Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/28/20

Area Forecast Discussion
National Weather Service Bismarck ND
941 PM CDT Sat Jun 27 2020 .UPDATE... Issued at 941 PM CDT Sat Jun 27 2020 Convection from near Minot to Dickinson and Bowman is diminishing concurrent with increasing MLCIN in RAP-based objective analyses, albeit a bit more slowly than earlier anticipated. We`ve adjusted the forecast slightly to accommodate those trends, and to account for extrapolation of upstream convection in eastern MT. Trends in radar imagery support the MT convection reaching west central and northwestern ND close to 05 UTC, likely focused on the immediate cool side of a frontal zone that has sharpened in northwestern ND this evening amid a few-hour period of relatively-enhanced cold air advection. Midlevel winds are increasing in that region, and forecast effective shear magnitudes on the order of 45 kt will support organized storms, predominantly of a clustered/linear mode given a large parallel component of deep-layer wind fields to the low- and midlevel front. Forecast soundings suggest effective inflow layers will be elevated overnight with MUCAPE on the order of 1000 J/kg. The primary source of uncertainty in overall severe storm potential stems from disparate model simulations regarding the depth of low-level moisture, which in turn has implications for the magnitude of MUCIN that will be present. Recent HRRR runs have minimized MUCIN in northwestern ND, whereas the 00 UTC NAM portrays around -100 J/kg of MUCIN through the night in deference to a restrained risk. Thus, we will continue to advertise a chance of severe storms, but there remains some doubt in the strength of overnight convection in the northwest. UPDATE Issued at 628 PM CDT Sat Jun 27 2020 The forecast is on track so only minor adjustments were made with this update based on recent trends. As of 23 UTC, a surface trough and related wind shift extending from near Sherwood to New Town, Killdeer, Belfield, and Marmarth continues to serve as the genesis region for high-based thunderstorm activity. Steep lapse rates are supporting MLCAPE on the order of 1000 J/kg, but weak wind fields aloft are both minimizing the severe-storm risk and also making it difficult for these cells to propagate off the boundary. Increasing MLCIN for boundary-layer based parcels between 00 and 02 UTC will result in quick cessation of this initial activity. An additional risk of storms is still expected overnight in northwestern ND. && .SHORT TERM...(This afternoon through Sunday night) Issued at 231 PM CDT Sat Jun 27 2020 Increasing chances for strong to severe storms across portions of the west highlights the most pressing short term forecast challenge. A broad longwave trough draped across the northwestern US will slowly approach the region and amplify as a blocking pattern sets up across the eastern US. As heights begin to fall tonight across the northwest, a shortwave will rotate into northeastern Montana, nudging briefly into northwestern North Dakota, and finally into Saskatchewan. Along a surface trough across the west, a few pop up showers or storms may form late this afternoon and evening if they can break through a bit of a cap. This activity will be diurnally driven and weaken with the loss of heating rather quickly. However, later tonight the aforementioned shortwave will approach the northwest after sunset. This wave may be accompanied by a complex of strong to marginally severe thunderstorms as it clips the far northwest overnight, interacting with the stationary front/pressure trough. On Sunday, a stronger shortwave will rotate around the amplifying west coast trough as it nudges closer. Another complex of strong to severe thunderstorms may accompany this shortwave as it interacts with the same stationary boundary, now a bit further east. Timing will once again be late (after 10 pm local time) but strong elevated instability and sufficient deep layer shear will lend the potential for some severe hail and/or damaging wind gusts. Some of the latest guidance has this activity transitioning into bowing structures by the time it reaches the west out of Montana, and if this were to verify, a more significant wind damage threat could emerge, but confidence is still very low regarding such a scenario. Another hot day is in store for Sunday for almost everyone except the far northwest. Most other places will see continued highs in the upper 80s to mid 90s. .LONG TERM...(Monday through Saturday) Issued at 231 PM CDT Sat Jun 27 2020 Above normal temperatures and continued active weather highlights the long term forecast period. A strong thermal ridge at 850mb builds in on Monday, with the axis centered over the central part of the state by 00z Tuesday. This will lead to another hot day Monday with widespread highs in the mid to upper 90s. Accompanying the heat will be high humidity with dewpoints into the upper 60s to lower 70s. This combination may lead to a few hours of scattered apparent temperature readings over 100 degrees, mainly in the central part of the state and the southern James River Valley. Multiple shortwaves, each one progressively a bit stronger than the last, continue to rotate through portions of the state Monday evening through Wednesday morning, making for a very active pattern with widespread chances of thunderstorms, some possibly severe. SPC has placed almost all of western and central North Dakota in a marginal risk for severe weather on Monday in their latest Day 3 Convective Outlook. Additionally they have placed much of the same area in a 15% contour on their Day 4 Outlook on Tuesday. While the best shear and CAPE doesn`t always appear to lineup optimally, it seems reasonable that at least some organized severe weather looks possible during the Monday night through Tuesday night time frame. The best chance for widespread rainfall looks to be on Tuesday and Tuesday night. The favored area for the most rainfall will be across the northern half of the state, but most everyone should have a shot at a thunderstorm or two during this time frame. Things start to quiet down midweek as some upper level ridging tries to build back in, reinforcing the western US trough. As the trough begins to try and nudge east again, we may see another active period start up again towards the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 941 PM CDT Sat Jun 27 2020 Overnight a cluster of showers and thunderstorms will likely move out of Montana and across west central and northwestern ND, with potential impacts at KXWA. MVFR ceilings in stratus could also impact northwestern ND late tonight and Sunday morning behind that activity and near a weak frontal zone. That front could serve as the focus for more thunderstorms late Sunday afternoon in western ND, but most likely beyond the valid time of the 00 UTC TAF cycle. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CJS SHORT TERM...ZH LONG TERM...ZH AVIATION...CJS
Area Forecast Discussion
National Weather Service Birmingham AL
556 PM CDT Sat Jun 27 2020 .UPDATE... For 00Z Aviation. && .SHORT TERM... /Updated at 0310 PM CDT Sat Jun 27 2020/ Through Sunday. A moist, unstable airmass has been present across the Lower MS Valley for the majority of the morning characterized by dewpoints in the lower to mid 70s and resultant MLCAPE ~3000 J/kg. Scattered thunderstorms are expected to develop over Mississippi and western portions of Alabama throughout the afternoon, downstream of a weak mid/upper level trough embedded in the westerly flow of the low- level ridge centered over the Florida Peninsula. Already beginning to see thunderstorms firing across northern Alabama producing frequent lightning, gusty winds, and pea size hail. A layer of dry air was measured on both the latest 12Z BMX and JAN soundings particularly from 850mb to 675mb which continues to advect northeastward across Mississippi and mix with the sufficient moisture present throughout the column. This has lead to DCAPE values ~1000-1200 J/kg just to the west of the forecast area which will continue to work eastward into Central AL. Eff. bulk shear is a meager 15-20 kts per RAP mesoanalysis, but is enough to help provide some organization to thunderstorm updrafts given the large amount of instability. Based on these conditions, microbursts may occur in any stronger storms that develop today. Will continue the Marginal Risk of isolated severe storms through 9 PM for damaging winds up to 60 mph. A more robust storm may contain large hail up to quarter size, but this is not the primary threat due to relatively unfavorable mid- level lapse rates. Any lingering thunderstorms should become primarily outflow driven by late afternoon/early evening, eventually waning in intensity over the eastern half of the forecast area with the loss of daytime heating. Some clearing in the clouds may occur overnight as the mid- level impulse moves over Georgia. At daybreak, there may also be areas of patchy fog due to low dewpoint depressions, but this will quickly mix out after sunrise. Rain chances are much lower tomorrow as mid-level ridging takes control, but this means afternoon highs will be back in the lower 90s for most of the area. 86 .LONG TERM... /Updated at 0310 PM CDT Sat Jun 27 2020/ Sunday night through Friday. Next week Alabama will be transitioning through several upper level pattern changes. The first half of the week the upper flow pattern will be characterized by a building omega block pattern with an upper trof over the Plains States and another upper trof over the mid-Atlantic region. In between the two trofs will be an upper ridge across the Lower and Middle Mississippi Valley regions. Increasing heights over Alabama will result in warmer afternoon temperatures with a tropical air mass trapped underneath. The combination of heat and humidity will produce heat indices of 100-103 degrees Monday and Tuesday. Despite the presence of a ridge, scattered to numerous showers and storms will develop each day Monday and Tuesday, with better coverage on Tuesday. By Wednesday, the East Coast trof will begin to dig southward and southwestward, back-building into Alabama. The developing trofiness will result in cooler daytime temperatures and high rain chances for the period Wednesday through Friday, mainly in the afternoons. 58/rose Previous long-term discussion: /Updated at 0238 AM CDT Sat Jun 27 2020/ Sunday night through Friday. An omega block will be present over the northern CONUS and Canada for the first half of the week, with an upper high briefly closing off over northern Ontario and troughs over the western and northeastern CONUS. Meanwhile a subtropical ridge will retrograde westward across the Gulf to Mexico. Ridging will strengthen over the Plains and Rockies late in the week, allowing weak troughing over the eastern CONUS. Several convective generated/augmented waves will eject from the western CONUS trough through mid week, undercutting the Great Lakes/Ontario ridge and interacting with a moist and unstable air mass to result in an unsettled pattern across the Deep South. Ridging and dry air aloft should result in mainly dry conditions Sunday night. A lead shortwave will eject across northern Mississippi on Monday, flattening the 500mb flow across Central Alabama, however the surface to 700mb flow will remain anticyclonic and 850-700mb mean RH will be somewhat limited. Ample instability and boundary layer moisture will be present for shower and thunderstorm development, but the above factors will probably keep activity widely scattered. The lower coverage of convection compared to the rest of the week will cause Monday to have the highest heat index values of the week, maxing out around 100 to 103 degrees. Ridging will weaken on Tuesday as flow becomes westerly to southwesterly ahead of a shortwave over the Ozarks and Mid-South. PWATs around 1.9 inches and plentiful instability will allow scattered to numerous showers and storms to develop Tuesday afternoon. Flow aloft will become northwesterly Tuesday night through the rest of the week. Disturbances in the northwest flow and PWATs around 2 inches will result in enhanced rain chances, and keep highs mainly just below 90 degrees. Guidance is hinting at the potential for one or more MCSs impacting portions of the Deep South during this period, though confidence in any details is low. Severe weather potential with these is unclear, but at minimum expect daily risks of strong storms. 32/Davis && .AVIATION... 00Z TAF Discussion. Generally VFR conds thru the period. Diurnal isolated convection thru 02z and then again after 20z. Low level winds will remain high enough overnight for isentropic lift to form MVFR cigs across the northern TAF sites between 10z and 14z. The cigs should scatter by 15z, with sct cumulus after 15z. 58/rose && .FIRE WEATHER... Warm and humid conditions continue for the next few days, with scattered showers and thunderstorms, especially during the afternoon and early evening hours. Minimum relative humidity values will mainly remain above 55 percent. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 69 91 70 90 72 / 30 30 20 40 20 Anniston 70 90 70 90 73 / 30 20 20 40 20 Birmingham 71 91 73 92 74 / 30 20 10 40 20 Tuscaloosa 70 91 73 93 75 / 30 20 10 30 20 Calera 70 91 72 91 74 / 30 20 10 30 20 Auburn 71 90 71 90 73 / 30 20 10 30 20 Montgomery 73 93 73 93 74 / 30 30 10 30 20 Troy 72 94 72 93 75 / 30 30 10 30 20 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$
Area Forecast Discussion
National Weather Service Denver/Boulder CO
