Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/22/24


Area Forecast Discussion
National Weather Service Bismarck ND
946 PM CDT Wed Aug 21 2024 .KEY MESSAGES... - There is a slight risk (level 2 of 5) for severe weather across western and parts of central North Dakota this evening and overnight, with medium to high chances (40 to 75%) for showers and thunderstorms during the same time period. - Temperatures are forecast to warm from Thursday into the weekend, with highs in the mid 80s to mid 90s on Saturday. && .UPDATE... Issued at 946 PM CDT Wed Aug 21 2024 We continue to monitor severe storms over eastern Montana that are slowly approaching western ND. It looked like they may have been trying to better organize but latest radar trends don`t appear to be supporting that. Once again for the forecast there were no major changes. There were some minor adjustments to POPS for timing and coverage. The forecast still brings the area of convection into ND as the upper level shortwave continues to approach, with the convection progressing eastward and out of our CWA by tomorrow morning. With ample instability still in place along with 0-6 km shear around 40kts and a low level jet at play (850mb winds from the south around 30-40 kts), there is still the risk of strong to isolated severe storms overnight. UPDATE Issued at 653 PM CDT Wed Aug 21 2024 No significant changes were made with this update. Satellite imagery continues to show widespread low stratus hanging on over approximately the eastern half of the state. The expectation with regard to strong/severe storm potential, especially over western ND, remains the same as well. Currently we have a Severe Thunderstorm Watch just to our southwest stretching across portions of MT and SD. Latest SPC mesoscale discussion mentions possible expansion of the Watch into western ND. Latest SPC mesoscale analysis continues to show 2000-3000 kg/J of CAPE over western ND with 0-6km shear generally around 40kts and expected to increase with the approaching wave. Latest HRRR continues to show a fair amount of CIN in place, including western ND, which may aid keeping storms in check at least initially. Storms have been relatively slow to develop to our west, but expect more activity as the upper level shortwave continues to approach the region. && .DISCUSSION... Issued at 304 PM CDT Wed Aug 21 2024 This afternoon, the synoptic pattern across the CONUS was characterized by omega blocking, with the central ridge just east of the forecast area leading to southwest flow over the Dakotas. An embedded shortwave was rounding the base of the western trough, passing over the Northern Rockies, with a deepening surface low in north central Wyoming. An attendant surface trough was oriented generally north-south with the low, with a cold front to the northwest of the surface trough. Low- level warm air advection was overspreading eastern Montana and western North Dakota ahead of the incoming wave, although plentiful moisture in the southeasterly surface flow has led to persistent low cloud cover across much of southern and central North Dakota, as well as northern South Dakota. Daytime satellite imagery shows mostly clear skies across eastern Montana into Wyoming, with signs of somewhat agitated cumulus developing in these areas. The general expectation is that as the shortwave approaches and heights fall ahead of the trough base, scattered convection will develop off of the higher terrain in Montana and move east towards the forecast area. The current environment in eastern Montana into western North Dakota is characterized (per SPC mesoanalysis) by 2000-3000 J/kg of MUCAPE, steep mid-level lapse rates, and bulk shear on the order of 30-40 knots. Dew points and subsequent instability increase to the east across this focus area before dropping off across central North Dakota, especially now that cloud cover has been so persistent. Our thinking is that shear will increase through the evening and into tonight with the approaching wave, with the addition of a low-level jet kicking in late this evening. Capping is certainly a concern when it comes to the threat ceiling, as well as storm mode, which we are uncertain of. High-res guidance has been changing pretty consistently over the past few cycles. If storms end up staying more discrete, will likely be a larger hail threat, but there have been some signs of a more multicell/cluster storm mode with deep layer flow more parallel than perpendicular to the surface trough. Although DCAPE is over 1000 J/kg across western ND, 0-3 km shear is forecast to generally stay under 25 knots, and there is low confidence in a linear storm mode. We did discuss messaging a higher wind threat than 60 mph, as there has been some mention of higher magnitude wind potential over western North Dakota, but we feel as though this is a rather isolated threat and will be primarily focused over eastern Montana. SPC did expand our Slight Risk (level 2 out of 5) earlier today, which seems fair given the expanded area of favorable overlap compared to what previous guidance was advertising. What has been consistent in CAMs is for an initial push of convection in southwest North Dakota this evening, before the main area moves in from Montana late this evening into the overnight hours. If we don`t see more clearing in the southwest part of the state over the next few hours, capping concerns come into play which could keep convection sub-severe. Blended guidance has sped up precipitation timing just a bit through the night, with showers and thunderstorms entering northwest North Dakota in the late evening, quickly expanding east through the forecast area and ending in the James River Valley Thursday morning. With the faster timing, our Marginal Risk (level 1 out of 5) has been significantly trimmed back which seems quite fair, given the bulk of precipitation should be out of the forecast area before we can get much in terms of heating and instability. However, it will be dependent on how things progress overnight, and we will still likely have scattered showers and thunderstorms across the area, but it is more likely they will stay sub-severe. After storms clear out on Thursday, skies will clear from west to east as well, with highs mainly in the 80s. We begin a modest warm up through the end of the week as flow is generally zonal, with a shallow ridge building in downstream of a deepening trough over the western CONUS. Highs will peak on Saturday in the mid 80s to mid 90s, with low but non-zero chances for showers and thunderstorms on Friday and Saturday. The general trend has been for the aforementioned trough to move into the central CONUS to start next week, although there are differences in timing among ensemble clusters. Regardless, blended guidance is showing cooler temperatures and increased chances for precipitation to start the work week, with a potential additional cooldown late next week. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 653 PM CDT Wed Aug 21 2024 A low stratus deck continues to bring MVFR conditions to KBIS and KJMS. Satellite imagery indicates this should continue, with a slight westward expansion of the clouds evident. We continue to expect showers and thunderstorms to spread into western ND and progress eastward. Given uncertainties in coverage and timing, the forecast continues to carry VCTS for all terminals. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...JNS DISCUSSION...Jones AVIATION...JNS
