Bill Schintler
EF4
Yet another winter storm will bring a mixture of weather to the area starting Sunday afternoon. Heavy rainfall, thunderstorms, and several inches of snowfall are all likely before the storm pushes east of the area Monday morning. Flooding will also be a concern, especially south of I-80 as temperatures climb to near 60F by late afternoon on Sunday. Below are forecasts for specific locations in eastern IA.
Cedar Rapids:
Rain and isolated thunderstorms will develop after 2 PM on Sunday, and 0.1-0.2 inches of rainfall can be expected, with isolated higher amounts possible in thunderstorms. Precipitation will change to snow at 12 AM on Monday and accumulate to 4.0 inches before ending Monday morning.
Iowa City:
Rain and thunderstorms will develop after 2:30 PM on Sunday, and 0.1-0.2 inches of rainfall can be expected, with isolated higher amounts possible in thunderstorms. Precipitation will change to snow at 1 AM on Monday and accumulate to 3.5 inches before ending Monday morning.
Marengo:
Rain and isolated thunderstorms will develop after 1:30 PM on Sunday, and 0.1-0.2 inches of rainfall can be expected, with isolated higher amounts possible in thunderstorms. Precipitation will change to snow at 12 AM on Monday and accumulate to 4.5 inches before ending Monday morning.
Paris/Coggon:
Rain and isolated thunderstorms will develop after 2 PM on Sunday, and 0.1-0.2 inches of rainfall can be expected, with isolated higher amounts possible in thunderstorms. Precipitation will change to snow at 12 AM on Monday and accumulate to 4.5 inches before ending Monday morning.
Synopsis:
Wow, what a temperature range across the region. Temperatures remained below freezing in NERN IA today where a thick snowpack remained and ERLY SFC flow and a decoupled BL persisted, while stations in the SWRN corner of the state saw the mid-60s with impressive WAA on SWRLY winds. Locations in SWRN NEB even flirted with 80 this afternoon. A SFC WF was located along the IA/MO border ERN IA, and this had pushed N into SWRN IA. In the short term, little additional NWRD movement will occur owing to strong differential heating with ERLY flow and cold ground towards the N. Upstairs, somewhat of a complicated picture was noted. Several pieces of energy were rotating though the NRN stream trough, while a closed H5 low was moving E along the US/Mexico border in the SRN stream. As everything shifts to the E on Sunday evening, the SRN stream wave will become sheared by and absorbed into the positively tilted NRN stream trough while becoming a key player in Iowa late in the period. The GFS initialized best with H85 temperature fields.
Discussion:
Overnight, the ULVL ridge axis currently E of the Rockies will slide to the E, followed by a strengthening 50-60kt SWRLY LLJ over ERN KS. Meanwhile, the WF will continue to strengthen along the IA/MO border in response to strong WAA as noted by an axis of 10m H85 height rises over WRN IA, with the snow fields in ERN IA impeding the NWRD movement of this boundary where the BL remains decoupled. ST and drizzle will develop in response to WAA over the boundary along with SFC convergence and radiational cooling. FZDZ is likely N of I-80 during this period.
During the day Sunday, things get interesting. Increasing isentropic lift along the 310-315K SFCS will cause rain to break out during the mid-day hours. Elevated instability with mid-level lapse rates in excess of 7.5C/km will increase changes for convection during the late afternoon hours. MDLS continue to slow the CF passage and increase the degree of frontogenesis in the SFC-H8 layer. This appears to be related to stronger phasing of the cut off SWRN CONUS low along with mid-level circulations along the frontal zone. The end result will be a prolonged period of WAA and moisture transport. Guidance (GFS, UKMET, and ECMWF) all agree to a high QPF event, with most areas seeing in excess of 1.0 inches storm total QPF, and with the highest amounts SE of a IOW to DBQ line in ERN IA. Furthermore, the latest MDL runs suggest heavier snowfall with 0.5-1.0 inches of liquid QPF following the changeover to snow. Following the passage of the H85 front after midnight, precipitation will rapidly change to snow, and several inches of wet heavy snow is likely after the H85 0C isotherm reaches CID at 11 PM and IOW at 12 AM.
