Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/22/20

Area Forecast Discussion
National Weather Service La Crosse WI
651 PM CDT Sun Jun 21 2020 .SHORT TERM...(This evening through Monday) Issued at 305 PM CDT Sun Jun 21 2020 Atmosphere is primed and ready to go for isolated to scattered convection this afternoon as temperatures climb through the low to mid 80s across much of the area. Ongoing weak moisture transport continues to nudge dewpoints upward through the 60s, promoting MLCAPEs of 1000-2000 J/kg. Only limiting factor for more widespread convection thus far has been a lack of robust forcing. A decaying MCV passing through central IA did manage to trigger a few brief vigorous updrafts just south of our area. Otherwise there is a very weak H5 ripple that appears to be the mechanism responsible for some scattered pulse convection across far northeast Iowa into far southwest Wisconsin. Updraft development has been quick and robust, but in the absence of any substantial deep layer shear they have been unable to sustain themselves for long. Stronger cells this afternoon will be capable of producing small hail and gusty winds (perhaps marginally severe with a storm or two) as well as localized downpours. In this weakly forced environment, CAMs are having a hard time pinning down this pulse convection, but would expect it to remain focused mainly near and west of the Mississippi River where low level lapse rates are steepest. Seeing some agitated cu fields across portion of southeast MN and west-central WI. Main focus for stronger storms will be this evening as a stronger mid-level shortwave rolls into the area ahead of a cold front. Low level convergence associated with these features is already promoting development of a linear complex of storms from southwest MN into northwest WI. Juicy summerlike airmass out ahead of this line will fuel the storms as they slowly approach our area towards evening. CAMs show some general agreement with timing and evolution, but there`s still enough spread to muddy the waters. Latest HRRR might be lagging a bit behind current convective development, but it pinpoints the line of storms entering our CWA from the northwest around 7 PM with gradual eastward progression across the rest of the area through roughly 1 AM. CAMs continue to favor a stronger southern tail to this line of convection that is progged to dive just to our south where nose of low level moisture transport will be focused over central/southern IA. So the question is how the northern portion of this convective line will evolve as it crosses our CWA, where forcing and instability aren`t as favorable. Most CAMs show a break/gap in the line as it crosses our area. The line of convection will be arriving as instability is diminishing across our area, so our far western counties (grazed by SPC`s slight risk) will see the greatest chance of any strong to severe activity. Soundings would support some gusty winds and perhaps isolated marginally severe hail. But again, deep layer shear will be meager so not expecting long-lived, sustained stronger storms. Localized heavy rainfall certainly a possibility with this tropical-like humid environment: PWATs >1.5", deepening warm cloud depths, and slow- moving storm progression. Northeast IA into far southwest WI will be the area of greatest concern, especially if southern flank of storms would begin to repeat along the outflow. Earlier HRRR runs suggested this possibility but now look a little more progressive. Something to watch, though. HREF mean QPF suggests 0.5 to 1.5" with max QPF on the order of locally 2 to 3+". Moisture transport will nose into our southeast late tonight, which may steer the weakening southern tail of convection into our south/east counties. While storm activity will be diminishing, there will likely be a more stratiform band of lingering rain continuing to progress through our east into Monday morning ahead of the approaching cold front. That front will drop in from the northwest just after daybreak and may trigger some additional isolated activity mainly across our southeast once it recovers from lingering morning showers. Less instability in place than today, but steep low level lapse rates may support a stronger storm or two. .LONG TERM...(Monday night through Sunday) Issued at 305 PM CDT Sun Jun 21 2020 Northwest flow aloft will dominate through mid-week as an amplified upper trough spins across the Great Lakes region. Despite a relatively dry, seasonable airmass, surface heating beneath cold mid- level temps will likely generate some scattered mainly diurnal showers/storms as weak upper waves rotate through the flow. By late in the week, the upper trough gets kicked east with the flow becoming more zonal. There is broad model agreement for a shortwave trough to slide through on Friday with a chance for storms as low- level moisture/instability increase. For next weekend, expect warmer highs in the 80s. With the progressive zonal flow pattern, some potential for periodic storms continues depending on timing of low predictability shortwave troughs. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 651 PM CDT Sun Jun 21 2020 Broken line of storms moving into RST at this hour and will make it into LSE around 02Z. These storms have largely been sub-severe but there will be an brief period of gusty winds out of the west to northwest as the storms blow through. Upstream obs have generally remained VFR despite the downpours, but cannot rule out a dip to MVFR or perhaps briefly IFR. Otherwise these storms have produced a decent amount of lightning and isolated small hail. Once they blow through there will be some lingering showers. Later tonight and perhaps into Monday morning may bring another round of showers and perhaps a storm to mainly LSE. Otherwise expect lowering MVFR ceilings towards daybreak as a cold front approaches. Should see a return to VFR around midday. Light and variable winds later tonight will quickly swing around to the north-northwest by late morning once the front drops through. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Kurz LONG TERM...JM AVIATION...Kurz
Area Forecast Discussion
National Weather Service Boston/Norton MA
