Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/15/23

in the forecast discussion today.

Once the cold front and upper low move through cooler air will be in place for later this week. In fact, with the growing season officially starting tomorrow (Monday, May 15th), those cooler temperatures will be something to monitor as we move later into the week. Based of the latest NBM, the probabilities for temperatures falling below freezing in western parts of the state are generally in the 15 to 25 percent range for Thursday night / Friday morning. && .AVIATION...(For the 00Z TAFS through 00Z Monday Evening) Issued at 626 PM CDT Sun May 14 2023 VFR conditions will prevail through the forecast period. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...JJS SHORT TERM...King LONG TERM...King AVIATION...JJS
Area Forecast Discussion
National Weather Service Columbia SC
809 PM EDT Sun May 14 2023 .SYNOPSIS... A series of disturbances will move over the region through the end of the week with more summer like weather pattern expected with daily afternoon showers and thunderstorms possible. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Lingering showers and isolated thunderstorms continue along a back door frontal boundary that currently stretches from the coastal plain up into the CSRA, with some additional activity near the mountains. Will expect the activity to continue to drift south and mostly dissipate later this evening, although latest HRRR indicates some of the shower activity to the north could possibly hold together and slip into our northern counties later tonight. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... Monday and Monday night: Appears as if guidance is trending towards a drier day across most of the forecast area through Monday night. Front will be across the southern counties, possibly even south of the cwa, to start off the day. At best, the southern Midlands and CSRA may see isolated showers from the morning into the afternoon, while drier air settles into the northern half of the area through the day. This drier air will try to push further southward into Monday night, but may stall out across the central Midlands. Most of Monday night will be dry, with best rain chances shifting more towards the upstate of SC. Temperatures will remain tricky, depending upon overall cloud cover and amount of drier/cooler air that can move into the northern counties. Still expect temperatures to be in the upper 70s to lower 80s. Tuesday and Tuesday night: The upper pattern will begin to flatten out somewhat, becoming more westerly through Tuesday night. This is in response to a digging upper trough that will be moving towards the region Tuesday night. As low-level winds turn more southerly again, moisture and the front south of the area will begin to return back towards the north through the day. There should be more coverage for showers and storms during the afternoon and evening hours, with a low severe threat. Temperatures bounce back once again into the mid to upper 80s for Tuesday afternoon, while the overnight hours will be mild as temperatures drop into the middle 60s. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Plenty of uncertainty in the longer term in regards to timing of upper shortwaves, and surface fronts, as they traverse through the area. For the most part, upper trough remains over the area through Thursday, then a deeper upper low moves Friday into the weekend. In general, will keep chances of rain in the forecast through much of this period, continuing with more diurnal activity. As for temperatures, kept mostly with NBM numbers through the period. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... VFR conditions for much of the period with restrictions possible during the early morning and sunrise hours. Weak frontal boundary continues to slide southward through the terminals with showers along the boundary. Overnight the boundary will continue slowly sliding southward with potential for some stratus and fog to develop. With rain occurring much earlier this afternoon at CAE/CUB much of the moisture has mixed out while at OGB/AGS/DNL higher amounts of rain later this afternoon and evening will create a different scenario. As such have included some MVFR cigs at AGS/DNL/OGB and will continue to monitor rain with lower cigs and vsbys likely with future issuances. Potential for restrictions too low to include for CAE/CUB as slightly drier air will be moving into the area overnight. Conditions will return to VFR by 14z with some potential for showers at AGS/DNL Monday afternoon however the potential is too low to include attm. EXTENDED AVIATION OUTLOOK...Scattered afternoon thunderstorms possible each day mainly during the afternoon and evening hours. With abundant low level moisture in place, fog and stratus possible during the early morning and sunrise hours each morning. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$
