Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/09/21

Area Forecast Discussion
National Weather Service Cheyenne WY
513 PM MDT Tue Jun 8 2021 .SHORT TERM...(Tonight - Thursday Night) Issued at 227 PM MDT Tue Jun 8 2021 A very strong cap remains evident across much of southeast Wyoming and the western Nebraska Panhandle this afternoon w/ quite limited cumulus development thus far. We should start to see an increasing low-level cumulus field in the next couple of hours as we approach our convective temperatures, but w/ upwards of 50 J/kg MLCIN still present the likelihood of afternoon initiation appears low. HRRR & other high-resolution guidance have continued to suggest some more robust development between 00 and 02z along the lee trough/dryline or roughly along I-25. Deep layer vertical shear is very modest at around 20 knots over most of the area, but area forecast soundings show appreciable low-level directional shear which would suggest a good possibility of upscale growth into a linear system across the western NE Panhandle during the mid/late evening. Substantial low- level mixing has occurred today w/ dew points falling to around 50 F although some 60s still linger over our far eastern zones. CAPEs in excess of 2000 J/kg will support a large & damaging hail threat with any discrete storms. Otherwise, extremely steep low/mid level lapse rates and large boundary layer T/Td spreads, along w/ DCAPEs of 1500-2000 J/kg will support a threat for damaging straight line winds with the eventual MCS. Lingering outflow from Mondays storms could locally enhance low-level shear & contribute to a chance for an isolated tornado if the quality of moisture is sufficient. This is especially true along a Wheatland-Sidney line. A brief period of upper-level ridging should limit chances for any storms on Wednesday, but the next chance for strong/severe thunder storms will arrive Thursday as a vigorous short wave ejects north- northeast across the Great Basin. Increasingly difluent flow aloft should overspread the area, leading to an eroding cap & initiation by late afternoon. Timing will be crucial here w/ regard to severe potential, but very steep mid-level lapse rates & dew points 55-65 deg F may contribute to CAPE in excess of 3000 J/kg to the east of the lee trough/dryline while 0-6 km shear should be very strong at 35-45+ knots. All modes of severe weather would be possible. Would not be surprised if the current Day 3 SLGT is expanded further S & W in later updates. .LONG TERM...(Friday through Monday) Issued at 345 AM MDT Tue Jun 8 2021 Shortwave trough quickly exits northeast of the CWA by Friday morning, followed by an expanding upper ridge over much of the CONUS through early next week. Large scale subsidence and lack of moisture will preclude convective precipitation through the long term. Near normal temperatures Friday will warm to above normal with 80s and 90s this weekend. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 507 PM MDT Tue Jun 8 2021 VFR conditions across all terminals this evening with chances of thunderstorms at KCYS and all Nebraska panhandle TAF sites. Clouds will begin building in in the next few hours with thunderstorms beginning at KCYS around 00Z and moving eastward into the Nebraska panhandle through the night. Conditions should clear in the Nebraska panhandle between 8Z and 10Z, then depending on if the skies clear and the leftover moisture from the thunderstorms there`s a possibility for patchy fog, but confidence is currently low for the fog. && .FIRE WEATHER... Issued at 330 AM MDT Tue Jun 8 2021 Elevated to critical humidities and winds are expected west of the Laramie Range, with non-critical humidities and winds along and east of the Laramie Range through the end of the week. Fuels remain green, but may become more favorable for rapid fire growth west of the Laramie Range by the end of the week. Widely scattered showers and thunderstorms will develop this afternoon and evening along and east of Interstate 25, and over the Nebraska Panhandle Thursday evening. && .HYDROLOGY... Issued at 330 AM MDT Tue Jun 8 2021 Mild to warm temperatures will contribute to mountain snowmelt runoff and elevated stream/river levels, especially across southeast Wyoming. No sites are forecast to rise to minor flood stage, however with the diurnal rise and fall, it is possible waters may approach action stage later this week. With the lack of measurable precipitation west of the Laramie Range, the risk for rain on snowmelt will be negligible. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...CLH LONG TERM...MAJ AVIATION...LK FIRE WEATHER...MAJ HYDROLOGY...MAJ
Area Forecast Discussion
National Weather Service Glasgow MT
1203 PM MDT Tue Jun 8 2021 .DISCUSSION... 1130AM UPDATE: Morning dewpoints have begun to rise across the area but have not reached critical mass yet for thunderstorms development. Dewpoints also seem just underneath what some of the CAMs have been displaying for this hour. While dewpoint rises may be delayed an hour or so, strong east winds are already ratcheting up and 60+ dewpoints are just on the doorstep of the CWA in North Dakota. In addition there is plenty of light to moderate strato-cirrus flowing in from the south which is helping to keep the current stratus from destabilizing into full convection as fast. But, a couple morning thunderstorms around 9AM did prove that the atmosphere at least aloft is ready to pop. For these reasons we will be doing a 19Z upper air sounding to try to get a more accurate feel for precipitable water, timing of cell development, and hopeful improvement to the HRRR model as the afternoon progresses. GAH MORNING DISCUSSION: A wave moving through SE Montana early this morning is bringing some showers and thunderstorms to the SE part of the forecast area. The rain will move to the east shortly after sunrise this morning. SW flow aloft combined with an ESE low level flow will bring increasing moisture into the area today. Look for a rapid rise in dew points from 25 west to 45 east at 2 am (08Z) to 55 to 65 across the area this afternoon. A warm front lifts north through SE Montana today with a