1029 PM EDT Sun Jun 21 2020 .SYNOPSIS... Summer heat and humidity continues! We continue to expect above normal temperatures for the start of the work week. Similar to this weekend, isolated afternoon showers or thunderstorms are expected. A cold front passes through the area during late Wednesday into early Thursday, which may bring a better chance for some rainfall. Warmth continues during Friday into the weekend, but with noticeably lower humidity. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... 1015 PM Update... Forecast is largely on track so made minimal changes. Notice two areas of low clouds/fog, one along the Cape and Islands and another area just north of Cape Ann coming down from coastal Maine. WPC surface analysis shows a very weak pressure gradient across our area, with winds north of the Rte 2 corridor generally northeasterly and the winds south of Rte 2 having a southerly component to it. Nonetheless, very light winds. Will keep an eye on potential fog development along the immediate South Coast and the Cape and Islands like the past few nights. Also would monitor low clouds/fog development along the Eastern MA coast, especially Cape Ann. Interior fog prone areas such as in the river valleys could also see some patchy fog. Otherwise, a mostly dry, muggy and warm night with lows in the 60s. PREVIOUS DISCUSSION... 7 PM Update... We`re done with the thunderstorms for this evening, as the seabreeze that helped to kick off some slow moving storms earlier this afternoon has progressed into central MA/dissipated. Mesoanalysis shows the boundary moving out of the region of greatest sfc based CAPE (eastern MA) while convective inhibition has increased in the last hour as well with loss of diurnal heating. The main change with this evening`s update was to add in a chance of a few pop up showers overnight near/after midnight for generally areas from Worcester eastward. Another hot & humid day across much of Southern New England as many locations recorded temperatures in the upper 80s and low 90s. We continue to monitor BOX radar for pulse showers and thunderstorms during the remainder of Sunday afternoon. We`ve seen much of the convection to the north in New Hampshire and Vermont, and as of 415 pm thunderstorms had developed along the eastern MA sea breeze boundary. Across southern New England the MUCAPE is 1000 to 2000 J/kg, greatest in the vicinity of the sea breeze boundary, thus pop-up showers or thunderstorms remain possible until we near sunset. Additionally with the daytime heating and elevation of the Berkshires, like on Saturday, the Berks could see a pop-up storm or two. Coverage of these will not be widespread so not a washout for most locales, a few localized spots may receive a quick inch of rainfall. Tonight: HREF continues to support the resurgence of low-level clouds night across Rhode Island and southeast Massachusetts. As in nights previous the fog bank will return as well to coastal RI, southeast MA, and the valleys across northwestern MA. It`s another warm and muggy night with lows in the 60s. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... A coastal low pressure will pass to the southeast of the Cape and Islands on Monday. While no significant rain is expected from this, a very brief shower or two could reach eastern Cape Cod or Nantucket during the mornings hours. The strong summer sun will once again burn off the morning clouds at the coast, before returning to another mostly sunny afternoon. Yes, it will be another hot and humid day. Especially away from the coast temperatures could once again reach the upper 80s and low 90s. We are expecting slightly `cooler` temperatures in and around Boston in the low and mid 80s because of the sea breeze. Dewpoints once again will be in the mid and upper 60s. A mostly dry day is on tap, but like the past couple of days we do have the threat for pop-up showers or a thunderstorm. PWATs values are in the neighborhood of 1.50", a brief downpour under these pulse storms are possible. Many members, including the HRRR favor the development of these pulse showers as far east as Rhode Island and central Massachusetts. You guessed it! Monday night into Tuesday is once again mild and muggy! A/C will be your best bet for a comfortable night sleep! Like clockwork, coastal fog and low-level clouds will move back into the coastal region of RI and SE MA by Tuesday morning. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Highlights... * Very warm and humid conditions continue thru Wednesday, with isolated storms near the terrain on Tuesday. * Cold front late Wednesday/early Thursday brings better chances for showers and storms, though timing is still unclear. * Still warm Friday into the weekend but with noticeably lower humidity levels. Details... The weather pattern on Tuesday remains remarkably similar to the last several days as we remain downstream of an upper low over Ontario. Under the warm and muggy airmass (dewpoints will be in the upper 60s) we should once again achieve several thousand J/kg of CAPE during the afternoon allowing for some isolated showers and thunderstorms mainly tied to the terrain. Again expecting quick pulse storms given zero bulk effective shear. Difference from Monday may be a lesser chance of showers over eastern/southeastern MA and RI as brief mid level ridging provides more subsidence to keep those areas dry. The best potential for widespread rain/thunderstorms comes Wednesday into Thursday. This is thanks to a pattern breakdown causing heights to fall as the sfc low moves north of New England, dragging its cold front through around Wednesday night/Thursday morning. The RRQ of a 100 kt upper jet moves overhead during the time period providing better synoptic lift for more widespread showers ahead of the front arrival. Still there remains some uncertainty on the timing of the front which will impact the potential for strong thunderstorms. At the moment it looks like some scattered thunderstorms are likely Wednesday afternoon and evening. Instability will be abundant, but wind fields are marginal; around 25-30 kts of 0-6 km bulk shear which would limit severe potential. Better shear comes in behind the front. By Thursday and Friday southern New England is under cyclonic flow with colder temps aloft, allowing for more instability showers and thunderstorms before our next front/more widespread chance of showers may come over the weekend. Temperatures through the long term will remain above average...moreso Tuesday and Wednesday in the upper 80s and 90s. Things cool down behind the front late in the week but we`ll remain in the upper 80s. Humidity will be elevated, but relatively lower Thu/Fri, in the mid 50s to mid 60s rather than upper 60s. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 0220Z Update... Tonight...moderate confidence. Low CIGs/VSBYs to MVFR/IFR expanding beyond ACK into south coastal RI/MA and Cape Cod by 06z. VFR elsewhere in the interior MA and CT terminals, with patchy MVFR/IFR vsbys in fog. There is a low probability of stratus along and offshore of coastal Maine dipping southward into the North Shore and vicinity of BOS. ESE wind around 10 kts expected 14Z Mon and on. Monday...high confidence. Any leftover MFR/IFR CIGs/VSBYs will quickly lift and dissipate, improving to VFR. Exception will be over immediate south coasts of MA/RI and Cape/Islands, where it may take longer in the morning to lift and dissipate. Low probability of stratus along far northeast MA early in the morning. Isolated to widely scattered SHRA/-TSRA during the afternoon. Monday night...high confidence. Mainly VFR, with IFR/LIFR stratus/fog redevelopment possible along south coastal MA/RI, the Cape and Islands. Also some IFR fog possible in river valleys. KBOS Terminal...High confidence in TAF, except moderate confidence late tonight and early Monday. There is a low probability of marine stratus to the N drifting S into BOS vicinity late tonight/early Mon. KBDL Terminal...High confidence in TAF. Outlook /Tuesday through Friday/... Tuesday through Tuesday Night: VFR. Slight chance SHRA, isolated TSRA. Wednesday: VFR. Breezy. Chance SHRA, chance TSRA. Wednesday Night: VFR. Breezy. Slight chance SHRA, isolated TSRA. Thursday: VFR. Chance SHRA, slight chance TSRA. Thursday Night: VFR. Slight chance SHRA, slight chance TSRA. Friday: VFR. Slight chance SHRA, isolated TSRA. && .MARINE... 