Tornadoes in Northern Illinois
It was a busy severe weather day yesterday across the middle part of the country. Nearly 350 reports of hail, high wind and tornadoes came in; 16 of which were PRELIMINARY tornado reports. Take a look at this large tornado from near Rochelle, IL!
(Image Courtesy: NWS Chicago via Scott Prader)
Based on reports from trained storm spotters and chasers as well as radar and environmental evidence, there were at the very least two tornadoes, but likely more across North Central Illinois on April 9th.
At least two long-lived supercell thunderstorms produced these tornadoes, or family of tornadoes, across North Central Illinois.
Communities impacted based on reports include Cherry Valley, Flagg Center, Fairdale, and Kirkland.
Three damage survey teams are in the field today surveying. This process may need to go into Saturday.
Another brief tornado occurred earlier in the afternoon north of Peoria.
The atmosphere was ripe for severe weather due to highly anomalous moisture and instability for early April across the region. A strong low pressure system advanced into this favorable air mass helping to trigger these potent storms.
The potential for severe weather was mentioned in NWS forecast graphics and products as early as Saturday, April 4th.
Tornado on Radar
The loop below is from the National Weather Service out of Chicago, IL – note the fairly robust line of storms that moves into the northern part of IL by the end of the loop; at one point, you can see a classic “Hook Echo” just south of Rockford… this was one of the tornadoes that passed just NW of Rochelle, IL (pictured above).
Thursday Severe Recap
According to NOAA’s SPC, there were nearly 350 severe weather reports across the nation yesterday; 16 of those were PRELIMINARY tornado reports!
National Weather Outlook
Our severe weather threat has ended across the mid-section of the nation today. However, the same front will kick out more strong/severe thunderstorms across the eastern/southern part of the country today. Another impulse of energy may ignite a few strong/severe storms this weekend.
Severe Threat Friday
…MID-ATLANTIC INTO CAROLINAS THIS AFTERNOON INTO EVENING…
THE EWD PROGRESSION OF THE PRE-FRONTAL CONVECTIVE BAND PRESENT FROM
THE UPPER-OH VALLEY INTO CUMBERLAND PLATEAU AS OF 12Z IS FASTER THAN
MOST MODEL GUIDANCE WITH EXTRAPOLATION PLACING THE REMNANTS OF THESE
STORMS EAST OF THE BLUE RIDGE BY LATE MORNING. AHEAD OF THIS
ACTIVITY…THE SRN EXTENSION OF A SWLY LLJ WILL MAINTAIN THE
POLEWARD FLUX OF HEAT AND MOISTURE E OF THE APPALACHIANS WITH
AFTERNOON MLCAPE APPROACHING 500-1000 J/JG ALONG AND TO THE SOUTH OF
THE WARM FRONT. THIS AIR MASS DESTABILIZATION COUPLED WITH
CONVERGENCE ALONG THE SYNOPTIC FRONTS AND CONVECTIVE OUTFLOW
BOUNDARIES IS EXPECTED TO FOSTER THE DEVELOPMENT AND/OR
RE-INTENSIFICATION OF STORMS BY EARLY AFTERNOON OVER THE PIEDMONT.
A LARGELY UNIDIRECTIONAL WIND FIELD WITH DEEP-LAYER SHEAR RANGING
FROM 40-50 KT OVER THE DELMARVA TO 30-35 KT OVER THE CAROLINAS WILL
BE SUPPORTIVE ORGANIZED STORM MODES…INCLUDING SUPERCELLS AND
BOWING STRUCTURES AS ACTIVITY PROGRESSES EWD INTO THE COASTAL PLAIN.
DAMAGING STRAIGHT LINE WINDS AND MARGINALLY SEVERE HAIL WILL BE THE
PRIMARY HAZARDS WITH THESE STORMS. THE GREATEST RISK FOR A BRIEF
TORNADO OR TWO APPEARS TO BE IN THE VICINITY OF THE WARM FRONT OVER
VA…PERHAPS INTO PARTS OF MD WHERE LOW-LEVEL SHEAR IS ENHANCED.
…GULF COAST STATES INTO GA THIS AFTERNOON INTO EVENING…
12Z OBSERVED SOUNDINGS SAMPLED A MOIST ENVIRONMENT TO THE SOUTH OF
THE ONGOING STORMS WITH BOUNDARY-LAYER DEWPOINTS IN THE MID TO UPPER
60S AND LOWEST-100-MB MEAN-MIXING RATIOS OF 13-15 G/KG. THIS
MOISTURE WILL OFFSET THE TEMPERING OF DAYTIME HEATING BY EXISTING
CLOUDS TO SUPPORT POCKETS OF MODERATE AFTERNOON INSTABILITY
CHARACTERIZED BY MLCAPE OF 1000-2000 J/KG. ACTIVE COLD POOLS
ASSOCIATED WITH MORNING STORMS WILL COMBINE WITH THE ARRIVAL OF THE
SURFACE COLD FRONT TO SUPPORT AN INCREASE IN STORMS BY AFTERNOON
AMIDST A KINEMATIC ENVIRONMENT FEATURING A LARGELY UNIDIRECTIONAL
WIND FIELD AND AROUND 30 KT OF DEEP-LAYER SHEAR. THIS SETUP SHOULD
FAVOR MULTICELL CLUSTERS AND LINE SEGMENTS CAPABLE OF LOCALLY
DAMAGING WINDS AND PERHAPS MARGINALLY SEVERE HAIL INTO THIS
…SOUTH TX THIS AFTERNOON AND EVENING…
CLUSTERS OF TSTMS ARE ONGOING AS OF 12Z OVER THE EDWARDS PLATEAU
INTO BRUSH COUNTRY INVOF THE SWD-MOVING COLD FRONT…PERHAPS IN
ASSOCIATION WITH A WEAK PERTURBATION APPROACHING THE LOWER RIO
GRANDE VALLEY FROM THE W. WHILE MID-LEVEL LAPSE RATES WERE NOT
PARTICULARLY STEEP ON THE 12Z RAOBS…MOIST BOUNDARY-LAYER
CONDITIONS AND DAYTIME HEATING TO THE SOUTH OF THIS EARLY-DAY
ACTIVITY SHOULD SUPPORT MODERATE AFTERNOON INSTABILITY…AND THE
POTENTIAL FOR A FEW STRONG TO SEVERE STORMS LATER TODAY.