surface low. The front is expected to stall somewhere south of the Missouri River this afternoon and remain stationary tonight as the low moves into North Dakota with a cold front. An inverted surface trough to the NW of the surface low will become the focus area of convection today and tonight. The trough will combine with several ingredients necessary for severe thunderstorms. CAPE will as high as 4000 J/Kg range this afternoon and evening in the east. Lapse rates and shear values will also be strong. SPC has maintained a slight risk for severe thunderstorms, with an embedded hatched area for possible tornadoes and hail that could exceed 2 inches in diameter. Locally heavy rainfall is possible as precipitable water approaches 1.75 inches. There is a potential for 2+ inch downpours especially north of the Missouri River that even in a severe drought could bring flash flooding. Will issue a Flash Flood Watch for areas north of the Missouri River for late this afternoon and tonight. East winds will be strong enough today and this evening for a Lake Wind Advisory for Fort Peck Lake. Wednesday for the most part will be a break between system with a shortwave ridge in the SW flow aloft. A cold front in western Montana ahead of an upper trough in the Pacific NW will bring thunderstorms to central Montana that could move through the western zones of the forecast area Wednesday Night. The upper trough and cold front moves into the forecast area Thursday afternoon and evening. Atmosphere once again will be very unstable ahead of the cold front with CAPE exceeding 3000 j/kg in some areas. Look for thunderstorms with heavy rain possible and another round of severe thunderstorms as strong as today`s. Chances for showers and thunderstorms will linger into Friday especially in the NE as the upper trough moves into Canada. The weekend looks dry with an upper ridge and surface high pressure. && .AVIATION... LAST UPDATED: 1745Z FLIGHT CAT: VFR-IFR DISCUSSION: A mix of IFR, MVFR and VFR this afternoon and tonight. A few showers and thunderstorms will move through the KGDV through 14z this morning. Low pressure and warm front will move north into SE Montana today. The low will move northeast into NW North Dakota tonight. Showers and thunderstorms will develop this morning in the KGGW and KOLF areas this morning and spread into the KSDY and KGDV areas this afternoon. Some storms will be severe with LARGE HAIL and DAMAGING WIND that could exceed 50 knots this afternoon and evening. Heavy rain will reduce visibility to IFR levels at times. Low clouds will bring a mix of MVFR and IFR ceilings at times tonight. WIND: East at 15 to 30 kts today. Turning to the north and NE and diminishing to around 10 kts tonight. Strong and erratic winds are expected near thunderstorms and in any outflows that occurs in thunderstorms. /GAH && .GLASGOW WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through late tonight for Central and Southeast Phillips...Central and Southern Valley...Daniels...Eastern Roosevelt...Northern Phillips...Northern Valley...Sheridan... Southwest Phillips...Western Roosevelt. Lake Wind Advisory until 9 PM MDT this evening For Fort Peck Lake for Central and Southeast Phillips...Central and Southern Valley...Garfield...McCone...Petroleum. && $$
Area Forecast Discussion
National Weather Service Grand Junction CO
901 PM MDT Tue Jun 8 2021 .UPDATE... Issued at 901 PM MDT Tue Jun 8 2021 Similar to last evening relative humidity was slow to recover though winds have significantly decreased and were, except for a handful of exposed sites in northwest Colorado, reporting values below criteria. Expect winds will continue to decrease, eventually giving way to drainage flows later this evening as the atmosphere decouples. Therefore, have allowed the Red Flag Warnings which were in effect for much of the area to expire. However, critical fire weather conditions will redevelop again Wednesday and Thursday, so we`re not out of the woods just yet. && .SHORT TERM...(Tonight through Wednesday night) Issued at 217 PM MDT Tue Jun 8 2021 The latest upper-air analysis places a shortwave trough lifting northeastward over portions of central Utah into far western Colorado. The associated midlevel jet and dry slot extends along the CO/UT state line. Boundary layer mixing into this layer has resulted in Red Flag conditions across most of the valleys. One place that is not as windy as previously thought is the highway 60 corridor. Some of the midslopes could be fairly close to 25 mph so did not want to cancel the warning there. The trough has also cooled the temps by a few degrees, which might have been missed by some of the models. Last night smoke from the Telegraph fire east of Phoenix spread into our area. Satellite still shows some of that smoke transporting northward and getting trapped in the higher valleys. Expected hazy conditions in the mountains through the evening. Critical fire weather conditions will linger through about sunset before typical drainage winds develop as the midlevel jet lifts north of the area. There may be a slight chance some of the smoke makes it into the low- level inversion late this evening. If the winds can decouple at some locations dry air should support temperatures cooling closer to normal tonight. Tomorrow a trough will impact the West Coast, and that jet begins to spread over the area through out the day. The axis of higher wind speeds will be focused across the northwest half of the forecast area, which is where Red Flag Warnings are now in effect. Although afternoon wind gusts will not be as high as today. The HRRR shows that more smoke from AZ might move through the southeast half of the forecast area again tomorrow. .LONG TERM...