Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/28/21

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
902 PM CDT Tue Jul 27 2021 .UPDATE... Issued at 901 PM CDT Tue Jul 27 2021 Temperatures have fallen in the last hour, so allowed the heat advisory to expire. UPDATE Issued at 630 PM CDT Tue Jul 27 2021 Given the current temperatures and heat indices which show multiple sites remaining above 100 degrees, decided to extend the heat advisory until closer to sunset when temperatures will fall more quickly. Otherwise, the forecast remains on track this evening with no further changes needed. && .SHORT TERM...(This Evening through Wednesday Night) Issued at 231 PM CDT Tue Jul 27 2021 Upper high centered over the Western High Plains will continue to build over the forecast area through Wednesday. Meanwhile, a sfc front stretching across northern South Dakota is expected to gradually push back north tonight as the LLJ returns to the region. The LLJ impinging upon this frontal boundary may be enough to get convection to develop later this evening and overnight across NE SD, and WC MN. The activity would then move southeast across parts of eastern SD and western MN. Any convection that forms would be on the southern edge of the westerlies (good shear), and would have plenty of moisture/instability to work with, so a severe storm or two isn`t out of the realm of possibilities. Again tonight, wind and hail are the main threats given the abundance of CAPE. At the same time you have a pretty healthy EML developing across the region, with H7 temps climbing to 15C or greater across the western CWA tonight and Wednesday. This should effectively cap off most convection chances west of the James valley. A sfc front will move southeast across the CWA on Wednesday, and as the winds turn more southwest/west, temperatures are likely to go up even further vs today. Hundred degree readings may well be common in the afternoon. As for any chance of rain, it appears that it`ll be capped with little if any chance for measurable pcpn as front migrates to the south. Behind that front, a much drier airmass will advect into the area for Thursday, along with cooler temperatures. Will also maintain elevated smoke mention through Wednesday given the output from the HRRR smoke model. Last item, heat indices. Again on Wednesday the heat index should reach into the 100s and thus will maintain the advisory for Wednesday afternoon across the forecast area. .LONG TERM...(Thursday through Tuesday) Issued at 231 PM CDT Tue Jul 27 2021 The period opens Thursday with the upper ridge west/upper trough east pattern intact over the CONUS. That leaves the CWA under northwest flow aloft. With only minor variations expected in amplitude and position of this upper level pattern, northwest flow early on in the period eventually becomes north-northwest flow late in the period. Deterministic and ensemble-based model solutions all generally support a cooler/closer-to-normal low level thermal/mixing pattern from Thursday through Tuesday. Typical of northwest flow pattern sequences, most of the period is dry and when models do generate qpf over the CWA it is more isolated in nature vs. widespread, and they generally lack agreement on timing/placement of areas of qpf. From the probabilistic perspective, other than the far southwestern zones from late Thursday night through Friday evening, the chances of seeing just 0.01 to 0.10 inch of qpf over the CWA are fairly low. Not saying there couldn`t be a handful of forecast periods with a couple of storms to deal with. However, trying to resolve that kind of detail this far out in time within this kind of weather pattern holds very little skill/confidence. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening) Issued at 630 PM CDT Tue Jul 27 2021 Terminals KABR,KATY,KPIR,KMBG VFR conditions are expected through the next 24 hours. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...Heat Advisory from noon CDT /11 AM MDT/ to 7 PM CDT /6 PM MDT/ Wednesday for SDZ003>011-015>023-033>037-045-048-051. MN...Heat Advisory from noon to 7 PM CDT Wednesday for MNZ039-046. && $$ UPDATE...Wise SHORT TERM...TDK LONG TERM...Dorn AVIATION...Wise
National Weather Service Wakefield VA
1059 PM EDT Tue Jul 27 2021 .SYNOPSIS... A frontal boundary will wash out across the region today as weak high pressure builds in from the north. A stronger cold front crosses the region Friday with high pressure building in from the north on Saturday. && .NEAR TERM /THROUGH WEDNESDAY/... As of 1055 PM EDT Tuesday... Latest sfc analysis reveals a rather diffuse sfc boundary in place across area this evening. Localized/isolated convection earlier this evening produced some locally heavy rainfall in Richmond and just south into northern Chesterfield county, with additional locally heavy showers and embedded TSRA over eastern Chesapeake/inland Va Beach and the MD eastern shore south of KSBY. Rainfall amounts of 2-3 inches with locally heavier amounts occurred across Chesapeake/VB, with lesser amounts of up to 1.5 over RIC metro and the lower MD eastern shore. Convective coverage has, as expected, quickly waned with loss of heating, owing to minimal effective shear. Expect mainly quiet wx for the balance of the evening and the overnight, though we have maintained a slight chc PoP over NC counties, as ongoing iso convection across the foothills/ (VA/NC piedmont) potentially making it across to our western tier of counties and NE NC coastal plain zones now through 06Z (new 00z NAM and past few runs of HRRR have shown this potentially occurring). Otherwise, seasonably warm/humid overnight under a partly cloudy sky...with some patchy fog late tonight. Early morning lows in the upper 60s/low 70s most areas (locally mid 70s along the coast in SE VA/NE NC. On Wed, the flow aloft shifts more to the NW (compared to WNW) as the next shortwave pivots around the base of the deep upper trough across eastern Canada. This may bring a slightly better chance for aftn/early evening tstms. The low level flow remains fairly weak so once again expect some sea-breeze influence to get the storms going in the aftn. Will still only have PoPs 20-30% across the area, but the storms may be a little stronger and longer lived than on Tue. Partly sunny on avg with highs low- mid 90s inland except upr 80s/around 90F at the immediate coast. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... As of 335 AM EDT Tuesday... Partly cloudy other than a few early evening showers/tstms with lows Wed night upper 60s- lwr 70s. For Thu, partly to mostly sunny ahead of an approaching cold front. Models show sct convection developing late aftn/eve across the nrn third of the fa but will spread at least 20% PoPs into southern VA late. The front pushes S Thu night with the potential for some redevelopment of showers/tstms mainly over the S on Fri. Highs in the 90-95F range for Thu (upper 80s NE), with lows in the upper 60s to lower 70s. Highs Fri mainly in the upper 80s to lower 90s. Then cooler Fri night with lows mostly into the 60s except lower 70s far SE. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... As of 355 PM EDT Tuesday... Flow aloft shifts more to the W this weekend with the upper level ridge centered from the western Gulf of Mexico to the northern Rockies and the upper trough sharpening over eastern Canada and pivoting S into the NE CONUS. This should push the cold front S of the area Fri night with weak high pressure settling in from the N for Sat. Mainly dry/cooler conditions Sat with highs in the mid 80s. The models then show another push of a rather strong shortwave across the eastern Great Lakes into New England later Sun into Mon. This would potentially drive another cold front through the area Sun into Mon. Will have low chc PoPs during this period then mainly dry for Mon with highs in the 80s. By later Mon into Tue, the models are in decent agreement that the upper ridge amplifies into western Canada with a trough diving S nearly to the Gulf of Mexico. The flow aloft shifts to the SW and increasing moisture is expected Mon night into Tue as a sfc trough develops across the SE CONUS. Will have PoPs above climo for Tue with highs only in the lower 80s. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... As of 755 PM EDT Tuesday... Isolated showers and t-storms have quickly diminished in areal coverage to begin the 00z TAF period. Mainly VFR conditions are expected for much of tonight, though some late night mist possible in the piedmont, mainly W-SW of KRIC and around KSBY after 06z. Mainly VFR again for Wed morning, before additional showers and storms Wed aftn and evening. SCT-BKN CU deck 5-8 kft AGL expected after 16z, with potentially a bit higher coverage of aftn/evening tstms compared to earlier today. Outlook...A higher chance for convection once again later Thu aftn/Thu night across the N, then shifting S on Fri with the next cold frontal passage. Mainly dry/VFR for Sat. && .MARINE... As of 330 PM EDT Tuesday... Winds are expected to remain sub-SCA for the next week outside of convection. A few isolated storms will be possible late this afternoon into early this evening, particularly over SE VA/NE NC and may push over the local waters. Otherwise, isolated storms will be possible each afternoon/evening this week. A weak stationary front NW of the local waters will continue to weaken later this afternoon into this evening. Winds this afternoon are SE/S 5-10 kt but will shift to W/WNW late tonight as the weak stationary front pushes SE again before washing out. Another diurnal wind shift is expected Wed as winds shift from W in the morning to S/SE onshore flow in the afternoon. S/SSE winds 5-10 kt continue through Thurs over the Ches Bay/rivers with 10-15 kt winds by the afternoon over the coastal waters. Winds become SW 10-15 kt Thurs evening into early Thurs night as a cold front begins to push south over the local waters. By late Thurs night, winds become W 10 kt, eventually becoming NW 5-10 kt by late Fri morning before turning to N Fri afternoon. The strongest CAA surge behind the cold front is expected to lag until Fri night through Sat morning with N winds 10- 15 kt. Seas of 2-3 ft and waves of 1-2 ft continue through late week. By late Thurs night, seas of 3-4 ft and waves of 2-3 ft will be briefly possible. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...LKB/MAM NEAR TERM...LKB/MAM SHORT TERM...LKB LONG TERM...LKB/MPR AVIATION...LKB/MAM MARINE...RMM/TMG
Area Forecast Discussion
National Weather Service Gaylord MI
1142 PM EDT Tue Jul 27 2021 .UPDATE... Issued at 932 PM EDT Tue Jul 27 2021 With the loss of the heat of the day, we should be losing the chances for showers and thunderstorms. The satellite and radar trends would support this as well as the models. So the focus now shifts to the possibility of fog. currently the grids have patchy fog in them, with areas of fog possible toward 12z, with some locations. If you use the UPS method for fog, with the fact that the winds will be calm and the skies clear, we should have fog around the region. Winds look like they stay light enough to continue into the morning (past 12z) limiting the mixing until the sun can break through. && .NEAR TERM...(Through Tonight) Issued at 312 PM EDT Tue Jul 27 2021 ...Convection possible in spots thru this evening... High Impact Weather Potential...a few strong t-storms possible into early evening. An old outflow boundary has settled just south of the forecast area, while a more traditional w-e synoptic front has drifted down to M-32. A fair bit of cu away from Lake MI, but the most widespread lower clouds over ne lower MI (near APN) has a capped look on sat imagery. Things are more bubbly further south, toward and south of OSC, and radar is showing a few blips down that way. Onshore lake breezes are seen at OSC and Tawas, and with light westerly synoptic breezes inland, convergence is maximized along that lake breeze boundary. Do still expect some convection to fire in se sections this afternoon and evening. MlCape values have risen above 500j/kg, and Cin is reduced below 25j/kg. HRRR and Rap runs both ignite precip in this area. These will have a minimal time to evolve before they move over the somewhat more stable air behind the lake breeze front. A few stronger storms with gusty winds will be possible, but svr might be a stretch. Congested cu are also over Canada, north thru east of the Sault. Given expanding outflow boundaries, there is a small chance for a shower to clip parts of the St Marys River. Further west, cu continue to develop in the zone between the slowly converging lake breezes in central/western Chip/Mack Cos. This is also an area where showers and perhaps a t-storm may still form into this evening. And also, like yesterday, convection could also fire late this afternoon and early this evening in the MNM area. MlCape values are near 1k j/kg here. Se-ward movement of these cells could try to bring activity into the MBL area again this evening. Clearing skies and light winds overnight will contribute to some fog, probably more so than we`ve seen over the past few nights. Min temps will range from the mid 50s north to around 60f south. && .SHORT TERM...(Wednesday through Friday) Issued at 312 PM EDT Tue Jul 27 2021 ...Shower/Storm Chances then Cooler... High impact weather: Strong to severe storms possible Wednesday night. Low pressure moving across central Canada will swing a cold front across the region Wednesday night into early Thursday. This system will likely bring scattered showers and perhaps a few thunderstorms across northern Michigan mainly Wednesday night (but perhaps lingering into Thursday morning as well). The next question is the potential for severe storms as winds aloft are respectable (0-6 km bulk shear 40 to 45 knots). In addition, will have to monitor a possible ongoing MCS which most likely tracks across eastern Minnesota and central Wisconsin. A majority of guidance keeps much of the instability to our south so am not too enthused about the severe weather potential across northern Michigan at this point but will have to keep an eye on latest guidance trends. Heavy downpours are possible with precipitable water values increasing to between an inch and 1.5 inches. Humidity levels will increase once again during the day Wednesday into Wednesday night then begin to drop Thursday with lower humidity expected Friday. Highs in the low and mid 80s Wednesday, the mid 70s to low 80s Thursday and the mid and upper 70s Friday. Lows in the muggy low and mid 60s Wednesday night then the cooler low and mid 50s Thursday night. .LONG TERM...(Friday night through Tuesday) Issued at 312 PM EDT Tue Jul 27 2021 ...Cooler and Less Humid... High impact weather potential: Low. Classic ridge west, trough east pattern across the lower 48 is expected to lead to cooler temperatures and relatively low humidity levels through the period. An upper level disturbance moving through the flow will bring shower chances (possibly a thunderstorm?) Saturday. There could be additional disturbances moving through the flow during the period but pinning down exactly when is up in the air so will leave out pops for Sun-Tue for now (but don`t be surprised if we end up adding some later). Highs are only expected to range from the upper 60s to mid 70s with lows in the upper 40s to mid 50s. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1140 PM EDT Tue Jul 27 2021 Fog looks like it will be an issue early Wednesday morning as low temperatures will fall to around 4 to 6 degrees below the dewpoints during the warmest part of the day, with calm winds, and relatively clear skies over most of N Lower and E Upper, will expect that patchy fog, that would be MVFR VSBY will start, and then progressively have areas of fog, that would drop into IFR VSBYs, and maybe with LIFR CIGs. Will, of course watch and evaluate this over the next few hours, and amend accordingly. MBL is the most likely TAF site to run into this problem, and TVC the least, with APN and PLN likely to run into issues similar to MBL during the morning hours on Wednesday. With the high over the region, winds don`t look like they pick up much during the day, so with the lack of mixing, MVFR VSBYs are possible through the day. && .MARINE... Issued at 312 PM EDT Tue Jul 27 2021 Light winds and minimal wave action expected, as a broad and diffuse frontal zone is hung up across northern MI. There will be an increasing southerly breeze late Wednesday, before a system finally moves thru. Winds will veer w and nw by late Wed night and Thu, and again will be a bit gusty. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...JL NEAR TERM...JZ SHORT TERM...AS LONG TERM...AS AVIATION...JL MARINE...JZ