Area Forecast Discussion
National Weather Service State College PA
1125 PM EDT Wed Aug 21 2024 .SYNOPSIS... *Early taste of Fall fades with seasonal warmup by the weekend *Summertime conditions return for the last week of August && .NEAR TERM /THROUGH THURSDAY/... Lake clouds and residual remnant clouds from earlier light shra extend from the NW Mountains to the Lower Susq late this evening. These will continue to entrain and decrease through 06z with most areas becoming clear to partly cloudy for the balance of the overnight. Clearing skies, dry/low pwat air and light winds associated with surface high pressure will result in another unusually cool night by August standards. We continued to trend min temps toward a blend of persistence (last night`s obs) and below the 25%tile NBM. Air/water spreads and synoptic setup will also be favorable for fog development particularly in the north central river/stream valleys. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... Improving conditions start Thu as the upper low begins to lift as 1024+mb sfc high slides over PA. This will translate into dry weather and decreasing NW breeze. Partly to mostly sunny skies with max temps in the upper 60s to mid 70s trend warmer day/day, but remain 5-10 degrees below late August climo. Another seasonably chilly night on tap for Thursday night with nearly ideal radiational cooling under the center of the surface high. This signal also supports more valley fog into early Friday morning. Summertime conditions then make a comeback by late week and into the weekend, with a warmer return southerly flow developing Friday as the high slips off of the East Coast. Expect min temps to begin a series of higher lows with max temps trending near to above the historical average into the upper 70s to mid 80s by the weekend. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Humidity and temperatures continue to increase throughout this weekend thanks to southerly return flow behind retreating high pressure. We could see an isolated shower into the middle of next week, but most of the time should remain dry. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... 03Z Update...Forecast generally remains on track, although have added SCT003 decks in the 08-12Z timeframe at BFD/IPT/UNV with calm winds at these locations and generally SKC conditions. RAP model soundings are tracking closely but generally keep lower levels just dry enough to dissuade from adding FG mentions at this time so have kept mentions out of the TAFs at this time due to lower confidence. Previous Discussion (Issued 7:29PM EDT 8/21/2024)... A broken-to-overcast deck between 5-8kft AGL will continue over the next hour (or two) before becoming more scattered in nature after 03Z Thursday. The light showers across east-central PA have generally tapered off and do not expect any SHRA mentions through 00Z Friday. There is moderate (50-60%) confidence in prevailing VFR continuing through 00Z Friday at all airfields outside of BFD/IPT/UNV. Clearing skies overnight with winds dropping off (light and variable to near calm between 07-12Z Thursday) will lead to patchy valley fog formation with slightly higher confidence closer to IPT/UNV than BFD. The main concern with fog formation will be some lower- level dry air outlined in model RAP soundings that could limit this potential. At this time, have kept mentions to VCFG for these airfields although subsequent TAF packages might have higher confidence to include visibility and/or ceiling restrictions. After any (potential) fog mixes out in the 13-14Z Thursday timeframe, expect VFR conditions to prevail through 00Z Friday with high (> 90%) confidence. Cloud coverage does not look to be as widespread on Friday, but a broken 6-8kft AGL ceiling with gusts in the 15-20KT range appear possible through the PM hours. Outlook... Fri-Sun...Patchy AM fog; otherwise, VFR w/ no sig wx. Mon...Mainly VFR. Isolated PM SHRA/TSRA possible NE. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...DeVoir/Steinbugl NEAR TERM...DeVoir/Fitzgerald/Steinbugl SHORT TERM...DeVoir/Fitzgerald/Steinbugl LONG TERM...DeVoir/Banghoff/Gartner/RXR AVIATION...NPB
Area Forecast Discussion
National Weather Service Cheyenne WY
951 PM MDT Wed Aug 21 2024 .KEY MESSAGES... - Scattered to numerous showers and thunderstorms are expected on a daily basis for the foreseeable future, some with locally heavy rainfall. Isolated strong to severe thunderstorms will be possible at times as well. - A drying trend will arrive by Sunday with the potential for increased risks of Fire Weather concerns through early next week. && .SHORT TERM /THROUGH FRIDAY/... Issued at 257 PM MDT Wed Aug 21 2024 Today and tomorrow will feature active weather over southeast Wyoming and western Nebraska. A classic monsoon pattern is evident over the southwestern CONUS with a ridge of high pressure in place and seasonably high PWAT values around 1-2 standard deviations above the normal. Forecast soundings this afternoon indicate that much of that moisture is above a deeply mixed boundary layer present anywhere along and west of I-25. Deep inverted-V soundings generally favor strong wind gust potential and that threat will be present especially if any stronger storm cores can form over higher terrain and descend eastward through the afternoon and evening hours. There is also a dry lightning threat given large T/Td spreads at the surface, highlighted as well by the SPC Astride outlook over east- central Wyoming today. Farther east and south over far southern Wyoming and into the Nebraska Panhandle, a very modest amount of west-southwest mid and upper-level