FXUS63 KLSX 281749 AFDLSX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ST LOUIS MO 1249 PM CDT SUN APR 28 2013 .UPDATE... ISSUED AT 1235 PM CDT SUN APR 28 2013 MADE A FEW CHANGES TO THE REST OF THE DAY...MAINLY TO KEEP CLOUDS HANGING IN LONGER AND TO LOWER TEMPERATURES A FEW DEGREES. THE WESTERN EDGE OF THE CLOUDS BLEW UP WITH DIURNAL STRATO-CU DEVELOPMENT A COUPLE OF HOURS AGO...AND IT SIMPLY HASN'T BEEN MOVING AS FAST AS EARLIER ANTICIPATED. CURRENT THINKING IS THAT THE VERY SLOW EASTWARD PROGRESSION WILL CONTINUE TODAY...AND THEN THE DIURNAL CLOUDS WILL DISSIPATE PRETTY RAPIDLY AFTER 00Z. CARNEY && .SHORT TERM...(THROUGH LATE THIS AFTERNOON) ISSUED AT 315 AM CDT SUN APR 28 2013 AREAS OF DRIZZLE AND ISO-SCT RAIN SHOWERS SHOULD FINALLY END TODAY AS A SLOW-MOVING LOW PRESSURE SYSTEM CONTINUES MOVING AWAY FROM THE AREA. RAP BUFKIT PROFILES SHOW MIXING TO AROUND H9 THEREFORE HIGHS IN THE LOW/MID 60S TO AROUND 70 LOOK REASONABLE CONSIDERING INITIAL CLOUD COVER AND MOIST LOW LEVELS FM RECENT RAINFALL. TEMPERATURES WILL BE WARMER IN CENTRAL MO THAN IN SWRN IL BECAUSE OF QUICKER CLEARING IN THE WESTERN CWA. KANOFSKY .LONG TERM...(TONIGHT THROUGH SATURDAY) ISSUED AT 315 AM CDT SUN APR 28 2013 (TONIGHT - WEDNESDAY) UPPER LEVEL RIDGE WILL BUILD OVER ERN NOAM EARLY IN THE PERIOD AND THEN PROCEED TO DOMINATE THRU THE MIDDLE OF THE WEEK...WITH A TROF BUILDING OVER THE NWRN CONUS INITIALLY...BUT DEEPENING WITH TIME AS IT SLOWLY TRANSLATES EWD INTO THE HI PLAINS BY WEDNESDAY. THIS SHOULD GIVE US A PERIOD OF WARM AND MAINLY DRY WX. THE WARMER MAV MOS IS A GOOD PLACE TO START FOR MONDAY AND TUESDAY MAX TEMPS...BUT IN SEVERAL LOCALES...WENT A COUPLE DEGS HIGHER TO SUPPORT H900-850 TEMPS ALOFT DEPICTED BY THE MODELS AND ANTICIPATED SUNSHINE. LOOK FOR UPR 70S-LO 80S ON MONDAY WITH MID 80S TUESDAY WITH A MORE SW WIND EXPECTED. AN OUTSIDE CHANCE AT UPR 80S WILL PRESENT ITSELF FOR PARTS OF STL METRO TUESDAY. LOSS OF W COMPONENT TO SFC WND ON WEDNESDAY AND SOME UNCERTAINTY ON WHERE FRONT WILL BE...HAVE 80-85F FCSTD FOR MOST SPOTS. TWO SMALL WINDOWS OF OPPORTUNITY FOR RAIN THIS PERIOD. THE FIRST IS ON MONDAY AFTERNOON-NIGHT. MODELS ALL SHOW PRETTY STOUT INSTABILITY AND 0-6KM BULK SHEAR OF 30-35KTS IN PLACE AHEAD OF WHAT SHOULD BE A CDFNT EDGING INTO THE NWRN FA BY LATE MONDAY AFTERNOON BEFORE IT STALLS AND WASHES OUT MONDAY NIGHT. HOWEVER...SOME OF THESE LARGE INSTABILITY VALUES ARE PREDICATED ON WHAT LOOKS TO BE A TOO AGGRESSIVE LO LEVEL MOISTURE RETURN...AND A DEPENDENCE IN PART ON SFC DWPTS REACHING INTO THE MID-UPR 60S. HOWEVER...LO LEVEL MASS FIELDS DO NOT SUPPORT A LO LEVEL MOISTURE RETURN OF THAT MAGNITUDE WITH WEAK FLOW AND A WEAK BLOCKING RIDGE NEAR THE GULF OF MEXICO UNTIL MONDAY AFTERNOON AND THEN IT SHOULD BE TOO SMALL A TIME PERIOD TO GET THE RICH MOISTURE THAT FAR N. SFC DWPTS INSTEAD EDGING NEAR 60F LOOK MORE LIKELY BUT THIS WILL STILL YIELD CINH VALUES AT OR ABOVE 20 J/KG WHICH WILL PROBABLY BE ALL IT WILL NEED TO BLOCK MOST CONVECTION WITH A WEAKENING SFC FRONT. BUFR SOUNDINGS BASED ON OUR LOCAL WRF DEPICT THIS WELL. SO...IF SOMETHING CAN POP...IT SHOULD SUPPORT DAY SHIFT YESTERDAY/S ASSERTION WITH DECENT CHANCE OF IT GOING TO SEVERE...BUT OCCURRENCE OF ANY CONVECTION LOOKS TO BE PRETTY LIMITED. AFTER SUNSET MONDAY EVENING...CINH RAPIDLY INCREASES WITH THE SFC FRONT STARTING TO WASH OUT...AND SO WINDOW FOR CONVECTION WILL RAPIDLY CLOSE. MADE MINIMAL CHANGES TO PREVIOUS FCST WHICH ALREADY HAD MINIMAL CHC POPS LIMITED TO THE NW FA. STILL SOME MODEL DIFFS ON TIMING OF THE SFC CDFNT FOR MID-LATE WEEK...WITH THE GFS CONTINUING TO BE THE FASTEST INTO OUR AREA BY WEDNESDAY AFTERNOON WITH THE ECMWF SOME 12HRS LATER INTO EARLY THURSDAY MORNING. BACKED OFF SOME ON POPS FOR WEDNESDAY WITH THE ECMWF CONTINUING TO LEAD THE GFS TO WHAT HOPEFULLY WILL BE THE VERIFYING SOLN...WHICH HAS STEADILY BEEN FAVORING A SLOWER FROPA. (THURSDAY - SATURDAY) LOOKING INCREASINGLY LIKE A COOL AND WET PERIOD. THE LARGE DISCREPANCY ON WHEN AND WHERE TO FORM THE CUTOFF LO HAS BEEN OVERCOME FOR THE MOST PART WITH THE GFS FOLLOWING THE ECMWF/S LEAD FOR A MORE RAPID FORMATION...AND FURTHER W AS A RESULT. STILL SOME SMALL DIFFS AND EXPECT TO SEE SOME WOBBLING THE NEXT DAY OR TWO. UNFORTUNATELY...WHEN