Area Forecast Discussion
National Weather Service La Crosse WI
628 PM CDT Tue Jul 27 2021 .SHORT TERM...(This evening through Wednesday) Issued at 302 PM CDT Tue Jul 27 2021 At 2 PM, scattered storms continue to develop along the Mississippi River. This is due to the low level convergence and little capping aloft in this area. With favorable 0-6 km shear, there may be even a few supercell thunderstorms. The main threat will be large hail. Temperatures ranged from 76F at Medford to 88F in Charles City IA. For late this afternoon and evening, a shortwave trough, currently located over eastern South Dakota, will move southeast through the area. There several different model solutions on how this convection may develop. The NAM 4 km NEST and ARW suggest that this convection will develop along a west-east boundary in between Interstates 94 and 90. The FV3 keeps the area dry. Finally, the HRRR suggests that storms will develop near the Mississippi River. At this time, I am leaning more toward the HRRR solution. How widespread the convection becomes will depend on how much recovery we can occur during the remainder of the afternoon. Due to this uncertainty, kept rain chances in the 20 to 30 percent range. With 0-6 km effective shear in the excess of 40 knots, there will be a large hail and potentially a damaging wind threat. Another weak wave will move through the area late tonight and Wednesday morning. At this time, it continues to look like the convection will be scattered. With weak shear, not expecting any severe weather with this system. Behind this wave, there will be a surge east by the ridge west of the Mississippi River. 700 mb temperatures will climb into the 12 to 14C range. This strong capping will likely inhibit convection in this area, and it will allow 0-1 km ML CAPES to climb into the 2500 to 4000 J/kg range. Moderate to strong moisture transport into Wisconsin ahead of another much strong shortwave trough will bring some of this instability into western Wisconsin. With 0-6 km shear over 40 knots in Wisconsin, expect any initial convection to be supercells and favor large to very large hail. As the cold pools congeal, expect a squall line to race southeast and south across Wisconsin. This would likely develop during the late afternoon/evening. Besides the severe weather threat, heat indices south of Interstate 94 will climb into the 100 to 105 degree range. As a result, there will be a need for a Heat Advisory. There were even a few places in northeast Iowa where the heat indices may even get into the 105 to 110 range. Probably too small of an area for an Excessive Heat Warning. .LONG TERM...(Wednesday night through Tuesday) Issued at 302 PM CDT Tue Jul 27 2021 Wednesday night looks to be the main period of interest in the long term period with a severe weather threat contingent on whether storms initiate. Still a strong thermal ridge over the nation`s mid- section with our area in the northern periphery with northwest flow. A front will still be hanging out somewhere in the area Wednesday evening, most likely between the Mississippi River and the I-94 corridor. By evening, it looks like a surface low will drop from the Twin Cities metro into west-central Wisconsin, accompanied by some loosely organized mid-level energy rippling through aloft. Also a developing low level jet nosing into central Wisconsin with strong moisture transport. Overall forcing looks to be greatest along and east of the Mississippi River. As these features drop into the area, they will encounter a formidable cap in place with 850mb temps up to 25C. However, an elevated mixed layer will yield favorable mid- level lapse rates in excess of 8C/km. A rich supply of instability, mostly elevated, will be available for storms to tap into IF forcing ends up being adequate to overcome the capping. HREF suggests a high likelihood of 2000-4000 J/kg MUCAPE persisting into the evening given the abundance of moisture and hot daytime temperatures. CAMs indicate convection initiating along the Minnesota/Canada border around midday Wednesday, then bring the MCS southeastward into northern Wisconsin by early evening. As the activity continues to roll southeastward, CAMs keep bulk of it focused along and east of the MS River in tandem with placement of strongest forcing and weakest capping. In fact, most solutions suggest dry conditions along and west of US 63. A lot could still change between now and then depending on how any earlier rounds of convection affect location of the boundary. But there is definitely potential for severe weather if storm complex manages to initiate as models suggest. Bulk shear from 0-6km ranges from 45 to 65 knots east of the MS River, suggesting potential for some supercells at least initially before activity transitions into a forward-propagating MCS. Main threats look to be large hail and damaging winds. Perhaps a small tornado risk given favorable helicity and the boundary somewhere in vicinity, but degree of stability in the low-levels casts some doubt. Certainly a torrential rainfall threat given anomalous PWATs and a deep warm cloud layer, but flooding threat should be tempered somewhat by fairly progressive MCS motion. We then trend towards somewhat cooler, less humid, and drier conditions Thursday and beyond as strong Central Plains ridge is suppressed further south by deepening Hudson Bay trough. Highs generally look to range from the mid 70s to mid 80s with daytime dewpoints largely in the 50s and 60s. Not looking like much for rain potential aside from an incoming shortwave/front on Saturday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 628 PM CDT Tue Jul 27 2021 As of early evening, all the convective activity has ended across the area leaving behind just some high level clouds and VFR conditions. A small chance that some activity could develop this evening as a weak short wave trough moves across the area. A couple of the hi-res meso-scale models do show some development, but confidence not high enough to include for now, but will quickly update if activity does develop. More activity may develop late tonight over western Minnesota and then roll southeast across the region in a weakening state. Other than the HRRR, the hi-res models show not much more than sprinkles from this activity or it misses the airports. Again, confidence not high enough to include at this time. More convection is expected to develop late Wednesday afternoon, but at this time, this looks to be east of both airports. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Heat Advisory from 10 AM to 9 PM CDT Wednesday for WIZ032>034- 041-042-053>055-061. MN...Heat Advisory from 10 AM to 9 PM CDT Wednesday for MNZ079- 086>088-094>096. IA...Heat Advisory from 10 AM to 9 PM CDT Wednesday for IAZ008>011- 018-019-029-030. && $$ SHORT TERM...Boyne LONG TERM...Kurz AVIATION...04
Area Forecast Discussion
National Weather Service Quad Cities IA IL
813 PM CDT Tue Jul 27 2021 .UPDATE... Issued at 804 PM CDT Tue Jul 27 2021 Convection is starting to fire in southeast MN this hour, in line with the 23Z HRRR which develops a small cluster of storms up there which follows the CAPE gradient and drops into northeast IA. Weak pressure falls and weak surface convergence are supporting development now, and expect low-level jet support to develop soon too. Thus SPC watch issuance which includes our Highway 20 counties looks reasonable, especially given the very large hail that environment produced earlier today. Fortunately as storms dive further south out of the watch area, they should weaken quickly as they encounter the drier air to the south of the watch area over east-central Iowa. && .SYNOPSIS... Issued at 248 PM CDT Tue Jul 27 2021 Weather was mixed across eastern Iowa, northwest Illinois and northeast Missouri early this afternoon. Areas generally east of a Cedar Rapids IA toe Galesburg IL line were under mostly cloudy skies, which we the remains of morning convection that occurred over northeast Iowa and southwest WI (storms that produced baseball hail near LaCrosse!). To the west, skies were void of any clouds with south to southwest winds ushering increasing moisture levels into the area. Temperatures were in the upper 80s to low 90s with dewpoints in the mid to upper 70s. This air mass will continue to advance eastward, and will be in place across the area for the entirety of the short term period. && .SHORT TERM...