Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/19/22


Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
620 PM MDT Wed May 18 2022 .AVIATION... 00Z TAF CYCLE Winds will weaken with sunset this evening, then west and southwest winds will strengthen Thursday. The strongest wind gusts should reach 30-40 KT over northern and east central areas Thursday afternoon, except for 45 KT over the high peaks of the Sangre de Cristo Mountains. Strengthening flow aloft should cause gusty conditions to linger through the evening Thursday evening in many areas. HRRR Smoke Model depicts well developed smoke plumes traveling to the east and southeast of fires through this evening, then more consistently to the southeast late tonight as fire activity slows down for the night: https://go.usa.gov/xuJbd. 44 && .PREV DISCUSSION...229 PM MDT Wed May 18 2022... .SYNOPSIS... A few storms will impact far northeast New Mexico late this afternoon into the early evening hours and may become strong to severe, producing gusty and erratic winds. Warm westerly winds will increase Thursday, with well above normal high temperatures that will challenge daily record values at a number of locales. Look for more of the same Friday, followed by a cold front late day and overnight that will bring much cooler temperatures to eastern New Mexico for Saturday. Gulf moisture will infiltrate the eastern half on Monday and set the stage for a round of showers and storms late day through Tuesday, potentially bringing much needed rain to areas along and east of the central mountain chain. Meanwhile, western New Mexico will remain warm and dry early next week. && .DISCUSSION... SHORT TERM...(TONIGHT THROUGH THURSDAY NIGHT)... Showers and thunderstorms are developing in northeast NM this afternoon in response to an increase in low level moisture last night. The storms will continue through this evening. A few could turn severe with large hail and damaging winds before exiting into TX. Elsewhere will be dry and comfortably cool with light winds. The winds aloft will turn zonal and strengthen Thursday. Moisture in the east will get shoved into TX, leaving the entire area dry and very warm with increasing winds. Isolated wind advisories may be needed in the north central and northeast areas. Critical fire weather conditions will persist for most areas. Winds will be slow to diminish Thursday night, and may increase on higher elevations of the western and central mountains. Otherwise it will be dry and comfortable Thursday night. LONG TERM...(FRIDAY THROUGH WEDNESDAY)... An upper level trough will progress east from the Great Basin toward the southern Rockies Friday, steering stronger winds aloft over NM resulting in windy conditions ahead of a cold front forecast to move south across the area late Friday into Saturday. The combination of the trough and backdoor segment of the cold front may bring a few showers or storms far northern NM near the CO border from the Sangre De Cristos eastward late Friday through Saturday. Cold air advection will be most pronounced behind the backdoor segment of the cold front across eastern NM on Saturday, where highs are forecast to be 5-20 degrees below normal. Another upper level trough will approach from over the Great Basin on Sunday and move across the southern Rockies and northern NM on Monday, drawing Gulf moisture northwest into eastern NM and setting the stage for a round of storms late Monday, with decent agreement among the 12Z medium range model solutions. A bonus round is possible Tuesday across eastern NM, but lower forecast confidence for Tue/Wed given some significant differences among the medium range model solutions beyond Monday. Specifically, the 12Z ECMWF expands a large upper high across the region from mid to late week up to near 592dam at 500mb, while the 12Z GFS continues our pattern of increased westerlies with a succession of troughs. CHJ/11 && .FIRE WEATHER... ...CRITICAL FIRE WEATHER CONDITIONS WILL RETURN THURSDAY AND FRIDAY ACROSS MUCH OF NEW MEXICO... Low level moisture moved into eastern NM last night and is hanging on today across the eastern plains. Showers and thunderstorms will impact the northeast areas through late evening, with a couple possibly turning severe. The winds aloft will increase out of the west Thursday, and mix down to the surface, sweeping the moisture in the east into TX. The combination of dry, unstable, breezy to windy conditions will create widespread critical fire weather conditions Thursday, as well as Friday. A back door cold front will impact eastern NM Friday night, with a better push south and west Saturday night, that could squeeze into the Rio Grande Valley. Low level moisture will return to the east along with a disturbance aloft passing to out north, with potential showers and thunderstorms late Friday through Saturday evening. The weekend will be much cooler, especially in the east. Sunday will be dry, but return flow moisture Monday and Tuesday could trigger showers and thunderstorms in the east. CHJ && .ABQ WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from noon to 8 PM MDT Thursday for the following zones... NMZ101>105-107-108. Red Flag Warning from 11 AM to 9 PM MDT Friday for the following zones... NMZ101>109. && $$
Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
744 PM CDT Wed May 18 2022 .AVIATION... Thunderstorms that moved southwest of DHT will likely be the last of the thunderstorm chances for DHT. More thunderstorms are expected to move southeast out of Colorado and Kansas and they are expected to affect the GUY TAF site this evening. AMA is not expected to be affected by storms. Some of the storms may become severe with damaging winds the main threat. Easterly winds are expected to turn to the southwest by early Thursday afternoon and they are expected to increase into the 15 to 20 knot range with higher gusts. && .PREV DISCUSSION... /Issued 159 PM CDT Wed May 18 2022/ SHORT TERM...Tonight through Thursday night The HRRR and FV3 are similar in their solutions on an approaching shortwave trough tracking eastward out of Colorado and New Mexico later today into tonight. Northwesterly flow aloft will allow convection that develops over the higher terrain of southern/southeastern Colorado and northeastern New Mexico by 21Z to 23Z today to move east and south into the northwestern Panhandles by 00Z Thursday. The FV3 seems to be a little more overdone and aggressive with the development of the convection with the HRRR being a little more representative but could be a bit underdone. Regardless, the convection expected to move into the western Oklahoma and northwest Texas Panhandles from southeastern Colorado and southwestern Kansas by 01Z to 03Z Thursday and then moving across the eastern Oklahoma and northeastern Texas Panhandles by 04Z to 06Z Thursday. Convection should exit the forecast area by 07Z to 09Z or so Thursday. A more zonal upper flow expected Thursday transitioning to southwesterly Thursday night. Stalled frontal boundary south of the Panhandles tonight with a moist upslope easterly surface flow will become south and southwest Thursday into Thursday night as a surface trough develops to the lee of the central and southern U.S. Rockies. Hot and dry conditions expected Thursday due to compressional heating ahead of a cold front with record or near record high temperatures possible. A Heat Advisory may ne necessary for Palo Duro Canyon Thursday with forecast high temps of 105 degrees or higher. Strong cold front forecast to push south and east across the Panhandles by 09Z to 12Z Friday. Schneider FIRE WEATHER... Thursday... Any critical fire weather conditions on Thursday will be highly dependent/conditional on where the heaviest rainfall occurs this evening and tonight. Green up prevalent on the NDVI satellite imagery to the west of Dalhart eastward and also east of a Guymon to Amarillo line. Expecting best rainfall this evening and tonight to be across the Oklahoma and northern Texas Panhandles. This places the possible critical fire weather conditions Thursday to be across the southwest Texas Panhandle where the driest conditions should be. Decided to hold off for now on issuing a Fire Weather Watch or Red Flag Warning for Thursday and may only need a Fire Danger Statement for parts of the Panhandles that are the driest and do not receive the most or any rainfall. Schneider LONG TERM...Friday through Tuesday... A cold front will begin to move through the Panhandles during the day on Friday from north to south. High temperatures will reach their peak earlier in the day before cooling down trend begins. As we approach Friday night under breezy northeasterly flow, low temperatures will range from the upper 30s to lower 50s. Cool temperatures will continue into Saturday under continued northeasterly surface flow with highs in some areas in the northern Panhandles not getting out of the 50s with the remainder of the Panhandles in the 60s. As winds subside with mostly clear skies by Saturday night, ideal conditions for radiational cooling will take place where low temperatures may get as low as the mid 30s for the northwestern Panhandles where some Frost headlines may be needed. Will watch trends closely. The remainder of the Panhandles on Saturday night will have low temperatures range from the upper 30s to mid 40s. Temperatures will moderate Sunday through Tuesday with temperatures approaching near average values for late May. As a H500 trough begins the strengthen over the Four Corners Region by Monday morning into the afternoon, H700 low centered over the central Plains will aid in the LL moisture transport into the Panhandles. With the aid of the sfc trough, showers and some thunderstorms may develop the second half of Monday. At this time, all of the Panhandles have a chance of seeing at least some rainfall. Whether it will be measurable rainfall is yet to be determined. Meccariello && .AMA Watches/Warnings/Advisories... TX...None. OK...None. && $$ 89/15
Area Forecast Discussion
