Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/20/22

National Weather Service Bismarck ND
1023 PM CDT Fri Aug 19 2022 .UPDATE... Issued at 1009 PM CDT Fri Aug 19 2022 Showers are diminishing across the state due to increasing stability. Patchy fog is expected to form across the central and eastern part of the state early Saturday morning. Fog is expected to be interment and locally dense at times. Patchy fog could reduce visibilities at times making the morning commute more strenuous. Thus, fog was expanded eastward into the James River Valley to match recent guidance. UPDATE Issued at 640 PM CDT Fri Aug 19 2022 Wrap around precipitation will continue to move across southeastern North Dakota this evening. Isolated thunderstorms are possible as precipiation moves southwestward, severe weather is not expected. Patchy fog could form tonight as low temperatures near the dewpoint early Saturday morning. No major updates to the current package, adjusted PoPs to match current conditions. && .SHORT TERM...(This Evening through Saturday) Issued at 227 PM CDT Fri Aug 19 2022 The main theme this evening through Saturday is a slight chance of showers this evening in the southeast and mild temperatures. Currently a few rain showers are making their way southwest through portions of the central and southeast. There has been no lightning with these, just light rain. The threat for thunderstorms looks to be low now. Cloud cover all day has not allowed the cap to break. According to SPC mesoanalysis CAPE values are 500 J/kg or less, with very low shear. The surface low is located in western Minnesota, with the upper level low slightly farther to the east. A band of showers and a few thunderstorms in northern Minnesota is wrapping around the low and moving southwest into eastern North Dakota. Along this line would be our chance for showers and thunderstorms if they either develop ahead of that line or is the line makes it all the way to our southeastern counties. Confidence is lower in the chance than this morning, CAMs either don`t have this line, or clipping Dickey and LaMoure Counties late afternoon or early this evening, which is the mostly likely outcome. Tonight clouds will clear out from west to east as surface high pressure moves in from Canada. Winds over the area will be light and variable from this, and the surface low moving out of the area. Low temperatures tonight will be in the 50s. Saturday morning looks to have clouds across most of the central and eastern areas indicated by RAP relative humidity. Timing on these clouds will be between 5am and noon CDT, then will clear out for a mostly sunny day. Temperatures will range from the upper 70s in the north, to the lower 80s in the west. The 850mb thermal ridge is just off to the west, nudging the west warmer than the rest of the forecast area. Winds will also be lighter than today. .LONG TERM...(Saturday Night through Friday) Issued at 227 PM CDT Fri Aug 19 2022 The long term will start dry with warmer temperatures, then the second half cooler with chances of rain. Temperatures: With the ridging pattern continuing, the first half of the period will be dry, with temperatures warming back into the 90s. The driving force behind the higher temperatures is the thermal ridge sliding east into the western half of the state through Tuesday. The thermal ridge is then forced south with the upper level flow flattening. Wednesday through Friday temperatures are back into the upper 70s and mid 80s. Precipitation: Upper level flow becomes more zonal in the Northern Plains Monday. A few disturbances in the flow move through, bringing the chance for showers and thunderstorms Monday evening through Friday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday Evening) Issued at 640 PM CDT Fri Aug 19 2022 Winds will remain out of the north to east tonight across the region. SHRA is possible for KJMS this evening with chances diminishing later tonight. Patchy fog could form across central and western North Dakota Saturday morning. However, confidence is low for fog formation and will be AMDs if fog forms. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Johnson SHORT TERM...Smith LONG TERM...Smith AVIATION...Johnson
Area Forecast Discussion
National Weather Service Boise ID