flow is present resulting in bulk shear values in the 20-30 knot range. Given this weak shear overlap with better surface moisture (Tds in the mid to upper 50s) and SBCAPE values near 2000 in the NE panhandle, one or two severe thunderstorms are possible later this afternoon after any MLCIN is eroded. CAM guidance supports the idea of eastward propagation of any convection which will likely end before around 8pm this evening. Overnight, expect more mild temperatures with scattered to broken cloud ceilings helping to prevent better radiational cooling. A very similar setup is expected on Thursday over southeast Wyoming and western Nebraska. Convection is first expected to initiate over the higher terrain of the Snowy, Sierra Madre, and Laramie ranges by 19z or so and spread eastward throughout the afternoon. Height rises at 500mb and associated warming mid-level temperatures will help sustain capping throughout the early afternoon, perhaps resulting in a bit weaker convection east of I-25. However, a subtle vort max/weak wave of faster flow aloft moving through by sunset may help touch off a few storms farther east in the NE panhandle. Cloud cover should help reduce afternoon highs somewhat from past days. Overall, HREF ensemble guidance is in good agreement through the forecast period. Primary adjustments to the forecast on Wednesday and Thursday were to raise overnight low temperatures given the cloud cover forecast and nudge PoP values slightly upward. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Issued at 257 PM MDT Wed Aug 21 2024 The monsoonal pattern is expected to continue with plenty of moisture. With a southwesterly flow, Carbon and Albany county could begin to see a slight chance of scattered thunderstorms after noon. Convection could then spread east to the rest of southeast Wyoming. The Nebraska panhandle seems to look pretty dry until 6 p.m, when scattered storms could impact the area. So far, the chances of these storms impacting the CWA being severe is on the lower side due to minimal wind shear, though not impossible. Minimum temperatures look to hover in the mid 60s in the Nebraska Panhandle and upper 50s to low 60s in Southeast Wyoming. The higher elevations of the Medicine Bow and Sierra Madre Mountain ranges have an 80% chance of seeing minimum temperatures in the low to mid 40s. As for maximum temperatures, the mountainous areas will likely see highs into mid to upper 50s. Carbon and Albany county will see cooler temperatures than the rest of the CWA around the upper 70s, with the rest of southeast Wyoming and the Nebraska Panhandle seeing upper 80s and low 90s. The weekend forecast will center around a trough of low pressure moving through the northwest CONUS and how it interacts with residual monsoonal moisture to the south. As of the 12z ensemble guidance cycle today, southwest flow aloft will increase on Saturday and Sunday as this trough approaches. Forecast guidance indicates that the majority of deeper surface moisture will be shunted eastward into the high plains, east of the NE panhandle thus limiting the overall threat of severe weather despite better wind shear/flow aloft. However, if the speed of this trough slows enough, Saturday afternoon could feature a more robust severe threat in the eastern plains/NE panhandle if enough surface moisture/upslope surface flow can remain in place. By Sunday, most ensemble members drive a hot, dry and deeply mixed southwesterly flow environment over the entire CWA resulting in a mainly dry day. Fire weather/Red Flag concerns may become relevant on both days if RH values can remain below 20%. Dry weather will continue on Monday and Tuesday over southeast Wyoming and western Nebraska as a westerly flow regime remains in place. Expect temperatures to remain above average through the period. Forecast confidence remains high through the long term with slight adjustments made to PoP grids during the afternoon hours. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 946 PM MDT Wed Aug 21 2024 Concerns for the 06Z TAFs deal with low stratus in the Panhandle Thursday morning. KAIA and KSNY did get quite a bit of rainfall this evening...which will help with low level moisture. Latest HRRR guidance showing possible IFR/LIFR ceilings at both airports around 12Z tomorrow morning. Decided to bring KAIA and KSNY down to 500 foot ceilings 12Z to 15Z. Then showers and storms Thursday afternoon for most airports. Maybe not as numerous as Wednesday...but the threat is still there. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...MAC LONG TERM...MN/MAC AVIATION...GCC
Area Forecast Discussion
National Weather Service Dodge City KS
509 PM CDT Wed Aug 21 2024 ...Updated Aviation... .KEY MESSAGES... - Showers and sub-severe thunderstorms are likely tonight along and north of KS-96. - Another round of showers and thunderstorms is possible tomorrow evening into the overnight, which may be marginally severe. - Afternoon temperatures in the 100-105 range are expected on Saturday. && .DISCUSSION... Issued at 200 PM CDT Wed Aug 21 2024 No change to the short term forecast this cycle as southwest KS remains under the influence of a mid-level cut-off ridge centered over the southern and central plains, with a pair of troughs on either side as per latest water vapor satellite imagery and RAP analysis. At the surface, temperatures have warmed into the 80s for most areas, save for roughly the central third of our CWA where a stratus deck was in place much of the morning. Visible satellite shows this deck has mixed out completely, with full sunshine now common which will support afternoon highs in the upper 80s to upper 90s. Tonight into the early morning hours, HREF members indicate scattered showers and thunderstorms are likely along and north of KS-96, as probability of QPF > 0.01" is in the 60-80% range. Any thunderstorms will be sub-severe as proximity to the mid-level ridge will foster insufficient deep-layer shear. Daytime Thursday, short range ensembles suggest the warming trend will continue as the mid-level ridge inches eastward. 