Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/11/20

Area Forecast Discussion
National Weather Service Denver/Boulder CO
817 PM MDT Sun May 10 2020 .UPDATE... Issued at 816 PM MDT Sun May 10 2020 Not much to change at this point. Any shower activity over the higher terrain will likely hold off until around sunrise. Across the plains there is a well developed Denver Cyclone southeast of DIA. Lower level clouds have been increasing across nrn areas of the plains so will increase cloud cover overnight. && .SHORT TERM...(This evening through Monday) Issued at 250 PM MDT Sun May 10 2020 Colorado remains under a moderate Northwest flow pattern this afternoon with weak ridge aloft over the eastern Great Basin. Already seeing some increase in high level moisture streaming downstream from the ridge. There is a weak system moving into the western Great Basin and desert southwest with some moisture and instability with quite a bit of thunderstorm activity over Arizona and some sneaking into southwest Colorado. Could see a late day shower over southern portions of our mountains but still moisture and instability are marginal at best. The better moisture and instability will move into the mountains later tonight with some weak QG ascent and will have the higher pops then with even a few thunderstorms possible in advance of weak trof. Across the plains, southeast low level flow will develop with some possible stratus later tonight over the far plains and some increase in low level moisture. Surface dewpoints expected to rise back into the 40 by later in the day on Monday. Given higher cloud cover on Monday, temperatures will be cooler and instability limited for much of the day with very little in the way of surface based CAPE, except from 500-1200j/kg over the Palmer Divide if you believe the RAP/NAM higher CAPE solutions. Suspect that is somewhat overdone as RAP showing dewpoints close to 50 (highly doubtful). Best chance for stronger thunderstorms or low end severe may be over the mountains where the best instability will reside with CAPE values of 500-1000j/kg. PW values also expected to range from 1/2 to 3/4 of an inch by Monday afternoon. Will have basically chance pops over the plains during the afternoon. .LONG TERM...(Monday night through Sunday) Issued at 250 PM MDT Sun May 10 2020 The long term will be dominated by several shortwave troughs rounding a semi-permanent and nearly stationary upper low near Hudson Bay. Widespread showers across the forecast area and isolated thunderstorms near the higher terrain will be ongoing early Monday evening. Activity will be waning from west to east through the night, however QG motion will remain slightly upward and southeasterly surface winds into the plains will keep PW values elevated to near the 90th percentile. Low clouds and patchy fog will likely spread west over the eastern plains, possibly as far as into the urban corridor. On Tuesday, flow aloft will transition to a drier and warmer west- southwesterly direction, with increasing wind speed as another shortwave trough crosses the Northern Rockies. The mountains will experience these increased speeds, for a breezy day. At the surface, a surface high over the Great Plains will keep in breezy southeasterly moist winds over the eastern CO plains, however a surface trough will be forming along the foothills and possibly into the urban corridor. Models disagree on this position, but a dry line will form at the meeting of the two airmasses, and may be able to fire off some showers and storms Tuesday afternoon. GFS has the trough further east, keeping the chance of storms further east with more stable conditions across the urban corridor. NAM has it further west, giving more of a chance of storms starting at the urban corridor, with more instability, however it keeps it capped as the cooler lower airmass in easterly flow. Will have a slight chance of storms mainly over the Cheyenne and Palmer Ridges where they would get out of the lower stable airmass, then have a higher chance out east in the evening. Warmer temperatures and drier air will push in Wednesday in west- southwesterly flow. This may increase fire weather concerns over South Park, but fuels are likely close to green up, decreasing the concern. Another shortwave crossing over the Great Basin will move across northern Colorado, but not likely until later. So will have just a slightly chance of showers and storms mainly north of I76 during the afternoon, with chances increasing across most of the forecast area in the evening as a cold front pushes south, keeping chances of showers through midnight. Thursday will be a few degrees cooler and another day of scattered to numerous showers and thunderstorms as yet another shortwave from the Great Basin crosses the state - late again so that showers will likely last overnight and even into Friday morning. Residual moisture in the area and another shortwave trough moving across the Northern Rockies will keep showers in the forecast through Friday. Models are diverging on the strength of this trough and how deep it digs south. Will keep a chance of showers and thunder through Saturday evening for this. After this, models show a ridge moving into the area for a warmer and drier Sunday in southwest flow. The ridge is being pushed east by a deepening large system off the Pacific Coast, slated to move slowly into the Great Basin by Wednesday, which will bring much warmer temperatures for the beginning of next week in south-southwest flow. Both the EC and GFS are showing 700 mb temperatures of 14-16 degrees C by Tuesday, which would translate into highs in the upper 80s for the plains, in the 60s for much of the mountains. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 816 PM MDT Sun May 10 2020 Denver Cyclone was southeast of DIA as winds have maintained a more NNE direction early this evening. Models have a poor handle on the location of this low. If this low stays nearly stationary winds at DIA may maintain a more northeast component overnight. Also there is a lower level cloud deck down to 7000 ft which has developed along and north of a Fort Collins to Fort Morgan line. Some of these clouds could affect the airport by midnight if the low level flow remains more northeast. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...RPK SHORT TERM...Entrekin LONG TERM...Kriederman AVIATION...RPK
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1153 PM EDT Sun May 10 2020 .AVIATION... Lower tropospheric cold air advection acted upon a slow to move low- mid deformation to allow for snow to mix in at all of the Metro Detroit taf sites. Latest model data has this ending by or shortly after 06Z. Low level cold advection supports MVFR stratus development. Model soundings suggest some potential for trapped moisture to mix out late tonight, but pattern recognition suggests MVFR cigs persisting through the morning. VFR ceilings late morning into the afternoon. Northwest winds are expected Monday afternoon in the 15 to 25 knot range. For DTW...Low level cold advection will support saturation and MVFR cloud through Monday morning. VFR cigs Monday afternoon. DTW THRESHOLD PROBABILITIES... * High for ceilings at or below 5000 ft tonight && .PREV DISCUSSION... Issued at 1045 PM EDT Sun May 10 2020 UPDATE... Precipitation type has changed over completely to snow in the highlands here of northern Oakland County this evening. Combination of steady near surface cooling T 33/Td 32 and wet bulbing with persistent moderate precipitation rates has allowed for all snow at the office with bright banding lighting up the radar. Gauging the progression of precipitation within the stretching deformation axis/occlusion or lack thereof, steady southward progression of the cold air the remainder of the evening will allow most locations to witness snowflakes before precipitation ends. A very quick snowfall accumulation has been observed in grassy areas/on elevated surfaces here at the office due to a period of large sticky aggregates. With warm ground temperatures not expecting much issues on roadways across area, but an opportunity certainly exists to witness a measurable snow accumulation here on May 10th. The pivot of the band is largely on schedule with latest HRRR runs, expect this precipitation to hang around the area through 06Z before quickly waning. PREV DISCUSSION... Issued at 359 PM EDT Sun May 10 2020 DISCUSSION... The center of the surface low will shortly drift just east of Detroit forcing the cold front east and south of the area. This will bring an end to the convective portion of the system as now the active deformation axis becomes positioned over SE MI. The upper level circulation will catch up to the surface reflection while the deformation band sets up over northern portions of the CWA which will add mid level support to this pre-existing forcing. Models show a flare up of 700-850mb fgen right overhead after 00Z which then lasts several hours into the night while pivoting over the area on its eventual track eastward. This will keep showers likely through about midnight before the entire system gets far enough east to no longer be a factor locally. Even as winds become northwesterly and introduce cold air advection to the back of the system, shallow moisture depths mainly between 0C (900mb) and -10C (775mb) will minimize chances to change over to a frozen ptype although can`t rule out a few wet snowflakes mixing in. By Monday morning, northerly flow cold advection pattern will bring a return of 850mb temps down around -7C. This will result in steep low level lapse rates as surface temps rise into the mid/upper 40s. There will be enough residual moisture to produce a healthy deck of clouds and possibly even a period of flurries as a sheared axis of vorticity draped north of the Great Lakes gets pulled down through lower MI. Broad area of high pressure across the Plains will then slide south and east across the Great Lakes by Monday evening. Winds will weaken though remain primarily northerly, and a much drier airmass will fill in across the state. The cold resident airmass, clear skies and light winds will once again allow min temps to drop into the upper 20s Monday night into Tuesday morning. A freeze warning will likely be needed for at least a portion of SE MI. High pressure will then center itself over the region on Tuesday while upper level ridge begins to slide east into the Plains. Longwave pattern overall will deamplify as the strongest portion of the jet races off the east coast. The more westerly flow overhead will begin to moderate the airmass as warm advection sets in. Combined with a good deal of sun and high sun