Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/27/21

Area Forecast Discussion
National Weather Service Cheyenne WY
738 PM MDT Fri Mar 26 2021 .UPDATE... Issued at 737 PM MDT Fri Mar 26 2021 Looking at latest soundings and HRRR guidance...think there may be a chance for fairly widespread fog tonight. We did have pretty dense fog over the Summit into Laramie this we could see it again today. Updates have been sent. && .SHORT TERM...(This evening through Monday) Issued at 338 PM MDT Fri Mar 26 2021 An active pattern underway as a trough transitions through the region as we speak. The cold front associated with this trough is currently draped along the Laramie Range, with light snow showers across southeast Wyoming, and a rain-snow mix falling across the west Nebraska Panhandle. Under the heaviest bands, snow has fallen even as temperatures remain above freezing. This may lead to very slick roads tonight as the ground freezes and the front passes. Liquid amounts are generally under a tenth, except under the the heaviest bands over the Panhandle and across the mountains where a few inches are likely. The front should pass east of the region just after midnight, with some partial clearing in its wake. Patchy fog may be expected and the next shift will take a look at this. Moving into the weekend, we`re looking a warming and drying trend, becoming increasingly windy day by day. Saturday will be dry and near normal with breezy conditions, especially under a strong northwesterly flow over the Panhandle under a northwest flow aloft. However, as the upper pattern transitions to a zonal flow, a few shortwaves will pass through on Sunday, and continue into Monday. This is the first hint that a wind-gap pattern will be underway. Looking more closely at omega fields, lapse rates, and surface gradients, all factors are aligning in what`ll be the next Wyoming wind-gap strong wind event. A Watch has already been issued for the wind-prone areas of southeast Wyoming, but may need to be further expanded as winds become especially gusty on Monday across Carbon County, though gusts 30 to 40 mph will not be out of the norm Sunday and Monday, especially Monday as the next through begins to push into the region and gradients compact aloft. Not only will winds be an issue, but under the ridge sandwiched between today and Monday`s troughs, drying trends will bring relative humidities down, as spike up into the 50s and 60s, about 10 to 15 degrees above normal for this time of year. Fire weather concerns will be heightened during this period. .LONG TERM...(Monday night through Friday) Issued at 338 PM MDT Fri Mar 26 2021 Colder across the CWA Tuesday with sctd rain and snow showers as the main upper trough axis slowly moves across the region. After it does so warmer and dry weather looks to settle across the region for the rest of the week with upper ridging shifting across the region Thursday and Friday. Embedded weak shortwaves in the flow likely to produce some breezy to windy periods across mainly se Wy in the wind-favored areas but latest gradients not all that high. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 534 PM MDT Fri Mar 26 2021 Scattered rain/snow mix continuing across SE WY and W NE keeping everywhere at IFR/MVFR cigs and visibilities. Precipitation looks to clear out of SE WY by 04Z Saturday and W NE by 10Z. But, due to some clearing skies, fog is a possibility, especially in W NE, KLAR, and KRWL early Saturday morning. Conditions should improve to VFR as the winds start gusting and push the fog out by Saturday morning. && .FIRE WEATHER... Issued at 338 PM MDT Fri Mar 26 2021 Light snow showers today (rain across the Panhandle, turning to snow this evening) with the passing of a cold front. Liquid totals will generally come below a tenth over the course of the day. A drying trend will kick in tomorrow and continue through Monday, with a breezy pattern coming into play. Strongest gusts are forecast for Sunday and Monday with gusts to 40 mph possible, and higher across southeast Wyoming`s wind-prone corridors. Look for warming temperatures under this pattern with forecast highs 10 to 15 degrees above normal both Sunday and Tuesday. Haines 6 on Sunday. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...High Wind Watch from Sunday morning through Monday afternoon for WYZ106-110-116-117. NE...None. && $$ UPDATE...GCC SHORT TERM...AB LONG TERM...AB AVIATION...LK FIRE WEATHER...AB
Area Forecast Discussion
National Weather Service Grand Rapids MI