850-mb temperatures are expected to warm by 2-3C owing to strong subsidence under the ridge, which will translate to afternoon highs in the low 90s to near 100. Another round of showers and thunderstorms is possible during the late afternoon into the overnight hours favoring the northwest and northern zones as a weak mid-level vorticity max ejects from the Rockies onto the central plains, with HREF probability of QPF > 0.01" in the 30-50% range. Similar to Wednesday, weak flow aloft will limit severe potential, however, the ejecting perturbation may support just enough H5 flow to result in some degree of storm organization, and a brief marginally severe wind gust or hailstone cannot be ruled out. Friday through the weekend and into early next week, medium range ensembles agree the mid-level ridge will stay mostly stationary while expanding. This pattern will lead to a continuation of the hot and mostly dry conditions across southwest KS, with Saturday currently appearing to be the hottest with afternoon highs in the 100-105 range. It is not impossible that a few stray showers and/or thunderstorms propagate through the northwest to northern zones during this time period as LREF probability of QPF > 0.01" is in the 10-30% range, but strong subsidence under the mid-level ridge will yield very spotty coverage, and the dry forecast (<15% pops) was maintained. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 509 PM CDT Wed Aug 21 2024 Good flying weather will continue through this TAF period, with VFR persisting and scattered cirrus. Many models do not develop scattered thunderstorms near HYS overnight through Thursday morning, so opted to keep the HYS TAF dry for now. Light southeast winds will continue to prevail at 9-14 kts. After 15z Thu, SE wind gusts of 20-25 kts are expected at all airports. && .DDC WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Springer AVIATION...Turner
Area Forecast Discussion
National Weather Service Des Moines IA
649 PM CDT Wed Aug 21 2024 ...Updated for the 00z Aviation Discussion... .KEY MESSAGES... - Mainly dry through Thursday, with low chance for rain/weak storms Friday morning northwest - Additional chances for showers and storms this weekend - Warmer temperatures arriving this weekend into early next week, especially Sunday/Monday && .DISCUSSION... Issued at 237 PM CDT Wed Aug 21 2024 Outside of the lingering light rain showers this morning that have since diminished, the overall weather pattern has changed very little, with surface analysis showing the large area of high pressure remaining over the Upper Midwest, while a weak low pressure system sits over Wyoming and Montana. Following the drying conditions, cloud cover has also been decreasing, with the majority of any remaining clouds over western Iowa while the remainder of the state sees broken areas of upper level clouds in an otherwise mostly sunny sky. Surface southeast flow has remained light, with some gusts around 15 mph but overall fairly comfortable this afternoon as temperatures sit in the upper 60s to low 70s. With increased sunshine and low level southwest flow, temperatures will continue to increase with highs reaching into the upper 70s. Upper level ridging across the western CONUS will continue to slowly track eastward over the next several days, though several waves riding the ridge look to move into the Central Plains during this time, which could lead to periods of showers and possibly some storms. The first is a shortwave and associated surface boundary extending into the Dakotas and Nebraska tracking east/northeast into the region late this evening into Thursday, though the general consensus among models is a weakening trend as it nears Iowa, mainly due to limited forcing and low level dry air as seen per model soundings. This will lead to continued dry conditions throughout Thursday, with breezy southeast winds and highs once again reaching into the upper 70s to low 80s into the afternoon. Another wave approaching Iowa into Friday morning from the Intermountain West looks to hold a somewhat better potential for showers and possibly a few weak storms. Even so, similar trends with less favorable forcing and lingering low level dry air per soundings from the HRRR, RAP and GFS, despite the more saturated profile per the NAM are more looking more likely to occur at this time, so the overall chances are rather low. Coverage over Iowa also varies among models as a result of these differences, though most generally keep much of the activity over the northwest half of the state, with fairly low-end rain amounts. Into the weekend, the thermal ridge will move over the Central Plains, which will send much warmer temperatures over the area into early next week. Temperatures in the 20s at the 850mb level with mostly clear skies Sunday into Monday will likely allow for favorable mixing to lead to surface temperatures reaching into the 90s, along with slightly breezy conditions. Increased instability with additional waves passing through look to bring additional chances for showers and storms both Saturday and Sunday, though timing and placement is more uncertain given timing ahead of this activity, so will be keeping an eye on it over the next several forecast cycles. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 630 PM CDT Wed Aug 21 2024 VFR conditions are expected to continue through the TAF period. High clouds increase especially west overnight into Thursday, but will generally be of little impact. Winds out of the southeast remain lighter overnight but turn more southerly and increase through the afternoon hours Thursday, the highest gusts in the northwest with gusts of 20-25 knots. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Bury AVIATION...KCM
Area Forecast Discussion
National Weather Service Gray ME
1024 PM EDT Wed Aug 21 2024 .SYNOPSIS... An upper low slowly moves eastward tonight continuing showers that may become heavy at times. Localized flooding is possible, especially in the higher terrain. The recent cool and unsettled pattern will continue through Thursday before the stubborn low pressure system slowly lifts out of the region with a drying and warming trend expected through the weekend. A cold front will usher in a return to somewhat cooler weather early next week along with a few showers and thunderstorms. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... Update... Have updated pops based on current radar imagery and latest HRRR. Showers will continue exit central areas and become situated over the mountains for the remainder of the night. Patchy fog to develop with some drizzle remaining possible as well. Otherwise, very little in the way of changes to the near term portion of the forecast. Prev Disc...The focus of the precipitation continues to be over the north and mountains. However, latest radar imagery at 2230Z was depicting slow moving showers over Cumberland, western Androscoggin and eastern Oxford Counties. This precipitation will likely train over the same areas late this evening leading to locally heavy precipitation. The HRRR continues to indicate heavy precipitation in the mountains this evening as well. Will continue to monitor trends this evening. Otherwise, only minor modifications to the near term portion of the forecast for temperatures, dew points and cloud cover. Prev Disc... Impacts: * Showers that may be heavy at times will develop tonight and my lead to localized flooding, especially in the higher terrain. Flash Flooding is not expected. Latest RAP13 analysis shows the center of the upper low has very slowly shifted eastward as expected, now over the Vermont- New York border. We continue to see daytime instability help blossom showers across the area. They will continue to rotate through the area this evening as the upper low continues its journey eastward. As always when upper lows are moving overhead, you have to worry about showers near the pivot point as they tend to train over areas. PWATs are less than inch and latest CAMs are keeping these storms progressive so Flash Flooding is not expected, but should training occur some localized flooding is possible, especially in areas of higher terrain where runoff contributes. SPC mesoanalysis currently analyzes around 250 J/kg across central and southern New Hampshire, so while no lightning has been observed thus far it is not out of the question before this shower activity is through. With that being said this activity should begin to taper off not long after midnight, leaving us dry overnight. Thinning clouds, and already cool daytime temperatures, will make for a chilly night with lows in the low 50s across the area, with some areas of the mountains and river valleys dropping into the upper 40s. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/... Impacts: * No significant weather impacts expected. Stacked low pressure moves overhead tomorrow which will create a set up very similar to what we saw Wednesday. Thinning of the cloud deck overnight will allow many places to start dry, but this will contribute to building instability heading into the afternoon, helping showers blossom heading into the afternoon. With the best forcing moving out of the area, coverage and instability will be less than today. Latest CAMs still show areas of 100-200 J/kg of CAPE being achieved which would be enough to develop an isolated thunderstorm. These showers will be light, briefly heavier in a thunderstorm, so no hydro issues are expected. High temperatures remain cool with highs in the upper 60s to low 70s south of the mountains, and low 60s to the north. As the upper low departs overnight, we will see clearing skies which will allow for another chilly night in the low to mid-50s for the area. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... High Impact Weather Potential: The potential for widespread high impact weather is low through the long term forecast period. --Pattern and Summary-- The primary change to the longwave pattern through the long term portion of the forecast is reduction of blocking across the central/eastern Pacific which will allow for an increasing Pacific influence across much of North American next week with as the EPO shifts positive. Closer to home...the period will open with a cutoff low overhead /though slowly lifting away/ with good agreement that another trough will take it/s place by the beginning of next week. Beyond this...by the middle and latter portions of next week...more substantial height rises reach the northeastern United States likely moving temperatures again above normal. A warming trend will open the forecast period through this weekend...before temperatures settle back early next week with the arrival of the next upper low. As for precipitation chances... building heights to begin the period should bring an end to the recent showery pattern with dry conditions through the weekend. Shower chances increase again early next week as the next upper low arrives...though the forcing suggests little support for widespread significant rainfall. Some slow moving...local downpours will be possible in the vicinity of the upper low. --Daily Details-- Friday through Sunday: Upper low lifts away from the region Friday with building heights and warming temperatures. Surface high crests south of the region on Saturday with a mid level shortwave ridge overhead. By Sunday...the low/mid level flow begins to back ahead of next approaching shortwave and associated trough diving towards the region from Quebec. This should allow for a dry weekend across the region with temperatures building from Friday into Saturday with T8s around 10C Friday warming to +13-14C through the weekend. This will result in highs building into the 70s Friday...with mid 70s to lower 80s from north to south for Saturday-Sunday. There will be more clouds on Sunday than Friday-Saturday with the approaching trough with moisture increasing /PWATs reach 1"/. Outside of some morning valley fog...no significant sensible weather is expected. Monday through Wednesday: Conditions will turn more unsettled for the beginning of next week with a cold front crossing the area Sunday night before the arriving shortwave closes off overhead. The upper pattern will be similar to what we/ve experienced this week...though temperatures aloft will be warmer. Thus...expect daily shower chances...with some rumbles of thunder given modest instability. The best threat of impactful weather will come from slow moving showers/storms, but this threat is expected to be isolated. Current consensus high temperatures are in the mid 70s to lower 80s. Could see these trend lower /at least for a day or two/ depending on the details of cloud cover/shower activity as well as the exact placement of the upper low...so kept the forecast a bit below the National Blend of Models. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... Short Term...Light rain showers are bringing varying VFR/MVFR decks late this afternoon, and will continue through early tonight. Lightning is not out of the question, particularly at CON, MHT, and PSM. While most terminals head toward VFR, LEB, HIE, and possibly AUG and RKD may be heading toward IFR/LIFR with fog developing. Either way, VFR will be the prevailing condition on Thursday. Westerly winds are expected to remain light. Long Term...VFR conditions are expected to dominate the long term period through Sunday. Morning fog will be possible at HIE/LEB. A cold front will drop through the region Sunday night with scattered showers which will bring some localized MVFR restrictions. Winds are expected to remain light through the period. && .MARINE... Short Term...No significant systems will be moving over the waters over the next 48 hours so conditions will remain below SCA criteria. Winds will remain generally westerly, with an afternoon seabreeze likely tomorrow afternoon. Wind gusts will be 10-15 kts. Long Term...Winds and waves are expected to remain below SCA levels through the long term forecast period. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR/SHORT TERM...Cannon LONG TERM...Arnott