National Weather Service La Crosse WI
1045 PM CDT Wed May 18 2022 .DISCUSSION...(This evening through Wednesday) Issued at 237 PM CDT Wed May 18 2022 Key Messages: - Severe storms possible Thursday - Cooler through the weekend Precipitation Overnight... Tonight, a shortwave will pass to the north of the area, bringing precipitation chances to central and northern Wisconsin this evening. Should primarily be rain showers, though with some available CAPE, thunderstorms are not out of the question. The showers will move out of the area tonight as the shortwave leaves the area. Storm Chances Late Thursday through Friday... Southwesterly warm air advection on Thursday will increase 850 mb temperatures to 13-19 C, thus increasing surface temps to the mid 70s and low 80s across the area. 850 mb moisture advection also increases Thursday, with about 1.4-1.7 inches PWAT available, which is above the 90th percentile for this time of year, according to SPC sounding climatologies. GFS is more excited about the moisture transport than the EC and also pushes higher moisture further north. The RAP suggests the greatest magnitude of moisture transport, peaking Thursday night. The models generally agree on the axis of highest moisture transport being located from northeast Iowa toward northcentral Wisconsin. A surface low pressure system to the northwest will bring a front across the area late Thursday afternoon. The warm front will align with the strongest moisture transport and warm air advection, thus creating a favorable area for storm initiation. CAMs suggest the precip would begin to affect the area late Thursday afternoon or Thursday evening. Recent HRRR runs are more excited about the precip than the RAP and also suggest a narrower band of stronger precipitation that moves east across the area. Model soundings continue to suggest that capping Thursday morning and afternoon should keep strong storms from realizing until later in the day when the cap erodes due to more daytime heating. Once the cap erodes, however, storms could become surface-based. RAP soundings suggest upwards of 3000 J/kg SBCAPE Thursday night. Steep lapse rates in model soundings combined with these high SBCAPE values favor large hail and damaging wind to occur with the storms. There is also a strong deep-layer shear of about 50+ knots; low- level shear will increase as a low-level jet strengthens, which could realize tornadoes if storms are able to tap into the shear. SPC has included our area in an Enhanced/Slight risk for tomorrow with a 30% hatched for hail. Storm total rain amounts look to range from 0.3 to just under 1 inch, with the highest amounts in SE Minnesota and central Wisconsin. After this primary round of precipitation, more storms or showers could develop along the cold front as it passes over the area. However, CAPE values decrease later in the night and a nighttime inversion could be difficult to overcome to produce more strong storms. Cooler Conditions Over the Weekend... In wake of the cold front heading into the weekend, cooler conditions are anticipated with a broad upper-level trough moving in from the west. Temperatures at 850 mb dip into the single digits would be near 2 standard deviations below the climatological mean for this time of year. The NAEFS and ECMWF ENS would place these values in the lowest 1 to 2.5 percentile. Overnight low temperatures in the mid 30s to low 40s are possible Saturday and Sunday mornings. If sky cover remains mostly clear in the overnight hours, even lower temperatures could be realized. While the end of the weekend will likely be rain free, widespread chances for rainfall returns Monday night. Will stick with the blended model guidance as models diverge on any one solution with multiple waves progressing through a near zonal flow with some solutions even showing a deepening trough over the western CONUS by mid-week. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1045 PM CDT Wed May 18 2022 While VFR conditions should prevail most of the period, several items to note in this fairly active pattern. In near term, outflow boundary from weakening showers and storms approaching KLSE TAF site may bring a temporary wind shift and brief ceilings before things clear out again. Outflow air could lead to some local fog formation overnight as well mainly north of I-90 in favored valleys. As warm front advects north on Thursday, will also have to watch for development of mid to late afternoon convection. Confidence in this scenario is lower, especially where it might occur so opted to not include in TAF sites at this time. Look for increasing winds through the day Thursday as well. Far better chance for impacts will be as cold front enters the picture Thursday evening and overnight. This will likely trigger line of convection that could impact nearly all areas with brief MVFR conditions, or at the very least VFR ceilings as this threat slides through. Wind shift will also accompany this front as it moves through headed into Friday morning. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ DISCUSSION...Dahl/Peters AVIATION...Shea