angle, we should see a nice jump in high temps into the mid 50s. The ridge axis will slide through the region Wednesday bringing increasingly warmer air into the region as we fall solidly into the southwest flow regime. This will also mark the start of a potentially active stretch of weather with GFS and EURO both hinting at a series of shortwaves lifting through the region in the Thursday to Saturday timeframe. MARINE... Strong winds return this evening as a low pressure system advances eastward. A warm front currently bisecting lower Michigan will keep winds W/SW on the warm (south) side and NE winds on the cold (north) side early tonight. Additionally, a cold front associated with the low will force gusty showers through the southern lakes prior to midnight. Gusts to 35 knots will be possible at times. A broad NW wind shift will occur behind the low overnight with a potent surface pressure gradient keeping winds elevated overnight. Small Craft Advisories are already in effect with expected gusts in the 20-25 knot range as 925 mb height falls phase with increasing LLJ winds. Will need to monitor forecast trends to see if Lake St Clair and Lake Erie need to be added for the 10 pm marine update. Dry advection makes for a rain-free start to Monday before scattered showers develop during the afternoon. Diffuse high pressure arises on Tuesday with quiet weather preceding a stronger ridge arriving on Wednesday which will initiate a warming trend through the end of the week. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...Lakeshore Flood Advisory until 4 PM EDT Monday for MIZ049-055-063. Lake Huron...Small Craft Advisory until 4 PM EDT Monday for LHZ421-441>443. Lake St Clair...Small Craft Advisory until 4 PM EDT Monday for LCZ460. Michigan waters of Lake Erie...Small Craft Advisory until 4 PM EDT Monday for LEZ444. && $$ AVIATION.....CB UPDATE.......CB DISCUSSION...DRK MARINE.......KK You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service Green Bay WI
603 PM CDT Sun May 10 2020 Updated aviation portion for 00Z TAF issuance .SHORT TERM...Tonight and Monday Issued at 238 PM CDT Sun May 10 2020 The latest RAP analysis and satellite/radar imagery show low pressure moving across southern Lower Michigan early this afternoon. Behind the low, ample cloud cover and chilly temps prevail across northeast Wisconsin, with readings ranging from the middle 30s to the middle 40s. Plenty of cloud cover exists upstream over and north of Lake Superior, so do not expect much clearing this afternoon. Light precip, however, is diminishing from north to south, but still some light rain or drizzle appearing from Kewaunee to Stevens Point. With a cool airmass in place and potential for clearing skies tonight, forecast concerns mainly revolve around the potential for freezing temperatures. Tonight...As low pressure pulls away, high pressure positioned over the Plains will edge ever so slightly towards the western Great Lakes. North winds will therefore continue, and will likely persist at most locations to prevent decoupling. Cloud cover will also be an issue, as models indicate that a push of drier air will not occur until very late tonight. Will side with guidance slightly warmer than the NationalBlend, which will place lows ranging from the middle 20s to lower 30s. Forecast lows remain below freezing at most locations, so will issue a freeze warning for central to northeast Wisconsin where the growing season has started. Monday...Northwest winds will bring another dry airmass into the state. Although some high based diurnal cumulus will pop with the heat of the day, skies will remain mostly clear to partly cloudy which should help temps rebound into the middle 40s to middle 50s. .LONG TERM...Monday Night Through Sunday Issued at 238 PM CDT Sun May 10 2020 Potential frost/freeze headlines and elevated fire weather conditions will be the concern into Tuesday, followed by a milder and somewhat wetter pattern for the rest of the week. A weak cold front is expected to move through the region Monday night, but skies will remain clear to partly cloudy. Lowered the blended forecast temperatures a bit, especially in the typical cold spots of north-central WI. A hard freeze looks like a good bet, especially northwest of the Fox Valley/lakeshore areas. Expect a slight moderation in temperatures on Tuesday, with highs in the 50s, and another day of very low relative humidity in the sandy soil regions. Dry conditions should persist through Tuesday night, but low temperatures should not be as cold due to WAA and increasing high clouds late. Even so, suspect we will still need at least frost advisory headlines. Strong return flow is expected to develop Wednesday afternoon and night, as the surface high shifts into the eastern Great Lakes and a 30-40 knot low-level jet develops. This will bring a swath of showers through the forecast area. The showers should diminish somewhat overnight as the low-level jet veers west. Models offer differing solutions on Thursday and Thursday night. The GFS is farther north with a surface low and associated warm front, and brings significant QPF to most of the region Thursday afternoon and evening. The ECMWF is farther south and much drier, with showers mainly impacting our southeast counties. Due to the uncertainty, we stayed close to the blended model