Area Forecast Discussion
National Weather Service Grand Junction CO
545 PM MDT Sun May 14 2023 .SHORT TERM...(Tonight through Monday night) Issued at 320 PM MDT Sun May 14 2023 GOES East water vapor imagery shows a pronounced mid-level low pressure spinning over northern Nevada this afternoon. To the east of this feature, southerly flow across eastern Utah and western Colorado is supplying a tap of sub-tropical moisture... characterized by precipitable water values roughly 100 to 200 percent of climatological normals. Meanwhile, partial sunshine has contributed to strong surface heating this afternoon. Combined with the moist air mass in place, 500 to 1000+ j/kg of surface based CAPE has developed which is a clear indicator of boundary layer destabilization. The CWA lies a little too far to the east of the low and the resulting wind shear for any meaningful severe convection, but very favorable low and mid-level lapse rates exceeding 8-9 C/km and at least a little flow aloft will make for an environment that is conducive to scattered pulse storms. These storms will be capable of producing brief moderate to heavy rain, gusty winds, and small hail. The HRRR and the NAMNEST have done a good job highlighting this potential so leaned on those pieces of guidance heavily with this package. As has been the case for the past several days, the higher terrain will have the highest odds of seeing the most robust shower and storm activity, though the adjacent valleys won`t be totally out of the clear either. After the sun sets and surface heating wanes, shower and storm activity will gradually diminish for most of the region overnight. The one exception may be across southwest Colorado and the San Juans where a trailing vort max passing through may keep showers going past midnight and into the pre-dawn hours. Despite the wave, large scale forcing will be weakening as the low over Nevada moves farther away. Thus, wouldn`t expect much more than light to moderate rain showers and occasional rumbles of thunder with this lingering activity. Strengthening high pressure over the southern Four Corners states and the diminishing influence of the low spinning far to our northwest will shift the prevailing flow from southerly to westerly and eventually northwesterly as the day progresses on Monday. This changing wind direction should cut off the flow of moisture into the forecast area, but with nothing to really flush out the moisture already in place yet, we`ll be dealing with another day of scattered afternoon showers and thunderstorms. Similar to before, convection will first fire along the higher terrain before drifting into the adjacent valleys later on. Once again, the main threats will be brief heavy rain, gusty winds, and small hail. Showers and storms will dissipate after sunset and give way to a quiet Monday night. Given clouds and precipitation around the next couple of days, temperatures will generally be near or just below seasonal averages during the day, and near to above seasonal averages at night. .LONG TERM...(Tuesday through Sunday) Issued at 320 PM MDT Sun May 14 2023 Shortwave energy will eject out of the previously retrograding low over the Pacific Northwest as it gets pinched by a Rex Block high over British Columbia and a ridge of high pressure trying to build in across the Four Corners. Meanwhile, a cut off low over the Baja will try to draw sub-tropical moisture northward through the Desert Southwest. This is a complicated setup but in terms of meaningful weather for our CWA, we will basically be stuck between these features on Tuesday and Wednesday with a zonal flow overhead. Drier air will try to work in from the north which will result in a reduction in precipitable water values with the best moisture residing near the Four Corners as residual moisture becomes trapped under this high. There looks to be a downturn in storm coverage Tuesday and Wednesday compared to previous days with best chances across the south, favoring the high terrain where the better moisture resides. Elsewhere, expect partly sunny skies and high temperatures about 5 to 10 degrees above normal. A more active period with more widespread coverage of storms looks to be in store Thursday through the coming weekend as a more robust trough drops in from the northwest, breaking that Rex Block high, and driving several shortwaves through the area from Thursday through the coming weekend. Regardless of more or less moisture and amount of forcing through this coming week, it looks to remain fairly unsettled with best chances of widespread storms late in the week. This warm up in temperatures in addition to potential for moderate to heavy rainfall with storms could lead to accelerated snow melt or at least an increase in flows on the rivers as indicated by some river forecasts. So, this will have to be monitored through the week. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 536 PM MDT Sun May 14 2023 VFR conditions will prevail for most areas the evening with VCSH or VCTS at many TAF sites this evening. Isolated to scattered showers and thunderstorms continue through about 03Z in the lower elevations and through about 06Z in the mountains with gusts to 35 kts, brief light to moderate rain with possible small hail and lower ceilings. Look for quiet weather overnight and scattered showers and thunderstorms to return again by about 18Z Monday. Coverage will be slightly less than today. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...MDM LONG TERM...MDA AVIATION...DB
Area Forecast Discussion
National Weather Service North Platte NE
632 PM CDT Sun May 14 2023 ...Updated Aviation Discussion... .SYNOPSIS... Issued at 204 PM CDT Sun May 14 2023 Key Messages: - Dreary conditions continue through Monday morning with mild temperatures expected. - Temperatures climb back into the at or above normal range by the middle of the week. - Isolated rain showers with a few rumbles of thunder are possible Tuesday afternoon/evening for areas primarily west of Highway 61. - A system will cross the area Wednesday bringing increased chances for scattered showers and thunderstorms to the area for Wednesday and Thursday. Recent GOES-16 WV and RAP 500-mb analysis showed a broad ridge of high pressure across the southeastern CONUS. Further northwest of this feature, an upper-level low pressure system was retrograding from northern Nevada into the PNW. Just south of this feature, an upper-level shortwave was apparent across the Baja Peninsula into portions of western Mexico. An upper-level ridge of high pressure has continued to hold strong across Alberta, encompassing much of the Canadian Provinces. Closer to home, a weakening low pressure system has stalled out across portions of the northern Plains into the Midwest. At the surface, associated low pressure was noted across far northwest Missouri with two stationary fronts accompanying it. One is extending southwest across the southern Plains while the other is extending northeast across the Mid- Mississippi Valley. Broad surface high pressure was noted across much of Canada, pushing south into portions of the northern Plains. A moisture plume surging north out of the Gulf of Mexico was evident and ample low-level moisture continuing on the backside of the weakening low pressure system. This has resulted in a dreary and breezy day with the entire area encompassed by low-level clouds with areas of light rain showers and drizzle developing across portions of the Sandhills into north central Nebraska. As of 2 PM CT, temperatures ranged from 50 degrees at Gordon to 57 degrees at Imperial. && .SHORT TERM...(This evening through Monday night) Issued at 204 PM CDT Sun May 14 2023 The aforementioned system currently impacting the region takes it`s time to exit resulting in persistent light rain showers/drizzle tonight into Monday morning. Deep layer moisture continues into Monday which is depicted by NAEFS and ENS ensemble guidance continuing to suggest that the mean PWAT will meet or exceed the 99th percentile across much of the area. These rain showers/drizzle will taper off through the late morning/early afternoon on Monday as the previously mentioned Canadian surface high pressure pushes further south into the High Plains. Total rainfall amounts will be much less than the area has seen the past few days of only a tenth of an inch to near three tenths of an inch. Subsidence behind the system will lead to gradually clearing skies Monday evening into Monday night. In regards to temperatures, overnight lows Sunday and Monday will be in the above normal range in the 40s and 50s. Mild daytime highs in the upper 50s to low 60s is forecast for Monday. .LONG TERM...