Area Forecast Discussion...UPDATED
National Weather Service Indianapolis IN
732 PM EDT Wed Aug 21 2024 .KEY MESSAGES... - Dry with well-below normal temperatures and lower humidity - Temperatures trending warmer with above average temperatures by Saturday. && .FORECAST UPDATE... Issued at 732 PM EDT Wed Aug 21 2024 Previous forecast looks good and no major changes needed. 10th percentile model blend temperatures were used, and our only adjustment was to steepen the curve during the late evening and early tonight, since the air mass supported a quick drop last evening. Otherwise, satellite shows some smoke from wildfires in Canada that aren`t represented in HRRR or RAP smoke modeling. Limited sensible weather impact, but may scatter sunlight at sunset some causing a redish color and slightly more white color to the sky. && .SHORT TERM (This evening through Thursday)... Issued at 244 PM EDT Wed Aug 21 2024 Fall-like weather will continue for the short term as central Indiana remains under the influence of Canadian high pressure. Latest IND ACARs sounding shows a very dry atmospheric profile with a subsidence inversion around 850mb/1km agl. With 850mb temps well below normal for this time of year at 7C, max surface temperatures are only reaching the lower to mid 70s even with steep boundary layer lapse rates. Lowered afternoon humidity levels for today and tomorrow as deep mixing has already resulted in dew points in the 40s for most locations. Despite lower humidity, conditions are not meeting critical thresholds for fire weather concerns. Tonight will likely be the coolest night of the season for a few areas, especially low lying wind sheltered locations. Optimal conditions expected for radiational cooling as the center of the high pressure moves over the northern half of the state tonight. With such a dry airmass, light winds, and clear skies, decided to go well below guidance for min temps, towards the NBM10th percentile, with mid to upper 40s for Central and North Central Indiana and low 50s for South Central Indiana. Almost a copy/paste forecast for Thursday as the area of high pressure slowly begins to shift eastward. Highs may be a degree or two warmer during the afternoon in the mid to maybe upper 70s, but overall expect another dry, Fall-like day. && .LONG TERM (Thursday night through Wednesday)... Issued at 244 PM EDT Wed Aug 21 2024 Thursday Night Through Sunday. The stagnant weather pattern that has been in place for much of the week will continue late this week into the weekend as a broad and expansive ridge across the central US states is bookended by two larger low pressure systems off each coast. The system on the west coast will move into southern Canada with the ridge blocking most of the eastward progression. There will be a low potential for diurnally driven showers this weekend but soundings show a robust cap in place along with fairly low instability and no lifting mechanisms in place. As the ridge builds, temperatures will gradually continue to warm, especially as the northerly flow gets cut off by late Wednesday. Expect to see highs in the mid 80s by Friday followed by 90 towards Sunday. Monday Through Wednesday The ridge will slowly begin to migrate eastwards towards early next week which will keep the flow near the surface and aloft quite stagnant and lead to temperatures climbing into the low to potentially mid 90s by mid-week. A weak cold front may push through Tuesday into Wednesday, but the forcing associated with this system will be centered in Canada with only weak forcing towards the Ohio Valley. Ensembles show quite a bit of difference on both the timing and extent of precipitation, so plan on keeping POPs low until better agreement on the system progression arrives. By early next week, air quality may start to become a greater concern late this weekend into early next week with the aforementioned stagnant airmass and cap aloft leading to poor air circulation and a buildup of ozone. Forecast dewpoints look a bit aggressive in the models with the recent dryness combined with the corn sweat season coming to an end, so plan on tapering those down a bit to limit the afternoon heat indices and associated heat risk. && .AVIATION (00Z TAF Issuance)... Issued at 632 PM EDT Wed Aug 21 2024 Impacts: - None Discussion: VFR conditions will prevail. Thursday morning, a slight veering of wind direction to more east-southeasterly is anticipated, but wind speeds will remain light. Some smoke from Canadian wildfires is evident on satellite but should be minimally noticable and not impactful, relegated to the upper atmosphere. Some cumulus may again form Thursday late morning onward. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...BRB SHORT TERM...CM LONG TERM...White AVIATION...BRB
Area Forecast Discussion
National Weather Service Marquette MI
729 PM EDT Wed Aug 21 2024 .KEY MESSAGES... - Mostly dry forecast into next week. - Near normal temperatures round out the work week before above/much above normal temperatures return for the weekend into next week. - Best rain chances (20-40%) over the next 7 days will be late Thursday night into Friday. && .SHORT TERM /THROUGH THURSDAY/... Issued at 129 PM EDT Wed Aug 21 2024 GOES-16 Visible imagery shows some fair weather cu over the central and eastern portions of the UP as well as some lower marine clouds over western Lake Superior. Apparent on satellite and in the clear air clutter on KMQT radar reflectivity is the Lake Superior lake breeze, with CAMs resolving that lake breeze pushing inland along with one off of Lake Michigan this afternoon. RAP analysis shows a closed upper high over the New Mexico/Texas border with a ridge axis extending NE from there all the way into northwestern Ontario. With the peak of negative vorticity advection over the Upper Great Lakes today, the surface feature response is a ~1025mb high pressure and pleasant weather. Expect high temperatures in the low to mid 70s today, slightly below normal. Overnight, expect another clear night with temperatures falling