oldlogin Posted January 11, 2013 Share Posted January 11, 2013 Mike Ryans afternoon AFD from IND ISSUED AT 340 PM EST FRI JAN 11 2013 FORECAST CHALLENGES ABOUND IN THE SHORT TERM AS LOW PRESSURE WAVE RIDES ALONG INTO THE OHIO VALLEY ALONG A FRONTAL BOUNDARY...WITH RAIN SPREADING BACK INTO THE REGION LATE SATURDAY AND SATURDAY NIGHT. INCREASING VARIANCE IN MODEL SOLUTIONS WITH REGARDS TO HOW QUICKLY THE COLDER AIR ADVECTS INTO THE FORECAST AREA LATE SATURDAY NIGHT INTO SUNDAY AND THIS IS CAUSING SOME QUESTION MARKS WITH RESPECT TO PRECIP TYPE AND DURATION ON THE BACK SIDE OF THE PRECIP SHIELD. WILL ADDRESS IN GREATER DETAIL BELOW. STRONG LOW PRESSURE WILL MOVE INTO THE UPPER MISSISSIPPI VALLEY BY SATURDAY MORNING WITH A TRAILING COLD FRONT EXTENDING SOUTH INTO THE SOUTHERN PLAINS. AS THE FRONT TRACKS EAST SATURDAY...IT WILL COME INTO CONTACT WITH GULF MOISTURE BEING PULLED NORTH INTO THE OHIO VALLEY BY THE AFTERNOON. A LOW PRESSURE WAVE DEVELOPING ALONG THE BOUNDARY SATURDAY WILL LIFT OUT OF THE TEXAS AND MOVE ALONG THE BOUNDARY INTO THE REGION BY SATURDAY NIGHT. THIS WILL BRING ANOTHER ROUND OF WIDESPREAD RAINFALL...LOCALLY HEAVY AT TIMES...ALONG WITH EMBEDDED THUNDERSTORMS BEGINNING LATE SATURDAY AFTERNOON AND PERSISTING INTO SATURDAY NIGHT. MODEL GUIDANCE TODAY HAS SHIFTED THE AXIS OF HEAVIEST RAINFALL FURTHER NORTH AND WEST FROM PREVIOUS RUNS...WITH IT NOW ALIGNED ACROSS THE SOUTHEAST HALF OF THE FORECAST AREA SATURDAY NIGHT AS A STRONG LOW LEVEL JET MOVES THROUGH THE OHIO VALLEY. A NUMBER OF SIGNS POINT TO THE POTENTIAL FOR A 6-8 HOUR PERIOD WITH HEAVY RAIN AND EMBEDDED CONVECTION SATURDAY NIGHT. LOW LEVEL FORCING WILL COMBINE WITH A CONTINUED SURGE OF DEEP MOISTURE WITH PRECIP WATER VALUES AT 1.50 TO 1.60 INCHES...WHICH IS ROUGHLY 400% OF NORMAL FOR THIS TIME OF YEAR. IN THE UPPER LEVELS...EXPECT RAINFALL TO BE ENHANCED DUE TO INCREASING DIFFLUENCE ALOFT AND A STRONG SOUTHWESTERLY UPPER JETLET WITH MAX SPEEDS AT 160-170MPH OVER THE GREAT LAKES BY 06Z SUNDAY...PLACING CENTRAL INDIANA WITHIN THE RIGHT REAR QUAD OF THE JET MAX. FURTHERMORE...STRONG BAROCLINIC ZONE WILL SET UP ALONG THE FRONTAL BOUNDARY AND WILL LIKELY FURTHER ENHANCE RAINFALL COVERAGE AND INTENSITY AT LEAST FOR SOME TIME SATURDAY NIGHT. WITH ALL OF THESE FACTORS IN PLAY...WILL BE CONTINUING WITH CATEGORICAL POPS OVER THE ENTIRE FORECAST AREA WITH HEAVIEST RAINFALL LIKELY TO BE FOCUSED ALONG AND SOUTH OF A KHUF-KIND-KMIE LINE WHERE DEEPEST MOISTURE WILL ALIGN WITH STRONGEST LIFT. CONFIDENCE IS HIGH IN 1 TO 2 INCHES FALLING ACROSS THE ENTIRE FORECAST AREA BEGINNING SATURDAY AFTERNOON THROUGH SUNDAY...WITH HIGHEST AMOUNTS AGAIN SOUTH OF A KHUF-KIND-KMIE LINE WHERE LOCALLY HIGHER AMOUNTS ABOVE 2 INCHES CANNOT BE RULED OUT. HEAVIEST PRECIPITATION WILL BE DEPARTING THE FORECAST AREA BY DAYBREAK SUNDAY AS THE BOUNDARY SHIFTS TO NEAR THE OHIO RIVER AND LOW PRESSURE