DEALING WITH CUTOFF UPPER LOWS...EVERY WOBBLE WILL MAKE A PRETTY BIG DIFFERENCE ON RAIN CHCS AND TEMPS. THE LATEST ITERATION FROM THE 00Z MODELS HAS A GENERAL CONSENSUS ON THE UPPER LO FORMING AROUND THE INTERSECTION OF KS-MO-OK-AR ON FRIDAY AND THEN GRADUALLY PULLING NWD THRU SATURDAY. THOSE SLIGHT DIFFS WILL MAKE A BIG DEAL AT THE SFC...WHERE ECMWF SHOWS A MORE AGGRESSIVE CDFNT PUSH ON THURSDAY WITH NOTHING OF THE SORT FROM THE GFS AND SO A LARGE TEMP FCST DIFF AS A RESULT ARISES...ESPECIALLY THURSDAY NIGHT AND FRIDAY. A BROAD CONSENSUS APPROACH PREFERRED FOR TEMPS AS A RESULT. ONE THING THAT LOOKS INCREASINGLY LIKELY IS THE RAIN CHCS... ESPECIALLY IF THE UPPER LO SETS UP IN THE RIGHT SPOT ALMOST LIKE MODELS DEPICT NOW...COULD BE SOME HEAVY RAINFALL POTENTIAL AS IT TAPS INTO GULF OF MEXICO MOISTURE. TES && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1235 PM CDT SUN APR 28 2013 MVFR FLIGHT CONDITIONS WILL PREVAIL ACROSS MUCH THE AREA FOR THE REST OF THE DAY...WITH PATCHES OF IFR CONTINUING OVER PARTS OF SOUTHWEST ILLINOIS. CONDITIONS WILL GRADUALLY IMPROVE THROUGH THE AFTERNOON...WITH MOST OF THE AREA CLEARING OUT BY MID-LATE EVENING. EXPECT SOME MVFR FOG ALONG AND EAST OF THE MISSISSIPPI RIVER LATE TONIGHT WITH AREAS OF IFR PROBABLY DEVELOPING OVER PARTS OF SOUTHWEST/SOUTH CENTRAL ILLINOIS WHERE THE WIND WILL BE LIGHTEST. SPECIFICS FOR KSTL... MVFR CIGS BELOW 2000FT WILL PREVAIL FOR A FEW MORE HOURS AT LAMBERT BEFORE LIFTING ABOVE 2000FT. CURRENT THINKING IS THAT CLOUDS SHOULD SCATTER OUT EARLY THIS EVENING. NOT SURE WHAT TO DO ABOUT FOG POTENTIAL AT THIS TIME. THINK THERE WILL BE FOG IN THE STL METRO AREA...MOST LIKELY 3-5SM VSBYS...BUT LAMBERT TENDS TO BE LESS FOGGY THAN OTHER STATIONS. HAVE NOT INCLUDED FOG IN THE CURRENT TAF...BUT WILL MENTION FOG POTENTIAL TO THE EVENING SHIFT. CARNEY && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX  FXUS63 KLSX 282013 AFDLSX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 313 PM CDT SUN JUL 28 2013 .SHORT TERM...(THROUGH LATE TONIGHT) ISSUED AT 300 PM CDT SUN JUL 28 2013 ANOTHER TRANQUIL NIGHT ON STORE ACROSS THE REGION WITH MOST OF THE ACTION EXPECTED TO REMAIN WELL TO THE WEST. THE DEEP UPPER LOW CURRENTLY CENTERED IN THE GREAT LAKES REGION WILL MOVE EASTWARD TONIGHT AND THIS WILL BRING RISING HEIGHTS AND BACKING MID/UPPER LEVEL FLOW. THIS CHANGE IN THE FLOW WILL ALLOW THE STREAM OF MID AND HI CLOUDS NOW SITUATED FROM KS THRU SW MO TO SLOWLY SHUNT NORTHWARD. HOW COOL IT GETS TONIGHT WILL DEPEND ON HOW QUICKLY THE CLOUDS INCREASE...BUT IN GENERAL THE REGION WILL ONCE AGAIN EXPERIENCE BELOW AVERAGE TEMPERATURES TONIGHT...ALBIET NOTHING LIKE THOSE OF LAST NIGHT/EARLY THIS MORNING. PRECITATION CHANCES TONIGHT APPEAR TO BE CONFINED TO PORTIONS OF CENTRAL MO AFTER 08-09Z. THE WEAK DISTURBANCE ALOFT NOW EXITING ERN CO IN TANDEM WITH A STRENGTHENING S/SWLY LLJ IS EXPECTED TO PRODUCED A NEW REGION OF SHOWERS AND THUNDERSTORMS ACROSS NORTHERN KS LATER TONIGHT. THIS AREA OF SHOWERS AND THUNDERSTORMS SHOULD MOVE AND EXPAND EASTWARD INTO NW MO AFTER MIDNIGHT AS THE LLJ VEERS...WITH THE LEADING EDGE POSSIBLY INTO THE FAR WESTERN CWA BY DAYBREAK. GLASS .LONG TERM...(MONDAY THROUGH NEXT SUNDAY) ISSUED AT 300 PM CDT SUN JUL 28 2013 A STORMY PERIOD STILL LOOKS ON TAP FOR THE PERIOD MONDAY INTO TUESDAY NIGHT. THE ONGOING AREA OF SHOWERS/THUNDERSTORMS CENTERED IN THE VICINITY OF NW MO AT DAYBREAK MONDAY WILL CONTINUE TO SPREAD/DEVELOP EASTWARD IN ASSOCIATION WITH VEERING AND WEAKENING LOW LEVEL FLOW AND THE PROGRESSION OF THE UPPER DISTURBANCE WITH THE HIGHEST POPS ALONG AND NORTH OF I-70. THERE MAY BE A LULL IN PRECIPITATION/COVERAGE DURING THE FIRST PART OF THE EVENING ON MONDAY BUT ADDITIONAL WEAK SHORT WAVES WITHIN THE FLOW ALOFT AND A STOUT AND VEERING S/SWLY LLJ WILL PROVIDE STRONG FORCING FOR ADDITIONAL CONVECTIVE CLUSTERS AND LARGER MCSS FROM LATER MONDAY EVENING INTO TUESDAY...BOTH DEVELOPING AND MOVING INTO THE AREA FROM THE WEST. THE MODELS DIVERGE SOME ON THE PLACEMENT OF HIGHEST QPF AND ULTIMATELY THIS WILL BE REGULATED BY MESOSCALE FACTORS. AT THIS TIME IT WOULD APPEAR THE MOST FAVORED LOCATION WOULD BE ALONG AND SOUTH OF I-70 WHERE THE LOW LEVEL FORCING WILL REMAIN MOST CONCENTRATED IN CONJUNCTION WITH PWS AOA 