below normal and into the 40s. As temperatures will have a bit farther to fall tonight than previous nights, temperatures shouldn`t hit freezing like they have in at least one location the past couple nights. However, given the various microclimates, wouldn`t be surprised if a typical cold spot hits the upper to mid 30s tonight. Patchy fog is once again possible tonight, with chances for 1/2SM or less fog highest in the east (20-40%) with ~10-20% chances elsewhere. Thursday, the ridge axis will move directly overhead and the surface high will shift east to be over the southern portion of the Great Lakes Basin. Weaker subsidence aloft will allow for even more diurnal cu to form over the central and western UP, though virtually every model available shows 0 precip except for the 00Z and 12Z NSSLWRFs. Will keep 0 PoPs in the forecast until at least some other model support comes for daytime showers. The gradual warming trend will continue, with highs firmly in the mid to upper 70s with a few typical warm spots ~40% likely to break 80. CAMs also show lake breezes off the Great Lakes. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... Issued at 348 PM EDT Wed Aug 21 2024 The tranquil weather over the UP will be disturbed by a weak ridge- riding shortwave that will arrive over western Lake Superior by 00Z Friday. LREF mean SBCAPE is around 100-200 J/kg, which is not terribly impressive but is enough that thunder cannot be ruled out of the forecast (~15%). While the arrival of showers is just barely within the valid times of the HREF suite of CAMs, there are some disagreements about the coverage of showers, ranging from isolated- to-scattered (WRF FV3) to broad coverage (NAM Nest). With around 1.25 inches of PWAT available, a localized downpour cannot be ruled out as maximum HREF precipitation peaks at 0.5-1.0 inch, but the mean (and more likely) values are 0.01 to 0.25 inches. Some gustier winds might be realized with this system as Euro ensemble mean wind gusts on Friday are around 25 mph. Despite the cloud cover from this shortwave inhibiting radiational warming, warmer air will be advecting in, keeping highs on Friday near normal in the mid- to upper-70s and locally near 80. Following the passage of showers on Friday, the pattern beyond looks dry, with mean LREF accumulated precipitation by next Wednesday evening only around 0.5-1 inch. An anomalously low trough digging in over the West Coast will help kick ridging further east, and with the GEFS showing 500mb height anomalies exceeding +15 dam by 06Z Monday, the UP will be in for warmer than normal temperatures. The NBM shows widespread mid-80s with around 10% chances of some interior UP locations exceeding 90 degrees early next week. Conventional wisdom would indicate that a trough passing through the Rockies should help kick a low pressure towards the UP, but the 12Z GEFS really struggles to bring low pressure to the Upper Great Lakes, favoring a weak surface high instead. While some occasional diurnal showers cannot be ruled out, this forecast will lean slightly drier than the NBM. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 728 PM EDT Wed Aug 21 2024 Much like the past few nights, high pressure over the Great Lakes continue VFR conditions through the TAF period except for periods of patchy FG before sunrise. Confidence is low on timing and coverage, especially at CMX, thus opted to give IWD and SAW a TEMPO for possible visibility drops between 06z-11z. Once day breaks and fog clears, not looking at any forecast concerns for the rest of the day. Winds will be light and southerly, poking a bit higher at IWD with gusts 10-15 kts. && .MARINE... Issued at 348 PM EDT Wed Aug 21 2024 High pressure over the Great Lakes will keep wind gusts below 20 kt through Thursday night. As a weak shortwave pushes over Lake Superior late Thursday night through Friday, southwest wind gusts increase to 20-25 kt between Isle Royale and the Keweenaw Peninsula on Friday. With general broad ridging to return over the Great Lakes, wind gusts are expected to remain below 20 kt Saturday through the end of the forecast period. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...GS LONG TERM...GS AVIATION...BW MARINE...GS
Area Forecast Discussion
National Weather Service San Angelo TX
618 PM CDT Wed Aug 21 2024 ...New AVIATION... .SHORT TERM... (This evening through Thursday) Issued at 156 PM CDT Wed Aug 21 2024 Suffice it to say this week continues to be the hottest week of the summer for West Central Texas. As of the 2 PM hour both San Angelo and Abilene have already broken their record highs for the day, with the monthly record well within reach (111 degrees at both locations set in 2023). The upper level high pressure ridge will remain over the region tomorrow. This will result in another day of excessive heat, with highs very similar to what we are experiencing this afternoon. Thus have extended the excessive heat warning and heat advisory through Thursday evening. The one thing of note for tomorrow is a couple of the convective allowing models such as the HRRR show some isolated showers or storms developing in the late afternoon and evening hours. Given the strength of the upper ridge overhead confidence is low in this scenario. Have kept mentionable PoPs out of this forecast package but a slight chance of PoPs may need to be added in subsequent forecasts. Coverage would likely remain low but any storm that does develop would have the potential to produce strong downburst winds. Otherwise, the very hot and dry conditions will persist. && .LONG TERM... (Thursday night through next Wednesday) Issued at 310 PM CDT Wed Aug 21 2024 Gusty south winds will be possible Thursday night, mainly across our central and northern counties. With development of a low-level jet, one of the hi-res models indicate a potential for gusts over 25 mph in the overnight hours. This setup could keep low temperatures above 80 degrees across some of the Big Country and Concho Valley, and limit lows 77-79 degrees elsewhere. The strong upper level high will shift northeast over the Red River Valley on Friday. Highs on Friday won`t be quite as hot in our area, but will still be in the Heat Advisory range (105-108 degrees) for most if not all of the Big Country and Concho Valley. Our Heartland and southern counties will have highs in the 100-103 range. The upper high will continue shifting northeast across Oklahoma Saturday, and into eastern Kansas and western Missouri Sunday. With With an extension southwest across West Texas, this high is expected