(This Evening through Wednesday Night) ISSUED AT 248 PM CDT Tue Jul 27 2021 [Key Messages] *Hot and humid Wednesday with PM heat index values of 100-105; locally higher values possible *Threat for showers/storms during the morning and and late afternoon & evening; slight risk for severe storms in northwest Illinois [Discussion] Main concerns for the short term period will be the heat and humidity, and chances for showers & storms Wednesday. Very broad surface high pressure centered over Illinois and Indiana has kept our weather quiet over the past few days. Through the short term, this high is forecast to slowly sag south into the Ohio River Valley and mid-Mississippi River Valley, allowing a train of disturbances and surface cold front to move into the area. Thanks to the surface high and the presence of a strong cap aloft, much of the area will see dry conditions for the short term, especially southeast Iowa, west central Illinois and far northeast Missouri. Things get tricky to the north where the cap is weaker and shortwaves/impulse aloft are more prevalent. There are several chances of showers/storms across the area Wednesday. The first comes mid-morning Wednesday as CAMs show a complex of showers and storms from south central Minnesota riding the instability gradient into the area. There are disagreements on whether that complex will survive the trip south, and like today may be tied to the LLJ. If this holds true, then the 12z HRRR is likely the most favored solution of what will happen, which shows a gradually decay with showers and storms as they move towards the Hwy 20 corridor. More aggressive solutions like the RAP advertise more widespread showers and storms, but this has a history of overdoing lift and moisture in these sceneries. Once the complex decays, clouds will stick around before gradually dissipating by the afternoon. Once this happens, temperatures will soar into the low to mid 90s, with dewpoints climbing into the mid to upper 70s as moisture pools ahead of a southward advancing cold front. This will push PM heat index values in the 100-105 range, with potential for locally higher values where maturing crop concentration is higher. I have collaborated to expand the heat advisory CWA wide as confidence has increased with this package of meeting criteria across northwest Illinois. In addition, the heat advisory has been extended for counties along and south of I-80 through Wednesday night into Thursday, with heat indices expected in the 100 to 105 range again Thursday afternoon. The next chance for showers and storms arrives Wednesday evening and overnight ahead of the cold front and a more potent shortwave moving into the northern Great Lakes. A large complex of showers and storms will develop in central Minnesota and western Wisconsin, with the track progged in northern Illinois into the night. Areas in our northwest and north central Illinois counties will have the highest chance of precip and potential for severe storms. As of this writing, the Storm Prediction Center has a Level 2 (slight risk) for severe storms in this area, with a Level 1 (marginal) risk extending further west into far eastern Iowa and northwest Illinois. The main concern will be damaging winds, as discrete cells initially consolidate via cold pools into a line of storms as they move south. The threat of large hail and tornadoes is lower, and is greater into Wisconsin with more discrete activity. .LONG TERM...(Thursday through Tuesday) ISSUED AT 248 PM CDT Tue Jul 27 2021 [Key Messages] *Hot and humid for areas along and south of I-80 Thursday with heat index values of 100-105 *Threat for showers/storms continues into the weekend; low threat for severe storms in southeast Iowa, west central Illinois and far northeast Missouri Thursday. *Reprieve from the heat with daily highs in the 70s/80s and lows in the 50s/60s beginning Friday and lasting through next week [Discussion] Heat and humidity will stick around for one more day before a more pleasant summer air mass moves into the area in time for the weekend. Northwest flow will increase after a cold front passes through the area Thursday afternoon and evening, ushering in 925-850 temperatures near to below 20 celcius through early next week. This will translate to daily highs in upper 70s/mid 80s, and overnight lows in the 50s/60s this weekend into early next week. Dewpoints dropping into the 50s/60s will mean a nice break from the humidity as well! We will have a few chances of showers and storms as the front will stall briefly near the Iowa/Missouri border Thursday and Friday. With the strong heating and forcing along the front, storms should have no trouble firing over our far south. The Storm Prediction Center has a Level 1 (marginal) risk of severe storms over far northeast Missouri and west central Illinois Thursday, but confidence on this is low and directly tied to where the front stalls. If storms develop over our area, the main concerns will be damaging winds and large hail. Chances for precipitation decrease after Sunday, with high pressure providing dry condtions through mid- next week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening) ISSUED AT 641 PM CDT Tue Jul 27 2021 VFR conditions with light winds will prevail through the forecast period. There is a low chance of thunderstorms near the Dubuque terminal tonight and again tomorrow, but chances are too low to include in the forecast at this time. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...Heat Advisory from 11 AM to 10 PM CDT Wednesday for Benton- Buchanan-Clinton-Delaware-Dubuque-Jackson-Jones-Linn. Heat Advisory from 11 AM Wednesday to 8 PM CDT Thursday for Cedar-Des Moines-Henry IA-Iowa-Jefferson-Johnson-Keokuk-Lee- Louisa-Muscatine-Scott-Van Buren-Washington. IL...Heat Advisory from 11 AM to 10 PM CDT Wednesday for Bureau- Carroll-Jo Daviess-Putnam-Stephenson-Whiteside. Heat Advisory from 11 AM Wednesday to 8 PM CDT Thursday for Hancock-Henderson-Henry IL-McDonough-Mercer-Rock Island- Warren. MO...Heat Advisory from 11 AM Wednesday to 8 PM CDT Thursday for Clark-Scotland. && $$ UPDATE...Wolf SYNOPSIS...Speck SHORT TERM...Speck LONG TERM...Speck AVIATION...Wolf
Area Forecast Discussion
National Weather Service Grand Forks ND
908 PM CDT Tue Jul 27 2021 .UPDATE... Issued at 908 PM CDT Tue Jul 27 2021 Still playing the waiting game. The SPC meso page shows the area with the most MLCAPE/no CIN across southern Minnesota, where a large storm east of Rochester is tracking southeast. A weak 20 to 25 knot low level jet is currently across western South Dakota, focused into the ND/SD border region south of Bismarck. The regional radar loop shows nothing in this region yet. The latest HRRR shows a few showers/storms developing over southeast ND in the 2-4 am time frame, but no model run has been very consistent with the timing or placement of any convective activity overnight. UPDATE Issued at 654 PM CDT Tue Jul 27 2021 Lots of smoke and high level clouds are drifting across the FA early this evening. At the moment, the most clouds are west of the Red River Valley. The regional radar display is also picking up on fairly widespread returns, but surface observations are showing no clouds below 12,000 feet and nothing is reaching the ground. 700mb temperatures are quite warm where these clouds and radar echoes are, or +12 to +14C. So it is likely going to take until later this evening, when the low level jet starts to increase, before some shower and storm activity might get underway. The latest model data shows that by midnight, the low level jet focus may be into the Bismarck area. By 4 am, this starts to turn more southwesterly, and begins to focus into southeast North Dakota. So at this point, it is looking like an overnight event, although uncertainty remains high. And for this FA, the best potential looks to be over southeast North Dakota into adjacent portions of west central Minnesota. This is not going to be widespread rain event, with any higher amounts tied to any thunderstorm tracks. && .SHORT TERM...