Severe Weather Risk - Thu 4/30 & Fri 5/1

[venture]

Major concerns today are storms producing large hail. No specific location is better than another today. So many boundaries are laying all over the place, any spot could become the focal point for today. Short term models show a general coverage in precip today, but not of any really heavy amounts. This doesn't mean someone won't get heavy rain today or severe weather, just that models can't pinpoint what areas have a greater chance.



Hail Risk:


Satellite Image (1KM)


NEXRAD Mosaic Radar

[kevinpate]

I'm ready for the rain to take a multi-day break. I know folks whose work mandates dry weather so they can tackle their tasks. They're a tad restless when it stays wet like this.
That sat photo certainly wouldn't raise their spirits.

[westsidesooner]

I have to admit I'm ready for some dry sunny weather too. Hopefully the rain will hold off long enough this evening for me to get the lawn mowed. Before the neighbors start complaining. From the latest hazrdous weather outlook its sounds like the NWS will be focusing their attention on north cetral through central Oklahoma this afternoon. There should be several outflow boundaries around (although they are hard to pic up right now on radar and sat.) The new SPC outlook should be out by noon. Be interesting to see if anything changes in their discussion from this morning. Til then... heres the NWS discussion.

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NORMAN OK
1014 AM CDT THU APR 30 2009

TIMING...
THE MOST LIKELY TIME FOR SEVERE THUNDERSTORMS WILL BE FROM 4 PM
THROUGH THE NIGHT.

IMPACTS...
SOME DAMAGE TO VEGETATION...AUTOMOBILES...AND HOMES...FROM HAIL TO
THE SIZE OF TENNIS BALLS.

LOCALLY SIGNIFICANT WIND DAMAGE FROM 75 MPH WINDS.

A LOW CHANCE OF TORNADOES.

DISCUSSION...
RICH GULF MOISTURE WAS IN PLACE. DEWPOINTS WILL RISE INTO THE MIDDLE
AND LOCALLY UPPER 60S...WHILE A COLD FRONT APPROACHES FROM THE
NORTHWEST. FROM MIDDAY INTO THE AFTERNOON...A SMALL COMPLEX OF
THUNDERSTORMS WILL MOVE JUST EAST OF STILLWATER...DOWN TO INTERSTATE
40. THIS WILL PRODUCE AN OUTFLOW BOUNDARY ORIENTED NORTHWEST TO
SOUTHEAST ACROSS CENTRAL AND NORTH CENTRAL OKLAHOMA. ELSEWHERE...THE
ENTIRE REGION WILL RECEIVE PLENTY OF HEATING...RESULTING IN STRONG
INSTABILITY...WITH CAPE VALUES GREATER THAN 2500...AND POSSIBLY
APPROACHING 3500 LATE THIS AFTERNOON. CAP STRENGTH WILL BE GREATEST
TO THE WEST...AND WEAKEST NEAR THE OUTFLOW BOUNDARY. THE FRONT WILL
MOVE INTO NORTHWEST OKLAHOMA...AND A WIND SHIFT...OR TROUGH AHEAD OF
THE FRONT IS EXPECTED TO BECOME THE FOCUS FOR THUNDERSTORM
DEVELOPMENT LATE THIS AFTERNOON. THE TROUGH WILL EXTEND FROM NEAR
PONCA CITY TO WATONGA AND MANGUM. THE MOST NUMEROUS STORMS ARE
EXPECTED WHERE THE TROUGH OVERTAKES THE OUTFLOW BOUNDARY IN NORTH
CENTRAL AND CENTRAL OKLAHOMA. INITIALLY...MODERATE WIND SHEAR AND
STRONG INSTABILITY MAY RESULT IN SUPERCELLS...WITH A RISK OF VERY
LARGE HAIL...AND AT LEAST A LOW CHANCE OF TORNADOES. THE STORMS MAY
QUICKLY GROW INTO A COMPLEX...HOWEVER...AND BEGIN TO MOVE SOUTH AND
SOUTHEAST...WITH AN INCREASING THREAT OF DAMAGING WINDS...IN
ADDITION TO LARGE HAIL.

[Thunder]

Oh the HUMIDITY!!!

Yeah, I'm waiting on that data to come out. It should be anytime now.

[Thunder]

Jon at KFOR is calling for a Moderate Risk throughout North Central, including the metro, for later today. Areas surrounding the Moderate Risk is also at risk as well, especially under Slight Risk. Highlighted areas on the weather map is only an estimate.

Main risks is heavy rain, lightning, wind, and large hail. Isolated tornadoes is possible.