pops during this period. Milder temperatures in the 60s are anticipated, though precipitation trends will have an impact on this. Friday looks like the best bet for a dry day late in the week, as weak high pressure arrives. Could see a few of our typical warm spots reach into the lower 70s. Seasonal temperatures and small precipitation chances are anticipated for the weekend, with high temperatures reaching 65 to 70 degrees away from Lake Michigan. && .AVIATION...for 00Z TAF Issuance Issued at 542 PM CDT Sun May 10 2020 Clouds will gradually diminish from north to south late this evening as drier air filters in from Canada. The mid cloud deck around 4-5kft will lift through late this evening allowing all locations to remain VFR. This trend is expected through the remainder of the TAf period with good flying conditions expected. && .FIRE WEATHER... Issued at 238 PM CDT Sun May 10 2020 Elevated fire weather conditions are expected on Monday and Tuesday. Relative humidities should drop into the 15 to 25 percent range in the sandy soil regions both days, but winds should only be moderate from the west-northwest, with gusts to 15 to 20 mph. && .GRB WATCHES/WARNINGS/ADVISORIES... Freeze Warning from 2 AM to 8 AM CDT Monday for WIZ020-022-030- 031-035>040-045-048>050-073-074. && $$ SHORT TERM.....MPC LONG TERM......Kieckbusch AVIATION.......Cooley FIRE WEATHER...Kieckbusch
Area Forecast Discussion
National Weather Service Louisville KY
921 PM EDT Sun May 10 2020 .Forecast Update... Issued at 919 PM EDT Sun May 10 2020 Surface front and associated showers have exited our CWA as satellite shows mostly clear skies over the area. Winds are still gusting into the 25-30mph range but are expected to decrease within the next couple of hours. Have updated the near term grids and will also update the HWO to remove any mention of hazardous weather. Issued at 701 PM EDT Sun May 10 2020 Latest surface analysis shows the surface low centered over Lake Erie with the cold extending SW through OH and bisecting LMK`s CWA, lying over FFT through BWG. Radar has shown some activity popping up over the Bowling Green area where the environment is characterized by meager SBCAPE (~200 J/kg) and respectable DCAPE (~700 J/kg). Surface heating has resulted in steep low level lapse rates, which has been able to mix down upper level energy and produce strong surface winds with gusts in the 30-35mph range. Not expecting these showers over BWG to do much as RAP soundings show slight warming between 850-700mb, which should provide enough capping to quell any vertical development. With that being said, wouldn`t rule out a rogue gust in the 40mph range as the larger showers collapse. Farther north over and east of the Bluegrass, showers and dissipating thunderstorms continue to move eastward. Had a couple reports of pea size hail in Fayette County with one report of half inch hail over Lexington. Since then, cells and associated lightning have decreased. Expect this trend to continue as the cold front pushes eastward out of our area by later this evening. Have updated forecast grids to make mention of showers and slight chance TS over BWG area. Also made small adjustments to sky and near- term grids. Otherwise, forecast is on track with winds decreasing within a couple hours after sunset. Updated products forthcoming. && .Short Term...(This evening through Monday) Issued at 247 PM EDT Sun May 10 2020 Have been watching a line of showers and thunderstorms form across southern Indiana ahead of a cold front. This line is expected to continue moving east and expanding over the next few hours. CAPE is over 250 J/kg with DCAPE values near 500 J/kg. This is due to the steep low level lapse rates allowing elevated wind energy to make it to the ground. A couple of SPS`s has been issued as we observe this taking place. Bowman Field in Louisville has already measured a wind gust of 42 mph. Winds this strong can knock loose tree limbs and unsecured items, but with that being said, not expecting much severe weather. Most of the wind gusts in the area have been closer to 30 mph. Tonight, the cold front makes its way through Kentucky allowing surface high pressure to occupy the Ohio Valley. This will provide clear skies tonight, but temperatures won`t drop like one might expect because 5-10 mph winds will keep the atmosphere more mixed. With radiative cooling limited, expect lows in the mid to upper 30s by morning. Tomorrow expect lots of sunshine. Winds remain from the northwest as the region remains in front of upper ridging and east of the surface high. High temperatures will probably be limited to the 50s by some afternoon cloud cover and the cool northerly breeze. .Long Term...(Monday night through Sunday) Issued at 243 PM EDT Sun May 10 2020 The cold upper trough that has been playing a role in our chilly weather recently will exit early in the long term and be replaced by weak ridging for much of the week...followed by zonal flow for the weekend. Still, we`ll have one more cold morning Tuesday with lows mostly in the 35 to 40 degree range. A dome of cold Canadian high pressure will be just about overhead at sunrise Tuesday with light winds. High clouds will begin to stream in, but there may be enough low level moisture to support the idea of some frost in the Blue Grass. Tuesday an upper wave over Texas will spread more clouds into our skies with a chance of rain moving in as the wave proceeds to the Lower Mississippi Valley Tuesday night into Wednesday. The upper ridge should then become more assertive Wednesday night through Thursday night, resulting in lower chances of rain. Flatter upper flow Friday through Sunday makes for a more difficult forecast. General pattern of small waves moving through the flow aloft plus surface high pressure off the southeast coast suggests warmer and more humid conditions (highs in the 80s, dew points in the 60s) with occasional shower and thunderstorm chances. && .Aviation...