out conditions with near-zero visibility. Snowfall will lighten and gradually taper of Thursday afternoon. It`s important to note that these systems tend to linger longer than what guidance usually depicts, so light snow lasting into Thursday evening or even Thursday night isn`t out of the question. By Friday morning, most of the forecast area will pick up another 12 inches or more. When you add it all up, most of the forecast area will end up with 12 to 18 inches. Locally higher amounts, 20 to 24 inches, aren`t out of the question for areas that double dip with round 1 and 2. It`ll be difficult to measure Friday morning, but the damage will be done when you consider the widespread disruptions to daily life and travel through this period. These conditions will be slow to improve as winds slowly decrease and plummeting temperatures into the -5 to -15F range limiting the effectiveness of road salt and continued blowing/drifting snow Thursday night into Friday. I`ll save the hockey references this time around, but I`ll reiterate a few takeaways: 1: Two rounds of accumulating snow, First is Tuesday afternoon into early Wednesday morning, and second is Wednesday afternoon through Thursday afternoon. 2: First round of 4 to 7 inches, locally higher, between Twin Cities and I-90 corridor, along a line from Redwood Falls to Eau Claire, WI. 2 to 4 inches of snow across central MN. 3: Second round will be more widespread with an additional 8 to 12 inches, locally higher, across the entire forecast area. Winds will increase to 20 to 30 MPH, gusting 40 to 50 MPH, and lead to widespread blowing and drifting snow Wednesday evening through Thursday night. Blizzard conditions with near zero visibility are possible, especially across western and southern Minnesota. 4: 12 to 18" totals when the event is over, with localized 20 to 24" amounts for those "double dip" both rounds of snow. Gusty winds will lead to significant widespread blowing and drifting snow. Friday through Sunday... Cold will filter in on the back end of the system. Friday morning lows will vary between -5 to -15F. Winds will be light enough that Wind Chill headlines are not expected at this time. The cold won`t last long as warm air advection will bounce our highs back into the 20s on Saturday and Sunday. It`ll remain dry, but temperatures below freezing, as we dig out. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 555 PM CST Mon Feb 20 2023 Northwest winds have increased and are gusting 30-40 kts across central and western MN. This has led to areas of blowing snow. Otherwise, MVFR cigs likely to continue for much of the night before scattering out early Tuesday. The first round of snow this week will advance east across the area in the afternoon with conditions deteriorating quickly after the onset. KMSP...MVFR cigs tonight. There could be some brief reductions in vis with patchy blowing snow, but not confident enough it will be impactful enough to include it in the TAFs. Snow will begin to arrive around 21Z Tuesday, with IFR/LIFR conditions expected thereafter. /OUTLOOK FOR KMSP/ Wed...IFR/-SN early, then LIFR/VLIFR/+SN late afternoon and night with BLSN. Wind NE 15-20G30kts increasing to 20-25G35-40kts. Thu...LIFR/VLIFR/+SN early, then MVFR/IFR/-SN likely. BLSN. Wind NE 20-25G35kts becoming NNW 15-20G30kts. Fri...Chc MVFR. Wind WNW 5 kts becoming S. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...Winter Weather Advisory from noon Tuesday to 6 PM CST Wednesday for Benton-Douglas-Morrison-Todd. Winter Storm Warning from 6 PM Wednesday to 6 PM CST Thursday for Benton-Chisago-Douglas-Isanti-Kanabec-Mille Lacs-Morrison-Todd. Winter Weather Advisory from 3 PM Tuesday to 6 PM CST Wednesday for Chisago-Isanti-Kanabec-Mille Lacs. Winter Storm Warning from noon Tuesday to noon CST Thursday for Brown-Chippewa-Kandiyohi-Lac Qui Parle-Meeker-Pope-Redwood- Renville-Stearns-Stevens-Swift-Watonwan-Yellow Medicine. Winter Storm Warning from 3 PM Tuesday to 6 PM CST Thursday for Anoka-Blue Earth-Carver-Dakota-Goodhue-Hennepin-Le Sueur- McLeod-Nicollet-Ramsey-Rice-Scott-Sherburne-Sibley-Steele- Waseca-Washington-Wright. Winter Storm Warning from 6 AM Wednesday to noon CST Thursday for Faribault-Freeborn-Martin. WI...Winter Storm Warning from 6 PM Wednesday to 6 PM CST Thursday for Barron-Polk-Rusk. Winter Weather Advisory from 3 PM Tuesday to 6 PM CST Wednesday for Barron-Polk-Rusk. Winter Storm Warning from 3 PM Tuesday to 6 PM CST Thursday for Chippewa-Dunn-Eau Claire-Pepin-Pierce-St. Croix. && $$ UPDATE...Borghoff DISCUSSION...BPH AVIATION...Borghoff
Area Forecast Discussion
National Weather Service Norman OK