[Thunder]

Latest NWS Discussion

SKIES WILL SLOWLY DETERIORATE AS THE DAY PROGRESSES. MVFR CONDITIONS
AT BEST ARE EXPECTED FOR THE CENTRAL AND NORTHERN SITES. LATER
THIS EVENING THROUGH TOMORROW...LIFR CONDITIONS ARE EXPECTED FOR
THE NORTHERN SITES WITH LOW CEILINGS AND REDUCED VISIBILITY. THERE
IS UNCERTAINTY AS TO WHERE AND WHEN THUNDERSTORMS WILL FORM LATER
THIS AFTERNOON. THERE IS A GOOD CHANCE THAT KOKC...KOUN...AND KPNC
WILL AT LEAST HAVE STORMS IN THE AREA.

[venture]

MCD out for the NE counties.



MESOSCALE DISCUSSION 0645
NWS STORM PREDICTION CENTER NORMAN OK
0155 PM CDT THU APR 30 2009

AREAS AFFECTED...NERN OK...NWRN AR

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 301855Z - 302100Z

REMNANT MCV IS SHIFTING ENEWD ACROSS NCNTRL AR WITH BREAKS IN
EXPANSIVE CLOUDINESS NOW OCCURRING NORTH OF OUTFLOW BOUNDARY WITHIN
COOLER AIRMASS OVER WCNTRL AR/ECNTRL OK. WEAK WARM ADVECTION
APPEARS PRIMARILY RESPONSIBLE FOR ONGOING ELEVATED CONVECTION ALONG
WRN PERIPHERY OF SFC MESO-SCALE COLD DOME. WITH TIME THIS ACTIVITY
MAY CONGEAL AND BECOME ROOTED A BIT LOWER AS IT APPROACHES STEEPER
BOUNDARY LAYER LAPSE RATE ENVIRONMENT ALONG I-40 OVER AR. IF THIS
OCCURS...UPWARD GROWTH IS POSSIBLE AND SEVERE THREAT WOULD INCREASE.
LARGE HAIL AND DAMAGING WINDS ARE THE MAIN SEVERE THREATS.

..DARROW.. 04/30/2009

[bretthexum]

Venture, see those 2 outflow boundries parked right over OKC? Yikes. Same thing happened in KS last night and they got about 6 naders. I'm hoping for just hail, but sometimes those colliding boundries spin up, even with minimal shear.

[Thunder]

It looks like the Low is still tracking SE. Have that changed, Venture?

The dryline out west is entering the state. I still think that the metro have a decent chance.

Venture?

[Luke]

Off at 4:00, home by 4:30... I'm hoping nothing happens by then.

I HAVE to mow!

[Thunder]

Off at 4:00, home by 4:30... I'm hoping nothing happens by then.

I HAVE to mow!

Me too. I got a couple of mowing to do, but I'm delaying all that.

[Charlie40]

Get a goat they can mow rain or shine

[Luke]

Get a goat they can mow rain or shine

Although I do live in Del City, I don't think a backyard goat would fly.

[Thunder]

Although I do live in Del City, I don't think a backyard goat would fly.

My aunt way out in the small town next to Checotah (forgot the name) had a goat. It was very cute! That was a long time ago and she got rid of him, because he was interfering with the neighbors, getting on top of cars, etc. They are capable of jumping the fence.

[Thunder]

Rainfall totals for today and tomorrow.

(Pix may change since the time of this post.)

.DISCUSSION...ALL THE NECESSARY INGREDIENTS FOR FLOODING WILL REMAIN
IN OUR REGION THROUGH SUNDAY. ALTHOUGH IT WILL NOT RAIN CONSTANTLY
AT ANY LOCATION...WE ANTICIPATE CLUSTER OF THUNDERSTORMS WITH HEAVY
RAIN...AND AT SOME TIMES WE WILL SEE ORGANIZATION ON LARGER SCALES.
EVEN THE MOST ISOLATED STORMS WILL PRODUCE TORRENTIAL RAIN...AS WE
MAINTAIN A DEEP FETCH OF TROPICAL MOISTURE...WITH DEWPOINTS HANGING
IN THE 60S TO NEAR 70 OUT AHEAD OF A COLD FRONT. COMBINING THIS
REASONING WITH RECENT HEAVY RAINS AND LOW FLASH FLOOD GUIDANCE
VALUES /MEANING THAT IT WILL TAKE LITTLE RAIN TO PRODUCE FLASH
FLOODING/ WE CHOSE TO ISSUE A FLASH FLOOD WATCH THAT IS NECESSARILY
LARGE AND LONG LIVED...THROUGH SUNDAY.