847 PM MDT Sat Jun 27 2020 .UPDATE... Issued at 843 PM MDT Sat Jun 27 2020 Update to the forecast this evening to bring temperature trends in line with observed, which are already very close, and to help ease the pops out on the far eastern plains. Line of thunderstorms have exited the forecast area and are into western Kansas. Anvil debris from this afternoon`s showers and thunderstorms will give way to mostly clear skies overnight. && .SHORT TERM...(This evening through Sunday) Issued at 233 PM MDT Sat Jun 27 2020 A weak upper trough is currently pushing east across the state, allowing for thunderstorms to form. Precipitable water values continue to be about one third of an inch below yesterday`s values. Therefore storms today will be more of the high based gusty variety. Higher dewpoints out near the eastern border will allow for a higher hail threat. A boundary over Lincoln County along with a stream of storms moving up from the southwest should bring most of the activity near there later this afternoon. As the backside of the trough moves overhead later this evening, convective activity is expected to die off quickly, with not much around after 8pm. HRRR continues to show some echoes overnight, but not buying it at this time with the subsidence on the backside. Gusty winds along the foothills will again occur tonight as a surface lee trough continues to deepen in response to a large upper trough dropping into the Pacific Northwest. The gusty downslope winds will keep minimum temperatures mild. Southwesterly flow aloft will increase Sunday, bringing in warmer and drier air at mid and upper levels. Maximum temperature readings should be about 5 degrees warmer over today`s readings, with some 100`s not out of the question over the eastern plains. A deepening surface trough is expected to form into a surface low over southeastern CO later in the afternoon however, so higher dewpoints are expected to be pulled in over the northern plains and urban corridor. Therefore, expecting more isolated to scattered thunderstorms again tomorrow, again with high bases and gusty winds. Less CAPE is expected tomorrow, so no severe strength storms are expected. .LONG TERM...(Sunday night through Saturday) Issued at 233 PM MDT Sat Jun 27 2020 For Sunday night into Monday the upper level closed low will be over the intermountain west digging southeast extending a broad trough into the Great Basin through the day Monday. This upper level pattern will increase southwest flow over the state. Closer to the surface a deepening lee side low will further increase drier southwest winds to push into the eastern plains with a general eastern progression pulling winds westerly by the afternoon hours. This will keep humidity levels low so will help to keep storms at bay but on the flip side will increase fire weather concerns with reduced RH levels. As mentioned in the previous discussion the biggest question mark currently continues to be the winds. Timing will be important with models bringing the upper jet around the base of the trough and into western colorado by the late afternoon/early evening. At this time winds in the mid and upper levels are ranging from 15 to 35 kts which with adequate mixing could translate to winds at the surface possibly gusting in the 20 to 25 mph range which is borderline for fire weather highlights. Especially combined with precipitation that fell over the last 48 hours across much of the area. This will need to be monitored along with local fuels to determine if a Red Flag will be needed even with the marginal winds. For Tuesday, the upper low will push north into the northern rockies with a negatively tilted shortwave trough moving into western Colorado during the day. At this time the models are showing the upper trough pushing through during the late afternoon hours with a cold front dropping down from the south during the morning. This could help to increase some northeast to easterly flow at the surface behind it for the afternoon albeit a tad weak. This will help to provide some lift along the base of the foothills for storm initiation. Timing of the trough passage will be important because if it were to push through earlier in the day then flow will turn more downsloping and subsident making storm initiation difficult. Will stick with the former solution for now as models are showing some consistency here. Overall, parameters are not looking robust, however models do tend to over mix the lower levels so still a possibility that CAPE will increase with model updates and there is already good deep layer shear of 50 to 65 kts. Will maintain higher pops for the afternoon timeframe. On Wednesday models show the upper trough pushing east and being replaced with ridging that will bring dry conditions to the region. Temperatures will be slightly cooler in the post frontal airmass on Wednesday with highs in the lower 80s. Weather will be slightly benign for the remainder of the week with a slight chance of diurnal convection each day with warming temperatures. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 545 PM MDT Sat Jun 27 2020 VFR through the period with scattered showers and thunderstorms after about 20z Sunday for all terminals. Tricky wind forecast at KDEN with northerly environmental flow and thunderstorm outflow wind coming up from the south. Appears outflow has stalled & went with northerly flow for first couple hours of TAF period. Wind to settle down to south to southwesterly after 02z and remain for the rest of the night. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Hanson SHORT TERM...Kriederman LONG TERM...Bowen AVIATION...Hanson
Area Forecast Discussion
National Weather Service Boston/Norton MA
1021 PM EDT Sat Jun 27 2020 .SYNOPSIS... Low pressure over the lower Hudson Valley will move east off the coast of Southern New England early tonight, with steady rains coming to an end and improving conditions overnight. Warm and humid weather ahead of an upper-level disturbance will spark thunderstorms later in the day Sunday, and few may become strong to severe. Slightly cooler than average temperatures along with pop-up afternoon/early evening showers during the first half of next week. Drier trend is expected for the second half of next week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Mostly tweaks to the ongoing forecast for tonight. Widespread showers have moved off the coast. Attention now turns to another area of showers across upstate NY. These exhibited a weakening trend as they moved southeast this evening. Not sure how much will hold together to cross the Berkshires, just yet. Will be monitoring the progress of this area overnight. Brought temperatures back in line with observed trends. As of this writing, a weak mesolow was centered around New Bedford. This mesolow will move farther offshore after midnight, dragging slightly less humid air farther southeast. This should not last long with a warm front to our south poised to push north late tonight. Adjusted rainfall chances for the rest of tonight. An consensus blend of a HRRR ensemble and NationalBlend best reflected current thinking and timing. Previous Discussion... Latest observations indicate surface low along the CT/RI border. This surface wave and its rain shield will continue to slowly move east this evening with a drying trend to follow. Not much of an airmass change behind the low so expecting seasonable temps overnight with lows in the low to mid 60s along with dew pts in the same range. This may yield some patchy fog. Light WNW flow and associated subsidence behind the departing low should be sufficient for decreasing clouds second half of the night with at least partial clearing by sunrise Sunday. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... Sunday: ** Scattered strong to severe thunderstorms possible Sunday ** Any overnight to early morning mist or fog will burn off shortly after sunrise. Mostly sunny conditions are then expected through most of the morning into the mid-afternoon with a continued humid air mass (dewpoints in the mid to upper 60s). This will help destabilize the atmosphere, as we await the approach of a shortwave trough seen in the Simple Water Vapor RGB product as of early- afternoon Saturday north of Lake Superior. It`s this feature and its associated cold frontal boundary that will interact with the building convective instability to help fire thunderstorms especially later in the day (mid-afternoon to mid-evening). By early afternoon, it`s anticipated that convective temperatures should be reached with any convective inhibition gone. Most-unstable CAPE values are expected to range in the 1500-2500 J/kg, boosted by mid-level lapse rates in the 6-6.5 C/km range. Outside of the terrain and possibly on the western side of any sea-breezes, there isn`t much to trigger thunderstorms. That changes by mid- to late- afternoon with the approach of the shortwave trough, which most models have digging southeastward into central/eastern NY. This should generate scattered thunderstorms, and a few of these are expected to become strong to severe. Areas in western and central MA into northern CT and northern RI would appear to have the best shot at seeing stronger thunderstorms given the late-day timing of the cold front. Such a threat could extend all the way to the coast of eastern MA but is more conditional on the frontal timing being faster than currently progged or if the sea-breeze can ignite thunderstorms during the early to mid-afternoon. The bigger limiting factor to Sunday`s severe convective setup is that mid-level winds are fairly weak, resulting in effective bulk shear magnitudes in the 25-35 kt range. This support pulse to loosely-organized updrafts. The strongly heated low-levels with inverted-V profiles indicated in model soundings support fairly sizable downdraft-CAPE values, leading to a primary severe threat of strong to locally damaging winds. Hail would be a secondary concern, and while sub-severe hailstones would be more likely, a few 1" in diameter could be possible with the lapse rates being somewhat steeper than moist- adiabatic. Though isolated storms before this time could be possible if sea breezes or terrain can get storms going, an approximate storm timing looks to be between 3 and 8 PM. SPC has maintained the Marginal Risk/5% severe probabilities, but locally I`ve also added enhanced wording in the forecast for gusty winds and small hail. Activity should be clearing central and western MA and Hartford/Tolland Counties in CT by early evening, but may still be ongoing across eastern MA. Highs should reach the mid to upper 80s in the interior, with upper 70s to lower 80s near the coast and across the Cape. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... Highlights. * Isolated chance of diurnal showers and thunderstorms though the middle part of next week. * Cooler than average temperatures through Wednesday, followed by a seasonably warm afternoon on Thursday. Big Picture... As previously discussed; an omega blocking pattern will develop with a weak area of low pressure over New England Sunday night into early next week. At the mid-levels a trough will extend down towards the Mid Atlantic before becoming a mid-level cut-off area of low pressure. Model guidance suggests that mid-level low will remain stationary over New England for the majority of the upcoming week. Expect periods of unsettled weather into late-week, after that, the jet should kick the mid-level low out to sea. Sunday night through Monday... High-res models suggest a few isolated showers could linger overnight, with an isolated thunderstorm across the Cape or Islands. With the front left quadrant of the jet over western CT/MA, positive vorticity advection could aid in generating pop-up showers Monday afternoon. Additionally, PWATs values will remain in the ballpark of 1.50". Temperatures will be noticeably cooler as well. A light north to northeasterly wind direction will limit our daytime heating. From Cape Ann to Cape Cod and the Islands the afternoon high might not get out of the 60s. Inland temperatures have a better shot of reaching the middle 70s - with the highest temperatures in the low- 80s from Hartford to Springfield. Tuesday through Friday... Cooler than normal temperatures will prevail Tuesday and Wednesday as easterly winds at 925mb advect cooler air from the Gulf of Maine. A recent buoy observations show that the sea surface temperature are between 62F-67F. Coastal communities from Cape Ann could struggle to get out of the 60s, while the Cape and Islands reach the low 70s. Further inland temperatures will still be cooler than normal with highs reaching the middle and upper-70s; with the exception of the Connecticut River Valley - there highs are expected to reach the lower-80s. Diurnal heating will once again aid in the propagation of afternoon showers and isolated thunderstorms. We don`t expect a "washout", but, isolated heavy rain is possible with these isolated thunderstorms. Moving into Thursday, likely the warmest day of the week, temperatures could return to the lower and middle 80s; a few upper 80s are possible across the Connecticut River Valley. And once again afternoon showers and storms will likely develop as a result of the daytime heating. Friday the mid-level low begins to breakdown and move east. Higher pressure from the west will begin to slide in from the northern Great Lakes region. This will help to dry out Southern New England. 925mb wind is once again from the east and will help keep temperatures cooler, for many highs only reach the low and middle- 70s. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tonight: Moderate confidence. Mainly MVFR central/eastern TAFs as a weak low pressure passes offshore. The question mark for tonight is with light progged winds and the ground being wettened, and if that is enough to spread patchy mist or fog to areas beyond just the favored locations. I show some 4-6 SM mist at times, but confidence in timing and development is low. Winds become light northerly tonight except continued southerlies across the Cape. By daybreak, winds should be from the SW 4-8 kt. Sunday: High confidence. Any fog or mist burns off shortly after sunrise to VFR thru mid-afternoon. Scattered thunderstorms, some potentially strong to severe, will develop around mid-afternoon across the Berkshires and progress eastward towards the coast through late-afternoon/early evening. Local MVFR/IFR visibility possible along with gusty winds and small hail. Will carry as a period of VCSH for now but could see a need for VCTS with later TAF issuances. Should have sea-breeze develop at BOS, but otherwise winds SW 4-8 kt. Sunday Night: High confidence. SHRA/TSRA and their local restrictions may still be lingering around until 03z especially east, but should be returning to VFR thereafter all terminals. Winds become NW/NNW. KBOS Terminal...High confidence in TAF trends. Moderate confidence in timing. KBDL Terminal...High confidence in TAF trends. Moderate confidence in timing. Outlook /Sunday Night through Thursday/... Sunday Night: Mainly VFR, with areas MVFR possible. Chance SHRA, slight chance TSRA, patchy BR. Monday: Mainly VFR, with areas MVFR possible. Chance SHRA, chance TSRA. Monday Night: Mainly VFR, with areas MVFR possible. Slight chance SHRA. Tuesday: Mainly VFR, with areas MVFR possible. Chance SHRA, chance TSRA. Tuesday Night through Wednesday: Mainly MVFR, with areas VFR possible. Chance SHRA, chance TSRA. Wednesday Night: Mainly VFR, with areas MVFR possible. Chance SHRA. Thursday: VFR. Chance SHRA, chance TSRA. && .MARINE... Increasing southwest winds later tonight along with a southwest fetch will cause winds and seas to rise to lower-end Small Craft Advisory levels on the southern waters tonight. Low clouds and patchy fog overnight, with fog possibly reducing visibility to 3 NM or less. Any fog should burn off early Sunday. Rough seas should continue on most of the southern waters early Sunday, diminishing below 5 feet around noontime. Thunderstorms are possible late tomorrow afternoon into early evening. Outlook /Sunday Night through Thursday/... Sunday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, slight chance of thunderstorms, patchy fog. Monday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers, chance of thunderstorms. Monday Night through Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Tuesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers. 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. Chance of rain showers, slight chance of thunderstorms. Thursday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, chance of thunderstorms. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until noon EDT Sunday for ANZ255. Small Craft Advisory until 7 AM EDT Sunday for ANZ235-254. Small Craft Advisory until 5 AM EDT Sunday for ANZ237. Small Craft Advisory until 10 AM EDT Sunday for ANZ256. && $$ SYNOPSIS...Loconto/Gaucher NEAR TERM...Belk/Nocera/Loconto SHORT TERM...Loconto LONG TERM...Gaucher AVIATION...Belk/Nocera/Loconto/Gaucher MARINE...Belk/Loconto/Gaucher
