The SPC issues Moderate Risk for Severe Weather Tuesday for Plains

From the SPC:

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1255 AM CDT MON APR 25 2016

VALID 261200Z – 271200Z

…THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF SOUTHEAST
NEB…CENTRAL/EASTERN KS INTO CENTRAL OK…

…THERE IS AN ENH RISK OF SVR TSTMS ACROSS PARTS OF SOUTHERN
NEB…CENTRAL/EASTERN KS…MUCH OF OK AND NORTH TX…

…THERE IS A SLGT RISK OF SVR TSTMS ACROSS MUCH OF THE CENTRAL AND
SOUTHERN PLAINS…

…THERE IS A MRGL RISK OF SVR TSTMS FROM NEB TO THE MIDDLE RIO
GRANDE VALLEY…

…THERE IS A MRGL RISK OF SVR TSTMS ACROSS PORTIONS OF THE OHIO
VALLEY TO THE MID-ATLANTIC…

…SUMMARY…
SIGNIFICANT SEVERE THUNDERSTORMS WILL BE POSSIBLE ACROSS PARTS OF
THE SOUTHERN AND CENTRAL GREAT PLAINS TUESDAY AFTERNOON INTO THE
NIGHTTIME HOURS. TORNADOES…SOME STRONG…WILL BE POSSIBLE…IN
ADDITION TO VERY LARGE HAIL AND DAMAGING WINDS. ADDITIONAL ISOLATED
STRONG STORMS ARE POSSIBLE ACROSS PARTS OF THE OHIO VALLEY TO THE
MIDDLE ATLANTIC COAST REGION.

…CENTRAL AND SOUTHERN PLAINS…

…FORECAST PARAMETERS CONTINUE CONSISTENT SIGNAL FOR POTENTIAL
SEVERE WEATHER OUTBREAK ACROSS PORTIONS OF THE CENTRAL/SOUTHERN
PLAINS ON TUESDAY AFTERNOON/EVENING…

DETERMINISTIC AND ENSEMBLE GUIDANCE CONTINUES TO BE CONSISTENT WITH
BRINGING A NEGATIVELY TILTED TROUGH INTO THE PLAINS DURING THE
AFTERNOON/EVENING ON TUESDAY. A 60+ KT SOUTHWESTERLY MIDLEVEL JET
WILL OVERSPREAD TX INTO OK/KS BY EARLY AFTERNOON WITH STRONG DCVA.
THIS WILL BE ALIGNED WITH A SURFACE DRYLINE STRETCHING S/SW FROM
ROUGHLY CNTRL KS…WRN OK AND W-CNTRL TX BY 00Z/WED. THERE IS STILL
SOME VARIABILITY IN GUIDANCE WITH REGARDS TO THE SURFACE LOW
POSITION…BUT EXPECT THIS TO BE SOMEWHERE NEAR THE KS/NEB BORDER
WITH THE ATTENDANT WARM FRONT STRETCHING W-E NEAR/JUST NORTH OF THE
KS BORDER AT 00Z. RICH BOUNDARY LAYER MOISTURE WILL RESIDE ACROSS
THE WARM SECTOR WITH DEWPOINTS IN THE MID 60S TO NEAR 70 AS FAR
NORTH AS S-CNTRL/SE NEB. STRONG INSTABILITY AND VERY STEEP MIDLEVEL
LAPSE RATES WILL BE IN PLACE BY AFTERNOON…AND STRONG HEATING NEAR
THE DRYLINE SHOULD RESULT IN CONVECTIVE INITIATION BY LATE
AFTERNOON.