2 INCHES AND DEEP WARM CLOUD DEPTHS. IT STILL LOOKS LIKE BY WEDNESDAY THE MAIN THREAT OF MEASURABLE PRECIPITATION WILL BE TO THE EAST OF THE CWA WITH THE PASSAGE OF THE UPPER SHORT WAVE AND ASSOCIATED SURFACE LOW. AFTER A DRY DAY AND MODERATION IN TEMPERATURES ON THURSDAY...A NEW SYSTEM WILL IMPACT THE AREA FROM FRIDAY AFTERNOON INTO THE WEEKEND ACCOMPANIED BY A CHANCE OF SHOWERS AND THUNDERSTORMS. FROM NEXT WEEKEND AND BEYOND THE MAJORITY OF THE GLOBAL MODEL GUIDANCE SHOWS A FAMILIAR PATTERN WE HAVE SEEN THIS SUMMER...A MEAN VORTEX IN EASTERN CANADA AND BROAD UPPER TROFFING THRU THE EASTERN U.S.. THIS UPPER AIR REGIME WOULD GENERALLY FAVOR AVERAGE TO BELOW AVERAGE TEMPERATURES INTO THE FIRST WEEK IN AUGUST. GLASS && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON) ISSUED AT 1249 PM CDT SUN JUL 28 2013 WEAK FRONTAL BOUNDARY TO REMAIN OVER FORECAST AREA STALLED OUT ALONG I-70 CORRIDOR. FOR MOST OF FORECAST PERIOD...TO REMAIN DRY WITH VFR CONDITIONS. LATER IN THE FORECAST PERIOD...WILL SEE ACTIVITY FIRE ON NOSE OF LOW LEVEL JET LATE TONIGHT OVER EASTERN KS...THEN SLIDE EAST TOWARDS FORECAST AREA. TIMING AND COVERAGE STILL HARD TO PIN DOWN. BEST CHANCES OF PCPN WILL BE OVER CENTRAL MO TOWARDS DAYBREAK...THEN CONTINUE TO SPREAD EAST TOWARDS KUIN AND STL METRO AREA BY END OF FORECAST PERIOD. SO FOR NOW JUST HAVE VCNTY SHOWER MENTION IN THOSE AREAS. OTHERWISE...WEST WINDS TO BECOME LIGHT AND VARIABLE OVERNIGHT...BEFORE PICKING BACK UP FROM THE EAST TO SOUTHEAST MONDAY MORNING. SPECIFICS FOR KSTL...WEAK FRONTAL BOUNDARY TO REMAIN OVER FORECAST AREA STALLED OUT ALONG I-70 CORRIDOR. FOR MOST OF FORECAST PERIOD...TO REMAIN DRY WITH VFR CONDITIONS. LATER IN THE FORECAST PERIOD...WILL SEE ACTIVITY FIRE ON NOSE OF LOW LEVEL JET LATE TONIGHT OVER EASTERN KS...THEN SLIDE EAST TOWARDS METRO AREA. TIMING AND COVERAGE STILL HARD TO PIN DOWN. BEST CHANCES OF PCPN WILL BE OVER CENTRAL MO TOWARDS DAYBREAK...THEN CONTINUE TO SPREAD EAST TOWARDS METRO AREA BY 16Z-17Z TIMEFRAME. SO FOR NOW JUST HAVE VCNTY SHOWER MENTION. OTHERWISE...WEST WINDS TO BECOME LIGHT AND VARIABLE BY 03Z MONDAY...BEFORE PICKING BACK UP FROM THE SOUTHEAST BY 17Z MONDAY. BYRD && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX  FXUS63 KLSX 132034 AFDLSX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 334 PM CDT Sat Jun 13 2015 .SHORT TERM: (Through Late Tonight) Issued at 334 PM CDT Sat Jun 13 2015 Currently tracking a subtle vort max/MCV over far NE Oklahoma at 1900 UTC tracking NNE. Thinking this feature will help focus the more widespread activity through the evening hours...predominantly over central Missouri early this evening and then toward portions of northeast Missouri and west-central Illinois late this evening. NAM model in terms of placement/amounts looks very reasonable based on current radar/WV imagery and followed fairly closely for PoPs/QPF tonight.Further south and east...more scattered showers and storms are possible anytime...but moreso before 0600 UTC. Concern tonight will once again focus in on heavy rainfall potential. Atmosphere this evening will be conducive to heavy rainfall rates due to very deep warm cloud depths...tall/thin CAPE profiles...and PWAT values above the 90th percentile of climatology. Locally/isolated heavy rainfall does appear possible tonight...but not sure how widespread any heavy rainfall will be tonight nor the track of heaviest QPF axis so did not issue a flash flood watch. However...portions of northeast Missouri and west-central Illinois especially would need to be monitored as 3-hr FFG values are only around 2 inches. Temperature wise...another very mild night is in store with lows generally in the low to mid 70s. Lows could reach mid to upper 60s however in regions which receive substantial rainfall. Gosselin .LONG TERM: (Sunday through Next Saturday) Issued at 334 PM CDT Sat Jun 13 2015 (Sunday-Tuesday) More diurnally-driven convection should fire up on Sunday...though expect coverage to be a bit less than today (and perhaps a bit later too) due to more cloud cover/less instability as well as weaker low-level convergence. That being said...still a good bet for afternoon showers/storms across central and northeast Missouri in addition to west-central