WPC Met Watch |
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Mesoscale Precipitation Discussion: #0694 (2016) |
(Issued at 1008 PM EDT FRI SEP 23 2016
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MPD Selection |
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MESOSCALE PRECIPITATION DISCUSSION 0694
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1008 PM EDT FRI SEP 23 2016
AREAS AFFECTED...WESTERN NE...WESTERN SD INTO CENTRAL ND
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 240205Z - 240730Z
SUMMARY...CONVECTION TRAINING ACROSS PORTIONS OF FAR WESTERN NE
AND WESTERN SD COULD RESULT IN A FLASH FLOOD THREAT EXTENDING INTO
CENTRAL ND THROUGH INTO THE EARLY MORNING HOURS.
DISCUSSION...CONVECTION CONTINUES TO TRAIN ACROSS FAR WESTERN NE
AND WESTERN SD THIS EVENING. THE CONVECTION IS FOLLOWING AN AXIS
OF 500-1000 J/KG SURFACE BASED CAPE EXTENDING FROM FAR NORTHEAST
CO INTO SOUTHWEST ND...IN A RIBBON OF 1.25 TO 1.50 INCH
PRECIPITABLE WATER AIR. IR CLOUD TOPS CONTINUE TO COOL...WITH
TEMPERATURES NEAR -67 CELSIUS ACROSS FAR WESTERN SD... ASSOCIATED
WITH THE BEST CONVECTION.
WHILE THE KUDX RADAR HAS SHOWN HOURLY RAINFALL RATES BETWEEN 1.00
AND 1.50 INCHES OVER FAR WESTERN NE INTO SOUTHWEST SD...MESONET
SITES INDICATED THAT THE HOURLY RATES WERE CLOSER TO AN INCH. THE
00Z SOUNDINGS OUT OF RAPID CITY SHOWED A FAIR AMOUNT OF DRY AIR IN
THE MID LEVELS...INDICATING THE PRESENCE OF HAIL. THIS HAS BEEN
CONFIRMED BY HAIL REPORTS IN WESTERN SD EARLIER.
THE REGIONAL RADARS ALSO INDICATED THAT CONVECTION WAS TRYING TO
SPREAD NORTH NORTHEAST ALONG A LOW LEVEL CONVERGENCE ZONE FROM
WESTERN SD INTO CENTRAL ND... WHERE THE MOISTURE PROFILES WERE
BETTER. THE 00Z SOUNDINGS IN THE NORTHERN HIGH PLAINS SHOWED THAT
THE STRONG UNIDIRECTIONAL WIND PROFILE REMAINS IN PLACE...AND HIGH
RESOLUTION MODELS SHOWED LITTLE CHANGE EXPECTED THROUGH 06Z.
THE STRONG FLOW SHOULD RESULT IN A CONTINUATION OF THE TRAINING
SEEN ON REGIONAL RADARS. THE LATEST HRRR/EXPERIMENTAL HRRR SHOWED
A STRIPE OF 1.50 TO 2.00 INCHES OF RAINFALL WITH THE CONVECTION
ACROSS WESTERN SD INTO PORTIONS OF SOUTH CENTRAL ND...AS THE CELLS
TRACK NORTH...WHILE THE LINE MOVES SLOWLY EAST.
THERE IS ALMOST NO HIGH RESOLUTION GUIDANCE THAT TAKES THE
TRAINING CONVECTION INTO CENTRAL ND...BUT BASED ON RADAR TRENDS...
AS WELL AS INSTABILITY AND MOISTURE SEEN ON THE 00Z KBIS
RADAR...THE THREAT COULD EXTEND INTO THIS REGION.
TO THIS POINT...THE HRRR HAS BEEN TOO HIGH WITH ITS RAINFALL
AMOUNTS WITH THE TRAINING CONVECTION...AND COULD BE TOO HIGH GOING
FORWARD. IT IS POSSIBLE THAT THE SOUTHERN EDGE OF THE LINE STARTS
TO BECOME MORE OUTFLOW DOMINATED AS IT REACHES THE BETTER
INSTABILITY...WHICH COULD ALSO LIMIT THE FLASH FLOOD THREAT.
HOWEVER...THE TRAINING CONVECTION COULD STILL PRESENTS A FLASH
FLOOD THREAT INTO THE EARLY MORNING HOURS.
HAYES
ATTN...WFO...ABR...BIS...CYS...FGF...LBF...UNR...
ATTN...RFC...MBRFC...NCRFC...
LAT...LON 48690048 48489932 47849893 46949947 42980200
42310266 42570352 43040368 43580369 44520365
46430310 47730216
Last Updated: 1008 PM EDT FRI SEP 23 2016
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