CONCERNING CONVECTIVE COVERAGE…UNCERTAINTY INCREASES WITH
SOUTHWARD EXTENT ACROSS OK INTO N TX. DEPENDING ON YOUR FAVORED
MODEL DEPICTION…A BI-MODAL COVERAGE PATTERN IS POSSIBLE WITH THE
INITIAL VORT MAX EJECTING NORTHEAST ACROSS N-CNTRL OK INTO KS AND
S-CNTRL NEB. ANOTHER VORT MAX WILL EJECT FURTHER SOUTH ACROSS
CNTRL/NRN TX LATER IN THE EVENING. THIS COULD LEAD TO A RELATIVE MIN
SOMEWHERE…BUT WHERE THIS IS REMAINS UNCLEAR AT THIS TIME.
REGARDLESS…AT LEAST ISOLATED TO WIDELY SCATTERED INTENSE
SUPERCELLS ARE EXPECTED ALONG THE DRYLINE…WITH GREATER COVERAGE IN
THE VICINITY OF THE TRIPLE POINT WHERE FORCING AND SHEAR WILL BE
MAXIMIZED. STRONG /POTENTIALLY LONG-TRACK/ TORNADOES…VERY LARGE
/PERHAPS GIANT/ HAIL AND DAMAGING WIND GUSTS WILL BE POSSIBLE WITH
ANY STORM THAT DEVELOPS ACROSS THE WARM SECTOR. AFOREMENTIONED
COVERAGE CONCERNS WILL PRECLUDE A HIGH RISK AT THIS TIME.

DURING THE EVENING INTO THE OVERNIGHT…STORMS MAY GROW UPSCALE INTO
AN MCS OR BOWING SEGMENTS ACROSS ERN KS INTO MO. WHILE A TORNADO
THREAT WILL LINGER NEAR THE WARM FRONT…A TRANSITION TOWARD MAINLY
A LARGE-HAIL AND DAMAGING-WIND THREAT IS EXPECTED WITH EASTWARD
EXTENT OVERNIGHT. ACROSS NRN/CNTRL TX…STRONGER FORCING WILL ARRIVE
DURING THE EVENING INTO THE OVERNIGHT HOURS AND SUPERCELLS MAY
DEVELOP LATER THAN FURTHER NORTH. THIS COULD LEAD TO A NIGHTTIME
TORNADO RISK BEFORE STORMS POTENTIALLY GROW UPSCALE AS THEY APPROACH
NORTHEAST TX. ADDITIONALLY…VERY LARGE HAIL AND DAMAGING WINDS WILL
BE POSSIBLE.

…OH VALLEY TO MID-ATLANTIC REGION…

A SHORTWAVE TROUGH WILL TRACK E/SE FROM THE GREAT LAKES TO THE
MID-ATLANTIC COAST BY 00Z/WED. THIS WILL BRING A BELT OF 45+ KT
MIDLEVEL W/NW FLOW ACROSS THE MARGINAL RISK AREA. AT THE SURFACE…A
COLD FRONT WILL SAG SOUTHWARD FROM THE GREAT LAKES TOWARD THE OHIO
VALLEY AND MID-ATLANTIC REGION DURING THE AFTERNOON/EVENING. SURFACE
DEWPOINTS WILL RANGE FROM THE LOW TO MID 60S WITH MODEST MIDLEVEL
LAPSE RATES IN PLACE. SOME CLOUDINESS IS EXPECTED…WHICH MAY LIMIT
DESTABILIZATION…BUT CAPE VALUES SHOULD BE ADEQUATE FOR WIDELY
SCATTERED TO SCATTERED STORM DEVELOPMENT DURING THE AFTERNOON AND
INTO THE EVENING NEAR THE SFC BOUNDARY. UNIDIRECTIONAL VERTICAL WIND
PROFILES WILL SUPPORT CLUSTERS AND LINE SEGMENTS. SOME STRONG WINDS
AND MARGINAL HAIL WILL BE POSSIBLE WITH THE STRONGEST STORMS.

..LEITMAN.. 04/25/2016



Author of the article:


Nick Lilja

Nick is former television meteorologist with stints in Amarillo and Hattiesburg. During his time in Hattiesburg, he was also an adjunct professor at the University of Southern Mississippi. He is a graduate of both Oregon State and Syracuse University that now calls Houston home. Now that he is retired from TV, he maintains this blog in his spare time.