THIS AFTERNOON...WARMER MID LEVEL TEMPERATURES HAD OVERSPREAD THE
AREA FROM THE WEST...BUT LAPSE RATES REMAINED STEEP...YIELDING LARGE
MEASURES OF INSTABILITY. THE CAP WILL LIMIT THE NUMBER OF EVENING
THUNDERSTORMS...BUT A FEW ARE LIKELY TO FORM...FIRST NEAR THE
INTERSECTION OF AN OUTFLOW BOUNDARY AND SURFACE TROUGH IN NORTHWEST
OR NORTH CENTRAL OKLAHOMA...AND SECOND IN AN ISOLATED FASHION
SOUTHWARD THROUGH WESTERN OKLAHOMA AND POSSIBLY WESTERN NORTH TEXAS.
ANY OF THESE STORMS MAY PRODUCE VERY HEAVY RAIN AND SOME SEVERE
WEATHER. THE STORMS FARTHER NORTH...HOWEVER...WILL HAVE A BETTER
OPPORTUNITY TO MERGE AND GROW UPSCALE INTO A COMPLEX. IF THIS
OCCURS...THE COMPLEX MAY PROPAGATE SOUTHWARD INTO THE LOW LEVEL JET
OVERNIGHT...POSSIBLY REACHING THE RED RIVER. THIS WAS ONE REASON TO
TAKE THE FLOOD WATCH ALL THE WAY TO OUR SOUTHERN BORDER.

MEANWHILE...SOMEWHAT INDEPENDENT OF THE EVENING ACTIVITY...WE WILL
SEE A STRONGLY FORCED AREA FOR ASCENT DEVELOP IN KANSAS AND FAR
NORTHERN OKLAHOMA TOWARD MORNING...WITH THE LOW LEVEL JET IMPINGING
ON A ZONE OF MID LEVEL FRONTOGENESIS. THIS MAY SUSTAIN RAIN AND
STORMS INTO FRIDAY MORNING. THEN THE FOCUS WILL SHIFT TO A SURFACE
FRONT THAT SHOULD CATCH UP TO THE PRE FRONTAL TROUGH ON FRIDAY...AND
MAY LIGHT UP WITH ADDITIONAL STORMS SOUTHWEST TO NORTHEAST ACROSS
OUR FORECAST AREA. THESE WILL AGAIN FEED ON THE LOW LEVEL JET AND
ABUNDANT MOISTURE GOING INTO SATURDAY MORNING. BY THAT TIME...
OUTFLOWS WILL BECOME INCREASINGLY IMPORTANT...AND OUR UNCERTAINTY
INCREASES. HOWEVER...MODELS ARE CONSISTENT IN BRINGING A WELL
DEFINED UPPER LEVEL TROUGH THROUGH THE REGION SATURDAY NIGHT INTO
SUNDAY...CAUSING A WAVE ON THE FRONT...AND SPREADING RAIN WELL UP TO
THE NORTH OF THE FRONT WITHIN A ZONE OF HEIGHT FALLS. THEREFORE...IF
FLOODING IS A PROBLEM...IT MAY CONTINUE TO BE A PROBLEM EVEN WELL
NORTH OF THE SURFACE FRONT. THIS WAS ANOTHER REASON TO TAKE THE
FLOOD WATCH OUT FAR IN TIME...THROUGH SUNDAY.

AT 3 PM...AN OUTFLOW BOUNDARY FROM EARLIER THUNDERSTORMS EXTENDED
FROM NEAR CHANDLER TO NEAR ENID... A WEAK SURFACE LOW PRESSURE
AREA NEAR ARNETT. A DRYLINE EXTENDED FROM THE LOW INTO EASTERN PARTS
OF THE TEXAS PANHANDLE. AHEAD OF THESE BOUNDARIES...TEMPERATURES HAD
WARMED INTO THE 70S AND LOWER 80S WITH DEWPOINT TEMPERATURES
GENERALLY IN THE MID TO UPPER 60S.

THE AIRMASS CONTINUES TO DESTABILIZE THIS AFTERNOON AHEAD OF THE
SURFACE BOUNDARIES...ESPECIALLY ACROSS WESTERN PARTS OF OKLAHOMA AND
NORTH TEXAS WHERE TEMPERATURES HAVE WARMED INTO THE LOWER TO MID
80S. SCATTERED THUNDERSTORMS MAY INITIATE IN THE VICINITY OF THE
SURFACE BOUNDARIES AS THE CAP WEAKNES LATER THIS AFTERNOON.

IF STORMS CAN DEVELOP...INSTABILITY AND SHEAR WILL BE FAVORABLE FOR
SEVERE STORM DEVELOPMENT.

[venture]

MESOSCALE DISCUSSION 0647
NWS STORM PREDICTION CENTER NORMAN OK
0513 PM CDT THU APR 30 2009

AREAS AFFECTED...NCNTRL OK

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 302213Z - 302345Z

A SEVERE THREAT MAY DEVELOP THIS EVENING IF THUNDERSTORMS CAN
INITIATE IN NRN AND CNTRL OK. THE STORMS SHOULD BE CAPABLE OF
PRODUCING LARGE HAIL AND AN ISOLATED TORNADO/WIND DAMAGE THREAT. THE
AREA WILL BE CLOSELY MONITORED FOR SIGNS OF STORM INITIATION WITH WW
ISSUANCE POSSIBLE.

