DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 191252
SWODY1
SPC AC 191251

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0751 AM CDT WED MAR 19 2014

VALID 191300Z - 201200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A SERIES OF MIDLEVEL IMPULSES...CURRENTLY EXTENDING ACROSS THE MID
MS/LOWER OH VALLEYS TOWARD THE LOWER GREAT LAKES PER WATER VAPOR
IMAGERY...WILL PROGRESS E/NEWD THIS FORECAST PERIOD AS A CYCLONIC
MID-UPPER LEVEL FLOW REGIME DEVELOPS EAST OF THE PLAINS STATES.
REINFORCEMENT OF THIS CYCLONIC FLOW WILL OCCUR AS ADDITIONAL
UPSTREAM IMPULSES ADVANCE SEWD AND EWD ACROSS THE NRN AND CENTRAL
PLAINS...RESPECTIVELY...PHASING INTO THE OH VALLEY AS A NEGATIVELY
TILTED TROUGH BY 12Z THU. MEANWHILE...A SHORTWAVE TROUGH AND
ATTENDANT POLAR JET STREAK...CURRENTLY MOVING INTO SWRN BRITISH
COLUMBIA AND ADJACENT NWRN WA...WILL ADVANCE EWD ACROSS THE REST OF
BC/AB AND THE FAR NORTHWEST STATES TROUGH TONIGHT.

...MIDDLE-UPPER OH VALLEY AND SRN LOWER MI...
AT 11Z...AN AREA OF LOW PRESSURE WAS CENTERED JUST WEST OF CHICAGO
WITH THIS FEATURE EXPECTED TO TRACK NEWD REACHING FAR SWRN QUEBEC BY
12Z THU. A COLD FRONT TRAILING SSWWD FROM THE LOW WILL ADVANCE EWD
REACHING THE UPPER OH VALLEY TO THE CENTRAL GULF COAST STATES BY
EARLY THIS EVENING. ONGOING TSTM ACTIVITY LOCATED ALONG AND EITHER
SIDE OF THE OH RIVER INTO FAR SRN IND AND FAR NWRN KY APPEARS TO BE
WITHIN A ZONE OF STRONGEST WAA AT 700 MB PER OBJECTIVE ANALYSIS.
GIVEN THIS FACTOR IMMEDIATELY UPSTREAM FROM THE 12Z ILN SOUNDING...
ADDITIONAL LOW-MID LEVEL DESTABILIZATION IS POSSIBLE ACROSS MUCH OF
THE OH VALLEY INTO THE AFTERNOON. DPVA ATTENDANT TO THE MID LEVEL
IMPULSES MOVING THROUGH THIS REGION SHOULD CONTINUE TO PROMOTE
CONVECTION/TSTM DEVELOPMENT WITH EWD EXTENT...POSSIBLY REACHING FAR
WRN PA LATE THIS AFTERNOON.

...E OF THE APPALACHIANS FROM ERN PA/NJ INTO SRN NEW ENGLAND...
THERE WILL BE SOME LOW LEVEL MOISTENING AND WAA ALONG AND EAST OF
THE CENTRAL APPALACHIANS TODAY AS SLY LOW LEVEL WINDS STRENGTHEN IN
RESPONSE TO HEIGHT FALLS WITH THE APPROACH OF THE OH VALLEY/GREAT
LAKES TROUGH. THE LACK OF GREATER MOISTURE VALUES PRESENT ACROSS
THE ERN SEABOARD REGION AND UNCERTAINTY IN THE DEGREE OF COOLING AT
500 MB THIS AFTERNOON/EVENING SUGGESTS INSTABILITY SHOULD BE RATHER
MEAGER. SOME CONVECTION WILL BE POSSIBLE ALONG AND EAST OF THE
CENTRAL APPALACHIANS TOWARD SRN NEW ENGLAND LATER THIS AFTERNOON
INTO THE EVENING AS FORCING FOR ASCENT INCREASES IN THE EXIT REGIONS
OF STRONG WLY 500 MB AND 250 MB JETS. HOWEVER...THE LIKELIHOOD FOR
INSTABILITY TO EXTEND INTO FAVORABLE ICING LAYERS FOR LIGHTNING
GENERATION AND SUPPORT TSTM COVERAGE OF AT LEAST 10 PERCENT REMAINS
LOW. TSTM COVERAGE MAY BE GREATER LATE TONIGHT /AFTER 06Z/ AS
FORCING FOR ASCENT ADVANCES OFFSHORE THE MID ATLANTIC STATES AND SRN
NEW ENGLAND WHERE THE PRESENCE OF GREATER THETAE WILL PROVE
SUFFICIENT FOR RELATIVELY STRONGER INSTABILITY FOR TSTM DEVELOPMENT.

...WA/NORTHERN ID...
SUFFICIENT FORCING FOR ASCENT ATTENDANT TO THE BC/NWRN WA SHORTWAVE
TROUGH/JET STREAK SHOULD COINCIDE WITH STEEPENING LAPSE RATES/VERY
WEAK INSTABILITY FOR SHALLOW CONVECTION ACROSS THE REGION LATER
TODAY. ISOLATED LIGHTNING STRIKES MAY BE POSSIBLE PARTICULARLY FROM
MID-AFTERNOON THROUGH EARLY EVENING ACROSS FAR ERN WA/FAR NRN ID.

..PETERS/EDWARDS.. 03/19/2014

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