(00Z TAF Issuance) Issued at 735 PM EDT SUN May 10 2020 As per regional observations, the surface cold front is currently lying NE-SW roughly over FFT to BWG. Satellite imagery shows a line of agitated cumulus along and slightly ahead of the front while radar reveals these to only be showers at this point. Tight pressure gradient will see continued strong winds out of the WNW with gusts around 25-30kt beginning to decrease a couple hours after sunset. VFR conditions are expected throughout the TAF cycle, but winds will pick up again Monday late morning out of the WNW with gusts into the upper teens to around 20kt with a diurnal cu field popping up resulting in a FL050 CIG. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...CG Short Term...KDW Long Term...13 Aviation...CG
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
636 PM CDT Sun May 10 2020 .SHORT TERM...(This evening through Monday night) Issued at 218 PM CDT Sun May 10 2020 Visible imagery show extensive cloud cover across the area this afternoon, with diurnal enhancement of CU/TCU thanks to lingering cyclonic flow and good lapse rates with the upper cold pool overhead. The back edge to the most widespread shower activity is collocated with the back edge of the upper PV anomaly, per the RAP 2.0 PVU analysis. This will continue to push south this afternoon, taking showers out of the area as max daytime heating also winds down. We`ll see clouds stick around into the evening, but subsidence and increased low level ridging should work to scour them out as the night progresses. Near and below freezing temperatures look like a good bet overnight, so kept the Freeze Warning up for areas where sufficient green-up has occurred. The metro area should escape the coolest temperatures thanks to the UHI, but outlying areas could certainly get down into the upper 20s. Monday will be unseasonably cool but dry as northwest upper flow remains in place across the area. Monday night will bring another night of sub-freezing temperatures to most of the area, with another Freeze Warning looking all but certain for the same areas. .LONG TERM...(Tuesday through Sunday) Issued at 218 PM CDT Sun May 10 2020 Guidance continues to show the large scale mid/upper flow de- amplifying across the CONUS by midweek, with an upper trough approaching the west coast by week`s end. The main system of interest for our area looks to come midweek, when the initial strong return flow and warm advection sets up across the region. Widespread showers and a few thunderstorms can be expected with a broad area of warm advection and a somewhat muted moisture return per 850 mb theta-e forecasts. Better moisture/instability will be to our south, and better isentropic ascent will be to our north, so we could be split to some extent by where the heaviest precipitation occurs, but it still looks like we`ll have enough going on to get some precipitation, so high PoPs look like a safe bet Wednesday into Wednesday night. After that more spread becomes apparent in the guidance, which isn`t surprising given the more zonal flow and greater potential for timing and amplitude differences in the solutions. Stuck close to the consensus NBM guidance for the balance of the forecast, which results in a few periods of chance PoPs from Thursday into the weekend, but with generally moderating temperatures (back near or a bit above normal). && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 636 PM CDT Sun May 10 2020 Overcast clouds with a few breaks around 6000 feet AGL will gradually move out of the area and dissipate. Clouds have largely become stratocu and will take a little while longer to dissipate or depart amidst lingering cyclonic flow, but most areas should be scattering out from northwest to southeast between 06z-12z. Only some scattered high clouds are expected Monday, but the main concern will be northwest winds and to what extent they gust. Best chance for gusts near 20 knots Monday afternoon will be in western and south central MN. KMSP... VFR conditions throughout. Gusts will taper off this evening, though there may be some gusts to 16 kts or so through 02Z. Northwest flow persists through Monday, with more gusts up to 16 knots in the afternoon. After the clouds around 6k-7k feet AGL depart late tonight, there should only be some scattered clouds Monday. /OUTLOOK FOR KMSP/ TUE...VFR. Wind NW 5 kts. WED...VFR. Chc of -RA/MVFR cigs. Wind SE 10-15G25 kts. THU...VFR. Wind SW 5-10 kts becoming NW. && .MPX WATCHES/WARNINGS/ADVISORIES... WI...Freeze Warning from 2 AM to 8 AM CDT Monday for WIZ023>028. MN...Freeze Warning from 2 AM to 8 AM CDT Monday for MNZ056>070- 073>078-082>085-091>093. && $$ SHORT TERM... LONG TERM... AVIATION...TDK