Illinois which will be in closer proximity to both the synoptic quasi-stationary front and mid/upper level shear axis. Due to clouds...highs will be in the mid 80s for the most part though enough sunshine could boost some areas to near 90 degrees. Model uncertainty begins to increase already by Sunday night as the location of the synoptic frontal boundary (mainly how far southeast and how fast?) is highly unknown. GFS progresses the front a bit further to the southeast into our CWA a bit quicker on Sunday night. Strength of anticyclone aloft with SW flow aloft will make it difficult for the front to go too far southeast...at least without organized convection which could then develop a cold pool. Once again...northwestern third of the CWA will be in the best position for showers and storms on Sunday night...especially late night...and have likley PoPs up that way. With several periods across portions of northeast Missouri and west-central Illinois of likely PoPs...future shifts may need to issue a flash flood watch for these areas if multiple rounds of storms do indeed occur or look like they will occur as FFG values would only then further decrease as soils further saturate. Not a whole lot of change looking at early next week. Location of frontal boundary at the surface is unknown but likely somewhere over the southeastern half of the CWA. Consequently...likely PoPs also sag a bit southward in time. Temperatures...moreso during the day...look to cool a bit due to an increase in both sky cover and precipitation chances. (Tuesday Night-Friday) Models really begin to diverge with respect of how to handle tropical disturbance after it comes ashore into Texas early next week. All medium to long range models now at least agree on that scenario...with the ECMWF coming on board with the 1200 UTC run today. European model is about 36-48 hours slower than GFS as it slowly moves northeastward into our area with the GEM in between the other two. Track is also unknown...with GEM the southernmost solution attm and mainly affecting areas just to the south of our CWFA. Needless to say...plenty of time to sort this particular system out but will have to be watched closely as it would have the potential to dump very heavy rainfall and aggravate already existing saturated soils and river flooding. Gosselin && .AVIATION: (For the 18z TAFs through 18z Sunday Afternoon) Issued at 1106 AM CDT Sat Jun 13 2015 Short term pattern changes little into Sunday. Long wave trof over the pacific northwest with short waves moving through the central rockies into the plains. Models have the general pattern, but have not initialized well and have a hard time identifying the individual waves. Main axis of precipitaiton should be along the weak front which will be along a UIN to COU line today and slowy lift north tonight. Scattered tsra will fire in the warm unstable air south of the front this afternoon. NAM has consistently kept precip going from 00-06Z, so a late night vcty looks likey for at least UIN, and perhaps COU. Specifics for KSTL: Terminal stays in the warm unstable air south of the weak front. Overall, VFR with scattered tsra to fire by mid afternoon into the evening, with this repeating Sunday. More definitive systems looks to move into the area Sunday night into Tuesday. Exception today is the GFS which has high pops at 12z, with the NAM lower. This is a reversal of yesterday's 12z run. At this point am more inclined to keep any overnight tsra west of STL, given that the NAM has handled this better the last couple of days. Will not be a shock if it happens though. JPK && .PRELIMINARY POINT TEMPS/POPS: Saint Louis 74 87 76 85 / 40 50 50 60 Quincy 69 83 69 81 / 70 60 70 60 Columbia 69 84 70 82 / 70 60 60 70 Jefferson City 69 85 70 83 / 70 60 50 60 Salem 72 86 73 85 / 30 40 40 60 Farmington 71 86 71 85 / 30 50 40 60 && .LSX WATCHES/WARNINGS/ADVISORIES: MO...NONE. IL...NONE. && $$ WFO LSX  FXUS63 KLSX 140004 AFDLSX AREA FORECAST DISCUSSION...UPDATED AVIATION NATIONAL WEATHER SERVICE ST LOUIS MO 704 PM CDT Sat Jun 13 2015 .SHORT TERM: (Through Late Tonight) Issued at 334 PM CDT Sat Jun 13 2015 Currently tracking a subtle vort max/MCV over far NE Oklahoma at 1900 UTC tracking NNE. Thinking