Another squall line Monday morning, winter’s not over

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1. I expect Saturday to be mostly sunny with highs in the 50’s as once again week southerly flow commences.

2. this brings a warm front through Sunday which will lead to overrunning precipitation in the form of scattered light rain showers. Lows should in the 40’s with highs once again in the 50’s. cloudcover will keep lows up and highs lower in the day.

3. We enter the warm sector sunday night as once again another squall line develops to our west, this time the entire region is in the warm sector meaning we all get the line. Right now I like the cmc’s timing around 7 am in BWG and late morning in LEX. Not great for severe storms and is a blend of the NAM and GFS on timing and accounts for both model biases. Once again several factors are favorable for severe weather, there appears more instability this go around and plenty of shear and moisture once again.

The NWS LMK office had a good meteorological discussion of this. I will translate some of meteorology talk.

THE MAIN EVENT SHOULD OCCUR SUNDAY NIGHT INTO LATE MONDAY MORNING AS
STRONG LOW PRESSURE MOVES THROUGH THE LOWER GREAT LAKES AND DRAGS A
COLD FRONT THROUGH THE AREA. AHEAD OF THIS FRONT…BROAD
SOUTHWESTERLY FLOW ALOFT COMBINED WITH LOW LEVEL MOISTURE ADVECTION
WILL COMBINE TO PROVIDE PLENTY OF DEEP MOISTURE FOR THE FRONT TO
WORK WITH.

( already talked about above)

STRONG DYNAMICS WILL BE IN PLACE WITH LEFT EXIT REGION OF
A 120 KNOT UPPER LEVEL JET ENTERING OUR AREA. LOW LEVEL JET AROUND
70 KNOTS

The jet stream strength and amplitude are directly related to storm strength. A jet streak is a region of faster winds within the overall storm, the left exit region is a region for convergence which is good for thunderstorm development. the overall jet streak also tends to increase the speed of storms which promotes a wind threat. the LLJ does the same but is associated with low pressure systems and connects the gulf with warmth and moisture. thus the temp rise thursday night ahead of the squall line. A LLJ near 70 knots supports severe weather.

COMBINED WITH SLIGHTLY BACKED SURFACE WINDS WILL CREATE
LARGE AND LOOPING LOW LEVEL HODOGRAPHS.

This is more a shear analysis. hodogrpahs are a 2D figure of wind direction and speed with height. the hodographs I’ve looked at for this event suggest more of a squall line and are not favorable for supercells.

AS HAS BEEN TYPICAL…
SURFACE BASED INSTABILITY WILL BE LIMITED WHICH WILL LIMIT THE
POTENTIAL FOR A MORE WIDESPREAD WIND AND TORNADO OUTBREAK. THAT
BEING SAID…DO EXPECT TO SEE SOME SEVERE WEATHER AND WOULD NOT BE
SURPRISED TO SEE OUR AREA OUTLOOKED OVER THE NEXT DAY OR TWO. EXPECT
A LINEARLY FORCED CONVECTIVE SYSTEM TO DEVELOP AND MOVE THROUGH THE
REGION BETWEEN MIDNIGHT AND LATE MORNING MONDAY WITH POTENTIAL FOR
LEWPS STRUCTURE/BOWING SEGMENTS.

shear is present, instabilty marginal but slightly better,

LEANED ON THE GFS ENSEMBLE MEAN/GFS/GEM FASTER SOLUTION WITH THIS
SYSTEM AS IT HAS THE MOST SUPPORT. HOWEVER HAVE TO MENTION THE
SLIGHTLY SLOWER SCENARIO OFFERED BY ECMWF/NAM12 THIS WOULD BRING THE
FRONT THROUGH THE AREA LATER ON MONDAY AND WOULD ALLOW FOR THE
POTENTIAL FOR MORE INSTABILITY AHEAD OF IT. THIS SOLUTION IS NOT
PREFERRED DUE TO POOR NAM PERFORMANCE THAT FAR OUT AND ECMWF
TENDENCY TO HOLD ONTO SOUTHWEST ENERGY TOO LONG.

Agree with it for the most part. Another high impact squall line Monday morning.

Now onto winter’s not over

just one figure. right now the ensemble mean of the GFS and CMC are pushing cold into the northern plains for days 10-15 in the first part of March. In recent weeks this has been held at bay. Not so fast this time. I still think one blast of winter is coming between March 5th and 12th. The NAO is going negative which shifts the storm track east and the stratospheric signal continues to point to a nice surge of cold coming into the central plains during this timeframe. Of interest should be a system around the 8th tracking through the southern plains and going east.

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