Area Forecast Discussion
National Weather Service Boston/Norton MA
1016 PM EDT Wed May 18 2022 .SYNOPSIS... Thursday will feature cool conditions, with rain in the morning, then tapering off in the afternoon from west to east. A significant warmup then begins Friday, peaking this weekend with 90 degree highs possible both Saturday and Sunday. A cold front arrives late Sunday, with the chance of showers and thunderstorms. More seasonable temperatures return for the start of the new work week. && .NEAR TERM /UNTIL 5 AM THURSDAY MORNING/... 1015 PM update... Mid/high clouds continuing to increase from west to east late this evening. Temps will continue to fall given light winds and dry airmass with dew pts in the 30s. However, overnight with clouds lowering and onshore winds developing, temps will level off. Leading edge of rain shield now moving into the Catskills of NY and Poconos of PA, and will arrive in western MA/CT after midnight, and towards morning for eastern MA and RI. It will be a chilly morning rain with temps in the 40s and 50s. Heavier/moderate rain will impact the morning commute across CT into western/central MA, including the cities of Hartford and Springfield. Farther east, steadier rains hold off until later in the morning across RI and eastern MA. Also, rain intensity may decrease somewhat as it moves east, as lead short wave deamplifies with time, as trailing short wave becomes the dominant feature. && .SHORT TERM /5 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... A mid level shortwave moves through New England on Thursday with a reflection at the surface. Isentropic lift behind the warm front will bring widespread rainfall to all of southern New England Thursday morning as warm and moist air is lifted over the dry airmass in place. Additionally, models have started to hint at a secondary low forming offshore off Long Island and crossing nearby, providing better forcing for some higher precipitation totals along the south coast. Even so, not expecting any more than a quarter inch of rain for anyone, save for potentially the islands. That being said, some of the high- res guidance like the HRRR is even drier. The highest rainfall totals will likely be along the south coast and then northwest MA closer to the parent low, with lesser amounts over central- northeast MA. A dry slot moves in at 500 mb late morning/afternoon which will cause rain to diminish throughout the afternoon and early evening. By Thursday night mid level ridging begins to move overhead once again; expecting dry conditions and clearing skies. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Highlights... * Warming trend begins Friday, with 90+ degree highs possible both days this weekend. Daily record highs may be challenged. * Cold front arrives later Sunday with the chance for showers and thunderstorms. More seasonable temperatures return for the start of the new work week. Details... The main issue during this portion of the forecast will be the heat Friday into this weekend. Latest guidance continued to slow the arrival of a cold front, so it is looking more likely that high temperatures across interior southern New England could reach the 90s both Saturday and Sunday. Onshore winds will keep the immediate coasts cooler. Heat-related headlines are likely for at least a portion of southern New England sometime this weekend. Some record high temperatures could be challenged. The Climate section below has those details. Once a cold front passes through sometime from late Sunday into Monday, then more seasonable temperatures are expected through early next week. This portion of the forecast will remain mainly dry as well. The next best chance for showers and possible thunderstorms will be ahead of a cold front sometime late Sunday into early Monday. There is a low risk for some showers towards the south coast and adjacent coastal waters Friday night. There could also be an isolated shower or thunderstorm late Saturday. It will all depend on how strong the subsidence inversion will be. At this time, thinking the greater risk for showers will be farther west. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. High confidence. Tonight... 0215z update...no change from previous TAFs. VFR and dry to start, but MVFR in SHRA approaches western CT/MA toward 06z and 12z eastern MA and RI. Earlier discussion below. =================================================================== Thursday... SHRA overspreads the region from west to east, trending toward MVFR with isolated IFR possible. Steady rain in the morning, tapering off west to east in the afternoon. South wind increasing 10-20 kt. Vsby may lower 1-3 miles in areas of fog during the afternoon and evening. Thursday night... Dry with diminishing cloudcover overnight. Winds light and variable. BOS TAF: High confidence. KBDL TAF: High confidence. Outlook /Friday through Monday/... Friday: VFR. Breezy. Friday Night: VFR. Breezy. Slight chance SHRA. Saturday through Saturday Night: VFR. Sunday through Sunday Night: VFR. Breezy. Chance SHRA. Monday: VFR. Breezy. Slight chance SHRA. && .MARINE... Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. High forecast confidence through Thursday. This afternoon...NW winds 05-10 kt, with gusts up to 20 kt. Dry weather and good vsby. Tonight...light and variable winds as high pressure remains over the waters. Then becoming south late as low pressure approaches. Chance of sprinkles in the morning. Thursday...poor vsby in rain and fog, improving somewhat in the afternoon from west to east. Thursday Night: Winds west 5-10 kt. Seas approaching 5 ft on the outer waters. Outlook /Friday through Monday/... Friday: Winds less than 25 kt. Seas locally approaching 5 ft. Friday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Saturday through Saturday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Sunday: Winds less than 25 kt. Seas up to 5 ft. Slight chance of rain showers. Sunday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers. Monday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers. && .CLIMATE... Daily record high temperatures... Sat May 21st... BOS 93F (1921) PVD 93F (1996) BDL 93F (1996) ORH 88F (1975) Sun May 22nd... BOS 93F (1959) PVD 94F (1941, 1992) BDL 95F (1992) ORH 90F (1911, 1992) && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Belk/BW NEAR TERM...Nocera SHORT TERM...BW LONG TERM...Belk AVIATION...Belk/Nocera/BW MARINE...Belk/BW CLIMATE...Staff
Area Forecast Discussion
National Weather Service Louisville KY
1012 PM EDT Wed May 18 2022 .Mesoscale Update... Issued at 925 PM EDT Wed May 18 2022 Earlier severe convection fueled by the forcing on the "tail" of the MCV overlapping with return flow/instability has weakened substantially over the last hour. More recent updrafts have tried to go up, but in an area that has been worked over by the earlier storms. Could continue to see isolated-scattered showers with a few rumbles of thunder, but the SVR threat has diminished enough that we have dropped WW 240 a bit early. Fog formation will be our other concern through the night, especially in the areas that saw substantial rain earlier. Locally dense fog can`t be ruled out, but will hold off on any headlines for the time being and just massage the extent of where we mention it. Issued at 525 PM EDT Wed May 18 2022 Did a quick update to the grids and forecast to add in Severe Thunderstorm Watch 240 which is in effect until 10 PM CDT. Updated grids and products are now available. As expected, storms have increased in intensity as they cross the I- 65 corridor. Two strong storms were being tracked at the moment. The first was over LaRue county which will pose a large hail and wind damage threat. The second storm of concern is over Marion county and this will pose a large hail and damaging wind threat. Latest mesoanalysis reveals an area of lower 80s over southern KY with dewpoints in the mid-upper 60s. This is yielding MLCAPE values of 1000-1500 J/kg. However, the lack of significant winds from obs suggests that this activity is still not fully rooted near the surface. In fact, mesoanalysis data suggests that we still have some 50-100 J/kg of CINH across much of southeastern sections. Higher values of CINH appear to the northeast across the Bluegrass region which seems reasonable given the general heavy rainfall and some embedded lightning. Further southwest, high resolution satellite imagery shows a developing Cu field trying to develop across the Karst region of central KY. We can see some agitated Cu over Logan/Butler/Warren/Hart counties where this is co-incident with higher instability values. However, bulk shear values are weaker in this area, and slightly higher over toward the LaRue/Marion county storms. Latest CAMs want to weaken some weak MLCINH over this region in the next few hours. HRRR has been hinting of convection going up around 23Z or so, so we`ll continue to monitor closely. So in terms of severity, the highest risk of severe weather exists to the southeast of the current LaRue/Marion county storms. Areas such as northern Taylor, Marion, Boyle, Casey, and Lincoln counties should prepare for strong/severe storms over the next hour. Large hail will be the primary threat along with intense lightning and wind gusts of 45-50 mph. Further north, we have some additional rounds of convection working across the Louisville metro area. This area has largely been worked over by previous convection. Trailing line of agitated Cu has been trying to develop from Jasper eastward towards Scottsburg. Last few CAM runs have been trying to further develop convection within this area, but latest few WoFS runs have been much less eager to develop anything. By far, the WoFS runs have been targeting previously mentioned areas of south-central KY (Lake Cumberland region) through about 800 PM EDT. We`ll continue to monitor the northern activity and have the option of expanding SVR box 240 if need be. && .Short Term...