504 PM CST Mon Feb 20 2023 ...New AVIATION... .SHORT TERM... (This evening through Tuesday) Issued at 238 PM CST Mon Feb 20 2023 Weak surface low pressure over the Texas Panhandle is expected to move southeast and east across far southern Oklahoma this evening. This should bring a north to northeast wind (although light) to most of the forecast area. The overall trend with this feature has been farther south over the past several days. This should allow slightly drier air to advect southward and bring cooler overnight lows, especially compared to last night( the exception is northern Oklahoma where lows were rather chilly). Surface winds are still expected to become southerly quickly during the early part of Tuesday morning. This will allow higher dewpoint air to stream northward, especially into parts of southern and central Oklahoma and western north Texas. High clouds (which have become almost a fixture in our sky lately) are expected to be thicker across southern parts of Oklahoma and north Texas Tuesday afternoon. However, deep enough mixing across parts of west central and northwest Oklahoma should allow for stronger winds and lower humidity to spread into that part of Oklahoma during the mid to late afternoon. This would result in near-critical to critical fire weather conditions for ~ 2 to 3 hours. For now we keep the Fire Weather Watch as is, as some of the southern counties could be excluded from a Red Flag Warning Tuesday afternoon. Also a little uncertain on momentum transfer Tuesday afternoon, so a Wind Advisory will not be issued at this time. However, the stronger wind gusts Tuesday afternoon should be coincident with the current Fire Weather Watch. && .LONG TERM... (Tuesday night through next Sunday) Issued at 251 PM CST Mon Feb 20 2023 Late Tuesday night through Wednesday morning, a fast-moving, lead shortwave trough will bring increasing chances of showers and thunderstorms. The 12Z HRRR appears to be the most aggressive in developing elevated showers and some storms overnight Tuesday (generally after 1 to 2 am), with even decent chances across west central and northwest Oklahoma. It appears better elevated instability may develop farther east into central and southern Oklahoma where precipitation coverage is expected to increase. The NAM soundings appear to be overdoing the amount of instability that develops, especially during the early part of Wednesday morning. However, if enough heating occurs during the later part of the morning, stronger storms are possible across mainly southeastern Oklahoma. Attention will again return to fire weather conditions for Wednesday afternoon, as clouds decrease and surface winds become gusty/windy. Deeper mixing will occur over a much larger area Wednesday afternoon with with a decent chance of seeing wind gusts in at least the 40-45 mph range over the western third of Oklahoma and parts of western north Texas. Stronger winds are anticipated to our west, so will add a mention of blowing dust during the afternoon. Afternoon humidity will likely approach or fall below 20 percent especially across northwest Oklahoma, so we will likely issue another Fire Weather Watch for Wednesday afternoon (similar geography plus maybe a few more northwest counties in Oklahoma. Part of the main trough across the western U.S. will move across the central Plains when vort max moves across Kansas and Nebraska overnight. A little suspicious how slowly a cold front moves across northern Oklahoma Wednesday night and the rest of the area Thursday. The air behind this front is certainly cold enough, so expect a faster frontal timing and perhaps lower highs for Thursday. Rain chances increase again Saturday with moisture return and a weak shortwave trough within southwest flow aloft. Perhaps a decent chance of widespread precipitation (rain/storms) with another trough Sunday into Monday. && .AVIATION... (00Z TAFS) Issued at 502 PM CST Mon Feb 20 2023 VFR conditions continue. A weak surface boundary will work south toward the Red River this evening and overnight with a light northeast to east wind north of the boundary and a light southwest wind to the south. This boundary will lift back to the north Tuesay morning and gradually dissipte with south to southwest winds increasing, especially during the afternoon hours. Some gusts over 30kts possible at WWR by late in the day. Othewise, abundant high clouds will continue to stream across the area. && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 44 72 58 72 / 0 0 60 70 Hobart OK 44 75 55 73 / 0 0 80 30 Wichita Falls TX 48 83 60 75 / 0 0 70 60 Gage OK 33 76 52 73 / 0 0 20 10 Ponca City OK 35 70 57 74 / 0 0 50 80 Durant OK 53 81 62 76 / 0 0 30 100 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...Fire Weather Watch from Tuesday afternoon through Tuesday evening for OKZ004-009-010-014>016-021-033-034. Fire Weather Watch from Wednesday afternoon through Wednesday evening for OKZ004>006-009>011-014>016-021-033-034. TX...None. && $$ SHORT TERM...06 LONG TERM....06 AVIATION...30
