Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/18/23


Area Forecast Discussion
National Weather Service Billings MT
143 PM MDT Fri Mar 17 2023 .DISCUSSION... Tonight through Saturday night... As of 1pm, there remains a band of light snow/flurries from Miles City to the southeast corner of MT. This is within an axis of weak 850mb frontogenesis, which is waning, thus the very light precip should finally taper off over the next couple hours. Surface analysis shows a 1034mb high over northeast MT and this will sag slowly to the south tonight. Light winds, clearing skies and some boundary layer moistening from snow melt could lead to localized fog especially east of Billings tonight...though this is of very low confidence at this time. The HRRR is suggestive of fog near Miles City tonight but shows much greater coverage over northeast MT. Something to keep an eye on. Otherwise, ridge building from the west will bring us quiet weather over the next 36 hours...along with a gradual warming trend after what will be a chilly night tonight. Lows tonight should fall below zero at Baker (it is only 13F currently), with single digits and teens elsewhere. No chance of any record lows though. Highs tomorrow should range from near 30F at Baker to the mid-upper 40s across our west. Saturday night will be milder, w/ a modest increase in downslope winds along our western foothills as a lee side trof develops. Strongest winds on Saturday itself should be in Carbon County per Bighorn Basin drainage (25-35 mph gusts). In all, we should finally be seeing more rapid lower elevation snow melt these next couple days. By the way, today is day #135 without reaching 57 degrees at the Billings airport. This has now eclipsed the old record by 7 days. JKL Sunday through Friday... Sunday will be mostly sunny with highs in the 40s to low 50s across the region, wrapping up a beautiful, and seasonal, weekend. A weak back door cold front will drop in from the northeast late Sunday bringing slightly cooler temperatures to the region to start the work week. Precipitation chances will then return for the mountains and lower elevations during the week as a trough moves inland over the west coast, providing energy and moisture across our region. Lots of uncertainty remains in how the trough will evolve as it moves inland though, which will impact how the precipitation sets up. Right now, it looks like snow will move into the mountains during the day Monday, before spreading across the lower elevations and plains Tuesday into Wednesday. The mountains have a 60% chance for 2 inches of snow. The lower elevations and plains will be more complicated as deep cold air is not expected with this event, so snow will be wet, lowering possible accumulations. After Wednesday, the coldest day of the week with highs potentially in the low to mid 30s, temperatures will increase into the 40s allowing scattered rain showers to mix in east of Billings. Since uncertainty remains in how the trough will form, a lot of uncertainty also remains in how quickly the trough and precipitation will move out Thursday into Friday. A slower trough will result in precipitation chances sticking around through the week, but a faster trough will allow for clearing by the end of week. Arends && .AVIATION... Band of light snow over KMLS to the southeast corner of MT (w/ MVFR-IFR conditions) will dissipate thru the remainder of this afternoon. Building high pressure will bring widespread VFR over the next 24 hours...though there is a slight risk of fog near KMLS & KBHK late tonight into early Saturday (from roughly 10-15z). NW winds gusting 15-25 knots east of KBIL will diminish quickly after 00z this evening. JKL && .PRELIMINARY POINT TEMP/POPS... Sat Sun Mon Tue Wed Thu Fri ----------------------------------------------------------- BIL 018/047 029/054 027/047 026/039 026/038 027/047 030/049 00/U 00/U 01/E 23/S 45/S 42/O 11/B LVM 012/046 026/049 029/046 028/041 026/040 028/044 028/043 00/U 00/N 02/O 33/S 45/S 43/S 22/S HDN 011/047 020/054 022/049 022/041 024/040 023/046 025/049 00/U 00/U 00/E 13/S 55/S 53/O 22/R MLS 005/038 019/044 019/039 022/038 025/036 024/037 023/043 00/U 00/B 00/E 02/S 45/S 53/S 11/B 4BQ 006/039 019/051 022/048 026/042 028/039 027/042 027/046 00/U 00/B 00/B 12/S 45/O 53/S 21/B BHK 906/030 013/040 013/031 014/031 018/033 020/034 017/038 00/U 00/B 00/E 12/S 46/S 54/S 21/B SHR 007/041 015/047 019/045 020/039 021/037 021/041 023/043 00/U 00/U 00/E 13/O 56/O 53/S 22/S && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings
Area Forecast Discussion
National Weather Service Columbia SC
753 PM EDT Fri Mar 17 2023 .SYNOPSIS... Cold front and shower activity will push through the forecast area tonight. Cool and very dry air returns for the weekend into early next week, including the potential for a frost or freeze. Air mass will moderate beginning Tuesday with above average temperatures by the end of the week. && .NEAR TERM /THROUGH TONIGHT/... Cold front and associated area of showers will move through the forecast area tonight. Limited instability so not expecting thunder. Precipitation is expected to move out of our FA by daybreak. Expect a wind shift to NW behind the front, with diminishing speeds, with drier low level air filtering in. Lows in the middle 40s north to low 50s south and east. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... The front will be slowly shifting off the coast early Saturday morning with lingering moisture gradient in place, although HREF indicates that PWATs will be less than an inch across most of the area except for possibly the far southeastern forecast area. Pops continue to decrease through the morning as drier air will continue to push into the forecast area, especially in the low levels. Cooler with lower 500mb heights although cold advection likely won`t begin in earnest until Saturday night. Highs will be in the upper 50s to low 60s. HiRes models indicate the potential for some light rain in the southeastern forecast area Saturday evening into Saturday night as a shortwave moves through but soundings indicate a significant dry layer in the low levels so kept the forecast dry. Temperatures dropping into the 30s overnight Saturday, although blended guidance shows the highest probability for freeze remains in the Upstate of SC so have no freeze watch for early Sunday morning at this point. Cooler Sunday with 850mb temps below 0C as highs will struggle to rise, in the low to mid 50s even with only a few passing high clouds over the area. Higher chance for a freeze Sunday night into Monday morning across much of the area as the surface high will be centered just NW of the forecast area with better radiational cooling conditions. && .LONG TERM /MONDAY THROUGH FRIDAY/... Colder than average temperatures continue for Monday as blended guidance indicates highest probability for a freeze once again in the northern half of the forecast area. Ridging will begin to build over the area Tuesday as GEFS mean has been trending stronger with upper ridging. The NAEFS mean similarly indicates 500mb heights will exceed the 90th percentile leading to further confidence in temperatures well above average by the end of the week. EC and GEFS members continue to support a dry airmass in place through at least Wednesday with high probability of PWATs remaining below an inch. A bit more uncertainty late in the period as to the degree of moisture but with ensemble generally supporting rising heights through Thursday, kept the forecast dry through at least Thursday with a bit more uncertainty for Friday. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... MVFR Ceilings and visibilities arriving at all terminals associated with rainshowers and an arriving cold front. Improvement expected towards Saturday morning. METARs, radar and satellite indicating a fairly wide frontal band of weather moving into the region at 00Z, arriving at KAGS and KDNL now, then KCAE/KCUB and KOGB by 02-03Z. Upstream observations in GA show isolated IFR in heavier showers, but predominately widespread MVFR. Models are mixed on ceiling heights, with latest HRRR guidance indicating IFR overnight, but it is the outlier. Moderately confident primary impacts will be MVFR and am watching closely through the next 9-10 hours. Band of active weather associated with the front expected to push southward through our terminals by 09-11Z, but as frontal band stalls along the Coastal Plain impacts may linger slightly longer. High pressure and drier air pushes in after 16-19Z, expect improvement to VFR after sunrise as the day progresses. EXTENDED AVIATION OUTLOOK...No aviation impacts expected Sunday through Tuesday. Morning visibility impacts possible on Wednesday. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$
Area Forecast Discussion
National Weather Service Dodge City KS
420 PM CDT Fri Mar 17 2023 ...Updated Aviation... .SHORT TERM...(This evening through Saturday night) Issued at 1223 PM CDT Fri Mar 17 2023 Water vapor satellite imagery and RAP upper air analysis at midday depict a powerful upper level cut-off low centered over the far northern Midwest, resulting in longwave troughing over the majority of the CONUS. At the surface, gusty north-northwest winds will continue across the area through the afternoon today as high pressure builds into the central plains in the wake of yesterday`s cold front. However, the strong mid-March sun combined with the weakly downsloping winds will help to offset the effects of the cold front as temperatures peak in the upper 40s to low 50s this afternoon. Overnight tonight, vorticity maxima rotating around the upper level cut-off low will send another, albeit weaker cold front through southwest KS, giving our area another shot of cold air and supporting lows dropping into the teens to low 20s by sunrise. Daytime Saturday, gusty north-northwest winds will continue on the southern periphery of a ~1038-mb surface ridge centered over the northern plains. Despite the strong sun and weak downsloping winds, the reinforced cold airmass over the central plains will limit afternoon highs to the upper 30s to mid 40s. .LONG TERM...(Sunday through Friday) Issued at 217 PM CDT Fri Mar 17 2023 Medium range guidance is in agreement regarding the upper level pattern at the beginning of the long term period, suggesting an upper level ridge will build into the Intermountain West in the wake of the strong cut-off low that will be moving into the northeast CONUS/southeast Canada. In response, surface ridging will advance into the southern plains/western Dixie Alley region, resulting in southerly winds resuming across southwest KS and initiating a warming trend. 850-mb temperatures warming into the 2-9C range will translate to afternoon highs in the low 50s near central KS to the mid/upper 50s near the KS/CO border. Upper level ridging will eject into the High Plains and dampen during the day Monday ahead of the next upper level trough moving ashore over California. The surface pressure field consisting of high pressure over Dixie Alley and lee troughing across eastern CO/WY will result in increasing S/SSW winds throughout the central plains, supporting the continuation of the warming trend with afternoon highs in the low to mid 60s. Early Tuesday, a passing upper level shortwave trough will bring an outside chance of precipitation for the eastern zones, however ensemble means indicate the majority of the precipitation will fall over central and eastern KS as per usual, with only a hundredth or two within our CWA. Otherwise, the aforementioned upper level trough will take its time moving eastward, leaving southwest KS in roughly the same pattern as temperatures continue to rise into the upper 60s/low 70s Tuesday, and the upper 70s/low 80s Wednesday. On Thursday, latest runs of the EPS/GEFS predict the upper level trough will finally make significant progress eastward. Ensemble meteograms show some slight signal of precipitation chances with this feature and the associated cold frontal passage sometime Thursday, however confidence is very low at the moment. Regardless, cold advection behind the front will knock temperatures back down into the 50s and 60s by the end of the period. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 420 PM CDT Fri Mar 17 2023 Excellent flying weather is expected through this TAF cycle. Stratocumulus field currently will dissipate quickly at sunset. VFR/SKC is expected tonight through Saturday. Elevated gusty NW winds currently will diminish rapidly around sunset, with light northwest winds < 10 kts prevailing through 15z Sat. After 15z Sat, NW winds will increase once again, with modest gusts of 23-25 kts. && .PRELIMINARY POINT TEMPS/POPS... DDC 17 43 12 51 / 0 0 0 0 GCK 17 43 13 53 / 0 0 0 0 EHA 19 45 16 55 / 0 0 0 0 LBL 17 46 14 55 / 0 0 0 0 HYS 16 38 10 50 / 0 0 0 0 P28 21 44 15 50 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Springer LONG TERM...Springer AVIATION...Turner
Area Forecast Discussion
National Weather Service Duluth MN
1021 PM CDT Fri Mar 17 2023 .UPDATE... Issued at 1019 PM CDT Fri Mar 17 2023 Extended the Winter Weather Advisory across the MN Arrowhead overnight due to lower visibilities in blowing snow as seen on area webcams and observed at automated weather stations. Winds should pick up a little overnight adding to the visibility restrictions caused by blowing snow. && .DISCUSSION...(This evening through Thursday) Issued at 315 PM CDT Fri Mar 17 2023 Summary: Light to moderate snow continued this afternoon but will diminish for most later tonight except along the South Shore where heavy lake effect snow will occur. High pressure builds in later Saturday and will cause drying into Sunday. There will be a couple more opportunities for snow or a mix from mid to late week. Light to moderate snow continued over much of the Northland this afternoon with an area of heavier snow showers from the Bayfield Peninsula west-northwest into the Iron Range. These were occurring in an area of steeper low level lapse rates and some low level FGEN forcing. The steeper lapse rates/FGEN will continue and move south into this evening. Although not likely, a few snow squalls will be possible into this evening with brief visibility reductions to a quarter mile possible. Most of the snow will diminish or end later tonight except along portions of the South Shore, more on this below. Additional snowfall outside of far northern Wisconsin will range from a dusting to 2 inches with 2 to 5 inches from the Iron Range into the Arrowhead. We extended the Winter Weather Advisory for the Arrowhead to 5 AM Saturday. As far as far northern Wisconsin and particularly the South Shore, low level winds have backed to more west to northwest today but will veer to northerly tonight. Conditions for significant lake effect snow will become very favorable overnight with a long fetch, very favorable delta-T values, and rising inversion heights. We increased snow amounts some tonight from east-central Ashland County into northern Iron County. Snowfall rates will approach an inch per hour in the snowbelt. A bit further west, a gravity wave may again form tonight as depicted by the higher resolution models. The RAP does show drier air moving in though so that may offset the expected lift some. We forecast another 6 to 13 inches of snow in the snow belt of Ashland/Iron Counties tonight with 3 to 7 inches from east-central Douglas County into the Bayfield Peninsula. The Winter Storm Warnings from Douglas/Bayfield County were extended to 7 AM Saturday and to 1 PM Saturday for Ashland/Iron Counties. Drier air and backing low level winds should shut off the snow Saturday afternoon or evening. Dry conditions are then expected Sunday and Monday with warmer temperatures moving in. Highs Saturday in the lower to middle twenties will warm into the thirties Sunday and Monday. Another low pressure system will bring chances for snow or a rain/snow mix to the region mid-week. A few inches of snow will be possible mid-week. Yet another stronger area of low pressure may bring significant snow to the region late week. Take a deep breath...there is still quite a bit of uncertainty regarding the late week system. The models are showing plenty of differences in the track and the ECMWF ensemble members show very little clustering. It`s much to early to speculate on snow amounts with the late week system. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 644 PM CDT Fri Mar 17 2023 Remnants of the departing system linger with wrap around flow bringing IFR conditions and squally snow showers temporarily have lowered flight cats to VLIFR. These should taper down as the evening wears on and forcing exits. Until then, plenty of IFR in snow showers. Gusty winds overnight will also cause visibility reductions in BLSN. Eventually an improvement to VFR Saturday. && .MARINE... Issued at 315 PM CDT Fri Mar 17 2023 Northwest winds this afternoon will veer to north tonight and increase building waves further, mainly along the South Shore. Gales around 35 knots will be possible, both along parts of North Shore and around the Outer Apostle Islands. The wind will decrease a bit through the day Saturday and back to northwest late in the day then to west Saturday night. Winds will increase again Sunday. Conditions will remain hazardous through the weekend and Small Craft Advisories will likely be needed into early next week. The cold temperatures and waves will create areas of heavy freezing spray tonight into Saturday along the South Shore. Low visibility will also be likely into Saturday morning in snow showers. && .PRELIMINARY POINT TEMPS/POPS... DLH 7 23 7 34 / 60 10 0 0 INL 6 25 5 35 / 60 0 0 0 BRD 8 24 3 33 / 60 10 0 0 HYR 8 25 6 35 / 80 30 0 0 ASX 11 25 10 37 / 90 60 0 0 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...Winter Storm Warning until 7 AM CDT Saturday for WIZ001-002. Winter Storm Warning until 1 PM CDT Saturday for WIZ003-004. MN...Winter Weather Advisory until 5 AM CDT Saturday for MNZ011-012- 019>021. LS...Gale Warning until 4 AM CDT Sunday for LSZ140-141. Small Craft Advisory until 10 PM CDT Sunday for LSZ142>148. Heavy Freezing Spray Warning until 10 AM CDT Saturday for LSZ145. Heavy Freezing Spray Warning until 4 PM CDT Saturday for LSZ146>148-150. Gale Warning until 4 PM CDT Saturday for LSZ150. && $$ UPDATE...Wolfe DISCUSSION...Melde AVIATION...Wolfe MARINE...Melde
