Severe Thunderstorm Warning 245, NWS Norman, OK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
240 PM CDT TUE MAY 16 2000

ACTIVE AND COMPLICATED WX PATTERN TO PERSIST ACROSS THE FORECAST
AREA FOR THE NEXT COUPLE OF DAYS.  ALTHOUGH THE FOCUS FOR THIS
PACKAGE WILL CONTINUE TO BE THE POTENTIAL EVENT ON WED
EVENING..THERE ARE SEVERAL OTHER POSSIBLE FORECAST PITFALLS.
THE FIRST OF WHICH IS AN APPARENT POTENTIAL FOR CONTINUED SHOWER
ACTIVITY INTO TONITE FOR PARTS OF THE ERN ZONES.  INITIAL THOUGHTS
WERE TO HAVE A DRY FORECAST FOR TONITE..AS AREA SOUNDINGS SHOW A
VERY STRONG CAP.  HOWEVER..ACTIVITY OVR THE ERN ZONES REFUSES TO DIE
WITH BACKBUILDING OBSERVED AS FAR WEST AS I-35 AROUND MIDDAY. THIS
APPEARS TO BE ROOTED IN THE MID LEVELS IN THE NEARLY DRY ADIABATIC
LAPSE RATES ALOFT. WUD SUSPECT THAT AS THE MID LEVEL RIDGE AXIS IS
SHUNTED EWD TONITE AND SHARPENS WITH THE APPROACH OF THE UPPER
TROF..THIS ACTIVITY WUD COME TO AN END..BUT CURRENT OBS DO NOT
SUPPORT THIS ATTM..AND THE TREMENDOUS STREAM OF MID/HIGH LEVEL
MOISTURE SEEN ON CURRENT WV IMAGERY MAKES ME SUSPICIOUS THAT IT WILL
HANG AROUND FOR A WHILE. WILL WAIT UNTIL JUST BEFORE ISSUEANCE TIME
TO MAKE THE FINAL CALL ON THIS.

EVENT FOR LATE WED AFT AND WED EVE STILL BEARS WATCH..ALTHOUGH WE
ARE NOT INCREDIBLY EXCITED ABOUT THINGS ATTM.  WE DO BELIEVE THAT
THE MODEL FORECAST BOUNDARY LAYER DEWPOINTS..AND THUS CAPE..ARE
QUITE UNDERDONE.  HOWEVER..EVEN IF WE MAINTAIN DEWPOINTS IN THE MID
TO UPPER 60S EAST OF THE DRYLINE..WE ARE STILL NOT CONVINCED THERE
WILL BE WIDESPREAD DEVELOPMENT..YET.  UPSTREAM 500 TEMPS CONTINUE TO
BE VERY WARM /-9 TO -11/..AND IN ORDER INITIATE DEEP CONVECTION IN
SUCH A WARM ATMOSPHERIC COLUMN..WE WILL NEED TO GET SIGNIFICANT
HEATING AND RATHER STRONG LIFT THRU A DEEP LAYER TO GET PARCELS TO
LFC/S AOA 3000 METERS.  THE HEATING IS ALSO IN QUESTION AS THERE
WILL LIKELY BE CONSIDERABLE CLOUD COVER OVER THE ERN HALF OF THE
AREA THRU AT LEAST MIDDAY.  CURRENT THINKING IS THAT THERE WILL BE
SOME STORMS..BUT IT WILL LIKELY BE A RATHER LATE SHOW..WITH MOST
ACTIVITY HOLDING OFF UNTIL EVENING..AND DEVELOPING INVOF DRYLINE
WHICH SHUD SET UP ABOUT 2-3 COUNTIES DEEP INTO WRN OK. BASED ON
THESE UNCERTAINTIES..WE WILL NOT GO CRAZY WITH POPS.

ANOTHER POTENTIAL PITFALL..AND POSSIBLY MORE SIGNIFICANT EVENT..MAY
BE SHAPING UP OVER THE SRN ZONES ON THURSDAY.  ETA/AVN/CANADIAN
MODELS ARE ALL INDICATING THAT A TRAILING SHORT WAVE MAY SWING
AROUND THE BASE OF THE UPPER LOW. THE COLD FRONT SHUD BE INVOF I-44
WITH A TRIPLE POINT OVER SC OK BY AFTERNOON.  IF THIS DOES PLAY
OUT..ANOTHER ROUND OF SVR WX IS POSSIBLE.

EXTENDED FORECAST STILL LOOKS DRY FOR FRI AND SAT..ALTHOUGH WE WILL
NEED TO WATCH THE TREND FOR SAT AS WAA PATTERN SETS UP AGAIN. A
CHANCE OF SHOWERS AND STORMS RETURNS FOR SUNDAY IN NW FLOW.
 MILLER

PRELIM NUMBERS..SUBJECT TO CHANGE..
OKC   68  86  64  82 /  10  20  30  30
HBR   70  95  64  84 /  10  20  30  30
SPS   71  94  66  86 /  10  20  30  30
GAG   63  94  61  83 /  10  10  10  10
PNC   68  84  62  79 /  10  20  40  20
DUA   70  88  67  83 /  10  20  30  30

.OUN...
OK...NONE.
TX...NONE.