Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/17/21

Area Forecast Discussion
National Weather Service Denver/Boulder CO
715 PM MDT Sun May 16 2021 .UPDATE... Issued at 656 PM MDT Sun May 16 2021 Thunderstorms on the plains, mainly Lincoln County, beginning to wind down as instability decreases. After peaking at over 2500 j/kg this evening values have begun to fall, along with storm intensity. Still expect storms to persist, but have lost updraft strength and ability to produce hail and landspouts. Have blended in the latest available 23z HRRR pops to bring down precip chances. Still some lingering rain/snow showers moving through the mountains, and continued nonzero pops there through the remainder of the evening. N Central plains of Weld, northern Morgan & Logan counties are in relative min in pops, centered under surface high and solid cap. Relative minimum in pop chances late tonight are fleeting, with cooling temperatures aloft, some QG ascent, and return of daytime heating tomorrow morning POPs increase again. For temps, overnight lows look good but blended in some observed to even things out. && .SHORT TERM...(This evening through Monday) Issued at 256 PM MDT Sun May 16 2021 Scattered showers and storms are developing over the high terrain and should start moving out over the plains later this afternoon. Daytime heating was significantly limited in the foothills and adjacent plains by the persistent stratus since this morning, generally in the area around and north of I-76. A recent sounding from near Fort Collins showed a large capping inversion with about 130 J/kg of CIN. There may be enough lift from outflow from nearby convection for some isolated storms to initiate in this area but they would be weak and precipitation may also struggle to reach the ground. Models didn`t pick up on the early stratus well and aren`t picking up on the cap very well either. I have reduced temperatures, PoP, and QPF in this area through the evening to account for this, and it also reinforces the idea that severe weather will be limited to the area southeast of I-76 today where there is better instability. Scattered showers and storms will persist through the night with best coverage and intensity gradually shifting east with a potential MCV. Models are still showing an MCV developing over east-central Colorado tonight and moving northeast towards the Kansas border through Monday morning. The main impact with this system would be moderate to heavy rain on the eastern plains. More showers and storms are likely Monday afternoon and evening with increased vorticity advection aloft ahead of the cutoff low to our southwest as it advances east. The potential for severe storms still seems limited by a lack of instability and weak flow aloft however. .LONG TERM...(Monday night through Sunday) Issued at 256 PM MDT Sun May 16 2021 For Monday night and Tuesday, the broad upper low will meander slowly across southern Colorado but with only weak upward QG ascent with the low. Airmass will be mostly saturated with increasing/deepening northeast upslope flow with approaching low on Monday night. Expect the highest chances of showers in this Monday night and Tuesday morning time period. By Tuesday afternoon the low level flow shifts more southeast and upper low center is over south central Colorado. Still expect likely showers during the afternoon/evening, but instability will again be limited with more isolated thunderstorms. The weakening upper low will move across Eastern Colorado and into the central plains later Wednesday and Wednesday night with some drying and weakly subsident airmass. Chance of showers on Wednesday will see less areal coverage of storms but may be a bit more instability with possible better heating. Temperatures will be warmer on Wednesday with readings back around seasonal normals. For Thursday and Friday, a new strong upper low will move onshore from the Pacific and move into the northern Rocky Mountain region for Friday and Saturday. This will increase the southwest flow pattern aloft, somewhat drier air so expect more isolated coverage of late day storms. There could be better strength of storms across the far eastern plains of Colorado with deeper low level moisture expected to reside. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 656 PM MDT Sun May 16 2021 Not an easy forecast overnight. KDEN briefly went into VFR and near ILS mins, but have since dropped back to MVFR. Despite decrease in precipitation coverage low level moisture to remain in place overnight tonight, although challenge is in picking a ceiling height. Model soundings show ceilings at KDEN generally dropping to MVFR, with rain chances tapering off by midnight and renewing again late Monday morning. KAPA and KBJC stand a better chance for IFR ceilings overnight with a little elevation advantage. Wind forecast to shift around west to southwest overnight, southeast Monday morning, then by mid day an easterly upslope flow to continue low clouds. && .HYDROLOGY... Issued at 256 PM MDT Sun May 16 2021 There is still some risk of slowing moving storms producing moderate precipitation over the burn areas in the foothills through this evening. There is potential for development of an MCV and persistent showers on the eastern plains overnight through Monday morning. Moderate to heavy rainfall is possible under the MCV with a low flooding risk. The flash flood risk will be low on Monday night and Tuesday with more light to moderate rain with only weak instability. Expect lower areal coverage of storms on Wednesday but better heating may result in stronger storms for Wednesday afternoon. A drier airmass will be over the area Thursday and Friday with only isolated late day storms possible. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Hanson SHORT TERM...EJD LONG TERM...Entrekin AVIATION...Hanson HYDROLOGY...Entrekin/EJD
National Weather Service Hastings NE
701 PM CDT Sun May 16 2021 .DISCUSSION...