(This evening through Wednesday night) Issued at 302 PM CDT Tue Jul 27 2021 Focus within the short term will be thunderstorm chances tonight into Wednesday, some of which may produce hail to the size of golf balls and gusty winds up to 60 mph. This afternoon, a wedge of surface high pressure centered over ON will keep the area dry (with help from elevated smoke). This wedge of high pressure will slide east tonight allowing return low level south-southwesterly flow into the region this evening. This will help push a stationary front northward into the southern CWA as a warm front. This comes ahead of an incoming shortwave trough within broader northwest flow aloft. The shortwave will promote the development of a LLJ over the warm front into southeast ND and RRV tonight. South of the warm front is a pool of elevated, unstable air. With elevated weak to moderate instability and forcing from LLJ/warm front combo, thunderstorms are expected to develop overnight tonight. Additionally, strong shear will be in place composed of a veering and increasing wind profile, maximized near the LLJ. This wind shear will bring the chance for robust updrafts. With the anticipation of elevated convection tonight due to warm low level temps, hail would be main concern. Given the magnitude of shear, it wouldn`t be surprising to see elevated supercellular structures capable of producing hail to the size of golf balls. Currently favored location for severe convection resides near the SD border, although confidence is not as high. Expectation is for storms to continue into Wednesday morning before moving east deeper into Minnesota. There is still a chance for additional thunderstorm development in the afternoon behind morning convection within Minnesota as a cold front/surface low moves through, although will depend on timing of cold fropa and amount of daytime heating behind morning storms/clouds to overcome capping. Will similar thermodynamic and kinematic environment in place ahead of the front, afternoon storms may be severe,large hail and high winds being main threats. Otherwise tomorrow will be the last hot day with heat indices in the mid to upper 90s, especially near the tri-state area. .LONG TERM...(Thursday through Tuesday) Issued at 302 PM CDT Tue Jul 27 2021 The extended time frame features more of the same with respect to dry conditions with ensemble guidance suggesting temps to cool closer to normal for the end of July and beginning of August. As for the precip, the next chance in the forecast will be associated with a short wave traversing the northern plains either late Friday or Saturday. Again not a widespread rain maker but some showers and storms will be possible as the wave interacts with some moderate instability. Then chances dry up as western conus ridging and eastern conus troughing amplifies into the next week with SFC ridge axis persisting under the nearly northerly and diffluent flow aloft across the northern plains. As a result of the pattern shift our 500mb thicknesses do decrease some and shunt the warmer air to the west allowing a more seasonable temp regime with highs in the 80s valley west and 70s in the MN trees and lakes country with lows in the 50s. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 654 PM CDT Tue Jul 27 2021 Any storm activity over the next 24 hours is highly uncertain, so elected not to mention any at any of the TAF sites. If something indicates more certainty for a TAF site, will update then. Otherwise, the main story will be shifting wind speeds and directions over the next 24 hours. The most impactful period will be behind the north wind switch by Wednesday afternoon. Winds will get pretty gusty during the afternoon period, especially along and west of the Red River Valley. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. $$ UPDATE...Godon SHORT TERM...CJ LONG TERM...JK AVIATION...Godon
Area Forecast Discussion
National Weather Service Indianapolis IN
1147 PM EDT Tue Jul 27 2021 ...Updated Aviation Discussion... .Forecast Update... Issued at 1011 PM EDT Tue Jul 27 2021 Mostly clear skies expected for much of the night based on satellite loop, with some mid and high cloud debris arriving late overnight/near daybreak from convection to the north. Going low forecast in the upper 60s to around 70 look on track. May see some patchy fog in low lying areas with dew points right now in the mid 60s to lower 70s and likely to stay near there. However, boundary layer dew point depressions are still staying up in the 4 to 7+ degree range, indicating there is still some mixing and dry air in the boundary layer if not at the surface, so think any fog should remain pretty isolated (ie patchy fog in a few low lying areas) and thus will continue to leave out of the grids. No significant changes to the going forecast. && .Short Term...(This Evening through Wednesday Night) Issued at 258 PM EDT Tue Jul 27 2021 Another toasty afternoon for the region with a noticeable increase in the haze over Monday as more smoke aloft has drifted into the region. 1830Z temperatures were in the mid and upper 80s but humidity levels were again manageable today and keeping heat indices from peaking much higher than the lower 90s. Much of the next roughly 36-40 hours is setting the table for what is likely to be a rather active Thursday on multiple fronts. That will be focused on in much greater detail in the long range discussion below. Through Wednesday night...the upper level pattern will shift slightly as the core of the broad ridge focused over the central Plains gradually shifts south and east. While central Indiana will remain on the periphery of the ridge through Wednesday night...mid level heights will rise due to the shift of the ridge core. This will result in potentially hotter temperatures for much of the region Wednesday. At the surface...high pressure will remain a dominant influence across the Ohio Valley through late Wednesday. For tonight...may see sporadic mid and high level clouds drift through the region from convective cluster remnants over the upper midwest. In general...skies will be mostly clear with haze levels falling back as the higher smoke concentration shifts south of the region this evening. The HRRR vertically integrated smoke parameters look to increase again on Wednesday as another surge of greater concentrated smoke extends into the region...although the highest levels of smoke should largely remain to the northwest. Expect another day with plenty of sunshine. Model soundings do show a greater potential for diurnal cu as low level moisture advection begins. While much of Wednesday should see tolerable humidity levels again...a transition to southwesterly low level flow by late day will enable much higher dewpoints in the 70s to spread back into the forecast area by late day and into Wednesday night. This will set up the potential for an oppressively muggy airmass for Thursday ahead of the cold front and expected robust convective development. The final issue for the short term and the one that is likely to have the greatest impact on just exactly how Thursday plays out focuses on the expectation of a mesoscale convective complex to organize across the upper Midwest Wednesday evening in tandem with a strong upper level wave. Trajectories support a southeast moving cluster that will likely produce severe weather Wednesday night aided by an impressive near 50kt 850mb jet. The general movement on the system would bring it into N/NE Indiana during the predawn hours Thursday with at least some potential that the tail end of the cluster works south into part of the northern forecast area. Considering the possibility that this system will mature enough to develop a cold almost anticipating that the convection will develop further back on its southwest flank into parts of central Indiana near daybreak Thursday. The questions that remain far S/SW into the forecast area the storms can make it Thursday morning and what intensity will they have when they arrive? The nocturnal jet will weaken by 12Z Thursday and largely remain to the north of central Indiana. That would suggest that if the convective complex becomes cold pool some point the storms will outrun their low level fuel source...weaken and eventually diminish. At this point...that will likely take place somewhere across the northern half of the forecast area Thursday morning. Still a lot of details to work out...but there is some merit that this could serve as the initial salvo in a 1-2 convective punch for the region by leaving a leftover boundary for new storms to fire on later on Thursday. It also presents some uncertainty with how much convective cloud debris departs Thursday morning and how that might impact available instability for new storms later in the day. Much more on this in the long term section below. Temps...low level thermals are a touch warmer on Wednesday with solid potential for temperatures to peak in the low to possibly mid 90s. Lows will fall into the upper 60s and lower 70s tonight with low to mid 70s and noticeably more humidity for Wednesday night in advance of what is shaping up to be a hot and very humid Thursday ahead of the storms. && .Long Term...