1030 PM EDT Fri Mar 26 2021 LATEST UPDATE... Update .SYNOPSIS... Issued at 300 PM EDT Fri Mar 26 2021 - Low Pressure brings rain Saturday night - Cold front brings chance of rain Tuesday && .UPDATE... Issued at 1025 PM EDT Fri Mar 26 2021 There is a stronger inversion up around 850 mb which has trapped the low level moisture beneath it. Satellite and observational trends show that there are still plenty of clouds around to support a mostly cloudy sky forecast. That was the main change to the forecast for this evening. If it did clear out...we could see low stratus/patchy dense for form then. The HRRR was suggesting that as a possibility. && .DISCUSSION...(This evening through next Friday) Issued at 300 PM EDT Fri Mar 26 2021 - Low Pressure brings Rain Saturday night No hazardous weather expected over the next week with about a quarter inch of rain expected as surface low tracks just south of Lower Michigan. Model soundings show that elevated instability Saturday night is rather marginal but we are currently included in the SPC general thunder area, so thunder is kept in the grids for now. Breezy conditions on Sunday behind the departing low - Cold front brings chance of rain Tuesday night Pretty quiet weather next week except for a strong cold frontal passage Tuesday night, Expect a band of rain with the front. Model soundings show dry air below cloud base which could result in enough evaporative cooling to have rain mix with snow, but this was left out of the forecast for now. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 737 PM EDT Fri Mar 26 2021 MVFR conditions continue to linger across many of the TAF sites. The westerly flow is forecast to draw in somewhat drier air resulting in conditions going to VFR over the next couple of hours. There are some indications that IFR and lower fog may form in any clearing. At this time...that risk is not high enough in Southwest Lower MI to include it in the forecast. We will need to monitor trends closely though. Next up will be an area of showers that tracks in from the west Saturday afternoon. Right now most of those look to contain only VFR conditions...but there is a small risk for a thunderstorm or two later in the day...mainly south of KGRR and KLAN. && .MARINE... Issued at 300 PM EDT Fri Mar 26 2021 Gale Watch has been issued for Sunday as northwest gales are expected on the back side of the departing low pressure. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...Gale Watch from Sunday morning through Sunday evening for LMZ844>849. && $$ UPDATE...MJS SYNOPSIS...Ostuno DISCUSSION...Ostuno AVIATION...MJS MARINE...Ostuno
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
924 PM CDT Fri Mar 26 2021 .UPDATE... 924 PM CDT No major changes to the going forecast and continue to see a potential for scattered strong to possibly severe storms in the southeast half of the CWA -- roughly along/southeast of I-55) -- during the mid-afternoon through early evening. Evening upper air analyses and water vapor imagery indicate a 70 kt 500 mb jet progressing east-northeastward from Kansas, with scattered strong convection having blossomed in that area. As a short wave progresses in this fast-paced mid-level flow, showers and some convection should continue to grow east-northeastward, helped by larger scale ascent, increasing low-level jet, and moisture convergence/f-gen from 850 to 700 mb. There also is an area of steeper mid-level lapse rates of 7.5 to 8C in the 650-500 mb range as seen on the OAX and TOP soundings. This is expected to slowly migrate eastward, and some of the convective activity is likely to outpace this especially as it gets into northern Illinois overnight. Thus the chance of thunderstorms looks low through early morning with mainly showers, with possibly a couple storms in north central Illinois by mid-late morning. The prior AFD speaks well to the rest of Saturday. Higher theta-e air in the lower troposphere will work northward, possibly with the northern nose of the effective warm sector reaching up to the Kankakee River Valley by mid-late afternoon. High values of deep layer shear (0-6 km of 60-75 kt), owing to the strong upper west- southwesterlies, will probably favor some organized, or at least sustained, storm structures should deeper convection be able to trigger. The trend in several convection allowing model solutions, including HRRR runs the past several hours and the 00Z 3km NAM, is that it will, with low-level confluence increasing ahead of the next short wave. The deep layer moisture is a bit marginal upstream on Central Plains and Missouri River Valley soundings, and that along with uncertainties on degree of MLCAPE may trump robust convection coverage at least this far north. An SPC Marginal Risk continues to convey the message well, though as 00Z guidance and more higher-resolution data rolls in, and the overnight shift will assess latest guidance more thoroughly. In summary, wouldn`t be surprised to see a couple storms touch severe limits in the southeast CWA Saturday. MTF && .SHORT TERM... 308 PM CDT Through Saturday night... It has been a fairly benign weather day across the area as stratocumulus blankets northern