(This evening through Sunday) Issued at 518 PM CDT Sun May 16 2021 Will state up front that given the time spent on this shift helping deal with the localized-but-extensive flooding in our far southern CWA (from overnight/early AM heavy rain), the bulk of the "routine" 7-day forecast did not get the attention it normally deserves. As a result, the main focus here (as far as attempted details) will only be on the next 24 hours. General overview of the entire 7-day forecast: - The very active weather pattern continues: We look to remain in our ongoing/active weather weather pattern for several more days, as literally every day/night forecast period features at least some rain chance/PoPs somewhere in our coverage area (CWA). Of course, not all areas will receive rain every 24 hours, so please keep in mind that the forecast likely reads/looks wetter than it actually is. That being said, latest national WPC QPF guidance pegs most of our CWA for GENERALLY an additional 1-2" of rain over the course of the week, with noticably higher amounts quite possible wherever heavier thunderstorms might hit. Although it`s very difficult to pin down precip details in this pattern, a few of the overall-drier periods currently look to be centered around Thursday-Friday, as in theory we should spend most of this time "in between" upper level forcing. - Severe storm/excessive rainfall potential: Thanks mainly to seasonably weak-to-modest deep layer wind shear and lack of a focused upper level system moving through the region, there are no particular periods that "scream" higher- end/widespread severe weather. That being said, several upcoming afternoons/nights could feature at least a few strong to severe storms, including right away this afternoon evening (mainly pre- midnight) and then perhaps again late Monday afternoon-night especially in our far southern zones. SPC has most of our CWA in a Marginal Risk for this afternoon-evening and clips a Marginal into our far south for Monday, but latest SREF severe probs suggest that Monday`s Marginal in our area could be on pretty shaky ground with better instability clearly focusing south of our CWA. Although still a few days out, would not be surprised to see our next Marginal risk type setup be Wednesday as a low amplitude disturbance is slated to lift through the region from south- southwest to north-northeast. But as stated here yesterday, this is truly a "take it one day/night at a time" weather pattern for assessing severe storm potential, as so much could depend on mesoscale influences/boundary positions influenced by possible convection from the night before. - Temperature overview: Very little in the way of noticeable change from previous forecast, as we continue with a fairly seasonable/typical for mid- late May pattern, with highs on most days in the 70s, but ranging from mid-upper 60s on days such as Monday when extensive clouds are expected, to perhaps some low 80s during the Thursday-Sunday time frame. Overnight lows on most nights are aimed well into the 50s or low 60s, so slightly above normal for this time of year. Taking stock of the current/recent weather scene as of 430 PM: First off, see separate HYDROLOGY section below for a recap of the localized-but-extensive flooding in our far southern CWA this morning. Otherwise, today has seen a varied mix of departing lighter rain showers, followed by a multi-hour period of dry weather for most locations, and now most recently (especially past hour) followed by a redevelopment of very "random", slow-moving showers/storms particularly in/near our KS zones. In the mid-upper levels, water vapor satellite and short term model data confirms seasonably-weak, broad west-northwest flow, with 3 main mesoscale waves (MCVs) of note in/near our that has departed east into western IA, another shifting east along eastern portions of the OK/KS border and another very subtle one drifting east through north central Nebraska. At the surface, if anything today featured probably a bit more partial sunshine than expected, although high temps are on track to end up with a decent range from mid-upper 60s north-northeast (where clouds were most pervasive) to mid- upper 70s far southwest. Breezes have generally averaged 5-15 MPH today, with direction largely easterly after being more southerly at times earlier in the day. A weak effective arm front is positioned very near the far southern edge of our CWA (separating a more southerly wind direction farther south from a more easterly one in our area). Now focusing solely on some attempted details just for the next 24 hours: Late this afternoon-tonight: Up front, the one main difference between last evening-night and this evening-tonight is that there will be no strong/focused low level jet aimed into our CWA. As a result, the overall coverage of rainfall/thunderstorms should be considerably more isolated/spotty, and probably most concentrated before midnight (more diurnally-driven) as opposed to after midnight. That being said, especially our far southwestern zones could be clipped by some very late night/early morning activity that could clip our area out of northwest KS. However, the primary concern over the next 7-9 hours or so (mainly through midnight) will be on the potential for fairly spotty and potentially a few strong/severe storms being driven mainly by daytime heating/instability in a fairly weak shear environment. Based on the latest high-res models such as HRRR/NamNest and given the position of the aforementioned MCVs and position of the weak warm front near our far southern CWA border, probably the overall-highest chances for spotty storms the next several hours will favor our KS zones (closest to warm front) and also our northern zones (mainly north of I-80) in closest proximity to the weak MCV. For sure, the highest instability (mixed-layer CAPE 1000-2000 J/kg) is in our southern zones, but deep layer shear is quite weak by May standards (only 25-30KT at best). So, although storms will be spotty, they will be slow moving and could easily dump 1+" of rain in a short time, and perhaps be capable of isolated downburst winds/marginally-severe hail (to around quarter size). Fortunately for our ongoing hydro issues in KS zones, the latest HRRR (and supported by radar trends) suggest that most (not all) convection and localized heavy rain this evening should focus just south of our CWA. Getting past midnight, expect any kind of stronger storm/heavy rain threat to largely fade. However, widespread low clouds are expected to fill in, and there are increasing signs of perhaps some Monday morning fog issues. Cannot rule out at least localized dense fog, but for now have at least gotten the ball rolling with a basic, CWA-wide "patchy fog" introduction to the forecast. Low temps tonight are aimed mid-upper 50s. Monday daytime: Despite carrying at least small PoPs area-wide, for most of the CWA this should be a predominantly dry day, aside from any possible morning fog and/or light drizzle. Any potential for "true" heavier showers and/or storms should mainly be confined to our far southwestern CWA, in the proximity of a weak shortwave lifting up from the southwest. However, even at this close time range, models disagree on whether this potentially steadier rain will actually get into our southwestern zones or perhaps remain just BARELY to our west within northwest KS/southwest NE. Hopefully night shift can get a little better handle on this, as the last thing we need is any concentrated rain in especially the southern Rooks/Osborne county vicinity. Again though, overall looks like a very cloudy start to the day perhaps improving to mostly cloudy/pockets of partly cloudy with time, and overall-dry most areas. Breezes will average around 10 MPH from a generally east-northeasterly direction, and high temps were nudged down slightly, with most areas only expected to top out in the 66-70 range. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday) Issued at 622 PM CDT Sun May 16 2021 A few -TSRAs will be possible through the evening hours, although convection is expected to be scattered enough that decided to only include a VCTS at both sites. Later in the night as the chance for storms shifts south...CIGS are expected to lower to IFR or even LIFR levels as low stratus and fog develops across the area. This fog should last into the morning hours Monday...and while CIGS should lift back to MVFR levels...generally cloudy skies will persist all day. Overall...expect generally easterly to northeasterly winds near 10 KTS (outside a -TSRA) through the period as surface low pressure remains across the high plains with surface high pressure remaining across the great lakes region. && .HYDROLOGY... Issued at 518 PM CDT Sun May 16 2021 Recap of Sat night-Sun AM heavy morning: Unfortunately, localized heavy rain/flooding was a bigger issue than expected here 24 hours ago, but it was VERY localized. The vast majority of our CWA received "manageable" rain amounts in the 0.25-1.50" range. However, small pockets of heavier amounts mainly 2-4" occurred in very small portions of mainly Dawson/Harlan counties in our Nebraska CWA (minor flooding at worst), but the "main event" by far was a concentrated, west-east swath of widespread 3-5" (localized/unofficial report of around 8") that fell directly on the Paradise Creek basin in southern Rooks/southwestern Osborne counties in north central KS. This prompted extensive/serious flooding along the Paradise Creek, particularly affecting the town of Natoma where there were reports of 100 residents displaced this morning. Although water levels have started to recede since, we continue Flood Warnings into at least tomorrow for both the Paradise Creek and also the South Fork Solomon River in northern Rooks/northwestern counties, which also went into flood due mainly to runoff from smaller creeks feeding northward from southern parts of the county. Looking forward next 12-18 hours: Fortunately, we are not expecting a repeat of concentrated/extremely heavy rainfall this evening-tonight, mainly due to lack of a strong/focused low level jet. That being said, the potential exists for more spotty "random" thunderstorm development especially between late this afternoon and midnight (mainly diurnally-driven activity), that could easily dump 1+" of rain in a short time. Based on a few of the latest high-res models, unfortunately our KS zones probably stand the best chance of seeing some of this spottier/heavier activity, so we`re essentially "crossing our fingers" that it largely avoids southern Rooks/Osborne counties (most of the remainder of north central KS) can handle more rain). Earlier considered issuing a Flash Flood Watch just for those counties, but with 24-hour ensemble probability matched mean QPF from the 12z HREF only suggesting the vast majority of that area should average less than 1" of rain this afternoon-tonight, opted against a Watch and we will simply keep an eye on things and update existing/issue new Advisories/Warnings as needed. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ DISCUSSION...Pfannkuch AVIATION...Rossi HYDROLOGY...Pfannkuch
Area Forecast Discussion
National Weather Service Goodland KS
537 PM MDT Sun May 16 2021 .SHORT TERM...(This evening through Monday night) Issued at 330 PM MDT Sun May 16 2021 Overview: Modest southwest flow aloft (today) will back to the SSW-S on Monday.. as an upper level low (presently situated invof Las Vegas, NV) progresses eastward to the 4-Corners/Desert Southwest. Today-Tonight: Challenging convective forecast. In a muttled synoptic regime.. characterized by weak low/mid-tropospheric (SFC-H5) flow.. the evolution of the low-level (SFC-H85) pattern and majority of forcing (i.e. not directly assoc/w convection) will, once again, largely be dictated by mesoscale features. Per 20Z visible satellite imagery and regional surface observations.. a weak, ill-defined surface low was present over portions of eastern CO and northwest KS. This feature appears to be centered invof Lamar, CO.. extending northeast toward Burlington and Goodland. Considerable low overcast (areas of fog, even) persist on the northwest periphery of this feature.. along the Colorado Front Range and portions of the Palmer Divide. Additionally, a WNW-ESE oriented convergence zone (extending from St. Francis-->Hill City-->Russell-->Salina) was evident in visible satellite imagery (as a narrow corridor of agitated Cu), along which isolated convection has recently developed near Russell/Salina. Mesoanalysis data indicates moderate instability (1500-2500 J/kg mlcape) is present over the majority of the area, strongest invof Tribune-Syracuse-Johnson, though deep-layer shear remains on the marginal end of the spectrum (20-30 kt). Simulated reflectivity forecasts via the HRRR and NAM NEST suggest that convection currently developing along the Raton Mesa and portions of the Colorado Front Range (south of Denver) will gradually increase in coverage/intensity late this afternoon.. eventually merging into a cluster that progresses slowly E-ENE across the CO/KS border this evening.. perhaps stalling over northwest KS tonight. Organization will largely be multicellular in nature.. with marginally severe hail and wind gusts up to 65 mph the primary hazards.. transitioning to locally heavy rain and flash flooding as activity coalesces and grows upscale into a cluster (or clusters) after sunset. A Flash Flood Watch remains in effect for Wallace, Greeley, Wichita, Logan and Gove counties, where 1-6" of rain fell late yesterday evening/night.. and additional heavy rain may rapidly lead to flash flooding. Mon-Mon night: Flow aloft will gradually back to the SSW-S in this period, as the deamplifying upper low progresses eastward into the 4-Corners/Desert Southwest. Aside (perhaps) from an increasing potential for small amplitude waves aloft.. forcing will largely be driven by convective/mesoscale features.. i.e. every bit as challenging as the past few days with regard to temperatures, cloud cover, convective development/coverage/ evolution/hazards. Bottom line.. another day of widespread convection appears likely. .LONG TERM...(Monday night through Sunday) Issued at 203 PM MDT Sun May 16 2021 Chances for afternoon/overnight storms remain for the entire week. High temperatures are still forecasted to be near average through Wednesday before going slightly above average to finish the work week. The pattern through the work week is still looking to be the same to previous forecasts. Tuesday and Wednesday an upper cut-off low approaches the area before diffusing into the larger flow late Wednesday. From that point forward, a upper ridge sets up over the Eastern CONUS with a upper trough over the Western CONUS that puts the Tri-State area in southwest flow aloft. Near the surface, lower MSLP remains over the Rocky Mountain Region with higher surface pressure off to the east. Initially, the lower pressure is to the south of the area until Wednesday when it flips to north of the area. The weekend then may bring a low off the Front Range. What this means is two different sets of expected conditions. Tuesday and Wednesday are forecasted to be relatively cooler and cloudier with high temperatures near 70 and chances for rain through most of the day. Wednesday may be drier and warmer as the overall weather pattern shifts during the day. Thursday through Saturday is expected to be warmer and confine the chances for rain and storms more into the afternoon and evening hours. Highs during the time period are expected to be near 80. Cloud cover will likely not be as persistent with sun during the daytime hours. As for rain chances, guidance is still persistent on keeping moisture available to the area though how much is uncertain given the change in pattern. Synoptic lift will be questionable each day as upper shortwaves may pass through the area and surface low pressure centers are far enough from the area to have little effect. However, there could be boundaries such as lingering outflows from previous convection or maybe even a dryline. Also, with less clouds and more heating during the daytime hours, enough CAPE may develop to fire off storms. So all of this contributes to a greater chance during the afternoon and evening hours with the potential for severe weather each day depending on how much instability develops in the area. It is too uncertain to determine each day right now, but will continue to monitor during upcoming forecasts. So expect dry days with storm chances increasing during the afternoon hours and the potential for some to be severe during the end of the week. Some showers may linger through the night and into the morning hours the next day but chances are uncertain right now. Sunday may bring a cold front to the area though guidance has been moving this front around. Guidance also has not agreed on how/when the upper trough will move from its position in the Western CONUS. Ensembles also are fairly uncertain, but more members have it moving east during the day Sunday. Currently am keeping Sunday warm but will need to monitor timing/location changes of the front. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 533 PM MDT Sun May 16 2021 VFR conditions are expected to continue through the 00Z TAF period with potential for thunderstorms this evening into the early morning hours over the MCK and GLD terminals. Thunderstorms are expected to move into NW Kansas from western Colorado and west- central Kansas. Confidence remains lower for storm activity over the MCk terminal; however, due to the potential kept VCTS in the TAFS through 15Z. Light ESE to ENE winds will prevail through the TAF period. Of course, gusty/erratic winds can be expected in vicinity of any thunderstorms. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...Flash Flood Watch through late tonight for KSZ027>029-041-042. CO...NONE. NE...NONE. && $$ SHORT TERM...VINCENT LONG TERM...KAK AVIATION...KMK
Area Forecast Discussion
National Weather Service Grand Rapids MI
743 PM EDT Sun May 16 2021 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 254 PM EDT Sun May 16 2021 - A few showers across north central Lower MI this evening - Greater rain chances late Tuesday into Wednesday - Fire weather threat remains significant && .DISCUSSION...(This evening through next Sunday) Issued at 254 PM EDT Sun May 16 2021 -- A few showers across north central Lower MI this evening -- There will be a chance for relatively brief rain showers in the general vicinity of Clare County late this afternoon into early evening. Forecast details: CAM guidance, particularly recent HRRR runs, have been fairly consistent with shower development in the mentioned area. This is supported by water vapor imagery, which shows an approaching weak PV disturbance currently entering northwest WI. Additionally, the 12Z APX sounding indicates impressive cold temperatures aloft //-23C at H5// which will mean favorable lapse rates with gradually decreasing clouds helping afternoon insolation. -- Greater rain chances late Tuesday into Wednesday -- For Tuesday night into Wednesday there are increasing chances for showers and even thunderstorms. As noted previously, Monday and Monday night look dry and scattered showers remain possible from Wednesday into the weekend. Forecast details: 16/00Z ECMWF ensemble is notably wetter with QPF for the 24 hours between Tuesday evening and Wednesday evening. SPC gives us a chance for thunder into Wednesday morning as well. From Wednesday onward, forecast soundings feature weak conditional instability associated with deep moisture and nearly moist adiabatic lapse rates. It was noted previously that no significant forcing mechanisms are foreseen, but it wouldn`t take much mesoscale forcing (such as lake breeze circulations) to generate at least some spotty precipitation in this environment. -- Fire weather threat remains significant -- Precipitation amounts with any rain occurring Tuesday night into Wednesday would most likely total under a quarter of an inch. This would not make much of a dent in the drought. Minimum relative humidities towards the end of the week look to be around 40 percent, but this could easily go lower if highs are able to reach 90 degrees. Additionally, winds from the southwest will be increasing with gusts perhaps approaching 30 mph by Friday afternoon. How the fire threat evolves depends in part on mid-week precipitation, but we are not seeing anything yet to reduce the concern. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 737 PM EDT Sun May 16 2021 TAF sites in Southwest Lower MI are looking at VFR conditions through Monday. A few showers could develop Monday afternoon but confidence that they will impact a TAF site is not high enough to include them in the forecast. The pressure gradient remains weak so the wind will largely remain under 10 knots through the forecast period. && .MARINE... Issued at 254 PM EDT Sun May 16 2021 No changes to previous thinking. Winds will be either light or offshore through the period which will limit wave growth closer to shore. Marine fog becomes a possibility starting around Wednesday as we begin to see dewpoints making a run at 50 degrees over the colder water surface. By the end of the week, with land temperatures getting well into the 80s, we will be seeing a lot more active lake breeze days. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && $$ SYNOPSIS...TJT DISCUSSION...TJT AVIATION...MJS MARINE...TJT
Area Forecast Discussion
National Weather Service Wichita KS
1014 PM CDT Sun May 16 2021 .UPDATE... Issued at 1010 PM CDT Sun May 16 2021 Latest high rez RAP model data suggests that low level moisture transport will continue over NE OK and SE KS for at least the next few hours, so expect showers to continue to move across this area. But as the overnight continues, expect the moisture transport to veer east into SW MO, which will lead to the showers diminishing or ending over SE KS early Mon morning. NOt expecting much thunder with this activity as most of the elevated instability remains to the south of the area in OK. For the rest of the area, think most locations will remain dry overnight, as elevated instability stays to the south of the area, with very little moisture transport. Plan on leaving in a low pop over south central KS, in case a rouge shower can pop up. Expect widespread cloud cover overnight, as low level moisture remains high. Ketcham && .SHORT TERM...(This evening through Wednesday night) Issued at 325 PM CDT Sun May 16 2021 Currently have an upper circulation lifting across north central OK with a closed upper low spinning over southern CA. At the surface, there appears to be a weak stationary front/outflow boundary stretching from south of Kansas City to near Salina. Storms continue to linger near this weak boundary late this afternoon as the entire area remains unstable with around 1500-2000J/KG of CAPE. Will also see showers/storms become more widespread as the upper impulse lifts into south central/southeast KS early this evening. After around 02z, feel that southeast KS will be the only area still seeing showers/storms as the activity over central KS is more diurnally driven. Main threat with showers/storms will remain heavy rainfall and flooding due to slow movement of storms. With minimal shear not too impressed with large hail potential but can`t rule out a wet microburst. Additional storms are once again expected to develop out over the High Plains late this afternoon/early evening and will track east overnight. Confidence is low on how far east this activity will make it due to weaker steering winds along with less 850-700mb theta-e advection than we`ve had the last few nights. So for most of the night, feel we should see a lull in activity with the exception of southeast KS as the upper impulse continues to slowly lift into MO. Not overly impressed with precip chances during the day Mon as much of it will depend on how far east High Plains activity makes it and if there are any MCV`s associated with this activity. Meanwhile, the more pronounced upper impulse will be continuing to track across MO. Widespread convection is expected late Mon afternoon/early evening over the TX/OK Panhandle with this activity forecast to track east and northeast Mon night. The eastward progression of this activity will be aided by better jet dynamics and upper diffluence spreading east as the upper low rotates into NM/southern CO. Would expect some showers and storms to linger across the area Tue morning with any convectively induced impulses having a big impact on storm chances Tue afternoon and evening. .LONG TERM...(Wednesday through Sunday) Issued at 325 PM CDT Sun May 16 2021 By Wed morning weak upper trough will extend from eastern CO into eastern NM with both ECMWF and GFS agreeing on a weak upper impulse lifting across the Ozark region. With plenty of instability around can`t completely rule out a few storms about anywhere on Wed, but feel the better chances will be tied to the piece of energy tracking over the Ozark region. Good model agreement on a deep upper trough digging over the West Coast for Thu into Fri with some upper energy lingering under the upper ridge from IA into Eastern OK. This feature will be the main focus for showers and storms Wed into Thu. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 629 PM CDT Sun May 16 2021 A rather complicated aviation forecast, as a quasi stationary boundary remains draped across central KS, with scattered TSRA near the KRSL and KGBD taf sites. So will go with VCTS and tempo TSRA for this chance across central KS. Think most of the convection across central KS will be diurnally driven with storms diminishing after sunset. The only exception may over over SE KS, where increasing low level moisture transport may increase scattered TSRA near KCNU for late this evening or towards midnight. As the evening and overnight progresses, the MVFR cigs will gradually decrease to IFR for most locations, as low level moisture remains very high. Think the IFR cigs will remain for most of the overnight hours into Mon morning. Expect to see a slight increase in cigs for Monday with cigs generally becoming MVFR. Ketcham && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 60 75 60 75 / 20 30 60 60 Hutchinson 60 74 58 74 / 40 30 60 60 Newton 59 74 59 74 / 40 30 60 60 ElDorado 59 74 60 74 / 40 30 50 70 Winfield-KWLD 60 76 61 76 / 20 30 60 70 Russell 57 70 55 74 / 50 40 60 70 Great Bend 57 71 56 73 / 40 40 60 70 Salina 58 73 58 75 / 50 50 50 70 McPherson 59 73 58 74 / 40 40 60 70 Coffeyville 60 75 61 76 / 80 40 50 80 Chanute 59 74 61 76 / 70 60 50 70 Iola 59 74 60 76 / 70 60 50 70 Parsons-KPPF 60 74 61 76 / 70 50 50 80 && .ICT WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Ketcham SHORT TERM...RBL LONG TERM...RBL AVIATION...Ketcham
Area Forecast Discussion
National Weather Service North Platte NE
643 PM CDT Sun May 16 2021 .SHORT TERM...(This evening through Monday night) Issued at 333 PM CDT Sun May 16 2021 The disturbance and weak closed upper circulation which tracked through western NE overnight and today will move east of the area this evening. The main weather feature through Monday night will be the closed upper low currently centered over southern Nevada. A surface low is centered over east central CO, with a stationary front extending across northern KS. POPs were trimmed back for tonight, with the best chances across southwest NE overnight. This area will be in closer proximity to a disturbance moving from eastern CO into western KS overnight. With PWATs still ranging near or above 0.90 inch near and south of I80, and weak steering winds, locally heavy rain is again possible with any storms. Latest HRRR, RAP and SREF also indicated fog development across the Sandhills later tonight through mid morning, with patchy to areas of fog forecast. Visibilities could fall below a mile in some locations. On Monday, a disturbance will lift slowly northward from eastern CO and western KS. This will bring increasing chances for showers across the area by afternoon, along with a chance for thunderstorms across southwest areas. The latest models show associated lift will weaken as if lifts north. The highest POPS for 40 to 50 percent across southwest NE, to only a slight chance northern NE. Mainly cloudy skies and an east to southeast wind will limit highs to the mid 60s. Monday night, the closed upper low will move into CO and NM, with a disturbance lifting from northwest KS into southwest NE. This will bring likely POPs into far southwest zones after midnight. Weak lift and and a moist atmosphere across the remainder of the area to provide a chance for showers and a few storms into north central NE. .LONG TERM...(Tuesday through Sunday) Issued at 333 PM CDT Sun May 16 2021 The closed upper low will slowly northward Tuesday through Tuesday night while the disturbance to its east brings the best POPS to western NE on Tuesday. Locally heavy rainfall is possible. Wednesday into Wednesday night the closed low will open up and lift northeast through western NE. Locally heavy rain once again possible Wednesday afternoon and evening. Another deep closed low will drop into the western U.S. Thursday and Friday as a strong upper ridge remains anchored over the southeastern U.S. This will bring an amplified south southwest flow at H500 with winds at that level up to 40KTs. This looks favorable for severe storms to form Friday afternoon and evening, and possibly again Saturday afternoon and evening. Highs to reach around 80 Thursday and Friday, and possibly into Saturday and Sunday if the Pacific frontal passage is delayed. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 643 PM CDT Sun May 16 2021 Isolated rain showers and thunderstorms are expected through the evening. Stronger storms with gusty winds could be possible along and south of I-80 impacting KLBF. Rain gradually diminishes by 06Z with ceilings remaining below 1000 feet. Some patchy fog may even be possible at both sites. Any fog will diminish after sunrise with ceilings struggling to rise above 2000 feet for the rest of the TAF period. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Roberg LONG TERM...Roberg AVIATION...Kulik
Area Forecast Discussion
National Weather Service Elko NV
148 PM PDT Sun May 16 2021 .SYNOPSIS...Scattered showers and thunderstorms, some strong with small hail and gusty winds. Weather systems triggering these storms shifts east on Monday bringing drier weather to northwest Nevada, but some showers and thunderstorms persist over eastern Nevada. A colder weather system arrives later in the week and brings more showers and thunderstorms, and possibly accumulating snow in the mountains. && .SHORT TERM...Tonight through Tuesday evening Easterly flow this afternoon with storm movement from east to west due to closed low circulation centered over southern NV. Best bulk shear is east of Nevada over western Utah, but some shear exists for isolated strong storms capable of producing small hail and gusty winds (and even one observed funnel cloud). HRRR trends suggest convection over White Pine County collide with storm clusters originating over Elko County. The merging of these storm clusters could bring some significant rain to spots in Lander and Eureka counties later this afternoon and early evening. Rainfall amounts could be around one half inch or more. Air mass stabilizes later this evening, although isolated convective activity may prevail through the evening across northern NV. Environment favors more pulse storms, but aforementioned colliding outflow boundaries may spawn stronger convection. Closed low core moves downstream and crosses Arizona on Monday. Some moisture and instability does persist over eastern Nevada, primarily White Pine and northeast Nye counties and will be diurnally driven. Nevada will be in between weather systems on Tuesday, generally warm with highs in the 70s to lower 80s. Some buildups may occur toward the Utah border, otherwise sunny across the region. .LONG TERM...Tuesday night through Saturday. Tuesday night will be a bit of a transition as model simulations continue to show a longwave upper low over British Columbia, Canada. The overnight for Tuesday will be fairly quiet with lows in the 40s and light winds. On Wednesday, a piece of energy will be diving to the southeast and head towards northern and central Nevada. Winds will be breezy during the day but should not be too strong. Some light showers and possibly thunderstorms will be possible over the area but amounts look to be light. Afternoon highs will be in the low to mid 70s. The upper low will continue its progression towards the area during the overnight with the threat for showers during this period increasing. Right now, snow levels appear to be at or above 7000 feet during the day. Some of the heavier showers could temporarily drop the snow levels to ground level but accumulations are not expected during the day. Overnight lows will be in the upper 30s to mid 40s. The pesky upper low is forecast to close off on Thursday, basically spinning around the state. Conditions will be much cooler temperature-wise, with readings in the 50s and 60s. Off and on showers, with isolated embedded thunderstorms, will be the rule. Due to the convective nature, hard to really determine how much rainfall is expected, but most areas should see about 0.10 inches or less. For the overnight Thursday into Friday, temperatures will continue to drop as simulations continue to show the upper low spinning overhead. Snow levels are expected to drop to the valley floors during the overnight and we could see some minor accumulations along the summits and passes. Will need to keep an eye on this event as it draws near. Overnight lows will drop into the 20s and 30s. The upper trough will continue to remain overhead based on latest guidance as a strong upper ridge sits over the southern Gulf Coast. This will mean a continuation of showery weather and cooler than normal temperatures. && .AVIATION...A system continues to pass over NV bringing showers and thunderstorms to all terminals for the next few days. Right now there is showers with a few embedded thunderstorms that will persist through the morning hours, mainly impacting the northern NV sites of KEKO, KBAM, and KWMC. The thunderstorm chance overnight is not high enough to reflect in the TAFs thus only the showers are reflected. Sunday afternoon to evening will see more thunderstorms that will impact all terminals. These thunderstorms can lead to heavy downpours, erratic strong gusty outflows, and hail. A few of the thunderstorms may be strong and even severe which can produce even stronger winds, larger hail, and heavier downpours. KEKO and KBAM have the best chances of seeing these stronger thunderstorms. The thunderstorms and showers will likely cause mountain obscurations through NV. There will once again be some threat of nocturnal convection during the overnight hours of Sunday into Monday. && .FIRE WEATHER... Wet thunderstorms this afternoon and evening across the forecast area today. Isolated areas will receiving soaking rains, the best rainfall expected over fire zone 427. Convective activity diminishes overnight, but additional showers and storms are expected over eastern Nevada (drier over northwest Nevada), fire zone 425 having the best chance for thunderstorms. Showers are expected to accompany storms. Drier and sunny weather is expected on Tuesday. Another weather system brings another round of showers and thunderstorms, possibly accumulating snow in the mountains above 7000 feet. No critical fire weather conditions expected this week. && .LKN WATCHES/WARNINGS/ADVISORIES... None. && $$ 88/86/88/86
Area Forecast Discussion
National Weather Service Marquette MI
634 PM EDT Sun May 16 2021 .SHORT TERM...(This evening through Monday) Issued at 342 PM EDT SUN MAY 16 2021 Water vapor imagery and RAP upper level analysis showed a cutoff low over southern California with ridging over the Pacific Northwest. Downstream the flow was more zonal with a shortwave moving through southern Saskatchewan and other shortwaves evident in the water vapor imagery over the central and southern plains. Low level moisture streamed north into the U.P last night into this morning with fog close to the MI/WI border and low stratus over much of the central and east. Much of the low clouds and fog eroded though the late morning hours with fair weather cumulus developing this afternoon, though some stratus had hung on in the east. The cutoff low over southern CA will drift to the Four Corners area of the Southwest U.S through Monday. A trough will approach the Pacific Northwest with the downstream ridge beginning to becoming more amplified over the northern Plains and western Upper Great Lakes. This will result in continued pleasant temperatures across the area on Monday. For tonight it looks like winds will be just strong enough to keep the interior a little warmer than last night, with lows generally in the 40s across the U.P. The models are very aggressive with the fog over northern Lake Michigan and the Bay of Green Bay, spreading inland overnight in the east. I don`t have a lot of confidence in this solution. Models have been overly aggressive with the fog / low vis. Moisture advection also decreases overnight with models showing a thinning marine layer. Current thinking is that there will be areas of fog but it might not be as widespread as the models are showing. Monday will continue warm with highs approaching the low 80s for the interior west. The operational NBM is running in the 5th percentile of the distribution, with the NBM median several degrees warmer. The warmer solutions seem unlikely with 850 mb temperatures only rising a few degrees from today to Monday. A weakening pressure gradient should allow for a lake breeze to push off of Lake Superior and well inland during the afternoon. HREF members have backed off on instability and convection along the lake breeze boundary. Not ready to remove the mention of thunder from the grids just yet, we will have to see what happens with subsequent model runs. RHs will fall to the mid 20s Monday afternoon over the interior west and central however winds will remain light. .LONG TERM...(Monday night through Sunday) Issued at 359 PM EDT SUN MAY 16 2021 The main story of the extended forecast is a prolonged period of summer like weather expected this week. The biggest change from recent/ongoing warmth is a substantial increase in moisture/humidity by Wednesday and a corresponding increase in chances for much needed precipitation. Thus, the warm and dry pattern should transition to a warm and less dry pattern by late this week. Long-range ensemble guidance indicates this stretch of summer-like weather will end with a potent cold front around May 23rd/24th, but take that with a grain of salt. At the beginning of the extended period (00Z Tuesday) the upper level pattern will be characterized by a cut off low over the 4- corners area and ridging from Florida north-northwest into the Canadian Praries. Potent troughing digs into the Pacific NW on Tuesday and Wednesday resulting in an amplifying western trough and eastern ridge (-PNA) pattern. This pattern results in deep SW flow aloft transporting rich Gulf of Mexico moisture into our CWA. Additionally, the cut off low over the 4-corners area appears to get sheared into a series of low amplitude shortwaves resulting in a prolonged period of low PoPs. Elevated moisture increases on Tuesday as a surface warm front approaches from the southwest, which should result in cloud cover that limits surface heating/maximum temperatures. The surface warm front surges across the area early Wednesday morning with at least a few light rain showers along the front. A rapid increase in low level moisture south of this front should result in areas of dense marine fog, especially over Lake Michigan and adjacent shorelines. NAM guidance supports this with a saturated sounding and a sharp boundary layer inversion at ESC/ISQ on Wednesday morning. 09Z SREF highlights the Garden Peninsula with greater than 75% chances of 1 mile vsby and even higher probs of low stratus. Since there`s a decent plume of marine fog/stratus today with dew points in the upper 40`s it stands to reason that the marine fog situation will get worse before it gets better. Despite reasonably high confidence, I struggled with adding fog to the grids. Generally warm temperatures and Pwats consistently above the 90th percentile late this week suggest persistent precipitation chances. However, the forcing mechanisms are diffuse without a clear signal for widespread precipitation. This suggests a diurnal precipitation pattern may dominate with lake breeze boundaries forcing afternoon shower and thunderstorm development. Model soundings suggest fairly widespread cloud cover that would limit destabilization, but cloud breaks should occur. NBM PoPs favor northwest portions of our CWA, perhaps because moist southerly flow off Lake Michigan results in persistent fog and stratus across the east. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 634 PM EDT SUN MAY 16 2021 VFR conditions will prevail though the TAF period. Gusts to 20 knots will be possible at KCMX on Monday by mid-morning as daytime heating mixes into somewhat stronger winds aloft. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 342 PM EDT SUN MAY 16 2021 High pressure will remain over the Great Lakes for the next several days, limiting wind gusts over the lake to 15 knots or less into much of next week. Increasing moisture could result in areas of dense fog at times though the week but confidence is low. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... Dense Fog Advisory until 11 PM EDT this evening for LMZ248-250. && $$ SHORT TERM...NL LONG TERM...EK AVIATION...07 MARINE...NL
Area Forecast Discussion
National Weather Service Shreveport LA
952 PM CDT Sun May 16 2021 .UPDATE... Tonight`s forecast was updated to account for the northeastward progress of new convection that maintains milder temperatures overnight. Otherwise, no additional forecast updates were necessary. /16/ && .PREV DISCUSSION... /issued 653 PM CDT Sun May 16 2021/ AVIATION... For the 17/00Z TAF update, sloppy MVFR/IFR flight conditions will continue well through the period as -TSRA/-SHRA invades our airspace from the west. This convection will gradually reach KMLU by 17/03Z and diminish before the second wave of -TSRA/-SHRA arrives across our airspace from the west mostly after 17/12Z. This second wave will reinforce MVFR/IFR cigs/vis through the end of the period. /16/ PREV DISCUSSION... /issued 258 PM CDT Sun May 16 2021/ SHORT TERM.../This afternoon through Monday night/ Well our short run of dry weather has already ended for East Texas with a line of showers and isolated thunderstorm activity edging into Clarksville, Tyler and Jacksonville at this time. All this activity is moving slowly Eastward at 25 mph. Rain cooled low to mid 70s are lining up for our far west East Texas counties. Elsewhere, low to mid 80s and breezy. Another cluster of showers and thunderstorms is near Toledo Bend dam now and is lifting more northward. HRRR gets this up to Shreveport and Bossier before sunset. A strong upper low is in the desert southwest of the U.S. and will likewise be moving slowly to the ENE. This upper low has now sent the first of many impulses that will make for an all wet work week coming. SE winds will persist for days on the surface keeping us muggy and loaded moisture wise for new storm production. Meanwhile, our temperatures will be mild and close to average for mid May, but it is looking like a much wetter than average month area wide with mid month totals already there. /24/ LONG TERM.../Tuesday through Saturday Night/ A broad upper low will remain over Eastern Colorado until late Wednesday keeping southwesterly flow aloft in place and a rich plume of deep layer moisture streaming into the area. A stationary front will be located from Southern Arkansas westward along the Red River between Oklahoma and Texas to a surface low in Eastern New Mexico. Scattered to widespread showers and thunderstorms should be ongoing along the warm front and across East Texas. This activity will gradually spread eastward during the day across most of the forecast area. A complex of thunderstorms should slowly move into and across the region Tuesday night through Wednesday night as the upper trough begins to lift northeast into the Central Plains and the frontal boundary sags southward towards the Interstate 30 corridor before stalling once again. This will likely be the most likely time period for heavy rainfall and flash flooding. At this time, it is still a bit early for any flood headlines so will hold off for later forecast issuances. By Thursday morning, vertical ascent will decrease considerably across the region with the upper low far to the north. However, a cutoff shortwave trough in Central Texas will still supply sufficient lift for a broad area of scattered showers and thunderstorms in a warm air advection regime across the eastern half of Oklahoma and Texas. Rainfall amounts should be considerably lower with this activity compared to Tuesday-Wednesday. Rain chances will gradually decrease from east to west through Saturday as ridging aloft and at the surface over the Southeast CONUS begins to expand and retrograde west. After sunrise Thursday through Saturday night, convective coverage and intensity can generally be expected to be lowest during the overnight and early morning hours before peaking during the afternoon and evening. Little has changed regarding storm total rainfall amounts through Saturday afternoon. Rainfall totals may remain below 2 inches across our easternmost parishes of Louisiana, but totals will increase dramatically farther west. Amounts closer to 4 to 5 inches will be possible in Extreme East Texas, Southwest Arkansas south of Interstate 30, and Extreme Northwest and Western Louisiana. 6 to 8 inches, with isolated higher amounts, are possible east of a line from Lufkin TX to Nashville AR. /CN/ && .PRELIMINARY POINT TEMPS/POPS... SHV 67 81 69 83 / 70 80 40 80 MLU 67 81 67 84 / 50 70 40 50 DEQ 64 78 67 79 / 90 90 60 80 TXK 66 79 68 81 / 90 80 50 80 ELD 64 77 66 83 / 80 80 50 60 TYR 67 81 70 84 / 50 80 40 90 GGG 66 81 68 82 / 70 70 40 80 LFK 67 82 70 84 / 60 70 40 80 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 16/99
Area Forecast Discussion
National Weather Service Topeka KS
554 PM CDT Sun May 16 2021 ...AVIATION UPDATE... .DISCUSSION... Issued at 356 PM CDT Sun May 16 2021 Early this afternoon a mid-level perturbation was moving east across the state of KS. An outflow boundary was draped across the southwest counties and then extended east-southeast to EMP and then east-northeast along I-35. Ascent ahead of the perturbation combined with a weak cap and ascent along and north of the OFB was enough lift for showers and thunderstorms to redevelop this afternoon. Some of the storms that form along the outflow boundary have produced brief funnels as pre-existing vertical vorticity close to the surface along the boundary has been stretched vertically producing the funnel clouds. The stronger cells should diminish after sunset. Though we may keep scattered showers and a few elevated thunderstorms as weak isentropic lift develops north of the boundary. The thunderstorms that develop along the high plains this evening will probably weaken as they move into central KS. I cannot rule out some of the leftover showers moving across the CWA Monday morning. We may see a break in the rain Monday afternoon into Monday night. However, a southern stream upper level trough will be lifting northeast out of NM and across west TX on Tuesday. Rich gulf moisture will advecting northward at 850mb and the resulting anisotropic lift will cause rain and thunderstorms to redevelop Tuesday afternoon, with periods of showers and thunderstorms continuing into Thursday morning. Some of the rain may be heavy at times across eastern KS on Wednesday as the H5 trough lifts northeast across the state of KS. Thursday afternoon through Friday night, we may see another break in the rain and storms, though there could be isolated showers and storms due the continue rich gulf moisture advection across the Plains but a down stream upper ridge amplifying across the MS River Valley will provide for enough large scale subsidence. An amplified upper level trough will move east into the central Rookies. Saturday through Sunday, there may be a better chance for showers and thunderstorms across the CWA as the upper trough fills and lifts northeast across the northern high plains. The southwesterly mid level flow will be stronger across eastern CO and western KS, so I think our chances for severe thunderstorms across the CWA will be low. However, due to all the rainfall we may see some more flooding problems. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday) Issued at 554 PM CDT Sun May 16 2021 2230Z water vapor and profiler data suggests a shortwave trough axis is moving east towards the MO state line now. Except for some isolated activity across central KS, it looks like the back edge of the showers is working it`s way through the forecast area now. CAMs support the idea of precip ending this evening. Which brings the question of LIFR potential with CIGs and VSBY. Forecast soundings from the RAP and NAM show almost a completely saturated boundary layer. Winds look to favor LIFR conditions but the question is will high clouds clear out. Convection in the high plains of CO may cast additional cirrus over the area tonight. Think the probability for IFR is high enough to include in the forecast and will monitor trends before taking the forecast into LIFR. Forecast soundings show the boundary layer mixing out around 16Z Monday with CIGs improving through the afternoon. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Gargan AVIATION...Wolters