Area Forecast Discussion
National Weather Service Quad Cities IA IL
633 PM CDT Fri Mar 17 2023 ...00Z AVIATION UPDATE... .SYNOPSIS... Issued at 158 PM CDT Fri Mar 17 2023 An upper level low is evident on water vapor sinking southward across the Dakotas and Minnesota. Closer to home, yesterdays frontal boundary sits to our south and east with clear skies across the area. Gusty northwest winds of 15 to 25 MPH and gusts up to 35 MPH continue. Temperatures at 1 PM range from 22 degrees at Cedar Rapids to 32 degrees at Macomb and Keokuk. && .SHORT TERM...(This evening through Saturday) Issued at 158 PM CDT Fri Mar 17 2023 Key Messages: 1. Flurries possible tonight and Saturday. 2. Continued cold and windy through Saturday. Discussion: The main forecast concerns were winds and chances of precipitation. Models differ slightly in the placement of different features. A southeastward digging trough and closed 500 MB low will be the main driver for the weather this weekend. Two disturbances rotating through the trough will bring rounds of flurries to the area late this afternoon into tonight and again on Saturday afternoon. Subtle surface troughs will also accompany each shortwave. Model time series and soundings do not show very good saturation but there is enough for ice crystals and thus flurries as the energy moves across the area. The HRRR and RAP do show some 0 to 3 km CAPE up to 30 J/KG during these periods so there may be bursts of flurries instead of widespread flurries both tonight and Saturday. We are not expecting any accumulation from these shortwaves. Models do differ on the placement of QPF with the ECWMF and GFS being far to the east than other models. Low level dry air may work to limit the overall potential. The tight pressure gradient will remain across the area as high pressure remains to our northwest through the period. There will be some relaxing of the gradient on Saturday, but winds will remain breezy at 15 to 25 MPH. Temperatures will remain well below normal this weekend with low temperatures on Saturday morning ranging from 10 to 15 degrees. When factoring in the wind speed, wind chills on Saturday morning will be in the single digits below zero. Saturday`s high temperatures will be in the mid to upper 20s with the wind making it feel like it is 5 to 15 degrees above zero. .LONG TERM...(Saturday night through Friday) Issued at 158 PM CDT Fri Mar 17 2023 Key Messages... 1) A chilly night is expected Saturday night before gradually warming temperatures develop through Thursday 2) After an expected dry period, chances of precipitation return by mid-week, with perhaps some strong storms possible The long-term forecast period starts off with a chilly night Saturday night, with overnight lows in the lower to middle teens, and wind chills falling to the single digits - above and below zero. This will be due to a cold-core upper-level low that is progged to be located over far eastern Ontario Canada Saturday night. Our region continues to be under the cold air advection/cyclonic flow portion of the low, resulting in the colder conditions. Northwest winds will continue to be gusty Saturday evening, with gusts between 25 to 35 mph before slowly tapering off into Sunday morning. A pattern change is expected Sunday, as high pressure builds in from the northwest. The high pressure system will remain in control at least through the day Monday, with dry conditions. Winds will gradually turn more southerly Sunday, supporting warm air advection. High temperatures on Sunday will warm to the upper 30s, which is still below seasonal average, but will be welcomed warmth compared to the conditions for tonight and Saturday. Conditions become more active by mid-week, with a push of moisture off the Gulf of Mexico per wind streamlines. The global models and NBM suggest chances of rain to increase Tuesday night, ahead of a 35 to 45 knot low-level jet. Instability appears to be lacking, so only some light rain showers are expected for Tuesday night into Wednesday. Things might be more active on Thursday, as both the GFS and ECMWF deterministic and ensembles suggest a sharp baroclinic zone setting up somewhere along and southeast of our region. Instability appears to increase during this time, with the GEFS ensemble plumes suggesting SBCAPE values on the order of 200 to 700 J/kg across our south, although the ECMWF ensembles aren`t as bullish on instability. There should be plenty of moisture to work with along the boundary, with both the GEFS and ECMWF ensembles suggesting Pwat values 150 to 200% of average (average value for DVN being 0.42"). The ECMWF EFI for CAPE-Shear indicates a lower-end potential for strong to severe storms in our forecast area, with values around 0.5 to 0.7 for Thursday. The Storm Prediction Center has mentioned a potential for strong to severe storms in our region Thursday, but uncertainty remains regarding the ejection of the upper-level trough, and placement of related surface features. Definitely something to keep an eye on as we approach mid-week. Temperatures will gradually warm up into Thursday, with highs warming into the upper 50s and some 60s! && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 631 PM CDT Fri Mar 17 2023 Gusty NW winds 15-30 kts and bouts of VFR to MVFR stratus and flurries expected during the period. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...Cousins SHORT TERM...Cousins LONG TERM...Schultz AVIATION...McClure