909 PM MDT Fri Aug 19 2022 .DISCUSSION...Showers and thunderstorms are continuing in the w-central Idaho mountains and portions of southeast Oregon this evening. Storms have produced gusts to 45 mph, and brief heavy rain. Expect activity across these areas to dissipate by midnight. An area of showers and thunderstorms propagating from east to west will track through the western Magic Valley this evening and overnight. Shower development is possible in the Owyhees towards morning. Have updated the forecast to reflect shower and thunderstorm potential through early Saturday morning. && .AVIATION...VFR. Isolated showers and thunderstorms ending overnight. Showers and thunderstorms will develop after 20/18Z, mainly over the higher elevations of central ID. Smoke layers reducing visibilities, especially south of KMYL. High density altitude due to hot temperatures. Surface winds: generally variable 10 kt or less. Gusty outflow winds up to 35kt in vicinity of showers and storms. Winds aloft at 10k feet MSL: variable up to 10 kt. Sunday Outlook...VFR with mostly clear skies. Smoke layers reducing visibilities, especially south of KMYL. High density altitude due to hot temperatures. && .PREV DISCUSSION... SHORT TERM...Tonight through Sunday night...At 2 PM MDT scattered showers and isolated thunderstorms have developed in Owyhee and Twin Falls Counties, with a few light showers in the mountains north of the Snake Basin and Baker County/OR. These are the favored areas through this evening; other areas should be partly cloudy but stay dry. Skies will clear in Oregon overnight but stay partly to mostly cloudy in central and south-central Idaho. Clouds will keep nighttime temperatures warm. Greater convective development is expected Saturday afternoon in the Boise Mountains, west central Idaho Mountains, Camas Prairie, and near the ID/NV border, as a weak Pacific upper trough moves through those areas. Behind the trough eastern Oregon will be sunny and warm. The clearer skies in Oregon will advance eastward into Idaho Saturday night, and Sunday should be mostly sunny everywhere under a short wave upper ridge, except in eastern-most Idaho mountains where a slight chance of afternoon thunderstorms is again forecast. Skies will become clear in Idaho Sunday night, but the next weak Pacific trough will bring clouds and a slight chance of showers to eastern Oregon Sunday night. High temperatures Saturday will be 1-3 degrees warmer than today, and another 5 to 7 degrees Sunday. Boise may break its record for the number of 100+ days for the season. However, smoke may hinder full heating and latest HRRR smoke model does have Sunday slightly smokier than Saturday. LONG TERM...Monday through Friday...Upper level trough passage to the north will suppress the ridge over the region beginning Monday. This will lower temperatures about 5 degrees on Tuesday. Upper level flow will remain somewhat zonal through the remainder of the period. Moisture will remain rather limited though it`s possible moisture will reach the Nevada/Idaho border by Friday. Temperatures will be several degrees above normal area-wide. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ DISCUSSION...DG AVIATION.....BW PREV SHORT TERM...LC PREV LONG TERM....JDS
Area Forecast Discussion
National Weather Service Green Bay WI
1041 PM CDT Fri Aug 19 2022 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Saturday Issued at 246 PM CDT Fri Aug 19 2022 The latest RAP analysis and satellite/radar imagery show an upper level low pressure system spinning over southern Minnesota early this afternoon. Scattered light rain showers moved northeast into central Wisconsin and parts of the Fox Valley earlier this morning, but have since dissipated as elevated moisture convergence weakened. Focus then turns to eastern Minnesota and western Wisconsin where increasing instability could interact with shortwave impulses wrapping around the parent circulation. The most robust cu currently resides over eastern Minnesota and far western Wisconsin where some thunderstorms have already developed. But with further heating, it remains possible that cu over southwest Wisconsin will develop into thunderstorms that move into central Wisconsin later this afternoon. Deep layer shear is rather weak (15-25 kts), but instability of 1000-1500 j/kg could lead to a few strong pulse storms that could produce gusty winds and heavy downpours. If storms do develop, they could approach the Fox Valley by early this evening. Tonight...The upper level low will move slowly south-southeast into Iowa. As this occurs, the axis of instability over western Wisconsin will shift east, which will prolong the chance of showers and storms well into the evening hours across central and east- central WI. An isolated strong storm will remain possible until diurnal instability dissipate by around mid-evening. Activity could remain more isolated across far northern WI so chances will be lower there. In general, precip chances will diminish during the late evening into the overnight hours though chances will remain highest over eastern WI where instability will be the highest. Short range guidance is bullish for low clouds and fog/mist developing over central and north- central WI late. Low stratus was plentiful over northeast Minnesota this morning, so this is plausible. Saturday...The upper low will continue to hang across the western Great Lakes. The day could start off rather cool and cloudy though some peaks of sunshine will develop with the heat of the day. Any sunshine will help mixed layer instability grow up to 1000 j/kg by early to mid-afternoon, and therefore should see scattered showers and thunderstorms redevelop. With shear remaining weak, the threat of severe weather is low, but heavy