Area Forecast Discussion
National Weather Service Marquette MI
635 PM EDT Sun May 10 2020 .SHORT TERM...(This evening through Monday) Issued at 311 PM EDT SUN MAY 10 2020 The overall large-scale pattern of negatively tilted western U.S. ridging and broad eastern U.S. troughing continues tonight and tomorrow. Radar this afternoon shows scattered returns over the north wind snow belts, which have been observed to be a mix of snow showers and drizzle. This makes sense given HRRR and NAM profiles showing saturation to around -8 to -10 C resulting in the heavier convective cells producing snow and the weaker ones mostly producing drizzle. The last several runs of the HRRR have indicated that this low-level moisture will dry up after about 21-22z so have the chance and slight chance POPs ending around then. Tonight the next round of colder air aloft moves in, dropping 850 mb temps from about -7 C where they are now to around -12 C by early tomorrow morning. The short wave that ushers in this cold shot is rather weak, meaning there won`t be much wind aloft to mix down. Chances for renewed lake-effect showers look very low since the saturated layer is pretty thin and there is very dry air just above it. But it`s not impossible that there could be a few rogue flurries in the NNW wind LES belts tomorrow morning. Any lingering lake-effect clouds will clear out by mid to late morning. Despite the air aloft being colder tomorrow than today, temps tomorrow should actually be warmer thanks to the sunshine. Model profiles show mixing to at least 4000 feet and possibly even 600 feet or more (about 750 mb) which gets highs up to the mid 40s west and south. East and near Lake Superior highs will remain stuck in the 30s with onshore NW flow persisting through the day, but at least it won`t feel quite as cold with the bright May sun. This deep mixing plus the aforementioned very dry air aloft means the other thing to watch tomorrow will be just how dry it gets. For dew points, assumed mixing to about 6000 feet over the west which from NAM and GFS profiles would result in dew points falling into the low single digits. This translates to RH values between 15 and 20% over the west in the afternoon and 20-25% central and east. Wind, although not terribly strong, could still gust to 15-20 mph at times thanks to the mixing being so deep. Temps only being in the 40s will severely limit the fire weather potential despite these numbers, but can`t completely rule out any fire weather concern with those RH numbers. .LONG TERM...(Monday night through Sunday) Issued at 417 PM EDT SUN MAY 10 2020 Medium range model runs over the last 24hrs do not show any significant changes in the expected evolution of the pattern across N America. Unseasonably cold conditions are still underway across the Great Lakes region under a highly amplified pattern. This pattern features a sharply amplified ridge along the w coast of N America, extending n into the Arctic, with positive height anomalies linking to another positive height anomaly center over the N Atlantic in the vcnty of southern Greenland and Iceland. This continues to force deep troffing into se Canada, the Great Lakes region and New England, and thus the cold conditions. Over the next few days, a shortwave off the W Coast will cut into the western ridge over the western U.S., and positive height anomalies will shift n and strengthen/consolidate over the Arctic Ocean where 500mb height anomalies will increase to around 350m. This will work to suppress heights farther s across much of Canada this week. Combined with the loss of the western ridge, this spells a transition to a more zonally oriented flow across the northern Lower 48, and thus, warmer conditions are on the way for the Upper Lakes. Conditions will remain unseasonably cool thru Mon, then temps will gradually increase, reaching more typical mid May readings by late in the upcoming week. Normal mid May high temps across Upper MI are in the 60s, coolest closer to the Great Lakes. Farther down the line during the week of May 17, ensembles still indicate development of troffing into the western Lower 48 while some degree of ridging is noted to the n in western Canada. Which feature is more amplified will determine the temp outcome across Upper MI, but right now, it looks like temps during the week of May 17 will generally be around the mid to late May normals, potentially leaning above normal more days than not during that week, and early in that week, there could be a couple of warm days. As for pcpn, the transition to a more zonally oriented flow regime over the next few days will be a dry one. Next chc of meaningful pcpn will arrive late Wed/Thu when some of the shortwave energy cutting thru the western ridge streaks e to the Upper Lakes. Heading thru the weekend, potential of pcpn is much more uncertain. Beginning Mon night/Tue...models are in good agreement showing a vigorous vort max swiping far northern and eastern Lake Superior. Given the lack of moisture and with the fcst area situated on the right side of the vort track, don`t expect any synoptic pcpn with this feature. Wave will brush the area with one last reinforcing shot of colder air, possibly dropping 850mb temps to -12C. Combination of the vigorous wave, cold air and deeper moisture profile closer to the vort max track may be