(Thursday through Tuesday) Issued at 258 PM EDT Tue Jul 27 2021 Thursday... Early in the long term, the focus will be on the advancement of a positively tilted mid level trough of which should initiate a MCS over the Upper Great Lakes region Wednesday. The remnants of this potent MCS is expected to pass over northern and eastern portions of central Indiana early Thursday morning, but with a nearly stable surface layer, thunderstorms should remain isolated with scattered light showers more predominant. Eventually the bulk of the mid level moisture should diminish as the trough nears, leaving relatively dry mid levels over a capped surface layer. This should produce a brief lull in rain chances late Thursday morning into the early afternoon hours. Cloud cover midday Thursday will begin to diminish in response to the dry air entrainment creating partly to mostly sunny conditions at times. Temperatures are expected to rapidly increase over this time period with a combination of diurnal warming and warm air advection aided through enhanced SW flow out ahead of the trough. Temperatures should top off in the low 90s, with highest values located in western portions of central Indiana, where prolonged clear skies are more likely. The advection within SW flow will also push dew point temperatures into the mid 70s, creating potentially hazardous heat indices in the low 100s. Some uncertainty still lies within timing of afternoon convection. Initiation is expected to be slightly delayed over western central Indiana, where excessive heat is of most concern. As mentioned previously, thunderstorms are expected to develop over central Indiana Thursday afternoon. The cold pool created by the MCS over the upper Great Lakes is expected to stall overnight Wednesday somewhere over north to north central Indiana, resulting in a quasi- stationary boundary. This feature will be the main source of lift for convective initiation. Thermodynamic profiles depict plenty of buoyant energy in the mixed layer, supported my 3-6km lapse rates above 7 C/km. This should allow for initiation to begin shortly after surface temperatures/dew points are high enough to break a weak WAA cap (50-100 J/kg CIN). Current expectations are for this to occur during within the early afternoon hours from east to west along the boundary. A surface environment of around 91/75 (T/Td), in conjunction with steep mid level lapse rates will produce MLCAPE values near or even above 3000 J/kg, plenty enough for deep, robust updrafts to develop. This along with Effective Bulk Shear values of around 30kts should support organized convection, especially along the aforementioned boundary. DCAPE values around 1000 J/kg, and theta(e) index (TEI) values well above 10 support the idea of possible damaging winds within organized convective structures and will be the primary severe threat with this event. Some bows/surges will be possible within convective lines given SFC-3km shear near 30kts, and with this creates the possibility for isolated tornadoes. There is still plenty of uncertainty with the timing and location of initiation with this event, as upstream convection on Wednesday will play a major factor. Thursday Night through Monday.... Much cooler air will push into the Ohio Valley following the passage of a cold front and associated thunderstorms. Overnight temperatures should fall into the mid to low 60s. CAA will continue to lower low level temperatures heading into Friday. Even with high pressure induced clear skies, temperatures shold top[ off in the low 80s, with much more pleasant dew points in the low 60s. High pressure is expected to stick around for Saturday, keeping similar, dry conditions. Weak short waves within NW flow could bring slight chances for showers and thunderstorms on Sunday and Monday, but some dry air entrainment from the high to the SE could limit shower development. Without any significant advection present, overall temperatures should remain similar with highs in the low 80s. && .Aviation...(06Z TAF Issuance) Issued at 1146 PM EDT Tue Jul 27 2021 IMPACTS: - mainly VFR conditions through the period - outside chance for patchy ground fog at outlying sites - winds less than 4 kts through the overnight DISCUSSION: High pressure will continue across central Indiana through the rest of the night and much of Wednesday. Leftover mid and high level clouds from convective complexes over the upper Midwest may occasionally drift across the sites into Wednesday. With ample low level moisture could see some patchy ground fog, but don`t expect it to be prevailing and too low of confidence in location/timing to include. Should see few to scattered cu develop Wednesday afternoon AOA 4kft. Winds will largely be light and variable through the overnight hours, but could have a westerly component. Winds should be less than 10 kts out of 270 to 290 from midmorning Wednesday through Wednesday evening. Could see some convection move in from the northwest late Wednesday night, but low enough confidence to leave out at this time. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ Update...CP Short Term...Ryan Long Term...Updike Aviation...CP
Area Forecast Discussion...UPDATED
National Weather Service Baltimore MD/Washington DC
926 PM EDT Tue Jul 27 2021 .SYNOPSIS... A weak frontal zone will remain draped near or over the Middle Atlantic through Wednesday, reinforced by disturbances aloft. A stronger cold front will cross the region Thursday into Friday. High pressure will follow for the first half of the weekend before another frontal boundary approaches by early next week. && .NEAR TERM /THROUGH WEDNESDAY/... An isolated shower has developed over Augusta County this evening. Hoping that this is short-lived as there is an abundance of dry air per 00Z IAD RAOB. A thicker layer of smoke was also seen right around sunset over southern PA and western MD progressing southeast. Mainly clear, but hazy skies are expected overnight with lows ranging from the mid 60s in the mtns to the mid 70s along the bay. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... A shortwave trough currently over Saskatchewan in Canada is expected to cross the region Wednesday afternoon. This should enhance the pre-existing frontal zone/lee trough (possibly merging with another weak front/surface reflection). Lift from these features will act on the instability present to result in scattered afternoon and evening showers and thunderstorms. Modest flow aloft may lead to some loose organization, perhaps resulting in a focused cluster/corridor or two of gusty to damaging winds, but certainty in specifics is low a day in advance given the overall marginal environment for organization. Notably, the 12z HRRR mixes dew points to around 50 during the afternoon, whereas as the NAMNest holds dew points in the mid 60s (as does most other guidance). This plays a big role in available CAPE and subsequent depth of convection. Regardless, very steep lapse rates in the lower levels and ample DCAPE should result in an environment favorable for strong downdrafts/bursts in the stronger cells. A much more potent (convectively augmented) shortwave trough and accompanying mid-level speed max are expected to pivot across the area Thursday afternoon. There are uncertainties in the extent of upstream convection and clouds which may temper instability, though the 12z guidance overall has trended higher with projected instability/CAPE. The seasonably strong trough and wind field with moderate to strong CAPE may result in one or more clusters of organized thunderstorms (perhaps initiating as more discrete cells for a time) capable of damaging