Area Forecast Discussion
National Weather Service Lincoln IL
907 PM CDT Fri Mar 17 2023 .SYNOPSIS... Issued at 241 PM CDT Fri Mar 17 2023 Cooler than normal weather sticks around through the weekend, with wind chills overnight expected to be near or below zero north of I-72 with values in the single digits south of there. A weather system will bring scattered snow showers or flurries late tonight into Saturday. Temperatures look to rebound back to near normal values by early next week, with above normal temperatures returning by the middle of next week. && .UPDATE... Issued at 907 PM CDT Fri Mar 17 2023 After coordinating with neighboring office, snow chances have been increased further for tonight with potential for some light accumulations around a half inch or so north of I-74. Upstream observations show numerous snow showers advancing across central Iowa, with the leading edge now about to cross the southeast Iowa border with Illinois. RAP snow squall parameter is focusing on a period between about 11 pm and 4 am as steep low level lapse rates slide just south of the I-74 corridor. Winds will be increasing again after midnight and some low visibility will accompany the stronger showers. UPDATE Issued at 740 PM CDT Fri Mar 17 2023 Evening water vapor imagery continues to show an upper wave swinging across Iowa. Regional radar mosaics show numerous snow showers ahead of this wave, with the latest HRRR showing these reaching west central Illinois toward 9-10 pm. Additional snow showers should increase through midnight and focus on the east half of the forecast area through about 4-5 am. With another upper lobe swinging through the region on Saturday, along with steep low level lapse rates, additional flurries and snow showers are likely. Snow trends have been updated through Saturday to increase PoP`s some, generally to about 30% tonight and also increasing them Saturday afternoon to around 20%. Temperature and winds largely look on track. && .SHORT TERM...(This evening through Saturday night) ISSUED AT 241 PM CDT Fri Mar 17 2023 Clearing has just about made its way to the IL/IN state line just after 2 pm as surface ridging continues to nose further eastward. The sunshine sure is deceiving though as temperatures this afternoon are sitting in the 30s, which is 10-15 degrees below normal for mid March. This paired with a stiff northwest winds is making it feel even colder with wind chill readings in the 20s this afternoon. A 500 mb upper trough will swing through the Great Lakes Region later today, pushing a lobe of vorticity through central IL tonight. Clouds will increase with the wave, with forecast soundings showing just enough moisture and lift to support a few flurries or light snow showers overnight tonight, with on/off chances continuing through the daytime hours of Saturday as cyclonic flow remains positioned overhead. Although overall moisture will be starved with this system, there may be just enough to squeeze out a quick dusting of snow in some spots. Overnight lows tonight will be unseasonably cold with lows dipping down into the teens to low 20s. With winds remaining breezy overnight, wind chills will make it feel even colder with values expected to be near/below zero north of I-72. Values south of there will be in the single digits. Similar lows will be seen on Saturday night into Sunday morning, but decreasing winds will keep wind chills in the single digits to teens. && .LONG TERM...(Sunday through Friday) ISSUED AT 241 PM CDT Fri Mar 17 2023 Surface ridging slides into the area on Sunday, though temperatures will still be cold to close out the weekend. Southerly return flow sets up going into the start of the new week, with seasonable temperatures returning for Monday. Temperatures will continue to climb through the week, possibly peaking in the 60s or near 70 by Thursday. A couple of upper shortwaves look to bring precipitation back into the area by the middle of the week, with a stronger system/upper wave progged to move through Thursday into Friday. Sufficient moisture looks to advect back northward ahead of the late week system, which should be enough to support storms, possibly severe. It is still a little early to discern the details of this system, but something to keep our eyes on. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 617 PM CDT Fri Mar 17 2023 Main aviation the next 24 hours will remain with the winds, as west/northwest winds will continue to gust 25 to 35 knots much of the time. There will be a period this evening where the winds drop off, but then pick up again 06-08Z as a cold front swings through the area. This front will also bring ceilings getting close to 3,000 feet, though HREF ensembles suggest that KSPI/KDEC will have the best shot of dipping into MVFR territory for a time. Snow showers with the front have the potential for some brief visibility dips, but not enough to warrant a mention in the TAF`s at this point. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Geelhart SYNOPSIS...NMA SHORT TERM...NMA LONG TERM...NMA AVIATION...Geelhart
Area Forecast Discussion...UPDATED
National Weather Service Indianapolis IN
953 PM EDT Fri Mar 17 2023 .Forecast Update... Issued at 953 PM EDT Fri Mar 17 2023 The near-term forecast is in good shape with minimal adjustments needed. Satellite shows a general decrease in stratus across the area this evening. MSLP gradient is tight enough for winds to only decrease some tonight as mixing lessens. It is worth noting that cold advection and winds will be sufficient for single-digit wind chill values across roughly the northern two-thirds of the area tonight, with some near-zero values possible. Embedded within an eastward migrating deepening midlevel low is a fairly pronounced vort max progressing toward our area. Water vapor channel imagery shows this feature over Iowa now, and short term models show associated fairly strong DCVA moving into central Indiana during the predawn hours and progressing eastward through early morning. Upstream observations over Iowa show both pre- and post-frontal snow showers, and as the vorticity lobe sharpens/strengthens some overnight, the preceding snow band may organize further. Although forcing may not result in a classic snow squall scenario, steepening low-level lapse rates and small (but vertically confined) positive area (i.e., up to around 50 J/kg MLCAPE) evolve during the early morning hours, and drive snow squall parameter up to nonzero values. Current thinking is that brief visibility reduction in moderate to heavy snow along the DCVA forcing and surface frontal reflection should progress across central Indiana roughly in the 5:00am to 10:00am window. Its progressive/quick-moving nature should limit accumulation potential but up to one half inch may occur, especially north of roughly I-70. Steep low-level lapse rates persist into the afternoon and with even minimal surface warming/destabilization, renewed development of more PBL flow-parallel bands of snow showers may occur. A few hi-res models (i.e., HRRR are most aggressive) while others, including global models are more subdued, likely owing to differences in residual PBL moisture. We expect the most prevalent snow shower coverage during the afternoon diurnal convective cycle to be downwind of Lake Michigan north of our service area. However, at least enough convective instability within a vertically confined layer below a particularly low tropopause, and optimal placement within the dendritic temperature range should result in at least periodic flurries for most of our area. A reasonable worst case scenario would be heavy enough bursts of snow from snow showers to add a few tenths of an inch of snow accumulation, particularly across roughly the northern half of the area. The overnight shift will look closer at the afternoon potential and refine the forecast accordingly. && .Short Term...(This evening through Saturday) Issued at 259 PM EDT Fri Mar 17 2023 Main impacts through Tomorrow: - Cloud coverage and winds lessen overnight - Secondary arctic cold front approaches tomorrow morning - Isolated snow showers and scattered flurries for Saturday - Gusty winds and cloud coverage increase as well Rest of Today and Tonight: With the cold front well past the forecast area, current satellite imagery and METARs across Eastern Illinois and Western Indiana have captured the gradual weaning of the cloud deck that is anticipated through the overnight hours. Winds have correspondingly shifted to more westerly and northwesterly components across the forecast area, helping to advect drier air in at the surface. This corresponds to the dry slot of the parent low attached to this morning`s cold front, which will bring an end to PoPs this evening and a minor rebound in temperatures in the early portions of the evening. This advection of dry air at the surface will further promote the lifting of today`s persistent cloud shield overnight. After sunset, temperatures really begin to plummet and winds begin to drop in speeds. Due to the upper trough ejecting eastward into the Ohio Valley, expect the pressure to reduce overnight and allow for winds to weaken. Gusts in the 15-20 mph range may persist overnight, but conditions will not be as windy as they have been for the past 36 hours. Low temperatures will drop to below 20 in areas north of I-70 overnight, with the Indianapolis metropolitan area averaging around 22 and the southern tier counties closer to 25. Tomorrow: A well-defined arctic backdoor cold front is anticipated in the forecast area Saturday morning, bringing brisk air and a return to gusty winds/increased cloud coverage with it. Higher- resolution guidance continues to depict the development of a few snow showers. A deepening and broadening upper level low displaced to the north of the forecast area in the Great Lakes region will advect positive vorticity into the area, and modeled BUFKIT soundings portray lift in the areas immediately ahead of the front. However, the very dry air that advected in behind Friday`s initial cold front should limit the amount of snowflakes that reach the ground. Moisture levels remain the primary limiting factor in the set up for this particular event. Accumulations, if any, should not exceed more than a dusFlurries to some lgt snow possible overnight ting, but localized higher amounts are possible if the potential for enhanced low-level instability is realized. Therefore, the forecast will stick with isolated snow shower verbiage, with the potential for scattered low-impact flurries across the majority of the area noted. Temperature across the area will be limited by both the return of more widespread cloud coverage and the advection of a continental polar airmass into the area by increasing northwesterly winds in the wake of this secondary FROPA. While mixing from aloft will not be as pertinent as in past days this week, gusts may rise to 30 mph at the surface by tomorrow afternoon. Maximum temperatures tomorrow will struggle to rise above freezing, and wind chills will be quite potent heading into the overnight hours on Saturday. && .Long Term...