(Thursday through Tuesday) Issued at 217 PM MDT Tue Jun 8 2021 We`ll start out the long term cranking up the fan a notch, thanks to another passing shortwave embedded the prevailing southwest flow. Upper level heights tighten in response to the system rippling through, and its associated jet axis slides directly overhead. Dry atmospheric conditions and anomalously warm temps will mix those strong upper level winds down to the surface. Expect an early onset to gusty conditions as well as widespread critical fire weather conditions erupting where fuels are cured. Winds will be strongest across the northwest corner of the forecast area, where gusts may easily exceed 45 mph in the afternoon. Winds "taper off" near the Four Corners area, traversing east toward Pagosa Springs along the 160 corridor...however this just means gusts may be confined to 25 to 30 mph. Winds eventually weaken overnight with a bit of recovery in store for Friday. A slice of good news follows this system, thanks to the slightly cooler air mass behind the trough that will nudge highs down a few degrees. Sadly, this won`t last long as a beefy ridge builds back over the Southern Rockies. Cluster analyses show excellent agreement with anomalously higher heights building over the Intermountain West in the 4 to 7 day time period. This leads to high confidence in exceptionally warm and dry weather lingering through the weekend and into next week. Temperatures rise 5 to 10 degrees on Saturday and keep climbing to record temps by Monday. Just as an example, ensemble guidance has forecast 5 days in a row reaching or exceed 100 degrees F for the Grand Valley...Early season heat is not done just yet... && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 550 PM MDT Tue Jun 8 2021 Breezy southwest and west winds will decrease early this evening, decoupling by or shortly after sunset. This will allow winds to shift to a more normal drainage flow during the remainder of the night. However, deep mixing is expected to result in another round of breezy southwest winds Wednesday afternoon and early Wednesday evening, though wind speeds aren`t expected to be quite as high. Smoke from fires in Arizona, eastern Utah and northwest Colorado will bring some haze, but won`t limit visibility below 10SM at TAF sites. Clouds will remain limited and as a result, VFR conditions will prevail through the next 24 hours. && .FIRE WEATHER... Issued at 901 PM MDT Tue Jun 8 2021 Conditions are focused across northern Utah and northwest Colorado on Wednesday before once again spreading into most areas on Thursday. Southerly winds will gust 30 to 40 mph on Thursday. Zero chance of wetting rainfall until further notice but a slight cool down and decreased winds on Friday looks to ease the critical fire weather conditions. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...Red Flag Warning from 11 AM to 8 PM MDT Wednesday for COZ200-202- 203-290. Red Flag Warning from 9 AM Thursday to midnight MDT Thursday night for COZ200-202-203-205-207-290-292-294-295. UT...Red Flag Warning from 11 AM to 8 PM MDT Wednesday for UTZ486-487- 490. Red Flag Warning from 9 AM Thursday to midnight MDT Thursday night for UTZ486-487-490-491. && $$ UPDATE...NL SHORT TERM...KJS LONG TERM...ERW AVIATION...NL FIRE WEATHER...TGJT
Area Forecast Discussion
National Weather Service Goodland KS
1000 PM MDT Tue Jun 8 2021 .SHORT TERM...(This evening through Wednesday night) Issued at 239 PM MDT Tue Jun 8 2021 Satellite imagery and 500 mb RAP analysis showed southwest flow from the west coast to the northern Plains this afternoon on the backside of an upper ridge. A shortwave could be seen traveling from Utah/Colorado northeast towards southern Wyoming. Meanwhile, a closed low entered the Upper Midwest as high pressure tried to push northward into Kansas from Texas. At 2:00 PM MT, sunny skies prevailed for the western half of the region, with fields of cumulus clouds along and east of Highway 25. Breezy southeast winds gusted up to 35 mph, with temperatures mainly ranging in the low 80s to low 90s. For tonight, the aforementioned shortwave is anticipated to continue northeast into Wyoming and the northern Plains. Initially, storms should fire in eastern Wyoming this afternoon, congealing into a line/MCS as they progress into western Nebraska and the Dakotas. The southern end of this line could clip northern portions of the region late tonight into Wednesday morning. Have inserted a slight to low chance of thunderstorms along the Nebraska border and southward into northwest Kansas where guidance hints at activity in the morning hours. Whether storms will trail far enough south to make it into our area at all is very uncertain at this time. Shear ranging from 20-30 knots overnight/early Wednesday, moderate lapse rates at 6C/km or so, and increasing instability suggest that if storms make it into the region, a few strong to severe storms could develop. However, confidence in severe weather occurring is low due to the time of day and the likelihood that storms may be dissipating by the time they reach our area. Otherwise, expect lows in the upper 50s to upper 60s overnight with increasing cloud cover. Beyond thunderstorm chances, adequate moisture will allow for stratus to develop Wednesday morning, mainly east of the Colorado border. At this point it appears fog should generally stay to our southeast, but this needs to be monitored. Have included a small area of patchy fog from Leoti to Gove for now. Turning to Wednesday, thunderstorm chances dry up midday as cloud cover decreases and temperatures climb into the mid 80s to low 90s. Ridging builds over the region through the day and night, which should result in dry weather prevailing. Temperatures fall into the 60s Wednesday night. .LONG TERM...