1020PM Update... Tonight and Monday... An offshore, non-tropical low with a center located about 250 miles southeast of Nantucket will track northeastward during tonight and Monday. This system is passing far enough offshore to keep winds/seas below SCA thresholds for the southern New England coastal waters. Seas building to 2 to 4 feet on the outer coastal waters. S/SW winds 10 to 15 kts tonight and Monday, except winds becoming SE around 10 kts for Monday along east coastal MA and Cape Cod Bay. Areas of fog develop tonight, areas with visibility below 1 mile at times especially for the southern waters. Visibility improves during Monday morning, though patchy fog may linger during the day. Monday Night...Seas diminish to 2-3 ft as the offshore low pulls further away from our area. Winds become SW around 10 kts. Outlook /Tuesday through Friday/... Tuesday: Winds less than 25 kt. Slight chance of rain showers, isolated thunderstorms. Tuesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers, isolated thunderstorms. Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, chance of thunderstorms. Wednesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers, isolated thunderstorms. Thursday through Thursday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, slight chance of thunderstorms. Friday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...BW/Gaucher NEAR TERM...BW/Chai/Gaucher SHORT TERM...Gaucher LONG TERM...BW AVIATION...BW/NMB MARINE...BW/NMB
Area Forecast Discussion
National Weather Service Dodge City KS
624 PM CDT Sun Jun 21 2020 ...Updated Aviation Discussion... .SHORT TERM...(This afternoon through Monday) Issued at 113 PM CDT Sun Jun 21 2020 ...Significant Severe Weather Episode This Afternoon/Evening... WFO DDC is preparing for severe weather operations early this afternoon. Nearly full insolation has heated a very moist boundary layer through midday, with mesoanalysis of up to 6000 J/kg SBCAPE in SW KS. Shear has modestly improved, with effective bulk shear to near 35 kts. As NWly flow aloft increases this afternoon, and an embedded shortwave/associated forcing for ascent arrives, explosive thunderstorm development is expected. Convection will fire quickly across the northern zones by 3 pm. Have coordinated with SPC on the upgrade to moderate risk probability. HRRR has shown strong consistency with storms quickly organizing into a severe squall line, and then marching out of the SE zones around 10 pm. Damaging winds are likely with this squall line, with gusts of 60-70 mph common. Some gusts to near hurricane force may occur, given a linear configuration and tremendous CAPE axis. Large hail will be focused across the initial northern storms. That said, will be watching for discrete supercell development on the tail end of the squall line (tail end Charlie) or just ahead of the squall line. If a discrete supercell can be maintained through 5-7 pm, then giant hail and a tornado risk would occur. There is some CAM consensus that this threat would focus on the Dodge-Garden- Liberal triangle vicinity 5-7 pm. MCS will clear the SE zones by midnight, with all zones dry after midnight. There is some potential for another round of convection amid the continued NW flow aloft Monday afternoon/evening, but much of the atmosphere will be strongly worked over through tonight. As such, any thunderstorms Monday PM will likely favor the Oklahoma border region, where reasonable instability will have the best opportunity to reload. .LONG TERM...(Monday night through Sunday) Issued at 125 PM CDT Sun Jun 21 2020 Weak disturbances will continue to move down through the northwest flow aloft through at least the late part of the week. This will bring a chance of storms across portions of western Kansas in the late afternoon to evening hours. Otherwise expect partly cloudy skies and winds generally from a southerly direction. As for temperatures, highs will start out in the mid 80s Tuesday with low to mid 90s for the remainder of the long term period. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 605 PM CDT Sun Jun 21 2020 A line of strong to severe thunderstorms will cross in the Dodge City and Liberal areas through 02z Monday. Wind gusts in excess of 30 knots and reduced visibilities due to heavy rain will be possible for the next hour or two with these storms near these two locations. Ceilings will be as low as 3000ft AGL. Behind these storms ceilings will improve and an easterly wind will develop at 10 knots or less. Between 10z and 14z Monday some patchy fog and areas of ceilings in the 500ft to 1000ft AGL level will be possible across southwest Kansas. && .PRELIMINARY POINT TEMPS/POPS... DDC 62 88 60 85 / 50 20 30 10 GCK 61 88 60 85 / 80 20 30 20 EHA 62 92 61 84 / 20 40 50 30 LBL 63 91 61 86 / 30 30 50 10 HYS 61 86 59 84 / 80 20 20 10 P28 66 90 63 87 / 90 30 30 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Turner LONG TERM...Hovorka_42 AVIATION...Burgert
National Weather Service Kansas City/Pleasant Hill MO
620 PM CDT Sun Jun 21 2020 .Discussion... Issued at 231 PM CDT SUN JUN 21 2020 Today`s forecast became much more challenging with the formation of the convection along an isentropic surface over central KS this morning. This convection was not picked up in any guidance well and CAMs are still struggling with this development 6 hours later. The main impact of these storms was the massive cold pool and cirrus shield that has developed throughout the day. Central Nebraska was not able to get into the 90s which would have built a large MLCAPE or MUCAPE reservoir in that corridor. This has delayed convective initiation over this region and also shifted that development further west in KS and further north in Nebraska. A small ridge of MLCAPE was able to develop along the warm front over northeast Nebraska with convective initiation going on there right now as of 2PM. Western KS has also joined the party with severe storms quickly developing near a surging dryline. Going into the overnight hours the thoughts were that two main areas of storms would form in north central KS and NE, but the morning convection has altered that solution. Now it appears there will be three different regions of convection this afternoon, western KS, central KS, and northern NE. Due to the low level forcing mechanisms these storms will likely become multicellular and eventually linear as the cold pools start to develop. As the shortwave and surface features progress the MBE vectors will start to shift from westerly to northwesterly around sunset. So any MCSs that develop from these areas will start to take a