downpours will be possible in any storms. Highs in the low to mid 70s. .LONG TERM...Saturday Night Through Friday Issued at 246 PM CDT Fri Aug 19 2022 Medium range models are in good agreement with the upper trough weakening and exiting the region Saturday night and Sunday. They are also in good agreement with northwest upper flow from Monday through Friday next week, with a shortwave tough and surface cold front coming through Wednesday night. The upper flow is forecast to become southwest by the Saturday and Sunday, with southerly low level flow and and increasing chance of precipitation. Temperatures should be pretty close to normal next week, with the warmest day being Wednesday and the coolest next Friday. && .AVIATION...for 06Z TAF Issuance Issued at 1035 PM CDT Fri Aug 19 2022 No significant changes to the aviation forecasts are planned for the 06Z TAF issuance. Adding meaningful detail to the SHRA/TSRAs fcst across the region remains difficult. Will maintain TEMPO groups for the start of the TAFs, including TSRA over central WI where the strongest convection was located. There is also still a lot of uncertainty regarding stratus and fog potential later tonight. The NW 1/2 of the forecast area is most at risk. Rain over central WI during the evening increased the risk, though if the showers linger and skies remain cloudy conditions probably won`t deteriorate as much as earlier anticipated. Still plan to bring ST/FG into the C/N-C WI TAFS late tonight. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM.....MPC LONG TERM......RDM AVIATION.......Skowronski
Area Forecast Discussion...UPDATED
National Weather Service Hanford CA
306 PM PDT Fri Aug 19 2022 ...Updated Air Quality Issues Section... .SYNOPSIS...Temperatures will remain well above normal through Saturday then a slight cooling trend will take place Sunday into early next week before another warm-up takes place later next week. Dry conditions will continue as monsoon moisture will be limited but some afternoon cumulus clouds are likely over the Sierra Nevada each day. && .DISCUSSION...The large upper ridge over the northern Rocky Mountain region is shifting eastward as another large ridge centered near 130W builds inland in CA. The building ridge will maintain the much above normal temperatures through Saturday before a slow cooling trend takes place on Sunday and Monday as a negatively tilted trough impacts the PAC NW region and weakens the ridge over CA. With daytime temperatures expected to remain well above average on Saturday, a Heat Advisory remains in effect for the San Joaquin Valley, West Side Hills, Lower Sierra Foothills, and the Kern River Valley through Saturday. Visible imagery showing some cumulus buildups over the higher elevations of the Sierra Nevada. HRRR indicating CAPE and instability are sufficient enough for some isolated showers and thunderstorms this afternoon in the higher Sierra in Fresno and Tulare Counties. Mid level drying associated with the offshore ridge building inland will likely inhibit mountain convection on Saturday. Medium range ensemble members are in fairly good agreement with dry weather continuing through next Wednesday with temepratures remaining slightly above seasonal averages on Monday and Tuesday. Latest NBM probabilistic guidance is indicating a better than 50 percent chance for most of the San Joaquin Valley to reach the century mark on both day, but only a 5 to 20 percent chance of maximum temperatures at 105 DEG F or higher. The ridge is progged to strengthen over the region later next week which will result in another warming trend across our area and a possible return of dangerous heat in the San Joaquin Valley. RH progs are indicating mid/upper might become sufficient enough for isolated afternoon showers and thunderstorms over the higher Sierra Nevada on Thursday and Friday. && .AVIATION...VFR conditions will prevail across the Central CA interior through at least the next 24 hours. && .AIR QUALITY ISSUES...On Saturday August 20 2022... Unhealthy for Sensitive Groups in Fresno... Kern... Madera and Tulare Counties... and Sequoia National Park and Forest. && .CERTAINTY... The level of certainty for days 1 and 2 is medium. The level of certainty for days 3 through 7 is medium. Certainty levels include low...medium...and high. Please visit for additional information an/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 7 PM PDT Saturday for CAZ300>317-319-321-332. && $$ public/aviation/fire wx...DAS pio/idss...JDB
Area Forecast Discussion
National Weather Service Lincoln IL
