Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/16/23


Area Forecast Discussion
National Weather Service Amarillo TX
702 PM CDT Sat Apr 15 2023 ...New AVIATION... .SHORT TERM ... (This evening through Sunday night) Issued at 240 PM CDT Sat Apr 15 2023 Overall, a quiet next few days weather wise is expected for the Texas and Oklahoma Panhandles. Outside of some possible very light rain showers in the north this afternoon, dry conditions will prevail through Sunday night. Below freezing temperatures are forecast for tonight for the northwestern two-thirds of the forecast area. With the growing season starting or almost starting, have kept the Freeze Warning going for tonight given the sub freezing temperatures. Near average highs return tomorrow with light winds. The latest 15/17z H500 RAP analysis indicates a trough is currently moving from west to east across the central CONUS. The base of the trough, along with some PVA is currently moving over portions of SE CO and SW KS. There is some mid level moisture across the Southern Plains as depicted by plenty of clouds moving southward across the Plains, even reaching as far south as the northern TX Panhandle. Radar is showing some very light returns entering the far NW OK Panhandle at the time of this writing. Unfortunately, the returns have been becoming less and less as the rain showers move closer to the CWA with the showers moving into an area of decreased moisture. Have kept some low end mentions of PoPs through this afternoon to account for the potential for some light rain showers in the north given the new development occurring in eastern CO. As the above mentioned H500 trough slides off to the east overnight, ridging will move across the Rockies and the eastern extent of the ridge will be across the Panhandles by late Sunday morning. With a weak pressure gradient over the area tonight combined with clear skies, temperatures should drop below freezing for a majority of the area. Even though H850 temperatures will remain approximately 5 degrees above freezing, good radiational cooling is expected given the above conditions. These warmer temperatures aloft should allow temperatures to quickly rise after sunrise tomorrow morning. The light westerly winds to start the day will eventually become southerly by early to mid afternoon. Thankfully, the winds will remain fairly light, with sustained winds in the 10 to 15 mph range. Clear skies and increasing low level temperatures will lead to highs in the 60s and 70s, which are pretty much near average for this time of year. Overall, a nice Spring day is expected on Sunday after a brisk start to the morning. Winds will remain around that 10 to 15 mph range on Sunday night as a weak surface low moves across SE CO. Temperatures should remain above freezing across the Panhandles on Sunday night. Muscha && .LONG TERM ... (Monday through next Friday) Issued at 240 PM CDT Sat Apr 15 2023 SUMMARY: Rain/storm chances could return to the southeast TX Panhandle Monday, but our focus will quickly transition to fire weather concerns for the majority of next week as the atmosphere dries out. Next week starts off warm until a pair of cold fronts Wednesday night and Friday cool us off with morning freezes possible going into the weekend. Daytime highs will be in the 80s to low 90s Monday through Wednesday, dropping into the 60s and 70s Thursday and Friday. Winds will be fairly typical for Panhandle standards, around 20-30 mph most of the week. DISCUSSION: Upper level pattern Monday will become increasingly zonal through the day, but models are beginning to come into better agreement that a subtle shortwave embedded within the flow should emerge and briefly amplify over the E TX Panhandle Monday afternoon and evening. Warm theta-e advection will be ongoing with a sfc boundary developing generally oriented from southwest to northeast through the Panhandles. MUCAPE of 500-750 J/kg should develop south and east of this boundary by 00z for high-based thunderstorms as convergence increases. PWAT values of 0.50"-1.00" would provide ample moisture for convection (especially in the southeast), but sfc dew pts still only in the 30-40 range will make for fairly dry low-levels and promote evaporative processes as precip falls. DCAPE values over 1000 J/kg along with "inverted-V" forecast soundings support that potential for strong wind gusts from these storms may need to be monitored. Medium range ensembles are in agreement with current thinking for totals to be light (.01"-.10"), but better moisture content in the southeast and moistening of the low levels as precip falls could produce localized areas of more beneficial rainfall. Considering that this morning`s 12z model suite is the first solid uptrend for this event, confidence is still somewhat low for now and have stuck with NBM POPs (around 20%). If this trend continues though, higher POPs will be needed in subsequent forecasts. Elevated fire weather conditions will also exist north of the boundary Monday afternoon. Tuesday`s precip chances for the southeast are on a downtrend with the dry line likely setting up just east of our area, leaving the Panhandles dry. Some showers/storms still can`t be entirely ruled out, but doesn`t appear likely as of latest model runs. Southwest flow aloft will kick up a lee sfc low to our north, increasing gradient winds out of the southwest (20-30 mph) and ushering in very dry air behind the dry line. This will make for solidly critical fire weather conditions in the west on Tuesday. RH recovery will be very limited overnight with min RH in the single digits across the Panhandles Wednesday, making for likely another Red Flag Warning day. A cold front moves in and helps RH recover slightly better in the north Wednesday night as another sfc low ejects eastward. Thursday will be cooler with Elevated to Critical fire weather conditions, before a stronger cold front surges our way Thursday night into Friday morning and reinforces the colder air. Harrel && .AVIATION... (00Z TAFS) Issued at 657 PM CDT Sat Apr 15 2023 For the 00Z TAFs, north winds will diminish early this evening, become light late tonight, then transition to southwesterly by mid to late Sunday morning as a surface trof of low pressure develops over eastern Colorado and eastern New Mexico. Overall, VFR conditions are expected to prevail at KGUY, KDHT, and KAMA through late Sunday afternoon. 