(Tuesday through Sunday) Issued at 204 PM CDT Sun May 14 2023 Isolated rain showers with a few rumbles of thunder are possible Tuesday afternoon and evening for areas primarily west of Highway 61. Meager MLCAPE values nearing 500 J/kg and mid-level lapse rates approaching 7 C/km will likely result in rumbles of thunder across the area. The severe potential remains low given the lack of forcing for ascent with minimal rainfall amounts anticipated of a trace to maybe a few hundreths of an inch. Warm temperatures return for a brief period on Tuesday and Wednesday with highs climbing into the upper 70s to low 80s across the region. These temperatures are 5 to 10 degrees above the climatological normal for the middle of May. The main focus in the long term period surrounds the potential for scattered showers and thunderstorms impacting the region Wednesday into Thursday as a northern stream trough tracks southeast into the far northern Plains. Model solutions continue to suggest isolated severe thunderstorms possible across the Panhandle into portions of the western Sandhills Wednesday afternoon and evening. Long range model solutions continue to signal an increase in instability and shear across those areas, however, weak flow aloft may limit the potential for any organized storm. As the low advances across the Upper Midwest, an accompanying cold front will track south across the region resulting in increased frontogenetical forcing along and behind the FROPA. This will result in increased precipitation chances again during the day on Thursday. However, meager instability should limit any severe potential for Thursday, though rumbles of thunder cannot be ruled out. Given that this is in the Day 4 and Day 5 range, cannot hone in on exact details, however, this will be the time period to keep an eye on in the coming days. Beyond Thursday, the Canadian cold front will sweep across the area with surface high pressure building in behind it. Somewhat "cooler" temperatures are anticipated on Friday before climbing back into the well-above normal range into the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 631 PM CDT Sun May 14 2023 Few showers located across northern zones heading southwestward with most areas seeing a VSBY restriction in the SHRA of 3-5SM along with MVFR to IFR CIGS. Would expect the showers to drift south through the evening and although won`t amount to much precip, will reduce VSBYs somewhat and trend toward IFR to LIFR conditions as the showers end and areas of fog develop. Would expect any fog to develop first over the north central areas and have introduced lower VSBY with this TAF cycle at KVTN, then KLBF toward daybreak. Have used the NBM VSBYs as it best aligns with somewhere between the 10th and 25th percentiles of HREF VSBYs which seemed to handle the idea best. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...Viken SHORT TERM...Viken LONG TERM...Viken AVIATION...Stoppkotte
Area Forecast Discussion
National Weather Service Louisville KY
944 PM EDT Sun May 14 2023 .Forecast Update... Issued at 944 PM EDT Sun May 14 2023 A broad surface boundary stretches roughly from Owensboro to Tompkinsville this evening, and will drift slowly southwestward to around an Evansville-Bowling Green line by morning. The best convective chances overnight will be west of this boundary in an air mass of greater moisture and instability. The vigorous convection from southern Illinois into western Kentucky this evening will slide to the southeast, but has already shown signs over the past hour of becoming less organized and weaker. The convection should continue to weaken as instability wanes overnight, but we still may see some showers and a few thunderstorms tonight west of I-65. The most likely region to see a stronger storm is west of the Natcher Parkway. && .Short Term...(This evening through Monday) Issued at 222 PM EDT Sun May 14 2023 Current (18z) surface analysis reveals a weak NW to SE oriented frontal boundary across the region. While the temperature gradient near the frontal boundary is fairly weak, there is about a 10 degree F dewpoint spread between our southwest CWA (low 70s dewpoints) to the northeast CWA (low 60s dewpoints). It is slowly but steadily advancing southwestward. The boundary has become fairly evident on satellite imagery over the last few hours, as a strato-cu field has developed generally within the warm sector of the boundary in the higher low-level Td air. The higher dewpoints have also aided in destabilization of the atmosphere, and while little to no CIN exists within the warm sector, the convergence along the frontal boundary appears to be too weak to help initiate any convection at this time as visible satellite imagery shows a `flat` cumulus field. Areas north and east of the boundary ("cool" side) should stay dry through the remainder of the day. Conversely, most folks will likely stay dry on the other side (warm sector) within the region, though we could see very localized showers or storms initiate near or on the boundary late this afternoon into the early evening hours. Some of the latest HRRR runs suggest this, mainly toward the vicinity of the BWG area points westward. A more organized convective threat will develop out west (Missouri, Illinois), and eventually dive southeast into Kentucky, but it may not be until well after sunset that we`d have any shot of seeing showers/storms in our neck of the woods. Current forecast highlights the "best" (~20%) chance for