810 PM CDT Fri Aug 19 2022 .SYNOPSIS... Issued at 203 PM CDT Fri Aug 19 2022 A slow-moving weather system will bring periods of showers and thunderstorms tonight through Sunday morning. A stretch of dry and seasonably hot weather will then return next week. && .UPDATE... Issued at 810 PM CDT Fri Aug 19 2022 Most of the convective activity this evening has been staying off to our northwest, with just a few showers tracking up the Illinois River valley. Latest HRRR has been working toward taking the more isolated supercells over southeast Iowa and forming them into more of a line, potentially moving into areas near Galesburg toward midnight. Some weakening should take place after 2 am or so as the line moves more toward the I-55 corridor. Recent forecast updates have been to work on some timing adjustments tonight and Saturday, though more work may be needed in the very short term due to impacts from some computer issues this evening. && .SHORT TERM...(This evening through Saturday) ISSUED AT 203 PM CDT Fri Aug 19 2022 A vertically-stacked, cold-core low centered over southern Minnesota will bring forth an unsettled weather pattern to start the weekend. At the surface, a cold front currently arcs from roughly Minneapolis to Sioux City to North Platte. The warm sector ahead of this front can be characterized by surface temperatures in the low 80s with dewpoints in the mid-to-upper 60s. Plenty of solar insolation and steepening lapse rates just ahead of this upper low has eroded MLCINH and has helped push MLCAPE values between 2000-2500 J/kg. A quick glance upstream reveals deep moist convection organizing along and ahead of the cold front in southwest and south central Iowa. There, parcels have benefited from a 40kt 500-mb speed max that`s effectively rounded the base of the closed upper-level low and has increased deep-layer shear. Latest CAM guidance supports this convective activity spreading eastward across the Mississippi Valley this evening, perhaps losing its punch as the 500-mb speed max diminishes in the divergent flow downstream of the upper low. Still, with a modest LLJ veering in ahead of the surface cold front, scattered showers and thunderstorms will likely persist into the overnight hours across central Illinois. While a few strong storms cannot be ruled out this evening, weakening deep-layer shear, waning surface-based instability and marginal MUCAPE should limit the severe weather potential. The better chance for severe weather comes Saturday afternoon as the cold front pushes in from the west. Model soundings around central Illinois for tomorrow afternoon resemble similar PBL conditions to what central Iowa has in place this afternoon. Thus, it`s a decent proxy to what might occur across central Illinois Saturday afternoon. With marginal CAPE/Shear profiles and a straight hodograph, a few storms may be capable of producing large hail and damaging winds. Convective activity could linger through sunset tomorrow, mainly east of the Illinois River Valley, as a LLJ again veers in ahead of the front. Storms should lose their punch, though, as the upper-level jet max becomes displaced south of our area and deep- layer shear diminishes. .LONG TERM...(Sunday through Friday) ISSUED AT 203 PM CDT Fri Aug 19 2022 The upper-level low will begin to open and shift eastward by Sunday morning as strong shortwave energy digs into the Hudson Bay. With heights increasing behind the departing upper trough and surface high pressure slowly building into the Midwest and Great Lakes regions, a stretch of dry and seasonably hot conditions are anticipated through late next week. NBM guidance is offering daily highs in the lower 80s Monday and Tuesday with overnight lows in the low 60s, and we see no reason to stray away from this guidance. Conditions then turn slightly warmer Wednesday through Friday as surface high pressure begins to depart and low-level flow veers southerly. Mid 80s will be more common to end the work week with overnight lows in the mid 60s. && .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) Issued at 633 PM CDT Fri Aug 19 2022 Timing of convection will be the main concern in the period through 12Z. While a few showers will be possible this evening, think the main thunder risk will begin around 06-07Z at KPIA and then passing KBMI/KSPI toward 09Z. Beyond that, the storms will be on a weakening trend and TSRA chances are less certain in eastern Illinois. Scattered storms expected to redevelop in the afternoon as an upper low moves into Illinois. A period of MVFR ceilings is possible near KPIA early to mid Saturday morning, but outside of that, VFR conditions should prevail outside of any temporary restrictions during storms. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Geelhart SYNOPSIS...MJA SHORT TERM...MJA LONG TERM...MJA AVIATION...Geelhart
Area Forecast Discussion
National Weather Service North Platte NE
