ICKY, STICKY, AND STORMY...
The long advertised transition to a warm, steamy, and potentially stormy weather pattern is evolving about as expected. The first wave of energy moved east during the day Monday triggered by a mesoscale convective vortex. Heavy rains over an inch were noted in spots. Doppler estimates from the Iowa Flood Center showed the heavier amounts through 4:00pm near I-80. Manlius, Illinois in Bureau County picked up 4 inches and Princeton measured 3. In Iowa, up to 2 inches fell in the northern parts of the Quad City metro, (most notably Eldridge) and 2 inches was indicated just SE of Iowa City.
In the regional perspective you can see the sharp southern cut-off to the rain. That's where a strong warm front was situated over southern Iowa and central Illinois. South of the front, the atmosphere is capped by warm air aloft thwarting thunderstorm development. The position of this boundary will be essential in determining temperature trends and where storm clusters form the next few days.
Additionally, the hi-res goes satellite image clearly shows the warm front at mid-day Monday. South of it, hot sultry conditions prevail with sunshine. To the north, it's much cooler with debris clouds from morning convection.
Positioned on the edge of the strong heat dome, my region now resides in or near the "Ring of Fire", an area we will remain in through at least Thursday. That ensures daily chances of showers and thunderstorms. With available water vapor projected to reach more than 2.5 inches in spots, the atmosphere will be loaded with moisture which you will readily feel..
Any thunderstorm that fire in such an atmosphere could easily produce torrential rains of 1-2 inches an hour. With back-building potential, repeated storms within an MCS cluster could lay down more than that. The potential for localized flash flooding does exist, especially where heavy rains have already occurred. Unfortunately our models have limited ability to specifically define the locations under the gun due to mesocale effects such as outflow boundaries and differential heating. These are highly driven by short term impacts from convection that has yet to develop and thus pattern recognition and short term radar trends will become big players. We'll need to take it day by day.
As you can see, the Weather Prediction Center does have a slight risk of excessive rains in its outlook all the way through Wednesday, July 6th.
The Weather Prediction Center shows this for total precipitation through Thursday.
The National Blend of Models indicates this for the same period.
Severe weather will also remain a threat through at least mid-week. With such high moisture levels and searing heat just to the south, instability is likely to reach extreme levels on the northern edge of the cap which will lay out through my area. The EURO depicts CAPE in the north over 3,500 j/kg Tuesday afternoon.
While damaging winds will be the primary concern, a small but conditional tornado threat exists on an isolated scale with some low level hodograph curvatures.
The Storm Prediction Center has severe weather risks indicated in my area both Tuesday and Wednesday.
An extremely challenging temperature forecast is shaping up for my area the next few days. This is all tied to the position of the warm front which is tough to gauge due to convective outflow. Assuming a large MCS develops somewhere in my area, it will create a cold pool that could force the boundary further south than models are showing. Debris clouds could also limit incoming solar radiation, thus further cooling readings. Again, there is so much uncertainty with these mesoscale features confidence is low on just how hot it will get, especially north of I-80. The south appears to be in a much more favorable position to get into some wicked heat and humidity Tuesday and perhaps again Wednesday.
The EURO show highs in SE Iowa reaching the upper 90s, maybe a couple spots in SE Iowa brushing 100. Low 90s are shown in the far north.
Dew points are robust too with the EURO indicating readings in the low to mid 70s. Big numbers.
The combination of strong heating and moisture would yield heat index values pushing 105 in spots.
My entire area is under a heat advisory Tuesday. Lay low and drink plenty of fluids.
By Friday a deepening east coast trough will turn the upper air flow in from the NW ending the onslaught of heat, humidity, and storms. The coming weekend promises near normal temperatures and minimal humidity. It looks like a dry period as well. Once again, another radical flip in our weather...something we've seen over and over again the past 2 months.
Anyway, I hope you all had a great holiday weekend. Stay cool, calm, and collected on what should be a toasty Tuesday. Roll weather...TS