Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/27/22

Area Forecast Discussion
National Weather Service Denver/Boulder CO
859 PM MST Wed Jan 26 2022 .UPDATE... Issued at 858 PM MST Wed Jan 26 2022 Not the easiest forecast regarding snowfall and impacts for tomorrow. The short wave is dropping southward across Montana this evening, but also shearing to the southwest. We will have a decent batch of weak to moderate QG ascent coming toward us, and most of it should pass nearly overhead. Looking toward frontogenesis, there`s nothing terribly well defined yet, although there is definite mid level mass convergence over us by Thursday morning. Just those two factors alone should give us a nice mid level cloud deck which should start to precipitate, but very lightly, late tonight across the plains. Looks like most of this would be just east of I-25 in the wee morning hours. Then, winds begin to turn into the Front Range, and even moreso behind the cold frontal passage expected around 7-8 am. Snow is expected to fill in rather quickly across the Front Range I-25 Corridor and Foothills behind this frontal surge, thanks to the stronger upslope component and continued forcing. Lapse rates turn neutral, so the response should be pretty decent. We have increased the snow amounts just slightly, but they`re still shy of Winter Weather Advisory, with generally 1-4" amounts across the I-25 Corridor (heaviest south Denver Metro and near the foothills). Those types of amounts and sufficiently cold road temps would yield an Advisory if we were certain the snow would start during the rush hour, but there`s still considerable uncertainty here as to the exact timing. We`ll message the potential accordingly, and the second half of the commute could still get slow and hazardous. The NAMNEST was especially concerning (heavier and faster), and the EC also seemed a little faster with snow development. However, the trough is shearing and that`s what gives us pause as to exactly how fast the front and stronger upslope arrive. HRRR and RAP appear to be slowest, but they sometimes have a slight late bias. Other factors like dendritic growth look decent, a little deeper through the best vertical motion zone than Tuesday. However, moisture is less with PW closer to 0.2-0.25 inch, versus 0.30 inch Tuesday. && .SHORT TERM...(This evening through Thursday) Issued at 129 PM MST Wed Jan 26 2022 Very similar scenario through tomorrow as what we had on Tuesday, with northwest flow over the forecast area and a shortwave trough dropping down into the Four Corners area by mid day Thursday. At the surface, southerly drainage flow along the front range tonight will turn back northerly after sunrise Thursday as a cold front moves through the area. On the northeast plains northwesterly surface winds overnight will carry through the morning. This system will be a few hours later to evolve, with snow beginning around 6 am along the Wyoming border on the plains, and spread southward later that morning. Differences are slower timing, and lower potential for snow on the plains. QG fields show best ascent closer to the forecast area than with Tuesday`s trough, with center of max upward motion traversing the western portion Jackson/Grand/Summit/Park counties. In addition to the mid tropospheric ascent, in the lower levels frontogenesis associated with the cold front will provide upward motion below 600 mb. Best upward motion is in the mid levels associated with the upper trough, with the low level frontogenetical forcing a little weaker. The favored dendritic growth zone of -12 to -18C aligns with the higher RH, however overall moisture content in the atmosphere this time around is lower than previous. Precipitable forecast precipitable water Thursday is near 0.2 inch, compared with near 0.3 inch on Tuesday. Additionally, low levels of the atmosphere start out quite dry, and so several hours of alignment of ascent, RH, and -12-18c layer will be spent moistening the boundary layer to overcome evaporation/sublimation of the falling snow. Period of heaviest snowfall, roughly 1/2 inch per hour rates, 8 to 11 am on the northern plains, 10 am to 1 pm in the Denver metro, and mid day to early afternoon south along the Palmer divide. Forecast snowfall about 1/2 what we had Tuesday, with lower precipitable water yielding lower QPF and snow. 1-3 inches across the metro and I-25 south corridor, and 2-5 inches in the foothills where mid-level upslope flow will help give a boost to snow production. Given the light snowfall amounts and timing later in the morning outside the morning commute, will hold off on any headlines. In the mountains, chances for snow pick up overnight with the approaching upper low, and the higher elevations and passes gaining a couple inches. Temperatures...warmer tonight than last night as wind increases ahead of next approaching system to mix out the boundary layer and reduce radiational cooling. Colder daytime temperatures Thursday behind the front, near freezing along the I-25 corridor to upper 30s northeast plains, and teens to near 20 in the mountains. .LONG TERM...