645 PM CDT Fri Aug 19 2022 .SYNOPSIS... Issued at 320 PM CDT Fri Aug 19 2022 H5 analysis this morning had a ridge of high pressure, which extended from the Four Corners north into southern Alberta. East of this ridge, closed low pressure was noted over central Minnesota. A trough of low pressure extended to the south of this feature into the lower Mississippi Valley. West of the ridge, a decent shortwave was noted over northern portions of Nevada. A second shortwave trough was noted off the coast of western Washington State. South of this feature, high pressure was anchored approximately 700 miles off the coast of southern California. At the surface, low pressure was located over central Minnesota. A cold front extended to the south of this feature into northwestern Missouri. The frontal boundary became more westerly at that point, extending across northern Kansas into east central Colorado. Across western and north central Nebraska this afternoon, skies were partly cloudy as an abundance of cumulus and altocumulus cloud had developed across the forecast area. Cloud cover was thicker in northeastern portions of the forecast area where clouds continued to wrap around the low located over Minnesota. Temperatures as of 2 PM CT, ranged from 76 at Gordon to 86 at Imperial. && .SHORT TERM...(This evening through Saturday night) Issued at 320 PM CDT Fri Aug 19 2022 Upper level low pressure will slowly track south across southern Minnesota into northern Iowa overnight. There will be a continued threat for isolated rain showers on the western periphery of the low tonight. The threat will be greatest through mid evening in our far northeastern forecast area. Not expecting much in the way of precipitation after sunset as cooling temps should end instability. High pressure will build into western portions of the forecast area overnight. With light winds and dry air in place, temperatures may reach the upper 40s in the NW Sandhills overnight. Feel fairly confident in this forecast as the MET and MAV guidance is in good agreement. The guidance was hinting at fog potential in the northeastern forecast area tonight. However, after looking at the HRRR visby product and SREF visibility probabilities, will hold off on a fog mention for now. Will advise the oncoming shift to watch for fog development later this evening into the overnight. High pressure will slide east on Saturday with light easterly and southeasterly winds developing Saturday afternoon. Temps will be warmest in the west, where some mid to upper 80s are possible. Highs further east will top out around 80. Saturday night will see lows in the middle to upper 50s. .LONG TERM...(Sunday through Friday) Issued at 320 PM CDT Fri Aug 19 2022 Dry conditions will continue through Tuesday with ridging present across the western half of the CONUS. Highs will gradually increase into the lower 90s early next week. Beyond Tuesday, the temperature forecast becomes less certain. The latest NBM continues to be well below the latest MEX guidance and has a large spread in its members for high temps and low temps toward the middle and end of next week. This leads to a low confidence temperature forecast beyond Wednesday. As for precipitation chances, the latest NBM appears "optimistic" with its chances Wednesday, Thursday and Friday. After looking at the latest ECMWF and GFS solns from this morning, am more pessimistic about the precip forecast next week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 645 PM CDT Fri Aug 19 2022 VFR is generally expected across western and north central Nebraska overnight through Saturday evening. There is a chance MVFR ceilings will back into north central Nebraska Saturday morning. This flight concern is expected to remain north and east of KONL. VFR should be widespread in this area by 16z Saturday morning. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Buttler SHORT TERM...Buttler LONG TERM...Buttler AVIATION...CDC
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
900 PM CDT Fri Aug 19 2022 .UPDATE... Issued at 859 PM CDT Fri Aug 19 2022 Broad large scale ascent in the form of warm advection is increasing in the vicinity of the Mississippi River this evening in response to the arrival of a stout upper vort max. An initial batch of showers and thunderstorms is ongoing across parts of Winnebago, Ogle, and Lee counties, and expect this mass of convection to continue to develop and expand south and westward into Iowa. A second area of thunderstorms has recently begun to materialize farther west of the river within a zone of enhanced upper divergence at the northern terminus of a modest 60 kt jet streak. DVN radar already shows outflow racing ahead of this arcing area of thunderstorms, but additional isentropic ascent should provide the impetus to result in additional development as this feature presses east towards the region. Have increased precipitation chances after 11 PM to midnight with recent HRRR trends not looking too unreasonable. Currently, am not really expecting much of a severe threat as this main batch of convection rolls across our region late tonight with mid-level flow still being pretty weak combined with a continued gradual loss of MUCAPE as already mushy mid-level lapse rates trend moist adiabatic as the column saturates. Some gusty winds and perhaps a few instances of small hail would be about the most we expect in our area. Localized heavy rain threat certainly exists, at least until this second wave of precip helps move things along at a better clip. Upwind Corfidi Vectors are pretty uniformly expected to fall under 5-10 kts suggesting