(This evening through Thursday) Issued at 339 PM EDT Wed May 18 2022 ...CONDITIONAL RISK OF STRONG/SEVERE STORMS THIS AFTERNOON/EVENING... ==================================== Near Term through 800 PM EDT Risks: Strong/Severe Thunderstorms Confidence: High on PoPs Low on Severe Risk ==================================== Afternoon satellite data shows a well defined remnant MCV that just crossed into Indiana from Illinois. Cluster of initially multi- cellular convection that developed over southern IL has moved northeastward and has taken on more of a linear form as it moves eastward across southern IN. Forcing has been strong enough along and just south of the vorticity max to drive/develop convection. However, model proximity soundings and mesoanalysis suggest that buoyancy has been tempered by ongoing cloudiness and limited insolation. In addition, the convection is a bit displaced from more deep/rich moisture which has been confined to western TN and far southwestern KY. The current convection is moving at around 35 knots which would place it in the Louisville Metro within the hour (reaching I-65 by around 400 PM EDT). While instability has been tempered a bit along and west of I-65, the storms will probably remain steady state as they come into the Louisville metro. Main issues here will be very heavy rainfall, gusty winds of 40-45 mph, and perhaps small to near severe hail with the strongest cores. This activity moving through the metro at the early part of the evening rush will be problematic due to ponding of water on roads along with reduced visibility. East of I-65, we`ve seen some partial clearing as high level cloud debris has mixed out and temperatures east of the I-65 corridor have increased into the upper 70s and will likely warm into the lower 80s in the next hour or two. Recent CAMs, including WoFS, have been suggestive that convection may undergo an uptick in strength east of the I-65 corridor this afternoon. This activity could be rather strong to severe as it moves eastward toward the Lexington area this evening. Further south, overall threat remains largely conditional as it will be a race to see if the MCV outpaces the moisture return to the south and west. Previous CAMs had remained pretty dry across southern KY, mainly due to a small amount of CINH just below 700 hPa. However, in the last few runs, we`ve started to see the CAMs mix out that CINH and an east-west band of convection may eventually develop across portions of south-central KY this evening. Overall confidence in this is admittingly low at this time. However, we`ll continue to monitor trends closely throughout the evening. ==================================== Overnight (800 PM - 800 AM EDT) Risks: Southern KY Thunderstorms Patchy Fog over southern IN Confidence: Medium ==================================== As mentioned above, we could see development of an east-west band of convection down across southern KY this evening. Convection may be more focused in the Cumberland Parkway corridor. Given model proximity soundings, if convection gets going, storm mode could be a mix of supercells and multi-cellular convection with a risk of damaging winds, large hail, and perhaps an isolated tornado. This activity should push east of the Lake Cumberland area by late evening. Into the overnight hours, the latest guidance keeps us rather dry with perhaps another round of showers/storms rolling through southern KY late in the overnight period. Aviation guidance has been suggestive that winds will diminish overnight and with a soupy airmass in place and recent rains across southern IN, patchy to locally dense fog may become an issue. This fog may develop a little further south into portions of north-central KY where this afternoon`s rain falls. Lows overnight will be in the low-mid 60s. ==================================== Thursday Risks: Strong/Severe Storms Confidence: Low-Medium ===================================== We should start off the day with partly cloudy skies along with some morning fog, especially across the north. A stalled out boundary should be located somewhere across southern KY and this feature is expected to move northward through the morning hours. Another in a series of MCVs is forecast to move eastward and result in additional thunderstorm development across the region in the afternoon and evening. The greatest risk of severe weather will be on the south side of this frontal boundary and ahead of the approaching MCV. Model proximity soundings show a decently unstable airmass in place with MLCAPE values in the 2300-2800 J/kg range with a bit of low- level and deep layer shear. In general, damaging winds and large hail would be the main hazardous weather threats. However, given the rather deep layer shear and speed sheer, some isolated tornadoes are possible, mainly from the bootheel of MO eastward into southern KY. Current SPC slight risk looks appropriate right now and further augmentation seems possible once the convective evolution becomes clearer. Highs on Thursday will be in the mid-upper 80s. .Long Term...