02 && .FIRE WEATHER... Issued at 240 PM CDT Sat Apr 15 2023 Elevated to solidly critical fire weather conditions are expected all of next week. The highest threat days appear to be Tuesday and Wednesday when min RH values in the single digits combined with 20-30 mph winds will create RFTIs as high as 6 or 7 in the west. A cold front Wednesday night will help conditions recover somewhat for Thursday with elevated to near critical conditions in the south. Another cold front Thursday night will help increase RH into the teens for Friday with only elevated conditions. Fuels are still extremely dry and susceptible to fire starts, so even with winds not terribly strong for Panhandle standards, fires could start and spread easily next week. Harrel && .PRELIMINARY POINT TEMPS/POPS... Amarillo TX 33 71 46 84 / 0 0 0 20 Beaver OK 31 69 41 85 / 10 0 0 10 Boise City OK 28 68 40 81 / 0 0 0 10 Borger TX 33 74 47 89 / 0 0 0 10 Boys Ranch TX 31 73 45 86 / 0 0 0 10 Canyon TX 32 71 46 84 / 0 0 0 20 Clarendon TX 36 71 44 83 / 0 0 0 20 Dalhart TX 27 69 38 82 / 0 0 0 10 Guymon OK 30 69 40 84 / 0 0 0 10 Hereford TX 32 72 45 84 / 0 0 0 20 Lipscomb TX 33 70 42 85 / 0 0 0 10 Pampa TX 33 70 45 84 / 0 0 0 20 Shamrock TX 37 71 43 83 / 0 0 0 20 Wellington TX 37 72 43 83 / 0 0 0 10 && .AMA WATCHES/WARNINGS/ADVISORIES... TX...Freeze Warning from 3 AM to 9 AM CDT Sunday for TXZ001>009- 011>013-016-017-317. OK...Freeze Warning from 3 AM to 9 AM CDT Sunday for OKZ001>003. && $$ SHORT TERM...05 LONG TERM....38 AVIATION...02
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
951 PM EDT Sat Apr 15 2023 .SYNOPSIS... Showers and thunderstorms will accompany a cold front moving across the western Carolinas and northeast Georgia on Sunday. Gusty winds will follow the front Sunday night through Tuesday as dry high pressure develops along the Gulf Coast. A dry and warm pattern will persist through Thursday. Unsettled weather is expected Friday and Saturday as the next cold front impacts the region. && .NEAR TERM /THROUGH SUNDAY/... As of 935 PM: Some cirrus will spread in over the next few hours as blowoff from decaying convection near the Gulf Coast. However, with skies having been largely clear since sunset, cooling has occurred quickly enough for apparent decoupling and rapid cooling in some of the more rural areas of the CWA. Made some slight adjustments to temps tonight to try to capture that, but with the cirrus coming in and the expected moisture return later tonight, didn`t get too crazy with it. Lows tonight generally still should be near 10 degrees above normal. Several model sources still depict a band of showers moving into the southwestern CWA near daybreak, seemingly associated with warm conveyor belt into the low moving thru the mid to upper MS Valley. MCSs in various states of organization extend along the cold front along the eastern borders of MO and AR at this hour, falling somewhere between the HRRR and NAMNest depictions. As this activity moves farther from the upper low overnight, both models weaken the convection and it appears more likely that the WCB will be responsible for any precip in the CWA in the morning, so PoPs reflect primarily that idea. Nonetheless some MUCAPE is expected and a few rumbles of thunder probably will be embedded within. There will likely be a break in PoPs to some degree, between the early morning pre-frontal activity and convection along the cold front during the afternoon. Maintained some PoP thru the morning, but tried to depict an appropriately timed uptick in the afternoon per latest CAM consensus. The CAMs are overall unimpressed with the severe potential, although likely PoPs are still warranted across the mountains and N NC foothills. sbCAPE looks to be under 1000 J/kg but muCAPE could go higher. Effective shear forecast to be 30 kts or less which would limit organized convection, even with the front moving through. Still can`t rule out a few strong storms or even an isolated severe storm or 2. Isolated heavy rainfall possible, but overall flood threat is low. Gusty NW winds may develop behind the front late in the afternoon as well. Highs will be around 5 degrees above normal. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... As of 230 PM EDT Saturday: A cold front is expected to be moving across the Piedmont as the short-term period begins Sunday night. PoPs will quickly diminish from west to east Sunday evening as any remaining shower and thunderstorm activity moves east of the area. With a 985mb surface low lifting NE over the Great Lakes and a 1023mb high pressure propagating east along the Gulf Coast, a tight pressure gradient will develop behind the front. Therefore, the main story for the period will be the gusty winds developing behind the front in response to this pressure gradient. Sustained winds of 10-25mph are anticipated through the period, with the strongest winds during the afternoon hours each day. Wind gusts of 20-30mph Sunday night will increase to 25-40mph by Monday afternoon. While some of the highest mountain peaks may experience 45-50mph gusts on Monday and Tuesday based on the latest guidance, overall the current forecast package remains below Advisory criteria. However, this is certainly something that will have to be monitored over the next few cycles. Additionally, given the lack of significant rainfall from the frontal passage, strong winds will briefly combine with near critical RH values both Monday and Tuesday afternoon (but especially Monday), indicating fire weather conditions may be of concern. As the low pressure system responsible for these strong winds lifts into Canada during the day on Tuesday, the gradient relaxes later Tuesday as high pressure establishes itself over the Southeast and southern Appalachians. Therefore, expect wind gusts to appreciably decrease across the area by Tuesday evening. CAA behind the front will support high and low temperatures about 4-6 degrees below climo Monday and Monday night, but with high pressure moving in, Tuesday`s high temperatures quickly recover to 3-5 degrees above normal, setting up an unseasonably warm and dry start to the long-term period. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 230 PM EDT Saturday: The best weather of the long-term period is unfortunately going to be in the middle of the work week as broad high pressure slides across the Southeast into the subtropical Atlantic Wednesday into Thursday. Mostly sunny skies and a developing light southerly flow will dominate as this high pressure slides to our east later Wednesday into Thursday underneath a low-amplitude shortwave ridge. This will support high temperatures about 7-9 degrees above normal across the area both days. Low temperatures near normal for Wednesday morning will increase to about 5-7 degrees above climo Wednesday night and 7-9 degrees Thursday night. Modest height falls aloft commence later Thursday into Friday as the next system approaches the area. With subtropical ridging dominating the western Atlantic, the low-pressure track will stay well to our north near the Canadian border as a cold front approaches the region on Friday. As is often the case, bulk shear values currently in the 20-40kt range support organized convection, but the guidance is less confident about overall instability. The subtropical ridge will support a persistent S/SW fetch over the region to maintain above-normal temperatures but there isn`t a notable period of moisture flux ahead of this front. With the shortwave trough deamplifying as it propagates east into a longwave Atlantic ridge, the front is currently progged to weaken quickly as it moves across the area. At a minimum, yet another shortwave is expected to move across the Mid-South into the Carolinas for Saturday with perhaps a reinforcing cold front accompanying it. The GFS has a flatter, more progressive pattern aloft and therefore is less potent, while the Canadian and ECMWF suggest a higher-amplitude trough will impact the area. Therefore, as usual, there is quite a bit of uncertainty as to how the weather will evolve heading into Saturday. Nevertheless, unsettled weather is expected for at least the first half of the weekend. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... At KCLT and elsewhere: VFR thru at least early Sunday morning. Some cirrus will be seen overnight ejecting from upstream convection. Warm upglide will develop late tonight ahead of an approaching cold front and midlevel trough. The upglide should result in low stratocu spreading in from the SW by around daybreak, and SHRA (perhaps even an isolated TSRA) affecting the SC sites and KAVL around that time. This prompted TEMPO at KAND, just VCSH elsewhere. The associated sfc moistening will lower CCLs and suggest the lowest cigs will occur late morning to midday. The actual front looks to kick off additional SHRA/TSRA in the afternoon, with chance remaining in PROB30 range for all terminals. MVFR to IFR vsby possible in the TSRA. Shift to NW winds will occur in the evening following fropa. Outlook: Gusty NW winds are possible Sunday night and Monday before dry high pressure returns, likely lingering through the week. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...JMP NEAR TERM...RWH/Wimberley SHORT TERM...JMP LONG TERM...JMP AVIATION...Wimberley
Area Forecast Discussion
National Weather Service Lincoln IL
303 PM CDT Sat Apr 15 2023 .SYNOPSIS... Issued at 133 PM CDT Sat Apr 15 2023 Active weather will continue for central Illinois through the weekend, with strong thunderstorms this evening, showers with snow mixing in tomorrow night, and winds gusting to 40 mph or higher tomorrow and especially Monday. Summer like warmth is expected to briefly return midweek, though there will be multiple chances for thunderstorms Wednesday through early Friday as another low pressure system approaches from the west. && .UPDATE... Issued at 303 PM CDT Sat Apr 15 2023 Clearing has overspread far eastern Missouri and areas west of I-55 this afternoon, fostering increasing surface based instability and decreasing CIN, which dropped to less than 25 J/kg across all of Missouri per SPC Mesoanalysis as of 3 PM. There, robust convection has developed, and in fact baseball size hail was recently reported with the cell that just moved through Bolivar. This cluster of storms is quickly moving our way, and the latest high resolution model guidance suggests it`ll start to become our problem by around 5-6 PM, by which time some type of watch will likely be warranted for hail, wind, and a marginal tornado risk. The HRRR has been consistent the past several iterations at bringing convection with scattered to widespread 40-50 kt wind gusts through the area, with some places likely gusting above the severe threshold - mainly across our southwest counties before the storms start to weaken with loss of diurnal heating - between 7 and 11 PM. && .SHORT TERM...