Area Forecast Discussion
National Weather Service Buffalo NY
1032 PM EDT Sat Jun 27 2020 .SYNOPSIS... A weak cold front will cross the area tonight and produce a few showers and thunderstorms. High pressure will then build into the Great Lakes region with mainly dry conditions, although a few stray showers or a thunderstorm cannot be ruled out, especially east of Lake Ontario. A warming trend then ensues for most of next week into the holiday weekend. && .NEAR TERM /THROUGH SUNDAY/... Radar imagery late this evening showing a few linear clusters of thunderstorms along a weak trough axis stretching from near Toronto to the Tug Hill at 0230Z. This weak low level trough, and an approaching mid level trough will cross the region overnight and continue to support a few showers and storms. Latest 00Z NAM based high-res CAMS guidance and HRRR continue to suggest maintenance of this broken band of convection as the trough crosses the region. This will bring a few showers and thunderstorms to much of the region overnight with uneven coverage of rainfall. Most of the updrafts have lost their intensity compared to early this evening. A few storms may contain brief downpours, gusty winds, and small hail but no severe weather is expected. Most of this should be ending by daybreak, with just a few leftover showers moving into the Finger Lakes and Central NY. Lows will drop back into the mid 60s in most areas, and around 60 in the Southern Tier valleys and Lewis County. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... The sprawling upper low over Quebec, around which the trough for tonight is pinwheeling, will gradually shift southward toward New England and off the coast of the Middle Atlantic state, before finally ejecting beyond mid-week. It will make its closest pass to the eastern portion of our CWA on Tuesday, which will result in a better chance of daytime showers and thunderstorms over the North Country that day. Otherwise, most shower and storm activity will be driven by lake breeze processes and terrain enhancement as riding attempts to continually make inroads into the CWA through the first half of the week. This will result in temperatures across WNY being a good deal warmer than locations to the east of our CWA, with even warmer air poised to make a triumphant return to the entirety of the northeastern US in the long term period. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... A closed low, will remain over the Northeast Wednesday before joining back into the longwave pattern Wednesday night and Thursday. Otherwise, a rather weak and poleward orientated omega block in the upper levels will set up across Canada and Northern United States/Canadian border for the remainder of the work week before shifting towards a blocking high pattern across the CONUS. Associated with the closed low on Wednesday there will be chances for showers and thunderstorms across eastern NY due to a deeper source of moisture. That being said, the best chances for shower activity will lie east of the Finger Lakes region and span up into the North Country. That said, the Western New York region will the lowest chances of rain. Weak surface high pressure will set up over the region for the remainder of the work week which will promote a few days of dry weather. The start of the holiday weekend will be associated in the shift of longwave blocking patterns which will promote the chances for showers and storms. Temperatures throughout the time period will range in the 80s. The omega blocking pattern in the later half of the work week will promote 850mb temperatures to soar into the upper teens Celsius and near 20C, which will assist the day time highs to be in the upper 80s Thursday and Friday. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... A weak cold front and upper level trough will cross the eastern Great Lakes tonight, continuing to support a few showers and storms. Scattered to numerous thunderstorms will continue southeast of Lake Ontario through the rest of the evening with local/brief MVFR to IFR conditions. Overnight another round of scattered to numerous showers and thunderstorms is expected to cross Western NY, also with local/brief MVFR to IFR conditions. Most of this will taper off late tonight, with just a few scattered showers left by daybreak across the western Finger Lakes and Central NY. Areas of MVFR/IFR CIGS will develop late tonight through Sunday morning, with IFR favored across the higher terrain. The low CIGS will scatter out by mid to late morning Sunday, leaving mainly VFR for the remainder of the day. Cumulus fields with bases on the 4-6K foot range will develop from midday through the afternoon. A few scattered showers or isolated thunderstorms are also possible with sparse coverage. The best chance of this will be east of Lake Ontario. Outlook... Sunday night through Thursday...mainly VFR with a small chance of showers at times, especially east of Lake Ontario. && .MARINE... A trough and weak cold front will cross the eastern Great Lakes tonight with a few showers and storms with locally gusty winds. Otherwise, light winds and lower chances of thunderstorms will characterize most of next week on the lakes. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...Fries/Hitchcock NEAR TERM...Hitchcock SHORT TERM...Fries LONG TERM...EAJ AVIATION...Hitchcock MARINE...Fries/Hitchcock
Area Forecast Discussion
National Weather Service Caribou ME
915 PM EDT Sat Jun 27 2020 .SYNOPSIS... An upper low will move into New England with a series of disturbances moving across Maine this weekend into early next week. High pressure approaches the region late next week. && .NEAR TERM /THROUGH SUNDAY/... 9:15 pm update: Area radars indicate widely scattered showers from the Katahdin Region north. No recent lightning strikes and GLM upstream not indicating any in cloud electrical activity. Can`t rule out completely that there will not be a lightning strike, but odds appear low. The main update at this time was to the PoPs and weather for the remainder of the night based on the latest radar trends and current observations. Previous discussion: Heating this afternoon has helped destabilize things for some isolated convection to fire up, but nothing substantial. Weak s/wv ridging shown nicely at 850mbs has aided in suppressing organized convection. Activity appears to be diurnally driven and should wind down w/the loss of heating this evening. Watching upper trof back across the Ottawa and Ontario region w/some convection firing up. This upper trof is picked up well by the latest HRRR and RAP as well as the GFS and is shown by the guidance to push into the region tonight. This feature will allow for more showers and the potential for some tstms up through midnight. The strongest storms will be this evening and weaken overnight. Will not include any enhanced wording as convective parameters weaken. Mdl soundings do show PWs climbing to near 1.5" which would favor some heavy rainfall. Activity looks like it will end sometime after midnight w/the loss of substantial forcing. The GFS and NAM show some more shower activity moving into wrn and nwrn areas by early morning hrs Sunday. There does appear to be some vorticity advection which will help trigger the showers. Rainfall amounts will be light. At the same time, weak low pres will be passing off the srn New England coast, w/any measurable rainfall remaining offshore. There is the threat for some patchy fog overnight, especially for areas that received rainfall. Any morning fog will burn off pretty quick. The upper low in Canada is expected to drop s into the state on Sunday. Cold pocket aloft combined with diurnal heating will allow for destabilization and showers to develop. Convective parameters are not that impressive and shear is looking weak. The NAM looks like it is overloading the dewpoints and ramping up the moisture. Followed closer to the GFS and show the best convective potential to be across the far w and nw. This means CAPE of 400-700 joules w/shear < 10 kts. Activity will slowly slide east during the afternoon moving into eastern areas by later in the day. Again, any significant threat would be heavy rainfall. Backed off the model QPF as it looks to be running too high due to convective feedback. Afternoon high temps will be dependent on cloud cover and extent. Stayed close to the previous thinking of 70s to around 80F. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... Upper level low continues to drop south from Quebec the short term period. This will keep an unsettled weather pattern across the region through the period, with mainly afternoon showers expected through the period. The cold pool aloft and diurnal instability warrants keeping mention of slight chance of afternoon thunderstorms each afternoon. More in the way of cloud cover will result in afternoon high temperatures primarily remaining in the 70s, which is near normal for this time of year. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... The aforementioned upper low will continue to dominate the weather Tuesday night through Wednesday with continued, mainly afternoon showers and thunderstorms. The upper low finally kicks out to the Southeast of the area Wednesday night. A short wave and associated cold front will cross the region on Thursday. Somewhat cooler and drier air will follow for late next week into next weekend. Temperatures will be above normal Wednesday and Thursday, and then near normal late next week into next weekend. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... NEAR TERM: Fog possible overnight for KBHB w/conditions dropping to MVFR and then down to IFR/LIFR by Sunday morning. Some of this could work its way up into KBGR by early Sunday morning. Conditions should improve to VFR by midday. Elsewhere, VFR right into Sunday outside of any patchy late night fog. SHORT TERM: Mainly VFR, except MVFR will be possible in scattered showers and thunderstorms, mainly during the afternoon Mon thru Thu. For KBGR/KBHB IFR will be possible at night and early morning in low clouds and patchy fog. && .MARINE... NEAR TERM: Fog remains the concern overnight into Sunday morning. Some of high resolution guidance has been overdoing the fog as of late. Decided to lean w/patchy fog overnight and keep vsbys 1 to 3 NM. SSW winds around 10 kts tonight will shift to the S on Sunday w/a slight increase in speed. Seas will remain at 2-3 ft. SHORT TERM: Winds/seas will remain below SCA levels through the period. Visibilities will be reduced in patchy fog through mid week. && .CLIMATE... Today, June 27, 2020, marked the 12th consecutive day with a high of 80 degrees (F) or warmer in Caribou, Maine. This breaks the record for the most consecutive days with a high of 80 degrees or warmer in Caribou. The old record of 11 days, was established yesterday. Prior to yesterday, the record was 10 days from August 14-23, 2015. Weather records in Caribou date back to 1939. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...CB/Hewitt Short Term...Duda Long Term...Duda Aviation...CB/Hewitt/Duda Marine...CB/Hewitt/Duda Climate...CB
Area Forecast Discussion
National Weather Service Cleveland OH