wind and hail, heavy rain/flooding given high humidity, and even a tornado threat. The extent of severe weather will be highly dependent on the evolution of upstream convection over the next 48 hours as well as the magnitude of instability locally. Overall, the threat is marginal at this time due to low confidence, but with a high ceiling; a worst case scenario would be one where widespread gusty to damaging winds are observed due to the favorable background environment. Temperatures should run a little above normal Wednesday through Thursday before heat and humidity take a tumble behind the front by the end of the week. && .LONG TERM /FRIDAY THROUGH TUESDAY/... A few isolated showers are possible across our southern zones and bay waters both Friday afternoon and again Saturday evening with a weak boundary nearby. Otherwise, the weekend looks slightly cooler by a couple of degrees compared to previous days with highs in the middle to upper 80s. The warmer day appears to be Friday. Later Sunday into Monday would be the next better chance of showers and thunderstorms as a cold front pushes in from the northwest and nearly stalls to the south by later in the day Monday. High temperatures will approach 90 ahead of the front but could be held in the middle to upper 80s in any cloud cover and convection. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... Mainly VFR conditions are forecast through the end of the week, with a few potential exceptions: (1) Patchy fog may encroach on the CHO/MRB terminals 8-12z Wed (2) TSRA potential both Wed PM and Thu PM w/ gusty wind possible Otherwise, flow will be somewhat erratic in direction with multiple weak frontal boundaries nearby, and river/bay breeze influences for DCA/BWI/MTN during the afternoon and evening. Any shower activity could pose an MVFR threat near CHO and possibly DCA Friday and Saturday. Otherwise, VFR conditions. Winds generally northwest 10 to 15 knots gusts up to 20 knots Friday, becoming northwest around 5 knots Friday night. Winds northwest 5 to 10 knots Saturday, becoming southwest then south around 5 knots Saturday night. && .MARINE... Through early Thursday, wind outside of convection should stay under SCA levels. There is some increase in southwesterly winds expected on Thursday which may require a SCA for portions of the waters. A better chance for thunderstorms exists on Wednesday and Thursday, with Special Marine Warnings possible. A Small Craft Advisory is possible Friday. Winds northwest 10 to 20 knots w/ higher gusts Friday. Winds diminishing northwest 5 to 10 knots Friday night and Saturday, becoming south 5 to 10 knots Saturday night. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...DHOF NEAR TERM...LFR SHORT TERM...DHOF LONG TERM...KLW AVIATION...LFR/KLW MARINE...LFR/KLW
Area Forecast Discussion
National Weather Service Pendleton OR
854 PM PDT Tue Jul 27 2021 .UPDATE...The latest radar was showing a plume of moisture from central Oregon that stretched into south central Washington. This area of mostly rain showers had been slow to move eastward. The rap and hrrr models have these rain showers drifting east tonight while slowly dissipating. Meanwhile some isolated showers were developing even more ahead of this area over Grant county. Portions of the pcpn should slowly migrate into the eastern sections of our area overnight. Due to the extensive cloud over today thunderstorm activity had been limited and the forecast was updated to reflect this overnight. Also the pops were adjusted along with the location of the pcpn to better reflect the current and projected movement overnight. Minor changes were done to low temps that are forecast mostly in the 60s with 50s in the mountains and now the present short term forecast appears on track. && .PREV DISCUSSION... /issued 458 PM PDT Tue Jul 27 2021/ SHORT TERM...Tonight through Thursday...Band of showers continues to impact areas of central OR northeast into the WA Columbia Basin this afternoon, with very little lightning being produced in these showers. Showers across these areas will persist into the evening as the band moves east across the Blues and into Wallowa county. Areas that see lingering cloud cover tonight will likely see warmer morning lows tomorrow, with possible muggy conditions where surface moisture lingers. Tomorrow, upper ridge will begin to amplify over the region with a noted warm-up into this weekend. Overnight lingering showers will diminish tomorrow morning across the forecast area as dry air aloft swings around upper high pressure. That said, monsoonal moisture across southern and into portions of central OR will allow for the development of isolated storms in these areas in the afternoon. Thursday, upper ridging centered over the northern Rockies will continue to amplify, allowing for warm air advection into the PacNW. By Thursday afternoon, many locations will see afternoon temps in the upper 90s to 104. That said, cloud cover from potential thunderstorms across southern and central OR on Thursday could act to limit some of the daytime heating. Otherwise, overnight lows by Thursday night will not offer much relief, as by sunrise, temperatures will have just cooled to the mid 60s to lower 70s. With this in mind, an Excessive Heat Watch has been issued starting Thursday for elevated heat risk across the lowland areas. As mentioned earlier, the thunderstorm threat will return Thursday afternoon as a weak moisture surge into southern and south central OR is supported by an impulse moving north from CA/NV. Instability associated with this system will be enough for abundant lightning with any storm developing. With the potential for elevated fire weather concerns, a Fire Weather Watch has been issued for a portion of central OR. Otherwise, winds the next couple of days will continue to be locally breezy, especially through the Cascade Gaps. Lawhorn/82 LONG TERM...Friday through Tuesday...A deep upper level ridge is expected to start the extended period over the Central US, stretching across the Rockies and into the PNW. This ridging will reach its peak across our region Saturday; however, moisture and cloud cover should help prevent even higher temperatures from being possible compared to Friday. Triple digit temperatures are expected for the Columbia Basin both days. The aforementioned moisture and an embedded feature in the pattern will then bring much needed rainfall and possible thunderstorms to Central through Eastern OR and Southeastern WA. High PW values could spell periods of heavy precipitation and training activity, which could bring a risk of localized very heavy rainfall. Ensemble models have a good handle on this pattern still with solid agreement moving into the weekend. The ridge should then shift eastward across the Rockies with the center of the upper high retreating into the Four Corners as the trough off California and deep low near Canada push into the coastline of North America. This pattern will help us drop 5-15 degrees across the entirety of the forecast area to begin August, with temperatures seeing a slight increase then on Monday and Tuesday. Ensembles diverge early next week on the strength of both the offshore trough and ridge declining into the Desert SW. The GEFS would allow for a deeper area of ridging and a tighter pressure gradient for our region, while the ECMWF Ensembles have the ridge further south, allowing for more influence from the offshore trough and allow us to remain cooled off longer. Analysis reveals better agreement for the ECMWF deterministic and its ensemble, making it the favored outcome at this time. AVIATION...Isolated showers may effect each taf site overnight except for kykm while some of the heavier showers may lower ceilings to sct-bkn050 especially at kbdn. Also an isolated thunderstorm could approach taf sites krdm and kbdn until 04z. Otherwise mainly vfr conditions should persist for the next 24 hours. FIRE WEATHER...Band of showers observed from central OR up into the Basin will continue through the evening into the early morning hours of Wednesday, with strongest activity expected around central OR. LALs of 2 to 3 with this system, however monsoon moisture will make any storms that develop very wet, partially offsetting lightning ignition chances. Wednesday afternoon onward, storm chances become limited to mostly central OR. Models indicate plenty of instability over the area Thursday, with PW amounts still relatively high, however have elected to issue a Fire Weather Watch for OR611 in light of abundant lightning threat. Moisture over the area today through early Thursday may help wet fuels, however amount of instability forecasted over the area suggests enough lightning to potentially trigger critical fire risks. 74 && .PRELIMINARY POINT TEMPS/POPS... PDT 67 92 64 100 / 30 10 10 10 ALW 71 94 69 102 / 30 10 0 10 PSC 71 98 68 102 / 30 0 0 10 YKM 65 97 66 101 / 10 0 0 10 HRI 70 97 67 103 / 30 0 0 10 ELN 64 94 62 98 / 10 0 0 10 RDM 60 93 57 97 / 30 20 20 20 LGD 65 91 62 97 / 20 10 10 10 GCD 64 94 62 98 / 30 10 10 20 DLS 68 98 69 103 / 20 0 0 10 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...Excessive Heat Watch from Thursday morning through Saturday evening for ORZ041-044-507-510-511. Fire Weather Watch from Thursday afternoon through Thursday evening for ORZ611. WA...Excessive Heat Watch from Thursday morning through Saturday evening for WAZ024-026>029-521. && $$ SHORT TERM...97 LONG TERM....99 AVIATION...97