sufficient for some lake enhanced -shsn into the eastern fcst area during the night. To the w, dry air and mostly clear skies will result in another chilly night for mid May. Traditional interior cold spots may slip blo 20F. The colder air arriving Mon night will likely support stratocu expansion for a time after sunrise on Tue, mainly over the e half of the fcst area as daytime heating works on the moisture provided by the lake. Will be short-lived as the daytime heating then goes on to mix out the moisture as drier air is mixed down. Thus, expect a trend to sunny skies in those areas that see clouds in the morning. Speaking of the dry air, mix down potential of dry air will cause dwpts to fall in the aftn, probably to around 5F, if not lower, in the interior w half. With high temps pushing lwr 50s in that area (which will be the warmest across the fcst area), RH will fall to around 15pct. Combined with aftn winds gusting to 15-20mph, it will be a day of increased wildfire potential even though it will be cool. Although RH won`t be as low e, dropping to around 25pct, wildfire potential will be increased there as well. High temps will be lowest e near Lake Superior. Readings there will not get out of the 30s. High pres ridge over the area Tue evening will shift e during the night. So, the night will start quiet/calm and clear. As the ridge shifts e, expect some increase in winds w and n overnight. Also, high clouds will start to increase, at least over the w overnight, well in advance of shortwave approaching the Northern Plains. In the interior, clear skies/calm conditions will support one more unseasonably cold night. Traditional cold spots may drop into the teens. The transition to a more zonal pattern will bring a couple of shortwaves eastward, affecting the area late Wed/Thu. 12z medium range models maintain a consistent picture with the model runs viewed 24hrs ago. In response to the approaching waves, strengthening waa/isentropic ascent and moisture advection will likely spread rain into Upper MI late Wed into Thu. There are still some timing differences among the models, but that difference has narrowed. Overall, signal is there for at least a widespread light rain late Wed into Thu. GFS is stronger with the second shortwave, resulting in an increase in rain Thu evening. Leaned fcst toward the more consistent ECMWF which is weaker with the second wave and thus quicker drying things out for Thu night. Fri thru the weekend, no consistent model trends have emerged, except for a drier signal on Fri due to increased agreement for sfc high pres to pass over the Upper Lakes. Based on recent days medium range guidance, there will be a potential of -shra at some point over the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 635 PM EDT SUN MAY 10 2020 Will be VFR conditions for most of the forecast period. There could still be a brief MVFR condition at the beginning of this forecast period, but do not have that in there as will be very brief indeed. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 311 PM EDT SUN MAY 10 2020 NW winds around 15 kts west half and 25 kts east half this evening will veer to NNE tonight but remain around 20 kts give or take. Winds then back to SW on the west half and relax to around 15 kts Monday. On the east half winds veer to NW but stay around 20-25 kts. Except for another brief period of winds up to 25 kts on the east half late Monday night into early Tuesday morning, winds across the lake are expected to stay at or below 20 kts through the end of the week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...RJC LONG TERM...Rolfson AVIATION...07 MARINE...RJC
National Weather Service Morristown TN
1020 PM EDT Sun May 10 2020 .UPDATE... EVENING UPDATE. && .DISCUSSION... A cold front will be moving through the area over the next few hours. Showers associated with the front will affect areas north of I-40 tonight, with light QPF amounts. The front should clear the area by 09Z. Overall, the forecast is on track and only a few small tweaks will be needed, mainly to hourly temps and dewpoints. DGS && .AVIATION... 00Z TAF DISCUSSION. VFR conditions are forecast through the period, but broken to overcast clouds around 5kft will be moving in at TRI and TYS overnight. A few showers may occur in the vicinity of TRI. SW winds this evening will shift to W-NW as a cold front moves through, and winds will be in the 8-12 kt range through tomorrow, gusting at times to 20-25 kts at TRI. DGS && .PREV DISCUSSION... /ISSUED 329 PM EDT Sun May 10 2020/ SHORT TERM (This Afternoon through Sunday)... Another day of below average temperatures across the southern Appalachians. As of 3 pm, temperatures are currently in the 60s for most locations but average highs this time of year average in the 70s. The atmosphere is very dry with PW values in the 0.4-0.5 inch range but moisture will be on the increase later this evening into the overnight hours. Current water vapor and RAP upper air analysis, indicate an upper level trough to the north across the Great Lakes. This trough is forecast to continue to track to the southeast into the Ohio River Valley later tonight into early Monday. At the surface, high pressure has shifted to the east with southerly to southwesterly low-level flow across the region. A front is located to the west in association with