(This evening through Sunday) ISSUED AT 133 PM CDT Sat Apr 15 2023 <<<<<<< Key Messages >>>>>>> (1) Severe thunderstorm potential through this afternoon (2) Turning quickly colder with potential for snow tomorrow night (1) As of 130 PM, thunderstorms have quickly developed across eastern Kansas and western Missouri where mid level lapse rates are steepening as 500mb temps drop (-21C at KC already) with the approach of the upper trough from the west. Latest SPC Mesoanalysis suggests 700-500mb lapse rates have dipped below -8C/km across virtually the entire state of Missouri, save the far eastern portion where convection this morning has cooled the boundary layer. With abundant sunshine, temps were warming fast this morning across our CWA, but these have dropped a bit as remnant ouflow from those decaying thunderstorms overspread us from west to east (and even produced some brief gusty winds). This convection has served to strengthen the capping inversion, with upwards of 250 J/kg of CIN now in place across areas west of I-55. However, the clearing in its wake is impressive, and as this translates across the CWA we may be able to rewarm sufficiently to steepen low level lapse rates and prime the lower levels for renewed convective development. In the meantime, there`s still enough mid- level instability advecting our way from the west for hail producing storms to develop along remnant ouflow boundaries, and there are signs of some development already along the Missouri/Illinois state line (though the stronger activity, responsible for the severe thunderstorm watch to our west, is still a couple hundred miles away). Given the relatively dry low levels fostering inverted V type soundings, gusty to locally damaging winds will be a threat if storms become briefly surface based this evening, which is most likely if and when a QLCS can develop. Convective mode is looking messier in the CAMs, but even a loosely organized broken line could feature some localized bowing segments where one/more miniature RIJs could yield sporadic 50+kt gusts in an environment which soundings suggest may have upwards of 1000 J/kg of DCAPE. We`ll be watching closely this afternoon and evening as things evolve. (2) We`ll have lingering showers through Monday morning given abundant wrap around moisture getting pulled into the region on the back side of the surface low, and odds are some of this will fall as snow given dropping temps aloft (only one member of the LREF has 850mb temps > 0C after 3 PM CDT Sunday). HREF suggests a 70/30% prob for rain/snow in our southeast and 20/80% prob for rain/snow in our northwest by 7 PM Sunday evening, and chances are likely to increase further overnight Sunday night into Monday morning as temperatures cool a little more. NBM is only giving a 10% chance for more than 0.1" of snow accumulation, and only 14/100 LREF members have accumulations, in Peoria by Monday morning thanks to our week of upper 70s/lower 80s high temps resulting in a warm ground. We`ve got some light (sub 0.5") accumulations in the forecast for our extreme northern CWA, but this should be confined to grassy surfaces. .LONG TERM...(Sunday night through Saturday) ISSUED AT 133 PM CDT Sat Apr 15 2023 <<<<<<< Key Messages >>>>>>> (3) Guidance gives a 60% chance winds reach Advisory criteria Monday (4) Potential for frost Monday night (5) Big warm up by midweek, with severe potential returning (3) The deterministic models show the surface pressure gradient tightening Sunday into early Monday, and now HREF mean (max) has winds gusting to around 40 (45-50) mph on Monday - now looking to be the windiest day in the forecast, though only several mph gustier than Sunday. NBM would suggest around a 60% chance we`ll hit Advisory criteria Monday; chances are lower for most of the area Sunday, except in our northwest counties where the gradient will be tightest. (4) The day Monday will be windy, but precipitation should be tapering off from west to east in the early morning and clouds decreasing through the afternoon. Depending on how quickly winds ease Monday night, we could wind up with low temps in even the upper 20s across our northern counties, and with growing season now in full swing across our entire CWA we might need frost/freeze headlines to cover that potential. We`ll wait a bit to see what model trends are for winds (and cloud cover) Monday night before we pull the trigger on anything, but the concern is there. (5) If you`re over winter, don`t let Sunday and Monday get you down. Though Tuesday will be off to a chilly start, NBM suggests a ~70% (30%) chance temps will warm into the 60s (70s) in Lincoln, and Wednesday looks warmer still. Probabilities for temps exceeding 70 and 80 deg F, even at Galesburg, are around 70% and 25% for both Wednesday and Thursday. As the next storm system approaches from the west, CSU and CIPS machine learning each have a 15% severe probability contour for areas southwest of I-74 for D6/Thursday, with CIPS identifying hail is the main hazard. There`s still tremendous spread on how that system will evolve to our west, so we don`t want to sound an alarm of concern this early, but it`ll be something to bear watching with the mean of both the EPS and GEFS supporting 500+ J/kg of SBCAPE across our CWA ahead of the surface cold front, behind which another cool down is expected to close the work week and kick off the weekend. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 1216 PM CDT Sat Apr 15 2023 In the short term, the main concern is with timing of convective activity. Showers approaching KSPI/KPIA have been weakening and lighting activity has been diminishing, so no thunder mention will be included initially. Focus for thunder activity will begin from 22-24Z near KSPI/KPIA and spread east toward KCMI by 02-03Z. Brief IFR visibilities possible with the heavier rain. After that, a more widespread lowering of ceilings will take place following passage of a cold front, and ceilings near or below 1,000 feet should be in place between 09-12Z. Winds will swing to the west behind the front, and gusts 20-30 knots are likely much of Sunday morning. && .ILX WATCHES/WARNINGS/ADVISORIES... Wind Advisory from 1 PM Sunday to 7 PM CDT Monday for ILZ027>030- 036. && $$ UPDATE...Bumgardner SYNOPSIS...Bumgardner SHORT TERM...Bumgardner LONG TERM...Bumgardner AVIATION...Geelhart
Area Forecast Discussion
National Weather Service Indianapolis IN
1008 PM EDT Sat Apr 15 2023 .Forecast Update... Issued at 1008 PM EDT Sat Apr 15 2023 Overall forecast is in decent shape. Line of strong to some severe storms is approaching central Indiana from Illinois. Instability has begun to weaken with loss of heating, but enough exists ahead of the line for some of the stronger storms to survive into western portions of the area. Strong to perhaps damaging winds look to be the primary threat with this line, but some hail is also possible. Latest Evansville radar shows outflow from the line beginning to surge ahead of the line. If this trend continues, this too will help weaken the storms. Instability is already weaker to the east with dewpoints in the lower to middle 50s, and what instability there is will continue to diurnally weaken. Thus, expect the main strong to severe threat to remain in the western forecast area. By the middle of the overnight coverage of rain will diminish as the system weakens and moves farther from the surface cold front. Adjusted PoPs to reflect the above thinking. Forecast temperatures look good given colder air arriving after 12Z. && .Short Term...(This Evening through Sunday) Issued at 257 PM EDT Sat Apr 15 2023 * Last day of near record high temperatures in the 80s * Isolated shower and thunderstorm possible late evening * More widespread showers and thunderstorms overnight into Sun AM Last day of near record high temperatures across Central Indiana as a cold front will usher in much cooler and wetter conditions for the latter half of the weekend and into Monday. Surface analysis shows an area of low pressure in Central Wisconsin with a cold front extending southward down to Oklahoma. Indiana remains well within the warm sector of this approaching system as southerly flow brings very warm and moist air northward. Temperatures are already approaching 80 degrees with dew points in the 50s at most locations as of 230PM. Record high today at KIND is 84. Upper level divergence ahead of a jet streak rounding the base of a slightly negatively tilted trough to the west has placed Illinois in an area of enhanced lift within the warm sector. An area of convection has been slowly pushing eastward through IL this afternoon within the exit region of an approaching jet streak and right on the nose of an area of enhanced effective bulk shear of 50 kts. The environment ahead of it and into Western Indiana is characterized by SBCAPE nearing 1000 j/kg. While best forcing for ascent and wind shear remains over Illinois and Missouri, these storms may approach the IL/IN border 20z-00z, so have added 20 PoPs for the western few counties of Indiana. Severe weather is not expected but brief periods of heavy rain, gusty winds, and lightning are possible. Day Cloud Phase RGB and satellite lightning products already indicate the northern portion of this area of convection weakening with warming cloud tops and lowering lightning probabilities. The southern half of the convection south of I-70 looks to be holding together better and has a better chance at reaching the IL/IN border. .Tonight... Later tonight, the cold front approaches the region from the west. Latest CAMs indicate a line of storms forming along and just ahead of the cold front in an environment conducive for severe weather just to the west. With waning instability tonight, expect this line of storms to be weakening as it approaches Indiana. Increasing low level jet after sunset may be enough to keep storms going for a few hours after sunset though. Will have to keep a watch on temperatures as storms may be remain surface based if temperatures stay elevated tonight ahead of the cold front. Strong upper divergence on the lee side of the trough and 40+ kt deep, mostly speed shear, coupled with lift along the approaching cold front within a moist and unstable environment may result in a strong wind threat with the line of storms. That said, waning instability through the night should keep the bulk of the convection below severe limits. Best threat for any severe weather will be west of I-65 in Western Indiana. .Sunday... Cold front pushes through 10-15z Sunday morning from west to