Flash Flood Warning 20, NWS Burlington, VT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
820 PM EST MON JAN 12 1998

CURRENT SFC PRES FALL MAX VICINITY OF GEORGIAN BY OF LAKE HURON
INDICATES THERE WILL BE NO TRAPPED COLD AIR AHEAD OF THIS OVRRNG
EVENT.  IN FACT...A MUCH MORE CLASSIC STRONG NOCTURNAL SOUTHERLY JET
WILL OCCUR WITH ESPECIALLY STG WINDS DVLPG IN THE CHAMPLAIN VLY
ALONG WITH VERY MARKED TEMPERATURE RISE AND A LESS EFFECTIVE OVRRNG
PATTERN AS THE LOW LVL WARM FRONT SURGES NWRD.

TEMPERATURES SHOULD RISE FROM CURRENT READINGS AROUND 20 TO NEAR OR
ABOVE 40 BY THE TIME THE COLD FRONT ARRIVES AROUND NOON TUESDAY.
THE SOUNDING WILL BE BETTER MIXED THAN MODELS INDICATE WITH LESS
TEMPERATURE INVERSION THAN IS INCORRECTLY SHOWN ON THE MESOETA.  MIX
WITH SOME RAIN LIKLEY IN AT LEAST THE CHAMPLAIN VLY. FCST 45KT WINDS
AT 3K FEET MAY END UP AT THE ELEVATION OF THE VT CHAMPLAIN VLY
FOOTHILLS.

ALL MODEL QPFS WILL BE TOO HIGH.  LOCAL STUDY HAS SHOWN WINTER WARM
FRONTAL-SOUTH WIND EVENTS TYPICALLY PRODUCE ONLY A FRACTION OF THE
PRECIP FCST BY MODELS.  IN THIS PARTICULAR CASE...LEADING VORT
MOVING THRU THE MID ATLANTIC STATES IS CARRYING THE AVAILABLE PW MAX
OFFSHORE BEFORE IT CAN BE DRAWN INTO THE GREAT LAKES SYSTEM.
CURRENT HIGH DWPTS IN THE OH VLY ARE LIKELY ONLY VERY SHALLOW AND
NOT MUCH INDICATION OF TOTAL PRECIP EXPECTED FROM THE GREAT LAKES
SYSTEM.

A VERY BRIEF BUT POTENTIALLY CONVECTIVE WINDEX TYPE RAIN-CHGG-TO-
SNOW SQUALL IS LIKLY WITH THE SFC FRONTAL PASSAGE CONSIDERING RAPID
COOLING ALOFT AND WARMER THAN MODEL FCST LW LVL TEMPS.

BELL