regenerative development will have the potential to train over similar areas, and can`t discount the need for a flash flood warning west of I-39 if this activity remains entrenched. Updated products have been sent. Carlaw && .SHORT TERM... Issued at 308 PM CDT Fri Aug 19 2022 Through Saturday night... A slow moving mid-level cyclone, currently over southern MN, is expected to gradually shift southeastward into the Lower Great Lakes by Saturday evening. As it does so, the area is likely to experience a couple periods of showers and thunderstorms through Saturday evening. The first wave of showers and storms is in the process of developing now across southern IA, where diurnal heating has resulted in an uncapped and unstable environment in the vicinity of a surface frontal boundary. The expectation is that thunderstorms will continue to develop across this region eastward into northwestern IL late this afternoon into the early evening as better upper level level diffluence within the exit region of an upper level jet max continues to overspread this area. These storms are expected to have an east- northeastward movement, which should allow them to shift into areas near and just west of the I-39 corridor after 7 or 8 this evening. Some locally strong gusty outflow winds will be possible through around sunset with the strongest storms, but expect this threat to wane through the evening as the cluster of shower and storms shifts eastward across the remainder of the area later this evening and overnight. Signs continue to point at a break in the activity during much, if not all of the morning on Saturday as the initial round of showers and storms weakens and moves eastward out of the area. For this reason, I have lowered POPs into the lower chance category for most areas through the morning hours, with any lingering shower activity likely to remain isolated to widely scattered in nature. Renewed thunderstorm development is expected during the afternoon though as the main mid-level disturbance begins to settle in over southern WI and northern IL. Some of these storms could become strong/severe, particularly for areas along and south of I-80, where the combination of better mid-level flow around 30 kt (and shear) looks to overlap with the better instability. The primary threat looks to be strong wind gusts, though some hail could also be possible with any supercellular structures. Locally heavy rainfall will also accompany these storms into Saturday evening. The storm threat should then gradually wane from west to east Saturday evening. KJB && .LONG TERM... Issued at 301 PM CDT Fri Aug 19 2022 Sunday through Friday... The main forcing with the upper-level low over the area on Saturday will have shifted east of area by early Sunday morning, but a secondary embedded compact wave tracking southward over eastern Wisconsin/Lake Michigan will provide lingering mid-level support into the area on Sunday. Weak dry air advection and decreasing mid- level lapse rates will greatly reduce potential coverage of showers and especially thunderstorms compared to Saturday. At this point, isolated showers in the morning will likely see some diurnal enhancement ahead of the approaching wave by early afternoon, with a localized higher area of coverage shifting south over the Chicago metro into east-central Illinois and northwest Indiana in the afternoon and early evening. NW/WNW flow aloft will prevail for much of next week, resulting in generally seasonable temps for late August. A weak embedded disturbance within a rather dry mid-level airmass may produce a few spotty showers or sprinkles across the northern CWA on Tuesday afternoon. Otherwise, the next chance of rain will be with a stalling cold front over the area late Thursday into Friday. Kluber && .AVIATION... For the 00Z TAFs... Aviation forecast concerns: * Multiple rounds of showers and storms through the period - Greatest chance late eve at RFD, SAT afternoon areawide * MVFR cigs SAT AM toward RFD, and areawide late Saturday Showers and storms: Occasional spotty showers are expected across the area this evening covered by VCSH in the TAFs. A narrow axis of isolated thunderstorms just west of the forecast area should eventually drift east toward RFD, however eastward progress remains slow at this hour. Have maintained a thunder mention at RFD from 3-7Z to account for this and other activity across Iowa. Further east it appears that lightning will be on a diminishing trend upon their approach. For now have a TEMPO for SHRA during the 6-12Z timeframe acknowledging there remains a non-zero threat for a few lightning strikes. Still think that shower coverage will diminish some Saturday morning before additional scattered showers and storms develop in the afternoon, covered by VCTS for the afternoon and PROB30 TSRA when there is slightly better confidence in greater coverage of storms near the terminals. Additional showers will remain possible at times through the evening. Ceilings: CIGS are expected to remain mostly