1008 PM EDT Sat Jun 27 2020 .SYNOPSIS... A cold front will move across the area tonight and Sunday. It will settle across southwest Ohio. High pressure will nudge southward across the Upper Ohio Valley and largely remain across the area this upcoming week. && .NEAR TERM /THROUGH SUNDAY NIGHT/... Band of thunderstorms over Lake Erie has been back building across the western basin along the slow moving cold front. Raised pops for our northwest tier of counties as it will likely make it at least that far before starting to break up. Thunderstorms are producing frequent lightning, heavy rain, and wind gusts to around 30+ mph. HRRR has been showing at least scattered showers holding together as the front crosses NE Ohio during the overnight hours so will continue with chance pops. Temperatures have also been holding up pretty warm with some locations still in the upper 70s to near 80 degrees in Toledo. Raised mins for tonight given the high dewpoints with cold advection largely delayed until after 12Z. Stratus is expected to fill in overnight and cannot rule out some patchy fog if lower ceilings develop. Previous discussion... As of mid afternoon the cold front was located across lower Michigan. Convective activity has been focused across central Ohio with the MCV that moved out of central IN this morning. Much of northern OH has been void of convection this afternoon in the stabilizing wake of the central OH complex. That being said, we still have the cold front to pass so cannot rule out a shower/thunderstorm. Dewpoints will be slow to lower and tonight will be muggy. Lows will only fall back to the mid/upper 60s. High pressure begins to build southward across the eastern Great Lakes for Sunday. Will maintain some mention of showers/thunderstorms across the southern half of the area for Sunday, but expect most of the area to be dry. The cold front will likely be along the south shore of the lake early Sunday morning and will continue to press south. Highs will still be seasonable. Sunday night the front pushes far enough south to push shower/thunderstorm chances south of the area. We may even have a couple upper 50s for lows across far eastern OH/inland nw PA. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... Confidence increasing in omega block pattern setting up over the region with an upper-level ridge over the Midwest/Great Lakes area and an upper-level low situated over the northeast CONUS through the week. On Monday and Tuesday, a surface front lingers across southern Ohio and portions of Indiana. Instability during the afternoon will result in isolated thunderstorm during the afternoon. Otherwise, mostly to partly sunny skies with highs in the 80s and lows in the 60s will occur through the short term period. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... Omega blocking pattern continues through the long term period with a similar forecast as the short term period in mind: Isolated showers and thunderstorms daily in the afternoon with highs in the 80s and lows in the 60s. Hottest days expected to be on Thursday/Friday where high temperatures could get into the upper 80s with a few locations touching 90. && .AVIATION /00Z Sunday THROUGH Thursday/... At 8 PM, a cold front was located near the north shore of Lake Erie with a line of thunderstorms sinking slowly south. These thunderstorms may impact TOL or CLE through 04Z, but could also weaken as they settle south across Lake Erie. Will monitor the need to add thunderstorms to CLE TAF. Elsewhere showers and thunderstorms are struggling to develop but could see a stray showers at MFD/CAK/YNG/ERI overnight as the front settles south. Have left out of the terminals for now as coverage is expected to be low. As the front arrives later tonight, expecting to see an expanding stratus cloud deck. MVFR ceilings are likely with pockets of IFR also possible in the 09-12Z window. Surface moisture remains which will also contribute to MVFR visibilities. Ceilings and visibilities will tend to improve towards midday as drier air arrives behind the front. Southwest winds ahead of the front will shift to the north or northwest behind the front overnight into Sunday morning but will generally be 10 knots or less. Outlook...Non-VFR possible early Monday morning across eastern OH. && .MARINE... Southwest winds of 10 to 15 knots continues through the evening and early tonight before the cold front moves south across Lake Erie tonight. Relatively quiet conditions are expected through the remainder of the forecast as a weak pressure gradient sets up over Lake Erie for awhile. Winds expected to be predominantly northeast Tuesday through Wednesday, though sustained winds should generally be 10 knots or less, so no major impacts are expected. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...Oudeman NEAR TERM...KEC/Oudeman SHORT TERM...Saunders LONG TERM...Saunders AVIATION...KEC MARINE...Saunders
Area Forecast Discussion
National Weather Service State College PA
1137 PM EDT Sat Jun 27 2020 .SYNOPSIS... An upper level trough will push across the region this weekend, pushing a cold front through the state on Sunday. A drier and less humid pattern early next week should trend more unsettled heading into July with temperatures remaining near to above daily climate averages. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Late evening water vapor loop shows one shortwave exiting eastern Pa and another upstream over southern Ontario. Loss of heating and passage of first shortwave has caused lingering showers over southern Pa to die out late this evening. Focus is now on the northern tier counties late tonight, where arrival of second shortwave could produce a late night shower or storm in spots. RAP and earlier HREF both indicate MUCAPES near 1000 j/kg over the northern tier even late tonight. Model soundings indicate a very moist southwest flow beneath developing inversion will lead to low clouds late tonight over the Alleghenies. East of the mountains, expect clearing skies, as cirrus shield exits the area this evening. Light wind and clearing skies is likely to promote patchy late night fog into those locations that received appreciable rainfall earlier today, roughly along the I-80 corridor. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... Upper level trough axis and associated surface cold front are progged to push southeast across the region Sunday. A late afternoon fropa favors the best chance of a shower or storm across the southeast counties, while only a slight chance of a morning shower is currently forecast with the morning fropa over the northwest mountains. Moderate northwesterly flow aloft should promote some storm organization and dcapes are quite high, yielding a local risk for gusty/damaging winds with any storms that form over the southeast counties during the afternoon. For the bulk of the CWA on Sunday, dry and partly sunny conditions with slowly lowering dewpoints and a moderate NW breeze of 10-15 kts will provide a pleasant, warm end to the weekend. Max temps will range from the upper 70s across the higher terrain of the north and west, to the upper 80s in the southeast. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... Medium range guidance supports drier and somewhat less humid conditions early next week, as northerly flow develops over Pennsylvania on southwest periphery of upper low over New England. Mean 850mb temps around 16C indicate temperatures are likely to be slightly above average. There are continued indications that upper troughing over northeastern North America will become more pronounced and extend southward into the Mid Atlantic region by the middle of next week. This scenario would result in a renewed chance of scattered, diurnal convection across central Pa Tuesday and Wednesday. Eventually, the latest NAEFS and ECENS push this trough east of Pa by late in the week, as anomalous upper level ridge builds in from the midwest. This supports hotter and more humid conditions to end the week. Scattered, ring of fire convection will remain a possibility across Pa Friday and Saturday on northern periphery of upper ridge. && .AVIATION /04Z SUNDAY THROUGH THURSDAY/... Some adjustments to the TAFS at times this evening. Nothing on the radar now. Earlier discussion below. 00Z TAFS sent. A few showers across the area, but less than I expected last night when I worked. Aside from the showers, the main issue later tonight and early Sunday morning will be low CIGS. Expect conditions to improve by late morning. Left showers out of the forecast for now. Dry weather for Monday into at least Tuesday, if not early Wednesday. Outlook... Sun...Still a chance of showers and storms across the SE third of the state. Mon...A chance of showers and storms, mainly south. Tue...Mainly dry with VFR conditions. Wed...Chance of showers and thunderstorms. Thu...Still a chance of showers and thunderstorms. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert/Steinbugl NEAR TERM...Fitzgerald SHORT TERM...Lambert/Fitzgerald LONG TERM...Fitzgerald AVIATION...Martin
National Weather Service Kansas City/Pleasant Hill MO
1042 PM CDT Sat Jun 27 2020 .Discussion... Issued at 235 PM CDT SAT JUN 27 2020 A mid-level shortwave/ MCV is moving over the middle of the forecast area this afternoon. Moist ascent on the southern side of this wave and north of a warm front, was leading thick cloud cover from eastern KS through central MO. This cloud cover is really inhibiting destabilization as just southwest of the area, in southern KS, CAPE is already around 4000 J/kg. Models did not initialize the cloud cover well and are struggling with how quickly to destabilize the area this afternoon. The RAP perhaps has the best handle on things and as the cloud cover shifts east and the warm front moves northward from the south, builds the instability northward. As that front is lifting northward, isolated to perhaps scattered showers and storms should develop. This looks most likely late this afternoon through around midnight for the KC area southward and after midnight for northern MO. The chances of severe storms looks rather low at this time. Given the instability that may build northward with the warm front, and the marginal shear, some strong storms can`t be ruled with some hail and gusty winds. Hot and humid conditions will move into the area Sunday. We should see highs in the low to mid 90s with upper 60 to lower 70 degree dewpoints during the heat of the afternoon. That combination should lead to heat index values around 100 across the area. There is also an outside chance that the heat and humidity will be enough to reach convective temperatures, based on NAM forecast soundings. But am more confident we`ll remain capped and stay dry so have no mention of precipitation tomorrow. For the start of the work week, a weak shortwave will lift into the area from the southwest during the afternoon. This may lead to some showers and storms in across areas mainly east of I-35. That wave may linger into Tuesday into Wednesday with additional chances for precipitation. The other story, and probably more likely to occur, is the building heat through the middle of the week. By Wednesday, highs in the middle 90s look likely with heat indices approaching 105 in some places. Temperatures should linger in the low to middle 90s through the end of the week but the upper pattern isn`t as clear cut for heat as one would like to see. The upper ridge is over the area but also weakens on its east with weak troughing over the Southeast. && .Aviation...(For the 06Z TAFS through 06Z Sunday Night) Issued at 1042 PM CDT SAT JUN 27 2020 VFR conditions will persist through much of the next 24 hours. Only issue may be early Sunday morning thunderstorms as a decaying complex of storms moves through eastern Kansas into northern Missouri. Timing for this looks to occur between 09Z and 14Z, as the nose of the low level jet reaches the Kansas Missouri border. Otherwise, expect gusty southerly winds tomorrow. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Discussion...CDB Aviation...Cutter
National Weather Service Hastings NE
951 PM CDT Sat Jun 27 2020 ...Short Term Update... .UPDATE... Issued at 951 PM CDT Sat Jun 27 2020 Various comments about the rest of tonight, mainly regarding thunderstorm chances/possible severe: 1) Especially up until recently, haven`t had the greatest "feel" for how things play out tonight, as if anything "geographic confidence" in thunderstorm placement had been lacking somewhat. That being said, now that the beginning stages of a strong to severe linear mesoscale convective system (MCS) appears to be underway in northwest KS and is tracking east, feel a bit better about the Severe Thunderstorm Watch that SPC earlier coordinated for most of our counties along/south of the state line (officially valid until 3 AM). While this complex is currently expected to be our "main show" overnight, perhaps with the greatest threat being 60-70 MPH winds (and to a bit lesser extent large hail), would also not be surprised to see more "random" strong to severe activity blossom farther north (outside the current Watch area). Unlike last night, where the low level jet exit region was pretty clearly focused in our south, tonight it actually is progged to aim more into our central/northern counties as it veers after midnight. IF storms do get going north of the current watch area, at least sporadic severe hail (up to around half dollar size) could easily materialize given healthy most-unstable CAPE up around 3000 J/kg, although the damaging wind threat would probably not be as high as in our south. Not necessarily sure that possible severe development in our central/northern counties would necessitate a northward expansion of the current Watch, but it`s a possibility that cannot be discounted. 2) On a positive note, if storms are able to fire up north of the current Watch area, some counties that have been VERY DRY of late (such as Adams/Hall/Hamilton etc.) could finally get their shot at a halfway decent rain, but again, this is far from a "sure thing", and that is why rain chances/PoPs have been limited to 50 percent or less in this portions of our coverage area (CWA) for the time being. Actual rain amounts in our CWA should largely favor 1" or less, with anything higher an exception, so not overly-concerned about flooding (except will need to watch parts of north central KS that had heavy rain last night). IN SUMMARY: Although the official Severe Thunderstorm Watch is currently placed along/south of the state line, there are signs that an isolated/spotty severe threat could extend farther north late tonight into our central and even northern counties. In theory, southern counties should stand the greatest damaging wind threat, while counties farther north would have more of a spotty large hail threat, but as if often the case with these nocturnal summer events, details are not entirely clear cut, and both wind/hail hazards (along with possible Watch expansion) will be monitored closely. No matter how much (or how little) ends up happening overnight, the vast majority of thunderstorm activity within our CWA should be on the decline by roughly 4-5 AM, and the main severe threat over by 3-4 AM. && .SHORT TERM...