(Saturday night through Friday) Issued at 259 PM EDT Fri Mar 17 2023 * Well-below normal temperatures through Sunday night * Warming trend beginning Monday * Rain likely by mid to late next week Saturday night through Sunday night... Some isolated flurries cannot be ruled out early Saturday evening with lingering low-level moisture, but confidence is low as upper ridging and surface high pressure begin to build in. Low clouds will initially limit diurnal cooling. However, well below normal temperatures are still expected with cold air advection and clearing skies later in the night. Look for lows in the upper teens across most areas and wind chills around 5-10F. Temperatures will warm into the mid 30s under mainly sunny skies on Sunday. Some diurnal cumulus/stratocu is expected as forecast soundings show lingering low-level moisture. Clear skies should allow for efficient diurnal cooling Sunday night, but winds will become southwesterly late as surface high pressure begins to move east. This may limit cooling slightly with temperatures in the low 20s. Next Week... Return flow around the back side of the surface high will lead to a significant shift in the weather pattern with temperatures warming up quickly. This warming trend will be aided by increasing heights aloft and strengthening south/southwesterly flow ahead of an approaching system Wednesday into Thursday. Precip chances return on Wednesday, associated with strong warm advective isentropic ascent. Although QPF amounts will likely be light on Wednesday due to a lack of upper level support. Heavier precipitation is expected late next week as guidance is in decent agreement that a low pressure system will move through the region. It is too early to determine rainfall amounts, but favorable dynamics combined with above normal PWAT anomalies should bring widespread rain to central Indiana. Precip chances persist through the end of the period as this system`s cold front likely sweeps across central IN late in the week. && .Aviation...(00Z TAF Issuance) Issued at 700 PM EDT Fri Mar 17 2023 Impacts: * A return to VFR is expected early this evening based on satellite/ob trends * Winds will lessen overnight but increase again with the front in the predawn hours * Low probability of snow showers Saturday morning Discussion: Dry advection is eroding the stratus deck, though enough low-level moisture remains in place that an upstream vort max will probably result in stratus on the margins of MVFR/VFR in the predawn hours. Enough ascent may be present for some flurries or light snow showers. The probability of significant visibility reductions appears low at this time given expected intensity, though we will need to monitor trends. Post-frontal environment and mixing will cause winds to increase again and veer slightly to west-northwesterly. They will remain gusty through the diurnal mixing period. Stratus will likely fill back in but should remain just above VFR thresholds, with ceiling restrictions being unlikely, but possible in a reasonable worst case scenario. Accompanying this stratus could be some flurries or snow showers through the afternoon, though this is conditional on sufficient low-level moisture, which models are currently giving mixed signals on. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ Update...BRB Short Term...Marcus/KH Long Term...Melo Aviation...BRB
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
847 PM CDT Fri Mar 17 2023 .UPDATE... Issued at 847 PM CDT Fri Mar 17 2023 Quick update this evening to greatly boost snow chances, particularly south of I-80 later this evening and overnight with increasing concern for more significant coverage of strong/gusty snow showers/squalls. Moisture channel loops depict a robust shortwave trough axis making quick progress across Iowa late this evening. At the base of this trough, intense DCVA is ongoing across parts of central and southeast Iowa where a gradual increase in coverage of snow/snow showers has been noted over the last 1-2 hours. While the 00z DVN RAOB sampled quite a bit of dry air, guidance continues to indicate a more substantial reservoir of low-level moisture exists to the south and at the leading edge of more intense height falls. RAP forecast soundings indicate surface to 750 mb lapse rates will continue to steepen incrementally over the next few hours along with sufficient saturation through a roughly 3-4 kft layer to support decent coverage of convective snow showers. Greatest coverage looks to exist south of I-80, and particularly along/south of the Kankakee River and peaking in the midnight to 5 AM timeframe. With boundary layer flow still fairly robust, the potential exists for brief wind gusts perhaps in excess of 40 mph within any more robust cores which may also facilitate brief visibility drops under a half mile. With temperatures in the 20s and falling, any more intense bursts will readily accumulate on roadways leading to a potential for slick and hazardous travel. Will also work to message this threat a bit more heavily in our graphical suite. Carlaw && .SHORT TERM... Issued at 300 PM CDT Fri Mar 17 2023 Through Saturday night... The key messages for the short term period: * Continued blustery conditions and turning much colder tonight, with wind chills down into the single digits to below zero by daybreak Saturday. * Quick hit of accumulating snow showers (generally under an inch) tonight south of the Kankakee River. * Occasional flurries likely for most areas on Saturday, with some lake enhanced snow showers possible Saturday afternoon and evening over northern Porter County IN. Water vapor imagery early this afternoon depicts the next upper level PV anomaly now shifting south-southeastward across the eastern Dakotas. This feature is expected to dig southeastward through the larger scale upper trough into southern WI and northern IL tonight. As it does so, it will drive an impressively cold arctic airmass, more reminiscent of January, into the area late tonight and on Saturday. While conditions will continue to be blustery and chilly this afternoon, temperatures will only get colder tonight as the aforementioned shot of cold arctic air sweeps into the area. Current air temperatures upstream of the area