- bill
[FONT="]10:30 PM, 03/01/08[/FONT]
Cedar Rapids:
Rain and isolated thunderstorms will develop after 2 PM on Sunday, and 0.1-0.2 inches of rainfall can be expected, with isolated higher amounts possible in thunderstorms. Precipitation will change to snow at 12 AM on Monday and accumulate to 4.0 inches before ending Monday morning.
Iowa City:
Rain and thunderstorms will develop after 2:30 PM on Sunday, and 0.1-0.2 inches of rainfall can be expected, with isolated higher amounts possible in thunderstorms. Precipitation will change to snow at 1 AM on Monday and accumulate to 3.5 inches before ending Monday morning.
Marengo:
Rain and isolated thunderstorms will develop after 1:30 PM on Sunday, and 0.1-0.2 inches of rainfall can be expected, with isolated higher amounts possible in thunderstorms. Precipitation will change to snow at 12 AM on Monday and accumulate to 4.5 inches before ending Monday morning.
Paris/Coggon:
Rain and isolated thunderstorms will develop after 2 PM on Sunday, and 0.1-0.2 inches of rainfall can be expected, with isolated higher amounts possible in thunderstorms. Precipitation will change to snow at 12 AM on Monday and accumulate to 4.5 inches before ending Monday morning.
Synopsis:
Wow, what a temperature range across the region. Temperatures remained below freezing in NERN IA today where a thick snowpack remained and ERLY SFC flow and a decoupled BL persisted, while stations in the SWRN corner of the state saw the mid-60s with impressive WAA on SWRLY winds. Locations in SWRN NEB even flirted with 80 this afternoon. A SFC WF was located along the IA/MO border ERN IA, and this had pushed N into SWRN IA. In the short term, little additional NWRD movement will occur owing to strong differential heating with ERLY flow and cold ground towards the N. Upstairs, somewhat of a complicated picture was noted. Several pieces of energy were rotating though the NRN stream trough, while a closed H5 low was moving E along the US/Mexico border in the SRN stream. As everything shifts to the E on Sunday evening, the SRN stream wave will become sheared by and absorbed into the positively tilted NRN stream trough while becoming a key player in Iowa late in the period. The GFS initialized best with H85 temperature fields.
Discussion:
Overnight, the ULVL ridge axis currently E of the Rockies will slide to the E, followed by a strengthening 50-60kt SWRLY LLJ over ERN KS. Meanwhile, the WF will continue to strengthen along the IA/MO border in response to strong WAA as noted by an axis of 10m H85 height rises over WRN IA, with the snow fields in ERN IA impeding the NWRD movement of this boundary where the BL remains decoupled. ST and drizzle will develop in response to WAA over the boundary along with SFC convergence and radiational cooling. FZDZ is likely N of I-80 during this period.
During the day Sunday, things get interesting. Increasing isentropic lift along the 310-315K SFCS will cause rain to break out during the mid-day hours. Elevated instability with mid-level lapse rates in excess of 7.5C/km will increase changes for convection during the late afternoon hours. MDLS continue to slow the CF passage and increase the degree of frontogenesis in the SFC-H8 layer. This appears to be related to stronger phasing of the cut off SWRN CONUS low along with mid-level circulations along the frontal zone. The end result will be a prolonged period of WAA and moisture transport. Guidance (GFS, UKMET, and ECMWF) all agree to a high QPF event, with most areas seeing in excess of 1.0 inches storm total QPF, and with the highest amounts SE of a IOW to DBQ line in ERN IA. Furthermore, the latest MDL runs suggest heavier snowfall with 0.5-1.0 inches of liquid QPF following the changeover to snow. Following the passage of the H85 front after midnight, precipitation will rapidly change to snow, and several inches of wet heavy snow is likely after the H85 0C isotherm reaches CID at 11 PM and IOW at 12 AM.
- bill
[FONT="]10:30 PM, 03/01/08[/FONT]