more southeast direction, becoming even more southerly as the LLJ develops (if central KS storms don`t impede that) and LL winds shift more SW. Due to that nature of storm movement, our area would need an MCS to form up more over central NE for the KC Metro and eastern NE for northern Missouri. Based on the latest satellite and radar trends the central NE storms may not even happen, but the eastern NE storms look likely to be a player. If this does develop into a MCS then it would reach NW Missouri around midnight and push through central Missouri. What may hurt the chances of severe weather is that the cirrus blow off from the current storms in central KS has keep our MUCAPE availability lower than it would have and more confined to IA and right along our border. This may provide enough fuel to keep the MCS going, but it will likely weaken as it enters Missouri, but the LLJ may aid in a more balanced outflow boundary. We currently like the overall trend of the HRRR and RAP where a MCS moves through northern Missouri, but weakens over time. There is a real possibility the KC Metro and our western areas don`t see a rain drop, unless something can get going over central Nebraska before sunset if it can recover in time. A constant mesoanalysis will be necessary to keep the forecast accurate with timing and intensity tonight as things play out to our west and northwest. How everything plays out overnight tonight will have quite a bit of implications to Monday`s forecast. As stated above, the thought is that storms may not develop as robust as previously thought over central Nebraska which will possibly limit the MCS effects going into Monday morning. If that is the case, then there is a better chance of more substantial instability building into our area ahead of the cold front which will be over NW Missouri by noon. This would develop a corridor of potential convective development along and east of I-35 with 1000-2000 J/kg (all depends on MCS remnants or not) and effective shear of 35-40kts. Due to the strong synoptic forcing, storms would likely become linear quickly which would limit the large hail threat, but increase the damaging wind threat. If an MCS does push through Monday morning then that will delay our ability to heat up and build that instability. This may either cause the storms to develop later and further east, or stay capped and not develop at all. There is a lot of uncertainty in tomorrows forecast based on what happens this afternoon and overnight. Things become much less complicated Tuesday on the backside of the cold front with a cooler airmass moving into the region. Temperatures will be very comfortable for late June with highs in the upper 70s to lower 80s and dewpoints in the 50s! Wednesday continues the trend of cooler weather with highs slightly higher in the low to mid 80s. Wednesday night a LLJ over KS may develop some elevated showers and storms over eastern KS and western MO through the early morning timeframe. Unfortunately, our cool and dry pattern starts to break down on Thursday as southerly flow returns to the Central Plains ahead of an incoming shortwave trough over the Rockies. We`ll climb back into the 90s with dewpoints in the upper 60s to lower 70s which may also allow some pulse-like convection to occur over central Missouri in the afternoon. A cold front will develop ahead of the previously mentioned shortwave trough which may become the focus for storms late Friday afternoon into the evening over northern Missouri. Guidance starts to vary on how the front will progress into Saturday leaving some uncertainty for how wet or dry the weekend may be. NMB PoPs trend in the uncertain direction as well with 30-40 percent over much of the region. && .Aviation...(For the 00Z TAFS through 00Z Monday Evening) Issued at 616 PM CDT SUN JUN 21 2020 Could be a tricky aviation weather night. VFR conditions will continue through sunset, towards 06Z, expect scattered thunderstorms to move into portions of the region from the west. Introduced VCTS around this time, as coverage remains a question mark. Believe the best chance for storms will be in northeastern Kansas and northwestern Missouri, primarily effecting KSTJ, but cannot rule out activity farther south. Winds will begin to shift more westerly through sunrise and shower chances return midday, through the end of the period. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Discussion...Barham Aviation...Kurtz
National Weather Service Eureka CA
331 PM PDT Sun Jun 21 2020 .SYNOPSIS...The first full official week of summer will bring an extended stretch of hot, dry and sunny weather to interior northwest California, while cool onshore breezes and marine layer clouds keep most coastal areas seasonably cool. && .DISCUSSION...While the big story for the upcoming week will remain hot inland temperatures, most of the area is actually running several degrees cooler compared to this time yesterday. That still puts the warmest valley locations into the low 90s, but the deeper marine air has clearly taken the edge off. Persistent cloudiness socked in around the lower Eel River basin has made for a more dramatic change compared to yesterday for places. With the building ridge and warming temperatures aloft, along with light onshore flow in the boundary layer, it will be tough to get rid of the stratus and fog particularly around Humboldt Bay over the next couple of days. Still, have continued to advertise some afternoon clearing, even though in some lucky locations it will still be tough to come by, as we have seen Sunday afternoon. As far as the heat goes, little has changed with the overall forecast, message and impacts. That said, have swapped the Excessive Heat Watch for a Head Advisory. This was the best compromise for a unified message with our neighboring offices, and matches up well with the levels of heat risk that the bulk of our area is forecast to see. There will be some locations that will have a higher heat risk that could have been deserving of an excessive heat warning, like around Weaverville, Douglas City, and eastern Lake County where temps may reach 103 to 105...but the majority of our valleys will see more typical summer-time warmth in the mid 90s to low 100s. That said, do not take this heat for granted, especially if you haven`t acclimated yet this year or are from out of the area. The risk of heat related illnesses will be real during the peak afternoon hours. Try to spend more time in the shade, drink plenty of fluids, and take care care of your very young and elderly family members and neighbors. A mid week disturbance will bring a lull in the heat; limiting most interior valleys to the 90s on Wednesday. Friday and Saturday have the potential to be the hottest days of the entire forecast period as the ridge rebuilds and amplifies over our area, with 850 temps possibly reaching 27 to 30C and H5 heights in the low to mid 590s. Would not completely rule out a stray mountain thunderstorm over the Trinity Alps or Yolla Bollys on Wednesday afternoon, but for now have left out of