MOVES INTO THE EASTERN GREAT LAKES. AS MENTIONED ABOVE...TIMING OF THE ARRIVAL OF COLDER AIR INTO THE REGION BEHIND THE FRONT IS LEADING TO A MORE CHALLENGING PRECIP TYPE FORECAST BEGINNING LATE SATURDAY NIGHT IN THE NORTHERN WABASH VALLEY AND STEADILY EXPANDING SOUTHEAST THROUGH THE DAY SUNDAY. NAM IS MOST AGGRESSIVE WITH COLDER AIR...MORESO THAN MODEL CONSENSUS AND LIKELY DUE TO THE FACT THAT IT APPEARS TO BE BREAKING DOWN THE SOUTHEAST UPPER RIDGE MORE QUICKLY THAN OTHER MODELS. WITH SUCH A HIGHLY AMPLIFIED UPPER LEVEL PATTERN OVER THE COUNTRY...THE SLOWER SOLUTION PRESENTED BY THE MODEL CONSENSUS IS PREFERRED. MORE SPECIFICALLY... HAVE TRENDED CLOSER TO A ECMWF/OP GFS SOLUTION WHICH IS SLOWER WITH THE COLD AIR INTRUSION BUT STILL SUGGESTING SURFACE TEMPS AT OR JUST BELOW FREEZING IN THE NORTHERN WABASH VALLEY BY 12Z SUNDAY. HAVE INTRODUCED A CHANCE FOR SLEET AND FREEZING RAIN TO GO ALONG WITH RAIN POTENTIAL IN THE FAR NORTHWEST BETWEEN 06-12Z SUNDAY. MODEL SOUNDINGS SHOWING A FAIRLY DEEP LAYER ABOVE FREEZING ON SUNDAY AS THE COLDER NEAR SURFACE AIR EXPANDS ACROSS THE FORECAST AREA. WILL CONTINUE TO CARRY A FREEZING RAIN/SLEET MIX GENERALLY NORTHWEST OF INDIANAPOLIS SUNDAY MORNING...GRADUALLY TRANSITIONING TO MORE OF A SLEET/SNOW MIX SUNDAY AFTERNOON AS SUPPORTED BY SOUNDINGS. AS ICE CRYSTAL GENERATION IS LOST WITH DRIER AIR ALOFT...PRECIP MAY EVEN SWITCH TO FREEZING DRIZZLE FOR A PERIOD OF TIME OVER NORTHWEST COUNTIES. TO THE SOUTHEAST OF INDIANAPOLIS...APPEARS LOWER LEVELS WILL REMAIN WARM ENOUGH TO SUPPORT ALL RAIN FOR MOST IF NOT ALL OF THE DAY SUNDAY. ANY LINGERING PRECIP WILL BE LIGHT SUNDAY NIGHT AS THE FRONT SHIFTS FURTHER AWAY...EVENTUALLY TRANSITIONING TO ALL SNOW. AT THIS POINT...A SMALL ACCUMULATION OF FREEZING RAIN/SLEET/ SNOW IS POSSIBLE OVER WESTERN COUNTIES ON SUNDAY...BUT DETAILS REMAIN RATHER MURKY AND HIGHLY DEPENDENT ON HOW QUICKLY THE COLDER AIR ARRIVES AS DEEPER MOISTURE DEPARTS. WILL CONTINUE TO MONITOR CLOSELY INTO THE WEEKEND. NOW APPEARS THAT THE FRONT WILL MOVE FAR ENOUGH AWAY FROM THE REGION TO GO WITH A DRY FORECAST FOR MONDAY. HIGH PRESSURE BUILDING INTO CENTRAL INDIANA SHOULD ENABLE DECREASING CLOUDS. TEMPS...ANOTHER WARM DAY EXPECTED SATURDAY WITH MOIST SOUTHERLY FLOW AHEAD OF THE FRONT. LEANED TOWARDS COOLER MAVMOS GUIDANCE WHICH SUPPORTED LOW LEVEL THERMALS. TEMPS BECOME MUCH TRICKIER SATURDAY NIGHT AND SUNDAY AS THE FRONT MOVES INTO THEN CROSSES THE FORECAST AREA. TEMPS WILL FALL WITH THE PASSAGE OF THE FRONT LATE SATURDAY NIGHT...THEN CONTINUE TO FALL SUNDAY AS SHARP COLD ADVECTION TAKES HOLD. ONCE AGAIN HAVE MATCHED SATURDAY NIGHT LOWS AND SUNDAY HIGHS AT 12Z SUNDAY...WITH TEMPS FALLING INTO THE MID 20S AND LOWER 30S BY SUNDAY EVENING. NEAR MOS GUIDANCE FOR THE REMAINDER OF THE SHORT TERM AS TEMPS RETURN TO NEAR NORMAL VALUES. Link to comment Share on other sites More sharing options...
Chicago Storm Posted January 11, 2013 Share Posted January 11, 2013 The end may be near, you guys. Link to comment Share on other sites More sharing options...
IWXwx Posted January 11, 2013 Share Posted January 11, 2013 IWX apparently isn't sure of temperature profiles, so they covered all of their bases. A little something for everyone here: Sunday Freezing rain and sleet likely before 10am, then a chance of rain, freezing rain, and sleet between 10am and 1pm, then a chance of snow, freezing rain, and sleet after 1pm. Mostly cloudy, with a high near 36. Northwest wind around 10 mph. Chance of precipitation is 60%. Little or no ice accumulation expected. New snow and sleet accumulation of less than a half inch possible. Not much impact here, but it will be fun to watch. Link to comment Share on other sites More sharing options...
Thunder Road Posted January 11, 2013 Share Posted January 11, 2013 Point & click for VPZ: New ice accumulation of 0.3 to 0.5 of an inch possible. I know it's just a P&C, but it seems awfully bullish to me. With temps so warm today and tomorrow, we would need some very impressive low-level CAA to get the surface well enough below freezing down here. If 0.3" of ice was actually going to verify, we'd have a WWA or perhaps even an Ice Storm Warning out with the afternoon package. Link to comment Share on other sites More sharing options...
Geos Posted January 11, 2013 Share Posted January 11, 2013 I have sleet and snow going over to snow after midnight. Beast: where do you see 3-5" here? Link to comment Share on other sites More sharing options...
A-L-E-K Posted January 11, 2013 Share Posted January 11, 2013 .4 of ice in my point...agree with thunder road, sounds bullish. Link to comment Share on other sites More sharing options...
wisconsinwx Posted January 11, 2013 Share Posted January 11, 2013 http://www.americanwx.com/bb/index.php/topic/13868-feb-26-mar-1st-winter-storm-potential/page-9 This illustrates my concern; the event featured a major NW shift 24-36 hours from the event with all the major models. Look at $Man's post in particular, QPF numbers and all. Milwaukee got basically nothing, and the Chicago area got some freezing rain and sleet, which is more in line with what they expected. Link to comment Share on other sites More sharing options...
Hoosier Posted January 11, 2013 Author Share Posted January 11, 2013 Point & click for VPZ: I know it's just a P&C, but it seems awfully bullish to me. With temps so warm today and tomorrow, we would need some very impressive low-level CAA to get the surface well enough below freezing down here. If 0.3" of ice was actually going to verify, we'd have a WWA or perhaps even an Ice Storm Warning out with the afternoon package. Look upstream...there are some pretty nice temp drops behind the front. I think accretion on the ground could be hurt a little initially but it was cold before this warm spell so it might not be a huge negating factor. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted January 11, 2013 Share Posted January 11, 2013 http://www.americanwx.com/bb/index.php/topic/13868-feb-26-mar-1st-winter-storm-potential/page-9 This illustrates my concern; the event featured a major NW shift 24-36 hours from the event with all the major models. Look at $Man's post in particular, QPF numbers and all. Milwaukee got basically nothing, and the Chicago area got some freezing rain and sleet, which is more in line with what they expected. Unless the setup is the same no point in bringing it up. Link to comment Share on other sites More sharing options...
Geos Posted January 11, 2013 Share Posted January 11, 2013 RGEM. Close call here. Looking better and better for Cyclone. Link to comment Share on other sites More sharing options...
BowMeHunter Posted January 11, 2013 Share Posted January 11, 2013 http://www.americanwx.com/bb/index.php/topic/13868-feb-26-mar-1st-winter-storm-potential/page-9 This illustrates my concern; the event featured a major NW shift 24-36 hours from the event with all the major models. Look at $Man's post in particular, QPF numbers and all. Milwaukee got basically nothing, and the Chicago area got some freezing rain and sleet, which is more in line with what they expected. 2011 lulz Link to comment Share on other sites More sharing options...
wisconsinwx Posted January 11, 2013 Share Posted January 11, 2013 Unless the setup is the same no point in bringing it up. It's not the same but it is similar in that it was a system that was supposed to be progressive and not give much snow anywhere; then all of a sudden the models came in hot, but ultimately it was fool's gold. You're right, it was preceded by a light snow event the night before, and was much colder prior to the storm, so it's not that similar, but the sudden shift was similar and even closer to the event. Link to comment Share on other sites More sharing options...
Thunder Road Posted January 11, 2013 Share Posted January 11, 2013 Look upstream...there are some pretty nice temp drops behind the front. I think accretion on the ground could be hurt a little initially but it was cold before this warm spell so it might not be a huge negating factor. I'm thinking more about the ground itself than 2 m temps. Is it actually possible that the amount of moisture in the ground (I don't know if LAF got hit as hard last night, but we're saturated here) can limit its ability to cool? I know because of latent heat processes, the ground's ability to warm is affected... Link to comment Share on other sites More sharing options...
Thunder Road Posted January 11, 2013 Share Posted January 11, 2013 Quick note on the RGEM, for three events in late December it verified too cold/too far south with the RA/SN line in the Mid-Atlantic. Not sure if that's a regional thing or if the RGEM actually has a cold bias everywhere. This is also a different set-up than those were, since they involved at least a little bit of CAD, but it's worth noting and paying attention too. Link to comment Share on other sites More sharing options...
wisconsinwx Posted January 11, 2013 Share Posted January 11, 2013 Quick note on the RGEM, for three events in late December it verified too cold/too far south with the RA/SN line in the Mid-Atlantic. Not sure if that's a regional thing or if the RGEM actually has a cold bias everywhere. This is also a different set-up than those were, since they involved at least a little bit of CAD, but it's worth noting and paying attention too. Wouldn't be surprised if it has a cold bias on a regular basis with similar systems. Looks quite generous for sure, though given timing it could happen. Link to comment Share on other sites More sharing options...
BeastFromTheEast Posted January 11, 2013 Share Posted January 11, 2013 I have sleet and snow going over to snow after midnight. Beast: where do you see 3-5" here? Your point and click had 3-5" at the time I posted that but it changed to 1-3" now.. Link to comment Share on other sites More sharing options...
Geos Posted January 11, 2013 Share Posted January 11, 2013 Your point and click had 3-5" at the time I posted that but it changed to 1-3" now.. Some rookie Met probably put up the NAM totals and then someone else changed it! haha Link to comment Share on other sites More sharing options...
Thundersnow12 Posted January 11, 2013 Share Posted January 11, 2013 15z SREF, has moved a bit NW each of the last two runs with higher amounts too. Link to comment Share on other sites More sharing options...
cyclone77 Posted January 11, 2013 Share Posted January 11, 2013 Even here out in western IL the Euro shows some mixing initially. Still delivers a few inches of wet snow though. What a change from this time yesterday. Link to comment Share on other sites More sharing options...
wisconsinwx Posted January 12, 2013 Share Posted January 12, 2013 15z SREF, has moved a bit NW each of the last two runs with higher amounts too. SREF_SNOWFALL_MEAN12HR_f042.gif The 18z GFS Ensembles if anything took a step SE and drier for most vs 12z, so more in line with the NAM, with the Euro, SREF, GEM and UKMET the NW camp. I would typically side with the NW camp because the Euro and UKMET combo should be a good sign, but the local mets are going 1-2" at best, and I think it is a concern that the GFS Ensembles are not very bullish. Any word about the Euro Ensembles? Probably SE of the OP would be my guess, but how much? Link to comment Share on other sites More sharing options...
