Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS02 KWNS 021734
SWODY2
SPC AC 021733

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1233 PM CDT MON MAY 02 2016

VALID 031200Z - 041200Z

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS THE MID-ATLANTIC AND
SOUTHEAST STATES...

...SUMMARY...
SCATTERED THUNDERSTORMS...A FEW STRONG...ARE EXPECTED TO DEVELOP
AHEAD OF A COLD FRONT ACROSS THE SOUTHEASTERN STATES AND MIDDLE
ATLANTIC REGION TUESDAY.  GUSTY WINDS AND PERHAPS SOME HAIL ARE THE
MAIN THREATS.  ADDITIONAL STORMS...SOME PRODUCING SMALL HAIL AND
LOCALLY STRONG WIND GUSTS...WILL BE POSSIBLE IN THE UPPER GREAT
LAKES REGION AND PART OF THE SOUTHERN PLAINS.

...SYNOPSIS...
A LOW-LATITUDE BRANCH OF WESTERLIES IS EXPECTED TO PERSIST FROM
MEXICO THROUGH THE GULF BASIN AND FL THROUGH TUESDAY NIGHT...WHILE
THE MID-UPPER LEVEL FLOW PATTERN BECOMES HIGHLY AMPLIFIED ACROSS THE
U.S. AND CANADA.  AT THE SURFACE...A COLD FRONT WILL MOVE SLOWLY
EAST ACROSS THE MID-ATLANTIC AND SOUTHEAST STATES.  THIS BOUNDARY
AND TWO OTHER FRONTS ACCOMPANYING SHORTWAVE TROUGHS INTO THE UPPER
GREAT LAKES/UPPER MS VALLEY AND SOUTHERN PLAINS WILL BE FOCI FOR
TSTM DEVELOPMENT ON TUESDAY.

...MID-ATLANTIC AND SOUTHEAST STATES...
WEAK HEIGHT FALLS...WEAK CONVERGENCE ALONG THE COLD FRONT...AND
CONTINUED UNCERTAINTY IN THE DEGREE OF DESTABILIZATION ACROSS THESE
AREAS ON TUESDAY AHEAD OF AN AMPLIFYING UPPER TROUGH MAINTAINS A
MARGINAL SEVERE RISK WITH THIS OUTLOOK ISSUANCE.  ONGOING
PRECIPITATION/CLOUDINESS ACROSS MUCH OF THIS REGION IS EXPECTED TO
INHIBIT STRONGER DIABATIC HEATING.  AREAS WITH CLOUD BREAKS IN THE
WAKE OF EARLY DAY CONVECTION MAY RESULT IN SOME GREATER
DESTABILIZATION...THOUGH WEAK MIDLEVEL LAPSE RATES SHOULD LIMIT
STRONGER INSTABILITY FROM BEING OBSERVED.

STRENGTHENING SHEAR PROFILES AHEAD OF DIGGING UPPER TROUGH SUGGEST
SOME CONVECTIVE ORGANIZATION WILL BE POSSIBLE.  GUSTY WINDS AND
MARGINALLY SEVERE HAIL ARE THE PRIMARY THREATS WITH ORGANIZED
MULTI-CELL UPDRAFTS...WITH OVERALL SEVERE STORM COVERAGE BEING
LIMITED BY THE OCCURRENCE OF WEAK INSTABILITY.

...FL...
WATER-VAPOR IMAGERY SHOWED AN IMPULSE MOVING EAST ACROSS SOUTHERN
BAJA THIS MORNING...WITH MODELS SUGGESTING THIS LOW-AMPLITUDE TROUGH
WILL MOVE EAST ACROSS THE GULF BASIN TOWARD FL ON TUESDAY.  DESPITE
THE LACK OF STRONGER FORCING ALOFT...STRENGTHENING WESTERLY MIDLEVEL
WINDS AND MODERATE INSTABILITY /ESPECIALLY ACROSS EAST-CENTRAL AND
SOUTHEAST FL/ WILL SUPPORT STORM ORGANIZATION.  A FEW STORMS COULD
BECOME STRONG TO SEVERE.

...UPPER MS VALLEY/UPPER GREAT LAKES REGION...
A GENERAL TSTM AREA HAS BEEN ADDED FOR MUCH OF THE UPPER GREAT LAKES
REGION INTO A PORTION OF THE UPPER MS VALLEY AS LOW-TOPPED SHOWERS
AND TSTMS ARE EXPECTED TO DEVELOP WITH THE APPROACH OF AN
EQUATORWARD-MOVING SHORTWAVE TROUGH.  FORCING FOR ASCENT AND
STEEPENING LAPSE RATES WITHIN THE EXIT REGION OF A NORTHERLY 60-80
KT 500-MB JET WILL PROVE FAVORABLE FOR CONVECTIVE DEVELOPMENT.
THESE TSTMS SHOULD BE FOCUSED ALONG A SOUTHWARD-MOVING COLD
FRONT...WITH SMALL HAIL POSSIBLE...GIVEN COLD 500-MB TEMPERATURES
/-22 TO -24 C/ AND WEAK INSTABILITY.

...SOUTHERN PLAINS...
HIGH-BASED SHOWERS AND TSTMS ARE EXPECTED TO DEVELOP TUESDAY
AFTERNOON INTO THE EARLY EVENING ACROSS WESTERN PORTIONS OF OK...THE
OK/TX PANHANDLES TO NORTHWEST TX.  PRIMARY SUPPORT WILL BE FROM
FORCING FOR ASCENT SPREADING ACROSS THIS REGION ATTENDANT TO A
SOUTHWARD-MOVING SHORTWAVE TROUGH.  COLD 500-MB TEMPERATURES /-18 TO
-20 C/...STEEPENING LAPSE RATES...AND EFFECTIVE BULK SHEAR OF 25-35
KT SHOULD PROVE FAVORABLE FOR A FEW STORMS TO PRODUCE SMALL HAIL.
THIS ACTIVITY WILL TEND TO BE HIGH-BASED WITH 35-40 DEGREE SURFACE
TEMP/DEW POINT SPREADS ALSO SUPPORTING LOCALLY STRONG WIND GUSTS.

..PETERS.. 05/02/2016

$$


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