…SOUTHWEST TX THIS AFTERNOON AND EVENING…
POST-FRONTAL WINDS WILL BECOME ELY TODAY…ALLOWING FOR THE
ADVECTION OF AN INCREASINGLY MOIST BOUNDARY LAYER FROM THE EDWARDS
PLATEAU. HEATING ALONG THE HIGH TERRAIN WILL COMBINE WITH WEAK
DISTURBANCES EMBEDDED WITH THE SUB-TROPICAL AIR STREAM TO FOSTER
ISOLATED AFTERNOON TSTMS. STEEPENING MID-LEVEL LAPSE RATES AND
VERTICALLY VEERING WIND PROFILE WITH 40-45 KT OF DEEP-LAYER SHEAR
WILL BE SUPPORTIVE OF ROTATING STORMS WITH A RISK FOR MAINLY HAIL.
Severe Threat Saturday
…ERN CO INTO WRN KS…
DEWPOINTS INTO THE 40S F WILL RETURN NWD INTO THE LEE-TROUGHING ZONE
FROM EXTREME ERN CO INTO WRN KS BY 00Z. GIVEN 500 MB TEMPERATURES ON
THE ORDER OF -16 TO -18 C…THIS WILL BE SUFFICIENT IN COMBINATION
WITH DAYTIME HEATING TO YIELD AROUND 1000 J/KG MUCAPE. HEATING WILL
ERODE CAPPING BY LATE AFTERNOON AND CONVERGENCE WITHIN THE TROUGH
SHOULD BE ENOUGH TO INITIATE AT LEAST ISOLATED STRONG THUNDERSTORMS.
WHILE MOISTURE WILL BE LIMITED…VEERING WINDS WITH HEIGHT WILL
FAVOR CELLULAR STORM MODE…PERHAPS A HIGH-BASED SUPERCELL OR
TWO…CAPABLE OF LARGE HAIL. STORMS MAY EVENTUALLY MERGE INTO A
SMALL MCS…CONTINUING EWD ACROSS KS AND SUPPORTED BY A STRONG SLY
LOW-LEVEL JET. HOWEVER…SEVERE WEATHER IS NOT EXPECTED WITH THIS
Severe Threat Sunday
…SERN KS…MO…NRN OK…
STORMS ARE EXPECTED TO BE ONGOING EARLY SUNDAY FROM ERN KS INTO MO
IN ASSOCIATION WITH AFOREMENTIONED LEADING DISTURBANCE AND A 40 KT
SWLY LOW-LEVEL JET. WITH COOL PROFILES ALOFT AND FAVORABLE WIND
PROFILES…SOME OF THESE STORMS COULD PRODUCE HAIL.
LATER IN THE DAY IN THE WAKE OF THE EARLY ACTIVITY…HEATING AHEAD
OF THE WEAK/TRAILING FRONT WILL BE A FOCUS FOR DEVELOPMENT NEAR AND
SHORTLY AFTER 00Z DESPITE SOME CAPPING INVERSION NEAR 700 MB. AMPLE
DEEP-LAYER SHEAR AND STEEP LAPSE RATES ALOFT WILL PROMOTE VIGOROUS
UPDRAFTS AND HAIL PRODUCTION. HOWEVER…THE EVENTUAL UNDERCUTTING
FRONT MAY CONSOLIDATE THE STORMS INTO A SWD-MOVING MCS WITH SPORADIC
WIND DAMAGE POTENTIAL. PORTIONS OF THIS AREA MAY BE UPGRADED TO A
SLIGHT RISK IN LATER OUTLOOKS WHEN CONFIDENCE INCREASES.
INSTABILITY WILL BUILD DURING THE DAY PRECEDING THE ARRIVAL OF THE
UPPER TROUGH. STORMS ARE EXPECTED TO FORM OVER NRN MX INTO SWRN
TX…AND DEVELOP EWD ACROSS THE RIO GRANDE. INCREASING MEAN WIND
FIELDS ALOFT AS WELL AS SOME LOW-LEVEL TURNING WITH HEIGHT SUGGEST
PERHAPS AN MCS AND MARGINAL WIND THREAT SUNDAY NIGHT ACROSS SRN TX.
According to NOAA’s HPC, the 5 day rainfall forecast suggests another round of heavy rainfall across the south-central part of the country. The forecasts suggests an additional 1″ to 3″ through early next week.
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