the forecast. That gives us a dry next 7 or 8 days. /AAD && .AVIATION...By midday, remnant bands of the coastal stratus layer were continuing to stream over Coastal terminals with mostly MVFR ceilings. Into the afternoon, coastal terminals cleared to VFR. Satellite imagery shows the inland valley fog has been slower to erode as well. Overnight, KACV should see the stratus fill back in, potentially to LIFR levels. There is growing support from HRRR and high-resolution wind guidance that some of the stratus layer may be transported north to KCEC in the early morning hours via a coastal wind eddy. The reach to KCEC may be brief, and the conditional nature to generate the lower Cigs prompts only moderate confidence at this time. Conditions are anticipated to begin improving through midday, eventually to VFR. KUKI will remain VFR. /JJW && .MARINE...Northerly winds and steep seas will continue to increase this evening, and will remain elevated, especially in the northern waters. A few gale force gusts will be possible in isolated areas, including downwind of Cape Mendocino and Pt St George, but are not expected to be widespread enough to warrant a gale warning. Steep seas will build to 7 to 11 feet in the outer waters and south of Cape Mendocino. There is also a 1 to 2 foot southerly swell around 16 seconds and a 2 to 3 foot swell at 10 seconds that will persist through the week, along with continued steep seas with the northerly winds. The latest guidance shows the steep seas of over 5 feet and winds over 20 kt only briefly pulsing into northern inner waters at times, so will not issue a small craft advisory. However, it will be close to these conditions and it may be needed. /JJW && .EKA WATCHES/WARNINGS/ADVISORIES... CA...Heat Advisory from noon Monday to 10 PM PDT Tuesday for CAZ105- 107-108-110-111-113>115. NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 3 AM PDT Wednesday for PZZ470-475. Small Craft Advisory until 5 AM PDT Monday for PZZ455. && $$ Visit us at Follow us on Facebook and Twitter at: For forecast zone information see the forecast zone map online:
Area Forecast Discussion
National Weather Service Indianapolis IN
1143 PM EDT Sun Jun 21 2020 .UPDATE... The AVIATION section has been updated below. && .SYNOPSIS... Issued at 208 PM EDT Sun Jun 21 2020 A pair of upper level weather disturbances are expected to push across Indiana over the next few days...providing daily chances through Tuesday. Rain amounts with these systems will be light. High pressure is expected to arrive across the area by Wednesday...providing dry weather for mid week. Chances for showers and storms will return next weekend. && .NEAR TERM /Tonight/... Issued at 700 PM EDT Sun Jun 21 2020 Extended small PoPs over the east through 06z to match adjacent offices. Previous discussion follows... Issued at 208 PM EDT Sun Jun 21 2020 Water vapor imagery across the area shows a short wave trough in place IL and KY...pivoting into Indiana. Radar shows showers and storms over central Indiana...ahead of this system progressing across the state. Associated cloud cover has also prevented much heating and instability. Models suggest the short wave responsible for the rain will quickly exit to the east late this afternoon and early this evening...bringing ongoing rain to a quick end. Forecast soundings overnight indicate a drying trend and HRRR shows dry weather overnight. Mid levels show dry air arriving amid subsidence. Thus will trend for some pops through 00Z late tonight...otherwise a dry forecast will be expected Overnight. Given the little change in the overall air mass and decreasing clouds expected through the night...will not veer far from the NBM on temps. && .SHORT TERM /Monday through Wednesday/... Issued at 208 PM EDT Sun Jun 21 2020 The models continue to indicate broad cyclonic flow in place aloft through Wednesday. Yet another shorty wave within the flow is expected to push across Indiana on Monday afternoon and Monday Night. Forecast soundings at that time show pwats over 1.83 inches with attainable convective temperatures but limited CAPE. Thus enough forcing and moisture is expected for some pops and isolated tsra. Will mainly focus precipitation chances during the afternoon and evening as the short wave passes. Given the expected sunshine and heating early on in the day...will trend highs at or above the NBM. The Short wave quickly exits the area on Monday night...and forecast soundings show subsidence and drying within the column through Tuesday. Cyclonic flow aloft remains and forecast soundings show limited instability. Thus will try to trend toward a dry forecast on Tuesday as confidence in diurnally driven storms is low given the dry air aloft. Will stick close the NBM temps here. The flow aloft remains cyclonic through Wednesday as Ridging builds across the Plains states. This continues to place Indiana within an area favorable for subsidence. Meanwhile at the surface high pressure is expected to build across the Ohio valley from the Central plains. Thus will trend toward a dry forecast on Wednesday and Thursday with temps near the NBM. && .LONG TERM /Wednesday Night through Sunday/... Issued at 218 PM EDT Sun Jun 21 2020 Surface high pressure will continue building into the area Wednesday night to Thursday, allowing for dry conditions in that time frame. There is a small chance for light rain at times Thursday. Models are in pretty good agreement for the start of the long term, but varies more into next weekend and thus lowering the confidence in the forecast, particularly with timing of any weather. Did go with guidance as it looked good given the model variations in the long term. Generally though, models hint at a system approaching the area while a high sits to the SE, off the Atlantic coast. This will likely allow Gulf air into the Ohio Valley and thus rain chances for the weekend. Best PoPs at the moment look to be Friday night through Saturday. Temperatures will start out slightly below normal, but will trend to above normal by the weekend. && .AVIATION /Discussion for the 22/06Z TAF Issuance/... Issued at 1143 PM EDT Sun Jun 21 2020 Convective allowing models and radar trends suggest dry conditions until after 15z, when shower and thunderstorms will be possible and increase during the afternoon. GFS LAMP suggest MVFR or worse fog and ceilings possible mainly 09z- 13z. MVFR ceilings will again be possible after 00z Tuesday. Winds will be light and variable overnight and southwest to 12 knots after 18z. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Puma NEAR TERM...Puma/MK SHORT TERM...Puma LONG TERM....KH AVIATION...MK
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