east with dying convection along the front. CAMs shows the front pushing through the majority of the area during the morning; however the potential is there for showers and storms to begin intensifying late morning across far eastern Indiana and the boundary layer warms and destabilizes. Expect drying conditions Sunday with increasing westerly winds and cold air advection. Temperatures will likely reach their highs around midnight and fall through much of the day into the 40s. Strong 40 kt low level jet aloft combined with steep low level lapse rates will likely result in higher gusts of 30-35 mph mixing down to the surface... making it feel even colder! RAP soundings indicate shallow moisture in the boundary layer through the day resulting in lower clouds around despite dry air advection aloft. Would not be surprised to see a light shower or sprinkle. Deeper moisture associated with a mid level disturbance on the back side of the main system approaches Sunday evening/night bringing the potential for scattered rain/snow showers. See the long term discussion for more details on the brief period of winter-like conditions Sunday night through Monday. && .Long Term...(Sunday Night through Saturday) Issued at 257 PM EDT Sat Apr 15 2023 A much cooler airmass will settle into the Ohio Valley for the beginning of the upcoming week in the wake of the Sunday morning frontal passage. The presence of the upper low and associated surface wave drifting slowly east across the Great Lakes will make for a windy and raw Monday before quickly reverting back to a warmer and quieter regime midweek. An unsettled pattern will return for Thursday and Friday as low pressure tracks from the central Plains into the Great Lakes...followed by growing signs of a reinforcing shot of cooler air for next weekend. Broad cyclonic flow and cold advection will be well entrenched across the forecast area by Sunday evening as the strengthening upper low pivots across Lake Michigan. Raw...brisk and windy conditions are expected through late Monday with a rude reminder that April can still offer up chilly conditions more akin to late February and early March. The lower levels will become cold enough by late Sunday night and continuing into Monday to enable flurries or light snow to mix in with rain...primarily focused across northern portions of the forecast area. Even with a few heavier snow showers or graupel likely as low level lapse rates steepen...not expecting any impacts locally as ground and surface temps will remain warm. A few spots may pick up a quick dusting on the grass and elevated surfaces before melting. Skies will remain cloudy with slow clearing from the southwest Monday as the upper low moves away. The potential for some sun Monday afternoon may enable temps to warm into the low and mid 50s across the southwest half of the area...with 40s expected elsewhere. Lows on Monday night will dip into the low and mid 30s across much of the area...but frost is likely to be largely mitigated by continued breezy winds Monday night. There is a greater risk for frost accrual Tuesday night as winds lighten...but this will remain largely confined to northeast counties in the forecast area where the coldest temperatures are expected. High pressure and ridging aloft will enable a quick warmup with highs back into the 70s by Wednesday and Thursday. A frontal boundary will set up over the Great Lakes by Thursday with a trailing surface wave organizing over the Central Plains. The low will track northeast into the Great Lakes by Friday...pulling a cold front through the Ohio Valley. Scattered convection will be possible Thursday and Friday but the overall risk for severe storms is likely to remain to the southwest of the region where instability and low level moisture will be more plentiful. Showers may linger into the first half of the weekend as well with a trailing upper level wave behind the front. The bigger impact from the frontal passage late Friday or Saturday will be to usher another cooler airmass across the Ohio Valley and Great Lakes for next weekend with temperatures 10-15 degrees below normal and renewed potential for a couple of frosty mornings. With a more amplified upper level flow pattern across the country in the 7- 10 period...hints are there at cooler temperatures lingering into the last week of the month. && .Aviation...(00Z TAF Issuance) Issued at 649 PM EDT Sat Apr 15 2023 Impacts: * Showers and scattered thunderstorms move in mainly after 03Z * MVFR conditions possible in convection, then become widespread toward 12Z Sunday * S to SE winds tonight become gusty SW to WSW Sunday with gusts around 30kt possible Discussion: Weakening area of convection will move in from the west mainly after 03Z. Some gusty winds and MVFR or worse conditions possible in stronger convection. This area will continue to weaken and diminish overnight, but additional showers and perhaps a thunderstorm will develop Sunday morning with the cold front. Widespread MVFR ceilings are expected Sunday. After the cold front passes, stronger winds will arrive. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ Update...50 Short Term...CM Long Term...Ryan Aviation...50
Area Forecast Discussion
National Weather Service Nashville TN