VFR through the evening and overnight outside of any thunderstorms or heavier showers. Toward RFD cigs will begin to decrease toward daybreak with models hinting at low-end MVFR to near IFR possible through out the day on Saturday there. Confidence is lower for the Chicago area terminals on CIG trends outside of any thunderstorms. Have maintained mainly VFR through the TAF, then trending toward MVFR Saturday evening. Winds: Any lingering gustiness from earlier this evening will continue to ease with sunset. Directions will remain generally southerly (150- 210 degrees) overnight. Winds then trend WSW during the daylight hours (outside of any thunderstorm outflow influences) with speeds 10-12kt with gusts in the upper teens to near 20kt. Winds then turn light and variable Saturday evening and overnight as the upper low moves directly overhead. Petr && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
National Weather Service Morristown TN
1022 PM EDT Fri Aug 19 2022 .UPDATE... EVENING UPDATE. && .DISCUSSION... No notable changes were made this evening as the forecast remains largely on track. Coverage of showers and storms diminished fairly quickly in our area with activity continuing to our north and to our south. With continually decreasing instability, additional activity is becoming less likely, which has led to a decrease in PoPs. Also, lingering cloud cover has led to temperatures increased slightly for the next few hours with no change to overnight lows. Other elements were updated based on the latest model guidance. BW && .AVIATION... 00Z TAF DISCUSSION. Lingering showers and storms will continue to diminish this evening with most places remaining dry overnight. Low ceilings are expected to develop at CHA by the early morning hours with potential for reduction to IFR. Fog is another possibility, most likely to occur at TRI with lessened potential at TYS. Confidence for this occurrence remains limited and could yield VFR visibilities or reduction to below IFR. During the day on Saturday, any lingering low clouds and/or fog should gradually lift by closer to noon with re-development of showers and storms anticipated again. The timing for potential impacts will be earlier in the day for CHA and latest at TRI. BW && .PREV DISCUSSION... /ISSUED 330 PM EDT Fri Aug 19 2022/ SHORT TERM...(Tonight and Saturday)... Key Messages: 1. Scattered showers and thunderstorms this evening with clearing conditions and fog late tonight. 2. Chance of additional showers and thunderstorms on Saturday afternoon with the highest chances across the higher elevations. 3. Heavy rain rates may produce localized flooding issues. Discussion: Upper-level 80kt jet axis across the Southern Appalachians this afternoon is providing favorable support for ascent within an environment of 2000 J/Kg MLCAPE. PW values are 1.6 to 1.8 inches which is not anomalously high, but some heavy rain rates will be possible along cell mergers and any training. Widespread convection is expected to continue to develop through the late afternoon hours before decreasing this evening as synoptic upper support shifts northeastward and instability decreases. Greatest coverage of precipitation is expected across SE TN and SW NC and northeastward along the Southern Appalachians. Fog and low clouds are expected late tonight for those areas that receive afternoon rainfall today. We remain in a pattern of longwave troughing across the Great Lakes and Ohio Valley on Saturday with WSW flow aloft and southerly low-level flow. Shortwave ridging will actually build in across our region in the wake of a departing shortwave that enhanced precipitation coverage on Friday. The southerly low-level flow will continue to bring an increase in boundary layer moisture with chance PoPs for most locations. With the RAP showing PW values increasing to around 1.8 to 1.9 inches and MLCAPE near 2000 J/Kg during the afternoon, scattered thunderstorms are expected, especially across the higher elevations. A large warm cloud layer depth and a nearly saturated forecast sounding will favor additional periods of heavy rain rates within thunderstorms with localized flooding possible. JB LONG TERM...(Saturday night through Friday)... Key Messages: 1. There will be showers and some thunderstorms around at times for the weekend into Monday. 