(Thursday night through Wednesday) Issued at 340 PM EDT Wed May 18 2022 Synopsis...The medium range portion of the forecast will be marked by substantial amplification in the upper-level pattern as a longwave trough digs over the West and Central US and a high pressure seats over the northern Caribbean with ridge axis extending all the way to the Northeast US. The above scenario will allow the main storm track/cold front to stretch roughly from the Great Lakes towards the Texas Coastal Plains with plenty of moisture transport ahead and along of the main baroclinic zone given deep, warm-sector southwesterly flow. It is important to note that while the trough amplifies southward, a closed low over Baja California will be sheared off and the resultant PV advection will likely serve as a forcing mechanism for pre-frontal convection during the weekend. First part of the forecast enjoys good confidence on the synoptic picture; however, usual uncertainties exist with mesoscale features that will be resolved during the next couple of days. On the other hand, the forecast for next week is still pending on better agreement between main global guidance. Essentially, the deterministic ECMWF and CMC 19/12Z runs depict a more progressive flow aloft with the Central US trough slowly lifting northeast and high pressure centered over the Southwest/Intermountain West. The GFS, however, is more amplified, slower, and rather blocky with the high pressure further south over Sierra Madre, Mexico. Thursday Night - Saturday Morning...Even though rain/storm chances will be winding down past diurnal instability peak, there is a low chance of lingering convection north of I-64 after sunset associated with earlier activity that is progged to focus along a mesoscale boundary lifting through central Kentucky. The possibility of marginally severe weather, mainly for wind gusts and hail, will be conditionally determined by how the environment evolves in the early Thursday afternoon. Dry air and subsidence will provide a sunny and dry Friday as the headlines shift to the heat and possible record temperatures on Friday and Saturday. See Climate section below for more details. Saturday Afternoon - Sunday...Scattered showers and storms will be approaching southern Indiana and central Kentucky around noon on Saturday. Periods of heavy rain and lightning associated with pre- frontal convection will be common during the afternoon and evening. A few isolated and brief instances of severe weather cannot be ruled out, but overall the best dynamic and kinematic support will stay over the Midwest as the forcing attendant to the cold front passage looks very weak. The best timing for severe hail or wind could be related to pulse storms on Saturday afternoon given the lack of deep shear for organized convection. In addition, flooding concerns will have to be monitored, especially on Sunday, due to the quasi- stationary character of the main baroclinic zone and the possibility of training convection. Next Week...Precipitation chances will ultimately depend on what model blend is utilized. So far, there is warming trend in place as winds turn to the east and then to the south by midweek. Although timing and location of the rain or possible storms chances are questionable, it is safe to expect deteriorating weather conditions by midweek. && .Aviation...(00Z TAF Issuance) Issued at 755 PM EDT Wed May 18 2022 IMPACTS: - Storms possible this evening at KLEX and overnight at KBWG - Low CIGs/VIS possible across southern IN and portions of northern KY early Thursday morning - Storm chances return across the area Thursday afternoon & evening DISCUSSION: Current radar imagery shows scattered storms ongoing across east- central KY this evening, with frequent lightning being observed in storms along with brief IFR visibilities in the heavier downpours. While KHNB and KSDF are expected to remain dry into tomorrow, KLEX may still have some of these storms push through over the next couple of hours. Moving into the overnight hours, may see some additional storms develop over southern KY, possibly impacting KBWG, so have included TEMPO group to cover this potential threat, however confidence remains low. Model guidance is then suggesting some lower ceilings and visibilities may build in across southern IN, north- central KY and north-eastern KY so have included periods of MVFR to IFR conditions at KHNB/KSDF/KLEX towards sunrise. After a dry lull, chances of showers and storms will return by Thursday afternoon and evening, generally towards the end of the TAF period. Confidence is low on timing and location for tomorrow`s activity, so have only included mention of PROB30 into the KSDF planning period. Winds overnight will be around 5 kts generally out of the W/SW then strengthening out of the SW during the day Thursday with speeds between 5-10 kts. && .Climate... Updated at 350 PM EDT Wed May 18 2022 ================== Near-Record High & Warm Minimum Temperatures ===== Fri Morning Fri Afternoon Sat Morning forecast/record (date) Louisville: 72/72 (1877) 93/91 (2018) 73/72 (1877) Bowling Green: 70/69 (1998) 91/96 (1921) 71/71 (2004) Lexington: 67/69 (1996) 90/91 (1944) 70/69 (1893) Frankfort: 68/73 (2004) 91/92 (1964) 70/69 (2004) && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Mesoscale...MJ/RAS Short Term...MJ Long Term....ALL Aviation...JML Climate...ALL