Area Forecast Discussion
National Weather Service Pueblo CO
342 PM MST Mon Feb 20 2023 .SHORT TERM...(This evening through Tuesday) Issued at 254 PM MST Mon Feb 20 2023 Key Messages: 1) Winds gradually diminish this evening and overnight 2) Breezy to windy on Tuesday, with high fire danger over the far southeast plains Still windy at many locations this afternoon with gusts of 35-45 kts common, though did cancel the mountain high wind warning early as most high elevation gusts have come down into the 50-60 kt range. Expect winds to continue to diminish this evening and overnight as surface pressure gradient briefly lessens and mountain wave dissipates, though still some 30-40 kt gusts possible higher exposed peaks of the mountains, while far eastern plains see south winds gusting 20-30 kts by morning as pressure falls resume east of the mountains. Still an occasional snow shower or flurry possible over the central mountains through the night, and some blowing snow likely, especially higher west facing slopes north of Cottonwood Pass. Min temps held up somewhat by winds/mixing, though many valleys may decouple enough to drop to seasonably cold readings. On Tuesday, winds increase again through the day, especially across the srn half of the area along the NM/OK borders, as upper jet begins to lift northward ahead of the deepening wrn U.S. trough. With snow melted and fuels becoming critical, have hoisted a red flag warning for far sern portions of the plains for Tue afternoon where wind/low RH combo is most favorable for increased fire danger. Will have to watch areas farther back west toward Trinidad and Pueblo for expansion of any fire highlight, as they will at least get close to Red Flag thresholds by late afternoon. Snow will gradually return to the Continental Divide through the day, though steadier/heavier snow will likely hold off until evening, so no highlight needed for the daytime hours. High temps will again soar to well above average levels at most locations, and some near 70f readings are possible over portions of the plains. .LONG TERM...(Tuesday night through Monday) Issued at 254 PM MST Mon Feb 20 2023 Models continue to be in good agreement with important minor differences in the details. Mostly, how far south a front pushes before stalling on the Plains Wednesday. Mountains areas will be very windy, along with areas down along the New Mexico border and appropriate highlights have been issued for these conditions and will be discussed below. Beyond mid week into early next week, differences arise with the next upper system. Tuesday night through Wednesday night...a strong upper storm system is forecast to drop south across the Great Basin Tuesday night. This will spread moderate to periods of heavy snow along the Continental Divide through the overnight hours, and persisting into Wednesday evening. Given the southwesterly flow, snow will be heaviest over the San Juan Range. In addition to the snow, winds will be very strong across the higher elevations as a speed max moves overhead. Gusts as high as 80 mph, if not stronger, are expected over the Mountains. Over the San Juans where the snow will be the heaviest, opted for a Blizzard Warning. Upwards to 2 feet of snow are forecast above 10 kft, with up to a foot for the Upper Rio Grande Valley. Winds gusting in excess of 80 mph will produce blow and drifting snow, with near white out conditions expected for travelers over Wolf Creek Pass. Those with travel plans through the San Juans should be prepared for very dangerous travel conditions Tuesday night through at least Wednesday evening. Further north, the southwesterly flow is less orographically favorable for heavy snowfall. Areas from the La Garita Range, north across the Sawatch Mountains will see up to 8 inches of wind blown snow. Wind gusts will reach near 80 mph producing very low visibilities on area roadways. Travel will likely be very dangerous across Monarch Pass. For the lower elevations of the upper Arkansas Valley of Chaffee and Lake Counties, snow totals will be less, mainly around 3 to 7 inches, if that much. There could be quite a bit of spill over off the Sawatch Range into the valley, and low visibilities due to very