930 PM CDT Sun Jun 21 2020 .UPDATE... 930 PM CDT Earlier local storms have all faded with the diurnal weakening of instability in an atmosphere void of any appreciable shear. Attention continues on Monday. It`s still too early for observational trends to provide much insights into specifics for Monday, so much of the Short Term AFD is very representative of the expectations, the conditional severe weather potential, and the plentiful uncertainties on precise evolution. One thing we will note is that the chances for some showers and potentially storms into north central Illinois sometime during the morning has increased some, though by no means a definite. Quiet conditions through at least early overnight look to prevail across the area. There might be patches of shallow fog in the locales that saw showers late in the day due to very low temperature-dew point spreads in a high moisture boundary layer. A mesoscale convective system (MCS) across the WI/MN/IA border region is moving east this evening at about 50 mph, driven by convectively-enhanced short wave that is moving slightly north of east. On its trailing edge in north central to northeast Iowa, the low-level jet of near 30 kt is largely offsetting a quick progression there, which would be closer or into our latitude. This means that the current timing of any rain chances later in the night and primarily over north central Illinois or near the Wisconsin border look good, with some outflow from this feature potentially sparking scattered development. The organized development through daybreak looks likely to remain to our northwest and north, potentially not by very far though. Further west, scattered convective development is likely over western into much of central Iowa overnight, and seeing signs of this over Nebraska as an approaching short wave nears and the favorable inherent environment sampled by the 00Z OAX sounding. How widespread this convection becomes and how it organizes with the aforementioned current northern Iowa regenerating activity is uncertain, though still at least a loose MCS is more favored than not moving eastward over the Mississippi River by daybreak, and as mentioned some scattered activity could be ahead of that into north central Illinois. Also an important feature is likely the well-organized MCV over central Kansas. The driving short wave and the MCV itself from this is seen on several guidance solutions, including the 00Z NAM and especially multiple RAP runs, progressing toward the northern Illinois region by midday. Obviously with so many mesoscale influences that have a domino effect and several of which are still maturing or even yet to develop, it makes Monday`s forecast very tricky. However the likelihood of thunderstorms, quite possibly a couple rounds worth, is favored over a decent amount of the area Monday and Monday evening. Maturity of any morning activity and influence on timing will likely dictate the conditional severe threat area and types, with MCVs playing a role to where there will be pockets of sufficient shear for better storm to mesoscale organization. MTF && .SHORT TERM... 317 PM CDT Through Monday night... Showers and storms are percolating mainly across the southeastern half of our CWA at this hour within a ribbon of maximized low-mid level moisture in the wake of yesterday`s activity. The diurnally-bubbling cumulus field gets progressively flatter with north and westward extent towards the Wisconsin/Illinois state line where instability drops off as dewpoints have mixed out into the upper 50s and lower 60s. Continue to confine the `highest` PoPs this afternoon generally east of I-55/57, but have also dragged some very low (20%) chances farther west and south of I-88 as somewhat lumpier Cu/towering Cu has developed west of I-39. Deep layer shear is very low and storms are exhibiting classic pulse type characteristics and cores are raining themselves out within 30-45 minutes. Surface-700 mb theta-e deficits are fairly high given the presence of some pretty dry air in the mid-levels, so can`t rule out some gusty winds as cores exhaust themselves. In addition, storms are moving very slowly (less than 15 mph) so a threat for locally heavy rainfall does exist. Storms will diurnally wane with the loss of heating this evening. The main focus during the short term portion of this forecast remains squarely focused on Monday which continues to feature what looks to be quite a messy forecast. This period also continues to exhibit higher-than-normal uncertainty at this relatively short range with the evolution of storms chances and the attendant severe weather threat tied to subtle mesoscale processes which remain fairly nebulous at this point. That said, a conditional threat for some severe weather does exist tomorrow but does depend on things evolving in a particular manner through the morning hours. A fairly sharp shortwave has translated east of the Continental Divide and is now progressing out across the central Great Plains. As this feature encounters an increasingly unstable and uncapped environment, showers and thunderstorms are expected to develop across Nebraska and northeastward into Minnesota along a cold front. Storms should then congeal into a forward-propagating MCS through this evening and overnight and track generally eastward across Iowa. Confidence through this part of the forecast (through tonight) remains fairly high as a result, but begins to degrade pretty quickly thereafter. Overall, the MCS parameter space doesn`t appear all that impressive, with generally weak deep layer shear and also directed somewhat parallel to the anticipated MCS orientation at our latitude. This should work against the regenerative development of new/robust updrafts at the leading edge of the accelerating cold pool and would, as a result, expect a gradual weakening trend as outflow is exhausted from the convective carcass by and just after daybreak. At that point, it looks like this complex may be sneaking into our CWA at early Monday morning in its weakening phase although can`t rule out some lingering gusty winds with the anticipated outflow. Depending on exactly how early or late in the morning that this feature moves into the area, subsidence and the associated convectively-processed airmass could keep thunderstorm chances to a relative minimum through the morning or even into the early afternoon hours. If this feature is lingering overhead by midday, the subsequent strong-severe weather threat may stay pretty muted in the afternoon as temperatures will have limited time to recover ahead of the next shortwave. It`s just too early to tell how this will shake out as the convective complex hasn`t taken shape yet. If we are able to clear out a bit through the late-morning and early-afternoon, a threat for strong-severe storms will then be possible as the next shortwave drops southward out of Minnesota/Iowa with convection potentially developing on any leftover outflow. A second area of thunderstorms could conceivably develop on a cold front off to our west potentially yielding two corridors of initial storm development. Outside of any mid-level flow augmentation near any remnant MCV`s, deep layer shear looks to once again remain pretty weak which should temper storm organization. As a result, and given weak mid-level lapse rates, would expect the main threats to be from strong to potentially damaging wind gusts--especially if storms can develop and