(This evening through Sunday) Issued at 225 PM CDT Sat Jun 27 2020 A warm front lifted north across the local area this morning. This front shifted the winds to the south and brought a few more clouds to the region than previously anticipated. Thanks to the cloud cover...temps have been slow to climb...but expect the clouds to thin over the next couple of hours allowing temperatures to max out near 90 in most spots as previously thought. While there has been a stray shower just outside the local area associated with this not expect any additional activity locally until later this evening when convection developing to our southwest tracks across the heart of the local area. While instability will peak around 00Z...any diurnally driven thunderstorm activity is expected to remain near the aforementioned surface boundary...and just outside our area to the north/northwest as depicted by the HRRR and RAP. Later in the night...expect an MCS coming out of Colorado to cross northwestern Kansas and move across the local area during the overnight hours. Model placement is still not completely certain...but expect this MCS to roughly cross through the center of the local area. With a modest amount of instability remaining overnight and some enhancement from the LLJ...expect a few strong to marginally severe storms to be possible...with large hail and strong thunderstorm wind gusts being the main threat. For Sunday...expect a period of dry and hot weather to begin across the local area with highs topping out in the mid 90s by afternoon...with a few sporadic heat index values near 100. .LONG TERM...(Sunday night through Saturday) Issued at 225 PM CDT Sat Jun 27 2020 Dry weather is anticipated to start the extended periods as while there will be no shortage of instability across the local area...there also will likely be nothing to trigger it along with a decent CAP in place. As a result...borderline hot weather is expected to continue both Monday and Tuesday with heat index values both days again approaching 100. As we transition into the evening hours Tuesday...models are in fair agreement swinging a negatively tilted trough across the region which could trigger some convection Tuesday evening. With a very unstable airmass in place...if thunderstorms do develop late Tuesday afternoon or evening...expect them to rapidly become severe...and not surprisingly the SPC has parts of our area highlighted in a potential for severe weather...and we will need to continue to monitor this period. Beyond Tuesday...southwesterly junky flow will continue through the end of the week...with small chances for thunderstorms and slightly cooler...yet anticipated. Beyond Friday...however...a large ridge of high pressure is forecast to build across the plains...which could result in a prolonged period of hot and dry weather across the local area if it pans out. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday) Issued at 751 PM CDT Sat Jun 27 2020 General overview/thunderstorm and ceiling expectations: High confidence in VFR ceiling/visibility through at least the vast majority of the period, with by far the main concern being whether (or not) thunderstorms roll through tonight. If they do, they could be briefly severe with a large hail/50+KT wind gust threat, but confidence in thunderstorm coverage is still low enough that feel it is prudent to maintain only a basic "vicinity thunderstorm" group (VCTS) focused 4-10Z for KEAR/5-11Z at KGRI. Obviously later forecasts can introduce a higher-confidence TEMPO group, depending on how things evolve. Outside of the main 6-hour "window of opportunity" for possible convection, fairly high confidence in a dry/storm-free forecast. Ceiling should prevail VFR the vast majority of the time, but there are hints of some "sneaky" MVFR perhaps trying to briefly develop late tonight into Sunday morning, so will "hint" at this with a FEW015 mention. Winds: Outside of any possible briefly-intense wind gusts associated with thunderstorm outflow, winds are not expected to be a major issue, generally prevailing from the south-southeast at sustained speeds at-or-below 12KT and gusts largely under 18KT. Any appreciable low level wind shear (LLWS) overnight should focus slightly south- southeast of the terminals, so will omit any formal inclusion. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...Pfannkuch SHORT TERM...Rossi LONG TERM...Rossi AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Goodland KS
540 PM MDT Sat Jun 27 2020 .SHORT TERM...(This evening through Sunday) Issued at 1231 PM MDT Sat Jun 27 2020 18 UTC Water Vapor Imagery and RAP analysis indicate broad westerly flow aloft over the area,with short wave trough approaching northeastern Colorado per satellite imagery. At the surface, seeing two areas of cumulus developing, one along trough axis from Wray to Limon and another along a convergent area between Burlington and St. Francis. Main forecast concern will center around severe thunderstorm potential late this afternoon tonight. Expect thunderstorms to develop along trough in eastern Colorado by 22 UTC, although secondary area of cumulus to the east of the Colorado state line makes me think there may be 2 areas of initial development, especially as this area is supported by persistent forced ascent due to WAA. Despite the possibility of an isolated cell or two in Kansas, still think forecast will play out similar to yesterday. Storms will form along trough axis, and with high bases and strong DCAPE will quickly form strong cold pool/gust front. With the orientation of 0-3km wind shear, seems like a favorable environment for MCS to develop and remain in balance with cold pool for several hours. With potential organization into a linear mode and strong DCAPE think wind gusts up to 70 mph primary threat, although if isolated storms develop further east ahead of the line hail may become more of a threat. Storms should move across the area fairly quickly with any MCS out of the area by 06 UTC. On Sunday very warm and dry conditions expected. Heating may be enough to overcome any capping and with weak dryline developing would not be out of the question to see an isolated storm. Signal right now looks fairly weak however and think continued dry forecast is in order. .LONG TERM...(Monday through Saturday) Issued at 119 PM MDT Sat Jun 27 2020 The extended starts with troughing over the western US, ridging over the Southeastern and GREAT Lakes regions, and troughing over the New England States. This upper level pattern will produce southwest flow aloft over the Tri-States area and aid in dry and hot (highs are expected to reach at or above 100) conditions through Tuesday afternoon. Add in relative humidity values of 10 to 15 percent will result in possible fire weather conditions. Tuesday afternoon, the models are showing a cold front moving through the region and producing a chance of thunderstorms during the afternoon and evening hours, mainly the the northwestern part of the Tri-State region. For the rest of the week, temperatures will be in the above normal range of the middle 90s and an upper-level ridge will build over the High Plains and influence the area. The However, disturbances traveling within the upper-level flow may result in afternoon thunderstorms each day. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 540 PM MDT Sat Jun 27 2020 Adverse aviation conditions associated with thunderstorms are possible at both terminals late this afternoon and evening, mainly in the 00-06Z time frame. Otherwise, VFR conditions will prevail. South winds at ~15 knots gusting to 25 knots will persist through sunset. Winds are anticipated to become light/variable late this evening. Note -- gusty/erratic winds (possibly gusting to 45-55 knots) will be possible invof any thunderstorms at both terminals this evening (00-06Z). && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...JRM LONG TERM...BW AVIATION...VINCENT
Area Forecast Discussion
National Weather Service Grand Rapids MI
1059 PM EDT Sat Jun 27 2020 LATEST UPDATE... Update .SYNOPSIS... Issued at 238 PM EDT Sat Jun 27 2020 - Mild Weather with little chance for rain in the upcoming week - Seasonably warm temperatures through next week && .UPDATE... Issued at 1059 PM EDT Sat Jun 27 2020 I have added low chance pops over our extreme southwest CWA (Van Buren County) for from now till midnight for thunderstorms. There is an area of increased surface convergence on the cold front slipping south into that area. There is a small are of instability that holds on in that area until the front really get south of there. HRRR model soundings in southern Van Buren County at 11 pm have MU cape near 1000 j/kg. This will be short lived but I would think we should see a few thunderstorms there. && .DISCUSSION...(This evening through next Saturday) Issued at 238 PM EDT Sat Jun 27 2020 - Mild Weather with little chance for rain in the upcoming week - As the upper levels slowly dry, skies will slowly clear today. Patchy fog will remain along Lake Michigan coast through mid afternoon but dissipate as winds mix down. The long wave trough will keep a boundary along Michigan`s southern border this evening. However the propagation of the upper level low into the northeast will keep any precipitation south of the region. There is good consensus that the Upper level low will stall over the Northeast. This will thus stall a high over the Great Lakes. That building high will continue through most of next week. Thus Pops have been lowered with any chance for precipitation on Thursday being stifled by the stable atmosphere. - Seasonably warm temperatures through next week - Along with the high pressure will come warmer than normal temperatures. Expect Maximum Temperature around 10 degrees above normal. with Max Temperatures in the upper 80s to low 90s through the upcoming week. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 700 PM EDT Sat Jun 27 2020 We are expecting skies to become clear by mid evening and winds to become light and variable (at the surface). Sunday will feature light northeast winds with nearly clear skies, however MKG will likely have a lake breeze turn the wind there to the northwest by early afternoon. One possible glitch is near I-94, fog is possible tonight. Some of our high resolution models have dense fog at all of our I-94 TAF sites around sunrise. Given the light winds and heavy rain yesterday this would not be out of the question. For now I have MVFR visibilities around sunrise for those TAF sites. The fog would mix out quickly if it does happen. && .MARINE... Issued at 303 AM EDT Sat Jun 27 2020 High pressure will bring tranquil conditions on Lake Michigan this weekend with waves at or below 2 feet. West winds of 10 to 15 kts are forecast today with offshore winds of around 5-10 kts Sunday that will veer west by around midday. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && $$ UPDATE...WDM SYNOPSIS...Ceru DISCUSSION...Ceru AVIATION...WDM MARINE...Laurens
Area Forecast Discussion
National Weather Service Wilmington NC
1042 PM EDT Sat Jun 27 2020 .SYNOPSIS... Weak high pressure will remain in vicinity of the area thru Sun. A series of weak to moderate upper level disturbances will move across the Southeast States tonight thru early next week, resulting with increasing chances for showers and TSTMs. A cold front will drop into the area early next week, stalling just south of the region by the mid-week period of next week. && .UPDATE... Public: Upped POPs and Cloudiness across the FA, mainly across the southern portions of the FA for the remainder of this evening and overnight to account for the convection and debris cloudiness. The majority and worse of the convection will remain south of the FA within the WNW to NW flow aloft. The outflow and/or any sustainable convection may clip the southern portions of Williamsburg and/or Georgetown Counties thru midnight. Have lowered mins across the FA tonight by a degree or 2 with low 70s covering it. This based on latest sfc dewpoint trends, upper 60s across the FA, then applied to the overnight temp/dewpt regime. Due to the Saharan Dust/Sand plume affecting the Bi-State region tonight thru much of Sun, have included "Hazy" conditions for most zones especially when prevailing VSBY drops to 5 miles or lower. Marine: Tweaked winds overnight into daylight Sun with a solid 15 kt applicable to the ILM NC Waters Only. Will increase the seas to up to 4 ft for the waters from Cape Fear south to Little River Inlet due to short period wind driven waves slightly hier input to the overall seas. Could see VSBY drop to 5NM from Haze, which is due to dust associated with the Saharan Dust/Sand Plume moving across the local waters. && .NEAR TERM /THROUGH SUNDAY NIGHT/... There have been just enough reports of slightly lowered visibility from the Saharan dust that it has been added to the forecast through tonight for SC zones. The HRRR still shows a few showers and perhaps thunderstorms crossing our inland NC counties this evening so slight chance POPs have been left. There is rather unusual model disagreement and thus forecast uncertainty for day 2/Sunday. A disturbance is slated to cross the area in the developing NW flow but models are having trouble resolving the convective signal associated with its passage Sunday eve/night. The GFS for example has rather light precip across the area as the bulk of it passes by to our north while the WRF clobbers us pretty good with what looks like an MCS (currently not the favored solution). SPC has demoted the area from Slight to Marginal but has expressed a similar low confidence while collaborating today. The EC is even slower with the disturbance relegating to midday Monday. Will carry slight chance POPs through afternoon and raised Sunday night to low end of chance range. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... Shortwave exits the coast late Monday morning, setting up some post wave subsidence. Deep northwest flow continues with 5h ridge to the south and cutoff low over New England. A weak front will remain draped across the area along with an abundance of moisture. Subsidence through Mon afternoon will help limit coverage of diurnal convection. However, the lack of subsidence Tue coupled with the boundary and deep moisture results in an increase in diurnal showers and thunderstorms. There will be periodic shortwaves moving in from the northwest which could enhance convection Tue, if the timing works out. Highs will be near climo with lows running above climo. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... Pattern aloft remains unchanged with 5h ridging to the south and southwest and cutoff low over the Northeast shifting off the Mid- Atlantic coast. Deep northwest flow will persist, keeping surface boundary and associated deep moisture in the region. The boundary will act as a focal point for daily showers and thunderstorms. A series of shortwaves will occasionally drop south across the area, potentially enhancing convection if the timing is right. - Afternoon and evening storms possible each day with coverage decreasing slightly late next week. - High temperatures near climo with low temperatures slightly above climo. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Mainly VFR thru the 24 hr period with the exception of the SC terminals where haze (associated with the Saharan Dust/Sand Plume moving across the region) could reduce vsby to 3sm-5sm now thru 15Z Sun. The NC terminals may see an occasional 5sm- 6sm in haze HZ or dust DU, but the bulk of the HZ or DU will pass across SC tonight thru midday Sun. Between 07-11Z, the SC terminals may experience tempo 2sm or lower, especially if winds drop to 3 kt or less with a secondary vsby reduction coming from possible BR. Although temp/dewpoint spreads should remain high enough to prevent BR, the exception will occur at CRE. Daytime CU and the threat of an upper level s/w trof in the late aftn has prompted PROB30 groups for TSRA toward the end of the 24 hr TAF Issuance Period. The sea breeze will again be limited with it`s inland progression due to strong WSW-WNW winds in the lower levels of the atm. Extended Outlook...A disturbance aloft, ie. a s/w trof, could bring scattered showers and storms Sunday evening with brief MVFR/IFR conditions along with isolated wind gusts of 30-40 kt. A mixture of lowered flight categories could occur Mon thru Wed as a series of disturbances aloft move through the area, creating convection possibilities when they pass thru, which may include the overnight hrs. && .MARINE... West to southwest winds are expected now through Sunday night. High pressure will be located over the western Atlantic while piedmont trough stays in place as well-both conducive to SW flow. Waves in the 2-3 ft range will be comprised of a 10 sec SE swell and a 4-5 second wind chop. West-southwest flow Mon will become light and variable Tue and Wed as weak surface boundary settles south across the area. The boundary will stall across the waters, but will not remain in the same location, so winds may vary from southwest to northeast depending on the location of the front. Speeds will generally be under 10 kt from Mon night on. Seas will be a mix of a dominant southerly wind wave and a weak southeast swell. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...DCH UPDATE...DCH NEAR TERM...MBB SHORT TERM...III LONG TERM...III AVIATION...DCH MARINE...DCH/III/MBB
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
957 PM CDT Sat Jun 27 2020 .UPDATE... 957 PM CDT Convection continues to diminish in intensity and coverage across most of the area late this evening, though a cluster of storms had developed earlier over western Lee/Ogle counties along what appears to be a region of low level confluent/convergent flow along the otherwise diffuse synoptic cold frontal boundary. Expectation is that these storms (which are diminishing) will fade away over the next 1-2 hours, ending the localized heavy rain threat there. Farther south, scattered storms continue to fester across central IL, and will likely continue to persist along residual outflow boundaries as a mid-level short wave moves slowly east-southeast downstate. Will maintain chance pops overnight for our southeastern counties, though hopefully this activity will remain more scattered than earlier given substantial flooding over portions of east central IL/northwest IN. Ratzer && .MESOSCALE DISCUSSION... 526 PM CDT Flash flooding is ongoing across a portion of northwest Indiana, in particular southern Newton and Jasper Counties, and likely will be occurring soon in northern Iroquois County. Given the hydrology metrics we are analyzing, namely amounts over 300 percent to flash flood guidance, we have upgraded the impact- based warning (IBW) to considerable given some locations should be seeing significant flooding. On the mesoscale, a northwest to southeast boundary evident the past 2-3 hours on satellite, is draped from Ottawa IL through West Lafayette IN. It appears inflow into this (20 kt of 850 mb flow on ILX VWP) and prorogation vectors to the southeast at a slow speed are heavily offsetting, helping the boundary-initiated storms to train over the same area with little cold pool-driven movement. Individual storm cores have been nearly vertical and have had VIL densities indicative of very heavy rain when considering freezing levels are nearly 15,000 ft. The warm rain process are dominant in these storms as they tap into precipitable waters around 1.8 inches. The growing concern is that these storms continue for another few hours, or possibly longer, in this convergent axis. This convective area is likely being assisted to regenerate by the convectively-enhanced short wave moving eastward near Quincy, IL. This is also helping to enhance moisture convergence in the 700-925 mb layer on the RAP solution. This is forecast to continue at least in that general area through 8 pm. We have again issued a Considerable Flash Flood Warning for this area of northwest Indiana and will continue to highlight in messaging. MTF && .SHORT TERM... 335 PM CDT Through Sunday night... The forecast concerns in this period -- similar to much of the forecast -- are handling the many thunderstorm chances and deciphering if and when the likelihood is higher. The thunderstorm cluster in northwest Indiana as of 3 PM is gradually shifting southeast, and is on the northeastern periphery of the MCV passing eastward through central Illinois. There also is likely a subtle boundary or two (as well as outflow induced from this convection) that will help to trigger more storms in the southern CWA over the next few hours. In this area, the deep layer shear is slightly better (around 30 kt) and has resulted in a few deeper storms capable of gustier downdrafts. The main threat though looks to be a corridor or two of flash flooding due to training storms with very heavy rainfall rates thanks to PWATs above 1.75 inches. Further north, isolated to scattered showers and some storms have started to develop and should continue near/just north of I-80. A couple more may generate on the lake breeze and the weak cool front sinking slowly southward in the far northern CWA. Overall intensity of this convection should not be robust, however individual cores may be. The slow motions and pulsy nature will make for some wind gusts over 35 mph and locally heavy rainfall. Heading into the evening, some convection is likely to fester with a gradual southeast progression. The propensity for lightning should ease after dark and more so overnight, but could continue some showers at least into the overnight over the southeast forecast area. Guidance has a fair amount of cloud cover overnight, but suspect it is overdone. With the high dew point air and spotty areas seeing further boundary layer and ground moistening with rain this P.M., patchy shallow fog is possible lingering into early Sunday morning. The remnant synoptic boundary, which has been modulated some by convective influences, will eventually take shape as a warm front during Sunday and start returning slowly northeastward. Heights in the mid-levels will be building at the same time and overall there will be less of a convective focus or especially impetus compared to the past couple days. However, a continued moist air mass including dew points in the upper 60s to 70 will support potentially enough instability for scattered showers and storms near the confluence of the gradually developing front. Further northeast over the metro the chances appear less, even with a lake breeze, as model soundings are fairly set on a capping influence winning out. As the isentropic ascent strengthens on Sunday evening into the night, the potential for convection will increase. Also there are indications of a weak short wave or MCV moving southeastward near or into the northern Illinois CWA Sunday evening. Confidence on that is low, but do have chances increasing through the night. The shear/instability space especially during Sunday night is enough for some potent cores to strong to severe limits, and possibly organized convection into northern Illinois north of I-80 from the northwest if that MCV were to come to fruition. MTF && .LONG TERM... 257 PM CDT Monday through Saturday... Hot and humid will be the story through the work week with the area situated under an upper level ridge with highs mostly in the low 90s and dewpoints in the 70s expected. Easterly flow should keep things a bit cooler near the lake. The extended is littered with multiple weak waves embedded beneath the ridge resulting in multiple precip chances through the extended thanks to the lingering moist and unstable airmass in place. The better chances look to be Monday through Wednesday with chances decreasing toward the end of the week. Winds will turn northeasterly toward the end of the period which should help temps and dewpoints ease slightly as we approach the Fourth of July holiday weekend. Petr && .AVIATION... For the 00Z TAFs... Aviation forecast concerns: * Isolated TSRA possible early this evening mainly near southern Chicago metro terminals (MDW/GYY). Not expecting widespread coverage, and should dissipate with sunset. * Messy wind forecast across Chicago terminals, with lake breeze trying to move inland, and several convective outflow boundaries converging from the south/southwest early this evening. Wind direction will likely be somewhat variable across the Chicago TAF sites this evening. * Low probability of some fog/low stratus development late Diffuse cold frontal boundary was near the IL-WI border late this afternoon, while a residual outflow boundary from previous convection has become a focus for renewed thunderstorm development this afternoon south of the I-80 corridor. A couple of smaller outflow boundaries have spread north into the central/southern parts of the Chicago metro area from this activity, with a few isolated SHRA/TSRA primarily across the southern metro. Convective SHRA/TSRA have generally struggled over the metro, and are not expected to become widespread and should dissipate with sunset. In addition, the lake breeze boundary had struggled to move inland during the afternoon, remaining east of the terminals, though has recently shown some west- southwestward push especially north of ORD. Expectation is that the lake breeze will make it into ORD this evening, with a wind shift to the northeast for a time. However, presence of multiple convective outflow boundaries across the metro makes the wind direction forecast rather complicated in the near term. Winds should become light and probably somewhat variable after sunset, before eventually turning light east- southeast by Sunday morning with a bit of lake breeze enhancement by early afternoon. One other potential concern is with guidance depicting the possibility of some fog/low stratus development mainly across northern Chicago metro areas late tonight. Already some marine haze noted in webcams along Kenosha-Racine WI shore late this afternoon, and models indicate this may spread/develop inland late tonight. Guidance seems to be somewhat overdone with the extent currently based on Satellite imagery, though did indicate a tempo for ORD of an MVFR vis/low IFR cloud layer pre-dawn. Confidence is fairly low with this occurring and affecting ORD or other terminals, but worth monitoring for early Sunday morning. Ratzer && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
603 PM CDT Sat Jun 27 2020 .SHORT TERM... (Through Late Sunday Afternoon) Issued at 312 PM CDT Sat Jun 27 2020 Challenging convection forecast for this afternoon and tonight. An MCV left over from last night`s convection over Kansas and Nebraska is moving east across Missouri this afternoon. This MCV combined with what`s left of a cold front is expected to produce another round of thunderstorms later this afternoon and tonight...the beginnings of which may be developing in central Missouri at this time. Current thinking is that the showers currently forming will continue to expand in coverage and strengthen through the afternoon. The HREF ensemble paintball plot shows that the majority of the members blow up convection along and about 40 miles north and south of I-70 by late this afternoon. The area of convection pushes south, likely due to outflow, and then starts drifting north again as the warm front gets pushed northward by the low level jet. If the RAP is right, there will be just enough instability available for these storms to produce marginally severe hail and wind, although any severe storms should be fairly isolated and will probably weaken after sunset. Forecast precipitable water approaching 2 inches and potential for back- building/training storms is concerning for heavy rain and flooding. Have decided not to issue any hydro watches at this time as antecedent conditions are rather dry. Sunday should be quieter than today with warming temperatures. There may be some lingering showers/storms along the warm front as it continues moving through Illinois...primarily during the morning. Carney .LONG TERM... (Sunday Night through Next Saturday) Issued at 312 PM CDT Sat Jun 27 2020 Little has changed in the forecast for next week. Upper level pattern becomes highly amplified with large cut off lows over the eastern and western CONUS, and ridge extending from the deep south north through the Mississippi Valley. This blocky pattern holds into next weekend. Both the GFS and ECMWF ensembles show fairly low standard deviation in the upper pattern, so confidence is high in this forecast. This translates to a period of warm and humid weather for the Mid Mississippi Valley with highs in the upper 80s to low and mid 90s. Medium range guidance has been consistently pushing a short wave into the upper ridge on Monday where it cuts off and gets stranded over the Mid Mississippi Valley Monday night into Tuesday. According to all of the guidance, this compact low will be enough forcing to allow convection to develop each day through the week despite the larger scale upper ridge. Have therefore kept PoPs in the forecast through next Saturday. Carney && .AVIATION... (For the 00z TAFs through 00z Sunday Evening) Issued at 553 PM CDT Sat Jun 27 2020 Storms will persist along and just south of the I-70 corridor for the next few hours before storm chances shift into southern MO and IL into the early morning hours. To the north and east of these storms, guidance is showing at least a chance for cigs to drop below 3kft, with the best chances toward UIN. Therefore have a few hours of MVFR cigs at UIN and limited the St. Louis terminals to SCT015 through tomorrow morning. Around daybreak, storm chances will then shift back to the north, moving out of the area by mid day. This will likely bring isolated to scattered storms to the area, but confidence on these storms impacting any of the terminals is low. For now have kept the TAFs limited to VCTS during this period, though should a storm hit a terminal, expect to see cigs and visbys ball below VFR criteria. BSH && .PRELIMINARY POINT TEMPS/POPS... Saint Louis 73 95 78 95 / 70 40 10 40 Quincy 70 90 73 90 / 30 40 20 50 Columbia 71 91 73 90 / 50 20 10 40 Jefferson City 72 92 74 92 / 60 20 10 40 Salem 72 90 73 93 / 60 50 20 40 Farmington 73 91 73 91 / 60 20 10 30 && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