strong winds are likely. The advisory for these lower elevations is mainly due to expected travel impacts due to blowing snow and poor visibilities. Also opted for Winter Weather Advisories for the higher elevations of the Sangre de Cristo Range. Snow amounts will generally be in the 3 to 7 inch range, but winds will also be strong around 80 mph, producing blowing snow and hazardous travel conditions. For the San Luis Valley, strong southwesterly winds are expected on Wednesday. Gusts in excess of 60 mph are likely for the southern portion of the valley, and a High Wind Watch has been issued. Snow showers will also be possible, and the strong winds will likely produce areas of blowing snow and poor visibilities. In addition to the wind driven snow, sounding profiles indicate the potential for snow squalls, which would further produce poor visibilities on area highways. For the Plains...much will depend on where a cold front ends up. The GFS is most robust with the front, dropping it south along the I-25 corridor, and east, south of Highway 50 through Wednesday afternoon. The NAM is least aggressive with the front, stalling it on the Palmer Divide, and keeping it just north of the CWA. The ECMWF and Canadian runs are in the middle, with the front hovering from the Palmer Divide to just south of Lamar. With these model differences, went with the ECMWF and Canadian solutions. Temperatures over the Palmer Divide to just south of Lamar will be cold, with 30s through the afternoon. South of the front will be warm, with mid to upper 50s. In addition to warm conditions, strong westerly winds are expected over Las Animas and Baca Counties and a High Wind Watch has been issued. Winds could gust near 60 mph. Humidity values look to remain just elevated enough, falling to around 20 percent, so did not issue any fire weather highlights for Wednesday afternoon. Those with outdoor burning activities planned should postpone them until another day based on the strong winds. As for precipitation, snow is expected over the Palmer Divide. Snow accumulations of 1 to 4 inches are expected. Winds will not be quite as strong with gusts near 30 mph possible. How far south the precipitation makes it is the big question, and will depend on where the frontal boundary ends up. The GFS with its further south frontal position brings colder air south, and better snow chances into the Highway 50 corridor. The north NAM is dry south of the Palmer Divide. The ECMWF and Canadian, along with the NBM guidance and WPC coordination, wraps a bit of rain and snow south into the Pueblo area, with all snow by Wednesday late afternoon and evening as colder air filters into place. Snow accumulations look minor, from Pueblo, northeast to Kiowa County, with less than a half inch possible. If the GFS solution comes into play, slightly higher snow amounts may be possible. Snow and winds should dissipate Wednesday night into Thursday morning. Overnight lows Wednesday night will fall into the single digits to low teens across the Plains. Thursday through Monday...the upper system will continue to shift east away from the area, with broad southwesterly flow filling in across southern Colorado. This will lead to a gradual warming trend through the weekend, with highs warming from the 30s and 40s on Thursday, into the upper 50s to lower 60s for the weekend. Periods of light snow are expected along the Continental Divide through the weekend. The next upper storm system will move across the Desert Southwest early next week, bringing another round of snow to the Mountains, and possibly the Plains. Mozley && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 254 PM MST Mon Feb 20 2023 VFR conditions at all taf sites the next 24 hrs as winds diminish this evening and become variable in direction overnight. On Tuesday, w-sw winds will gust to 30 kts at KALS after 18z as deep mixing develops. Winds at KCOS and KPUB likely to stay light e-se until mid- afternoon as HRRR suggests weak eddy circulations near both terminals. After 21z-22z, stronger winds finally mix to the surface, with w-sw winds gusting to 30 kts expected. && .PUB WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 5 PM Tuesday to 5 AM MST Thursday for COZ058-059-061>063-073-075. Winter Storm Warning from 5 PM Tuesday to 5 AM MST Thursday for COZ060-066. Blizzard Warning from 5 PM Tuesday to 5 AM MST Thursday for COZ067-068. High Wind Watch from Wednesday afternoon through Wednesday evening for COZ070-071-088-094-099. Red Flag Warning from 11 AM to 6 PM MST Tuesday for COZ233-237. && $$ SHORT TERM...PETERSEN LONG TERM...MOZLEY AVIATION...PETERSEN