this feature will help focus the more widespread activity through the evening hours...predominantly over central Missouri early this evening and then toward portions of northeast Missouri and west-central Illinois late this evening. NAM model in terms of placement/amounts looks very reasonable based on current radar/WV imagery and followed fairly closely for PoPs/QPF tonight.Further south and east...more scattered showers and storms are possible anytime...but moreso before 0600 UTC. Concern tonight will once again focus in on heavy rainfall potential. Atmosphere this evening will be conducive to heavy rainfall rates due to very deep warm cloud depths...tall/thin CAPE profiles...and PWAT values above the 90th percentile of climatology. Locally/isolated heavy rainfall does appear possible tonight...but not sure how widespread any heavy rainfall will be tonight nor the track of heaviest QPF axis so did not issue a flash flood watch. However...portions of northeast Missouri and west-central Illinois especially would need to be monitored as 3-hr FFG values are only around 2 inches. Temperature wise...another very mild night is in store with lows generally in the low to mid 70s. Lows could reach mid to upper 60s however in regions which receive substantial rainfall. Gosselin .LONG TERM: (Sunday through Next Saturday) Issued at 334 PM CDT Sat Jun 13 2015 (Sunday-Tuesday) More diurnally-driven convection should fire up on Sunday...though expect coverage to be a bit less than today (and perhaps a bit later too) due to more cloud cover/less instability as well as weaker low-level convergence. That being said...still a good bet for afternoon showers/storms across central and northeast Missouri in addition to west-central Illinois which will be in closer proximity to both the synoptic quasi-stationary front and mid/upper level shear axis. Due to clouds...highs will be in the mid 80s for the most part though enough sunshine could boost some areas to near 90 degrees. Model uncertainty begins to increase already by Sunday night as the location of the synoptic frontal boundary (mainly how far southeast and how fast?) is highly unknown. GFS progresses the front a bit further to the southeast into our CWA a bit quicker on Sunday night. Strength of anticyclone aloft with SW flow aloft will make it difficult for the front to go too far southeast...at least without organized convection which could then develop a cold pool. Once again...northwestern third of the CWA will be in the best position for showers and storms on Sunday night...especially late night...and have likley PoPs up that way. With several periods across portions of northeast Missouri and west-central Illinois of likely PoPs...future shifts may need to issue a flash flood watch for these areas if multiple rounds of storms do indeed occur or look like they will occur as FFG values would only then further decrease as soils further saturate. Not a whole lot of change looking at early next week. Location of frontal boundary at the surface is unknown but likely somewhere over the southeastern half of the CWA. Consequently...likely PoPs also sag a bit southward in time. Temperatures...moreso during the day...look to cool a bit due to an increase in both sky cover and precipitation chances. (Tuesday Night-Friday) Models really begin to diverge with respect of how to handle tropical disturbance after it comes ashore into Texas early next week. All medium to long range models now at least agree on that scenario...with the ECMWF coming on board with the 1200 UTC run today. European model is about 36-48 hours slower than GFS as it slowly moves northeastward into our area with the GEM in between the other two. Track is also unknown...with GEM the southernmost solution attm and mainly affecting areas just to the south of our CWFA. Needless to say...plenty of time to sort this particular system out but will have to be watched closely as it would have the potential to dump very heavy rainfall and aggravate already existing saturated soils and river flooding. Gosselin && .AVIATION: (For the 00z TAFs through 00z Sunday Evening) Issued at 703 PM CDT Sat Jun 13 2015 Scattered storms beginning to taper off, so just have vicinity thunderstorm