Area Forecast Discussion
National Weather Service Shreveport LA
1013 PM CDT Tue Jul 27 2021 .UPDATE... Reduced pops and lowered a few overnight low temperatures. && .SHORT TERM... Well the radar is quiet for our area with the last brief thunderstorms seen in southern DeSoto during this update. Elsewhere, a few remaining anvils or raining out with some light rain still in Lufkin. There is still a cluster of activity in the delta about to cross the MS River. This may help touch off some noctural showers for areas well south of I-20 overnight. The HRRR shows little in that way now, but did have some output in previous updates. Our sounding showed a NE direction for all winds aloft. A weak cold front is pulling up stationary over southern Arkansas with it`s air mass core at 1017mb over the boot heel of MO. The models show it to sink just a little farther south so we may see a few sites showing NE wind early, but more like calm or light and variable for most of the area. As such, we still have a mention of patchy fog for the daybreak timeframe. /24/ && .PREV DISCUSSION... /issued 731 PM CDT Tue Jul 27 2021/ UPDATE... Changes to evening pops for E TX primarily with active outflows. SHORT TERM... Weak cold front on approach is plugging into our Easterlies pattern with NE winds aloft now for much of the area and the prevailing direction of movement for convection. Active outflows continue with the remaining surface based cape of 3500-5000J/Kg over E TX. Two areas just north of I-20 and back into NW LA with multiple boundaries. Also the Sabine Parish to Sabine County hand- off across the lake. One last cluster of activity out of Arkadelphia AR, but lots of worked over air lying ahead of that one. We will take a look at overnight lows and fog areas again later this evening. For now needed to update to remove HX headline for today and focus on tomorrow`s. /24/ PREV DISCUSSION... /issued 700 PM CDT Tue Jul 27 2021/ AVIATION... For the ArkLaTex terminals, decent push of convection into the area today with approaching cool front. TX terminals will see the most of any action 01-03Z with an active outflow sagging toward KGGG/KTYR and also a cluster crossing Toledo Bend which could affect KLFK. Toward daybreak we may see some VCSH down that way w/ LIFR FG briefly. A few sites may see IFR/MVFR BR as well with calm. Light and Var. winds will occasionally be ENE5-10KT tmrw. Right now our winds aloft are already NE all the way up. /24/ PREV DISCUSSION... /issued 233 PM CDT Tue Jul 27 2021/ SHORT TERM.../Tonight through Wednesday Night/ For the rest of Tuesday...Latest radar imagery is starting to light up early this afternoon with showers and thunderstorms. Expecting this activity to continue through the afternoon before generally diminishing after sunset. There is a chance that a few thunderstorms could produce a few strong downbursts that will bring gusty winds at times and perhaps some small hail. Surface observations are showing high temperatures ranging from the 80s to upper 90s across the region with heat indices in the lower to mid 100s. The convection and cloud cover could really impact how much warmer we get this afternoon, so while some forecasted highs will be achieved, others may not make it. As mentioned earlier, any showers and thunderstorms that do develop this afternoon will begin to diminish shortly after sunset, with only a few lingering showers possible. PoPs will then begin to increase once again early Wednesday morning across portions of deep east Texas, spreading to adjacent areas in Louisiana through the day. The best chances for showers and thunderstorms on Wednesday will generally be along and south of I-20. Perhaps a few showers will be possible north of I-20, but no farther than the I-30 corridor. Once again, showers and thunderstorms during the day Wednesday will quickly diminish shortly after sunset. As for temperatures, overnight lows will generally be around the mid 70s across the region tonight with a similar rinse and repeat set-up for Wednesday night. High temperatures on Wednesday will once again hover around the mid 90 degree mark across the region. However, couple that with our high dewpoints and once again we will reach afternoon heat indices ranging from 105 to 109 degrees. As such, have maintained our daily Heat Advisory which will go into effect at 17z Wednesday and continue through 00z. /33/ LONG TERM.../Thursday through Tuesday/ Upper ridging centered over the Central Plains will continue to expand southeastward across the region into the Lower MS Valley and across portions of the SE CONUS. This should result in slightly warmer temps and mostly dry conditions for the end of the work week into the first half of next weekend. Some weakness aloft along the Srn periphery of the ridge axis could allow for some seabreeze and isolated afternoon convection during this timeframe, with the best chances along and south of the US HWY 84 corridor of Deep East Texas and adjacent Central Louisiana. Afternoon highs will likely top out in the upper 90s during this period, with some guidance suggesting lower 100s across a large portion of the region. Decided to go conservative a bit and keep highs just shy of that, but some isolated triple digit marks are very possible. It appears that Heat Advisories will be needed as these temps combined with upper 60s to lower 70 dewpoints will keep heat indices near or above 105 degrees. By Sunday, the upper level pattern across the region will start to change. The upper ridge will start to retrograde westward into the Rockies, as a longwave trough begins to dig southward out of the Midwest into the SE CONUS and Lower Mississippi Valley, bringing a weak cool front into Central OK/AR Sunday. This boundary will continue to slowly drop southward into the northern sections of the CWA by Monday and eventually through the entire CWA on Tuesday. Convection is expected to increase along the frontal boundary Sunday, eventually moving into our northern zones by late Sunday afternoon into Sunday evening. This convection will likely continue into Monday and Tuesday, as the boundary slowly moves through the region. There could be some compressional warming ahead of the boundary, which could factor into max temps Monday for areas near the I-20 corridor. But at this time, decided to stay with NBM and keep highs in the low to mid 90s, as cloud cover could offset the compressional heating. Overall, rain and cloud cover should give us lower max temps for the first half of next week, bringing some relief from the heat. /20/ && .PRELIMINARY POINT TEMPS/POPS... SHV 76 96 77 98 / 30 30 10 20 MLU 75 95 77 97 / 40 30 10 20 DEQ 74 96 75 98 / 20 10 0 10 TXK 77 96 77 98 / 20 10 0 10 ELD 72 95 74 98 / 30 20 0 10 TYR 77 95 77 96 / 30 30 10 20 GGG 75 94 76 96 / 40 30 10 20 LFK 72 95 76 96 / 30 50 10 30 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...Heat Advisory from noon to 7 PM CDT Wednesday for ARZ050-051- 059>061-070>073. LA...Heat Advisory from noon to 7 PM CDT Wednesday for LAZ001>006- 010>014-017>022. OK...Heat Advisory from noon to 7 PM CDT Wednesday for OKZ077. TX...Heat Advisory from noon to 7 PM CDT Wednesday for TXZ096-097- 108>112-124>126-136>138-149>153-165>167. && $$ 24/33/20