to remain our dominant weather influence through the weekend. With gradual weakening of the 850mb thermal ridge, at least temperatures will not be as hot, but will remain above normal. Expect highs Saturday and Sunday to range from 100-104 in most of the Big Country and Concho Valley, to the mid and upper 90s in our southern counties. A forecast change in the upper level pattern next week is expected to result in temperatures trending at least a little cooler in our area, and some rain chances. An inverted trough is progged to move from the northern Gulf of Mexico west into South Texas on Monday. Medium range models differ on the subsequent track of the system Tuesday and Wednesday, with potential for it to linger over south- central Texas or move northwest up the Rio Grande Valley toward the Big Bend area. This has implications on the potential extent of rain chances and cloud cover for our area, and on the extent of the cooling trend with temperatures. At this time, we have a low chance (20 percent) for showers and thunderstorms in some of our southern and southeastern counties Tuesday afternoon, and across much of the southern half of our area Wednesday afternoon. At this point, we have forecast highs Tuesday/Wednesday generally ranging from the mid 90s in our southern counties, to the upper 90s to 101 in the Concho Valley and Big Country. && .AVIATION... (00Z TAFS) Issued at 615 PM CDT Wed Aug 21 2024 VFR conditions are expected for the next 24 hours. We have a few showers and thunderstorms around our area this evening, however impacts are not expected at any of our TAF sites. Storms should continue south and eventually weaken by sunset. Isolated storms could develop tomorrow late afternoon as well, but confidence is too low to include them in this TAF package. && .PRELIMINARY POINT TEMPS/POPS... Abilene 79 109 82 107 / 0 10 10 10 San Angelo 80 109 80 106 / 0 0 10 10 Junction 77 107 77 101 / 10 10 10 10 Brownwood 77 108 78 103 / 10 10 10 10 Sweetwater 80 111 82 108 / 0 0 0 10 Ozona 76 103 77 101 / 0 0 0 10 Brady 77 106 78 102 / 10 10 10 10 && .SJT WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning until 9 PM CDT Thursday for Brown- Callahan-Coke-Coleman-Concho-Fisher-Haskell-Irion-Jones- McCulloch-Nolan-Runnels-San Saba-Shackelford-Sterling-Taylor- Throckmorton-Tom Green. Heat Advisory until 9 PM CDT Thursday for Crockett-Kimble-Mason- Menard-Schleicher-Sutton. && $$ SHORT TERM...42 LONG TERM....19 AVIATION...AP
Area Forecast Discussion
National Weather Service Topeka KS
623 PM CDT Wed Aug 21 2024 .KEY MESSAGES... - There are small chances for showers and thunderstorms early Thursday and Friday mornings; otherwise mainly dry weather is expected to hold through early next week. - One more day of slightly below average temperatures Thursday before a warm-up is forecast into the weekend. && .DISCUSSION... Issued at 244 PM CDT Wed Aug 21 2024 The forecast area remains under the influence of expansive sfc high pressure centered over the Great Lakes and upper Mississippi River valley. The upper levels consist of a ridge over TX/NM in between troughing over New England and the British Columbia coast. As such, southeasterly winds on the southwest periphery of the sfc high continue to keep cooler and drier air in the area. Afternoon temperatures are still expected to top out in the 80s with dew points in the 60s. Heading into tonight and Thursday, a weak perturbation on the northern periphery of the upper ridge along with upslope flow should help to develop convection off the High Plains. This is progged to move eastward across KS through the overnight hours, but it will be moving into a more stable environment as it does so. Additionally, forecast soundings in north central KS don`t show a lot of moisture through the column. Some CAM guidance does show rain making it into western portions of the area during the predawn hours before dissipating later in the morning, but am overall unimpressed with the limited instability and moisture in place. As such, have held onto PoPs in case there is enough ascent from isentropic lift and any remnant MCV, but have limited them to 25% or less. Perhaps of note is that the new 18Z HRRR has slowed down this activity compared to 12Z model runs, so it`s possible the rain may just come later in the morning than previously anticipated. Once the morning wave moves off, another perturbation aloft is progged to develop another round of scattered showers and storms late Thursday, moving northeast into Friday morning. Again there doesn`t appear to be as much instability this far east, though there could still be enough isentropic lift to produce precipitation. Still, rain chances are favored more north and west of the area with the wave moving northeastward, so have limited PoPs to 20% or less in the western counties between 06-12Z Friday. Meanwhile, the upper trough near British Columbia will have been amplifying and digging along the western US. This should help the upper ridge to expand northward, increasing mid-level heights over the area and bringing a thermal axis overhead into Saturday as well as increasing low-level moisture. Saturday currently looks like the hottest day of the upcoming week, with highs in the mid 90s to low 100s. Will continue to monitor trends for the next few days, but if the current forecast holds, a Heat Advisory may be needed particularly for southern portions of the area. Sunday is a little less certain as heat indices around 105 look less widespread and more brief, but it will still be hot with highs around 100. By Monday, the main upper trough looks to deamplify and push a weak cold front through the region into the evening. Deterministic models are showing some precipitation associated with this, but the better upper support may be well north of the area depending on how strong the trough remains. At the very least, this should help to flatten the upper ridge and bring temperatures down a bit into the next work week. Highs are forecast in the 90s, which is still above average but not as hot as this weekend. Rain chances look quite low given the uncertainties in the troughing pattern. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 620 PM CDT Wed Aug 21 2024 VFR prevails tonight and Thursday. Winds turn more easterly tonight and decrease below 10 kts. A slight increase is then expected again after sunrise Thursday. A few showers may approach KMHK Thursday morning, but chances remain low, around 15 percent. && .TOP WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Picha AVIATION...Teefey