mention for most taf sites, though more predominent rain/storms moving into KUIN through about 03z Sunday, so have tempo group there. Otherwise, south to southwest wind to persist with next chance for storms by Sunday afternoon, so kept vicinity thunderstorm mention. With rainfall today, some patchy fog is possible so kept mention in KCOU and KUIN between 11z and 13z Sunday. Specifics for KSTL: Scattered storms beginning to taper off, so just have vicinity thunderstorm mention for metro area through 03z Sunday. Otherwise, south to southwest wind to persist with next chance for storms by Sunday afternoon, so kept vicinity thunderstorm mention after 19z Sunday. Byrd && .LSX WATCHES/WARNINGS/ADVISORIES: MO...NONE. IL...NONE. && $$ WFO LSX  FXUS63 KLSX 172053 AFDLSX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 353 PM CDT Wed Jun 17 2015 .SHORT TERM: (Tonight through Thursday) Issued at 330 PM CDT Wed Jun 17 2015 The main batch of rain which moved across the area today has diminished in coverage and moved out of the CWA. Scattered showers and thunderstorms are still occurring in its wake with the thunder generally confined to far northern MO and far southeast MO where heating has pushed SBCAPE over 2000 J/KG. I think the thunder threat will diminish into the early evening with loss of instability however a persistent area from southeast KS through Lake of the Ozarks region towards St. Louis has me a little more worried. This is occuring on the poleward fringe of the anticyclonically curved LLJ within a broad region of weak lift. The models don't have much in that area this evening, but I think at least scattered coverage will persist near that axis into the early evening. Otherwise expecting the next thrust of more solid rainfall overnight, generally aligned along I-44 associated with another disturbance in the southwest flow aloft ahead of the Bill remnants and LLJ and aided by the entrance region of an ULJ extending into the OH Valley. The coverage and intensity of precipitation should increase on Thursday as weak disturbances aloft continue to track E/NE across the region and the broad southwesterly LLJ continues to focus lift/mcon across the southern half of the area, namely along and south of I-70. A deep moist layer/tropical plume and PWs near 2 inches will continue to support very efficient rainfall production. Glass .LONG TERM: (Thursday Night through Next Wednesday) Issued at 330 PM CDT Wed Jun 17 2015 The rainfall over the last 30 hours, which has generally been in the 1-3 inch range, and another 1-2+ tonight into Thursday will result in well saturated soils and set the stage for a period of potentially serious flash flooding. Small creeks and streams and the quick response rivers are sure to experience flash flooding as will low-lying poor drainage areas. Residents should be reminded to avoid low water crossings and not attempt driving through water of unknown depth. Moderate to Major river flooding is forecast this weekend on some of the larger rivers. Although there remain some track and timing differences still yet to be completely resolved, the general consensus of the model guidance is the remnants of TS Bill will make the right turn towards MO Thursday night and slowly track across southern MO and southern IL Friday and Friday night. The ECMWF has been weighted highest given its persistence with track and typical superiority in handling tropical and remnant tropical systems. Very focused lift associated with the circulation, a increasing southerly LLJ on the east side, and a downstream ULJ will produce concentrated heavy rainfall from the northern through eastern semi-circle with the remnant low circulation. Another 3-5 inches of rainfall appears quite likely with locally higher totals given the very efficient rainfall production attendant with the lift magnitude/deep warm cloud depths/deep tropical moisture. The area we have been highlighting remains unchanged - the southern half of MO and southern IL. I have not extended the Flash Flood Watch into Friday night, but if this timing continues then it will need to be extended. If we get some heating on Friday and destabilization then we could also see a threat of a few tornadoes from low topped supercells - low level helicity will be quite high east of the remnant low. The impacts of Bill should be long gone by midday Saturday followed by a good warm-up and then a chance of showers and thunderstorms late Saturday into Monday with a wavering east-west front. By the middle of next week its time for big summer heat and humidity as a large high aloft shifts into the Mid MS Valley. Glass && .AVIATION: (For the 18z TAFs through 18z Thursday Afternoon) Issued at 1119 AM CDT Wed Jun 17 2015 Area of showers with a few embedded thunderstorms should shift east of COU around 18Z and move through the St Louis metro area this afternoon, clipping UIN on the northern fringes of the rain area. Should be mainly MVFR cigs this afternoon. The ceiling should rise into the VFR catagory this evening with a break in the rain. Another batch of showers and a few storms will move up from the southwest into our area late tonight and continue Thursday morning. The cloud ceilings may drop into the MVFR catagory early Thursday morning. Swly surface winds will continue through the period. Specifics for KSTL: Showers and a few storms will move through STL this afternoon with ceilings possibly dropping into the MVFR catagory. Another batch of rain with embedded storms will move up from southwest MO into STL by early Thursday morning. The ceiling height may drop into the MVFR catagory Thursday morning. A southwest wind will continue through the period. GKS && .LSX WATCHES/WARNINGS/ADVISORIES: MO...FLASH FLOOD WATCH through Friday evening FOR Boone MO-Callaway MO-Cole MO-Crawford MO-Franklin MO-Gasconade MO-Iron MO- Jefferson MO-Lincoln MO-Madison MO-Moniteau MO-Montgomery MO-Osage MO-Reynolds MO-St. Charles MO-St. Francois MO-St. Louis City MO-St. Louis MO-Ste. Genevieve MO-Warren MO- Washington MO. IL...FLASH FLOOD WATCH through Friday evening FOR Bond IL-Calhoun IL- Clinton IL-Fayette IL-Greene IL-Jersey IL-Macoupin IL- Madison IL-Marion IL-Monroe IL-Montgomery IL-Randolph IL- St. Clair IL-Washington IL. && $$ WFO LSX  FXUS63 KLSX 202048 AFDLSX Area Forecast Discussion National Weather Service Saint Louis MO 348 PM CDT Sun Aug 20 2017 .SHORT TERM... (Through Late Monday Afternoon) Issued at 348 PM CDT Sun Aug 20 2017 The outflow boundary from last night's MCS has pushed almost all the way through southeast through the forecast area, and the synoptic warm front is lifting back up through west central and northwest Missouri. A line of showers and thunderstorms is moving along the front from near Moberly up to near Maryville. The eastern end of the line appears to be weakening as it moves into more stable air behind the outflow boundary over our area. That being said...low level moisture convergence continues along the front through the rest of the afternoon...so I expect at least isolated to widely scattered convection to continue until at least 01-02Z this evening. across parts of central and northeast Missouri. The front will continue to lift northeast into Iowa tonight. All short range guidance is now showing moderate to strong moisture convergence over Iowa on the nose of a 30-40kt low level jet with precip breaking out between 04-06Z either over eastern Nebraska or northern/northwestern Iowa. CAMs also have some flavor of MCS over Iowa tonight. The strength and movement of the MCS tonight will be critical to what happens on Monday for the eclipse. The most likely scenario is that the MCS will push east-southeast tonight and early Monday morning as the low level jet veers. Even the forward propagating Corfidi vectors show a southerly component late tonight...and the highest MUCAPE will be over southern Iowa/northern Missouri which will help the overall movement to have a southerly component. Think the MCS will lay down an outflow boundary which will push south into the area on Monday morning...with isolated to widely scattered convection forming on it as it intersects higher CAPE air across eastern Missouri and southwestern Illinois. The 4km NAM nest has the boundary drifting all the way south to near the I-70 corridor by around noon on Monday where it lights up with thunderstorms right around eclipse time at 18Z. All this makes good synoptic sense given the current set up and is very similar