(Thursday through Tuesday) Issued at 325 PM MDT Tue Jun 8 2021 The extended period begins with high pressure over the southern Plains as the ridge continues to build. Overall very little has changed with the forecast from the previous forecast package. Thursday continues to look like a hot and humid day with gusty winds. Guidance continues to lower afternoon highs, but increase dewpoints across the area. Overall afternoon high temperatures in the low to mid 90s look likely, but the influence of the surface moisture will continue to make heat indices near 100 degrees especially over the eastern counties where the highest dewpoints reside. The strongest wind gusts look to be along and west of the Colorado border where lower dewpoints along with lower potential low level cloud cover reside allowing stronger afternoon mixing to occur. Thursday night, a surface cyclone develops over the northern Plains which as a result emits a southeastward moving cold front over the Tri-State area. Along and behind of the cold front gusty to potentially strong winds may occur during the early Friday morning hours as wind gusts up to 40 mph possible. An area of showers and storms may build southward from a MCS over central Nebraska but capping concerns keeps from introducing higher pops in this forecast package. The best area to see thunderstorms would be over Hitchcock and Red Willow counties in Nebraska along with Norton county in Kansas. Friday, relative cooler and less humid conditions will be in place in wake of the cold front and as the ridge breaks down. High temperatures for Friday will be in the upper 70s across western Kit Carson county to the upper 80s across the eastern Kansas counties. Gusty winds will continue through the morning but will weaken during the afternoon and evening hours. Saturday and Sunday, high pressure again looks to build across the southern plains as the formation of another ridge begins to develop on Sunday. Overall the weekend looks to remain dry, however a weak disturbance over the southern Rockies looks to create some shower and storm chances across SW Kansas, which may make it into southern areas of the CWA; confidence was to low at this time to introduce precipitation chances into the forecast. High temperatures for the weekend are forecasted in the mid 80s to low 90s. Into next week, guidance has another strong ridge developing over the plains as high temperatures rise back into the 90s. Overall the latter portion of the extended period looks to remain dry, however guidance is hinting at a shortwave over the northern Plains which may lead to an area of showers and storms moving over the area confidence is low this far out in this scenario so have left the forecast dry for now. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1000 PM MDT Tue Jun 8 2021 KGLD, VFR conditions are expected from taf issuance through about 08z before stratus and sub VFR cigs move in from the southeast from 09z-19z. Winds during the period from the southeast around 10kts. After 20z VFR conditions return with winds continuing from the southeast around 10kts. Its possible for sub VFR cigs to redevelop after 03z but confidence is low and tied to the NAM model. Some drizzle and fog are possible in the 09z-12z timeframe. KMCK, VFR conditions are expected from taf issuance through about 11z with sub VFR cigs in stratus moving in from 12z-16z. After 18z VFR conditions return. Winds at taf issuance from the southeast around 10kts continuing through the rest of the period. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...JBH LONG TERM...TT AVIATION...99
Area Forecast Discussion
National Weather Service Gray ME
1108 PM EDT Tue Jun 8 2021 .SYNOPSIS... Chances for showers and thunderstorms will continue to increase into the evening tonight. A cold front will settle into the region on Wednesday...with the chance for showers and storms continuing. Much drier and cooler air arrives across the region on Thursday before another weak disturbance brings the potential for showers late Friday and Saturday, along with temperatures below normal for this time of year. Drier weather and seasonable temperatures are expected for the second half of the weekend. A trough likely deepens across New England for the start of next week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... 1105 PM Update... This most recent update is only to remove the flash flood watch for southernmost New Hampshire. Continuing to monitor convection exiting southeastern New Hampshire and southwesternmost Maine. Latest radar imagery is indicating a mesolow about to cross into York County by 04Z.A few embedded heavier showers are associated with this feature, however most of the threat for thunder with torrential downpours continues to diminish. Temperatures have dropped considerably over southern New Hampshire where the rain has fallen this afternoon. Heat advisories expired earlier this evening. Have introduced patchy fog to a few areas in the forecast area, namely the Connecticut River and Merrimack Valleys. Shifting focus to northern sections of the forecast area where scattered showers and thunderstorms have weakened as they entered the forecast area. However, the latest HRRR has the precipitation regenerating and convection potentially redeveloping at around 06Z-08Z over southern interior Maine as the best instability shifts south across the region. Prev Disc... Surface observations show a boundary extending along the MA/NH border with dewpoints near 70 to the south of the line. This area will be the focus for convection this afternoon. Over the next few hours, expect thunderstorm coverage to increase, with multiple rounds of storms with rainfall rates of 1-2 inches per hour. These storms will be supported by CAPE exceeding 2000 J/kg and very deep warm cloud depths. Shear is minimal in this area, which will keep the severe threat more marginal, and the storm motion slow. An additional area to watch will be the Quebec border. Surface obs showed a weak trough through the St. Lawrence valley mid day, and storms have fired along the St. Lawrence and begun to move southeast. In this area the shear is much stronger, and will support some severe storms north of the border. As this shifts southwards into the western Maine mountains, some additional thunderstorms stretching into the northern edge of the CWA are possible. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... The surface trough continues its slow drop through our area. Drying well behind the front up in Quebec will gradually push into our region. This will be reflected in the decreasing dewpoints across the north. To the south, showers may continue to linger in the afternoon, but there is less focused forcing than today so expect coverage to be more limited. High temperatures will remain very warm in the south, with the 90s continuing in portions of the coastal plain. While above average, this is a downward trend from the past few days, and do not expect additional heat advisories to be needed. Wednesday night Drier air finally makes it fully into the region, allowing a welcome respite to the overnight heat with temps dropping back down into the 50s. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Thursday will feature much different conditions from what we will have experienced for the previous several days. The cold frontal boundary will be well to the south across the Mid Atlantic states, and cool Canadian high pressure will be building into New England during the daytime. This will be occuring as part of a much larger pattern change, where the ridge that has been bringing the extended period of heat and humidity will gradually retrograde toward the west late this week and this weekend, and a trough will deepen across Greenland and parts of the Canadian Maritimes. In the interaction between these two large scale features, small ridges and shortwaves will transit through the Northeast US. This will begin by Thursday, with the area of high pressure on Thursday progressing through our area and moving offshore by early Friday. An elongated shortwave will then move in from the west-northwest late Friday, bringing an increased chance of showers and even cooler conditions. This feature will stall across much of the area through at least early Sunday, keeping the threat for widespread showers across southern and central parts of the forecast area. Sunday appears to be the best chance for a respite from the showers, as a weak ridge crosses the Northeast, bringing increased sunshine and warmer temperatures for Sunday. But this will be short lived, as a slow moving low pressure and trailing cold front will likely approach from the west late Sunday and Monday, bringing an increased chance for widespread showers and storms again. By early next week, the trough that deepens across the Canadian Maritimes late this week will likely continue to retrograde westward and be centered close to New England. The global models have some differences in the placement of the trough by early next week. The GFS and its ensemble suite have the trough centered over New England and not as deep as the ECMWF and its ensemble suite, which has the trough centered across the eastern Great Lakes and deeper. Either way, early to middle next week is likely to feature cool and wetter than normal conditions, it`s just a matter of how much so that the different model solutions offer, with the ECMWF offering the cooler scenario. The amplification of this feature should become more clear over the coming days, but the important part to know for now is that it will be the major influence on our weather for much of next week. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... Short Term...Scattered thunderstorms are moving across southern New Hampshire and will move through MHT and PSM this evening, with a few as far north as CON. Moist conditions with VFR ceilings will prevail across the rest of the area. Some thunderstorms may also enter the northern portion of the area from Quebec later this evening. Tomorrow VFR with a chance of showers across the south. Long Term... VFR conditions will return by Thursday morning. Showers are possible late Friday and Saturday as a trough crosses the region. VFR conditions will return Saturday night and Sunday before a frontal boundary brings another chance of showers Sunday night and Monday. && .MARINE... Short Term...A few thunderstorms may move across the southern portion of the waters this afternoon. A weak front will drop south across the waters tomorrow shifting to northerly flow. Long Term... High pressure will cross the waters on Thursday and into early Friday, then a trough of low pressure will approach from the west Friday night and into Saturday. High pressure will then build in again from the west for Sunday. Low pressure and a frontal boundary will approach from the west late Sunday and Monday, possibly bringing SCA conditions Monday with freshening southerly winds and building seas. && .HYDROLOGY... Update... Have ended the Flash Flood Watch for southernmost New Hampshire after coordination with WFO Norton. The potential for flooding rains has diminished in this region. Prev Disc... Very moist airmass in place across the southern portion of the region with PWATs over 2 inches. Additionally forecast soundings show deep layer CAPE with warm cloud depths in excess of 10kft. The result is a very favorable environment for heavy rainfall and already rainfall rates in excess of 2" per hour have been observed. The focus for this convection will be on a surface boundary draped across the MA/NH border, with the current convection set up just north into NH have opted to go ahead and issue a Flash Flood watch for Hillsborough and Cheshire counties where the heavy rain will be focused. Some of the rain may also extend east into eastern Rockingham county later this evening but that area is flatter and less prone to flooding. With rivers running very low, not much concern for river flooding with this. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ Cannon
National Weather Service Jackson KY
1152 PM EDT Tue Jun 8 2021 .UPDATE... Issued at 1152 PM EDT TUE JUN 8 2021 Convection has diminished across far eastern Kentucky. Further west, additional activity is affecting locations west of I-75. Have freshened up the PoPs through the night, generally keeping the higher values across the western third of the area, which maintains continuity with the previous forecast. The 00z model guidance look to be a bit aggressive on the PWATs advecting into our area overnight, as the latest SPC Mesoanalysis shows the 2.0 inch values across western Kentucky. Instability is also modest across the area, with the latest RAP suggesting diminishing ML CAPE through the overnight. As such, any heavy rainers should be more short-lived across the area. Mostly cloudy skies look to prevail through the rest of the night, which should keep fog in check as well as hold temperatures up a bit more than last night. Did make a few adjustments to the lows at some locations, incorporating the latest trends in observations. UPDATE Issued at 