LATEST SFC ANALYSIS SHOWS A WELL-DEFINED OUTFLOW BOUNDARY FROM
WOODWARD EXTENDING ESEWD TO NEAR GUTHRIE AND MUSKOGEE. NORTH OF THE
BOUNDARY...THE AIRMASS IS STRONGLY CAPPED AND THE RUC SUGGESTS
LOW-LEVEL CONVERGENCE IS INCREASING ALONG THE BOUNDARY ITSELF. IN
SPITE OF WEAK LARGE-SCALE FORCING...STORM INITIATION REMAINS
POSSIBLE SOMETIME FROM EARLY TO MID EVENING ESPECIALLY IF LOW-LEVEL
CONVERGENCE CAN CONTINUE TO INCREASE. IF STORMS CAN
INITIATE...REGIONAL PROFILERS ACROSS THE MCD AREA SUGGEST ABOUT 40
KT OF 0-6 KM SHEAR EXISTS. IN ADDITION...RUC ANALYSIS SHOWS MODERATE
TO STRONG INSTABILITY ALONG AND SOUTH OF THE BOUNDARY. THIS
ENVIRONMENT SHOULD EASILY SUPPORT A THREAT FOR SUPERCELLS WITH A
TORNADO...LARGE HAIL AND ISOLATED WIND DAMAGE POSSIBLE.

[venture]

This gives a good idea where they are watching. This is from the SPC's mesoscale analysis page showing current moisture convergence.

[venture]

MESOSCALE DISCUSSION 0648
NWS STORM PREDICTION CENTER NORMAN OK
0536 PM CDT THU APR 30 2009

AREAS AFFECTED...NWRN TX...SWRN OK

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 302236Z - 302330Z

CORRECTED FOR LOCATION

ISOLD THUNDERSTORM DEVELOPMENT IS POSSIBLE OVER NWRN TX AND SWRN OK
OVER THE NEXT FEW HOURS. SHOULD INITIATION OCCUR...STORMS WILL
LIKELY QUICKLY BECOME SEVERE. AREA IS BEING MONITORED FOR A POSSIBLE
WW.

VISIBLE SATELLITE IMAGERY SHOWS A LINE OF CU DEVELOPING ALONG THE
DRYLINE IN NWRN TX. ALTHOUGH VISUAL APPEARANCE OF THE CU AND CURRENT
MESOANALYSIS INDICATE WEAK CINH REMAINS...STRONG SURFACE HEATING
OVER THE NEXT FEW HOURS MAY ACT TO SUFFICIENTLY WEAKEN THE
CAP...ALLOWING STORMS TO RAPIDLY DEVELOP. UNCERTAINTY LIES IN THE
RELATIVELY WEAK CONVERGENCE ALONG THE DRYLINE...AND GENERAL RIDGING
ALOFT. SHOULD STORMS DEVELOP...THEY WILL LIKELY QUICKLY BECOME
ROOTED AT THE SURFACE AND BECOME SEVERE IN A VERY UNSTABLE AIRMASS.
GIVEN VERY STEEP LAPSE RATES AND 40 KTS OF 0 TO 6 KM NWLY BULK
SHEAR...SUPERCELLS CAPABLE OF LARGE HAIL AND DMGG WINDS CAN BE
EXPECTED. AREA IS BEING MONITORED FOR A POSSIBLE WW. SHOULD
INITIATION APPEAR TO BE IMMINENT...A WW WILL NEED TO BE ISSUED
QUICKLY.

..HURLBUT.. 04/30/2009

[Luke]

The lawn is mowed! Rain, commence!

[Thunder]

Storms is firing far SW. This could be da bomb!

[venture]

Nothing down to the SW yet except for some false echoes on radar. There is some development in the NE now. One other area that really has my attention right now is in NW Oklahoma where there seems to be a very thick CU developing there now.

[Thunder]

I was just watching Mike and he was pinpointing clouds starting to go up in the SW area, I think the TX area. I was putting together wooden birds to hang outside under the tree.

[venture]

There are some down there, but they aren't doing much.

Oklahoma 1km Resolution Radar and Satellite Imagery

[Thunder]

The ones you mentioned in the NW, what direction are they moving?

[OKCisOK4me]

I was just watching Mike and he was pinpointing clouds starting to go up in the SW area, I think the TX area. I was putting together wooden birds to hang outside under the tree.

Cause the would...attract...the storms and....make them comes toward OKC? lol