to what happened today. Unfortunately this will make eclipse viewing problematic. Convective debris from overnight storms, and new development on the outflow boundary will likely produce considerable cloudiness...but like today there should also be breaks in the clouds, and the clouds may also be partially translucent. Additionally...mesoscale features that are not well represented in the models could change the forecast for the better...or the worse. Unfortunately there's simply no way to precisely predict how cloudy it will be tomorrow at 18Z right now. Carney .LONG TERM... (Monday Night through Next Sunday) Issued at 348 PM CDT Sun Aug 20 2017 (Tuesday) A strong upper level disturbance en route to carving out a longwave TROF over eastern North America will move thru this period. It will be largely coincident with passage of a strong surface cold front. Plenty of moisture to work with, as precipitable water (PW) values thru the column will be over 2 inches and will justify high PoPs, especially north of I-70. Relatively high warm cloud thicknesses at or just above 4km along with the PW values will support a marginal threat for localized heavy rainfall that could lead to an isolated flash flooding event. Time to watch how this evolves and pans out as it will be somewhat dependent on how events the day before play out for specifics and so no plans on any Flood Watch at this time. Lots of clouds and the early onset of decent rain probs for most areas should keep temps in check with low-mid 80s for maxes. (Wednesday - Sunday) NW flow aloft will then prevail Wednesday and Thursday in the wake of passage of the digging shortwave disturbance, with this flow then transitioning some as a weak upper RIDGE slides thru Friday and Saturday. This will all be happening as a strong area of Canadian high pressure dominates the region thru at least Friday and probably into Saturday. While there are some hints from the models at bringing weak, fast moving upper level disturbances thru Wednesday and Thursday, it will need to overcome what should be a dry column in place. With forward speed too much and strength too little, it is unlikely any disturbance of this type will be able to produce sensible wx in our CWA and so opted for a dry forecast. There is also some indication of another disturbance on Saturday, but the track looks to edge our area with marginal moisture and so trended to a dry forecast for this day as well until this can get better resolved. Another shortwave could drop down again on Sunday to help reinvigorate the longwave eastern North American upper TROF but the passage of this feature also looks far enough west at this time to preclude pcpn chances but should set us up to keep the hot temps away as we reach the doorstep of September. Otherwise, the big story here will be a taste of early autumn with daytime max temps around 80 with lo humidity and nighttime mins in the 50s. TES && .AVIATION... (For the 18z TAFs through 18z Monday Afternoon) Issued at 1241 PM CDT Sun Aug 20 2017 Showers and thunderstorms will continue over southeast Missouri into southwest Illinois this afternoon along an outflow boundary left over from last night's thunderstorm complex. Expect VFR conditions outside of thunderstorms this afternoon. Should see storms diminish during the early evening with VFR continuing tonight. Another complex of storms is likely to develop over Iowa tonight and these storms could push another outflow boundary south to near the I-70 corridor tomorrow. This boundary could be another focus for storms late Monday morning into the afternoon much as is occurring today. SPECIFICS FOR KSTL: Expect VFR flight conditions to prevail through the period at Lambert. Thunderstorms south of the terminal along the outflow boundary which passed through this morning should stay south...although I cannot rule out some isolated storms in the vicinity this afternoon. Another complex of storms is likely to develop over Iowa tonight and these storms could push another outflow boundary south to near the I-70 corridor tomorrow. Current thinking is that the boundary will be in the vicinity of the terminal between 17-19Z Monday. Carney && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX