Cloud shield affecting KCLE associated with two weak lows developing over the Lower Mississippi Valley. No surface precip reported at KCLE on this day.
There is an area of SLW='yes icing' in the same northeasterly quadrant as the MOG PIREP in the radar volume for the polarized IHL. The non-polarized IHL has no SLW, but does have some spotty freezing drizzle at cloud tops that the polarized algorithm does not. ** I believe we are missing Ka-band data, thus missing NIRSS for this case **
Mostly freezing drizzle detected in polarized IHL. Most of the S-band return pattern is west of the radar, so if the two departure null PIREPs on this day were easterly departures they would not have even encountered S-band return.
Most of the S-band return pattern is west of the radar, so if the two departure null PIREPs on this day were easterly departures they would not have even encountered S-band return.
As the 'DRYER' hold pattern (call sign 'DJB') is west-southwest of KCLE, it makes sense that this pilot would call in a 'null' severity icing PIREP as it is evident from the IHL plots that the detected IFI at this time is all north of KCLE. Significant areas of SLW='yes icing' are detected north of KCLE at this PIREP time. The modified SLW algorithm for the non-polarized IHL does a fairly decent job of calling out SLW in the volume, but as is usually the case, the height of SLW is higher than the polarized IHL.
Strengthening 'Nor'easter' surface low over the mid-Atlantic causes northeasterly flow across Lake Erie and the development of a secondary low over southern Ohio. These synoptic dynamics destabilize the lower layers of the atmosphere in northern Ohio and over KCLE. Light snow at the surface begins at 09 UTC and continues through the end of the day.
During the 11UTC hour, many icing PIREPs are reported. The PIREPS generally transition from 'light' severity to 'moderate' as the hour progresses. The polarized IHL sees large swaths of SLW='yes icing'. The non-polarized IHL sees areas of SLW='yes icing' at higher tilts, but almost no areas of positive severity in SLW at the lower tilts. Currently unknown as to why the non-polarized algorithm behaves in this manner. It is also curious to note that IHL has nearly zero freezing drizzle pixels, even near cloud top. Most other IFI cases shown on this page have at least some area of freezing drizzle especially at cloud tops.
Large swaths of SLW='yes icing' persist with the polarized IHL in the radar domain and match with the reported PIREPs. The non-polarized IHL sees areas of SLW='yes icing' at higher tilts, but almost no areas of positive severity in SLW at the lower tilts. Currently unknown as to why the non-polarized algorithm behaves in this manner. ** Need to debug the Freezing Drizzle issue in the non-polarized IHL which occur outside the detectable S-band signal domain. **
Large swaths of SLW='yes icing' persist with the polarized IHL in the radar domain and match with the reported PIREPs.
The PIREP icing severities between 16 and 18Z all seem consistently 'light'. This seems to match a relative minima in percentage of radar volume denoted as SLW='yes icing' in the polarized IHL product. Conversly, the area of freezing drizzle ='yes icing' has expanded compared to previous and future times. There are significant areas of SLW='yes icing' in the modified SLW algorithm for the non-polarized IHL algorithm.
The PIREP icing severities between 16 and 18Z all seem consistently 'light'. This seems to match a relative minima in percentage of radar volume denoted as SLW='yes icing' in the polarized IHL product. Conversly, the area of freezing drizzle ='yes icing' has expanded compared to previous and future times. There are significant areas of SLW='yes icing' in the modified SLW algorithm for the non-polarized IHL algorithm.
As the Nor'easter pushes off the Atlantic coast, a Lake Effect snow event for KCLE sets up and persists throughout this day.
Lake Effect snow bands in the KCLE domain are seen to be oriented with the mean flow from northwest to southeast. The polarized IHL places a significant volume of SLW='yes icing' along the highest reflectivity areas of LE at all tilt angles. The non-polarized SLW algorithm completely misses the embedded mixed phase icing. In fact the SLW area is nearly the perfect inverse of the high reflecitivity snowband areas. As with the onset of icing on the previous day, nearly zero freezing drizzle volume is detected at this time ( an interesting trend to keep an eye on!). The LE band existance is well represented in the PING plot.
There indeed is no icing in the northwest quadrant at the time of this null icing severity PIREP as the LE band has shifted east of KCLE. The bands eastward translation is clearly evident in the NEXRAD reflectivity images. IHL nonetheless detects significant SLW='yes icing' in the band. The same inverse relation with the non-polarized SLW algorithm exists at this time.
The bands eastward translation is clearly evident in the NEXRAD reflectivity images. IHL nonetheless detects significant SLW='yes icing' in the band. The same inverse relation with the non-polarized SLW algorithm exists at this time.