817 PM EDT TUE JUN 8 2021 Most of the more organized convection has weakened and shifted off to our northeast, with the exit of a short wave trough. One more cluster of showers and storms is currently moving across our southeast, sustaining more from lingering instability downstream. This should exit in the next hour, with a relative lull in activity expected as we will be between waves. The next one is gradually swinging into central Tennessee/Kentucky. This will affect our area later tonight, especially the western third of our area. PWATs upstream are greater than 2 inches, and most of the model guidance has these higher values advecting in as the wave approaches. So far, some of the higher resolution model guidance is not indicating anything too heavy as far as precipitation amounts, despite a favorable environment for efficient rainers. Will continue to monitor trends through this evening. For now, tried to allow for a better depicted lull in the activity over the next 2 to 4 hours, before ramping PoPs back up into the likely category overnight and into the pre-dawn hours, particularly west. Forecast low temperatures look reasonable at this time, so have mainly blended in current observations, capturing the rain-cooled air already in place where recent convection tracked. Updates have been sent. && .SHORT TERM...(This evening through Wednesday night) Issued at 340 PM EDT TUE JUN 8 2021 We continue to see slow moving showers and thunderstorms develop this afternoon mainly along and west of I-75 and around the I-64 corridor. The greatest concern has been heavy rainfall given the weak northwest steering flow and ample moisture with PWATs in the 1.6 to 1.8 inch range. The lack of shear has also allowed some of these to become more multicellular in nature and further leading to periods of heavy rainfall. These will likely be mostly tied to the diurnal trends and would expect this activity to decrease in coverage through the evening. Tonight, we will see the decrease in coverage early, with perhaps some fog developing in areas that see rainfall and clearing. Right now best chance is in the far southeast in terms of fog. The upper low will meander east toward the Ohio Valley tonight and noticing some weaker waves riding through the mid-level flow. This could lead to increased showers and thunderstorms toward dawn Wednesday morning particularly in the western parts of the CWA such as the Bluegrass and Lake Cumberland regions. This will have to be closely monitored given this convection could be quite efficient in producing heavy rainfall, as PWAT values are expected to increase closer to 2 inches toward dawn. Wednesday, this weak upper level low will continue to push east and lead to likely PoPs for most through the day, with best chances remain in the western parts of the CWA. The peak of this convection will be in the afternoon and evening. Opted to go with chance for thunder given the lesser instability in place likely owing to cloud cover potential. Also, opted to drop afternoon highs a few degrees given the aforementioned cloud cover. Wednesday night, the coverage of convection is expected to once again wain, as we loose the little potential for heating we have during the day. We could see some patchy fog, but this will be more dependent on how the cloud cover shakes out. .LONG TERM...(Thursday through Tuesday) Issued at 320 PM EDT TUE JUN 8 2021 The large scale upper pattern in the extended will feature surface ridging over the southeastern CONUS, troughing over the northwest, and strong upper ridging building over the southwest. Over time, the southwest ridge looks to build in quite strongly and expand north and eastward. As this occurs, the large upper trough that will have come onshore already, will be displaced northward, and will migrate eastward along the northern edge of the strong upper ridge. Meanwhile, the southeastern ridge should weaken and become more elongated with time. Smaller scale features will include upper level disturbances and a slow moving area of low pressure aloft, all of which will move through the Ohio and Tennessee Valley regions through out the extended period. It is these smaller scale features that should provide the necessary lift required to aid in shower and storm formation across our area. Southerly to southwesterly flow around the western edge of the weakening southeastern ridge will provide the fuel for shower and storm formation, particularly during the afternoon and evening hours. It appears that we will see very good chances for late day shower and storm activity around eastern Kentucky through most of the extended, especially Thursday through Saturday night. The nighttime periods will also see decent chances for rain, as there should still enough lift, moisture, and instability present to support showers and storms. Locally heavy rainfall will be a concern on Thursday and Friday, as those appear to be the days during which we will see the highest precipitable water amounts and maximum low level moisture flux. The upper level low mentioned before may also be moving directly overhead by the end of the week. Temperatures should top out mainly in the 80s each day, with nightly lows falling into the 60s. Winds will be generally out of the south or southwest at around 5Kts each day and lighter at night. Dewpoint temperatures in the 60s and lower 70s will make for very warm and muggy conditions around the area. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) ISSUED AT 817 PM EDT TUE JUN 8 2021 Mostly VFR conditions will start out across the area through this evening. Skies look to remain partly to mostly cloudy, which should limit any fog development to mainly MVFR, although locations that have seen more significant precipitation could see IFR or lower conditions at times tonight. As such, have included IFR visibilities at SJS, with mainly MVFR elsewhere. An approaching upper level disturbance will also bring an increase in convection overnight from the southwest, affecting locations mainly along and west of a line from KSYM to KLOZ. During the day on Wednesday, convection will initiate across most areas, bringing MVFR or lower conditions at times. Winds will average around 5 kts or less generally out of the south and southwest through Wednesday morning, before peaking in the 5 to 8 kt range during the afternoon. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GEOGERIAN SHORT TERM...DJ LONG TERM...AR AVIATION...GEOGERIAN