the upper level trough. This front is moving into KY/TN and will continue to track eastward. Radar imagery indicates a few returns extending along the front from the Great Lakes southward into Kentucky. The returns along the southern end are very light. For now, have continued with 20-40 PoPs this evening and overnight mainly for locations north of I-40. Model soundings indicate that saturation is rather shallow and only expect rainfall amounts of a few hundredths of an inch. The cold front will sweep through the region overnight bringing in a reinforcing shot of cold air. Strong cold advection early Monday morning will drop lows into the mid 30s to low 40s for most locations. Does not look like frost will be a possibility due to 5-15 mph westerly to northwesterly winds overnight. Look for sunny skies once again on Monday as dry air sweeps in behind the departing front with the cold airmass. PW values will drop back down into the 0.2-0.3 inch range. Temperatures at 850 mb will range anywhere from -5 to 0 degrees Celsius. These temperatures are near the minimum climatologically for mid-May and would be near the 25th percentile for late January to give a reference for just how cold and dry the atmosphere will be on Monday. Despite the ample sunshine, highs on Monday will be well below normal in the mid 50s for low 60s. MA LONG TERM (Monday night through Sunday)... The start of the extended period will be highlighted by cold temperatures as upper trough over the eastern states lingers one more night and dry airmass allows for good radiational cooling Monday night with frost possible across northeast third of the forecast area. NAM/GFS models begins to bring in some moisture to western and southern sections late Monday night with some cloud cover which will keep temperatures warmer in those areas. Ecmwf keeps drier airmass over northern sections with prevailing northwesterly flow. Tuesday and Tuesday night models try to bring moisture north as southerly flow develops with light showers developing with the best chance south Tuesday and then northern sections northeast Tuesday night. Think the surface high will be too strong and moisture return will be slower than models suggest Tuesday so will keep pops low. Tuesday night went with low pops as guidance still seems overdone. Wednesday and Wednesday night warm front to move across the region with small rain chances to continue. Temperatures Tuesday and Wednesday will slowly warm from upper 50s to mid 60s to mid 60s to mid 70s but still below normal. Thursday much warmer temperatures as large Atlantic high brings whole area into south to southwest moist flow off the gulf of Mexico. A system develops over the southern plains and moves slowly northeast. The associated front makes little process east so increasing chance for showers and thunderstorms. This activity will be largely diurnal. Only slight chance precipitation Thursday mainly northeast then Friday highest chances mountains and northern plateau. Saturday and Sunday increasing rain chances for all areas. Temperatures will warm to above normal the last 3 days with highs in the mid to upper 80s. TD && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$
Area Forecast Discussion
National Weather Service Tulsa OK
940 PM CDT Sun May 10 2020 ...UPDATE... .DISCUSSION... This evening some patchy drizzle/very light rain had developed along a weak 850mb-700mb frontogenetic forcing axis positioned northwest to southeast from North Central to East Central Oklahoma. Meanwhile...the surface cold front had shifted south of the Red River with northerly winds common across the CWA. North of the mid level boundary...skies were mostly clear...while along and south of the boundary...partly to mostly cloudy skies were observed. Through the late evening hours the mid level frontogenetic forcing band is expected to continue to weaken...which can be seen by recent radar trends...with only a slight chance of a few sprinkles lasting into the overnight hours. Overnight tonight...a vort max within the upper level northwesterly flow is forecast to push into the region with additional chances for rain showers across Northeast Oklahoma. There may be a chance that some precip makes it into far Northwest Arkansas by 12z...if the latest runs of the HRRR verify. For now have extended pops east to the Arkansas border with the greater chances along the Oklahoma Kansas border late tonight into Monday morning. Cloud cover is also expected to increase overnight while at the same time light surface winds become more easterly. Before the additional clouds move in during the night...surface temps look to fall into the 40s across much of the CWA before slightly warming or becoming nearly steady under the cloud cover late tonight. Have added minor adjustments to hourly temp/dewpoint/sky/wind grids based on the mentioned above and ingested observations. The rest of the forecast seems to be in good shape at this time. && .PRELIMINARY POINT TEMPS/POPS... TUL 46 53 47 54 / 30 60 80 80 FSM 48 59 47 55 / 10 30 50 80 MLC 47 63 52 59 / 10 20 50 80 BVO 43 49 45 55 / 40 70 90 70 FYV 39 51 45 52 / 10 50 80 80 BYV 38 49 43 50 / 10 50 90 80 MKO 46 57 47 55 / 10 40 70 80 MIO 38 49 45 54 / 20 60 90 80 F10 46 57 49 56 / 10 40 70 90 HHW 50 68 54 67 / 0 0 30 70 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...20