TugHillMatt Posted January 12, 2013 Share Posted January 12, 2013 The 18z GFS Ensembles if anything took a step SE and drier for most vs 12z, so more in line with the NAM, with the Euro, SREF, GEM and UKMET the NW camp. I would typically side with the NW camp because the Euro and UKMET combo should be a good sign, but the local mets are going 1-2" at best, and I think it is a concern that the GFS Ensembles are not very bullish. Any word about the Euro Ensembles? Probably SE of the OP would be my guess, but how much? Do you have the link for the ensembles? I can not believe.we went from being missed to the southeast to now getting ice with MAYBE snow here. Just can't win... Link to comment Share on other sites More sharing options...
Geos Posted January 12, 2013 Share Posted January 12, 2013 CMC has some heavy snow returns in the 12z run. http://collaboration.cmc.ec.gc.ca/cmc/cmdn/pcpn_type/pcpn_type_gem_reg.html'>http://collaboration.cmc.ec.gc.ca/cmc/cmdn/pcpn_type/pcpn_type_gem_reg.html Link to comment Share on other sites More sharing options...
A-L-E-K Posted January 12, 2013 Share Posted January 12, 2013 The baroclinic zone is pretty impressive and the airmass to the south has been open to the gulf for quite some time. The wetter model runs make some sense, just how much moisture gets pull back into the cold sector is debatable but i'd lean wetter. Warm air is still going to be an issue. Link to comment Share on other sites More sharing options...
Harry Posted January 12, 2013 Share Posted January 12, 2013 Do you have the link for the ensembles? I can not believe.we went from being missed to the southeast to now getting ice with MAYBE snow here. Just can't win... Dude you will be fine. You are sitting pretty. It is down this way that looks to get screwed once again with the rain/ice crap. Oh and the 12z euro ens were even more bullish then the 00z were. Surface low to Toledo/near just east of Detroit. The .25+ line is now almost to the MS river and cuts through Madison on nne/ne to Sheboygan... Link to comment Share on other sites More sharing options...
Thundersnow12 Posted January 12, 2013 Share Posted January 12, 2013 Dude you will be fine. You are sitting pretty. It is down this way that looks to get screwed once again with the rain/ice crap. Oh and the 12z euro ens were even more bullish then the 00z were. Surface low to Toledo/near just east of Detroit. The .25+ line is now almost to the MS river and cuts through Madison on nne/ne to Sheboygan... How were they for this area? Mixed bag? Link to comment Share on other sites More sharing options...
Harry Posted January 12, 2013 Share Posted January 12, 2013 How were they for this area? Mixed bag? Draw a line from say Chicago to Grand Rapids and all along/se of that line will have mixing concerns. Less of a concern the further nw of that line you go. Granted i am unsure of how much/if any influence the lake will have? You know how that goes. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted January 12, 2013 Share Posted January 12, 2013 0z NAM looks pretty close to the 18z run through 27hr, a tad more cold sector QPF and a bit further NW but 0 deg 850mb isotherm in about the same spot, little more precip further north into central IL. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted January 12, 2013 Share Posted January 12, 2013 Little less frozen precip now with 0 deg 850mb isotherm not as far east at 30hr. Link to comment Share on other sites More sharing options...
Thundersnow12 Posted January 12, 2013 Share Posted January 12, 2013 Warm layer around 750mb screws my area on the 0z NAM. Only would know it looking at soundings Link to comment Share on other sites More sharing options...
Geos Posted January 12, 2013 Share Posted January 12, 2013 Draw a line from say Chicago to Grand Rapids and all along/se of that line will have mixing concerns. Less of a concern the further nw of that line you go. Granted i am unsure of how much/if any influence the lake will have? You know how that goes. Winds will be offshore, so no lake influence on this side of the lake. LM temperatures: http://www.coastwatch.msu.edu/michigan/7day/m4/Jan10/2013_Jan10_228EDT.gif Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.