(Thursday night through Wednesday) Issued at 129 PM MST Wed Jan 26 2022 Latest storm system exiting Colorado Thursday night with clearing skies and cold temperatures. For Friday through much of the weekend, a high amplitude ridge of high pressure builds in across much of the west with a dry and warming trend. Temperatures will rise into the 40s on Friday, then a period of 50s for the weekend across the plains. 700mb temperatures will range from 0C-2C over the weekend which would support these warming temperatures. There is a weak upper low that moves across New Mexico on Sunday but this placement is too far south for any impacts for Northern Colorado. The next storm system to impact Colorado will be next Tuesday through early Wednesday time frame with colder temperatures and a chance of snow. Long range models trends line up a little better today as both the GFS/European solutions deepens the low into Utah on Tuesday before the GFS continues to deepen it into Arizona on Wednesday while European solution keeps the low a bit further north. Will maintain colder temperatures and increase snow chances a bit higher with today`s forecast but certainly solutions will see more changes before the event. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 459 PM MST Wed Jan 26 2022 Main concern will be development of lower ceilings and snow. Cloud decks will gradually lower overnight, but be of insignificance until closer 09Z-13Z when ceilings are expected to drop to around 5000-6000 feet with virga and a low chance of a light flurry developing. Cold front is expected to push through around 15Z with snow and IFR ceilings and visibility developing shortly thereafter. Main snow period is expected 16Z-20Z, with a brief period of moderate snow and VLIFR conditions in that window. Winds expected to gust to 15-20 knots from the north/northeast with the front, and then weaken through late afternoon. Conditions should gradually improve 20Z-22Z with snow moving out of the area and flight conditions improving to MVFR. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Barjenbruch SHORT TERM...Hanson LONG TERM...Entrekin AVIATION...Barjenbruch
Area Forecast Discussion
National Weather Service Grand Forks ND
1001 PM CST Wed Jan 26 2022 .UPDATE... Issued at 1001 PM CST Wed Jan 26 2022 Getting some reports of freezing drizzle in the Fargo area, so adjusted weather grids to include a mention. Winds have been less impressive than expected, with most of the restrictions of visibility with the falling snow in heavier snow showers. However, given the freezing drizzle and the likelihood of more blowing snow later tonight as the reinforcing cold front drops down, will leave headlines as they are for now. Strong cold air advection bringing colder temperatures, as well as the valley component to the winds should again bring some blowing snow into the Thursday morning commute. UPDATE Issued at 651 PM CST Wed Jan 26 2022 Adjusted POPs for snow showers continuing to move their way down the Red River Valley as the first cold front pushes down. Expanded POPs and broadbrushed them a bit more as there seems to be more snow activity further west and south than originally thought. Blowing snow decreases quickly as the falling snow ends thanks to fairly warm temps, but the main push of arctic air is still to come, so think vis will go back down later tonight into tomorrow morning. At this point will keep headlines going, emphasizing a lull in bad conditions this evening after the first front and before the second. && .SHORT TERM...(This evening through Thursday night) Issued at 300 PM CST Wed Jan 26 2022 The main forecast emphasis is on the near blizzard potential from gusty northwest to north winds and convective streamers (even snow squalls?) tonight into Thursday morning. Have issued a Winter Weather Advisory to cover these impacts, and will be monitoring through the night to see whether any additional updates are needed. As of 2 pm this afternoon, the warm front was pushing through portions of the Red River Valley. Grand Forks had warmed to 32 degrees, Langdon 30 degrees, and Jamestown 36 degrees, with the westerly wind push. This warm spell will be very short lived, as the next cold front is already poised along the Canadian border. This cold front will sweep southward into the northern FA by early evening. Wind speeds at Brandon and Winnipeg Manitoba were in the 33 to 37 knot range, with some blowing snow. Upstream Canadian radars were showing a steady band of snow just north of the International border. As this drops into the FA late this afternoon and evening (combined with the gusty northwest winds), near blizzard conditions are possible, especially in open country along and west of the Red River Valley. Other regional radars and satellite imagery were showing convective streamer clouds forming over north central North Dakota. This shows the potential for snow squalls as well, where visibilities can drop to zero over short distances. Last Friday was a somewhat similar set up, and Interstate 29 was closed from Grand Forks to the Canadian border. Since temperatures are quite warm initially, without falling snow, it will be hard to get really low visibilities. However, as mentioned above, there is some upstream falling snow. Moving a little later into tonight, a secondary cold front is expected to drop from the northern toward southern Red River Valley. This will bring a surge of 925mb cold advection, good pressure rises, and straight north winds. Since temperatures will be much colder by then, snow becomes easier to loft. The RAP show 925mb wind speeds at least 35 knots well into tonight and Thursday morning. Therefore, think lofted snow will combine with these winds to keep areas of low visibility throughout this time frame. Will use noon Thursday as an end time for now, later shifts can adjust as need be. .LONG TERM...(Friday through Wednesday) Issued at 300 PM CST Wed Jan 26 2022 A short period of quieter weather settles into the northern plains over the weekend, with the possibility of more snow heading into the start of next week. Synoptically, we will be under the influence of a ridge starting early next week, where our flow will turn westerly and temperatures will warm. After that period, more NW flow sets up and we return back to colder temperatures. Ending the week, we will see warming temperatures for a few days, thanks to southerly flow ahead of our next system. Saturday will see highs in the mid to upper 20s, and partly cloudy skies. Saturday afternoon into evening, our winds will shift to be out of the west and eventually the south for Sunday. This will allow warmer air to move into the area, making Monday an unseasonably "warm" day with temperatures hovering around freezing. There is the possibility in the ensembles for another system to move through as we transition back into NW flow towards the middle of next week, however, guidance remains murky. Confidence is low on timing, track, amounts, and effects we could see, but we will keep an eye on it as it gets closer temporally. Temperatures are expected to sink right back down mid-week, with Wednesday calling for single digit highs above and below zero right now. We could see some wind chill concerns heading into mid-week as well, so we will continue to monitor this as well. Enjoy the quieter weather while you can! && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 543 PM CST Wed Jan 26 2022 Band of snow showers moving into KGFK have brought vis down to 1/2SM, but should be pretty short lived, maybe gone even before 00Z. The snow showers as well as blowing snow will periodically reduce vis through this evening, but will be mostly in the 1 to 5 mile range. Will watch for some lower vis as the secondary cold front comes down later tonight into tomorrow morning, but not confident enough to include very low vis with blowing snow at this point. Ceilings will be bouncing between MVFR and VFR for the most part. Some improvement by the end of the period as winds and clouds decrease by Thursday afternoon. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Winter Weather Advisory until noon CST Thursday for NDZ006>008- 014>016-024-026>030-038-039-054. Winter Weather Advisory until noon CST Thursday for NDZ053. MN...Winter Weather Advisory until noon CST Thursday for MNZ001>005- 007-008-013>015. Winter Weather Advisory until noon CST Thursday for MNZ029. $$ UPDATE...JR SHORT TERM...Godon LONG TERM...AK AVIATION...JR
National Weather Service Morristown TN
919 PM EST Wed Jan 26 2022 .UPDATE... EVENING UPDATE. && .DISCUSSION... No significant changes for the evening update. Temperatures are perhaps a touch warmer than forecast, which is honestly a little perplexing given the calm winds, clear skies, and very dry air in place. The last several runs of the RAP and HRRR have trended warmer with temperatures tonight. Given hourly temperatures running warmer than previously expected, it seems hard to ignore this trend in rapidly updating CAM guidance so adjusted overnight lows upward just a touch. Still expect to see lows in the teens in southwest Virginia, along with portions of the northern plateau and in the TN valley near the VA border. Otherwise, no changes made to the forecast. CD && .AVIATION... 00Z TAF DISCUSSION. VFR conditions will prevail through the period, with only some high clouds passing through at times. High pressure shifts east of the Appalachians tonight so expect light NELY winds tonight to veer around to light SWLY by midday or so tomorrow. CD && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 25 52 35 43 19 / 0 0 0 20 0 Knoxville McGhee Tyson Airport, TN 21 48 32 40 15 / 0 0 0 50 20 Oak Ridge, TN 21 47 32 40 15 / 0 0 0 40 10 Tri Cities Airport, TN 17 45 29 38 14 / 0 0 0 70 50 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$
Area Forecast Discussion
National Weather Service Norman OK
455 PM CST Wed Jan 26 2022 ...New AVIATION... .SHORT TERM... (This evening through Thursday) Issued at 1219 PM CST Wed Jan 26 2022 The short term issue will be snow precipitation today during the afternoon through the evening hours. Energy from a shortwave trough over the Southern Rockies had been producing bands of snow this morning east of the troughs axis across the Texas Panhandle with some heavy amounts. Expecting the upper wave to continue digging across the Southern High Plains this afternoon with the snow moving into western and southwestern Oklahoma and western north Texas. Latest radar mosaic showing the first round of up to moderate intensity snow off the high plains starting to move into southwestern Oklahoma. Latest model runs have been increasing the total snow accumulations, with the HRRR & GFS a little more representative. Could expect to see accumulations from 1.5 up to 3.0 inches in our current advisory area of westcentral and southwest Oklahoma and portions of western north Texas. Travel along I-40 between Oklahoma City and the Texas Panhandle may be hampered by the snow and its reduced visibilities. Expecting this area of snow to begin moving into central Oklahoma toward early evening hours with lighter accumulations up to a half an inch. By late evening, most of our area should lie west of the trough axis with the mid-level ascent weakening and the snow concluding. Although will keep it out of the grids for now, forecast soundings suggesting dense fog possible early Thursday across portions of western Oklahoma. Did go slightly cooler than NBM with the CONSRAW Thursday afternoons MaxT due to a likely snowpack, especially across our west. && .LONG TERM... (Thursday night through next Tuesday) Issued at 254 PM CST Wed Jan 26 2022 Friday morning our area will be on the back side of a cold front as a dry upper trough moves through. However, will see the cold air quickly retreating back to the north as the Southern Plains will be on the eastern periphery of an upper ridge building across the western U.S. With ridging, we should see a warming trend through early next week with above seasonably average daytime temperatures. Models are consistent with a shortwave trough out in the Pacific coming ashore across the western U.S. and breaking down the ridge, eventually reaching the Southern Plains by Monday. Both GFS and ECMWF bring the upper low across northern Texas, although a slightly more northerly track taking it across Oklahoma using the Canadian NH model solution. With a return of south winds on Monday and increasing low-level flow and gulf moisture transport, cannot rule out POPs for rain across southeast Oklahoma during the afternoon. However will keep the rain POPs very low with better chances more east of our forecast area. It will be more windy on Tuesday as the surface isobars tighten and south winds increase. As a result, had to populate the afternoon wind grids using a more robust NBM 90th percentile. The bigger weather show may be more toward the middle of next week, generally late Tuesday into Wednesday as another but more deeper amplitude wave sets up across the western U.S. Weak shortwaves propagating through the trough may initiate rain Tuesday afternoon across eastcentral & southeast portions of Oklahoma, with POPs increasing further westward across our area as our next really strong cold front starts to push through. However, the models this far out are in disagreement temporally with the ECMWF & Canadian models pushing it through early Tuesday, yet much later with the GFS. The 1000-850 thickness fields are showing frigid Canadian based air behind this mid-week frontal boundary. Either way, could see a wintery mix of precipitation by Tuesday evening and overnight into Wednesday. && .AVIATION... (00Z TAFS) Issued at 450 PM CST Wed Jan 26 2022 Band of snow will move east across many of the TAF sites over the next 2 to 3 hours before shifting east. With the snow will come mainly MVFR ceilings and visibility but could see a brief period of IFR. Otherwise, expect to see a return of VFR conditions overnight with light south/southwest winds. There is a chance for some fog toward morning across parts of western into northern Oklahoma. Mainly some high clouds during the day Thursday with a weak surface boundary working south across the area which will shift the winds to the north during the latter part of the forecast. && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 24 44 24 48 / 40 0 0 0 Hobart OK 18 45 21 51 / 60 0 0 0 Wichita Falls TX 27 49 26 52 / 70 0 0 0 Gage OK 16 44 18 54 / 0 0 0 0 Ponca City OK 22 45 20 49 / 40 0 0 0 Durant OK 32 51 29 52 / 30 0 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...Winter Weather Advisory until midnight CST tonight for OKZ014>018-021>024-027-033>039-044. TX...Winter Weather Advisory until midnight CST tonight for TXZ083>086. && $$ SHORT TERM...68 LONG TERM....68 AVIATION...30
Area Forecast Discussion
National Weather Service Paducah KY