755 PM CDT Sat Apr 15 2023 ...New UPDATE... .UPDATE... Issued at 747 PM CDT Sat Apr 15 2023 With a SVR Watch now posted up against Middle TN and an active line of thunderstorms approaching the MS River, I thought now would be a good time to talk about our current environment. Thanks to temperatures still in the mid 70s, current RAP analysis shows around 1000 J/Kg of CAPE in our far northwest counties along the TN River. This number is expected continue falling as we lose the heating of the day, but when the line gets to the TN River, we should still be holding onto about 500 J/Kg. That means storms will have a little energy to feed off of and with bulk shear values of 20-30 kts, we could eek out a strong wind gust close to the TN River, but we still expect the line to weaken even further as it approaches the I-65 corridor. I think we can still expect lightning and a few winds gusts of 30 mph with the arrival of the line in any given area, so for any outdoor events, you`ll have to take this into consideration. Timing still looks pretty good, with arrival at the TN River around 10 pm and into the I-65 corridor maybe 1 to 1.5 hours later. Have tweaked the grids to refine current arrival times and rain chances, but everything is pretty much on track. && .SHORT TERM... (This afternoon through Sunday Night) Issued at 119 PM CDT Sat Apr 15 2023 The 12Z OHX sounding showed a pronounced temperature inversion caused by some nice overnight radiational cooling. A foggy cool morning has given way to a beautiful warm afternoon. Bumped highs up a degree or two as the area will be squeezed by the incoming low pressure system tonight. The trough axis is currently across the midwest with a developing surface low slowly trekking this way. Latest CAMs continue to show a line of storms falling apart as they cross the Tennessee River late tonight, with a few pre- frontal storms possible this afternoon. Model soundings are also hanging on to a cap tonight, so severe potential continues to looks very low. The cold front looks like it will pass through overnight tonight, really anytime after midnight. The greatest instability exists this afternoon; a couple hundred J/kg at most. Shear and helicity values are very low. With that cap in place, any pre-frontal storm development will have a very difficult time tapping into what instability is there. Once the main line actually approaches, CAPE and shear values will be even lower. A strong storm or two will be possible across the mid state overnight, but widespread severe weather does not appear to be the case with this system. QPF values are not impressive. Areas across the northwest will receive the most rain, with anywhere from 0.20-0.75" possible. Values in areas along I-40 and east are less than 0.15". Showers will clear the area by Sunday afternoon, leaving us with temperatures in the mid 60s. Sunday will be breezy as we are going to be on the back side of that tight surface low. Gusts up to 30mph will be possible. As that low moves further off to the northeast, winds will die down and should be calmer after sunset. Sunday night lows will be in the mid 40s. && .LONG TERM... (Monday through next Saturday) Issued at 119 PM CDT Sat Apr 15 2023 We will be under the influence of a ridging pattern starting Monday which will give us a few really beautiful days to start the new work week. A gradual warming trend will ensue Monday as winds slowly shift from westerly to southerly through Wednesday. Current forecast highs range from 69 on Monday to 81 on Wednesday. Monday will be a breezy day caused by another tight gradient. Sustained winds will be around 20mph with gusts of anywhere from 30-35mph through the afternoon. Expect these to calm down Monday evening. The next shift in our upper- air pattern will be Wednesday when a shortwave passes over the area. For now, this looks like it will only bring an increase in clouds for Wednesday afternoon. Thursday, however, will mark the start of a more active weather pattern. Models are in good agreement with a deep trough setting up over the Pacific Northwest and traversing the northern half of the country, organizing a surface low that will bring a chance for storms across Middle Tennesse Thursday evening-ish. The exact placement of the surface low varies between models, so for now, anticipate the next chance for weather to be Thursday. Beyond that, rain chances stick around through Saturday. && .AVIATION... (00Z TAFS) Issued at 630 PM CDT Sat Apr 15 2023 This taf cycle will begin with a few hours of VFR at all terminals. Overnight, showers and scattered thunderstorms will cross the area ahead of a cold front. Mainly MVFR will occur with the showers and storms, and wind gusts around 30KT are likely with the stronger cells. An abrupt wind shift from south to west is expected with frontal passage 11Z-16Z. Gusts near 25KT will be common after fropa and through the day on Sunday. Cigs will gradually improve from MVFR to VFR on Sunday. && .PRELIMINARY POINT TEMPS/POPS... Nashville 56 66 46 69 / 80 20 0 0 Clarksville 52 61 44 68 / 90 10 0 0 Crossville 54 65 40 61 / 70 70 0 0 Columbia 53 64 44 68 / 90 10 0 0 Cookeville 56 65 42 63 / 70 60 0 0 Jamestown 54 66 41 61 / 70 80 0 0 Lawrenceburg 54 65 44 68 / 80 10 0 0 Murfreesboro 55 66 44 68 / 70 20 0 0 Waverly 49 61 45 67 / 100 10 0 0 && .OHX WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE.......Unger SHORT TERM...Baggett LONG TERM....Baggett AVIATION.....Unger
Area Forecast Discussion
National Weather Service Paducah KY