are hovering in the single digits to low teens above zero across a good chuck of Upper Midwest, and this same airmass is headed our way tonight. Locally, this airmass should result in low to mid teen surface temperatures by early Saturday morning, but continued blustery northwest winds will make it feel more like zero into daybreak Saturday! Thereafter, continued blustery conditions during the day will only allow temperatures to warm into the mid to upper 20s, a good 20 degrees below normal. One last very cold night will follow Saturday night before things begin to warm up later in the weekend. Expect temperatures Saturday night to once again drop back into the teens for overnight lows. While the unseasonably cold conditions tonight and on Saturday will be the primary weather story, there is also a good chance for a period of snow showers with the approaching PV anomaly tonight, particularly for areas south of the Kankakee River including central parts of IL into IN. Steep low-level lapse rates and somewhat better lower-level moisture in this area may even support a period of more vigorous snow showers, and potentially some snow accumulations under an inch. Elsewhere, we should see a good deal of strato cu developing under this cold upper trough tonight and on Saturday, and with this cloud layer looking to reside right in the DGZ, occasional flurries can be expected. Lake effect snow is also expected to kick up over and downstream of Lake Michigan on Saturday. While some of this could impact parts of northern Porter County with some minor accumulations under an inch, it appears the primary focus will remain east of the area. KJB && .LONG TERM... Issued at 323 PM CDT Fri Mar 17 2023 Sunday through Friday... After an unseasonably cold Saturday, temperatures will be on the mend through the first half of next week beginning on Sunday. However, we will remain on the cooler side of average to wrap up the weekend. Height rises behind the trough axis progged to swing through Saturday afternoon will promote WAA aloft and allow highs to reach the middle and upper 30s on Sunday. An awfully dry profile with synoptic-scale subsidence at play should allow for lots of sunshine throughout the day. A few more clouds should roll in on Monday with some mid level moisture flooding in on the backside of a high departing to our southeast. At the surface, breezy return flow will help pull highs on Monday back into the middle and upper 40s, right on par with climatological norms. The breeziness stems from a tight pressure gradient on the backside of the high and a notable LLJ moving overhead. Steep lapse rates through the lowest 100mb or so could allow us to mix down some 30-40 kt gusts through the afternoon. The continued warm advection looks to bring 50s area-wide on Tuesday with clouds building in anticipation of our next storm system. The first of two centers of low pressure stemming from the same upper jet max will pass through the region Tuesday night into Wednesday. Most guidance has scattered showers developing along and behind the storm`s loosely organized warm front, call it more of a baroclinic zone, and falling on the area as early as Tuesday evening and continuing on through Wednesday. Rain chances will improve through the day on Thursday as the trough approaches the Midwest. It`s at this time that the second, more robust, more concerning low will make its way into the region. A lot has changed among guidance between last night`s 00Z runs and today`s 12Z runs, namely a drastic shift southeastward in the track of this storm. The Euro now tracks the storm through the southern part of the CWA Thursday night into Friday and the GFS through the central CWA. The Euro`s solution confines the footprint of instability, and therefore the thunder potential, to the southeastern half or so of the CWA. The GFS continues to suggest that thunder is possible area-wide, but the greatest potential exists across the southern periphery of the CWA where it`s cooking up over 1,000 J/kg of MUCAPE. The shear profile, especially south of the warm front, continues to raise eyebrows with a strong low level vertical wind gradient and notable veering through the lowest few kilometers. Over an inch of PWAT also suggests a healthy amount of rain is likely across areas that spend a good amount of time in the warm sector. There is a lot more to be said with this storm, but with such dramatic changes taking place from run to run and it still being a week away, I`ll leave it at that. Nonetheless, this will be one to keep a close eye on over the next several days. Doom && .AVIATION... For the 00Z TAFs... 645 PM...Forecast concerns include... Strong/gusty west/northwest winds through the period. Chance of flurries/snow showers tonight and again Saturday. Winds will remain west/northwest with gusts into the 25-30kt range through the period. Winds will begin to diminish Saturday evening. There will be a chance of snow showers later this evening into the early overnight hours, mainly south of the terminals where there will likely be some visibility reductions. Confidence is low for snow showers over the terminals tonight. There is a better chance for snow showers across the entire area Saturday, from late morning through mid afternoon and added tempo mention during this time. These are expected to be isolated to scattered and short in duration. Thus, some areas may only see flurries. Cigs are expected to remain low vfr through Saturday evening, then begin to scatter out. Some mvfr cigs will be possible with any snow showers. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...Small Craft Advisory...IN nearshore waters until 10 AM Sunday. Small Craft Advisory...IL nearshore waters until 1 AM Sunday. && $$ Visit us at weather.gov/chicago Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/NWSChicago www.twitter.com/NWSChicago www.youtube.com/NWSChicago