then congeal into another complex. Obviously lots of uncertainties here, and it`s pretty difficult to highlight a favored corridor for these severe threats at this point, although latest indications are that this *may* maximized locally east and south of I-55 through the afternoon. Will hold onto relatively high PoPs through Monday evening as well as guidance does suggest additional development on the incoming cold front although would envision the severe weather threat with this activity may remain more muted. Carlaw && .LONG TERM... 325 PM CDT Tuesday through Sunday... Monday night`s cold front passage will usher in a cooler and drier low level air mass that will be with us through Wednesday night. Most of that time will be dry, but isolated to perhaps widely scattered diurnally driven instability PM showers will be possible on Tuesday and Wednesday. Upper level low pressure will set up south of James Bay and then slowly translate eastward through Thursday night. In the northwest flow on the southwest periphery of the troughing influence of the upper low, occasional short-wave impulses may touch off the aforementioned diurnally driven showers as lower level lapse rates steepen. Tuesday`s instability looks quite meager, enough so that thunderstorms continue to appear unlikely. Wednesday may have a bit more, but still low instability to enable a few isolated thunderstorms amidst widely scattered afternoon showers. On Thursday, as the upper low finally kicks east, temperatures will warm to around normal low-mid 80s, though humidity will still be low. Any afternoon convection should be widely isolated, with minimal instability and less forcing. The main timeframe to watch this week after Monday`s potentially widespread convection is Friday into the weekend. A warm front will lift north Thursday night into Friday, with warm and more moist advecting in with a lead short-wave possibly kicking off showers and thunderstorms toward morning. Depending on how the morning evolves with regard to effects of possible morning storms on daytime heating and destabilization, there may be another round on Friday afternoon into at least the evening. Thermally, temps in the upper 80s will be possible, if not warmer, but a messy convective evolution would likely limit things a bit. Ensemble mean PWAT approaching 1.75" and operational solutions offering up potentially nearing 2" PWATs would support a heavy rain and flooding risk with Friday`s likely storms. Meanwhile, there may be enough west to west-northwest mid-level flow on Friday PM for some strong/severe risk. A weak cold front could try to shift the instability axis a bit southward over the weekend, though possibly still in the CWA, so the muggy and unsettled weather could continue with occasional shower and thunderstorm chances, with above normal temps). Castro && .AVIATION... For the 00Z TAFs... Quiet conditions are expected through the overnight hours at all sites as widely isolated diurnally-assisted activity over northern Illinois quickly diminishes over the next hour or two. Winds will settle at S/SSW under 10 knots overnight. The forecast becomes quite complex by mid-morning Monday. Developing convection from northeast Nebraska into southwest Minnesota is expected to move eastward through tonight, reaching northern Illinois in a decaying mode Monday morning. Uncertainty with how quick this decay occurs complicates the forecast for the remainder of the day at the Chicago metro sites, though some SHRA and possible TS should survive to around RFD. There are two scenarios that could unfold for the Chicago area sites on Monday: 1) Overnight convection weakens considerably, producing little impact in the Chicago area Monday morning. New convection will then quickly develop on the remnant outflow over the metro early in the afternoon. After an early evening lull, scattered convection is possible on a cold front arriving late in the evening. 2) Overnight convection is slow to weaken, bringing residual SHRA and gusty west winds through the Chicago area mid-morning. The stabilizing effect and farther SE push of the outflow could keep most afternoon convection southeast of DPA/ORD/MDW. Evening convection will remain possible along the cold front. A better idea of which scenario will unfold likely will not be realized until the overnight hours once convective trends over Iowa become more clear. Kluber && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Shreveport LA
1013 PM CDT Sun Jun 21 2020 .SHORT TERM.../Tonight/ The evening mosaic radar imagery continues to indicate a broad MCV spinning between FSM and RUE, with convection having become enhanced across the very moist and unstable environment to its SSE over the Nrn sections of SW and SCntrl AR, where PW`s near 2" and MLCapes of 1500-2000 J/KG persist. With the air mass becoming stabilized with the increasing convection, the primary threat tonight will focus to a heavy rain and potential flood threat, as a 20-30kt SWrly low level flow continues to feed into the MCV as drifts slowly E overnight. Whereas the 12Z and 00Z global models have been underdoing the QPF thus far, a few of the latest CAMs including the HRRR, ARW, and RAP suggest that widespread 2-5+ inch QPF are likely across portions of SW and SCntrl AR, although each vary in the exact location of the higher totals. The highest confidence though for seeing the potential for flash flooding is only across a small area from Howard to Hempstead and Nevada Counties, as well as Union County, but these areas have remained drier than normal over the last month and should be able to take most of these rains and thus, a Flash Flood Watch will not be issued with the forecast update. Also of note is the ongoing MCS across NW OK, which is quickly advancing SE across Wrn into Ncntrl OK attm, with the 00Z CAMs suggesting that this complex will hold together (although in a weakened state) mainly NW of I-30 into extreme NE TX/SE OK/adjacent SW AR by and just prior to 12Z. With this complex moving across much of Cntrl and Ern OK overnight which remains more stable than areas to the SSW over Srn OK/NW TX, this MCS should weaken as it approaches the region, and should remain progressive enough such that the flash flood potential over McCurtain County should be reduced in wake of the widespread 2.5-5 inches of rain that fell earlier today. For the evening update, did raise pops considerably to categorical/likely over the Nrn sections of SW AR, while also beefing up pops to likely/high chance farther WNW after 06Z for SE OK/extreme NE TX. Given the uncertainties of the NW OK MCS late tonight, did not make any changes to the pops Monday, although a cold pool/outflow boundaries from this convection should help focus at least sct convection during the day farther SE across the remainder of the region. Did lower min temps a bit tonight across the rain cooled areas of SE OK/SW AR, while also removing pops for Lower E TX/much of N LA where the seabreeze convection has diminished and the air mass having stabilized. Zone update already out...grids will be available shortly. 