656 PM CDT Sat Apr 15 2023 .UPDATE... Updated aviation section for 00z taf issuance && .SHORT TERM...(Tonight through Sunday night) Issued at 240 PM CDT Sat Apr 15 2023 Thunderstorm potential remains the main concern through tonight. A cluster of elevated thunderstorms developed over south central Missouri this morning, associated with strong theta-e advection in the 925 to 850 mb layer. This cluster has persisted into the mid afternoon hours as it crosses the Mississippi River. The storms are likely becoming surface based as the intensity has ticked up and convective inhibition has been eliminated in the latest spc mesoanalysis. These storms will continue moving northeast through late this afternoon into an area of weaker instability and marginal shear. The more organized severe weather potential is to our west, where a Severe Thunderstorm Watch has been issued for southwest Missouri. Isolated severe storms over southwest Missouri as of 19z are forecast to increase in coverage and intensity as diurnal heating raises mixed layer capes to between 2000 and 3000 j/kg. The storms are developing near a cold front, which will track eastward across our region tonight. Based on 12z href data, the storms over sw Missouri are likely to grow upscale into broken lines or clusters as they reach the Current River area of southeast Missouri around 22z-00z. Large hail potential will exist given mid-level lapse rates approaching 8 C/km. Shear is not particularly strong compared to other events over the past couple months, however it is sufficient for organized severe storms. The latest rap model run indicates 0 to 6 km shear around 35 kt as the storms move through, with the higher values generally lagging behind the storms tonight. The 12z href does indicate an increase in low level winds tonight, up to around 35 kt at 850 mb this evening across the region. The strengthening low level flow could be sufficient for an isolated tornado or two. 12z href data shows 0 to 1 km helicity peaking early this evening between 100 and 200 this evening near the Mississippi River. As the cold front moves east tonight, the storms will progress eastward into a more hostile environment over sw Indiana and the Pennyrile region of west Kentucky. The severe weather potential will wane after 03z (10 pm), when instability is forecast to diminish substantially with loss of daytime heating. Gusty west winds and much cooler temps will be the main story on Sunday. Steep low-level lapse rates and lingering moisture will promote widespread low clouds on Sunday. There may even be some instabilty sprinkles or showers in southwest Indiana and adjacent areas. Highs will be in the 50s, except reaching the lower 60s where skies clear out in the downslope areas of the Ozark foothills. A gradual clearing trend will occur from southwest to northeast on Sunday night. Winds will remain at least 10 mph overnight, which will inhibit radiational cooling to prevent frost potential. Lows will be in the lower 40s. .LONG TERM...(Monday through Saturday) Issued at 240 PM CDT Sat Apr 15 2023 The long term portion of the forecast period will begin with the region under broad cyclonic flow at the mid-levels, with a longwave trough positioned across across the northern Great Lakes. Strong west-northwest surface flow with gusts of 30-35 mph will advect a very dry airmass into the region on Monday. Combined with high temperatures in the 60s to lower 70s, minumum RH values will be 20 to 25% across the forecast area. With short fuels remaining fairly dry, elevated fire weather conditions will be a concern. Will include a mention of elevated fire weather conditions in the HWO for Monday. Tuesday into Wednesday will see the region come under the influence of mainly zonal mid-level flow. This will bring a warming trend in temperatures along with increasing dew point temperatures as southerly flow surface increases. High temperatures on Tuesday will reach the lower to middle 70s...followed by values in the middle to upper 70s on Wednesday. A passing ripple in the zonal flow may kick off a few light showers Wednesday afternoon, but most locations will remain dry. Our next widespread rainmaker will arrive Thursday into Friday in the form of an approaching cold front. This front will be associate with yet another dynamic surface low that will develop on the lee side of the Rockies, then move northeast into the Great Lakes region. High temperatures will reach the upper 70s to lower 80s Thursday. Dew point temperatures will creep into the upper 50s to lower 60s across southeast MO Thursday afternoon. Combined with the dynamic front, this could be enough to support strong to severe thunderstorm develop Thursday afternoon into Thursday night. SPC has this are outlooked under a slight risk in its Day 6 Outlook. The PoPs will continue into Friday as the front progresses through the region. As it typical with the NBM, it keeps the mentionable PoPs lingering through much of the day Friday due to timing differences. Suspect that we`ll be able to tighten up the ending time of the rain as the event approaches. High temperatures Friday will range from the middle 60s to around 70 degrees. && .AVIATION... Issued at 656 PM CDT Sat Apr 15 2023 A cold front will move east across the region tonight, preceded by a round of strong thunderstorms. A period of ifr conditions remains in the kpah/kcgi/kmvn tafs before midnight. The storms will likely contain gusty winds. Further east, as the storms encounter drier and less unstable air, the storms should weaken by the time they reach sw Indiana and nw Kentucky. The tafs still contain some mvfr conditions there, but any ifr conditions should be too brief for the tafs. Following the frontal passage, winds will become gusty from the west. Widespread mvfr cigs will arrive behind the front and continue through much of Sunday. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ SHORT TERM...MY LONG TERM...DWS AVIATION...MY