Area Forecast Discussion
National Weather Service Memphis TN
837 PM CDT Wed May 18 2022 .UPDATE... It`s a quiet evening across the Mid-South in the wake of a subtle shortwave trough moving east across Middle TN. Large-scale subsidence did keep convection from developing this afternoon despite a warm and unstable air mass over the region. A few thunderstorms have developed over the Ozarks in the right entrance region of an upper-level jet max right along the 700 mb thermal gradient. The latest HRRR runs have initialized this convection but quickly dissipate it, maintaining dry weather area wide overnight. A few of the other CAMs are a bit more aggressive with convection developing along the outflow boundary just north of the MO/KY state lines. Scattered nocturnal convection near the TN/KY border remains in play as a southwesterly low-level jet near 30 kts results in enhanced convergence in this area. Will it be strong enough to produce organized convection is another question, but it`s certainly worth maintaining slight chance PoPs overnight. The potential for severe weather is pretty low given the increasing stability overnight. For tomorrow, it appears most of the convection will remain to our north, though a moist, unstable air mass could yield scattered thunderstorms around peak heating. Weak deep-layer shear should discourage organized severe weather, but a few strong storms are possible given the strong instability. MJ && .PREV DISCUSSION... /issued 332 PM CDT Wed May 18 2022/ DISCUSSION... Zonal flow aloft will continue across the Midsouth through Thursday night. The main east-west storm track will prevail to our north, from southern Missouri to the lower Ohio River valley. This corridor will be positioned south of the 250mb polar jet, extending across the upper Midwest and Great Lakes. Not especially great agreement among the short term convective- allowing models (CAMs) regarding rain chances from northeast Arkansas through the Missouri bootheel through Thursday evening. The main driver for PoPs in these areas will be scattered showers and isolated storms along the far southern periphery of mesoscale convective complexes (MCSs) moving east from the mid-Mississippi River valley into the Ohio River valley. Timing of these systems will tight to upstream convection over the central plains. Upper level ridging will push the storm track further north on Friday, in advance of a positively-tilted longwave trof over the Rockies. Model consensus over the past day have trended slower with the arrival of midlevel height falls and surface frontal passage through the Midsouth - now depicting passage through the Midsouth Saturday night. In the interim, the presence of an elevated mixed layer should cap mixed-layer CAPE nearing 3000 J/kg Saturday afternoon, accompanied by midlevel lapse rates of 8 C/km. Given the presence of the EML and weak deep layer bulk shear (< 15kts), warm sector storms will likely a difficult time developing before late Saturday afternoon. As rain chances increase Saturday night, effective CAPE will fade, limiting severe weather threat. Some uptick in severe potential may occur over north MS and the TN valley Sunday morning, until the surface cold front passes. For the Monday and Tuesday periods, today`s model consensus looks similar to yesterday`s deterministic GFS depiction of a compact shortwave ejecting from the Arklatex Tuesday afternoon. The aforementioned front will rapidly lift north as warm front Monday night, in advance of the upper wave. Similar to yesterday, medium range model consensus begins to fade by 168 hours. GFS and to a lesser extent, the Canadian depict the southern branch wave train continuing into Wednesday night, while the ECMWF weak northwest flow aloft following initial shortwave passage Tuesday night. The ECMWF ensemble mean is closer to the Canadian and GFS, suggesting unsettled weather over the Midsouth for the middle of next week. PWB && .AVIATION... 00Z TAFs VFR conditions expected through the period. Potential exists for VCTS north of JBR and MKL but confidence remains too low to include in at these sites. Otherwise, mainly rain free conditions expected through the period. S winds will diminish to 3-7 kts tonight and increase on Thursday with occasional gusts especially by Thursday afternoon. In addition, LLWS may develop at MEM late Thursday evening in response to a 45-50 low level jet developing over the Lower Mississippi Valley. CJC && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$