Flash Flood Warning 10, NWS State College, PA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
530 PM EDT WED JUN 13 2001

SENDING UPDATE FOR ONGOING CONVECTION OVER SWRN CWA. PCPN MAINLY
CONFINED TO SRN SOMERSET COUNTY ATTM. WILL INCLUDE 50 POP IN AN FOR
THIS EVENING PD AND ADD PHRASING TO HIGHLIGHT POSS LOCALLY HEAVY
RAINFALL BASED ON SLOW MOVING CELLS IN DEEP LAYERED MOISTURE.

WILL ALSO ADD 30 POP IN AN EVENING PD FOR CAMBRIA...BLAIR AND
BEDFORD COUNTIES AND GROUP THEM OFF FROM PVS BREAKOUTS.

NO OTHER CHANGES ATTM.

GARTNER

************* PVS AFD BELOW *****************************************

...WILL ALLISON BRING RAIN TO SOUTHERN PA?...

A QUIETER AFTERNOON OVER PA COMPARED TO YESTERDAY WITH MOST
CONVECTION TO OUR SOUTH.  THE FOCUS OF THIS RAIN OVER THE MTS AND
THE EASTERLY FLOW IS PROBABLY THE FIRST RAIN ASSOCIATED WITH THE
FLOW AROUND THE REMNANTS OF ALLISON. BOTH THE AVN AND ETA SHOW -1
STD DEVIATION EASTERLY WIND ANOMALIES IN THE MID-ATLANTIC REGION
ALREADY.  THIS ANOMALOUS EASTERLY FLOW WILL BE A DOUBLE EDGED SWORD
FOR PA OVER THE NEXT 48 HOURS OR SO.

THE MODELS SHOW A STRONG AND RIDGE OF THE EASTERN US AND CANADA.
1000-850 THICKNESS ANOMALIES OVER SRN CANADA AND NEW ENGLAND WILL
GET QUITE HIGH...HOT TO OUR NORTH. BUT THE EASTERLY FLOW WILL KEEP
PA TEMPS AND ANOMALIES CLOSER TO NORMAL. THE TIGHT MESOSCALE RIDGE
IN THE ETA/MM5 SOLUTIONS WOULD ALLOW MORE SUN THE CLOUDS THUR. BUT
WITH POTENTIAL CLOUDS HAVE LOWERED TEMPS BIT.  PA IS NOT TYPICALLY
IN THE UPPER 80S AND 90S WITH EASTERLY FLOW!  THE AVN SHOWS A -4.5
850 U WIND ANOMALIES THURS AFTERNOON AIMED ACROSS VA WITH NEAR -2 IN
SRN PA. FLOW INTO OUR MTS WILL CAUSE MORE CLOUDS IN SERN PA....LESS
CLOUDS TO NORTH AND WEST.  THIS WIND MAX MOVES INTO PA OVERNIGHT
THURS INTO FRIDAY. AVN WOULD BE WETTER AND CLOUDIER SOLUTION THEN ETA...THIS
IS A LOW CONFIDENCE FORECAST...BUT HAD TO PUT RAIN IN SE. SREF DATA
SHOWS MANY MEMBERS WITH 0.1 TO 0.25 INCHES OF RAIN...BUT NONE WITH
0.50 IN SE PA.

TEMPS WILL BE LOWER THEN GUIDANCE IN ERN ZONES FRI WITH HIGHER
POPS...LEANING TOWARD AVN POT SOLUTION.  THEN COLD FRONT COMES IN
FROM WEST.  THE SOUTHERLY WIND ANOMALY WITH THIS IT MOVES THROUGH
THE MIDWEST IS INTERESTING TOO.  IN ANY CASE...DRIER AIR MOVES W TO
EAST ACROSS PA SAT BRINGING A DEC IN HUMIDITY.  THE SOUTHERLY JET IS
NOW FORECAST TO INCREASE IN INTENSITY TO OUR EAST LATE SAT. IF THIS
HAPPENS FASTER AND TO WEST WE COULD SEE SOME INTERESTING WEATHER
HERE SAT AFTERNOON.

LONG TERM...
BIG DISAGREEMENT IN NCEP ENSEMBLES NEXT WEEK...WITH LARGE DISPERSION
OF MEMBERS OVER EASTERN US.  IN THE MEAN...HEIGHTS...TEMPS AND
T HICKNESS VALUES LOOK TO BE ABOUT NORMAL...TEMPS SHOULD BE NEAR
SEASONAL LEVELS.   BUT THE RIDGE OFF THE US COAST SUGGESTS WE COULD
BE A TAD MOIST.

.CTP...NONE.

GRUMM