909 PM CST Wed Jan 26 2022 .UPDATE... Issued at 908 PM CST Wed Jan 26 2022 Some minor first (period) tweaks to reflect some temperature/dewpoint/wind adjustments with observations. Having the the WFO PAH forecast area being split by the high pressure axis from southwest to northeast at the surface makes temperature/dewpoint/wind forecasts tricky. Subtle micro-scale and topographical variability this evening will make hourly temperature adjustments a nightmare, until the mid-deck of cloud cover filters across the area overnight. Most of the moisture still appears to be confined in the 295-300 Kelvin Isentropic layer (with the leading edge 8-10kft agl) with sharp delineation between clear and overcast skies. Another issue is how much of the precipitation will actually reach the surface and provide any observable/impactful issue between midnight tonight and noon, especially across the northern third of the WFO PAH forecast area. Precipitation schemes from NSSL-WRFARW-4km, NAM 4km NAMest, High Resolution FV3 favor a more robust saturation/precipitation loading of the mid-cloud layer. Although reasonable, the precipitation loading from the aforementioned models may be somewhat overdone compared to observations. From surface and radar observations in Oklahoma early this evening, combined with differential water vapor imagery, suggest that significant forcing is need to generate sufficient snow production aloft to overcome drying further down the atmospheric column. Little in the way of significant wet-bulb adjustments are taking place except under the area of maximum lift. With this in mind, leaned closer to the Canadian, HRRR, RAP guidance for PoPs/QPF through 12z Thursday (6 am CST Thursday). All were similar in increasing any measurable snowfall footprint (albeit low, less than a tenth of an inch between the Perry MO/IL county areas after 3am Thursday). Between 2 am and 9 am Thursday appears to be about the best window for focused deformation and lift over the northern third of the WFO PAH for any noticeable snow production. At this point, the current forecast trends for snow flurries/isolated pockets of measurable snowfall look on target early Thursday. This should not create any hazardous weather impact for the WFO PAH forecast area overnight or early Thursday. && .SHORT TERM...(Tonight through Friday night) Issued at 103 PM CST Wed Jan 26 2022 High pressure over the area continued to result in mostly clear skies and cold conditions today. A shortwave over New Mexico is forecast to move toward the area tonight and weaken as it encounters decent confluence. This weakening and lack of overall moisture (most of which is aoa 700mb) means we will go with just a small chance of flurries, or slight chance PoPs for light snow from SEMO into southern IL and southwest IN late tonight into midday Thursday. Held on to some flurries over the KY Pennyrile region Thursday night for continuity. High temperatures will be 10 to 15 degrees higher Thursday vs. today. A longer wave trof will move across the area Friday. There could be a fair amount of clouds east of the MS River, and possibly flurries from SW IN into the KY Pennyrile region. Something to monitor for now. Otherwise another cold day, with mostly clear and cold conditions on tap for Friday night. .LONG TERM...(Saturday through Wednesday) Issued at 103 PM CST Wed Jan 26 2022 Saturday through Monday should be dry with milder temperatures. Other than a fropa without fanfare Sunday, return southerly flow and rising heights will promote the escape from the colder than average temperatures. The pattern becomes unsettled Tuesday through Wednesday. A trof is forecast to dig from the Pacific NW across the Four Corners, eventually ending up over the Plains by late Wednesday night. As is typically the case, the EC/CMC solutions are in respectable agreement with the GFS again an outlier. It develops a second lower out west, ejecting energy from the main trof toward the Great Lakes and much faster with the overall movement. Will discount the latest GFS and keep with NBM and the consensus model output including their ensemble mean solutions. Rain chances ramp up Tuesday and continue through Wednesday night. At this time, the Wed-Wed night time frame seems to be the focus. The pattern has that locally heavy rain possible look. Temperatures will be on the mild side through the period, for this time of year. && .AVIATION... Issued at 533 PM CST Wed Jan 26 2022 With the WFO PAH 00z Thursday WFO PAH TAF issuance, ceilings should remain VFR for the entire forecast period, as well as the surface visibilities. Kept the mention of vicinity (VC) showers (in this case, snow showers) during the period of highest probability of precipitation in each of the TAF locations. The majority of the precipitation will likely come out of 8-10kft AGL altostratus/cumulus deck arcing its way from the the western Gulf of Mexico through Texas, Oklahoma, Arkansas, and Missouri tonight into tomorrow. Condensation pressure deficits of 10-20 mb from the NAM-WRF FV3 High resolution guidance correspond well with the timing and location of the best precipitation chances. There may be some lowering of the cloud layer to lower VFR categories (4-8kft agl) near 12z- 15z Thursday, until warm air advection aloft takes effect. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...Smith AVIATION...Smith