15 && .PREV DISCUSSION... /issued 728 PM CDT Sun Jun 21 2020/ AVIATION... VFR conditions will continue this evening, with the sct convection winding down for the most part with the stabilizing air mass. However, the exception will remain over the Nrn and NE sections of SW/Scntrl AR, near and E of an MCV that will drift E into SCntrl AR overnight. Thus, sct convection will remain prevalent near and N of the ELD terminal tonight, and thus have continued VCTS mention here through much of the overnight period. Otherwise, elevated convective debris will linger overnight, with low MVFR/possibly IFR cigs develop around or just prior to 12Z Monday areawide, which look to linger through much of the morning before becoming VFR by late morning/early afternoon. However, some uncertainty with the duration of these cigs exist as a SE moving convective complex (MCS) over Srn KS/NW OK will slide SE through OK overnight, which may enter SE OK/portions of NE TX by/shortly before 12Z Monday as it decays. Thus, a cold pool from this decaying convection may shift SE across the region by mid to late morning, thus focusing at least sct convection with the aid of diurnal heating. An earlier cold pool/outflow bndry would tend to quickly scatter/lift any low cigs Monday morning, with sct convection primarily affecting Deep E TX/N LA/SCntrl AR during the afternoon. Have added VCTS to all but the TYR/GGG/TXK terminals Monday afternoon. S winds 6-12kts tonight will become SSW 10-15kts with higher gusts after 15Z. /15/ && .PRELIMINARY POINT TEMPS/POPS... SHV 75 91 74 84 / 10 40 40 90 MLU 72 91 74 87 / 20 50 30 90 DEQ 69 87 69 85 / 60 60 80 80 TXK 72 88 71 81 / 50 50 80 90 ELD 70 89 71 82 / 70 40 70 90 TYR 75 91 71 84 / 10 40 50 80 GGG 75 91 71 85 / 10 30 40 90 LFK 74 92 73 87 / 10 40 20 90 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 15
Area Forecast Discussion
National Weather Service Tulsa OK
925 PM CDT Sun Jun 21 2020 .UPDATE... The forecast was updated based on the latest short term data and recent obs trends. See discussion below. && .DISCUSSION... As has been anticipated for at least a couple days now, an MCS has evolved out of cluster of severe storms over western KS this afternoon. Over the past couple hours, some trends have been noted in area radar data, and suggest that the last few runs of the HRRR are painting a reasonable idea of how this will evolve. The initial MCS split in two, with the eastern flank surging out toward Wichita to the south of a book end vortex. This convection has since become very disorganized and no longer is severe. The storms on the western flank were more intense and have now evolved into what looks like the main show for the overnight across northwest Oklahoma. The CAMs take this MCS southeast overnight, tracking into east central and southeast Oklahoma toward the early morning hours on Monday. While the environment over much of eastern Oklahoma is far from ideal for convection, some improvement in conditions is possible down toward the Red River overnight ahead of the MCS as effects from the MCV over the Arklatex continue to wane as it shifts east. Based on the latest radar and CAM data trends, PoPs have been adjusted to focus the higher numbers from east central down into southeast Oklahoma after midnight. Damaging winds remain the primary severe threat, though with some uncertainty regarding the environment over eastern OK ahead of it, have toned down the wording just a bit. Updated products and graphics have been sent. Lacy && .PREV DISCUSSION... /Issued 652 PM CDT Sun Jun 21 2020/ AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG. Increasing high level clouds and winds between east and south should remain common across the CWA this evening. Overnight... attention turns to the MCS ongoing across Western Kansas. Latest short term guidance continues to indicate this complex diving more southerly through Western/Central Oklahoma before reaching Southeast Oklahoma late tonight. Thus...will trend this set of TAFs in that direction and hold onto VCTS for a period in Northeast Oklahoma with thunderstorms and tempo groups for Southeast Oklahoma. Across Northwest Arkansas...there is still a chance of a few storms and will continue with VCTS/tempos early Monday morning. Otherwise...there could be the potential for some MVFR ceilings during this time period. Within the convection...MVFR conditions along with gusty winds will be possible. During the day Monday...precip chances look to decrease by mid/late morning with prob30 groups covering the afternoon hours. Scattered to broken mid and high clouds and winds becoming westerly are also forecast during the day Monday over the CWA. PREV DISCUSSION... /Issued 201 PM CDT Sun Jun 21 2020/ DISCUSSION... Almost looks like we have two MCVs drifting across southeast Oklahoma this afternoon. These features continue to produce scattered showers and thunderstorms across southeast Oklahoma into western Arkansas this afternoon. This activity is expected to diminish as we move closer to sunset. With MLCAPE values running around 2000 J/KG, these storms could become briefly strong to marginally severe. We will then focus our attention to the north this evening as thunderstorms are expected to develop across western Kansas in the vicinity of a surface boundary in the lee of the Rockies this afternoon and spread to the southeast. This activity is expected to coalesce into a MCS and move into northeast Oklahoma as we approach the midnight hour and then across the remainder of the area through the night into Monday morning. The main concern with this thunderstorm complex as it moves through the area will be damaging winds and heavy rains. The chances of showers and thunderstorms persist through the Monday afternoon and into Tuesday morning time-frame in the vicinity of any residual outflow boundaries and in the area of any MCV type features. This activity will also be enhanced by a synoptic cold front moving into the area as a mid-level shortwave trof plows across the Plains. There is expected to be adequate instability and deep layer shear for any these storms to become severe with damaging winds and large hail the concern. Tuesday night into Wednesday appear to be mostly dry as high pressure builds into the region behind a reinforcing cold front. More showers and thunderstorms are possible late in the week as a the front moves back to the north and east across the area. Still looking at the potential for another 1 to 3 inches of rain through Tuesday with locally higher amounts possible. Localized flooding of low lying areas will be possible. Stayed close to NBM temperatures through the forecast period. && .PRELIMINARY POINT TEMPS/POPS... TUL 69 86 67 85 / 50 50 60 10 FSM 68 86 70 87 / 50 60 90 40 MLC 69 85 68 84 / 60 60 80 40 BVO 68 85 65 84 / 40 50 50 0 FYV 66 82 65 82 / 30 60 80 30 BYV 66 83 65 82 / 10 60 70 30 MKO 69 86 67 84 / 40 60 80 20 MIO 67 84 65 84 / 40 60 50 10 F10 68 86 67 84 / 50 50 80 20 HHW 69 86 70 84 / 80 60 80 60 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...30