showers/storms mainly west of I-65 and south of I-64 overnight into early tomorrow morning. A couple of the storms could be strong, possibly marginally severe, if they arrive in our CWA, though the overall severe threat would be very low. Gusty winds and small hail would be the main threats with any stronger storm. Light showers may move in from the north a little before dawn Monday and could persist through the morning and afternoon hours, though overall coverage should be isolated to scattered at best. Additional storm development is possible near the TN border where some lingering instability could fuel a few storms. Highs Monday will be a tad cooler in the post-frontal airmass with clouds, ranging from low 70s in southern IN to low 80s in southern KY. .Long Term...(Monday night through Sunday) Issued at 320 PM EDT Sun May 14 2023 --------------------------------------------------------------------- Key Messages... - Increasing chance for showers and thunderstorms on Tuesday; an isolated strong-to-severe storm cannot be ruled out across south central KY. Locally heavy rainfall and isolated flooding is also possible. - Drier weather returns Wednesday into Thursday with seasonable highs and cool morning lows. --------------------------------------------------------------------- Monday Night - Tuesday Night... At the beginning of the extended forecast period Monday night, ridging aloft over the southeastern U.S. will begin to recede as a mid- and upper-level shortwave slides across the top of the retreating ridge. At the surface, an open wave sfc low will slide from west to east across the Ohio Valley, with latest guidance shifting this track farther north along the I-64 corridor. South of the sfc low track, low-level warm and moist advection will promote increased instability, with latest guidance depicting a swath of upper 60s and lower 70s dewpoints Tuesday afternoon across south central Kentucky. While ensemble mean CAPE values remain limited, 14/12Z NAM and GFS deterministic runs paint a swath of 1500+ J/kg SBCAPE along and south of the Parkways during the day on Tuesday. As a result, there is growing concern for strong to potentially severe storms in these areas which are able to destabilize on Tuesday. Additionally, stronger flow aloft is resulting in 30-35 kt effective bulk shear, which will enhance the ability of convection to become organized. Wind profiles look fairly unidirectional in the low- levels, with modest low-level SRH, while low (7-7.5 C/km) and mid- level (6-6.5 C/km) lapse rates are marginal to slightly favorable. Taking all of this into consideration, would not be surprised if the severe threat is increased across south central KY in upcoming SPC outlooks, with damaging winds and severe hail being the main threats. Outside of the severe potential, heavy rainfall and flash flooding threats will also have to be monitored, with PW values approaching 90th-95th percentile. With stronger flow aloft, storm motions aren`t too concerning; however, if heavier cells train over the same areas, isolated swaths of 2-3 inches of rainfall and localized flash flooding would be possible. Along and north of the sfc low track, which at this time would appear to be north central KY and southern IN, rain is still likely on Tuesday, with cooler air near the sfc limiting instability and thunderstorm potential. Widespread precipitation totals of 0.25+" would be favored, though this could yet change based on later trends in guidance. The sfc low is expected to clear the region early Wednesday morning, with drier air moving through in its wake. Wednesday and beyond... By Wednesday morning, the shortwave aloft will have cleared the area, with high pressure across the Great Lakes attempting to work southward during the day on Wednesday. Some medium-range guidance tries to develop isolated precipitation along the edge of the sfc high Wednesday afternoon across western KY; however, will advertise silent PoPs for now given the expected dry air mass. By Thursday, another mid- and upper-level disturbance will begin to descend southeastward from central Canada into the upper Midwest. While direct impacts from this disturbance shouldn`t arrive until Friday, weak low-level return flow may be just sufficient for a low-end chance of afternoon showers/storms across portions of southern KY. As this return flow strengthens on Friday into Friday evening, increasing moisture will promote enhanced precipitation chances area- wide, with showers and thunderstorms developing ahead of an approaching sfc cold front. At this time, the front is progged to move through late Friday night into Saturday morning, with another shot of cooler and drier air arriving in its wake for the second half of next weekend. However, forecast confidence at this range remains limited, to stay tuned as further guidance comes in later this week. && .Aviation...(00Z TAF Issuance) Issued at 725 PM EDT Sun May 14 2023 Widespread convection developed this afternoon from the western Gulf of Mexico to the lower Missouri Valley to the Southeast in a ring of fire around the periphery of an upper high over the lower Mississippi Valley. Storms in Missouri and southern Illinois are expected to drift to the east and southeast tonight, weakening as we get deeper into the night. Will account for this with some VCSH at our western TAF sites, HNB and BWG, after midnight. With humid air in the Bowling Green region, along with very little wind, some MVFR BR may form at BWG around sunrise. On Monday instability will develop in the afternoon south of an east- west boundary, leading to the possibility of some scattered showers or thunderstorms in the BWG area. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...13 Short Term...DM Long Term...CSG Aviation...13
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
848 PM CDT Sun May 14 2023 .UPDATE... Issued at 848 PM CDT Sun May 14 2023 Only minor adjustments made to going forecast this evening, mainly to add hourly detail to pop grids as showers decrease in coverage, as well as to remove thunder mention from our far southern counties. Weakening surface low pressure was analyzed near Kansas City this evening, with a sharp quasi-stationary front extending southeast through southern IL and western KY. Farther north, an elongated area of seasonably strong high pressure stretched from the northern Plains through the northern Great Lakes region. Within the gradient region across northern IL/northwest IN, somewhat blustery northeast winds continued to bring cooler air into the area with temperatures currently in the low-mid 50s across much of the forecast area. Light rain/showers have persisted area since this afternoon, driven largely by frontogenetic forcing (most notably in the 700-500 mb layer) within the elevated baroclinic zone north of the stationary front along with some aid from upper level divergence in the right rear entrance region to an upper level jet streak to our east. High- res model guidance depicts both of these forcing mechanisms weakening tonight as the upper jet streak peels off to the east- southeast, and the elevated baroclinic zone weakens as the surface front sags south. The result will be a continued decrease in shower coverage through late evening, especially across the northern half of the forecast area. Farther south, some lingering f-gen forcing in the 925-850 mb layer may allow for some isolated showers to persist at times into the overnight hours mainly south of the I-80 corridor. With these trends already evident in regional radar imagery, have made some tweaks to pops across the area to depict gradually decreasing coverage of showers across the north, and maintained low pops (20 percent) overnight in the south. RAP mesoanalysis and forecast soundings indicate all convective instability has shifted south of the forecast area into central IL, and thus removed any lingering mention of thunder along our LOT/ILX border. Updated digital/text forecast products available. Ratzer && .SHORT TERM... Issued at 235 PM CDT Sun May 14 2023 Through Monday... A broad region of showers is ongoing early this afternoon in areas generally northwest of I-55. This will continue to slowly drift southeast the rest of the afternoon. So far it has struggled to make inroads over the city thanks to much drier low levels indicated by O`Hare and Midway dewpoints near 40F. At times, cloud tops have grown tall enough to see an few lightning strikes embedded in the showers, though so far this has been limited to locales along and west of I-39. Think the potential for lightning the rest of the afternoon into early evening will be limited to areas in Illinois along and south of a Mendota to Kankakee line. Hi-res guidance begins to thin out the area of showers into a narrower band with isolated showers that persists through the overnight hours. Exactly where this band ends up remains somewhat in question so it felt prudent to carry a mention for isolated showers for most areas overnight. Think in general these showers will be on a diminishing trend toward daybreak, though cannot rule out a few light showers/sprinkles through the day mainly south of I-80. Depending on how long these light showers continue and greater cloud coverage it could slow our warming on Monday. Left the temperature forecast mostly unchanged with upper 60s to lower 70s. Northeast winds and an afternoon lake breeze will keep temperatures near the shore in the upper 50s to lower 60s. Taking a broader look at the region, showers are ongoing across Oklahoma and Kansas on the western side of the upper ridge. Model guidance suggests this activity will continue to lift and ultimately round the ridge into central Illinois. The northern edge of these showers may sneak into areas south of I-80 late Monday night. More details about shower chances Monday night into Tuesday are provided in the Long Term Discussion below. Petr && .LONG TERM... Issued at 235 PM CDT Sun May 14 2023 Tuesday through Sunday... Over the next few days, the persistent upper-level anticyclone centered over the southeastern United States will begin to break down as substantial upper-level troughing develops over the northeastern United States. As mid-level anticyclonic steering flow decays, it will lift a diabatic generated low pressure system currently in central Texas roughly toward Joplin, MO to Springfield, IL, and eventually Lexington, KY by Tuesday night. Along and north of the path of the low, a narrow shield of rain is poised to develop along the remnant baroclinic zone draped across the middle Mississippi River Valley. At this point, it appears the rain shield may lift as far north as a line from Pontiac to Rensselaer, though confidence is lower than average owing to the convective origin of the low (e.g. model guidance may not by fully resolving the structure of the low). At any rate, chances for rain appear to be increasing across central Illinois Tuesday morning. Meanwhile, confidence continues to increase in the passage of a Lake Michigan pneumonia front Tuesday afternoon across northeastern Illinois. Pattern recognition suggests temperatures may drop some 15 to 20 degrees in the span of an hour or two particularly close to the Lake Michigan shoreline! Steep low-level lapse rates ahead of the front may support a few showers, particularly near the Wisconsin state line. However, the most notable impact of the front will be the plummeting temperatures. After sunset, a surface high will quickly build into the Great Lakes leading to clearing skies and slackening winds. Lows Tuesday night may approach the 40 degree mark close to the Wisconsin State line. With the surface high parked overhead Wednesday and Thursday, generally quiet conditions will prevail with gradually warming temperatures, light winds, and plenty of sun. The next chance of rain will arrive Friday as an upper-level wave and associated cold front move across the Great Lakes. With limited moisture return ahead of the wave, ensemble model guidance advertises only a a 50- 60% chance that 12-hour rainfall amounts exceed 0.1" of an inch...So any rain that occurs won`t be soaking. Ensemble meteograms provide signals for dry and seasonable weather from May 21-25 with a trend toward warmer temperatures and perhaps chances for thunderstorms thereafter. Borchardt && .AVIATION... For the 00Z TAFs... 629 PM...Primary forecast concern is rain end time this evening. Light rain will continue through mid evening, as it slowly dissipates and shifts southeast of the terminals. Still some uncertainty for an exact end time and have maintained previous timing, 03z for the Chicago terminals. There may still be some sprinkles or isolated showers after this time. Northeast winds will continue through early Monday evening. Some gusts to 20kts are possible early this evening then speeds are expected to diminish under 10kts overnight, increasing back toward 10 kts on Monday. Winds are expected to shift light westerly Monday evening. 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 Marquette MI
1202 AM EDT Mon May 15 2023 .SHORT TERM...(This evening through Monday) Issued at 330 PM EDT SUN MAY 14 2023 Water vapor imagery and RAP analysis show a strong mid-level anticyclone centered over Alberta. Downstream of this mid-level ridge a shortwave is dropping slowly south through Upper Mi this afternoon, but given how very dry the air mass is over the area no pcpn is associated with this wave, only high cloudiness. This high cloud cover will push south of the area this evening with the shortwave and high pressure will dominant all levels tonight. With diurnal mixing through this very dry airmass this afternoon dew points have dropped into the teens to lower 20s across much of the interior. These dew points combined with high temp readings mostly in the 60s have resulted in min RH percent values in the teens to lower 20s. Fortunately, NE-E winds have stayed in check for the most part with gusts generally staying blo 15 mph. The very dry conditions and low RHs will warrant keeping the ongoing SPS for elevated fire danger in effect through early evening. Given the very dry airmass in place and the sfc high pressure moving over the area this evening into the early overnight, ideal radiational cooling conditions could yield min temps on the lower end of guidance. It`s a good bet temps could dip blo freezing later tonight across a good portion of the interior west where patchy frost will be possible, so anyone with sensitive potted plants may want to cover them or bring them inside tonight. .LONG TERM...(Monday night through Sunday) Issued at 252 PM EDT SUN MAY 14 2023 Key Messages: -Warm and dry Monday -A dry cold front Tuesday brings more normal temps, cool overnight -Quiet Wednesday before light rain Thursday/Friday -Ridging Saturday, keeping an eye on a trough nearby Sunday The long term forecast starts with a 1032 mb high pressure stretched broadly across the Upper Midwest coinciding with 500 mb height anomalies of +28 dam. NAEFS geopotential height and SLP are all in the 99th percentile to maximum of climatology for 12Z Monday. This dry air and subsidence should keep precip (and clouds, for that matter) out of the forecast, especially with NAEFS PWAT in the bottom 10 percent of climatology. The big forecast focus for Monday will be on the fire weather conditions as mixing the boundary layer from the CMC model output gives surface dew points in the 20s and teens only recovering to the 30s while the prime radiation heating leads to highs in the 70s and high 60s. The wind forecast begins with light westerlies, but throughout the morning, winds increase to 10-15 mph with gusts up to 20 mph as the pressure gradient increases between the high over the Midwest and Northern Plains and a deepening low over the Canadian Maritimes. While the winds alone are not critical, the minRH`s in the 20`s% range and lower in some areas along with highs around 70 lead to borderline critical fire weather conditions. Tuesday, the surface high weakens and sags south as 500mb anomaly erodes back towards 0. A shortwave trough is expected to pass north to south through the region midday Tuesday, though it will quickly be replaced by a high pressure in its wake for Wednesday. No precip is expected with the cold front passage as even the NBM 95th percentile has no measurable precip in the forecast area. The cold fropa will bring Tuesdays high temperatures down 10+ degrees from Monday`s highs, bringing highs back in line with the climatological averages. Additionally, with the cold fropa and expected clear skies for radiational cooling, lows Tuesday night could reach sub-freezing in some interior locations. A quiet Wednesday is expected as ridging will dominate the forecast before the next 500mb trough digs southeast through Ontario and the Upper Great Lakes vicinity Thursday. The 12Z GEFS has much higher certainty than this time yesterday that the low center will be around 1000-1005mb passing along the northern shores of Lake Superior. However, the range of QPF solutions has increased, with the 25th percentile being around 0.05-0.2 inches and the 75th percentile being half to 3/4 of an inch of rain. Despite the increasing trend in QPF, impacts are still expected to be fairly low as thunder coverage is only expected to be isolated at most in the interior west and with rivers receding after the most recent snowmelt, hydro concerns are not particularly high. The NBM does have a 5 percent chance of snow for the highlands of Baraga and Marquette counties with lingering precip Friday, but temperatures should be far too high for that solution. A brief ridge will take hold of the region Saturday, though Sunday`s weather will be hard to pin down as the next feature of note is a trough over the Hudson Bay on the 12Z GFS. Some ensemble members bring the trough far enough south to bring precip to the region, but model spread (and thus, uncertainty) is high at this forecast time. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 1202 AM EDT MON MAY 15 2023 A dry airmass and surface high pressure continue to result in VFR conditions for the duration of TAF period. Winds will become primarily southwesterly around mid morning at all TAF sites, and strong at CMX this afternoon with sustained speeds of 12 to 15 kts and gusts to 24 kts. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 252 PM EDT SUN MAY 14 2023 Winds are below 20 kt through Monday afternoon, when a cold front from the north brings southwest winds up to 30 kt. A gale force gust or two cannot be ruled out Monday evening, especially in the central portions of the lake near the Keweenaw Peninsula. Winds shift to the north Tuesday evening and gusts remain around 20 kt through Tuesday evening. A brief high pressure will help bring winds below 20 kt Wednesday before an approaching low pressure will bring southerly gusts of 20 to 25 kt overnight into Thursday, becoming westerly from west to east throughout the evening. Friday, winds become northerly, still remaining around 20 to 25 kt. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...GS AVIATION...TDUD MARINE...GS