1005 PM CDT Sat Jun 27 2020 .NEAR TERM /Now Through Sunday night/...A look at the geo-potential height field aloft shows a short wave trof at H30 advancing eastward across the northern border of AL/MS while in the lower levels, high pressure over the FL Peninsula extends west into the central Gulf coast. Even with the passing high level impulse, convection has been spotty despite an environment that was loaded with instability where MLCapes ranged from 2000 to 4000 J/KG. The only item lacking was a point of surface focus. Otherwise, forecasters expect the outcome would`ve been starkly different. Going into the evening, the radar is quiet, but will maintain a small PoP north of US Highway 84 where there is still potential for an evening pop-up storm. The remainder of the night looks rain-free. Low to mid-layer high pressure ridge over the Gulf noses northward over the deep south Sunday. At H30 though, a trof axis aligned over the southeast may be enough to support a chance of showers and storms during time of max heating and atmospheric destabilization when MUCape values swell to 2000 to 4000 J/KG. Deep layer moisture changes little with afternoon PWAT values ranging 1.8 to 2 inches which remains well above climatology for the end of June. Storms Sunday afternoon could be strong at times; however, the shortwave is not as potent and weak bulk-shear magnitudes favors a low risk for any severe weather. Temperatures will continue to be hot with highs in the upper 80s along the coast to lower 90s inland. Some locations east of I-65 could see the mid 90s on Sunday as the influence of the upper level shortwave ridge keeps cloud cover down and allows for max solar heating before storms develop. Heat indices in these areas possibly 100 to 105. Lows remain in the 70s. Perhaps upper reaches of the 70s/near 80 over beach areas. /10 && .PREV DISCUSSION... /issued 559 PM CDT Sat Jun 27 2020/ AVIATION... 00Z issuance...The potential exists for isolated shra/tsra along and north of US highway 84 this evening which could bring brief lower cigs and strong gusty winds. Otherwise, mainly high based clouds streaming eastward over the Gulf coast with VFR conditions expected tonight. Light and variable to calm wind after sunset. /10 PREV DISCUSSION... /issued 427 PM CDT Sat Jun 27 2020/ NEAR TERM UPDATE /Now Through Sunday/...Storms have struggled this afternoon with dry air entrainment keeping storm development quiet so far. Conditions are still favorable and what few showers we have seen should help moisten up the environment to where isolated to possibly scattered storms should still develop over the northern half of the forecast area. Visible satellite shows clearing over most of Mississippi with agitated cumulus across most of the state. A weak boundary (likely seabreeze) was noted surging northward across the area as another boundary from earlier convection to our north drops south. What storms do develop will likely be focused along these two boundaries and who sees rain might be highly dependent on the location of mesoscale boundaries this afternoon. If (starting to look like a bigger if) we can get storms this evening, a severe thunderstorm could still be possible with damaging winds. PREV DISCUSSION... /issued 1256 PM CDT Sat Jun 27 2020/ Relatively zonal flow persists across the area as we are sandwiched between a building upper ridge over the Florida Peninsula and very subtle and weak troughing over northern Pennsylvania and southern New York. Embedded in this flow is a subtle but noticeable shortwave currently over south central Louisiana. This shortwave will progress across the southern half of our area as we head through the afternoon and evening. Increasing ascent ahead of the shortwave coupled with increasing low-level convergence proceeding the surging afternoon seabreeze and a fairly deep moist profile with PWATS approaching 1.8 to 1.9 inches will be sufficient for storm development during the afternoon. The best coverage will likely be north and west of I-65 where synoptic ascent will be maximized. Morning high res models have depicted this; however, coverage on the models seems to be on the lower side. This has been a common trend the last few days and has always verified with more storms than modeled. With that in mind, I kept pops near 50 percent over the far northwestern locations decreasing to around 10% along the coast. Storms this afternoon will have to watched carefully as SPC RAP mesoanalysis shows between 2500 to 3000 J/KG of MLCape already present. As the shortwave moves through, bulk shear values will approach 35 knots which is supportive of at least some cold pool maintenance and storm organization (likely multicellular clusters/bowing segments). Looking at the 12z Jackson MS sounding, steep 700-500 mb lapse rates approaching 9 degrees per KM with drier air over top a very moist boundary layer would support the production of wet microbursts capable of damaging winds. Some small hail up to nickle and possibly quarter sized could occur in the stronger storms given the lapse rates. The best chance for a severe storm will likely be further northwest where the drier air aloft is a little more prevalent. Nonetheless, conditions are supportive across most of the area for gusty winds and the SPC has highlighted most of the area in a marginal risk for severe weather. Storms should subside late evening as the shortwave progresses east and we enter the unfavorable left entrance region of the jet streak. Shortwave ridging will build over the area tonight before another shortwave trough moves through the upper pattern tomorrow afternoon. Once again another round of showers and storms will be possible across the area. Some storms could also be strong; however, the shortwave is not as potent and the lack of any shear and drier air aloft will limit severe potential. Temperatures will continue to be hot with highs in the upper 80s along the coast to low 90s inland. Some locations east of I-65 could see the mid 90s on Sunday as the influences of the upper level shortwave ridge keeps cloud cover down and allows for max solar heating before storms develop. Lows will remain in the mid 70s given the high dewpoints. A low risk of rip currents will continue through the period. BB/03 SHORT TERM /Sunday night Through Tuesday night/...An upper high pressure area over the Gulf of Mexico will expand westward to include northern Mexico through the short term. An upper ridge extending northward from the north central gulf to the western Great Lakes region will remain intact and shift slightly eastward through noon Monday. The upper ridge will then breakdown into a zonal flow over the southeast conus as a series of upper level impulses and shortwaves exiting the central Great Plains passes north of the area. Meanwhile, the local area remains on the western periphery of a surface high in the western Atlantic, which will maintain our general southerly to southwesterly flow. The isolated to scattered convection late Sunday afternoon will dissipate by sunset with the loss of daytime heating. Due to influence of the upper ridge aloft, expect dry conditions Sunday night through much of Monday morning, followed by scattered afternoon showers and thunderstorms due to decreasing stability. Again the convection late Monday afternoon will dissipate by sunset with dry conditions overnight. Scattered afternoon showers and thunderstorms are expected again Tuesday afternoon. A few of the stronger thunderstorms both days could have brief gusty strong winds. Daytime highs Monday and Tuesday will range from 88 to 93 degrees, and remain muggy. Expect widespread 100-105 heat index on Monday and around 100 on Tuesday. Low temperatures will be a carbon copy each night with temperatures only falling into the low 70s inland with upper 70s at the beaches. Rip current risk remains LOW through the short term. /22 EXTENDED TERM /Wednesday Through Saturday/...A large upper level ridge will build over the central conus through the remainder of the week, while an upper low over the northeastern conus deepens. An upper shortwave west of the low pressure will progress southward over the Ohio River Valley on Wednesday. This upper shortwave will continue to dive southward over the southeast conus and stall through the remainder of the extended period, with a possible cutoff low forming over the region on Friday. Meanwhile, the local area remains on the western periphery of a surface high as it migrates southward, but will still maintain a general southwesterly to westerly flow through Friday. A cold front approaching the region late in the week may stall across the forecast area on Friday, and possible move as far south as the northern gulf coast late Friday night into Saturday morning. With a slight increase in overall moisture, the upper trough, and a frontal boundary passing through, there will be the potential for daytime scattered to likely showers and thunderstorms mid week, and numerous to categorical showers and thunderstorms Thursday through Saturday. Isolated to scattered convection is expected during the overnight hours. /22 MARINE...A light southerly flow continues through Tuesday with occasionally moderate onshore flow over the nearshore waters and bays during the afternoon. Isolated showers and thunderstorms will be possible each afternoon along the seabreeze and nearshore waters and bays. Winds will become more westerly by Wednesday and Thursday. BB/03 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...None. FL...None. MS...None. GM...None. && $$ This product is also available on the web at:
Area Forecast Discussion
National Weather Service Marquette MI
750 PM EDT Sat Jun 27 2020 .SHORT TERM...(This evening through Sunday) Issued at 326 PM EDT SAT JUN 27 2020 Water vapor imagery and RAP analysis show mid to upper level ridge beginning to amplify over the central CONUS in response to a trough now digging into the Pacific NW Coast. The central CONUS ridge will continue to amplify through the rest of the weekend into early next week over the Western Great Lakes as the trough over the western CONUS continues to amplify and a blocking closed low sets up over New England. This amplifying ridge will lead to dry conditions and a warming trend over the area. As for today, conditions have been drier with some gustier nw winds of 15-20 knots in the wake of last night`s cold frontal passage. Some lingering moisture and cyclonic flow near a shortwave trough moving through eastern Ontario has led to some stratocumulus clouds and patchy fog over eastern Lake Superior and eastern Upper Mi this morning into early afternoon, but expect these clouds and fog to dissipate with increased ridging from the west later this afternoon. Onshore nw flow along with a developing lake breeze have kept conditions cooler immediately downwind of Lake Superior this afternoon with highs generally in the lower to mid 70s, and it might not get out of the 60s for locations stuck longer in lower cloud cover along the eastern Lake Superior shoreline. Farther inland, well away from Lake Superior`s influence, temp readings near the WI have made it into the lower 80s. Tonight, a surface ridge moves across the Upper Peninsula tonight as upper-level ridging starts to build into the region. This will favor a pleasant night with light winds and clear skies. After midnight, return flow starts to work into western parts of Upper Michigan where overnight lows will remain milder, in the mid to upper 50s. Across the east, where the center of surface ridging will track, overnight lows will be locally cooler, perhaps dipping into the upper 40s at some locations. There could be some patchy fog that develops overnight, but given the drier air working into the region confidence wasn`t high enough to include mention within the forecast at this time. Sunday, mid-level ridge will continue to amplify over the western Great Lakes to Hudson Bay, supporting sfc high pres ridging from Hudson Bay to MI. Meso highs will develop during the day over far eastern Lake Superior and northern Lake MI, resulting in onshore winds off Lake MI and onshore winds with an easterly component along Lake Superior. Lake breeze may fail to push much onshore over far western Upper MI. Under mostly sunny skies, expect highs in the 80s in the interior, warmest w. .LONG TERM...(Sunday night through Saturday) Issued at 342 PM EDT SAT JUN 27 2020 Upper level ridge axis moving into the Mississippi River Valley Sunday will set off an omega-like blocking pattern that will extend through much of the extended period. As this ridge settles in and continues to build into northern Canada, anomalous troughing will amply in the western CONUS through the middle of next week while an mid-upper level low remains nearly stationary over the northeast. This will position the Upper Great Lakes on the cyclonic side of the ridging, which will expose the region to a few northward propagating short waves moving through the trough into Canada. Through the week the western CONUS trough will deamplify which will result in the some uncertainty in the ridge. Overall, this will result in a few opportunities for precip early in the week in the west and be accompanied by warm to hot temperatures and high humidity. Confidence is high that daytime surface high over the region will erode as a shortwave lifts into the region Sunday night into Monday. 