Area Forecast Discussion
National Weather Service Louisville KY
1112 PM EDT Tue Jun 8 2021 .Forecast Update... Issued at 1110 PM EDT Tue Jun 8 2021 Some scattered KLVX returns currently ongoing across the region will continue tonight as a 500mb closed low spins over the Mississippi/Ohio Valley. KOHX VWP shows a marginal southerly LLJ of 30kts around 4-5k ft, which continues to help advect rich Gulf moisture into Kentucky. Mesoanalysis shows that PWATs are in the 1.7- 1.9" range, which has resulted in brief tropical-like heavy downpours. We`ve been watching rotating showers and mini supercell structures this evening, which is a bit unexpected considering an environment with only 30kts of Effective Bulk Shear and SRH values right at 100 m2/s2. However, believe these have ended for the night. Effective Bulk Shear will continue to diminish overnight, along with SBCAPE. Mesoanalysis notes current SBCAPE between 500-1000 J/kg across the region, but instability will be decreasing through the night as temps drop into the upper 60s. HRRR appears to have somewhat of a decent handle on current trends, which suggests we`ll see the current isolated showers over Breckinridge/Meade continue to lift northward and into southern IN. Best chances for scattered showers for the overnight period will be across the southern IN and Bluegrass zones. By sunrise tomorrow, scattered showers and storms look possible across the entire CWA, which will continue through the afternoon as peak heating destabilizes our environment. Updated near term grids from now to 12z, and will send fresh products shortly. && .Short Term...(This evening through Wednesday) Issued at 234 PM EDT Tue Jun 8 2021 Large upper level currently centered over Missouri continues to influence our active weather patten of showers and storms. We`ve seen a few bands of showers and storms develop along the eastern periphery of the low this afternoon, and this activity will gradually push off to our north and northeast through the day. Overall environment is not supportive of severe storms this afternoon and evening. Deep layer shear is fairly weak (<25kts). While instability is fairly modest (1000-2000 J/KG), it is spread out over a "skinny" CAPE profile where lapse rates are poor. These types of profiles tend to result in limited updraft strength, and weaker updrafts will not be as likely to result in strong gusty surface winds when the storm collapses... or send hydrometeors high/long enough above the freezing level to result in any meaningful hail. That`s not to say we won`t see an occasional strong storm that develops in a pocket of clearing and takes advantage of a localized area of enhanced CAPE... but think those will be quite uncommon compared to most convection that develops today. The "bigger" (albeit marginal risk) threat will be isolated flooding issues from training storms. Atmosphere is very juicy (+1.8" PWATs) and soundings show deep warm cloud layers supportive of torrential rainfall. The good news is that most of the convection is developing along east-west or northwest-southeast oriented bands with storm motions generally to the north and northeast. This should greatly limit any storm training threat and keep it isolated at best. Overnight, we should see a decrease in coverage or perhaps even a lull in activity before the next round of showers and occasional thunderstorms swing on through. This will likely continue well into tomorrow morning and afternoon, with much of the heavier showers and thunderstorms igniting during the afternoon with peak heating. The core of the upper level low currently in Missouri will be closer to us tomorrow, so winds aloft will be a bit weaker. Depending on how/where storms develop, there could be a slightly higher chance for flash flooding given slower storm motions and the potential for showers/storms to train. As a result, WPC has highlighted much of the region within a slight risk for excessive rainfall. .Long Term...(Wednesday night through Tuesday) Issued at 240 PM EDT Tue Jun 8 2021 Wednesday Night through Friday...The upper level low (ULL) is progged to be over the OH Valley by Wednesday evening, which will result in continued unsettled weather across southern Indiana and central Kentucky. The ULL will begin to deepen slightly while also becoming absorbed into the main flow aloft by Thursday evening and into Friday. This period will be characterized by continued moisture rich flow due to the positioning of the ULL and ridging across the SE US resulting in PWATs near 2.00 inches and a persistent chance of showers and thunderstorms with greater chances being diurnally driven. With several days of repeated rainfall and the potential for showers and storms to drop heavy amounts of rain at any given location, WPC has included our area within a Day 2 Slight Risk for excessive rain. But confidence in any given location experiencing flood concerns is low at this point. Temperatures will remain near climatological norms with highs in the low to mid 80s and lows each morning in the upper 60s to low 70s. Dew points will also remain high with values in the upper 60s to low 70s. Saturday through Tuesday...GEFS plumes show diurnal peaks in 3-hr QPF dropping significantly by Saturday through Monday as the remnant trough of the ULL passes SE of KY allowing for low amplitude upper ridging to build in overhead. PWATs also take a dive with values between 1.20 to 1.50 inches as mid level flow takes on a drier northerly component. With that said, there will still be afternoon chances of isolated pop up showers Saturday, but coverage will be sparse. Otherwise, the area should remain mostly dry over the weekend and into the beginning of the work week. With less cloud cover, we`ll see an increase in temperatures with daily highs reaching into the mid to upper 80s with some urban areas and typical hot spots possibly reaching 90. && .Aviation...(00Z TAF Issuance) Issued at 800 PM EDT Tue Jun 8 2021 Current precip is ongoing near HNB and BWG, but shower activity is expected across all TAF sites through the overnight hours. Could see a break in precip for a while around sunrise, which could result in some MVFR or low-end VFR vis due to BR. By late morning or early afternoon, shower and storm chances will ramp up again due to peak daytime heating. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...CJP Short Term...DM Long Term....CG Aviation...CJP
Area Forecast Discussion
National Weather Service Memphis TN
949 PM CDT Tue Jun 8 2021 .UPDATE... Showers and thunderstorms continue to develop along and south of the MS/TN border. The latest HRRR shows development in that area, but not this early. Flash flooding will be a concern through the overnight hours. Will update to make some adjustments to POPS and temperatures. KRM && .DISCUSSION... /issued 322 PM CDT Tue Jun 8 2021/ Ongoing showers and thunderstorms continue to track over the same general areas from east central Arkansas across much of north Mississippi. Precipitable water values of over 2 inches have resulted in rainfall rates up to 2.5 inches per hour. Widespread flooding has been reported across much of north Mississippi. Flash flood guidance has been exceeded by over 300% in some locations. In west Tallahatchie county MRMS guidance indicated over a 200 year return period. A Flash Flood watch and a Severe thunderstorm watch continue through 7pm. These products may be need to be extended. Overnight, a weak upper low likely responsible for enhancing storms across the area today will track east into Kentucky. However, much of the Midsouth will remain on the east side of a trough centered over east Arkansas. As a result, at least showers will continue with isolated thunderstorms. Any additional storms over north Mississippi could be problematic. Tomorrow, showers and thunderstorms will likely become enhanced once again during the afternoon hours. Currently the Storm Prediction Center only has general thunderstorms in their day 2 outlook. Lingering outflow boundaries from storms today and tonight, especially intersecting boundaries could help to initialize storms and enhance updrafts. Once again any additional rain where flooding occurred today and overnight could quickly exaggerate ongoing flooding issues or lead to additional issues. Diurnally enhanced showers and thunderstorms are likely each day across the Midsouth for the remainder of the work week. The weekend doesn`t look as dry anymore as it did in previous model runs. Temperatures should trend slightly warmer each day through the work week with upper 80s to low 90s returning over the weekend. 30 && .AVIATION... In the short term a line of TSRAs will impact KTUP through 01z with SHRAs thereafter. Expect more SHRA/TSRA development across N MS overnight into Wed AM. KMEM/KMKL will be on the periphery with some SHRAs. Otrw expect cigs to lower to IFR areawide overnight with LIFR likely at KJBR. Cigs will slowly improve to VFR by Wed afternoon with additional SHRA/TSRA development due to heating. South winds at 6-8 kts overnight becoming SSW at 7-10 kts with a few higher gusts Wed aftn. SJM && && .MEG WATCHES/WARNINGS/ADVISORIES... AR...Flash Flood Watch through Wednesday afternoon for Lee AR- Phillips. MO...None. MS...Flash Flood Watch through Wednesday afternoon for Alcorn-Benton MS-Calhoun-Chickasaw-Coahoma-DeSoto-Itawamba-Lafayette-Lee MS-Marshall-Monroe-Panola-Pontotoc-Prentiss-Quitman- Tallahatchie-Tate-Tippah-Tishomingo-Tunica-Union-Yalobusha. TN...None. && $$
Area Forecast Discussion
National Weather Service Topeka KS
1051 PM CDT Tue Jun 8 2021 ...AVIATION UPDATE... .DISCUSSION... Issued at 343 PM CDT Tue Jun 8 2021 The highlights of this forecast package include heat and humidity continuing to build this week before our next front arrives on Friday. Rain chances will increase with the approach of that next boundary late this week. Currently, a summer-like air mass remains dominate around the region. Aloft, a weak and disorganized upper low is somewhat evident on water vapor imagery approaching the lower Mississippi Valley. An amplified trough is moving toward the west coast of the CONUS and an upper ridge is building over Texas. The upper ridge will continue to expand northward into the area through midweek. Temperatures at 850mb will respond by increasing into the 21 to 23C range in central KS by Thursday afternoon, which is when surface highs are forecast to reach the low and mid 90s area-wide. Heat index values remain a concern Thursday afternoon with combined 90 degree temperatures and dew points near 70 degrees. That will result in apparent temps between about 97 and 103 degrees. A wave of energy associated with the troughing pattern out west will trigger convection along an associated surface boundary in the northern High Plains as it progresses into south-central Canada. That surface boundary will approach northeastern KS on Friday and some models have tried to bring an MCS into the area early in the day. The LLJ decreases Friday morning, mid level temperatures remain warm and models are starting to back off on that solution. Rather, the better threat for storms may be with redevelopment along the boundary late in the day Friday. Before rain chances arrive, however, we can expect another very hot and humid day for locations ahead of the front Friday afternoon. Heat indices in those locations could range from 100 to 105 degrees. Upper ridging could then build back in this weekend, allowing for warm but fairly dry weather. && .AVIATION...(For the 06Z TAFS through 06Z Thursday) Issued at 1051 PM CDT Tue Jun 8 2021 No big changes the forecast thinking. The RAP forecast soundings still suggest a marginal chance for ground fog around sunrise. Confidence and potential impacts to the terminals seems to be on the low side to include a tempo in the forecast at this time. Otherwise think VFR conditions will continue with diurnal CU redeveloping by the late morning. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Teefey AVIATION...Wolters