Illinois and northwest Indiana amid large-scale subsidence behind last night`s storm system. These clouds should remain across the area through the night, though may become bit more broken as diurnal mixing ceases early this evening. The main focus is on expected periods of showers overnight into Saturday evening, with the potential for a few strong thunderstorms Saturday afternoon and evening across the southeastern CWA. Isolated to scattered showers may develop during the early morning hours Saturday within an axis of modest WAA under a weak mid-level wave lifting northeast across the mid-Mississippi River. The favored area is primarily north of I-80, especially in north- central Illinois, with a three or four hour window at any given location. Strengthening surface low pressure ahead of a intensifying mid- level wave will move across the central Great Plains and under the right- entrance region of an upper jet streak. Shower coverage is expected to increase across areas mainly around and northwest of I-55 by late morning with increasing low-level isentropic ascent and moisture transport. Marginal mid-level lapse rates over converge on the nose of strengthening low-level winds support the potential for a few embedded thunderstorms with this activity. Surface moisture will rapidly increase Saturday afternoon across central Illinois with the northward advance of a warm front ahead of the approaching low. As is usually the case in this region, the maximum northward extent of the warm front is not entirely clear, but indications are for the most-defined theta-e gradient to reach the I-55 corridor in central Illinois and possibly into the far southern Chicago metro by late afternoon. If at least some broken sunshine is realized south of the warm front, capping should be sufficiently removed to allow for thunderstorm development ahead of the approaching cold front. Resultant MLCAPE values possibly surpassing 500 J/kg amid significant effective shear of 60kt will support the potential for some stronger storms primarily around and southeast of I-55 during the late afternoon and early evening, with gusty winds and small hail possible. Showers and thunderstorm activity will end with the passage of the cold front for most locations by late Saturday evening. A few lingering showers are possible across northern Illinois with CAA overnight. Otherwise, NW winds will gust to 25mph or briefly higher by daybreak Sunday. Kluber && .LONG TERM... 212 PM CDT Sunday through Friday... In a sure sign of the change of seasons, next week will feature a roller coaster of temperatures and more breezy days than not. In the wake of a cold front, high temperatures Sunday will be cooler than the previous few, and in the lower 50s. Even with some sunshine, blustery northwesterly winds gust 25 to 35 mph will make it feel more like the 40s. The cooldown will be short-lived as an upper-level ridge builds into the Great Lakes and a quintessential spring-like southwest to northeast-oriented pressure gradient develops across the central United States. The net result will be highs climbing back into the 60s both Monday and Tuesday with breezy southwest winds. Since wind gusts are likely to exceed 30 mph and relative humidity values will likely drop into the 30-35% range (if not lower), concern is growing that any outdoor burning may lead to brush fires that spread readily, particularly on Monday. A strong cold front is then expected to swing through the Great Lakes Tuesday night or Wednesday ushering in another period of breezy northwest winds and falling temperatures. At this point, moisture appears limited ahead of the front which will probably prevent anything more than scattered showers. Considering the entire IQR of 850 mb temperatures from the ECMWF Ensemble drops below -10 C by daybreak Thursday, highs Wednesday and Thursday are poised to be much below normal and in the lower 40s (if not colder). On the bright side, the cold snap appears short-lived with a return to breezy southwest winds and warming temperatures appearing probable by next weekend. Borchardt && .AVIATION... For the 00Z TAFs... 659 PM...Forecast concerns include... Chance of isolated thunderstorms Saturday afternoon. Chance of showers overnight and Saturday. Mvfr cigs through the period. Gusty southeast winds Saturday morning. Mvfr cigs are slowly lifting across central IL early this evening along with some pockets of scattering. Maintained prevailing 2kft cigs through Saturday morning but only medium confidence and its possible cigs may lift to low vfr across some areas tonight. There may be some improvement, to vfr cigs Saturday morning but periodic mvfr cigs are possible. Low mvfr cigs or ifr cigs are possible later Saturday evening, ahead of a cold front that will move through either late Saturday evening or early Sunday morning. There will be periodic chances for showers including overnight through daybreak, with the best chances at rfd. Then again during the late morning/midday. Perhaps the best chance of heavier showers will be from early/mid Saturday afternoon through early Saturday evening. Its during this time period that isolated thunderstorms will be possible and mainly along/south of a arr/mdw/gyy line. Scattered thunderstorms are likely across central IL and central IN. Opted to keep thunder out of this forecast due to low confidence and expected low coverage. Light winds will become light southeast tonight and increase in speeds Saturday morning with gusts into the 20kt range by late morning. Winds will turn more south/southwest in the afternoon with gusts diminishing in the evening. Winds may remain more east/southeast at rfd and across northwest IL. A cold front will move through the area later Saturday evening, shifting winds to the west/northwest. Strong northwest winds are expected to develop early Sunday morning, after the current 30 hr ord/mdw tafs. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1004 PM EDT Fri Mar 26 2021 .SYNOPSIS... A weakening cold front will push through tonight. That front will then lift north as a warm front Sunday. A stronger front crosses the area Sunday night, followed by high pressure building over the area early next week. A strong cold front will move through late next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... As of 950 PM Friday...Rain chances tonight have primarily ended for the region. Latest obs and satellite imagery shows sea fog development near Hatteras Island and Ocracoke. Models are showing additional sea fog development overnight along the Crystal Coast as well, possibly lingering into Saturday morning. Sfc high pressure builds in early Sat AM and shifts light winds to the NE as a weak cold front pushes in from the north. Expecting southern locations to only cool off into the low 60s with low 50s in the northern OBX and NE counties. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... As of 350 PM Friday...The aforementioned cold front will move back north as a warm front Saturday, putting our entire area in the warm sector. Once again, somewhat decent shear parameters are possible, so if we are able to tap more sunshine and increase CAPE values, a chance of scattered showers and locally strong/svr storms are possible. The latest HRRR and 3km NAM show the timing of any showers/storms would be late in the day after 5 or 6 pm, so have kept PoPs mostly low for most of the day on Saturday. Another quite warm day with highs mid to upper 70s inland, and upper 60s to around 70 beaches. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... As of 345 AM Fri..Very warm temperatures on tap for the weekend, with a severe thunderstorm threat for Sunday. Much cooler and drier to start the work week. Then more unsettled weather expected Tuesday through early Thursday. Saturday Night through Sunday...Threat for some widely sct showers cont Sat night with weak isentropic ascent continuing, though have only 20-30% covg. QPF amts will be quite light. Main cold front then approaches and moves through the region later Sun, and ahead of the front, more showers/storms expected. Better convergence as far as models timing the front, bringing best chc of showers/storms early in the evening. Will therefore inc pops to 50-70% early evening when best sfc convergence occurs with main frontal bndry, then quickly shifting offshore by midnight and rapid drying commencing. Maintained the chc for some severe storms, as combination of instability and strong shear will be in place with this system. High Sun in the 70s coast to low 80s interior as low lvl thicknesses climb towards 1400M. Monday...Aforementioned strong cold front pushes through by the start of the work week, with a return to near climo or a bit below. Mo sunny skies and lowered TD`s, with blustery NW winds will make highs in the 60-65 range feel cooler. Low temps Mon night dip down to low 40s inland to 45-50 coast. Tuesday...Made big changes to the fcst Tue, as now appears a srn stream system will ride eastward through the deep south and spur cyclogenesis across the sern CONUS as region will be under RRQ of jet. Latest 26/00Z ECM/CMC on board with this soln, and have support from the earlier 12Z ECM ENS mean with higher probs for rain. Therefore felt confident to introduce 30-40% pops. Temps lowered a bit due to the clouds and showers, with 65-70 range. Wednesday through Thursday...Next large nrn stream shortwave trough and attendant cold front will approach by mid week, and thus unsettled conditions cont. Naturally timing issues abound this far out in time, and therefore will limit pops to 30-50% this period. May be another threat for thunder, as some instability is present with this strong front. Will introduce low end thunder probs to the fcst. Wed should be warm ahead of the front, with 70s for highs. Much cooler Thur with fropa and arctic air mass invading the East Coast. May be a late season freeze either Thu night or Fri night, as both ECM/GFS indicate H85 temps around -10C and thicknesses in the 525-530 dm range. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... Short Term /through Saturday/... As of 715 PM Fri...Clouds starting to break this evening, giving way to prevailing VFR conditions tonight. A weak cold front will drop through the region tonight and stall near or just south of our southern coast, turning light winds NE. Some sea fog development may occur and advect towards our southern TAF sites by early Sat morning, but confidence remains low on how far inland that will penetrate. Stalled front will begin to inch northward again after daybreak Sat and bring some cloud cover back into the area. Some MVFR/IFR ceilings are possible in the morning as this front moves north, turning light winds more SErly. As daytime heating gets going, hi res guidance has some showers and tstms firing up along the frontal boundary, which could provide a few moments of sub-VFR conditions in the aftn. Long Term /Saturday night through Wednesday/... As of 345 AM Fri...Sct showers, along with sub VFR cigs are expected Sat night, as low level winds will be northeasterly ahead of a warm front that passes through late. Return to VFR and gusty swrly winds Sun before strong cold front pushes through Sun evening. Better chc for showers/storms late Sun afternoon to early evening and tempo reductions to vsbys/cigs. && .MARINE... Short Term /Today and Tonight/... As of 4 PM Friday...Winds peaked somewhat earlier and have diminished a bit on many area waters. Based on the latest observations and trends, have lowered the SCA for the inland waters, with the exception of the Pamlico Sounds where some gusts to 25-30 knots are possible into the late evening. The SCA remains for the coastal waters, but seas should drop below 6 feet later tonight with wind subsiding behind a cold front that moves offshore. Still seeing some patches of sea fog from time to time, and this will likely cause vsby issues. Long Term /Saturday through Tuesday/... As of 345 AM Fri...Winds turn back around to the SW and inc once again during the day Sun, with SCA conditions once again expected ahead of strong cold front. Nwrly winds develop behind the front Sun night and will remain gusty before diminishing Mon. Winds turn back to the se or s on Tue with a low pres system moving up the East Coast. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...None. MARINE...Dense Fog Advisory until 2 AM EDT Saturday for AMZ152-154. Small Craft Advisory until 1 AM EDT Saturday for AMZ152-154- 156-158. && $$ SYNOPSIS...MHX NEAR TERM...CTC/ML SHORT TERM...CTC LONG TERM...TL AVIATION...TL/ML MARINE...CTC/TL CLIMATE...MHX
Area Forecast Discussion
National Weather Service Marquette MI
747 PM EDT Fri Mar 26 2021 .SHORT TERM...(This evening through Saturday) Issued at 413 PM EDT FRI MAR 26 2021 WV imagery and RAP analysis indicated a mid/upper level trough from central Canada into the western Plains. At the surface, a ridge extended from northern Quebec into western Lake Superior and northwest Wisconsin resulting in light northerly winds through Upper Michigan. Flow off of Lake Superior has maintained low clouds beneath a prominent 2000-3000 ft inversion. However, vis loop showed some signs of clearing over south central Upper Michigan. Tonight, even though slightly drier air will move in as low level winds become westerly helping to clear out the lower clouds from the west, mid/high clouds will start to increase overnight. This will keep temps from dropping off too far with min readings in the low to mid 20s. Saturday, Models were in better agreement with the lower onse of pcpn into Upper Michigan. Expect rain chances to gradually increase over the west and south in the afternoon while pcpn chances hold off til late over the northeast. 850-700 mb fgen associated with the advancing trough will support an area of rain moving into the west while WAA and 290k- 300k isentropic lift will support the rain edging northward from WI. WAA will also help push temps into the mid 40s and favor rain at the onset with snow chances holding off until late in the evening. .LONG TERM...(Saturday night through Friday) Issued at 405 PM EDT FRI MAR 26 2021 Precipitation associated with an approaching shortwave trough will spread across the CWA to begin the long-term period. Generally low impact weather is expected after snow comes to an end on Sunday, but temperatures are expected to ride the springtime rollercoaster next week. Precipitation should begin as rain around sunset on Saturday then transition to snow from west-to-east allowing for light snow accumulations by Sunday morning. The overwhelming majority of model guidance indicates total QPF around 1/3", but localized higher amounts are possible. Marginal air temperatures suggests highest elevations have the best chance of more than an inch of snow. Since the storm is strengthening as it moves through there`s potential for a more organized precipitation shield across the east where lower elevations may also pick up more than an inch. Precipitation will be ending Sunday morning as a cooler and drier air mass is advected into the CWA by gusty northwest winds. I have wind gusts approaching 30 mph across the east on Sunday, which may not be high enough considering deep mixing within the cold sector of a deepening cyclone. The 12z 12km NAM earned an honorable mention in this AFD by going completely off the rails with nearly 2" of QPF falling in about 12 hours near Harvey, MI. Tried to diagnose what the NAM was picking up on and concluded it effectively phased the shortwaves resulting in a rapidly deepening surface low and formation of a deformation zone. I scoured deterministic and stochastic model output and was unable to find any other guidance even half as impressive as the 12km NAM so it was disregarded for this forecast package. After a chilly start on Monday, a warm front is expected to lift across the area allowing temperatures to rapidly warm to near 60F across the west-central UP. Can`t completely rule out a rain shower with the warm front, but dry lower levels suggest a dry frontal passage. The temperature roller coaster continues on Tuesday as a cold front cuts across the CWA and ushers in a much colder air mass for Tuesday night into Thursday morning. Model guidance has trended colder with this air mass over the past 24 hours with 850 mb temperatures approaching -20C on Wednesday. This is cold enough for accumulating lake effect snow showers, but decided not to boost PoPs yet considering how dry the incoming air mass is expected to be. WAA will likely be underway by Friday allowing temperatures to rebound as we get into the first week of April. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 745 PM EDT FRI MAR 26 2021 With passage of sfc high pres ridge and loss of moist flow off of Lake Superior, expect low MVFR cigs (IFR at KCMX) to clear out during the night, beginning this evening at KIWD/KCMX and overnight at KSAW. Then, after a period of VFR conditions at all terminals into Sat aftn, approach of next disturbance will bring MVFR cigs back to all terminals during the mid to late aftn hrs. Rain should also develop at KIWD/KCMX by late aftn, and cigs should fall to IFR at KIWD late. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 413 PM EDT FRI MAR 26 2021 High pressure building over Lake Superior tonight will result in light winds. The next period of stronger winds will be on Saturday night into Sunday over the east half when gale force gusts will be possible with a batch of colder air. Freezing spray may also develop. The active weather period will continue from Monday into Wednesday night as wind gusts of 25-30 knots persist through that timeframe over the lake. Thursday looks to have wind gusts diminish to 20 knots or lower. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...EK AVIATION...Rolfson MARINE...JLB
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 332 PM CDT Fri Mar 26 2021 .Today into Tomorrow Morning: An arm of light rain is currently traversing eastern Nebraska from the southwest, and will continue northeast. So far only trace amounts have been observed with its passage. A recent surface analysis shows a weak surface low over western Kansas with a convergent zone extending eastward that has been somewhat enhanced by differential heating in north-central KS and south-central Nebraska. A look at water vapor imagery shows a shortwave impulse that will aid the western Kansas surface low in deepening somewhat. Surface heating/mixing could be sufficient for thunderstorm development along the surface convergent zone to the east of the triple point by this evening, where profiles would favor low-topped supercells. What is also possible is elevated convection this evening into early tonight across northeast KS in the warm advection zone (north of the surface front) on the nose of a developing low-level jet. CAMs indicate that initiation for these storms could occur late this afternoon into the early evening. This convection would then have to travel into southeastern Nebraska, and the best time for that look to be after 01z, and by that point those storms would be elevated with the primary hazard being some nickel to quarter-sized hail. Jet nosing along the KS/NE border looks to continue into the overnight hours and will extend chances for rain and some rumbles of thunder through around 4 AM for eastern Nebraska and western Iowa. .Saturday through Monday: After the low passes to the east of the area Saturday morning, northwesterly surface winds are expected to settle into place. Subsidence during the afternoon hours is expected to pick up and help scour out any residual cloud cover that will remain, leaving us some time to warm up. Highs Saturday are expected to reach the upper 50`s, with winds gusting to around 25 mph. Extended runs or the HRRR are trying to indicate some chances for precip Saturday evening, but seem to be on their own as other models indicating dry weather through the remainder of the weekend. Sunday and Monday will see the return of southerly winds and warmer temperatures to the area. While winds Sunday seem to be tame, the surface pressure gradient tightens up Monday to bring in gusty winds. The combination of strong surface winds, good surface heating, deep mixing are expected to raise fire weather concerns across the area. .Tuesday through Thursday: Models are in good agreement in the advance of troughing over the central CONUS by Tuesday, as a southern Canadian system drags a cold front across the region. What is uncertain at this time is how much precipitation will be associated with the frontal passage. Deterministic models indicate some precipitation in the area, but all solutions indicate a quick-moving front with only light rain. High temperatures are expected to take a dip Tuesday with the cold front, but that dip will be relatively short-lived as ridging builds in from the west and warming returns to close out the work week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 611 PM CDT Fri Mar 26 2021 Very light showers continue to move north through the area. Seemingly only light sprinkles and showers are reaching the ground. Will maintain VCSH at KOFK through 03Z Saturday. Cigs lower with the threat of convection later this evening... generally after 02Z Saturday. Generally IFR conditions are expected but may see some LIFR at KOFK and areas in northern Nebraska. Thunder is most likely at KLNK this evening. Breezy northwesterly winds develop around 00Z Sunday under drier conditions. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Petersen AVIATION...Nicolaisen
Area Forecast Discussion
National Weather Service Paducah KY
630 PM CDT Fri Mar 26 2021 .UPDATE... Issued at 626 PM CDT Fri Mar 26 2021 For aviation section only. && .SHORT TERM...(Tonight through Sunday night) Issued at 309 PM CDT Fri Mar 26 2021 Surface high pressure is providing dry conditions today as our strato-cu cloud deck gradually erodes from south to north. Attention late tonight into tomorrow morning will turn to the remnant boundary across the Gulf Coast states lifting back north. Warm air advection will fuel convective development across TN overnight into the morning. CAMs are in good agreement with keeping this activity south of our cwa. However, can`t completely rule out an isolated shower/storm working into our extreme southeast counties tomorrow morning through midday. A cold front will be moving through IL/MO tomorrow afternoon as shortwave energy pivots across the Midwest. The resultant southerly flow across our region will lead to an increase in moisture/instability. 12z HREF guidance indicates a plume of 1000- 1500 J/kg MUCAPE developing across SEMO, SW IL, and west KY. This combined with 0-6 km shear values increasing to 65-70 kts will support severe storms with any convection. However, the better forcing initially may remain tied to any remnant mesoscale boundaries from early day convection to our south and the frontal boundary to our northwest. This could leave our cwa in the in- between zone where storms have a hard time forming/moving in until after sunset (02-03z). There are some differences amongst the CAM guidance though. The ARW is faster with the front and brings in convection to our northwest by around 23z. The HRRR is more robust with developing convection northward from TN into at least west KY by 22-00z. Thus question marks remain, but the primary window of opportunity for severe storms appears to be anywhere from 22-05z. Convective activity is expected to quickly increase in coverage by mid-late evening and persist into the overnight before moving southeast out of the area. The highest potential for heavy rainfall amounts looks to be focused over west Kentucky, where some training could lead to some localized flooding issues. Portions of this area reside in a slight risk for excessive rainfall, while a moderate risk is in place to our south down in TN. Behind the system, a tight pressure gradient will be in place on Sunday resulting in breezy conditions. Northwest winds may end up gusting up around 25 to 30 mph. High pressure will move into the area Sunday night. The warmest day of the spring season so far looks to occur on Saturday, with temperatures soaring into the mid to upper 70s. A few 80 degree readings are possible. Much cooler readings return for Sunday, with highs only reaching the upper 50s to lower 60s. As the surface high moves overhead Sunday night, temperatures dip down into the 30s, and some scattered frost can`t be ruled out. .LONG TERM...(Monday through Friday) Issued at 309 PM CDT Fri Mar 26 2021 Dealing with a little unexpected variability in NBM initialization compared with Thursday`s model runs. The precipitation event forecast for Monday has essentially disappeared, but the midweek (mainly Wednesday) event was prolonged in duration by the NBM. There is low confidence in this solution at this time, so blended with other guidance, including the Canadian and European. The approach of the progressive northwest U.S. trough will likely be delayed up to 24 hours (was originally Monday) into the WFO PAH forecast area will occur late Tuesday, phasing in with marginal moisture Tuesday night into Wednesday morning. There may be some light shower activity across the Pennyrile region of west Kentucky toward daybreak Wednesday morning, but confidence is low. The trough axis will continue to be progressive through the upper atmosphere, moving through the WFO PAH forecast area Wednesday evening. Given the variability of moisture and timing of this system by various numerical model suites, am leaving the best chances for precipitation during the daytime hours on Wednesday, where the forecast signal has been most consistent the last couple of days. Also uncertain about thunderstorm coverage, but had to add a mention from a collaborative standpoint with surrounding offices. Ridging will dominate the remainder of the forecast period, keeping the area dry from Thursday onward. This will set the stage for lowered relative humidity values as well for this time period. Given the northwest flow Thursday into Friday, am a little concerned that there may be some frost development (if winds lighten enough), along with temperatures dropping close to the freezing mark. From an agricultural perspective, this may be of little impact, since most large scale vegetable/fruit crops are moving beyond the vulnerable stages of growth normally impacted by brief periods of frost/freezing temperatures. && .AVIATION... Issued at 626 PM CDT Fri Mar 26 2021 Generally clear skies expected through Sat AM, followed by increasing mid/high clouds ahead of the next storm system Saturday afternoon. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...GM SHORT TERM...SP LONG TERM...Smith AVIATION...GM
Area Forecast Discussion
National Weather Service Pocatello ID
131 PM MDT Fri Mar 26 2021 .SHORT TERM...Tonight through Sunday. A few residual rain/snow showers will dissipate this evening as high pressure builds into the area. Expect to see temperatures warm significantly over the weekend with highs in the 60s to near 70 possible across portions of the Snake Plain into the Magic Valley for Sunday. Dry weather is likely through the weekend with some patchy fog possible late at night and during the early morning hours. This will be mainly close to areas that have snowpack that is melting out. Winds will become breezy Sunday afternoon ahead of a strong cold front that will arrive for Monday. Some light rain/snow associated with the front is possible late Sunday night but snow accumulations look light as this is a fast-moving system. Snow levels ahead of the front will be over 7000 feet but will fall sharply with the front. 13 .LONG TERM...Monday through Friday. A vigorous cold front will tear through the Gem State on Monday. Deterministic models continue in good agreement on the timing of this fast-moving system. Snowfall accumulation will generally be light on account of the speed of the front. Some areas in the Central Mountains may get 3 to 5 inches of fresh snow. Surface winds could easily reach 35 to 40 mph in the Snake Plain. NBM continues to be on the low side of the wind, so have adjusted with a mix of the NBM 90th percentile and MEX guidance. Monday temperatures will be notably cooler in wake of the cold front. Monday`s high will be around 15 to 20 degrees colder than Sunday. Cool weather continues into Tuesday, but temperatures will warm through the rest of the week--possibly reaching 70 degrees in Pocatello by Friday! Hinsberger && .AVIATION...IFR stratus over PIH is slowly breaking up, and expect to be back up to VFR by mid-afternoon. Likewise, stratus at BYI will lift and break up around the same time. Guidance keeps things VFR through the rest of the TAF period, though the HRRR still wants to develop some afternoon showers over PIH and IDA this afternoon/early evening. Given the extent of the cloud cover, it would be difficult to destabilize enough for shower development. Hinsberger && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$