2. Tuesday through Thursday will see drier conditions for most, but still low chances for showers/storms mainly in the afternoons. Discussion: An upper level low entering the Great Lakes region will continue to weaken and open up as it moves east, before being reabsorbed into the westerly flow as it exits through New England into maritime Canada. While passing our portion of the country, this upper low will push a weak cold front through the area. Ahead of the front, southwesterly flow will draw moisture into our area. The combo of forcing and moisture will yield showers and storms area wide on Sunday, with a risk for localized flooding for any area that receives repeated rounds of rainfall through the weekend. On Monday the rainy weather will exit as the front pushes into Georgia. Behind the front, Tuesday through Thursday should be dry for most locations, as drier air advects in from the north. An afternoon thunderstorm cannot be ruled out in the afternoon each day, especially along elevated terrain. By Friday, greater low level moisture looks to return to give a chance for showers and storms for more of eastern Tennessee. Start of the week will be a couple degrees cooler than average this time of year, owing to the storms and cloud cover. Second half of the week post-front expect temperatures to rise back to seasonable temperatures. Wellington && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 69 84 70 83 70 / 30 50 70 80 60 Knoxville McGhee Tyson Airport, TN 67 86 69 83 69 / 30 40 60 80 70 Oak Ridge, TN 67 84 68 82 68 / 30 40 60 80 60 Tri Cities Airport, TN 63 84 67 81 66 / 30 30 40 90 60 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$
Area Forecast Discussion
National Weather Service Nashville TN
750 PM CDT Fri Aug 19 2022 ...New UPDATE... .UPDATE... Issued at 745 PM CDT Fri Aug 19 2022 Current convective activity has diminished somewhat from earlier coverage and intensity, but cells remain ongoing and the HRRR suggests that we won`t be entirely free of active weather throughout the night. Have therefore left in isolated POP`s for the duration. Evening sounding from OHX gives us a CAPE of 1,766 J/kg and a Lifted Index of -5, so the instability is definitely there, and with a weak upper trough hovering over the mid state, believe there is enough impetus for the occasional cell to develop even during the overnight period. && .SHORT TERM... (This afternoon through Sunday Night) Issued at 145 PM CDT Fri Aug 19 2022 Longwave troughing now in place across the eastern half of the US. An embedded shortwave axis is located just to the east of the MS river. PVA to the east is interacting with some afternoon warmth to promote the ongoing scattered convection across portions of the mid state. This activity will extend into the early evening hours with a chance of showers and tstms continuing for a few more hours. More of the same tomorrow although coverage will be a little higher as the low level southerly flow ramps up a touch and brings more moisture in across the area. This is all in response to a stronger shortwave upstream which will move across the mid state on Sunday and bring a good chance of showers and tstms. The deeper moisture will continue into Sunday night as well before the system pushes south of the mid state by Monday. Not looking for any severe wx on Sunday. However, 850 mb wind flow amplification will match up with greater instability levels just to our north during the afternoon. Should the mid level jet drop further south we could see a marginal risk drop into our northern counties perhaps. Otherwise, just a general risk for now. For our near term temps, looks like seasonal values through Sunday night. && .LONG TERM... (Monday through next Friday) Issued at 145 PM CDT Fri Aug 19 2022 In the extended forecast, the aforementioned system drops to our south with a weak frontal passage by Monday. Upper trough axis will be oriented n-s across the mid and southern Atlantic states. Northerly flow will extend uniformly across region so we will be under a drier and less active regime. Convective parameters on Monday will yield very low cape with afternoon subsidence prevailing. By Tuesday, some afternoon capping will also emerge and will continue into Wednesday. By the end of the week, cape to cap ratios will become a little more favorable with slightly higher pops at that time. For the extended temps, we will start out near seasonal levels for early in the week. Heights will increase with time, however, as the troughing pattern begins to break down. Temps by the end of the week will be running a few degrees above normal. 7 day precip totals do not look too bad. Euro and GFS blends suggest one half inch north up to 1 1/2 inches south. Peripheral flooding concerns are not indicated other than over Texas and the Arklatex region. && .AVIATION... (00Z TAFS) Issued at 636 PM CDT Fri Aug 19 2022 VFR conditions are expected at airports most of this TAF period although patchy fog will bring MVFR vis to CSV overnight. VCSH will be seen near BNA/MQY early this evening, then VCTS will develop again Saturday afternoon at BNA/MQY/CSV with MVFR conditions possible. Light southeast winds tonight will become south to southwest at 5-10 knots on Saturday. && .PRELIMINARY POINT TEMPS/POPS... Nashville 69 89 71 87 / 20 40 30 70 Clarksville 68 89 70 86 / 20 20 40 60 Crossville 64 80 66 78 / 20 40 50 80 Columbia 68 88 70 87 / 20 40 30 60 Cookeville 67 84 68 82 / 20 40 50 70 Jamestown 65 81 66 78 / 20 30 50 80 Lawrenceburg 68 86 69 86 / 20 50 30 60 Murfreesboro 67 88 69 86 / 20 40 40 70 Waverly 67 88 68 86 / 20 20 30 60 && .OHX WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE.......Rose SHORT TERM...21 LONG TERM....21 AVIATION.....Shamburger