12z guidance has become more consistent, reaching more of a consensus then previous runs on the evolution of this feature. By Monday morning, the shortwave looks to lift into mainly the western portion of the forecast area. This would bring a chance of precip mainly to the west and central. Daytime instability looks to increase so its possible there could be some thunderstorms, but severe weather is not anticipated given the weakly shear`d environment. As ridging over Ontario stretches west during the day, this looks to elongate and slow/stall the feature over the Arrowhead to just north into Canada through early Wednesday. Elected to keep chance PoPs over mainly the western lake and western UP through Wednesday morning. PWATS within this airmass will be anomalously high, and moderate to heavy rain cannot be ruled out in any showers. With 850mb temps climbing near 16-19C Monday and Tuesday, surface temps in the mid 80s is looking likely away from the lakeshores and near 80 by the lakeshores. Some isolated pockets near 90 cannot be ruled out in areas prone to SE downsloping, especially if widespread precip doesn`t take place. With the weak synoptic flow, afternoon lakebreezes could help to cool things off some in the late afternoon. Guidance suggested the dewpoints climbing into the 60s is likely as well, and some suggested near 70 in the west. Overnight lows in the 60s are expected, but with little relief in humidity, expect the uncomfortable days to transition into uncomfortable nights. Beyond this, model guidance begins to diverge on how the mid- upper level ridging will unfold. The 12z guidance suggests the upper level ridge continuing to block any incoming shortwaves from the south and even the north on the east side of the ridge. Given how much the model guidance has changed between the previous 0z, 6z and now 12z runs, confidence is low on how effective the ridge will be at keeping the region dry. Consistent signals between model runs for the heat and some humidity to stick around during the remaining week are there so continued the heat going into the 4th of July. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 749 PM EDT SAT JUN 27 2020 VFR conditions are expected through the forecast period with winds under 10 knots. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 326 PM EDT SAT JUN 27 2020 Surface high pressure stationed over the area will keep winds below 20 knots this weekend into next week. Expect patchy fog over eastern Lake Superior this afternoon into tonight. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...JP AVIATION...JLB MARINE...Voss
Area Forecast Discussion
National Weather Service Paducah KY
856 PM CDT Sat Jun 27 2020 .UPDATE... Issued at 846 PM CDT Sat Jun 27 2020 We have allowed the Lake Wind Advisory to expire, and issued a Flash Flood Watch for the Evansville Tri State area through 18Z Sunday. The first round of heavy rainfall that is currently exiting the area produced 1 to 2 inches of rainfall over much of the Flash Flood Watch area. This has basically primed the pump for the next 18 hours or so. The next round of convection is approaching from eastern Missouri. Recent runs of the HRRR indicate that multiple rounds of convection will traverse the northeast portions of the forecast area through the night into Sunday morning, as persistent 30kt 850mb southwesterly flow provides a constant inflow of moisture to the area. WPC QPF now has 1.5" to nearly 3" through 18Z Sunday. It had been pretty dry recently, so much of the region will likely be able to handle a couple of inches of rainfall, but some less fortunate areas, could see some flash flooding. The threat will increase with each round of convection. Extensions of the Watch may be needed. && .SHORT TERM...(Tonight through Sunday night) Issued at 320 PM CDT Sat Jun 27 2020 The biggest concern in the short term seems to lie with the heavy rain potential from repeating/back-building storms along/east of the MS River tonight into early Sunday, as a trof of low pressure aloft works its way from the MS River Valley east into the lower OH Valley. Low level (H925 to H85) moisture transport is expected to increase tonight ahead of the the trof as swly winds pick up. Could also see PWs up close to the 99th percentile of normal for late June. However, given degree of placement/timing uncertainties and the fact that much of that region has been placed in D0 drought, decided to hold off on a flash flood watch at this time. Should see a return to some sunshine from west to east slowly during the day Sunday, once the trof axis shifts farther east. However, should end up pretty darn uncomfortable Sunday afternoon, esp over se MO/far western KY and southwest IL, with sticky dew points in the lower half of the 70s and heat index values creeping up close to the century mark. .LONG TERM...(Monday through Saturday) Issued at 320 PM CDT Sat Jun 27 2020 The start of the extended forecast will see a blocking ridge in the middle of the country, flanked on both sides by closed lows. The models have shifted the ridge slightly east this run, putting the Quad State near the center of the ridge axis. The low to the northeast will have a trailing cold front across northern Ohio to Illinois. Precipitation Monday remains more likely in the northern and eastern portions of the forecast area, closer to the front. However, with the models centering the low slightly further east, PoPs Monday are lower than in previous runs. This front will slowly drift southward over the following days. The GFS, Canadian, and ECMWF all place an upper-level low in Missouri on Tuesday. Tuesday through Wednesday is when the models are most agreeable on putting the Quad State to the east of this system. With instability provided by the low and moisture from the Gulf, this would be the most likely period in the extended to have thunderstorm activity. For the remainder of the workweek, there is ample opportunity for precipitation to occur with the stalled out front or the upper-level low meandering around the middle Mississippi Valley providing a focus for developing convection. Declining model agreement at this range is what leads to a decrease in PoPs and thunder chances. By the end of the week the eastern closed low will head out into the Atlantic. The closed low to the west will have moved towards Canada along the ridge. The ridge itself will decrease in amplitude but broaden in both directions to cover most of the contiguous United States. This will leave the upper-level low as the primary remaining region for development of storms. Highs at the start of the long term will be driven by Gulf flow, reaching the upper 80s to lower 90s Monday and Tuesday. Afterwards, influence from the cold front to the north slowly dropping southward through the area will result in slightly cooler highs for the remainder of the workweek. Gulf moisture will keep dew points near 70 and lows in the lower 70s.&& .AVIATION... Issued at 632 PM CDT Sat Jun 27 2020 Tracking thunderstorm complexes across the taf sites is the main forecast issue. One round of storms over the kevv/kowb areas at 23z will pass quickly east of the area. Another round of storms over east central Missouri at 23z will move east across southern IL/southwest IN/northwest KY late this evening into the overnight hours. Current indications are that kcgi/kpah will be on the southern fringe of this activity. Once the activity sets in, widespread mvfr cigs are likely to become entrenched at least through midday Sunday. However, kpah and kcgi are currently expected to remain vfr as the bulk of these storms should stay north of those sites. Winds will remain southwest, becoming gusty during the daytime hours. && .AVIATION... Issued at 632 PM CDT Sat Jun 27 2020 Tracking thunderstorm complexes across the taf sites is the main forecast issue. One round of storms over the kevv/kowb areas at 23z will pass quickly east of the area. Another round of storms over east central Missouri at 23z will move east across southern IL/southwest IN/northwest KY late this evening into the overnight hours. Current indications are that kcgi/kpah will be on the southern fringe of this activity. Once the activity sets in, widespread mvfr cigs are likely to become entrenched at least through midday Sunday. However, kpah and kcgi are currently expected to remain vfr as the bulk of these storms should stay north of those sites. Winds will remain southwest, becoming gusty during the daytime hours. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...Flash Flood Watch through Sunday afternoon for ILZ075>078-082- 083-087. MO...None. IN...Flash Flood Watch through Sunday afternoon for INZ081-082- 085>088. KY...Flash Flood Watch through Sunday afternoon for KYZ014-015- 018>020. && $$ UPDATE...DRS SHORT TERM...GM LONG TERM...ATL AVIATION...MY
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Sunday) Issued at 349 PM CDT Sat Jun 27 2020 Cloud cover has been slow to clear out in far eastern KS, having only scattered out in the last hour or so as of 20Z. The rest of the area has seen clearing skies with mesoscale subsidence behind this morning`s storm complex. 20Z water vapor imagery shows the remaining MCV well off to our east with a shortwave in CO ahead of a broad trough over the Pacific Northwest. As a result of the clouds, have trimmed highs for a small eastern part of the forecast area to the low to mid 80s, while everyone else should still reach the upper 80s to low 90s with more insolation occurring this afternoon. Regarding thunderstorms late this afternoon/early this evening, have backed down on PoPs with only low-end chances remaining through tonight. The HRRR has been showing a decreasing trend throughout the day likely due to less destabilization, with only a few isolated storms popping up in east central KS after 02Z. Since CIN increases by this time, thinking this might be a result of speed convergence with a strengthening LLJ later this evening. In any case, any storms that develop are expected to be isolated and short-lived. North central KS could see storms overnight associated with the shortwave currently in CO; however, these are expected to weaken as they move northeast through the state. Southwesterly flow is expected to keep plenty of moisture in the area on Sunday with hot temperatures in the 90s area-wide. Heat indices are forecast to reach the 98 to 105 degree range. Have held off on issuing a Heat Advisory for now, but one may be warranted if these trends continue and confidence in reaching criteria increases. .LONG TERM...(Sunday night through Saturday) Issued at 349 PM CDT Sat Jun 27 2020 The broad trough previously mentioned will slowly progress into the western US and then weaken later this week, with embedded waves bringing small precipitation chances on and off throughout the week. The main story will be the persistent heat as high temperatures reach the 90s each day this week and morning lows only fall back to the 70s. These hot temperatures with dew points in the 70s will combine to bring heat index values in the upper 90s to low 100s, so we will need to monitor the potential for heat headlines. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 621 PM CDT Sat Jun 27 2020 A few isolated storms will be possible south of the terminals this evening, but are expected to dissipate in the next 1-2 hours and should not impact any of the TAF sites. Winds at 2-3 kft will increase out of the southwest early Sunday morning, resulting a period of LLWS or low-level turbulence at all sites, especially KTOP and KFOE. Although there is a small possibility of some storms developing around the area during the early morning hours, uncertainty is too high to warrant a mention with this issuance. Ceilings are expected to remain VFR, and winds will increase out of the south by late morning, becoming gusty by 18z. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Picha LONG TERM...Picha AVIATION...Laflin
mentioned in the previous long term forecast discussion,
deterministic models are beginning to show increased moisture across
Arizona, perhaps enough to generate some showers and thunderstorms for Mohave County as early as Thursday and lingering with a similar pattern through the weekend. At the moment, a slight uptick in PoPs were noted in the morning run of the NBM for these periods, but not enough to produce QPF or mentionable Wx, keeping this well east of the CWA. However, ensemble meteograms of both the EC and GEFS show about 10% of members indicating precip as far west as Kingman beginning Friday. Would not be surprised to see PoPs increase in later forecasts as a result. && .FIRE WEATHER...Not much change to the fire weather forecast through the weekend. Elevated fire conditions today as increasing winds out of the south and southwest today reach up to 30 mph but staying below critical. The main focus is Sunday where a well forecast wind event will take place, ramping up by late morning and persisting through the evening hours. While critical thresholds look to be exceeded across the Great Basin, highest wind gusts will be higher elevations of the eastern Sierra and Spring Mountains. Gusts over 60 mph out of the west/southwest respectively are not out of the question, especially for the Sierra slopes south of Aspendell to Olancha. Peak gusts are expected between 3PM and 9PM in those areas. Winds should decrease through the overnight hours Sunday night into Monday morning with the main system shifting east. Wind gust potential is significantly lower Monday but still near critical for northwest Arizona (zone 102). && .AVIATION...For McCarran...Winds will favor the easterly direction early this afternoon; becoming more southerly between 22z-00z. Speeds during this time should remain around 10 knots or less with intermittent gusts to around 15 knots possible. Overnight, south to southwest winds will remain up around 9-13 knots with continued gustiness. Winds will begin to rise around 15z on Sunday and peak between 21z-01z Sunday afternoon at speeds of 20-30 knots gusting up to 40 knots. For the rest of southern Nevada, northwest Arizona and southeast California...Breezy, south to southwesterly winds are expected for much of the area this afternoon and into tonight. An isolated shower or storm will be possible overnight across northern Lincoln County but otherwise dry for the period. Southwest winds will begin to pick up between 15z-18z on Sunday morning; peaking between 21z-03z. Widespread wind speeds of 20-30 knots gusting 30-40 knots are expected through tomorrow evening. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE...Pierce DISCUSSION...TB3 AVIATION...Guillet For more forecast information...see us on our webpage: or follow us on Facebook and Twitter